texts: Chemistry of phosphodiester bond formation by DNA polymerase

texts:
As I'm teaching General Biology to my college students, I realized that I don't fully understand how a 3-P nucleotide like ATP is broken down to be incorporated into DNA during replication. How does this work??

In other words, what is the actual mechanism/reaction pathway for the following:

What I know:

I understand that ATP is typically hydrolyzed to become dephosphorylated in other contexts. I also understand that a phosphate of one nucleotide is bonded to a deoxyribose of an adjacent nucleotide via dehydration synthesis from the joining of their hydroxyl groups to form DNA.

However, I cannot seem to find a good resource (online or in any of my [admittedly simple] general bio textbooks) that demonstrate how exactly both of these reactions take place during replication...

I'm assuming that DNA polymerase is taking advantage of the released phosphates from ATP (and the appropriate forms of GTP, CTP, TTP) to become activated?

Overall, what does this whole process look like on a chemical/molecular level?

I'd love a visual (especially a video) if you could provide such a resource in addition to a thorough explanation of what's going on here.


texts: Do the recent findings of an ape-like creature in Europe with human-like teeth change the Out of Africa narrative?

texts:
http://www.telegraph.co.uk/science/2017/05/22/europe-birthplace-mankind-not-africa-scientists-find/

Two fossils of an ape with human-like teeth were discovered in Greece, and Bulgaria, and they are about 7.2 million years old.

Does this change the narrative of the 'Out of Africa' theory?

Have scientists in the relevant fields commented on this yet?


texts: How do cell signaling ensures time synchronization?

texts:
Let us suppose two cells A and B communicating with one another, I want to know how do cells ensure time synchronization while communicating. For instance, let us assume cell A sends a sequence '110'. Where '1' corresponds to dissemination of certain number of molecules, while '0' corresponds to no transmission of molecules. Now, cell B detects first '1', and then because of some delay in the reception of another '1', the sequence now received is '101'.
I want to know that how do cells ensure time synchronization?

Or because of very small distances over communication range, there is no need of it?


texts: is a musk deer's musk pod in its abdomen, its back, or its bottom/rear end?

texts:
I have read/heard different things about where a musk deer stores its perfume

Some links say it stores it in its abdomen just in front of its penis.  Others say the rectum(by which I suppose they mean the backside).

A) https://en.wikipedia.org/wiki/Deer_musk  "Deer musk is a substance with a persistent odor, obtained from a gland of the male musk deer situated in its back/rectal area. The substance has been extensively used as a perfume fixative, incense material, and medicine, since ancient times."

B) https://www.youtube.com/watch?v=r6CZKuSjlhI   7:40  "the fangs, but it's the other end of the deer that attracts more attention - the male's musk gland produces a scent that's irresistible to .. and perfume makers"

C) http://sandwalk.blogspot.co.uk/2009/10/are-you-sexually-attracted-to-male-musk.html   Only the mature male Moschus produces musk. The substance occurs in only one location on the deer's body: on its abdomen, just in front of its penis, is a hairy pouch known as the musk gland. This sac is about the size of a golf ball. It is composed of several layers of skin, with two openings immediately above the animal's urethra.

Quite a few links agree with 'C', that it's in the abdomen near the penis. Are wikipedia and national geographic wrong for putting the musk pod in the backside?


texts: What are the differences (if any) in brain activity when hallucinating versus perceiving a real object?

texts: I was wondering if there is difference in brain activity when someone is hallucinating an object, say a giraffe compared to when someone is genuinely observing a real giraffe?


texts: Why is the penicillin/ceftriaxone hypersensitivity test only done once?

texts:
I have had a severe bacterial infection. I was prescribed ceftriaxone, and when the time came for injecting it the nurse asked me whether I have an allergy to ceftriaxone. I answered that it's my first time, so she did the test and it was negative.

I was expecting a second test because as far as I know from type 1 hypersensitivity the body -  even if it is sensitive to an allergen - won't show a reaction the first time. The body makes the particular IgE and in the next exposure of same allergen it will have an allergic reaction.

So why is only one test done, considering the first two columns of the following picture?

From: Harsh Mohan's Pathology textbook 7E


texts: What is the distinction between chemokines, cytokines, interferons and interleukins?

texts:
They all seem to describe molecules of similar function and many people seem to use them interchangeably.

Also please include any other similar molecules if I've forgotten any in the list above.


texts: Since i had my first cell class at university i have heard about Cripsr Cas9 method. But I am quite surprised about one fact.  Why actually wasnt rewarded by Nobel price? Is it something like Einsteins relativity (to early to reward it)?


texts: Hypovolemia and orthostatic hypertension

texts: What is the physiological mechanism behind the occurrence of orthostatic hypertension in the presence of hypovolemia?


texts: Difference between Classic Satellite DNA and Microsatellites/Minisatellites

texts:
I am very new to this community and have a basic question about repetitive DNA sequences.

How is different (classic) satellite DNA from microsatellites/minisatellites?

All textbooks give concrete examples of microsatellites and/or minisatellites like --(AC)2--- or ---TACA(TAG)3--TACA----.

Are Classic Satellite DNA just sharing the same properties (perfect, imperfect, compound, complex, di-nucleotides, tri-nucleotides, etc.) as STRs or Minisatellites but the only difference is Classic Satellite DNA are longer?


texts:
I know when a plant cell becomes fully plasmolysed that the protoplast shrinks away and eventually is no longer joined to the cell wall.

Is this irrevocable damage? Can the cells survive it and continue to function if they are put back into a favourable solution.

If so how does the protoplast rejoin to the cell wall?


texts: Has anyone tried Gibson Assembly Optimizations?

texts: Has anyone tried the chew back-anneal in vitro DNA assembly method (known as Gibson Assembly) for difficult sequences, like GC-rich sequences? How big constructs could you efficiently assemble? Did you use the original protocol or some optimizations?


texts: Why are sequencing reads shorter than PCR products?

texts:
I have desinged and tested primers for RT-PCR, then purified the PCR products from the gels and send them to sequence at GATC (SUPREMERUN) using the forward primers.

After blasting the reads to refseq, I see that they are ~30% shorter than the PCR product. Example:

PCR expected length = 182 bp
Read length = 133 bp

I must mention that in the gels the expected PCR sizes were ok.

Does anyone have an idea what is the reason for this decrease in length?

Thanks


texts:
I'd like to identify this weed found in a garden in northern England at this time of year (March).
It reproduces using underground roots rather than flowers - so if you dig it up and leave any behind it grows again.
EDIT: here's a photo with the bulb cleaned a bit.


texts:
When we have some bacterial infection, say throat infection (pharyngitis) we take antibiotics as treatment. I was wondering how throat infection was treated when there was no antibiotics at all, before 1940's I think.

Throat infection is just example, It can be post surgical operation, urinary track infection etc, basically anything where we use antibiotics currently. So in a way replacement of antibiotic tablet when antibiotic wasn't available.


texts: Kinesin-5 / cytoplasmic dynein spatial density distribution in neurons

texts:
Is there some way to experimentally determine the density distribution of Kinesin and Dynein in a Neuron?
Fluorescence labeling would be impossible(?) as GFP markers would probably alter the motor dynamics.
Any ideas? Or do any studies exist which looked into this topic?


texts: It was found on a roof in Jaipur, Rajasthan, North-Western India.


texts: What was the reason for some plant and animals to become giant in course of evolution?

texts: The dinosaurs, mammoths, giant plants etc are known to be bigger than modern animals. I wonder why they had been lived and why they are not living now? I really don't know much but is it something about oxygen balance or something similar?


texts: How pronounced is the difference if we would change the running direction for runners?

texts:
I was jogging when I asked myself this question:

In running contests the standard running direction is counterclockwise; I also believe to remember that the regulation is very old (right back to the Greeks and Romans). I suppose the reason is that most people have a stronger dominant right leg and running counterclockwise feels more natural.

Now there are people who are "left-legged": They have a stronger and dominant left leg. What I ask is: How would the times change overall if we revert the direction and let the runners run clockwise ? Has someone experimented with it ? Is the effect discernible or even decisive ? Would left-legged people get an advantage ?


texts:
I'm taking an online bioinformatics class and I am stuck on a problem. The resources I have found don't help that much. Here is the problem:

"Assemble the error-free reads from a circular genome on the dataset below. You do not need to consider the reverse complement of the reads.

Dataset: CGTTCT CTAG GACGT TAGAC

As the reads do not have the same length, convert the reads to 4-mers using the approach proposed by Idury and Waterman."

I believe this means I need to convert this into sets of 4 characters each. Do I simply break them up by taking the first 4 characters and last 4 characters like this?

CGTTCT: CGTT --> TTCT
CTAG: CTAG --> CTAG
GACGT: GACG --> ACGT
TAGAC: TAGA --> AGAC

And end up with a new dataset of: "CGTT TTCT CTAG GACG ACGT TAGA AGAC"?

Or is there more to it than that? Thanks for any help.


texts: How to check if a population density obeys replicator dynamics

texts:
Say we have a probability vector or population density $p = (p_1,...,p_n)$ with $p_i \geq 0$ and $\sum_i p_i =1$. Also assume we know the functions $g=(g_1,...,g_n)$ such that:

$$p_i(t+1) = g_i(p(t))$$

where $t$ is a discrete time index. Is there a way to check whether $g$ implements a discrete time replicator equation? I.e. whether there is a function $f=(f_1,...,f_n)$, called the fitness landscape, such that:

$$p_i(t+1)= \frac{f_i(p(t))}{\langle f \rangle_{p(t)}} p_i(t).$$

where $\langle f \rangle_{p(t)}:=\sum_j p_j(t) f_j(p(t))$ is the average fitness of the population density.
Pluggin in $g_i(p(t))$ gives an equation that we could try to solve for $f$ but I don't know how:

$$g_i(p(t)) = \frac{f_i(p(t))}{\langle f \rangle_{p(t)}} p_i(t)$$

or equivalently:

$$\frac{g_i(p(t))}{p_i(t)} = \frac{f_i(p(t))}{\langle f \rangle_{p(t)}}.$$

We can of course also drop the time dependency and write:

$$\frac{g_i(p)}{p_i} = \frac{f_i(p)}{\langle f \rangle_{p}}.$$

Is there a (in the best case necessary and sufficient) criterion that has to be satisfied for this equation to have a solution?
I am also grateful for tips how to tackle this problem in a principled way, including numerically.


texts: How many plants are needed to survive in an airtight chamber?

texts:
How large a garden do you need if you are to survive on them producing enough oxygen in a closed chamber?

And which are the most effective plants?


texts: Are there animal species that sense infrared light with their eyes?

texts:
I asked a question earlier today about birds with infrared vision but this time I am asking about animals in general. I know that many snakes have receptors between their eyes and their snout that allows them to sense infrared radiation but I am looking for an animal that actually uses its eyes.

Googling and searching around found me this statement:

  It's worth noting that, though there are numerous animals that sense
  infrared light, relatively few of them sense it with their eyes

The article didn't list any specific animal that used its eyes to sense infrared light, it just says 'very few'. However, I haven't been able to find any species that can sense infrared light with their eyes.


texts: If I put a cup over a spider, and leave it there for a day, will the spider survive?

texts:
Will it travel more slowly since it hasn't had food for a day?

What if I left the cup there for longer?


texts: Can you think of collective and swarm behaviors as "intelligence"? Would such a concept apply to a) ant colonies and b) fish swarms?


texts: Calculation of NADPH molecules number needed to reduce a substrate in enzymatic reaction

texts:
I am inquiring if it is just simply possible - as it seems to be - to calculate the number of NADPH molecules needed by an enzyme (let say for example Dihydrofolate Reductase DHFR) to reduce the substrate (FH2 or BH2 for DHFR) to (FH4 or BH4) directly from the apparent enzyme reaction?

In DHFR case, can I simply figure it out that I need two NADPH molecules to reduce (FH2) to (FH4)?

Here is the reaction of reducing FH2 to FH4:

https://upload.wikimedia.org/wikipedia/commons/2/29/DHFRmechanism.png

Or is there anything else to keep in mind?

In the figure in the link, the NADPH transferd Hydride, but where did the positive hydrogen come from?


texts: Protocol for measuring stamina of arthritic mice

texts: I am going to make some mice ill with arthritis. The medicine which I am testing as control is known to cause extreme fatigue. I think I've improved it. I'd like to humanly measure their stamina in the presence of something like morphine. How would I ethically do this?


texts: What is this animal that hides in dustlike structure?

texts:
I'd like help identifying the species of animal in these two photos. There's some dust(or dust-like substance) with something alive inside of it (possibly a larva or I don't really know what to call it). This appeared in a couple of hours in the wall. Please, try to even just guess what this could be (I can't think of anything!). Very odd...
I don't even know what tags I hsould use for this!

Thanks in advance

new photo


texts: Do hermaphrodites have more nerve fibers in their puendal nerve?

texts:
Recently I have been thinking, both the glans penis and the clitoris are the most sensitive parts of the body. They contain a lot of nerve endings. Do hermaphrodites share the nerve fibres between the two organs, or do they have double the regular amount of nerve fibers?

Also, at which point does their nerve branch out? Do they have two sets of dorsal genital nerves coming out of the pudendal nerve or does the same set of dorsal genital nerve go into both organs?


texts: Each Spring, our local health unit begins its campaign of Lyme disease and tick-bite awareness. I was wondering if there has ever been a vaccine available, and if so, what antigen does it target?


texts: What is the role of acetylcholine in blood pressure regulation?

texts: What is the role of acetylcholine in the cardiac cycle and in blood pressure regulation?


texts: Is it fine to state every learned behavior has an innate component ? ie. Behavior X is largely/ mostly laerned with an innate component

texts:
For example human acquisition of language, can we say it is learned, but has an innate component -- because there is a particular structure of the tongue, and perhaps also a specific cognitive ability which is requisite to speaking/ learning a language.

The aforementioned requisites are ones which are reliant on genetics, thus can we say there are innate components to it, even though it is largely, based on experience, as stated in the assertion below.

"The behavior of language acquisition is based on experience, and subject to continual refinement and therefore can be classified as largely learned, however, due to the requisites it also has an innate component to it"


texts:
Today I found out that sunburns can cause fever.

What I don't understand is how/why? In my understanding fever is the side effect of an immune reaction against an intruder, mainly bacteria (though I admit I can be wrong).

Google searches like "can sunburn cause fever" only bring up that it is possible, but not why.


texts:
I am researching the safety of IQOS (THS2.2) for heat-not-burn cigarettes (HEETS).

I am particularly interested in appraising the impact of IQOS/HEETS on CO emission and inhalation.

Is there evidence of this?


texts: Why do our eyes close when we sleep? Is it to relax our eye muscles? How can it be explained from an evolutionary point of view?


texts: Global database for patients with rare and important injuries or disease?

texts:
I was recently reading Christof Koch's The Quest for Consciousness, and several times he mentioned how important some patients with sad and terrible brain injuries were for the understanding of the working of the brain.

It made me wonder how brain researchers as Koch and others find such patients. I expect that only a small number happen to see an expert-brain researcher who understands that this patient could be important for brain research, especially for such people in less developed countries.

More generally, I wonder the same for patients with very rare injuries or diseases, which could potentially be significant for medicin- and biology-research:

  Is there a global database for patients with very rare deseases or injuries, making it possible for medical experts in the field to find them?

Even if the expert can not help the individual person, I imagine that such patients could be very important for future understanding/curing of the injury/disease. I hope to get some literature references or suggestion.


texts: Does anyone know the explanation for branches with different flower colors (see picture)?

texts:
As you can see in the below picture, there's a branch with white-colored flowers, while the rest of the tree has pink flowers.

I googled a number of questions but it is a bit complicated to formulate in a search. Plus I have no background in botany or even biology.


texts: Is there a hormone combination that makes humans grumpy?

texts:
Imagine a typical situation that is likely to give rise to a bad temper within an individual: a person is awoken very early in the morning by a sound of a lawn being mowed next door.

Unlike expected awakening by an alarm clock, such unexpected awakening by a lawn mower is likely to leave the person in a bad temper, feeling grumpy or sulky.

I'm interested if there's a specific hormone or process that makes a person experience the feeling of grumpiness? Is it related to adrenaline and fight or flight instinct?

In other words, can experience of grumpiness be induced under laboratory conditions by using some combination of hormones/drugs?


texts:
It turns out that my work in nonlinear dynamics directly maps to Integrate and Fire models and could even provide a new way to control them (manipulate the firing rates). However, it is unclear to me if my findings are interesting or just old news.

I am looking for literature on the intersection of control and neuroscience. Specifically I am interested in any research, theoretical, experimental or simulation-based that dwells on the control of neural systems.

I am especially interested in any work that takes a mathematical point of view on this issue and on any work that summarises the state of art in this field.

Forgive me is this seems trivial to you, but coming form complex systems theory I did my best and found nothing.


texts:
I am trying to get a good pair (or better yet, library of pairs) of primers that give me one band in WT mice (C57BL/6). Do you know where I could find such a thing?

Alternatively, I thought of just designing a few sets of primers myself for highly-conserved regions. But that's quite a bit of guessing work (what regions, what pairs from what eprimer3 will calculate for me etc.).

So:

Do you know where such a database could be found?
If not, could you help me get started with creating it myself? What specific regions would in your opinion be particularly good for this purpose?


texts:
I need to find master transcription factor(s) regulating secreted proteases in a fungus to be disrupted toward upregulation and overexpresion of extracellular recombinant proteins.
How can I detect transcription factors and preferably master TFs (master regulators) in an organism? Does NGS applicable to find TFs and preferably the novel ones? I know ChIP-seq is used to identify TF binding sites but how about detection of the TFs that bind to these sites?


texts: Do sodium channels keep renewing themselves with new subunits made by genes?

texts:
genes make alpha beta gamma subunits (proteins) to be used in making sodium channels... If I understand correctly? And so, since the genes keep making those subunits, does that mean new sodium channels are continuously being made with those proteins till you die?
In other words, if those genes suddenly stop making the subunits in your 50's or something, your sodium channels will disappear or stop working? (Probably unrealistic, but theoretically...)


texts:
Location: South India

I found this plant beside bus stop.

Side view of the Plant.

Actually, Wikipedia says Hedera canariensis is "native to the Atlantic coast in Canary islands and northern Africa", but it is growing in India, so is it really Hedera canariensis?


texts: Why do plants create enough energy for the entire ecosystem?

texts:
In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.

This got me thinking about why energy flows from one level to the next.  Specifically, why do plants create enough energy for the entire ecosystem?  Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy?


texts: How does an organism know when to stop growing, whether it is already on the outermost layer?

texts:
When a multicellular organism is under its development how does the current outermost layer of cells "know" that they should not divide furthermore, as their bodyplan coded into DNA is already achieved. Is it because of morphogens or something else's work is in the background?

If it is entirely controlled by morpogens, than it would mean, that injecting a given morphogen to the outermost cells, would result in further increase in the organism's size?


texts: How do nuclear receptors locate each other to form a DNA loop?

texts:
Nuclear receptors can influence transcription far up- or downstream from their own binding sites by looping DNA (Rubina et al.; J Mol Bio 2004).

I am not sure how exactly the receptors first attach to the DNA (dimers on each site first or the whole complex on one site), but in any case they will need to attach to one response element, then loop the DNA and bind the other response element. It seems like something that should be obvious, but I cannot stop wondering: How do the receptors locate the other site?

Normally I would simply say: diffusion - it just randomly happens. But I imagine bending DNA in such a way would require a lot of energy; too much to just randomly waste it trying to find another site.


texts: Why don't chromosomes double in S-phase?

texts: DNA doubles in S-phase, but chromosomes don't double in S-phase, in spite of the fact that chromosomes are formed by the condensation of DNA. Why is this so?


texts: What material fills the synaptic cleft? Is it water?

texts: The synaptic cleft is the gap between the pre-synaptic and post-synaptic neurons, and neurotransmitters are transferred between the neurons within this region. What substance exits in this space, is it water? If so, what force makes the neurotransmitters move toward the receptors despite colliding with water molecules?


texts: Why do some cuts leave scars, while others do not?

texts: Last year I got a moderately-deep cut on my finger, and it left a scar. Six months later, the scar is still there. On the other hand, I've had lots of other cuts on my fingers, though none have left scars. Why is this? Is scarring related to the severity of the cut, or something else?


texts: Help understanding cell replication animations

texts:
I often come across these animations about molecular biology showing for example how cell replication works, how virus infection works etc. Take this video as an example

https://www.youtube.com/watch?v=odRyv7V8LAE

HIV virus infects T helper cells using receptors on the cell surface which are cd4 molecule, it binds to the receptors using envelope protein. But the video shows you a little ball with some hooks that attaches to another little ball with other hooks.

I understand this is an useful abstraction, but could someone recommend a book or other materials to a novice like me who would like to understand how this really works? Question is probably too general but I am really interested in basics only. Hopefully someone could help

Thanks


texts:
I found this spider in bathroom. Just wanted to know more about it.

Location : India(South India,Hyderabad)
Temperature : 30°C
Humidity : 74%


texts:
Can anyone identify this large fly?

I encountered it in Okefenokee Swamp (Georgia, U.S.A.) on May 1, 2015.
Weather: 53-78°F (avg. 66°F), avg humidity = 60, dew point = 47°F.

The fly was about the size of an adult thumb (more accurately approx. 5cm long and 2cm wide) -- this fly was HUGE! It was fairly docile and allowed me to take a good close-up or 2.


texts: When I took a course on genetics and evolution, I learned that recombination and sexual reproduction is advantageous compared to asexual reproduction. Sexual reproduction allows more combinations of DNA because of recombination, allowing more variations of species, causing natural selection to "choose" different variations of species to reproduce and share their genes to help the species from dying out. On the other hand, asexual reproduction doesn't allow recombination. So species can only rely on mutational changes to keep a species safe from extinction. Therefore, why don't we see more sexually reproducing species than asexually reproducing species? Sexually reproducing species have an advantage, don't they?


texts: Using autoclaved store-bought distilled water for labwork?

texts:
I'm a high school student who's working on a molecular biology project in my school's lab. I need pure water for making culture media, buffers, running a BCA protein assay, running digests, cleaning glassware, etc. I don't have easy access to any professional lab equipment, so I'm looking for an easy way to get "lab-grade" water.

Ideally I'd go to a university and fill up a carboy using a lab's milli-Q system, but this is not easy for me. I also don't want to shell out $$$ to buy ultra-pure water from online suppliers.

Will autoclaving store-bought distilled water (NOT mineral or spring water), suffice for microbiology labwork that needs pure water?


texts:
I am not a biologist

but I wonder if there is any benefit for the human to have hearts on the left side?

do animals have their hearts on the left too? or on the right?


texts:
Are there any mammals in which polyspermy produces viable zygotes? In the wikipedia page it is mentioned that there is a delicate equilibrium between female defenses against many sperms, which ocassionally results in low fertility rates (which in not all cases might be an evolutionary disadvantage, but i disgress)

My question is if there are cases where a ovum can be fertilized by several sperms, and the zygote somehow manages to select fairly between a subset of all chromosomes, avoiding polyploidy and producing a viable embryo.


texts: I'm searching for the mammal species that can produce the most milk during lactation. I Googled it, but it says dairy cattle which biologically speaking is not right answer, because a baby whale can drink up to 150 gallons (> 550 litres) of milk per day (according to whalefacts.org). So which mammal can produce the most milk?


texts:
this is my first message here. Let me tell you why I came to this stackexchange:

A couple of years ago, I took an empty transparent jar (5 liters) and put in it some water (taken from a pond), some dirt and some randomly chosen acquarium-plant. And waited. It was (still is) an amazing experience! The jar went through a number of phases but is still alive, very green, surviving well without any maintainance for more than 2 years (maybe I have added 1-2 liters during this period of time, due to some very low evaporation).

Recently, a friend gave me as a gift a small 15liter acquarium and I decided to do another experiment of this kind. The larger acquarium (compared to the 5L jar) will also give me the possibility to observe better the environment and it's evolution.

Now 2-3 months have passed. The water is still quite yellow-ish, but from previous experience with the jar this has to be expected for the first year or so. [the jar became transparent/green from yellow all of a sudden after about 1 year of life]

However the jar is full of life, the plants are doing fine and there are a lot of little creatures.

QUESTION: could you help me identify one of these creatures? It is a very very small one and I'd like to know more about it.
In this video you can see a number of them going around a small piece of cotton that fall down in the acquarium yesterday.

LINK: https://www.dropbox.com/s/jrkoa5kswghiizm/Video%2011-01-2018%2012%2037%2055.mov?dl=0

thanks for any suggestion!


texts: What is the function of cystine, cysteine, and cysteine protease?

texts:
I am not a biologist, and I have a probably dumb biological question. For some purpose, I need to understand the function of the CTNS gene, and here is the definition of it:

"This gene encodes a seven-transmembrane domain protein that functions to transport cystine out of lysosomes.

I did not know what cystine is, and when I checked Wikipedia, I see that "Cystine is the oxidized dimer form of the amino acid cysteine."

What I understand is lysosomes digest a bigger peptide, and cystine is created as a result, and it is taken out of lysosomes by the enzyme produced thanks to the gene CTNS. My question is, where does cystine go and what is it used for after leaving lysosomes? And is it ever broken further into monomers of cysteine?

I also read about a term "cysteine protease". What is its relation to cystine?


texts: How do migrating geese handle hurricanes?

texts:
I live on the East coast of the United States, where we are in hurricane season. This week during my morning bike rides in Charlotte, North Carolina, I have seen migrating Canadian geese.

I'm curious if migrating geese have any adaptations for sensing and dealing with hurricanes? Do they treat it like any other rain and wait it out or are there observations of them avoiding a storm?

Here is the range of the Canada Goose.


texts:
In the light reactions of photosynthesis, Photosystem I receives electrons from the ETC after Photosystem II sends them to the ETC. Then, when Photosystem I receives light, the electron becomes excited and passes the electron back to the ETC. This leads me to my question: In the following question, are both $B$ and $E$ correct?

Which of the following are directly associated with photosystem I?
$A)$ harvesting of light energy by ATP
$B)$ receiving electrons from the thylakoid membrane electron transport chain
$C)$ generation of molecular oxygen
$D)$ extraction of hydrogen electrons from the splitting of water
$E)$ passing electrons to the thylakoid membrane electron transport chain


texts: What’s the Difference Between Grass and Sedge?

texts: What’s the difference between grasses and sedges? in terms of anatomy and classification.


texts:
It has always been said that sexual reproduction produces offsprings which are superior to their parents, due to the variations which they acquire causing them to survive better in their environment. That's because we can think of meiosis occurring at some level of their life cycle resulting in the variations in the final offspring.
 But what when we talk about bisexual organisms, might they be plants, animals or any other life form? Can't there be variations in their offsprings if they produce them asexually? It's like when they undergo gamete formation in different male and female structure present in that single parent, they'll surely undergo meiosis(if the parent is not haploid undoubtedly) forming the gametes which are dissimilar in their genetic makeup. When these fertilize, shouldn't they show variations?


texts: Does the ratio between M and L cone cells vary in one indiviual?

texts:
Wikipedia says:

  The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects).

This made me wonder if other people then can perceive colors more or less green/red than me. But then I asked myself why do I perceive all colors similarly for both objects on my sightline and at sides (except 90+° from my sightline horizontally). Is that because the ratio of cone cells is similar on the whole retina (in one individual)?


texts: Why can't the brain and red blood cells use fuels other than glucose?

texts:
The question is rather straight forward: I have always been curious as to why, but cannot find an explanation online.

I can imagine that the mechanism is different for each, but why does brain tissue and red blood cells use specifically and only glucose for energy metabolism?


texts: What are the floating translucent little objects called in the field of view?

texts: Sometimes we see these small translucent shapes moving by when the eyes are open. When the eyes are moved they seem to follow that movement, but with a certain delay, as if they are floating in a thick viscous liquid. What is this phenomenon called?


texts:
I am reading the following paper and I have come across the following statement:

It has been demonstrated that the phosphorylation of histone
H2AX-Ser139 to form γH2AX.

I am not sure what the γ before the gene name H2AX means. Is γ used to indicate that H2AX is phosphorylated? Any insights are appreciated.


texts: Why do humans grow taller than their ancestors?

texts:
I'm taking the Introduction to Genetics And Evolution course and in the first lecture it was said that:

  Evolution in a biological sense is simply a change through time. And very importantly, that is change through time over generations. So for example, the human species, hundreds or thousands of years ago was much shorter than it is today. Over the course of those generations, the human species has grown taller. That change is an evolutionary change.

I'm wondering why we become taller than our ancestors? Now we almost don't fight with other species and can live doing something that doesn't require physical strength. It's more logical to me if we would become shorter.


texts:
I thought that massive changes among organisms are over long periods of time. This is caused by, to my knowledge:

Evolutionary pressure
Natural/artificial selection
Mutations
Genetic drift

Will mutations be the only factor in human change? Will humans change at all over a long time?


texts: Will the sex ratio of chickens become favourable to females?

texts: As male chickens are killed after birth in mass farming. Will being male become a negative evolutionary trait, that is to say will females become more likely as male death is more likely.


texts:
They started mating each other and there are lots of them in our hous. I saw them attached together from their bottom.

They have 6 legs and 2 antennae. They have brown wings. i live in iran, tehran. they are about size of fingertip (or smaller)


texts: Understanding the ECG waveform with respect to Lead Positions

texts:
I am really confused about the Representation of potential in an ECG graph.

First i will ask what is on the vertical axis? (I guess it is electrical potential in millivolts)
But again it changes for various positions and the graph takes a different shape. These are called Lead positions ( correct me if i am wrong )
I don't understand why the waveform changes for different Lead positions. Basically I do not understand how the ECG machine works in relation to what happens in the heart ( i.e. the action potentials from SA nodes and so on...)

This diagram shows what I meant.
How am I supposed to interpret the data if it is different depending on direction.

I will be grateful if someone can also provide some information on the cardinal directions in these cases.

Thanks!


texts: How can we determine the polarity of fat molecules?

texts:
I'm trying to solve a question in a biochemistry quiz, which is asking for classifying a set of lipidic derivatives, by increasing polarity. Unfortunately, we didn't cover the classification of different liposoluble molecules by polarity in Biochemistry class. I find myself buried in details every time I use google seeking a good explanation. So:

How can we determine either if one molecule is more/less polar than other ?

  For example, classifying Cholesterol, Triglyceride, Phosphatidylcholine, Phosphatidylserine, by increasing polarity.

PS : I'm not searching for the answer of that example too. I just need the exact method for determining how strong a polar fat molecule is. I'm sorry for my bad english.


texts: Does anyone know of an open repository of medical images (e.g., CT scans) organized by disease category? I'm working on some computer vision software that requires a large set of controls from which to learn.


texts: Why do plants have pith and how is it useful to them?

texts: Many plants have pith, from walnut trees to corn to ragweed, but I can't think of anything it does them. What is pith and how is it useful to them?


texts: negatively charged albumin as major carrier of acidic/negative charged drugs in blood

texts:
I reading that orsomucoid (alpha-1-acid glycoprotein) is the major carrier of positively charged (basic) drugs in the blood, while albumin carries negatively charged (acidic) and drugs with neutral charge.

On the other hand I've read that albumin is excluded by the basement membrane in the glomeruli, and in general by negatively charged glycosaminoglycans in the interstitial space, because albumin is negatively charged.

I did a quick search online and I couldn't find the information explaining this contradiction. Does anyone have an explaination?


texts: Question: What is CINWntUp and CINnormL?

texts:
What is CINWntUp and CINnormL?

I read a paper that uses this two things as classes but Im not sure what they represent. I imply that CIN is referring to Chromosomal instability but I don't know what WntUp & normL refer to. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4214593/)


texts: I need to inoculate spores into milk and then count on the plate. I never see a spore, so how i recognize it from the germ cell? does anyone know the procedure and if there are differences from a normal count in agar colonies?


texts: Why are synthetic Auxins capable of killing dicots such as weeds at high concentration but do not cause damage to monocots?

texts: I read that synthetic auxins like 2,4-D and 2,4,5-T can be used as herbicides against dicots but they don't affect monocots. Can someone explain how they damage dicots and not damage monocots


texts: What is an explanation of the dual role of calcium hydroxide in teeth?

texts: Calcium hydroxide induces dentine formation in permanent teeth, while it causes resorption of tooth in deciduous teeth. How is this dual role explained?


texts: The success of the head transplant surgery depends on the acceptance of the immune cells of the body on which the head is going to be inserted. Can stem cells from thymus gland and bone marrow of the head donor be transplanted into the body on which the head is going to joined, then those stem cells will produce lymphocytes which will accept the transplanted head. Can this be a way to increase the probability of success of the head transplant operation?


texts: Why is centriacinar emphysema more common in the upper lobes compared to the lower lobes?

texts:
I suspect it's because the upper lobes get less ventilated (the volume of their alveoli change less during respiration, and they receive less new air with each breath) compared to the lower lobes, and this causes air to stagnate there more in comparison. Since centriacinar emphysema is usually smoking related, I assume it's because smoke remains in the upper lobes more. I feel like this doesn't really make sense, could be because it's incorrect or it just needs a change of wording.

Also, an extra question if it's okay, why is panacinar emphysema more predominant in the lower lobes? Is it because the lower lobes get better perfusion?


texts: Where can I find histograms and tables of prevalence of mutations in cancer?

texts:
At some point in the past I found a cancer portal site which had aggregated data for the relationships between various mutations and their prevalence in cancer types and tumor data. The data was presented in various pleasantly coloured interactive histograms and you could search per-gene or per-disease.

However after spending a few hours, I cannot find the site again. Though I have found many sites with a great deal of data and nice visualizations.

The nearest looking site, was this one:
http://plugins.biogps.org/data_chart/data_chart.cgi?id=673

But that doesn't have the level of detail that I remember.


texts: Measure of diversity, accounting for known species

texts:
I'm interested in measuring the diversity of each sample out of many independent samples. I know a priori all possible species that could appear in a sample, and expect the counts of species to be from 0 to about 10, although often times there will be none of a particular species within a sample. For example, some data might look like:

Sample # | Species A | Species B | Species C
--------------------------------------------------
1          0           4           0
2          1           1           1
3          0           1           1
4          2           2           2
5          0           1           0

The most diverse sample here is #4. The least is #5. Theoretically, #5 would also be the least diverse ever encountered (assuming there is at least one of some species in each sample).

I encountered trouble when using Simpson's Index of Diversity since that formula would make the diversities of Sample 2 and Sample 3 both 1.0. Intuitively, with this data, I am confident that #2 is more diverse. This is because I know all possible species that may show up.

I'm relying on this definition:
$$
D = \frac{\sum n(n-1)}{N(N-1)}
$$

Are there measures of diversity which account for a priori knowledge of possible species (and perhaps their bounds) and expect near-zero counts?


texts: phosphorous availability to mycorrhizae and parent plant, timing - paper search

texts:
I'm researching phosphorous uptake in monocots to develop planting mixes for riparian planting.

I recently saw a paper suggesting (the author lacked proof) that root zone mycorrhizae may solubilize phosphorous from the soil solution out of phase with the parent plant's ability to take up the phosphate, resulting in P loss from the system. Sadly I didn't save the paper and so it is still out there on the net. If this is the true, and the loss significant, then it would be an argument against using mycorrhizal plants in stream-side planting.

Does this ring a bell with anyone? Failing that, what is known about the relative phasing of mycorrhizal phosphorous release and timing of plant uptake, especially in monocots?


texts:
I often see pictures of turtles riding alligators, I even saw that in a zoo once, but why do they do that?

Is it some sort of camouflage technique for the turtles? And why doesn't the alligator get it off?


texts: Can animals use the nitrogen in chitin to build proteins?

texts:
Fungi and insects contain chitin, which is about 6% nitrogen.
Can an animal - like me - make use of this as a nitrogen source to build proteins?

Are there any animals that can do this?

Are there other uses an animal can put Nitrogen from this specific source to?


texts: What is the number density of fungal spores per unit of volume of air?

texts:
Fungal spores are present all over in the air around us. I understand that they generally range in size from about one to one-hundred microns.

What is the number density of fungal spores in air on a volume basis? I imagine this will vary based on location, season, and indoor vs. outdoor. An ideal answer would account for all of this in the ranges but I'm broadly interested in indoor air conditions around the world.

If measurements of a single spore density are too difficult, I would find the density of CFUs to be acceptable (assuming that those are multiple spores) but would appreciate being directed to information on how many spores typically make up one CFU. Similarly, a mass density of spores would be acceptable as well if experimental methods make that easier. At the simplest level, I'm just curious how much fungal spore material is in the indoor air around us.


texts: Problems with analysis of small RNAseq data - Adapter trimming

texts:
I have always faced a problem while analyzing small RNAseq data, at the step of adapter trimming.

Overview of small RNAseq (Illumina)

RNA is size fractionated using columns or PAGE
3' and 5' adapter ligation
cDNA synthesis
PCR amplification
Sequencing

The length of the reads is dependent on the machine and recent ones like HiSeq can provide ~200bp.

The problem, however, is with reads smaller than the max read length of the machine and this is common with small RNAs such as miRNAs (especially if the concatemer of smallRNA and the complete 3'adapter is bigger than the max read length).

The first step of analysis is trimming of the 3' adapter (Illumina Truseq: TCGTATGCCGTCTTCTGCTTGT).

Several algorithms are available to do this job and what they precisely do is to check for overlaps between the adapter sequence and 3'end of the reads and then clip the aligned region.

Now the problem is this

You can't be really sure of very small alignments because they may not really be originating from the adapters, which means that you should specify a lower limit of alignment for clipping. I usually set it as 5 (intuitively).

But if a small piece of sequence really came from the adapter then it will remain and there is no way to clip it without any doubt.

The real problem comes during aligning the reads to the reference sequence. Aligners like bowtie (which i prefer to use), generally have user defined argument for number of allowed mismatches. Bowtie generally doesn't perform very well if you allow a lots of mismatches.

Subsequently, you might lose a really valuable read.

Alternative

To avoid this problem I sometimes trim the reads to around 25nt (for miRNA profiling). This creates a new problem:

You can't really distinguish whether the read came from a pre-miRNA (a longer RNA) or from mature-miRNA (smaller RNA that arises by processing of pre-miRNA)

Does anyone have an experience or an idea about how to solve this problem?


texts: How are cardiac cells stimulated by an action potential?

texts: Why, and how, does the action potential of one cell in the heart stimulate an action potential in the next cell? I'm interested in an answer with citation.


texts: I got this green plant as a gift many years ago, but I have never seen it flower before. It has a strong, pleasant scent and cool flowers so I'd really would like to know what it is.


texts: What are the distinctive structural features of single- or double-stranded xRNA, or where can I find them?

texts:
I am interested in the structural differences caused by benzopurines and benzopyrimidines at the oligonucleotide level between RNA and xRNA, both in single-stranded and double-stranded form.

I am aware of RNA's tendency to be found in the A-form, of which the details are found here. However, other than the obvious nucleobase expansion, I can't seem to find any details about xRNA's secondary structure.


texts: c4 cycle in photosynthesis occurs in monocots or dicots

texts:
the biosynthetic  portion of the c4 cycle occurs in the bundle sheath cells and i have studies that bundle sheath cells are present only in dicots and not monocots.
according to this, the c4 cycle shold be occuring in dicots and not monocots (due to the absence of bundle s. cells).
but important examples of pants following the c4 pathway like maize and sorghum are monocots.

i dont understand if there is a confusion on my side regarding presence of bs cells in dicots or if there is somewhere else that im going wrong.the following link is contradicting my answer as to presnce of bs cells in dicots


texts: Left Ventricle vs. Right Ventricle size in different Animals

texts: Why are the right ventricles in chicken hearts significantly smaller than the left ventricles, whereas in cows the two ventricles are of roughly equal size.


texts: My daughter is studying in 4 the std. She is interested in species related study. Pls guide her.


texts: Which three functional groups are found in the general structure of amino acids?

texts:
Yes, I know, not two, but THREE.

EDIT: Yes, sorry but I did quite a bit of research, searching my notes and textbook for the answer, but all I could find was TWO functional groups as a opposed to the three my guide said there should be. Trust me, I looked quite a bit and there were many conflicting sources with different answers.


texts:
This article

https://www.prnewswire.com/news-releases/smartphone-addiction-creates-imbalance-in-brain-300558945.html

Says both

  The researchers performed MRS exams on the addicted youth prior to and following behavioral therapy and a single MRS study on the control patients to measure levels of gamma aminobutyric acid, or GABA, a neurotransmitter in the brain that inhibits or slows down brain signals

And

  Having too much GABA can result in a number of side effects, including drowsiness and anxiety.

If GABA slows down brain signals, wouldn't that reduce anxiety? And if you have too much GABA, wouldn't that reduce anxiety also, not increase it?

DreamWater, a 5 Hour Energy counterpart, has GABA, 5-HTP, and melatonin, which promote sleep. It wouldn't make sense that GABA increases anxiety to promote sleep.


texts: What determines the differences between differentiated cells?

texts:
Given two multi-cellular species with obviously different phenotypes. The reason for the different phenotypes reflects their different DNA.

However two types of cells in an adult organism may have clearly different phenotypes (e.g. morphology), but the same DNA, with a different set of genes expressed.

To explain this it would seem that there must be some molecules to modulate the expression of the DNA in different cell types. In my reading I have found one such type of molecules the presence of which is prerequisite for one type of differentiation – modification of histons – methyl, phosphate, acetyl, ubiquitin. Another class of molecules is the transcription factors.

My question:

What would one look at to tell the differentiated type of a cell (ignoring its phenotype)?

Addendum: After having delved a little bit deeper into the topic of epigenetics, I'd like to suggest as a possible answer: it's the histone code one has to look at, something like: how the DNA is wrapped around which sequence (!) of (modified) histones.


texts: Hair becoming white in one night after tremendous stress

texts:
You have surely heard about soldiers during the war whose hair became white in one night due to the tremendous stress.

I was wondering how is this possible biologically ?


texts: What kind of spider is this?(Rajasthan, India)

texts: Hi there, I found this insect in India/Rajasthan. Is this a spider or scorpion? It was nearly 50 mm in length.


texts: My friend's father has diabetes (who was diagnosed with diabetes long after my friend's  birth). The doctor told the friend that he has more chances of getting diabetes than a normal person and he must make lifestyle changes as he is more likely to get the disease. Does it mean that diabetes is genetic (hereditary)?


texts: Why do some animals have 8 Limbs (e.g. Spiders, Octopuses)?

texts:
Octopuses have 8 tentacles, spiders have 8 legs.

Is there something special about 8? It seems like an animal that needs 360° mobility has 8 legs.


texts: Antibiotic resistance of Staphylococcus epidermidis and S. warneri

texts: I am looking for information regarding the antibiotic resistance of S. epidermidis and S. warneri, specifically against penicillin, ampicillin and tetracycline but to no avail. Are there any good websites with databases where this information is shared?


texts: Are human disease-causing organisms living in other creatures helpful to them?

texts:
There are many examples of this.

How is rabies helpful to a dog?
How are Zika virus & Malaria helpful to a Mosquito?


texts:
On hot summer nights we get flocks of ants that have grown wings (from what I know to migrate nests).

It appears the wings are not permanent, but are grown for a temporary purpose.

From what I know these events are triggered by climatic conditions (warm evenings).

In other species, wings seem like a really big deal and are grown from birth - wheras ants seem to just grow them 'on the spur of the moment'.

My question is How do ants spontaneously grow wings? Are they a spare layer of skin that is normally discarded and only comes into action when necessary?


texts: What kind of beetle is this? (Black and yellow)

texts: Found this in my house in Colorado. I took this picture before releasing it. I didn't measure it, but the diameter of the cup it is trapped under is about 5.5 cm, so that makes it about 1.1 cm long. It easily climbed up the side of the glass cup.


texts: How are sequential patterns grouped into meaningful objects in the brain?

texts:
The background how I came up with this question derives from information theory so I am not sure that it will formulate it well.

What I am looking for it is the process how our brain forms patterns.
Lets say I have word “Hello” (It is a complex example, but lets say that our brain is blank and sees it for the first time and somehow it can form only this pattern).

How our brain (neurons, synapse connections) “knows” that certain signals should be grouped and after “H” waits for “e” and “l” and so on.

Why it makes certain connection or just “cuts” and waits for new one.

As our brain is so complex, I am not looking for all scenarios how in could be influenced in terms of chemical neurotransmission, but I am looking for a basic principle of how it is done, i.e., how our brain manages to translate patterns into certain connections inside the brain.


texts: I found this larva (assuming it is a larva) when my cat jumped off my bed, I'm assuming she just picked it up outside. However, I'm not quite sure what it is or if it should be a concern she had it on her. When it moved, the tip of the "head" looked black and it did have "feet" like a caterpillar. If it helps, I live near middle TN and the approximate size was about an inch long. I took some pictures found below, if anyone has any information on it, thank you!


texts: During periods of rain/showers, does the transpiration process in plants slow down as a result of an equilibrium of water in the interior and on exterior of a plants foliage?


texts:
My cat has been messing with that insects. It looks quite unusual.

Anybody here can help me identify it, so I can make sure it's not dangerous?

Location: Israel


texts: Why do I hear beatings with stereo headphones?

texts:
When I play a sine wave together with another pitch shifted sine wave I hear the beating very clearly. This is the expected physical phenomenon.

When I use headphones to play the lower frequency sine wave in my left ear and the slightly higher frequency sine wave in my right (or vice versa), there should be no way for them to physically interfere with each other? But I still hear the beatings, just less strongly.

I tested it with a few different people and how strongly one perceives the beatings varies between people, but many do still hear it. Why?


texts: RNA migrating slower than DNA on Formaldehyde Gel?

texts:
So I ran into an interesting problem.  I'm getting a linear DNA band that is twice as long (4x bases, but as denatured probably only 2x) as an RNA band running at the same size in a formaldehyde gel.

Both sequences have been isolated an 100% confirmed.  The gel was run in MOPS buffer.  My experience, and all the publications I've found, show that if anything RNA should run faster.  Can anyone think of a reason why the DNA band and RNA band would be running the distance despite the DNA being twice as long?

I've read a lot of fun papers on drag factors in gel matrices now, but none of it leads to this confusing and repeated result.

Edit: Gel and Conditions

Gel was 1M formaldehyde, 1% agarose.  Run at 100V for 1.5h.  RNA was mixed in a RNA loading dye which contained 15.3% v/v formaldehyde, 41.3% v/v di formamide, 4.6mM EDTA, MOPS, and bromophenol blue.  We believe our RNA loading dye to be denaturing, and it ran at expected size with RNA ladder.

................(1)........................(2)............................(3)

Lane 1 is a DNA template plasmid, cut 1 location.

Lane 2 is the Template + DNase from in vitro transcription reaction w/o polymerase.

Lane 3 is the RNA + DNase from in vitro transcription reaction.

There are no other bands in the DNA lane, and it looks like if anything, the DNA is migrating much faster than expected, despite being sequence confirmed (both before the process, and gel purified out and confirmed again).


texts:
Here is the thing. I am using a method, called TU-Tagging, to isolate cell type specific RNA. You can find more about the method here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2783170/

To explain it very briefly, there is an enzyme called UPRT (Uracil Phosphoribosyltransferase) which is expressed in Toxoplasma gondii. Under normal circumstances UPRT creates UMP from host cells' uracil and this UMP incorporated in RNA. However, they found that this enzyme cannot distinguish uracil and uracil analog 4-Thiouracil (Basically has thio on 4th position of the uracil). So, when 4-TU provided externally, UPRT incorporates 4-TU into RNA and you get thio-RNA. Then with basic biotinylation and streptaividin isolation you can get thio-RNA from your total RNA isolate. (Of course UPRT should be put to specific cell types of your interest)

Anyway, after the explanation (maybe it was unnecessary though) here is my question.

After I isolate my so called specific RNA, I check the purity by qPCR by using cell type specific markers. I do not have a reference gene. The only thing I am interested in is the presence or absence of markers (and also the fold change of course). Now, I have some data but I do not know how to present them (There is nobody in my lab experienced with qPCR and my experience is just so limited).

Do you have an idea how I can overcome this issue? I looked into some calculations but most of them are needed for reference genes or some other stuff. The only thing that I have is cycle numbers and my primers' efficiency. Do you think I can do something with these inputs? (I know that cycle numbers mean nothing in a plot, so I do not want to put cycle numbers basically.)

Thank you for reading it. Any help/idea would be very appreciated. I am so desperate. Thank you.


texts: What is this plant with some seeds around its leaf?

texts:
I am in India, This plant is growing on floor with very less soil
on it. I took 3 pictures of the same plant, It just rained yesterday.
I didn't see any insects around this plant. here is it:


texts: Is it possible that a set of functionally related proteins in a pathway fulfill different functions?

texts:
Could it be that a given pathway of enzymes (or proteins in general) may fulfill different purposes in a cell by for shifting partners? Say protein A activates B, B activates C and C has a specific action X (e.g. X = phosphorylation of protein D). Now do pathways exist where, e.g., A can activate C directly resulting in action Y (e.g. dephosphorylation of protein D)?

At this time I am in need of real-world examples of this scenario, but I can't find any. Can anyone help?


texts: Calculating the human carrying capacity for turtle tours?

texts: I am looking to calculate the human carrying capacity of a leatherback nesting beach in the Caribbean to inform conservation policy on the maximum number of people allowed on turtle tours; yet after an exhaustive search, I have found very little. Could anyone point me towards a research article that could be of assistance?


texts: Is it possible and how could it possible for plant to survive in naked space

texts:
I heard that there are fungi could survive on space station in the naked space. I want to know if any plant could be able to do the same

How many limitation of plant differ from fungi

And could it possible for them really grow with photosynthesis from the sun. At least growing out of space station which we may fed them with our carbon and water but not limited to only inside of our shell


texts: I recently read about a fossil called Opabinia. What intrigues me is that it had five eyes. I was under the impression that most features, such as eyes, ears and legs are always even-numbered, i.e., 2, 4, 6 etc. Why did Opabinia have 5 eyes?


texts:
I know that if I am dealing with a diploid case, and I have 3 alleles, then I can have 6 possible genotypes. I am doing this by adding up all the numbers from 1 to 3. $$1+2+3 = 6$$
But if I want to generalize this, say for a pentaploid, how do I effectively compute the number of distinct possible genotypes? (Assuming perfect HW equilibrium)

I want to say this is just a simple problem of combination with replacement, but I'm not sure if the biology allows me to make this statement.


texts: Is the empty GI tract a hollow tube with air inside, or is it generally collapsed until food is eaten?

texts:
I have heard that "air in the GI tract" results in flatulence and burping etc, however I initially assumed that the "empty" GI tract was a hollow tube filled with air anyway.

So on an empty stomach (or "empty" GI tract rather), does the GI tract collapse due to the pressure in the surrounding cavities, or is the GI tract normally a hollow tube filled with air, and flatulence merely a result of "excess" air?


texts: What is the name of this small black insect?


texts: What insect would make a hole and lay eggs in it

texts:
Does anyone here have an idea what insect would make a 1-2mm hole in a grape vine cane, and lay small white/clear eggs?

Holes in cane:


texts: Blood circulation and blood pressure in different tissues

texts:
The volume of blood coursing the blood circulation is approximately five litres. A typical vein will stretch about eight times as much as corresponding artery. Because veins have high capacitance, large changes in blood volume have little effect on arterial blood pressure.
If the volume rise or falls, the elastic walls stretch or recoil, changing the volume of blood thus blood pressure in the nervous system.

What else tissues can we consider?
I am interested in blood circulation and blood pressures in different tissues.


texts: Is there something amounting to "check sums" in genetic code?

texts:
Humans use checksums for many different applications in informational processes.
Genetic code is used as a "program" to synthesize proteins, so it could (I'm a layman when it comes to biology!) make sense that its integrity is protected in some way. And since there are just so many cells in a human body a few "retries" could be attempted when encountering bad strands in one source during DNA replication or protein biosynthesis.
Because minute mutations can have a big effect, I was wondering if there is any mechanism that amounts to check sums in genetic code? And if (no) such thing has been discovered as of yet, is there any theory as to why (not)?


texts: Is there a clear detailed description for multiallelic genes? Are they simply genes that are more than two alleles?


texts: Are there dextral/sinistral higher animals?

texts:
For example, almost every dog I've met in my life (more than 20 subjects) uses their right paw touching one while asking for attention. Can it be used as a criterion for calling them dextral? If not, what?

However, I realize that even those dogs who live in the street might get influenced by dextral people:

  There is no domestic animal which has so radically altered its whole
  way of living, indeed its whole sphere of interests, that has become
  domestic in so true a sense as the dog (Konrad Lorenz)

Is there any research about it?


texts: Are the bacteria in the stomachs of unborn babies beneficial?

texts:
Babies are born with bacteria in their stomachs. I heard on The radio that when a child is given antibiotics for the first time unique bacteria in the stomach are destroyed and cannot be replaced. Is this true, and, if so, does this have negative effects on the health of the newborn?

Closely Related, but different: What bacteria do unborn babies contain?


texts:
Complete beginner question here, don't laugh:
If I have some primers that have been synthesized, and I am close to running out of them, is there any way to duplicate them / amplify them / synthesize more of them myself? I don't know the sequences.
Or is my only option to buy more?
Thanks


texts: What are the differences between the margins of the lateral and medial condyles of the tibia?

texts:
During an osteology lecture about the bones of the leg, the professor mentioned that the posterior (i think it was the posterior at least, I didn't write my notes down very well) margins of the lateral and tibial platues at the articular surface are different; the medial one's is sharper, and the lateral one's is smoother, rounder, or, as he put it, "sloppier", and this helps give more motility to the lateral meniscus and makes its injuries less likely. It also apparently helps the motion range of the knee joint.

I can't seem to be able to find any article or book that talks about this (I've checked Snell's, Gray's and Grant's anatomy books), so I was wondering if this is really a thing.


texts:
I've attached the picture of the problem.

SO, based on the information I managed to assemble two large cistrons. (if the combination of two mutants yield (-) mutations are on the same chromosome)

A)so my cistrons are:

1)(1,4,5,6,7,9)

2)(2,3,4,7,8,10)

Note: somehow 4 and 7 is present in both cistrons

B) they ask us what mutation could cause two different cistrons have the same mutants

I was thinking maybe an insertion? i just dont get how it's even possible since if they have the same mutants doesnt it mean they overlap and thus are on the same chromosome??

I would appreciate if you could explain me what type mutation could cause it and check if I did the complementation correctly


texts: Pedigree Probability of Autosomal Recessive Trait

texts:
Here is a pedigree:

The trait is autosomal recessive.

The question is:  What is the probability that the bottom 2 people (4 and 5) have a child with the trait?

I tried doing 2/3 * 2/3 * 2/3 *1/4 and got 2/27 but this is wrong. I thought that the probability of III 1 being a carrier is 2/3.  The probability that IV 4 is a carrier is also 2/3.  The probability that III 6 is a carrier is 2/3 and IV 5 must be a carrier.  So IV 4 and IV 5 must be carriers.  The probability that they have a child with the trait is 1/4. But I am not getting the right answer.

The right answer is 1/6.


texts: Insect with Mohawk-style back in Mexico City


texts: What exactly happens during the crossover

texts:
My knowledge of biology is rather limited, but I think I have a grasp of some basic concepts. For me (as a person close to math) a chromosome is a sequence of elements from the set {A,C,T,G} of some (arbitrary?) length. In humans, there are 23 pairs of chromosomes, and during meiosis each of these pairs produces a singe "mixed" chromosome.

Q1 In each pair, do chromosomes have to be of the same length? If yes, does it mean that this length is the same for all humans? Do chromosomes in different pairs have different lenghts?

Now, we have two chromosomes from the first pair and they get mixed during the meiosis.

Q2 In which exactly place do they get mixed?

if chromosomes are same length, I expect they exchange pieces of the same length only as well; however, if they are of different length, do they exchange pieces of different lengths? e.g. suppose first chromosome in a pair has length 100, second is 105 (I do understand that in reality the numbers are much bigger). Can that happen that the new chromosome is created using the first 10 elements of the first, and the last 80 of the second (so the first 10 of the first replace the first 25 of the second), with the total length of 90?
how many exchanges may happen in a single meiosis, namely can that happen that chromosomes exchange several separated pieces from the middle?

I guess, that this process may not be understood completely yet, so I'm rather looking for an answer either "No, it can't happen at all, we know that for sure", or "this we don't know yet, perhaps it may happen".  Thanks.


texts: Why do bacteria adapt quickly to antibiotics but not to much more common threats?

texts:
People cook food all the time, why don't common bacteria adapt to extreme heat? It's winter in either hemisphere every year, why don't common bacteria adapt to extreme cold? People use soap or spray cleaners, why don't bacteria adapt to those chemicals?

Why is it specifically only antibiotics that bacteria adapt to so quickly?


texts: Is there a biological basis for race (re: Nicholas Wade's article)

texts:
I just recently read this article by Nicholas Wade on Time Magazine's website about a biological basis for race.  It all sounded very racist, but of course my Western liberal attitudes about racism shouldn't cloud my stronger Western liberal convictions about Science giving every empirical claim a fair hearing.

So, that said, where can I learn more about the evidence supporting and contradicting this view?  I found on his Wikipedia page that a number of scientists have condemned his work, but I'd like to actually know the evidence and arguments underneath all this.

I suppose I should also ask more generally about the state of biological evidence for the reality of race.  I had heard in college that there is no biological basis for race, but I'm wondering if that is an out-dated view in light of recent work in genomics.  I read this stack exchange question but it had more to do with whether there is a consensus rather than on the arguments surrounding the issue.


texts: What are the chemicals of betel leaves that may react with estrogen?

texts: Im conducting this experiment about pregnancy testers.Im not quite sure what extract method i can use regarding this experiment.any thoughts?? please help me..


texts: Is there a schema for how human behavior is genetically determined?

texts:
It seem one can distinguish three different kinds of genetic determinism of common patterns of human behavior:

behavior that is directly wired into our nervous system, e.g. face-related mirror neurons and chewing,
behavior that is within reach of operand conditioning, i.e. that is predisposed by certain features of our bodies (and environment) and relatively easily discoverable by exploration, e.g. how to throw something,
behavior that is passed on culturally, e.g. tool use.

Does there exist something like this in the literature?


texts: Do all organs of our body secrete hormones?

texts:
My teacher says that all organs of our body secrete some kind of hormone so they are all glands.
Is the statement entirely correct without any exceptions?
Till date I am unable to find any exception for that statement.
Could anybody provide an exception if any present?


texts: Do sulfate reducing bacteria ingest their sulfate as solid, or as dissolved in water?

texts:
Do sulfate reducing bacteria ingest their sulfate as solid, or liquid or gas?

I understand that almost all forms of sulfate are solid.. and sulfate can be dissolved in water(thus no longer solid, but liquid).

So, do sulfate reducing bacteria ingest sulfate in its solid form, or do they require it to be dissolved in water?

A similar question in fact, for nitrifying bacteria, though if that's complex I might make it a separate question.

Also, even though it's respiration(which tends to be associated either with the breathing process - in the case of physiological respiration, or with having breathed prior - in the case of cellular respiration), here it's not using a gas. So i'm curious if biologists ever use the word "breathing" for such a process.  wikipedia for example, says https://en.wikipedia.org/wiki/Sulfate-reducing_bacteria  " In a sense, these organisms "breathe" sulfate.." I wonder if biologists use the term 'breath' in such a general sense(to include consuming a substance dissolved in water), or only in a specific sense of gas or air, or if they don't use the term 'breath' at all. So, how strictly is the term breath defined in biology.


texts: My height, as predicted by my genetics, is 156 cm whereas my actual height is 172 cm. What could be the reasons for this substantial discrepancy? Does it just mean I had very good nutrition as a child?


texts: How does the size of insert affects the rate of Homologous Recombination in yeast?

texts: When performing genetic knockouts in yeast using homologous recombination to replace a target gene sequence via a vector DNA, does the region between the flanking regions in the vector have to be the same length as the site of recombination in the host cell's gene?


texts: Under what conditions do laboratories have the need to perform both, colony counting and cell counting?

texts:
It seems that the requirements to perform colony counting and cell counting in petri dishes are quite different. This is especially true, because colony counting can be done with the naked eye, even though it can get very tiring.

Since I am interested to find out what tasks most biological labs have to go through, I was wondering whether these two tasks might be requested by the same types of labs.


texts: Identify this black dragonfly with bluish coloration along its flat top, yellow on it's mid-body and green on its head

texts:
I took these photos around noon in late July in Hsinchu county Taiwan. This particular stick in this particular pond is visited by many dragonfly species. I have seen this kind of dragonfly very regularly, in different nearby ponds, they seem to me to be far more active than other dragonfly species in the same area at the same time.
Its body is about 5 cm long and mostly black. However it has light "power blue" to white markings on the flat top surface of its "tail" and "mid" sections and the front part of its body before the head, and it seems to have some smaller yellow bands on the sides of its fore body and greenish markings on its head.
Wings are mostly transparent but are tinged orange or brown near the body.
Question: Is it possible to identify this particular species of dragonfly?


texts: Why doesn't enzyme reaction rate rise linearly with substrate concentration?

texts:
This is the graph of the Michaelis-Menten equation which describes the relationship between reaction rate and substrate concentration:

I don't understand why it is hyperbolic. Intuitively, I would think that it would be linear.
Here is my logic for a specific scenario:
Let's say enzyme $E$ converts substrate $S$ at a rate of $1 S$ per second. Now let's say we have a container with 1000 enzyme E's. And there is a tube connected to the container that pumps in $10 S$ per second.
Logically, in the one second, all 10 substrates should be catalyzed. The rate of reaction would be $10/s$. Now if we increase the pump to 500 substrates per second, you would think that all 500 substrates would be catalyzed in one second, making the rate $500/s$. Thus, a linear relationship.
The formula for rate of enzyme-substrate complex formation is also linear:
$$\frac{d[ES]}{dt} = k[E][S]$$
What am I missing here? I am looking for a mechanistic explanation (diffusion, dissociation, etc)
Edit: I've done some more thinking and I have a potential explanation. Could it be that, as the concentration of substrate goes up, the probability of a substrate interacting with an unbound enzyme goes down.
In my scenario, the first substrate has a 1000/1000 chance to find a free enzyme, the second substrate has a 999/1000 chance of finding a free enzyme, etc.


texts: Does denaturing proteins lead to loss of epitopes?

texts:
I am doing an experiment where I have to do both Immunohistochemistry and SDS-PAGE. I am assuming that the native conformation of the protein is maintained in the IHC. But during the blot, we heat the protein (at least in our lab) at 95oC in mercaptoethanol to denature the protein by breaking the disulphide bonds thereby destroying the tertiary structure.

My question is when we are using the same antibody against the protein in the tissue (intact for IHC) and isolated (denatured for SDS-PAGE) protein, how can it bind both? So, the antibodies bind to the epitope based on the AA sequence or the 3D conformation? Wouldn't there be a lot if cross reactivity if it binds just based on sequence (since you could have the same sequence in many proteins, having the same conformation is much less likely)?


texts: Hi I am wondering if we can execute a genome on the sub-cellular level by running it on the computer. What I mean is using the genome as data to examine by having the cells reproduce and see what happens as they grow.


texts: Are trees still carrying their leaves more likely to be felled by an autumn storm?

texts:
Is there evidence that trees still carrying their leaves are more likely to be felled by an autumn storm than trees already having lost their leaves?

At first sight this seems plausible (and might be easily verified statistically), but at second sight it seems mysterious, considering a) the weak forces that keep leaves attached to their branches (at least in autumn times), b) the flexibility of the branches, and c) the chaotic way in which they are shaken by a gust.

Anyway, after storm Xavier which passed Germany and Poland on the 5th and 6th of October, this was spread ("kolportiert") by the media and in private communication:

Is there a thorough biomechanical model which explains whether or why this is true or false, resp. to which extent?

I would suspect that in this model a) eigenfrequencies (of branches, limbs and stem) and b) resonance will play a role.

(This model would give an interesting analogy to the sudden generation of action potentials in neurons (corresponding to the breaking of a limb or stem) by spatio-temporarilly integrating the synaptic inputs (corresponding to the shaken leaves) on the dendritic tree [sic!]. Addendum: There's a great book that brings botanical and neuronal trees together: Giorgio A. Ascoli, Trees of the Brain, Roots of the Mind.)

(Note, that one short gust almost never will fell a tree. It must be a rather long gust, or an appropriately long and/or timed sequence of shorter gusts.)

Addendum: The way how fluttering ion channels (on a very short time scale - grey dots below) give rise to a rhythmic and possibly resonant temporal pattern (on a much longer time scale - red or blue line above) may be compared to the oscillations of the tree as a whole, whose "rhythm" (red) cannot be detected when looking at single leaves fluttering (grey):

See also here.


texts: Need of X or Y chromosome protein after meiosis

texts:
After meiosis each spermatid get either the X chromosome or the Y chromosome. I know that the 4 spermatids formed from 1 spermatogonia are connected by cytoplasm and so the proteins made by X or Y chromosome can be shared by all the 4 cells.

I want to know what proteins made by X or Y chromosome are exclusive to the X or Y chromosome and are needed to convert spermatids to sperms.


texts: If a promoter region of a gene is transcribed, can it get methylated?

texts: Deletion of a transcription termination site can lead to a downstream gene's promoter region being transcribed. What if that portion of the mRNA acts like an siRNA methyltransferase recruiter?


texts: How can normalizing selection (stabilizing selection) be involved in speciation?

texts:
In Mayr's book What Evolution Is, he discusses about normalizing selection in rapidly evolving lineages.

"However, normalizing selection is equally active in rapidly evolving
lineages."

What is meant by "rapidly evolving lineages" and what examples can be found about either the rate of evolution in population where normalizing selection is the dominant evolutionary process or the fact that normalizing selection can lead to speciation. How important is normalizing selection compared to disruptive and directional selection?


texts: Type of plant cell that builds a secondary wall in between two primary walls?

texts: I read that there is this type of pattern in cell wall synthesys. What is the type of cell that does that and in what kind of scenario?


texts: Primer design and BLAST E value stringency

texts:
When searching for misprimings I have been told that an e value that is higher than 0.01 is ok and will produce no significant amounts of mispriming. Yet I searched some and it would seem that the e value threshold limit is dependent upon the "amount of information" in the database.  Indeed I found that some papers cite as values lower than 0.07 to be significant already.

What are the criteria you use at times to judge this issue, and how do I know when to lower or increase my stringency when running a routine BLAST for the purposes of designing primers?


texts: Can we modify plasmids to eliminate antibiotic resistance?

texts:
This is a very general question regarding the potential use of artificially modified plasmids to block or modify bacterial evolution in order to prevent development of anti-biotic resistance.

For example the most crude example might be to modify a suitable plasmid with some gift for target bacteria but also to add a mechanism to block their pili after delivering the gift.

If this general principle was practical, there would be huge scope for ingenious biologists to create a plethora of ideas to modify bacteria is many ways to our advantage, even to the extent of creating completely artificial plasmids for such purposes.

My question is twofold: Is this likely to be a valid approach for modulating bacterial evolution to our purposes, and if so, is there already research in progress in this field?

Of course, in the example above, the gift from the plasmid must significantly benefit the plasmid and the poison mechanism must be delayed long enough for a large % of the biofilm-bound bacteria to be infected by the poison before it takes effect. Also the plasmids must include their own slow-acting poison/fast acting antidote to deal with reproducing cells that do not contain the plasmid. A more subtle approach might be a gift that did not kill the bacteria but modified them to be significantly less virulent.


texts:
In "Molecular Biology of THE CELL" 3rd Edition, 1994, by Alberts, Et al. (Yes I know there is a newer edition)

the question is posed on page 362

  How is each region of the DNA replicated only once?

Two suggestions are offered:

Inhibitor-addition model
Initiation-removal model

Since the 3rd edition of the book is now 24 years old, has the answer been discovered and if so what is it?

I am reading the 3rd edition now because that is what I have and plan to buy the newer 6th edition if a 7th edition will not be out in the next few months. This is for self-study so no need for me to rush or have the latest and greatest info for the first pass of learning as I am only reading.


texts: How widespread in the Animal Kingdom is Aromatization as the Process that Determines an Animal's Sex?

texts:
I shall summarize my lay understanding of my question before going into details. To my lay reading, the sex of a vast diversity of animal kingdom species can be thought of as arising from the extent that the process of Aromatization - the catalyic conversion of testosterone produced by the gonads to oestrogen - happens. This extent of aromatization can be egg temperature determine, or genetically determined.

The German "Aromatase" Wikipedia page makes the following curious, unsubstantiated claim (translation mine, so apologies in advance):

"Aromatase (aka CYP19A1) is the Enzyme that in backboned animals catalyses the conversion from testosterone to oestradiol ....[emphasis mine]"

Which raises the question in the title. My understanding was that the aromatization process as the sex determining process was wider spread in the animal kingdom than backboned animals, at least as wide as chordates. Since the claim is unsubstantiated, i put the question in my title to this community.

Another take on the question: Can anyone give me examples of animals which are not backboned animals and for whom sex is determined by the extent of the aromatization reaction?


texts: Isotype control antibodies in Flow Cytometry

texts:
In a Flow Cytrometry, one can add an Isotype Control Antibody to allow another antibody to bind more specific to the cells.

My question is, how can the Isotype Control Antibody add specificity to the other antibody?
My thought was, that the Isotype Control Antibody binds to all the antibody receptors, but with a "weak" binding. When the other antibody (e.g. CD73) tries to bind, it can make a stronger binding with the CD73 antibody receptor, kicking the Isotype Control Antibody off it.

However i'm entirely not sure this is correct... Could anyone explain how the Isotype Control Antibody helps the other antibody (eg.g CD 73) to bind more specific?


texts: Why do I only breathe out of one nostril?

texts: I was just sitting with my hand next to my nose and I realized that air was only coming out of the right nostril. Why is that? I would think I would use both, it seems much more efficient. Have I always only been breathing out of my right nostril?


texts:
I know the third one in the front row is James Watson.

Does anyone recognize the others?


texts: What is a catalytic domain of an enzyme?

texts: Is this another name for the active site of an enzyme? What does the structure of the catalytic domain of an enzyme look like?


texts: Do ants even breathe? If they don't, how do they stay alive? On what resources do they depend upon to stay alive? How are they different form mammals?


texts: The Operation of tuning in the S1 layer of ventral model

texts:
According to my previous question in ventral Stream pathway and architecture, I want now to get a brief example about how the S1 layer is constructed. In other words, how all the simple units are tuned with the gaussian-Like tuning (for example). I am only interested to get such a cartoon example in step by step how this operation can be achieved in given of inputs (which inputs? and what we mean about these inputs?) in order to obtain the tuned simple units.

We all know that each simple unit is obtained after a tuning operation around their inputs (Subunits) in order to select an optimal output which corresponds to the preferred orientation for such a simple unit.

Moreover, I know that the S1 layer units perform a convolution on regions of the raw input image using gabor filters at different orientations and sizes. The entire population of S1 units represents a convolution map of Gabor filters of different sizes and orientations with the entire raw image (really I didn't understand this point) you can read the subsection 2.2 in this article

The image below contains the image to be recognized by the brain and some simple units obtained after the tuning operation. So what I want is to obtain a brief example which can include the details (step by step) of how the operation of tuning can be achieved.

i didn't understand well the concept. That's why i need a real example with a specific image which can contains all the steps described in my attached image (step by step) because i still don't understand what we mean about inputs x, etc.
So please if anyone can give me a real example with a specific image which can respond briefly to this attached image


texts: Difference between pulse and blood pressure

texts:
I'm a very naive and biologically illiterate person, and from what I've read on the internet I'm not really sure I understand the difference between pulse and blood pressure. I'm guessing for most of you this is trivial so I'm hoping for something clear for someone of my "level".
On a side note, I speak french, and we have two words: pression / tension (artérielle). One of them must be wrong since they mean totally different things and makes things even more confusing.
But from what I could gather, are the next statements correct/accurate or am I completely off?

The blood pressure is the fluid's movement "strength" in the veins (or "arteries", please edit my post with the correct english word)
The "tension" is the force applied on the veins itself, kind of like when you're pulling a rubber band
The pulse is just the wave of blood moving, which creates different tensions over the vein and whose movement is created by the pressure.


texts:
Some papers I have read show carbon accumulation (peat) in wetlands is reduced because of low methane emissions. Why is this the case?

Why does low methane emission reduce carbon accumulation in wetlands?


texts: Can you find the amount of heterozygotes in a pop. from the phenotypes shown in the pop

texts: I know the hardy Weinberg equation but that is for the amount of alleles not the amount of phenotypes. So if there are 600 black(dominant) organisms in the population and 400 green(recessive) organisms. Can you figure out how many of the blacks are actually heterozygous?


texts: How is the role of ethylene in ripening demonstrated in biology (or agriculture) education?

texts:
I want to know what are some typical experiments performed in the course of biology education (or possibly in applied biology education e.g. agricutlure education) to prove to the students (or have them prove to themselves) the autocatalytic role that ethylene plays in ripening. I'm interested in both how ethylene production by plants might be demonstrated/measured as well as the demonstration of the role of ethylene on ripening.

I'm aware of some historical experiments e.g. that of Gane (1934). Is it commonly repeated in biology labs in an educational context today? Or is something else used?

I found a lab manual aimed at Indian "class XII" (I guess that's the terminal year in high-school over there); the experiments aren't well detailed but they suggest keeping a sample in open and one packed in polyethylene, or treating one with ethylene. These aren't exactly quantitative though: no suggestions for measuring anything but by eyeballing/tasting. I guess that's the best on can do with limited resources. I'd like to know about college-level experiments, if there are any.

I also know how ethylene is measured in industrial/pro-lab settings:

  Ethylene
  can be measured successfully with a portable gas chromatograph fitted with a
  photo ionisation detector capable of measuring ethylene to a concentration below
  0.01 uL/L. EASI-1 uses a proprietary ‘nanoporous gold sensor technology’ for
  “accurate real-time measurement of ethylene gas concentrations”. This is licensed
  from Fluid Analytics in USA, which offers a claimed sensitivity to ethylene in
  the air at levels as low as 10 ppb.

There also exist industrial scrubbers for ethylene so the air concentration can be reduced. I don't know if either of these are commonly available on college campuses though, even in biotech or agriculture departments.

(N.B.: I don't care about proving the effect in the kitchen, which is the topic of a question on Skeptics.)


texts: What is this tiny, transparent creature found in my home?

texts:
Found these in my bathroom, everything was literally crawling with them - there were thousands of those on walls, sink, bathtub... I have all surfaces were sprayed with chlorine spray and with bug repellent afterwards. Still these creatures came back same day, although in smaller numbers.

There's not many features I can use to describe this creature aside from:

Size: very tiny, below 1mm; (black strands are beard hair)
They are pale-yellowish and semi-transparent as it's seen on photos provided
Rather slow and they walk aimlessly on all kinds of surfaces
They seem to be coming from cupboard under the sink, where it's warm, moist, dark and there's access to sewage piping shaft

I'm aware photos could be much better, but they were taken with smartphone combined with a lens from a flashlight to enable macrophotography. Not a best tool for that purpose though.

EDIT: Added circles around creature. Please ignore zoom cursor on first image.


texts: Why aren't human babies considered larvae?

texts:
I've seen people who are anti-baby describe babies, or children in general, as human larvae. This is generally done in order to make them seem weird. While I feel like this statement is wrong, I can't quite put my finger on exactly why.

Many definitions of "larva" specify that they must metamorphosize, or go through significant morphological changes on the path to adulthood. However, tadpoles gradually change form, rather than metamorphosizing, and hemimetabolic insects have larval instars that aren't substantially different from adults, aside from being sexually immature and smaller. "Sexually immature and smaller", of course, also describes babies fairly well.

Unfortunately, I'm no biologist and my knowledge of what defines animal young as larval vs. non-larval is rudimentary, at best, so I'm not sure if there's a more precise definition of "larva" than the one I found on wikipedia, which would disqualify human babies. What traits differentiate larva from non-larva, and which of those traits to babies lack?


texts:
My question is about making fake auditory signals. The ear collects sounds from the environment, which are transformed into a neural signal by the hair cells in the inner ear. This signal is sent through the auditory nerve to the to brain, where it is decoded into a hearing sensation.

Now can we make fake signals and feed them into the auditory nerve to bring it to the brain? E.g., instead of the ear collecting sound, could we use an electrical instrument for collecting sound and convert this signal into a neural signal in the auditory nerve?


texts: How does activation of adenylcyclase lead to increased cAMP and diarrhea?

texts:
I am trying find explanation for these mechanisms

  Tox plasmid -> exotoxin (enterotoxin) -> activation of adenylcyclase
  -> \up cAMP enterocytes -> release of H2O, electrolytes in gut lumen -> diarrhea.

Tox plasmid is a toxin generated by the genus enterobacteriaceae.
I read this as that exotoxin Tox activates adenilciclase enzyme (protein) which increases the amount of cyclic AMP in the enterocytes, and releases water and electrocytes into gut lumen consequently resulting in diarrhea.

How does the activation of adenylcyclase lead to increased cAMP heparis and diarrhea?


texts: What term describes insects that must eat protein to reproduce?

texts: I know there is a specific term for insects that need to consume protein to produce viable eggs, as well as a term for those insects that don't need to consume protein to produce viable eggs.


texts: how do I find the number of bp in chromosome 3 by knowing number of bp in chromosome 1?

texts: If i have a number of bp in chromosome 1 for example(298,295,559 bp) can I use this number to find the number of bp in chromosome 3.


texts:
Possible Duplicate:
  HIV Rapid Tests

Can proteins found on the surface of RNA viruses cause infection without the presence of the actual RNA and other components used in the virus?


texts: By what means do "nerve agent" compounds like VX spread through the human body so quickly?

texts:
It has been demonstrated that so-called nerve agents are able to incapacitate and kill a human in only minutes after exposure. One such substance, VX, only requires a few milligrams to contact the skin of a human in order to trigger such a reaction.
I understand that many nerve agents are acetylcholinesterase inhibitors, so they promote a surplus of acetylcholine which causes loss of muscle control due to the inability to "rest."
What I totally fail to understand (or find in my searches), is how such a small drop of e.g. VX is able to cause full-body symptoms. In other words, if a drop of this substance gets on a person's hand, how is it that in 1-2 minutes, they begin to have full-body convulsions, defecate uncontrollably, etc...? I would understand this if the substance was sprayed all over someone, but having a drop in the order of milligrams on an extremity, it's not clear how this triggers such a severe reaction all over the body. I am aware that it gets absorbed through the skin, but otherwise I have no idea what happens after that.
My lack of understanding is partially due to:

(A) Neurotransmitter (acetylcholine, ACh) released from nerve endings binds to receptors (AChRs) on the muscle surface.

Kuo IY, Ehrlich BE. Signaling in muscle contraction. Cold Spring Harb Perspect Biol. 2015;7(2):a006023. Published 2015 Feb 2. doi:10.1101/cshperspect.a006023
How does VX so quickly get to the surfaces and inhibit acetylcholinesterase all over the body? Is it a matter of simple blood circulation after the agent makes its way through the skin and into the blood stream?


texts: What is this colourful insect with a large thorn?

texts: Someone sent me the picture so I don't have a lot of details. Is it a real insect or is it fake?


texts: I think they could be carpenter ants, but not sure.


texts:
Antioxidants reduce damage to tissue (by scavenging the free radicals) and thus may reduce ageing.It is known that Uric acid is a very good antioxidant.

People with gout have excess accumulation of uric acid.

Considering the above information the authors of the book  "Why we get sick?" put up an interesting question : Do people with gout live longer ?

I would like to know if there are any studies done to answer the question.