texts: Cause of a extra vertebra in the human body

texts:
Most people have five vertebrae in their lumbar (lower back) region, which are named L1 to L5. However, some people possess an additional lumbar vertebra located below the L5. This extra vertebra, known as the L6, is called a transitional vertebra. About 10 percent of adults have some form of spinal abnormality caused by genetics, and a sixth lumbar vertebra is among the most common of these abnormalities.

Question- What is the current explanation to why some humans have developed this extra vertebra in the spine?


texts: Do electric eels produce current as they just move about, and how/why?

texts:
https://www.youtube.com/watch?v=y9wktSQdyaE
This video demonstrates how an electric eel can supposedly produce up to 800 watts, and power a Christmas tree, which is very topical (a late Merry Christmas to the Biology community!). The video, sadly, is not very detailed as to how this works.
I was under the impression that electrical discharge was a conscious action on the part of the eel, rather than a natural state for it. But, apparently, the electric eel generates electricity "whenever it moves," as the video's narrator put it? Do electric eels produce electricity subconsciously, just by moving? Surely, though the host lists off the 800 watts of power, it's not constantly producing 800 watts, either?
How do the fish's electrocytes work in this instance, where just lazing about is powering the Christmas tree?


texts: I have a burning question. I have read many articles which say that chewing food properly, therefore longer, till you have a liquid-like texture, is causing you to eat less calories. However, it causes you to absorb more nutrients. If you would eat the same amount of food. Would chewing make a difference in your weight gain/loss?


texts: Why are the grey matter structures of the inferior medial frontal lobe not directly (not via white matter) connected?

texts:
I have recently been trying to understand the three dimensional nature of the brain for a neuroanatomy class. Part of this strategy has included learning about structures such as the falx cerebri, tentorium cerebelli, anterior dural girdle, etc in order to understand the physical barriers that surround different parts of the brain and therefore separate them from one another. For example, the reason that the cerebellum and floor of the occipital lobe are not directly continuous is because of the tentorium cerebelli.

One issue that I have recently come across is understanding why the inferior medial component of the frontal lobe, in the region just anterior to the pituitary gland and optic chiasm, are not directly continuous (i.e. the left cortical hemisphere at this location is not continuous with the right cortical hemisphere). I have attached some photos to clarify my confusion:

As you can from this image, the falx cerebri's anterior extent leaves a small opening (indicated by the red line) that would, presumably, permit grey matter from the left hemisphere to be directly continuous with grey matter from the right hemisphere. However, no such connection exists. This is readily confirmed using an inferior view, such as that indicated in the following picture, boxed in red:

As you can see from the boxed area, the medial inferior cortical grey masses from the left and right hemisphere (which are likely the subgenual division of the anterior cingulate gyrus) are distinctly separate. This separation is clearly not related to the falx cerebri, as the anterior descent of the falx cerebri occurs further in front of this area (as indicated by picture 1).

Could anyone offer an explanation as to why these structures are distinctly NOT continuous at this point? Further, if anyone could confirm whether any part of the cortex exhibits grey-matter-continuity (i.e. not via white matter tracts) between the left and right hemisphere, that would be greatly appreciated.


texts: I am from Egypt, and I found this insect in my house. It's slow when it moves, and I didn't see it fly. It's green (my phone camera didn't get the colors right).


texts: If a human takes antibiotics are all bacteria in the body killed?

texts:
From my basic understanding, antibiotics kill living things, bacteria for example.

Do the antibiotics consumed by a human-being distinguish between what they kill? Or do they just kill every bacteria they find? And if that's the case, which bacteria do antibiotics find or do they find all bacteria in a human's body? Again, if that is the case, does that mean that after taking antibiotics for a certain time that the human body is free of all bacteria?


texts: Can viruses be reintroduced to humans from ice sheets?

texts:
A comment on reddit mockingly say

because the ice is melting away due to global warming, this new virus came out of the melted ice sheets

It has 60+ upvotes and no one replied
Is it possible for viruses that are frozen in ice sheets to reinfect humans when they are melted?


texts: Speed of passive transport of ions in the dendrite

texts:
I tried hard to get them, but I didn't get any numbers. My (subjectively) best Google search was for "speed propagation post-synaptic potential".

My question is:

  How fast are ions transported passively inside the dendritic tree (and soma),
  probably depending on their atomic mass, charge, and of the local geometry?

Especially I want to know when a post-synaptic potential generated x μm away from the axon hillock "arrives" there, i.e. can be detected/summed up with other PSPs. Disregarding all of the eventualities (see above):

  What is the order of magnitude of the speed of passively transported
  ions in the dendritic tree?


texts: How many people's DNA were involved in the compilation of the reference human genome?

texts: I know that the reference human genome is complied from DNA portions from different people, most of whom were European. Do you know how many of them were involved? Do you know which ones were involved? Perhaps scientists like James Watson and George Church's DNA were in the reference genome. Also, I would assume that the NIH funded Human Genome Project's reference genome must be slightly different from the privately funded one.


texts: What is special about the N3 buffer for Qiagen minipreps?

texts: For those who use Qiagen miniprep columns, they may be aware that the P3 buffer is the acetic acid step to neutralize cell lysis. They may also be aware that the Qiagen P3 buffer cannot be interchanged with the proprietary N3 buffer. It is also known that the N3 buffer is particularly unique since it primes the miniprep columns for binding. I was wondering about that priming step and what chemically primes the columns. Would it be appropriate to use QBT buffer to prime the miniprep columns?


texts: If you picked two people in the world at random, sequenced each of their entire genome, and compared their DNA, what would the expected percentage match be?


texts: What are the possible reasons to get extra unrecognized band in agarose gel electrophoresis?

texts:
I ran 0.7% agarose gel electrophoresis of my plasmid DNA sample consisting of GFP vector, using NheI and HindIII restriction enzyme.
I used two types of plasmids, i.e., isolated by miniprep-alkali method, and another isolated by midi prep system (pure) of the same source E. coli.
The 4 and 5 lines show cut and uncut plasmid, respectively, isolated by midi prep system.
The 1, 2, and 3 lines show the 500 bp marker, cut, and uncut of miniprep isolated plasmid signal, respectively. In the attached image, we found an extra band in the plasmids isolated by alkali method (line 2 and 3), but in the pure samples (line 4 and 5) no such extra bands were found.
What are the possible reasons behind the result? How may I interpret this result? If anyone has experienced similar results, please share.


texts: Can ELISA be used to detect a plant enzyme? Creating assay for a new enzyme

texts:
If the goal is to generate a rapid assay for an enzyme of plant source what are the typical options?

i.e. Could one do something like: Generate an antibody to the enzyme and then use it to create an ELISA? Would animal-injection be the way to generate the specific antibody needed?

If not, what is typically done in such cases. How does one go about creating an assay for a new enzyme of plant source. Are there alternative approaches that avoid the antibody creation?


texts: What is the eye muscle status when you stare at distant view through a glass wall?

texts: The book said when you look at object close to you, the eye muscles contract and vice versa. I wonder what will be the status of the eye muscles when I stare at distance view (such as a mountain) inside an office through a glass wall. The mountain is far away but the glass wall is close to us. In this case, does the eye muscles relax?


texts: Can someone please explain the following jargon to a layman

texts:
I was reading an article on a substance called apigenin:

  Apigenin can inhibit both aromatase and 17β-hydroxysteroid dehydrogenase (17β-HSD) with the inhibition of 17β-HSD being unique to apigenin and 3 other tested flavonoids (chrysin, genistein and naringenin)[22] and apigenin possessing an IC50 of 300nM (0.3μM). The IC50 of Apigenin on aromatase is approximately 2.9μM (most potent tested flavonoid on aromatase was 7-Hydroxyflavone at 0.21uM, outperforming the reference aminoglutethimide at 1.2uM[22]) and both of these enzymes are involved in testosterone synthesis at different stages.

Does this mean that higher apigenin potentially yields higher or lower levels of testosterone? I guess I'm unsure what the implication of "inhibits" is.


texts: What are these pathways called in Biology?

texts:
Considering the pentose phosphate pathway and the sulfate reduction pathway in bacteria;

What are these types of reactions called in biology? Bio degradation reactions or bio transformation reactions or something else? I wish to know whether there is a generalized names for these types of pathways.


texts: Removing a restriction site and introducing other at its place

texts:
What would you do if you want to remove an EcoRI restriction site
  and introduce BamHI restriction site at apprx. the same location ?

One of the answers in my textbook was : To construct a DNA fragment with the structure:

5'AATTGGATCC3'
    3'CCTAGGTTAA5'

I understand that this would ligate efficiently to the sticky ends generated by EcoRI cleavage and would introduce a BamHI site but I don't understand how this will remove/not regenerate the EcoRI site.


texts: Does food lose some of its mass in form of energy during metabolism?

texts:
I had an argument with someone.

I argued that when a cat eats 1 kg of food, the sum of subsequent output (poo + pee + sweat + change of body mass) must be equal to 1 kg.

My opponent argued that the output will be less than 1 kg because a part of food is converted into energy.

Please rule.


texts: Peptide hormones for example tend to be secreted by Ca2+ mediated exocytosis following depolarisation and are secreted in vesicles. How are steroid hormones secreted and what stimulates their secretion? Please leave references if possible.


texts: Light signals in the courtship and mating

texts:
I am investigating on the emission of signals in the courtship and mating in the animals.

I know that the fireflies emit light signals as a courtship ritual.

Are there other animals that use this phenomenon of luminescence?


texts: Regarding cancer cells and radio-frequency ablation

texts: Are cancer cells destabilized if near a strong electromagnetic field over a long period of time? I read this technique of using radio-frequency ablation and heat shock to kill cancer cells. I don't know if this is viable but maybe a person could wear a device like a pacemaker right over the area of a tumor that emits  strong E.M. pulses over say a month or a year. Could this destabilize the tumor ?


texts: Can virus resistance be acquired through generational exposure?

texts:
If I have a squash plant that has a mosaic virus of some kind, and I breed its descendants (via seed) for generations, each with exposure to the same virus, will future generations be likely to eventually obtain resistance to the virus, and if so, how long would this typically take?

It seems to me that this might be how the resistant plants would have first developed resistance, but I could be wrong.


texts:
I'm a computer programmer deeply interested in Biology.

I wish to write a computer simulation for cell differentiation. I understand there will be seemingly impossible challenges in doing this. But first I am looking for  answers to some basic questions.

I've learned that a zygote turns into 'embryonic stem cells' which results in the organism. How does the zygote turn into embryonic cells ?
What are the factors that determine the specialization of embryonic stem cells into more specialized types of cells and how does this transformation take place physically ?
Where is the data stored which acts as the "guide" for all these processes ? Is it stored in the DNA ? If it's stored in the DNA , is it known how the cells interpret the information in the DNA?
What are some textbooks I should be referring for this project ?

PS : Pardon my ignorance if these questions sound stupid, but I'm willing to commit time for learning anything needed to do this. Also , I understand all these questions cannot be answered in a few lines. Please provide references/pointers . Thanks !


texts:
Chargaff's rules states that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.

As in the table $A \ne T$ and $C \ne G$.
So I was wondering if Chargaff's rule is really applicable?


texts:
Changes in WHICH of the following factors will result in a change of an ecosystem's structure and composition?

  A: nutrient availability
  B: temperature
  C: number of trees
  D: light intensity

I got this question from an online "fun" quiz.

I understand that nutrient availability would affect the carrying capacity of an ecosystem. Temperature, if there was a big shift, could cause a change because some organisms would thrive and others would not. Light intensity affects the autotroph population.

But why would the number of trees not change it? I would think that if the number of trees changes, then the structure of the ecosystem would also have changed.


texts: When free nuclear divisions occur(for instance in endosperm formation in coconut etc)....there are many nuclei undergoing kartokinesis at a given point of time...so that means each karyokinesis will naturally have to involve spindle fibre formation for the chromosomes to be pulled apart in anaphase....so when there are no cell walls or barriers and so many sets of spindle fibres...how is it that the spindle fibre of say dividing nucleus 1 doesn't go and attack to the chromosome of another dividing nucleus....shouldn't there be utter chaos out there as every spindle fibre can attach to any chromosome of any diving nucleus.....I hope you have u der stood my question


texts: In the life-cycle of the HIV virus, how does the created DNA enter the nuclear membrane?

texts:
I am in a high school biology class, so I cannot truly attest to how accurate the information I am given is, but as far as I know only RNA and very small molecules can enter the nuclear membrane through the pores on it (thus excluding DNA). Furthermore, I am fairly sure that the reverse-transcriptase used in the process of reverse transcription of the viral RNA must be used outside of the nuclear membrane, in the cytosol. My question is: How does the viral RNA, after it is reverse transcripted, enter the nuclear membrane?

My teacher and I have come to the conclusion that it probably creates the provirus sometime during mitosis, as the nuclear membrane dissolves, but this is more of an educated guess.

Thanks in advance!


texts: Why do sperm have centrioles and do female eggs cells even have centrioles?

texts: I was just wondering why it is that sperm have centrioles underneath the acrosome, but that also prompted a thought as to whether eggs have them too?


texts: What are the reasons which make intron detection uncertain?

texts:
Intron/exon sequence detection seems to involve statistical prediction which can at best deliver a guess (until experimentally confirmed) as to where the splice site is.

What are the reasons why there are no deterministic (rather than consensus) sequences which signal the location splice sites?

Trying to answer this myself, I guess the obvious one I can see is chromatin structure, which interacts with how RNA polymerase reads the DNA strand.  If this is the case however, isn't the current way of describing DNA as a sequence of AGCT base pairs fundamentally flawed?  If chromatin structure is actually part of the functional description of DNA, then are there any efforts being made to describe this?


texts: What histological stain can I use for beta-keratin?

texts:
I'm trying to find a histochemical stain for beta-keratin, the type found in Reptilia which is organized in beta-sheets. It's different than alpha-keratin which is found in mammalian skin, hair, nails, etc., and is formed of alpha-helices.

Simple searches have produced results specific to mammals and alpha-keratin. Are there any good stains for beta-keratin?


texts: Homology ratio comparison between different species

texts:
I found the following homology ratio:

protein coding genes of the organism with an homolog in mouse / all protein coding genes in the organism

I have done this for all protein coding genes between several organisms and mouse using a phylogenetic-based approach. I have noticed that the ratio found between an organism and mouse is greater than the ratio between another organism and mouse! On the other hand the second is evolutionary closer to mouse than the first.So:

1.Is such an approach trying to quantify homology? Which i know is not correct as homology is qualitive measure.

2.Can we compare the ratio of homology between the above 2 couples od species or such a comparison is biased?

3.Shouldn't the ratio of homology be proportional to the evolutionary distance of the organisms (according to conservation)?

As you can understand, in the way i calculate the above ratio, i don't take into account the one-to-many or many-to many relationships! I just take into account the genes that have at least one homolog in mouse..is that the bias of my calculation?


texts:
What is the largest (by large I mean most general) clade of organisms that has gone extinct?

domain > kingdom > phylum > class > order > family > genus > species

So, for example, an extinct kingdom would be larger than an extinct class.


texts: Can spike protein induced cell fusion be triggered by the mRNA vaccine?

texts:
The mRNA-based vaccines cannot lead to COVID-19 or its symptoms since they only lead to the production of the spike protein in the cell.
However, the spike protein itself can lead to cell fusion:
Quantitative assays reveal cell fusion at minimal levels of SARS-CoV-2 spike protein and fusion from without
Is this a potential risk of the mRNA vaccine ?
I could imagine, that the spike protein needs to be bound to the virus to induce this effect ?
I could not find any literature where the effect of the unbound spike protein is tested.


texts: Is it possible to make humans extinct artificially?

texts:
Verging on the realm of science fiction, my question is that is there any theoretically possible way, biologically/chemically, with which the entire human race can be killed without affecting the rest of the biosphere at all? I am only curious about theoretically possible no matter how unlikely. If we encounter a sufficiently advanced alien civilization bent on our destruction, would it be possible for them to make sure all humans die without harming any other living organism on our planet?

Is there anything biological/chemical which makes us unique or different than other lifeforms on Earth? Something which can be used against us? Or are we just so similar with a bunch of other species that we cannot be wiped out without other lifeforms getting harmed or our destruction cannot be ensured? Is it possible to artificially make humans extinct?

Thanks you.


texts: Predict if a given protein is recognized by antibodies

texts:
Assume that i have a 3d-protein structure in a PDB file on a computer. Is there any bioinformatic method to predict if that protein is recognized by all known antibodies of human and cause an immune response or not?
If the answer is yes, how accurate of these method?


texts:
Found two larva/eggs in a suitcase. The egg/larva were around same size or maybe little bigger than a grain of rice. When I put them on counter top to better examine, one hatched and a SINGLE insect popped out! It was fast moving when hatched and kept cleaning its legs. It was maybe the size of a grain of rice. I personally was thinking cockroach but it was a single insect from egg/larva!?!? Is it a bed bug or something else??? (We reside in Alabama.)
https://share.icloud.com/photos/0mQiO0JfeRwR3z7duvPSthrZw


texts: What role does a protein's size have on protein-protein interactions?

texts:
Protein-protein interactions are when two or more proteins bind together, possibly for some important biological function.  Recently, I'm starting to look more into proteins, and in particular, networks related to proteins, such as protein-protein interaction networks.  I found myself thinking about the following question:

  Question:  Does the relative size of two proteins significantly affect how likely they are to interact?  Does it affect how they interact?

It would be plausible for me to download a protein-protein interaction network, and calculate their relative size from the proteins' PDB files.  However, I predict that the results from such a computation would not offer much insight into why (or why not) the protein sizes affect binding.


texts: What is this strange mantis-like coral reef dwelling creature?

texts:
On the first episode of BBC's Blue Planet II they visited a coral reef and showed some odd reef-dwelling creatures as part of their establishing shots, but did not name the creatures.

In particular creature that resembles a mantis:

I tried a Google reverse image search and it very 'helpfully' identified it as "Documentary film". So close, yet so far.


texts: How Common are Paraneoplastic Syndromes in Cancer Patients?

texts: I recall reading around one in four cancer patients will suffer a paraneoplastic syndrome during the course of their illness but I can't find where I read this and I can't find any reliable sources to back this up.


texts: What phase of Action Potential (AP) exactly defines the Relative Refractory Period?

texts:
I am posting below, word for word, two statements made on Relative Refractory period - the first from the text: Human Physiology for Medical Students by Magdi Sabry, and the second from a web page with the URL:
https://content.byui.edu/file/a236934c-3c60-4fe9-90aa-d343b3e3a640/1/module5/readings/refractory_periods.html.
In addition, I've attached a photo from Google which appears to be in support of the second statement.
But which of these is correct?

"Relative refractory period (RRP)...corresponds to the remaining part of the descending limb of the AP till the start of after-depolarization (i.e. during the later 2/3 of RP)"

2."...there are two types of refractory periods; the absolute refractory period, which corresponds to depolarization and repolarization, and the relative refractory period, which corresponds to hyperpolarization. "


texts: Why do some viruses cease being a problem even though no vaccine or cure is found?

texts: No vaccine or cure has been found for SARS-CoV or MERS-CoV yet the world is not too concerned about them. How can it be? Did all people who had those viruses die or do viruses just randomly decide to stop being infectious at some point?


texts: Storing Taqman plates with polymerase in fridge before running

texts:
I'm going to be running some Taqman assays on cDNA generated from RNA collected from various samples, and will end up running a bunch of plates (right now the setup is 1/2 a plate per sample, including controls etc.). Since our thermocycler can only handle one 96-well plate at a time, it has been suggested that I make up the mixes all together, aliquot them into the plates, then store the plates at 4°C (well wrapped in plastic or Parafilm) until ready to run. I would imagine that the plates would be in the fridge for just one day, at max overnight.

My question is about the polymerase - can I add it ahead of time, and just take the plate out of the fridge and pop it in the thermocycler, or should I add it just before use? I've been kind of out of the DNA/RNA field for over 10 years, and I seem to remember from before that polymerases could have residual activity even at 4°C. Is this still the case, or have they improved to only be active at 60+°C or whatever your temperature is?

Alternatively, is there another ingredient I should leave out until just before amplification? cDNA? Probes? Something else? Also, does the storage time make sense? Is overnight okay, or should I run them all the same day? Is over the weekend okay? I don't want this question to extend into a too-broad "How do I do qPCR?" question, but any tips you have would be very helpful. As far as I'm aware, all the reagents are from Life Technologies/Applied Biosystems.

The reason I ask is because it seems to me that it would be much more accurate and reproducible to prepare the master mix with polymerase already included, instead of adding 1 μL of polymerase to each well just before running the assay.


texts: What is the pH of the mitochondrial intermembrane space?

texts: The proton gradient is stored between the mitochondrial double membrane. More protons mean more hydronium ions and lower pH, but how much exactly?


texts: What is the meaning of dots and dashes in clustalw?


texts: I know only that it is not a bird and an insect. I am really interested in from what it is.


texts: How are cell death like apoptosis and entropy related?

texts:
In Perspectives on Statistical Thermodynamics, Yoshitsugu Oono, it is written that

  Do not conclude, however, that since the second law is invincible,
  information thermodynamics is unimportant. It is possible for a system
  we are interested in to perform something that ordinary thermodynamics
  does not allow, and to pay the price somewhere else. For example, it
  may be possible to go beyond the limit of thermodynamics for the time
  being by shifting the average value of fluctuations, although the
  price must be paid (dearly) later. There must be such cases in
  molecular machines. It is argued that cell senescence is due to the
  accumulation of defects and wastes, but cell death could have a more
  active implication of carrying away the debt caused by utilizing
  information. Thus, entropic apoptosis and entropic altruism are
  conceivable.

but I don't understand the following two points.

Why is cell death associated with "debt caused by utilizing information"? Do cells die for increasing entropy to compensate the entropy decrease which caused by their using information (but what kind of information)?
Why can we conclude "Thus, entropic apoptosis and entropic altruism are conceivable."? Does this mean, to let other cells decrease the entropy by consuming information, some cells kill themselves to increase entropy?


texts: If proteins have an overall charge, how do membrane proteins traverse through the hydrophobic region of the plasma membrane?

texts:
These two concepts seem almost contradictory, proteins have a net negative charge due to the amino acids in them each having a small negative charge, yet membrane proteins are able to exist traversing the plasma membrane, which is impermeable to charged molecules (hence the need for membrane proteins).

How do these two statements remain true simultaneously?


texts: Asexual Reproduction Of sponges through endogenous or exogenous budding?

texts:
I was studying asexual reproduction in sponges and came across two website

Wikipedia of Gemmule and there is a line....

Only Endogenous Types of Buds develop into New Sponges.

Then as I was reading this Website Sponges there is a Section 9.1. iii) Budding, in which, there is Two Parts i.e (a) Exogenous Budding and (b) Endogenous Budding
So now, I am a bit confused..... if only Endogenous Bud can give rise to New Sponges then why there is a section of exogenous budding i.e reproducing through exogenous buds,in the reproduction section of sponges, in this website sponges ? ISN'T that Contradiction?


texts: How do APCs find their specific T-cells in the lymph nodes?

texts:
My understanding is that when an APC (more specifically a dendritic cell) encounters an antigen in the periphery, it ingests it and presents it on its surface. It then migrates to lymph nodes to activate the T-cell that has the specific receptor for this antigen.
Now, I know that T-cells circulate throughout the body, but given the amount of the cells in a lymph node, and the fact that only a few T-cells are specific for a given antigen, it seems to me highly improbable for the APC to meet the specific T-cell.
Is it really that the APCs randomly check every T-cell there? If so, do we know how long would that take? Or is there a way to quickly locate the specific T-cell?


texts: Why have certain plants evolved to contain psychoactive compounds?

texts: Plants such as marijuana (Cannabis) and kratom (Mitragena speciosa) contain compounds that affect the human brain. Why have these plants evolved to incorporate substances like THC and mitragynine into their leaves/flowers?


texts: Most sensitive hearing human ever measured?

texts:
The Fletcher Munsen curve shows the lowest spl that humana can hear is -6db around 4 KHz.I assume this curve is average obtained from measuring many people.

My question is,what is the most extreme hearing in terms of threshold spl ever measured? What person holds the record for most sensitive hearing?


texts: Could hydrogen replace oxygen in cellular respiration?

texts: I was wondering what oxygen actually does in the body. I have seen a few answers to other questions that involve the electron chain and I am really not sure what that is. So I was wondering what oxygen does and could hydrogen do the same thing as a substitute?


texts: How did life survive in the Snowball Earth theory?

texts: There is this theory that says that the whole Earth was once covered with snow and ice. How was it possible for life to survive this extreme state?


texts:
Why does antimalarial drugs causes hemolysis in g6pd deficiency patients?
I know that g6pd protects the cell from oxidative stress by maintaining glutathione in reduced state but how does the antimalarial drugs cause the deficiency of gsh? I came across this(https://malariaworld.org/blog/hemolytic-anemia-and-antimalarials) site and it says:

  The antimalarial activity of quinine and compounds vicine and convicine present in broad beans eventually follow the same path. In the gastrointestinal tract they are hydrolyzed to form unstable pyrimidine aglycones. They reduce red blood cell GSH and generate hydrogen peroxides and free radical species.

I highly doubt the last line, how does gsh produced not prevent the cell from hemolysis?


texts: How exactly can a drug affecting squalene epoxidase affect the methylation cycle, necessitating the use of 5-MTHF?

texts:
I found a case report in which the authors say that Terbinafine might have possibly affected the methylation cycle in a patient, necessitating the prescription of 5-methylfolate to correct the imbalance. I tried googling to find some description that would include the interaction of ergosterol synthesis and methylation cycle, and found nothing.

Maybe I was not googling the right words.

I can't seem to find how exactly we can affect the methylation cycle by affecting squalene epoxidase (the target of terbinafine, the drug used by the patient in the case report).

The article quoted is titled Antifolates and MTHFR (Trachtman and Pagano, 2015)


texts: How to increase contrast with only a top entry specimen holder

texts:
My question is: If my microscope had a top entry specimen holder, instead of a side entry holder, what additional option(s) should I have to increase the contrast with the same constraint that I only have a single objective aperture? Why would this option work?

Any ideas are welcome. Thanks in advance!


texts: We have all heard the typical “Put a jacket on youre going to catch a cold.” Usually stated by an older person typically a grandmother. Excuse the stereotype. Is there any evidence that colder weather makes one more prone to catching the flu or cold or is this simply a myth and misconception.


texts:
Will a bone marrow transplant change one's blood type?

Or is the donor blood type matched with the person before transplant?


texts:
I am inquisitive to know about how a person contracts AIDS.
Among the common masses it's still the belief that having sex with multiple partners causes the disease but that is not the case when read online that it can come only from persons carrying the virus.

So, if a person (male or female) is carrying the virus (HIV positive) does it mean that he/she is suffering from the disease or the person may be carrying the HIV disease and still be free from AIDS. If so how did this chain reaction of spreading the virus start?

Also is it true that immune systems of some rare people in this world can fight with this disease.


texts: I have simple question, do cis-eQTLs use the SNPs that are within 1 Mb from the gene's TSS on the same chromosome ?


texts:
Anybody knows which species (or genus, family...) of ant/wasp is that?

It's from Brazilian Amazon (Upper Negro River, Amazonas state). About 2-3 cm long (about one inch), maybe. It was walking on the sandy road around noon. Don't know the month of the year.


texts: Why my base-quality in alignment is not perfect?

texts:
I have a fasta file with some DNA sequences. I would like to simulate next-generation sequencing reads from it. I'm doing it without any base error and mutation error.

wgsim -e 0 -r 0 sequence.fa seq_0_1.fq seq_0_2.fq

To my knowledge, this is a perfect simulation. Next, I give the paired alignments to bwa for alignment.

bwa mem -M sequence.fa seq_0_1.fq seq_0_2.fq > P0.sam

Now, I check the ASCII of base quality (column 11 in the SAM format, the specification is here).

head -n 3 P0.sam | cut -f11

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

According to this page, the ASCII (in order of quality) is:

!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

Question: My experiment is supposed to be perfect, so my base-quality metrics are expected to appear near the right-end of the list (like x,y,z). However, my metric I is no-where near the top of the list. In particular, I'm unable to achieve anything from J to ~. Why?


texts: Cortical projections from layers 2/3 back to 4?

texts:
As all excititory neurons in layer 4 are stellate - they have no apical dendrites that could project to layers 2/3. However, I have seen some diagrams showing axonal projections from layers 2/3 back to 4, but then I see other diagrams that don't show it.

Is there enough evidence to show axon projections from 2/3 to 4? If so why do so many diagrams leave them out?


texts: Do phagocytes need antibodies to be able to engulf pathogens (to function)?

texts:
I recently saw a question about monoclonal antibodies, that are specific to a certain virus, being split (into their constant and variable regions via an enzyme), and the question asked whether some statements were false or true.
One of the statements said that the virus could be engulfed by phagocytes if any were present. The statement turned out to be false and I'm not completely sure why. Is it because phagocytes need fully intact antibodies to function so that they can attach to them via receptors specific to the constant region of the antibodies consequently becoming attached to the virus and so being able to engulf it?
I thought that phagocytes could work on their own and that antibodies just made their job easier. Is that assumption correct?


texts: What are the limitations of commercial-grade DNA genotyping compared to full sequencing?

texts:
I've heard about services like 23andme, which offer genetic testing to the general public. As a person who knows very little about genetics, I'm interested in the subject and would like to know what the modern "commercial grade" genotyping really does.  What are the limitations of commercial-grade "genotyping"?  From what I've been reading, they test DNA against ~100 different markers, but do not really sequence it.

If I understand correctly, if DNA is sequenced, genetic markers and genes can be identified in it, including the newly discovered ones. However, (if I understand correctly) if DNA is genotyped, the genotyping is a one shot operation which states if some genetics markers are present in the DNA. To test against newly discovered markers, it would have to be genotyped again, right?

Thank you for any clarifications!


texts: Whence fecal E. coli (et al.) if swallowing it is dangerous?

texts:
I don't know much about medicine, and I know even less about microbiology, but I understand that there are organisms in the lower gastrointestinal tract (and in feces) of a human, like Escherichia coli, that can cause dangerous disease if swallowed (or injected intravenously) by a human. So how did they get to the lower gastrointestinal tract in the first place? I assume either (or some combination of)

its prevalence in feces is less than I'm led to believe, so my question as to how it got there doesn't arise;
the percentage among cases of swallowed E. coli of those that lead to disease is low; or
E. coli-caused disease is more common than I'm lead to believe.

Does anyone know which of these is true? Or is it something else? (Perhaps they enter the gastrointestinal tract from below and not via swallowing?)


texts: What is the formal terminology for two species that are "close" to each other in a phylogenetic tree?

texts: Take for example the human and the chimpanzee, they are "closely related" species since they are "close" to each other in a phylogenetic tree. However, this terminology seems pretty informal, what would be the formal way to specify that two or more species are "closely related"?


texts: How common is it for environmentally occurring bacillus strain to contain some sort of plasmid?

texts:
I am designing a method for testing whether two new bacillus isolates, that are ionic silver resistant, store the silver resistance mechanism on a plasmid or on the chromosome of the bacteria.

In my method, after I do a plasmid extraction on the bacteria, I want to use nanodrop to see if plasmids are even present in the bacteria (if no plasmids are found, then the silver resistance mechanism must be stored chromosomally). After this, I want to use heat shock or electroporation to place the plasmid in a silver sensitive bacteria, and see if the newly transformed bacteria is ionic silver resistant (this would suggest the resistance mechanism is stored on the plasmid)

I have been looking at how other people have tested for this, and I have found that the nanodrop part is not done. I thought the nanodrop would be a good control to make sure the plasmid extraction went well, and if plasmid DNA was not found, it would save me from doing the rest of the experiment.

One reason why I thought they didn't do nanodrop was that perhaps most environmentally occurring bacillus contain plasmids, and thus nanodrop would be unnecessary step.

So my question becomes how common is it for environmentally occurring bacillus strain to contain some sort of plasmid? Also, if anybody has any suggestions for improvment of my method, please let me know.


texts: Why do cows (and other hooved animals) need a hierarchy?

texts:
Clearly numerous animals have a hierarchy - hereditary one.  For example, I understand zebras have a pecking order, and must map this hierarchy from highest to first in line and lowest to last in line when traveling, and they can be brutalized for breaking this hierarchy.  (Interestingly, they allow looser rules for their young.)  (Reference.)

Cows apparently spend inordinate amounts of time with certain other animals, and avoid others still. (Reference.)

My question is: why do animals need the hierarchies and alliances?  Because human adults tend to make friends with people based on the kind of people they are.

I would imagine that they may have signals that indicate competing survival strategies (for example, a man with thick, tattoo covered arms vs a man in a tie) and that these likenesses try to propagate at the expense of others by forming alliances using organisms that possess these attributes (very vaguely akin to "the selfish gene.")

Or does it have something to do with advertised fitness?  I just have to wonder how grazing animals manage to compete over food.  Does it control access to reproduction?


texts: Why a huge number of  trees/plants have cylindrical stems? I have been told that this question's answer lies in Physics but I don't know where to find. Can any one help?


texts: Would blue light be effective to help average people when sunsets come much earlier in the day?

texts:
I know people with SAD (Seasonal Affective Disorder) benefit from blue light in the winter as night-time comes much earlier (in the UK, sunset is around 4pm in December, compared to 9pm in June).

However, during winter (say the UK), would the average person also benefit from more blue light in the late afternoon/early-evening than standard light bulbs currently supply?


texts: Whether de novo mutation can be inherited or not?

texts:
Think about the following scenario: A child is diagnosed as having long QT syndrome, an autosomal dominant disease. However, neither of his parents is affected. This may be due to a new mutation in the embryo, which would explain the son having the disease with normal parents. Next, this de novo mutation could be inherited to off-spring of the child? or not?

And there are additional questions. Why do so many genetic tests performed by blood samples represent all germline mutations? Except for cell free DNA, blood cells are not germline cells. Therefore, the mutation found in the blood sample test may be a huge somatic mutation (except blood cancer). For example, for mutations that occurred early in embryo development, many cells may have been affected, and I think this might be in the form of somatic mosaicism. Doesn't it mean that it's a germline mutation if it's found at 50% or 100%?

I asked you a little more, is there only a family test (segregation test) that checks to see if it's a germline mutation?

Thank you so much in advance.
Please answer these long question, because no one answer me about this question.
If you answer me, I 'll always love you somewhere in the earth.

Thank you very much!! And I love you forever :)

And you say, in other words, de novo mutations can occur in postzygotic embryos or by germline mutations in parents.

Then I want to go further and conclude. In this case, an autosomal dominant disorder was detected as a heterozygote on a blood test. If it occurs in the embryo after conjugation, two possibilities are conceivable.

It could happens a heterozygous allele in the whole cell of a postzygotic embryo, Or can occur in one of the cells as a homozygous mutation when there are only two cells in the early embryo. In the latter case, autosomal dominant mutation would be lethal, so the child is likely not lived.

So in conclusion, if I thought that the whole cell of the child had the heterozygous mutation of the long QT syndrome, it was probably the result of the parent's germline mutation.

Am I thinkin right?


texts: If someone was urinating, and they were to hypothetically suddenly "fall dead" (the brain is unconscious and all muscles / organs are unfunctional), would they continue urinating or would it stop?


texts:
I know genes can be translocated between chromosomes but can nucleotide sequences be moved around within an individual gene?

Could the following gene:
MEN SAW OLD HEN

Become:
MSA WOL DHE NEN

By moving the EN at the beginning to the end?


texts: How to watch a Zebrafish embryo in detail?

texts: How much microscope zoom would I need to watch the development of a Zebrafish embryo in certain detail? Thanks guys!


texts: What's so special about Chassaignac tubercle?

texts:
1-How does massaging of carotid artery at chassaignac tubercle( anterior tubercle of transverse process of C6 vertebra ) can relieve the symptoms of Supraventricular Tachycardia?

My attempt: I think by massaging carotid artery we are somehow stimulating the satellate ganglion present at level of c7. Or, I think, by massaging the carotid artery we are increasing BP, thereby affecting the baroreceptors and somehow this relieves the symptoms of supraventricular tachycardia.

2-Why can't the same massage be done at level of other cervical vertebrae?


texts: How does acetylcholine (aCh) cause erection?

texts:
I have read this article on physiology of erection :

  Activation of cholinergic receptors on the endothelial cell by acetylcholine or stretching of the endothelial cells as a result of increased blood flow may elicit underlying smooth muscle relaxation through the release of NO.

I know erection is caused by parasympathetic outflow; but how come the cholinergic receptors on the endothelial cells are activated by aCh because there are no parasympathetic neuronal endings on endothelium, as from what I've learned and there could not be aCh freely released in penile arteries because butrylcholinesterase in blood would inactivate the aCh?

I understand that the corpora cavernosa are relaxed to help sinusoids accumulate blood and corpora spongiosum are contracted to prevent venous outflow of the blood to maintain the erection.


texts: Is a bone marrow transplant limited by sex?

texts: Can a female patient get transplanted with bone marrow of a male donor and vice versa?


texts: How did parasitoid wasps evolve their life cycle?

texts: I know there are a variety of wasps with various strategies for acquiring and controlling hosts. Do these form a rough picture of how these life cycles could have developed in the first place? What is the most recent speculation?


texts:
Occasionally, after someone's been, there is an awful acrid smell lying about long after them. What causes this? The food that they've eaten? Urea less dilute due to dehydration?

If it helps I've noticed it only with older males.


texts: Are Italians genetically separated from other Europeans?

texts:
I was reading this Wikipedia article about the genetic history of Italy, and I found it interesting.

There are however a few things that puzzle me, because they seem to contradict each other. For example it states that because of the Alps forming a natural barrier Italy is, along with Finland, a genetic island in Europe. Does this mean Italians and Finns are genetically separated from all other Europeans, and to what extent? Later in the same article it says that "In Italy as elsewhere in Europe the most common haplogroup is haplogroup H", which would seem to contradict the genetic island theory. After all, Italy has been colonized by countless populations throughout its history, which might suggest the Alps didn't really stop the gene flow from neighboring countries (not to mention that other European countries are equally separated by mountains, like Spain).

I have no background in genetics whatsoever, so excuse my ignorance, I'm just trying to understand an article that seems very confusing and throws lots of different information together.

EDIT: Thanks for the quick reply! I've found another link (which seems to be more reliable than Wikipedia's unverified claim), though it still sounds like a weird theory to me.


texts: What is the difference between local and global sequence alignments?

texts:
There are a bunch of different alignment tools out there, and I don't want to get bogged down in the maths behind them as this not only between software but varies from software version to version.

There are two main divides in the programs; some use local alignments and others use global alignments. My question is threefold:

What are the fundamental differences between the two?
What are the advantages and disadvantages of each?
When should one use either a global or local sequence alignment?


texts:
is it possible at least theoretically to change the DNA of an organism ?

so we take for example an organism with multiple cells then we change its DNA without killing this organism

to correct genetic defects or to improve it


texts: How would infection of mosquitos with sterilizing bacteria have any effect?

texts:
According to this article from the New York Post, the US just approved the mass release of male mosquitos infected with a bacteria that sterilizes them. The idea, according to the article and some inference, is that they'll mate with female mosquitos and impregnate them with non-viable eggs, causing a missing generation of mosquitos. Brilliant, right?

Well, no. Male mosquitos, from what I can gather, typically live less than a week in their adult phase, mating perhaps once while females will live for a few weeks mating, feeding, laying eggs and repeating until they die. Even if males and females both only manage to mate once, for every female you want to not produce viable young, you'd need to release one infected male. With a very conservative estimate of 10 trillion mosquitos in the United States, one generation per year, and current separation of male from female mosquitos in the lab by hand according to the article, you'd need to manually infect 10 trillion male mosquitos per year, for at least a few years, to make a serious dent in the mosquito population.

How does anyone think this is a practical idea?


texts: I know, or at least I think I do, that the contents of the stomach are called chyme and that it is acidic.  What are the contents of the small bowel called and is it acidic?


texts:
I'm not strong in biology, so bear with me on this:

I've been reading that as we age, our DNA is damaged by internal (e.g. errors during replication) and external (e.g. sun damage or radiation) factors.

If you take, say, an 80 year old, can you find DNA in their body that's the same as when they were a newborn? What kind of cells would have undamaged DNA?
Is DNA damage distributed evenly across the body or will some parts have more damage than others?
Is there any published data on how much DNA damage an average person accumulates over their lifetime? I'm not sure how this can be quantified, but I'm wondering if there has been any study on gauging damage.


texts: Smoking, cancer, correlation between quitting smoking and increased immediate risk

texts:
There is "proof" out there today that suggests smoking is directly linked to cancer. I cannot argue against that, for the evidence in favor appears strong, and the evidence against is lacking. I'll happily sit here and agree that smoking increases the risk of cancer. This question, however, is not about how smoking increases the risk of cancer, rather how stopping smoking might increase the risk of cancer.

Consider what I know so far:

Cancer is caused by mutant cell growth.
Mutant cell growth is believed to be caused by chemicals in the smoke
Smoking itself stunts growth, thus slowing the cell growth rate

If the growth stunt is severe enough that it will reduce the cell growth rate by 20%, one might assume this would take some weeks (let's say 8 weeks, sounds reasonable to me, though I lack knowledge of the subject) to recover. This will likely be some scale and will gradually decrease to somewhere near 0.

Further to this, the risk of cancer is not directly related to the lung, but it is believed to be caused by chemicals entering through the lung into the blood, and travelling around the body, causing cancer in various organs.

Consider that the cell growth is probably linked (in the lung, at least) to chemicals "surrounding" the existing cells, this explains why smokers run short of breath. This partially explains the growth stunt side of smoking. Perhaps this happens body-wide, I don't know.

Then consider what will happen when one stops smoking. The cell growth rate will begin to radically and unexpected increase as the growth stunt is suspended, meanwhile chemicals will still exist in the blood and organs which will be perverting cell growth causing mutant (cancerous) cells. At this point the body is unprepared and settled into its routine of slowly generating cells, but now it is generating them faster and is struggling to keep up. Energy is lacking in areas, and there is further cause of mutant cells to grow and even to be allowed.

Surely, given this reasoning, it might be understandable that stopping smoking increases the immediate risk of cancer, though reducing the long term risk?

Does anybody know, or can anybody find reasonable proof that any part of this argument is flawed? Is there any research to suggest that there is or is not an immediate increased risk? The one thing that people never mention in the side-effects of quitting is the risk of immediate body failure through a variety of means (I've known people to come with flu-like symptoms then find they have cancer weeks later). Is this really unexplored? Or is the nanny state trying to hide it from smokers to prevent them from damaging their health further?


texts: Did my wildlife camera take pictures of coyotes?

texts:
A wildlife camera took these photographs of these animals. These are the only pictures my camera collected of them. This picture was taken in the central interior of British Columbia, Canada. The distance from the camera to the subject is a few meters, and the height of the camera off the ground was probably about 50 cm.

I think they're too small to be wolves, and they don't appear to be any of the dogs I've seen in the area. My intuition strongly points to them being coyotes based on pictures, videos, and occassionally seeing them in the light of day. However, I'm hoping that someone can explain why my intuition is right, if it is right.

The small coniferous tree beside the road (left of center) is about 50 cm tall.


texts:
What is the window during which division into twins is possible (for instance can it still happen after implantation in the uterus)?
Is one twin the "original" and the other its clone?


texts:
I have a basic and probably silly question. I am isolating RNA with TRIzol. I have performed the basic steps and dissolved the pellet in 50 uL water. I ve measured the concentration and it was 3313 ng/uL (Around 165 ug total yield.). Now my next step is DNase treatment. It says 1 unit of enzyme for 1 ug of RNA in 10 ul reaction mix. I would like to dilute my RNA to 100 ug and use 100 units of enzyme in a 1000 uL reaction mix.

Is this logic true, and if it is how I am going to do the dilution?

Thanks!


texts: What is the inbreeding coefficient for the female offspring of a sib-mating in a haplodiploid system?

texts:
The inbreeding coefficient of a sibling mating for a diploid organism is 0.25 (each allele has a 25% of being identical by descent in the offspring).

In haplodiploid organisms, males result from unfertilized eggs, so they don't have fathers (they get half of mom's diploid genome, and that's it). Females have both a mom and a dad, and are diploid in the standard way (dads give their daughters their entire genome).

What is the inbreeding coefficient for the daughter of a sib mating?


texts: Can we safely use the terms DNA and Genome interchangeably or is there any (even slight) difference between the two?


texts: How to run agar gel electrophoresis at home

texts: I've looked at various sites explaining how you can easily make your own gel electrophoresis kit at home. But they always test various food dyes on these home made kits instead of actual DNA samples. Extracting DNA from plant matter can also be done easily at home, so why can't you just run this on the homemade kit?


texts: How do pet gecko lizards pose a health risk?

texts: Does having gecko lizards living in your house pose any health risk?


texts: B-cell and T-cell activation by parasites

texts: Parasitic infections lead to the production of parasite-specific IgE, but they also lead to the activation of nonspecific, polyclonal B-cells and T-cells. How do parasites trigger non-specific activation?


texts: Identify this insect with a big "face" pattern on its brown fuzzy wings

texts:
Hiking in low mountains in northern Taiwan in early May I noticed that something seemed to be looking at me from the ground, and it turned out to be the pattern on an insect's wings.

The wings are fuzzy like a moth or butterfly but they fold back.

There is also a striking face-like pattern on the wings, one "eye" with heavy upper eyelid on each and a "mouth" across both, and it has very long black (or blue?) and white densely-striped antennae or feelers which project straight forward, and it's legs were also black with several white bands. The length from head to wingtips (not counting antennae) was about 2 or 2.5 cm.

I also got the distinct impression that its orientation was not flat (parallel to the leaf's surface) but oriented with its rear high, so that something in front of it could see the "face". I don't have a photo from the side but based on judging things from what is and isn't in focus I think it's pretty clear.

Question: Is it possible to identify this insect with a big “face” pattern on its brown fuzzy wings? Is it also possible to know if the pattern has some underlying structural function within the wings, or is it only for appearance?


texts:
Let's suppose that I take a DrugA for ProblemA and then I got this ProblemB and started to take DrugB. Are there general rules I can look up to figure out whether I can take DrugA & DrugB simultaneously?

I mean drugs can cancel each other or vice versa increase effects of each other (in an extreme extend); or one of drugs has adverse effects that are bad for the other drug.


texts: Under what circumstances and why is terrific broth preferred to LB broth for E.coli growth?

texts:
Terrific Broth will result in a greater density of cells compared to LB but I have certainly seen it isn't as effective for the protein production of certain proteins compared to LB or defined media. I was curious what other limits and constraints exist with TB.

Migrated and derived from Quora http://www.quora.com/Under-what-circumstances-and-why-is-terrific-broth-preferred-to-LB-broth-for-E-coli-growth


texts: How scientists can be confident that human embryo tail is really a tail?

texts:
From Wikipedia:

  Human embryos have a tail that measures about one-sixth of the size of the embryo itself. As the embryo develops into a fetus, the tail is absorbed by the growing body.

How are we sure that it is a real tail and is not a superficial resemblance of something else?

I ask this because some creationist guy challenged me in this regard.


texts: Low migration rate in Papadopoulou et al. (2008)

texts:
In the paper "Speciation and DNA barcodes: testing the effects of dispersal on the formation of discrete sequence clusters" by Papadopoulou et al. (2008), is there an explanation as to why the authors simulated very low migration rates ($m$ between $10^{-8}-5\times 10^{-5}$)? The population size was 160,000, which produces $Nm$ between 0.0001-0.5. This is much less that a single migrant per generation.

Any insight would be most appreciated.


texts: What are the factors to consider when determining the sample size for a given study?

texts: Say I'm designing a retrospective study (where I'd collect data from various schools for the last 5 years) to see if consuming milk can contribute to childhood obesity.  How do I decide on how many schools to visit? If I remember my stats correctly, in general, the goal is to achieve 95% confidence in our results, right?  So how many schools would I have to collect data from so that I will have 95% confidence in the outcome of the study?


texts: Are sensory mechanoreceptors and mechanical nociceptors the same type of neurons or are they different?

texts:
I always supposed the neurons / receptors which transmitted touch and pain were the same, since they react to stimulus which are the same but with different intensity, and they just sent a stronger signal in the case of something that has to be interpreted as pain. Though recently I've read some articles that imply they aren't, even so they don't say it directly. Reading more information I found this,

A nociceptor ("pain receptor") is a sensory neuron that responds to
damaging or potentially damaging stimuli by sending “possible threat”
signals.
Types and functions
Mechanical nociceptors respond to excess pressure or
mechanical deformation.

Nociceptor
Then,

Are sensory receptors neurons?
Receptor cells are specialized neurons

Are sensory receptors neurons?
And finally,

Sensory receptors are primarily classified as chemoreceptors,
thermoreceptors, mechanoreceptors, or photoreceptors.
Mechanoreceptors detect mechanical forces.

Sensory receptors
This doesnt give me a definitive answer, but it tells me both "sensory mechanoreceptors" and "mechanical nocireceptors" are neurons which responds to pressure/ mechanical forces. Are they supposed to be the same types of neurons named differently by different authors, or are they different types of neurons?


texts: Gene silencing: relative or absolute number of methylated CpG sites?

texts: CpG content varies a lot across the human genome. What does determine a promoter to be silenced through DNA methylation: the fraction of CpG sites that are methylated or the total number of methylated CpG sites? Any reference?


texts: 3 primers to know if Homozygous, Heterozygous or WT

texts:
In this imaginary experiment, I am using T-DNA to make an insertional mutagenesis that will get randomly inserted into the DNA where it might get inserted within a gene, disrupting it.
In order to get homozygous individuals, If I working on plants, I could self-pollinate this particular plant that has had this gene disrupted making homozygous offspring.
In order to prove that, I can do a PCR using 3 primers.
My question is, why 3 primers? I would use 4 primers!
I have been researching it and trying to understand it for myself for a while, but I do not reach any positive conclusion. I think it should be pretty basic and I am missing something.
I think I need forward and reverse primers for the T-DNA, but what about the 3rd primer? If I only use these two primers, though, I will not be able to distinguish between the homozygous and heterozygous.
Thanks!


texts: Could you save a species if there were only two remaining?

texts:
Let's say an endangered species had only two left (male and female) and they produced 4 children (two male, and 2 female), and those produced? Wouldn't the incest slowly degraded their genes? (Assuming the pair of children created 4 children each, etc)

My main question is could you really save a species with only two?


texts: Can Anyone Identify This strange cockroach looking bug

texts:
I am looking for someone to identify this bug:
location india. It flew from my window in my room, killed it by spraying cockroach killer spray, it could fly like cockroach.


texts: Reference request: Lipid composition in bacterial, yeast and human membranes

texts:
I would like to know about the lipid composition of different kinds of cellular membranes. I remember going through such a table once in a paper, but I am unable to find it anymore. What I am looking for is a kind of tabular data which shows the percentage of phosphocholines, cholesterol, sphingolipids and other kinds of lipids organism-wise (and if possible tissue/organ/organelle wise wherever applicable).

So please share the papers/links/books etc where I may find this information. Thank you.


texts: Understanding Membrane / Resting Potential from the perspective of ions?

texts:
From wikipedia article RESTING potential: "there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemical potential is hugely greater than the effect of concentration so an undetectable change in concentration creates a great change on electric potential."

the effect of charge on electrochemical potential significantly larger then the effect of charge on concentration - is this a general statement or true in all cases?

And if charge is more significant then concentration in influencing electrochemical potential why does a small change in concentration greatly effect electropotential? Or does it mean electrochemical potential? Either way how does it make any sense, is it correct or nonsense and what is the exact meaning behind the message?

other questions I have:

1) What is the reason Na+ stays at its location right across the barrier on the extracellular side of the membrane? Diffusion? Electrochemical potential? Electric Charge.. if so because of Attraction or Repulsion?

2) If the answer is the electrochemical gradient/potential, because it is trying to move to a "less" positive potential.. if its located extracellularlly isn't that the "great unknown" where any molecules/cells/protein etc. are able to float by and possibly influence it? What happens if one of these has a "LESS" positive potential then the membrane that Na+ is currently attracted?

3) Why can't Na+ be used for the entire process to establish the same voltage interactions leading from resting to action potential (as long as thier was less concentration intracellularly... if it is about LESS positivity ..Or vice versa for K+?)?

I am preparing for ACSM certification exam, so any help is appreciated.


texts: Nonlinear (Quadratic) selection gradients formula

texts:
Under scenarios of stabilizing or disruptive selection, we can add a quadratic component to our model of phenotype and fitness like so.

Specifically, I am not clear on where the 1/2 comes from nor do I understand the derivation of gamma, which is equal to as follows:

x is the phenotype of interest, w(x) is the fitness of said phenotypic value. uBS is the mean phenotype before selection. Any help would be greatly appreciated.


texts: How much Oxygen can the Human body carry?

texts:
Basically - the title: How much Oxygen does a human body carry at a single point?

What have I tried: A friend of mine has done some calculations and came up with the following numbers. Neither of us are biologists or have higher degrees in biology. His calculation went something like:

Our body absorbs about 0.033g of Oxygen when we inhale (source).

That's about 0.00103 moles of oxygen.
Through ATP reaction that's about 0.00515 moles of ATP

We have 270 millions of hemoglobin per red blood cell, and roughly 25 trillions of blood cells in our body (wiki), and each Hemoglobin molecule "carries" up to 4 oxygen molecules.
Thus, in total, our body's hemoglobin can carry about (2.5 * 10^13) * (270 * 10^6) * 4 = 1.437 grams of oxygen

How far is the 1.437g number have?

Related (but not the same question) question I found here: How much energy we get from oxygen?.

Note: this is specifically about oxygen we use in our respiratory system - and not the oxygen in the water :]


texts:
The following case study has a student working with blood samples to
  identify their blood types (A, B, AB, and O). Consider the situation
  and answer the questions.

  A student is given eight red blood cell suspensions, which contain
  only red blood cells, and the matching serum from each sample. (Serum
  is blood plasma in which fibrinogen has been removed.)

  She is asked to identify each of the four different blood types
  present. To test these samples, the only materials she has at her
  disposal are a sample of type A red cell suspension and the serum from
  type A blood.

  Describe the step-by-step procedure that she must use to identify the
  four different blood types present. In each step, interpret what it
  means if the cells in the sample clump together, or if they do not
  clump together.

I am mostly confused on what exactly "she has at her disposal are a sample of type A red cell suspension and the serum from type A blood." means..? What is a A red cell suspension?

I already know that:

TYPE A: has anti-B antibodies

TYPE B: has anti-A antibodies

TYPE AB: has neither anti-A nor anti B antibodies

TYPE O: has both anti-A and anti-B antibodies.


texts: Bacteria surviving a β-lactam antibiotic

texts:
What changes can occur in the cell wall of a bacteria for it to survive a β-lactam antibiotic?

I think that because a bacteria possesses peptidoglycan in its cell wall, they are β-lactam sensitive, hence the only way it could survive a β-lactam treatment would be the presence of a resistance gene caused by a mutation.
I can't think of another way.

Any ideas?


texts: Are sulfates or nitrates common ions in biochemistry (specifically of the body)?

texts:
It's a rather broad question but something I'm curious about.

I know sulfates tend to be very soluble ions and so don't know nitrates.
I also know that phosphates are extremely common in biochemistry (e.g. ADP) but they're not very soluble unless they involve group 1 elements, same goes for carbonates.
I think Carbonates tend to be more common in crustacea, or chicken egg shells. I can't remember if it's found in the Krebb's cycle (don't think so, but maybe in other vitamins?).

Solubility isn't apart of this question, it was just one of the ways I was just trying to pursue an answer. I'm more of a chemist than a biologist...


texts: How does an electrical impulse spread in a muscle fiber spread from the motor end plate?

texts:
Does this impulse in skeletal muscle spread much in the same way it does in neurons, with an initial potential change that spreads to its immediate surroundings and is then re-amplified or is it the case that in muscle fibers, the initially produced end plate potential must be "enough" to depolarize the whole muscle fiber?

My issue is with this bit in a lecture about NMJs I took:

  Because the ACh-gated ion channels are localized to the end plate membrane, the End Plate Potential (EPP) is generated at and confined to the end plate region only and, therefore, the amplitude of EPP declines progressively with increasing distance from the end plate region.

I only found this site which talked about something similar, and there it talked about it in the context of a muscle fiber that's been blocked by a non-depolarizing neuromuscular blocker, i.e., no contraction occurs, it's just a measurement of how the EPP changes by itself, so perhaps the lecture was talking about something similar?

So, to put it simply, do electrical signals in skeletal muscles get re-amplified as they travel along the fiber, like they do with neuronal action potentials, or is the initial membrane potential sufficient and it just "spreads around"?


texts: Identification of proteins in this animation of a ribosome translating mRNA

texts:
This gif is from this page
After each aminoacyl-tRNA enters the ribosome, one blue thing comes and pushes the whole tRNAs whats that? I couldn't find it anywhere.(maybe some elongation factor?)
Also it seems that some thing is transporting the tRNA itself (maybe aminoacyl tRNA synthetase?)


texts: How hot can a beverage get without burning the tongue?

texts:
What is the maximum temperature that a beverage can be without burning the tongue?

I suspect there's a maximum temperature that the surface tissue of a tongue can withstand without being damaged (causing the burning feeling that lasts even after the heat goes away). So let's say I want to setup a device to keep my coffee to the right temperature to drink without damaging my mouth - I'm interested to know the highest possible temperature that will not damage the surface tissue of the tongue in a way that will result in lingering pain after the heat is gone.


texts: How to measure surface area of plated bacteria?

texts:
For my project, I'm growing Baker's yeast and probiotics in two liquid cultures before mixing them together and plating them.
I'm trying to measure the impact of the probiotics on the yeast.
How could I measure the amount of fungi on the plate, whether by cell counting or surface area?


texts: What ailments used to be completely fatal (or nearly so) but, now modern medicine has a treatment or cure?

texts: My brother was a Type 1 diabetic and back in high school I did a report on diabetes. One of the things that struck me was that before 1921, type 1 diabetes was basically 100% fatal. I was wondering what other common ailments have effectively nullified. Other examples are smallpox, polio, and the bubonic plague, but these are all infectious. I was wondering if there were other ailments that a child is born with or later develops that used to be highly fatal, that is now easily treatable?


texts:
This was taken in Ann Arbor, MI.  It looks a bit different from the wolf and grass spiders I'm used to seeing.  Anyone know  what this might be?

edit: Per request, I've uploaded a better picture.  Actually, it's the same picture, but I postprocessed the first image quite a bit to ease identification.  The second one is not post processed but (hopefully) clearer.

Processed image:

Unprocessed image:


texts: Steps to confirm if predicted miRNA is good or bad

texts:
I aligned all miRNAs available to the supercontigs of a particular genome with certain parameters (e value of 0.01 and a word match of atleast 7 as suggested in this paper). I have also isolated the pre-miRNAs (+100 nucleotides from either end of the match area). What would you suggest as ideal ab-initio methods to confirm that these miRNAs do exist in that particular genome? Some papers I found use mFOLD like this.

What would you suggest as best steps to confirm if a predicted miRNA/pre-miRNA is really present in the genome.


texts: What's the ratio of saturated to unsaturated fatty acids in human cell membrane?

texts:
It's well established that the fluidity of a cell is largely dependent upon the ratio of saturated to unsaturated fatty acids that exist within the membrane, but, what exactly are the values for this ratio?

Given that cells maintain a constant degree of fluidity (assuming constant environmental conditions), I would think this ratio could be properly defined.

I've tried looking through several molecular biology books and I Googled for about 30 minutes, but nothing..

Can anyone provide this ratio, or, explain why it's not obtainable?


texts: What do the the different arrowheads mean in a cell signalling diagram?

texts: What do the different arrowheads mean in the figure below? Are there arrows upstream or downstream signalling?


texts: It is known that there are animals that acquire toxins through their diet or through their surroundings. The examples I know of include butterflies stocking up on alkaloids/glycosides while in the caterpillar stage (monarchs snacking on milkweed come to mind), fish acquiring ciguatoxin or tetrodotoxin from marine bacteria, and arrow poison frogs and pitohuis acquiring batrachotoxin and other nasties from the insects they eat. Are there any other nice examples of animals like these?


texts: Can anyone identify the worm in this video clip?

texts: My wife came across this youtube clip of a spider and a worm. Can anyone identify at least the phylum?


texts:
I want to ask a question about xylem in the centre of the root.

I am reading a book about transport in plants, and it reads this regarding the root structure:

  Roots are subjected to vertical stresses - they have to be able to resist being pulled out of the soil.  A central core of strong xylem tissue gives ideal resistance to being uprooted and at the same time gives economy of space.

I'm confused about this passage.
How does the centre of the root being xylem tissue exactly prevent the resistance to pulling forces upwards out of the soil?


texts: Why are Chromosome Territories important?

texts:
Chromosomes occupy discrete regions of the nucleus, referred to as 'Chromosome Territories'. This spatial organization is emerging as a crucial aspect of gene regulation and genome stability in health and disease.

But how is this the case when:

Most eukaryotes seem to have Chromosome Territories, but yeast S.
cerevisiae is an exception to this.

So if some eukaryotes do, and some do not, what information do Chromosome Territories provide? Some literature uses the phrase 'non-random chromosome territory arrangements'. Thus, I am confused.
Chromosome territories are randomly arranged in some eukaryotes.
How are chromosome territories crucial for gene regulation and genome stability in health and disease in some  eukaryotes, but random in other eukaryotes?


texts: Why doesn't human consumption of plants cause infectious diseases the way consumption of animals can?

texts:
At first I want to clarify that I do know that there are naturally poisonous plants and plants that can hold radioactive stuff or toxic material from the environment.

What I mean by "diseases" (I guess there is a special term for that in English) is Bovine Spongiform Encephalopathy and similar serious issues caused by eating animals, by that you cannot develop when consuming plants.

As far as I know there are no diseases causes by eating fruit and vegetables (of course, except parasites if you don't wash it properly and an infected cow or bunny pooped on it ;D)

Is it because the parasites and diseases infecting plants are so specialised for their "body-type and genetics" that they cannot operate inside an animal body?

Could somebody explain that to me in more depth why by eating plants you cannot get a disease (except allergic reaction/intolerance or toxicities as mentioned earlier)?


texts: Synaptic connectivity in the newborn's brain

texts:
In my understanding, learning is related to the strengthening and weakening of synaptic connections. Very roughly said: Synaptic connections that are used often are strengthened, those that are used rarely are weakened. This is basically the Hebb rule.

Assumed that the Hebb rule holds at least partially (of course, there are other factors at work during learning), I wonder if in a newborn's brain the areas where learning will take place are equally weakly connected by synapses (so the pathways will be "built up") or are equally strongly (maximally) connected (so the pathways will be "carved out") or something inbetween. Or are there areas of both/all kinds?

(I assume that there is a maximal connection strength beyond which no further strengthening takes place.)


texts: Retrograde/anterorade transport; kinesin/dynein; COP1/COP2; Endoplasmic reticulum/Golgi

texts:
I am getting slightly confused with all of the terms above and was wondering if someone could see if I have got this right:

I think transport from the ER to Golgi is almost always from the plus end of a microtutbule to the minus end, and therefore is carrier by a dynein. I think this is signalled by a COP1 protein, which can attach to the dynein for transport. I think that this is retrograde trnsport as it is from the plus end to the minus end, however this I am really not sure about.
Conversely, I think that transport from the Golgi to the ER, being from the minus end to the plus end, is carrier by kinesis and therefore the COP2 protein which attaches to the kinesis carries these vesicles. I think this is an example of anterograde transport.

My confusion lies in the fact that

I am not sure whether retrograde and anterograde transport refer to movement from plus and to minus end of a microtubule or vice versa (respectively) or whether they refer to general motion of cargo into and out of the cell (respectively). For example, if a vesicle was being transported from the plasma membrane to the Golgi and then to the ER, the first part of this journey would be along the plus end to the minus end of the microtubule, carrier by dyneins; the second part of the journey from Golgi to ER would be from minus and to plus and and therefore carried by kinesis. Would this transport therefore initially be retrograde and then anterograde, or do these terms simply refer to the general direction of motion of cargo into/out of a cell and therefore this whole motion would be described as retrograde?

Secondly, if I remember correctly my lecturer said that one of the COP proteins takes proteins from the Golgi to the ER and the other takes froteins from the ER to the Golgi to the plasma membrane. This is confusing me because it would mean that the same COP protein would take a vesicle from plus end to minus end of a microtubule from ER to Golgi, and then from minus end to plus end from Golgi to the plasma membrane, which surely can't be right as the same protein should not be recognised by the two different motor proteins, right? However if it were the other case, that say COP 1 takes vesicles from ER to Golgi and COP 2 takes them from Golgi to ER OR from the Golgi to the plasma membrane, what would distinguish whether the cargo was taken to the plasma membrane or back to the endoplasmic reticulum?

Thank you in advance!


texts: Intro Bio question: dihybrid punnet square

texts: Today we had our exam. There was a punnet square for two genes. and when I multiplied , for example, Ry × rY I wrote the answer as RyrY. When I returned back home I realized that I may have made a mistake because the book used to write them as RrYy. So is my answer write or wrong? why? I also freaked out because there were 16 boxes in the punnet square so does that mean that I'll lose 16 points? I got everything else in the exam correctly. So I'm freaking out because I don't know if I'm getting a 100 or 86 which will throw all my work the entire semester. Please respond as soon as you can. I feel like I'm having a panic attack.


texts: What does the (-) in the molecule name mean?

texts:
I'm reading some text (purchase request) that has the following line in it.

  (-)-Norepinephrine

What does the minus sign mean in front that is in parenthesis? Is this some kind of standard way of describing charge of the molecule or something? Or is this someone's way of representing something else? Or does this mean nothing?


texts: Tool for translating chomosome, index numbers to sequence information

texts:
Is there a tool which allows me to transform information in the form (chromosome number, start index, end index) to sequence information? For example, something like (6, 43770819, 43770841) should yield GACCCCCTCCACCCCGCCTCCGG as this is the relevant bases on the 6th chromosome.

A command line executable is preferred, although a web-based service is also fine. Thanks a bunch in advance.


texts: Are there any barriers to telomere sequencing other than length?

texts:
In the comments to an answer on this question, it was noted that long read sequencing methods (e.g., from PacBio or Oxford Nanopore) have largely eliminated repeat-based assembly problems for bacteria. This paper on centromeres suggests that this is nearly the case for those sequences as well.
Telomeres, however, can be much longer, up to 50kb for humans. Read length is thus obviously still a barrier for telomere sequencing, even with the best current technologies.
My question, however, is this: are there any other barriers besides read length? Telomeres also have other modifications, such as their loop structure, and are famously subject to degradation. Do these or other issues also pose barriers to sequencing, or are they readily dealt with in normal protocols?


texts: Can anyone tell me what type of worm this is?

texts: I sure hope you can see this picture. Need to know what type of worm this is. Found one in July and one just now inching its way across my tiled floor. I live in Florida. It is one color all the way around, dark red.


texts:
I have read about cortical circuits in the context of connectomics (e.g. any example here) and computational neuroscience (e.g. any example here), but a simple Google/Wikipedia does search not show an exact definition.

What exactly is a cortical circuit?


texts: Why are there inverted repeats in response elements?

texts: The following picture shows an inverted repeat sequence in a response element. Response element sequences for glucocorticoids, estrogen, and thyroid hormone show that they all contain inverse repeats. Why do these inverted repeats exist in so many response sequences? In other words, what advantage do they pose to the function of the response element?


texts: How can hyperthyroidism induce osteoporosis?

texts:
It says in my physiology notes that hyperthyroidism can cause osteoporosis.

I've been trying to figure out how this could be possible for a little more than an hour now. Every article that I look at seem to agree with the fact, but I can't find the explanation as to why it is that way.

In MarieB, it says T3 and T4 favor bone growth. Calcitonine also favors bone formation.

How can.... too much of an hormone that favors bone growth, cause bone resorption?


texts:
In the recent Nature Chemistry paper I-motif DNA structures are formed in the nuclei of human cells (open access link in LATimes) figure 1a shows "Schematic of i-motif and G4 structures."

I'm not a biologist, nor a chemist, so please forgive if the answer to my  questions seems obvious. I've looked at Wikipedia's Structural Motif article but there's little there about nucleic acids.

The length of the unlinked strand seems shorter, is this just because it is a schematic, and in reality the two branches would have the same number of bases?
What does the presence of the dual left and right arrows in G4$\ce{<-->}$ iM in the figure mean in this case? Does it suggest that a single molecule can change configuration back and forth between two distinct structures, or something else?


texts: Inheriting Modified DNA after CRISPR editing

texts: If CRISPR is used to modify the DNA sequence to cure a disease - say MS in a woman - will the RNA guides also modify the sequence in her eggs so her children could be born without MS inherited from her.


texts: How to evolutionary explain menstrural cycles synchronization?

texts: Sorry, I can not indicate the source, but I read that menstrual cycles of women who live in the same house over time sync. Is it true? How does it work?


texts:
I'm an electronics engineering student and I am going to use a sensor that detects infra-red emitted by birds that invade rice paddies.

Do birds emit infra-red radiation?


texts: How can we tell which direction sound is coming from?

texts:
Pretty self descriptive, without being able to view the source of the noise how can we tell the difference between a sound in front of us and a sound behind us if pitch, volume and distance are all the same.

Also assume that it is not biased to one side more than the other, e.g its not to your left or right but directly in front or behind.

I'm interested in knowing if it is a part of the ear that makes this distinction, or a function of the brain.


texts:
Let's say we are talking about a complex being with many variations.
Let's take coat colour as an example and pretend we have a creature with codominant genes to do with coat colour (for example BR (B for black and R for red, assuming they're both dominant and visible).
We now breed said animal to a co dominant coat type of a different variation (for example, YW (Y for yellow and W for white, assuming again that they're both dominant).

Assuming all 4 dominant genes are as dominant as each other (so red isn't going to appear over yellow, for example)
What comes out of said breeding?


texts: How best to count bees entering and leaving a hive to measure hive activity?

texts:
This is my first question here, so I apologize for all mistakes I could have possibly made.

I'm a high school student in East-Central Europe and I need to complete some research for a biology contest (asking for advice is accepted, so I'm not cheating). My task is to analyze the influence of certain environmental factors (temperature etc., it's not that important for my question) on the activity of bees. The method is pretty simple: once a week I record the entrance to the bee hive (I do it on four hives), play it in slow-mo (It's impossible to count them properly without doing so) and simply count the number of bees entering or leaving.

Problem is, I don't know how long the observation should take. I play it in like X1/8, you need to play it twice (entering/leaving), so it takes a lot of time to gather one piece of information for a certain day. Till now I've been doing it for one minute - and there seems to be some kind of pattern to their activity analyzed that way. Yet, I'm not sure if it's actually eligible. I can't do the observation for hours - I still need to learn and have other duties.

So, what should I do? Could anyone give me some advice? Is one minute (several, like 6 times a day per hive) legitimate enough?

Thank you in advance.


texts:
I'm reading this fantastic article on estimating body time: Molecular-timetable methods for detection of body
time and rhythm disorders from single-time-point
genome-wide expression profiles and one of the things that is not very clear to me is how the researchers estimated which genes are expressed and which ones are not:

  Total RNA was prepared by using Trizol reagent (GIBCOBRL). cDNA
  synthesis and cRNA labeling reactions were performed as described (5).
  Affymetrix high- density oligonucleotide arrays (Murine Genome Array
  U74A, Version 1.0, measuring 9,977 independent transcripts) were
  hybridized, stained, and washed according to the Technical Manual
  (Affymetrix). Affymetrix software was used to deter- mine the average
  difference (AD) between perfectly matched probes and
  single-base-pair-mismatched probes. The AD of each probe was then
  scaled globally so that the total AD of each microarray was equal. The
  resulting AD values reflect the abundance of a given mRNA relative to
  the total RNA popu- lation and were used in all subsequent analyses

I'm not sure if I'm reading this correctly - did the researchers look at all RNA available in the cells and calculated the levels of messenger RNA produced by expressed genes? if not, how can the level of expression of a gene be estimated?


texts: How does sleep prevent our eyes from drying out?

texts:
If we don't sleep for about 16 hours, our eyes start to get dry, and no amount of eye drops helps. You use eye drops and then you're dry 10 minutes later.
However, after you've slept for 8 hours, your eyes can go another 16 or so hours without drying out.
What specifically happens to our eyes during sleep that prevents them from drying out in the next 16 hours after sleep?
Are there any research papers explaining the mechanics of all this?
The reason I am asking about this is in order to understand whether there are any connections between nasal and eye moisturization.
There's a condition called empty nose syndrome, in which people with reduced nasal turbinates suffer from a range of symptoms and a lot of them have to do with their nose getting dry.
Here's a CT scan of a person suffering from empty nose syndrome in one nostril. As you can see, one of their turbinates has been reduced, and the other one looks normal.

There's something called "the nasal cycle", it's a phenomenon where turbinates swell up on one side at a time in order to "rest", according to wikipedia. Here's a picture illustrating the nasal cycle:

As you can see from the picture, one nostril of this person is mostly closed, due to cavernous tissue being swollen. It is not a disease, it is actually how our nose normally works.
Of course, if you have reduced nasal turbinates, like in the first picture, it is impossible to properly close the nasal airway and expect it to "rest", so that it can start producing moisture again.
Does that mean that our nasal turbinates work in the same way as our eyes do? They have to be closed for a while in order to properly produce moisture?
As I've mentioned before, when your eyes are dry, you can moisturize them, and then they're dry 10 minutes later... It seems to be the same with empty nose syndrome patients. It seems to me that in order to restore normal moisture in the nose we need to have it closed for several hours. I think it is so, but I'd like to first find out why our eyes need to be closed in order to rest. So, I want to find the parallels between nasal and eye moisturization.


texts: Examples of points in evolution where two species stopped being interfertile?

texts:
Apologies in advance for not using the right terminology here; I'm not a biologist. This isn't for homework or anything; just curiosity.

I'm wondering: at what point do two divergent species stop being able to breed with one another, and what factors typically come into play to cause that change toward reproductive incompatibility?

I think the question above is maybe too broad, so instead I figured I'd ask for some examples of specific places in the evolutionary tree of life where this divergence occurred. I'm hoping this will give me some direction about where to start researching to find our how this typically happens in nature.

So:

Could you guys give me some examples of specific points in evolutionary history where a species was born which was suddenly unable to interbreed with its cousin species/grandparent species/etc?

Bonus points for answers with the following characteristics:

The incompatible species are very near one another in the evolutionary tree.
The species and its near-relative exist in common knowledge.
The reproductive differences between this species and its relative are significant and easy to understand.


texts:
This question is primarily about human performance. I do know about hypoxia, hence this question.

I'm busy designing a fictional region, currently in the 1930's. I have a railway line that climbs to 15,000ft (4670m) in order to traverse a mountain range. The line was build in the 1900's, with the climb being gradual at 1:100 gradient. The town on the Eastern side is at around 5,000ft. the town in the west is at about 7,000 ft. Distance by rail is about 800km, (about 10 to 14 hour journey) with about 20 to 40km spent at 15,000ft. Using real-world data,
I only have a basic understanding of the human body, and would like to ask the following questions:

1.) With 1900's to 1930's attitudes, would it be "safe" / "wise" to send passenger trains over that pass?

2.) How would this altitude affect the drivers / firemen on the steam-engine's footplate?

3.) From a biological point of view, how do I make this journey more comfortable?

4.) Any other point which I might have missed.


texts: Is Natural Selection like a Copy Editor?

texts:
I am stuck on a Homework Question. It says:

  Evaluate the following statement: “Natural selection works like a copy
  editor; it works only with
  what is already present in a population.” (Note: Copy editors check
  written material before it is set into type, to correct errors in
  spelling, grammar, usage, and style.)

I thick that Natural Selection is not like a Copy editor because:

Natural Selection has no set direction, which means it does not decide on anything. A weak organism might be able to survive by luck. While a copy editor knows the mistakes and eliminates them instantly.

Can I get some help on this. Thanks!


texts:
Can anyone please advise some possible commercially available (off the shelf) level 1 alternatives for Flu virus?
The idea is to capture this virus on a special material. So the 'replacement' should be highly similar in terms of its outer most structure and biochemistry (in terms of how it interacts externally; internal aspects should not matter). Having CTL-1 would be perfect.
Please note that I do not have any background in biology.


texts:
If a constitutive mutation happens in the operator of an inducible operon, does that mean that repressors won't be able to bind them ? Or does it mean that even if repressors are bound, they will not have any effect on the gene ?

I am specifically talking about lac operon.


texts:
Last night I discovered many ants entering my house through a window with an imperfect seal. I placed a poison ant bait on the window sill and within seconds they were feasting on it. This morning I noticed there were still many ants near the bait, but they were all bypassing it as if they were somehow warned to stay away. Do they have such a signal? If so, how would they know the bait is a problem? If not, what could cause them to be so interested last night and not interested at all today? (I can see that there is still plenty of food inside.)

Update: after a little bit more research, I decided that ants do not have a "stay away" signal, and that the only explanation for ignoring the bait would be a stronger scent trail leading somewhere else. Last night when I opened the window I found the jackpot. There was some sort of sticky substance all over the bottom of the window, and hundreds of ants celebrating the find. My conclusion is this was much more attractive than the bait, even though it was merely an inch away from their path.


texts: Why are neutral [sterile] female flowers present in inflorescences when they are reproductively incompatible?

texts:
In many compound and special inflorescences like spadix and hypanthodium there are sterile female flowers along with male and female fertile flowers and are often present in between male and female flowers, but what is their need in an inflorescence?

As far as I know inflorescences are meant for perpetuation of a plant's race by pollination of female flowers by the male gametes [pollen grains which bears vegetative and reproductive cells].

I know the infertile female flowers of the spadix inflorescence possess some surface area and this area would get some of the pollen grains which are coming in to the inflorescence, and eventually a sum of pollen grains might go in vain.

What is the need of sterile female flowers when fertile ones are present in it?