texts: When and why did humans start disliking the way we naturally smell?

texts:
Like many animals, humans produce a myriad of scents from sweating, bacteria, possibly pheromones, etc. Many of these scents are used throughout the animal kingdom for mate choice, recognition of individuals, or signifying presence or territory.

I know that humans subconsciously react to some scent cues (see here, here, or here for examples), but it seems many humans find natural human scent to, well, smell. Interestingly, this article suggests that humans' smell is worse than that of other animals.

My question is: if these scents hold so much information, how/why did humans develop an aversion to the natural scent of other humans?

Further, when did this occur? -- recently or long ago in human culture? I know Egyptians made perfumes thousands of years ago, so this is not a fully recent trend. Perhaps someone could comment on the ubiquitousness of this aversion across modern cultures as well.


texts: Why can nervous inflammation radiate symmetrically in the limbs?

texts:
I have had carpal tunnel syndrome in my hands this week, when the nerve in the pith of your palm, through thumb and index, is pinched, and swells, inside the wrist ligament tunnel.

In a few days, the inflammation declared itself in the other wrist. It's usually the case with CTS, it's rare that a person will have problems in only one had.

As soon as one hand is injured, the other tends to seize up and stop functioning as badly as the first one, within a week or so.

Why and how does a nervous injury such as CTS radiate symmetrically through the nervous system, differently from a sprain or a contusion?

What other factors in neuroscience demonstrate nervous symmetry, related to the CTS symmetry problem?


texts: Biologically, does life and death matter?

texts:
(Sorry that I'm on mobile, so I can't make a good formated question (no links). I will add them later. Just can't resist the urge to ask)

In the recent hot question about whether mitochondrial is alive or dead (it's technically dead), the top answers don't only explain whether it is dead or not, but also further explain why it doesn't matter: they just do what they need to do. This provokes me a question:

Q: Biologically, do life and death matter? Is the functionality of something the only thing that life cares?

We human are scare of death. Because of that, we tend to apply that idea into everything we can observe, even if it's meaningless. But why is death scary? Isn't it because when you die, you stop function anymore? So ultimately, isn't what we really mean when discussing whether something is dead or not the functionality of that?

Not only that, "there is no consensus regarding the answer to the question as to when does life begin". If we approach this in a different way: the time when an individual function begins to work, will there be a consensus? I mean, just don't think if an organism is alive or not, just think that how much functions of it have started to work.

If we are the combination of the numerous of selfish genes, would "humanity" be a collection of functions?


texts: What is the difference between SOLiD, 454, and Illumina next-gen sequencing?

texts:
I've started teaching myself about next-generation sequencing in preparation for a new job, and I'm wondering what the main differences are between the 454, SOLiD, and Illumina/Solexa machines, in terms of sample/library preparation and chemistry. How difficult is it for a protein veteran but next-gen newbie to get high-quality useful reads? I'm mainly going to be looking at antibody diversity, but consider this in general terms for any next-gen project.

I understand the basic theory of fluorescent chain-termination sequencing, but it's been a number of years since I last did it, and my career is now taking me back into the DNA realm.


texts: Is there a color changing organism that is by default translucent or otherwise "colorless"?

texts:
To illustrate a point I am trying to make in a paper I am writing it would be helpful to have an example of an organism that by default has "no color" but which can adopt the color of something in its environment (e.g., through some chameleon-like color changing ability or something like the food-derived pigments that give flamingos their pink color). I could just make up such an organism for illustrative purposes, but it would be nice if there were a non-contrived example.
By "no color"/"colorless" I'm thinking of something like translucency/transparency, but I can be flexible about the exact meaning so long as it can plausibly be construed as involving a lack of color.
Is there an animal that by default is colorless/transparent/translucent but which has the ability to take on colors present in its environment?


texts: I see various exposure limits for carbon monoxide, but what about one breath?

texts:
I see exposure limits for carbon monoxide like 50 ppm over 8 hours. This would correspond to a total inspired volume of carbon monoxide on the order of a few hundred milliliters. This exposure is supposed to be far from fatal, but I'm unsure how to think about extrapolating long term exposure limits to acute limits, thus my questions:

What are the likely consequences if I breathed in the entire 200 ml of CO in a single breath, or even an entire lungful of pure CO?
If the answers to the above end up being "you would die", is there a reasonable way to estimate the maximum volume you could acutely breath in?


texts: Confusion about the construction of the rat's mental map

texts:
I'm reading the article "A Topological Paradigm for Hippocampal Spatial Map Formation Using Persistent Homology" by Y. Dabaghian, F. Mémoli, L. Frank, G. Carlsson

I try to understand the following graph:

In part a) of the graph, we are seeing a bunch of colored points. These points are in the hippocampus of the rat as opposed to the idea that these points are in the plane on which the rat is moving, and so each point is a place cell of the hippocampus that has fired at some moment in some place of the plane on which the rat is moving. Normally there is a huge number of points in this picture but we chose to put only those who fired, those who did not fire are deleted from the picture of part a). Also, each point (which means each place cell) has one color, and two place cells having the same color designate that the two place cells are considered identical and will be treated as a single place cell in the part b) of the figure.

In part b), we record the time at which each point has fired, with each point being represented by a bar on the time axis and all the bars are identical (same height, and same thickness).

In part c) the picture is in the plane on which the rat is moving as opposed to the idea that the picture of part c) is in the hippocampus of the rat. In part c) we are trying to derive the place fields from part b). Deriving the place fields means here that we are deriving the path that the rat has taken. In particular, place fields are in the plane on which the rat is moving and not in the hippocampus, and each place field in the plane is determined by seeing which place cells in the hippocampus has fired at that area of the plane.

Is my understanding correct? I'm not a specialist but I need to understand each detail of this graph because my work depends on it. My confusion comes from the fact that there are two regions here: the hippocampus of the rat and the plane on which the rat is moving and I need to be sure in which region the picture is.


texts: Should the fly rules of starlings flock belong to proximate reason or Ultimate reason?

texts:
Since for Proximate (or mechanistic), causation it should explain how actions occur in terms of the genetic, neurological, hormonal, and skeletal–muscular mechanisms involved. But fly rules does not belong to any of it.

However, for Ultimate (or evolutionary) causation, it should based on their evolutionary consequences and history.

So I am really confused, the three fly rules belong to which explanation.

Thank you!


texts: Why does it take so long to bleed after accidentally cutting yourself?

texts:
Sorry if this is not a good site to ask this question, but I recently accidentally cut myself while chopping onions (very minor, no serious harm done), and noticed that it took quite a while before any blood appeared.  It probably took around 15-20 seconds before I witnessed any blood. And once the blood appears, it certainly flows consistently.

This is not the first time I've noticed this, but have often been curious why blood doesn't just start spurting out immediately.  What is the physiological explanation for why after a tissue is cut, does blood not instantly start coming out of the wound?  Naively I would assume that given that your heart is pumping one to times per second, blood flow to the wound would happen very quickly.


texts: Which landmark paper first described the differentiation of T-cells?

texts: T-cells are distinguished from B cells in part by their locus of differentiation/maturation (thymus). This is textbook knowledge, but I was wondering which particular person or people were responsible for making this discovery. I'd appreciate any links to their original papers/works. Thanks a lot!


texts: Can varied temperature while sleeping help quality of sleep?

texts:
I read an interesting article which is about relations between body temperature and quality of sleep.
I'm interested in the phrase from the article.

  Other experiments that varied the ambient temperature—decreasing it early in the night and increasing it in the morning—have shown similar benefits for improving and maintaining sleep.

So I tried to find papers and experiments but it seems my searching ability is pretty poor. I can't find it. Is there someone knows the latest knowledge or papers about this?

plus) In the article, why increasing skin temperature by 0.4 Celsius make core temperature low?


texts: How to download different kinds of data from NCBI eutils?

texts:
I have been researching NCBI eutils and wish to get some 'big data' from it. I know that I can construct queries to query one of (I think) 8 databases, like this:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/einfo.fcgi?db=nucleotide&id=2765657

which queries the nucleotide database for an id 2765657.

I am looking for a query that will return:

genetics sequences.
functional annotations of the sequences (e.g. exons, introns)
metadata (e.g. chromosome)

Would anyone be able to show an example of how to search the eutils to get samples of records as described above?

I would need to know:

Which database to search?
how to list available records?
how to query for a sample of the records?

Any help would be greatly appreciated.

Many thanks.


texts: What's the difference between proliferation and diffusion when talking about changes in tumor density?

texts:
Cell proliferation and cell diffusion seem to be important quantities to estimate when trying to understand or measure tumor growth, but I don't really understand a) the difference between them or b) their relationship to tumor growth.

Cell proliferation refers to cellular subdivision. This doesn't necessarily mean tumor growth because something can subdivide but still have the same net mass, right?

Cell diffusion on the other hand, refers to changes in cell density. Supposing cell proliferation is constant and we have positive diffusion, that would mean that cells are 'spreading out' (ie the mass is less dense but bigger). Is this correct? Would positive diffusion be equivalent to tumor growth?

This question came up when reading this paper. It talks about estimating diffusion and proliferation parameters in order to solve the reaction-diffusion equation which is, in turn, used to model tumor growth.


texts: Disadvantage of using Drosophila for breeding experiment

texts:
What should be the disadvantage of using Drosophila for experiments?

a)small size of larva.
b)short life cycle.
c)mating soon after emergence of flies.
d)large number of offsprings.

Options (b) and (d) should be advantages.

I think that the answer should be (a) as small larvae would be difficult to maintain.

Given answer is(c).

Why is that?


texts: Is there evolution in humans since the first homo sapiens sapiens

texts:
Has the human species changed since first defined as homo sapiens sapiens?

I'm asking this question partly because I'm wondering how we might evolve next.


texts: Do voltage-gated channels in a neuron use ATP

texts:
I have a question about action potentials in a neuron.
Do voltage-gated sodium and potassium channels use ATP? I mean when they are closed or when they want to open the gate, do they use ATP?


texts: Degenerate primer design for DIG in situ hybridization

texts:
New to molecular and have learned to design primers from google/youtube so any info would help

Would someone be willing to share their protocol for degenerate primer design?

Breakdown:
Trying to design degenerate primers to amplify/clone specific GPCR genes from an unsequenced genome of a particular fish.

I'm using Ensembl and Genbank for sequences of closely related fish but the complete gene has only been sequenced in 2 other fish species.
I use ClustalOmega for alignment. Is it okay to just use 2 other species for generating degenerates?

1) are there any other good databases for gene sequences?


texts:
I have a test in my upcoming Neuroscience class, one of the items on the study guide is:

Identify 2 means by which a maintained, constant stimulus produces only a transient excitation of the Pacinian corpuscle (phasic receptor). How does adaptation occur?


texts:
I am trying to visualise possible ranges of frequencies from different structures of heart:

different valves and their possible frequencies
heart sounds I - IV and their normal frequencties
what can frequencies be in healthy situation for adult
what can frequencies be in healthy situation for children 4-9 years old

I searched meta-analysis, clinical trials and reviews in PubMed unsuccessfully.

Is there any review article or book about the frequencies from different structures of heart?

Search terms used

frequency heart
frequency heart valve


texts: How are integral monotopic proteins synthesized? Is it the same process as a transmembrane integral protein or are they different?

texts: In a book I was reading, they state that secretory proteins and integral transmembrane proteins are synthesized in the same manner. But, they don't mention how integral monotopic proteins are synthesized, and when I look it up, nothing really comes up other than the difference between a transmembrane and monotopic protein. I just wanted to confirm if its process was the same or varied.


texts: If the IAVI G001 HIV vaccine proves itself, why would it work?

texts:
The IAVI G001 HIV vaccine trial looks promising.
If it works, will it work by preventing a single cell from being infected, or by allowing the body to attack infected cells?
What I'm trying to understand is if a person living with HIV for years can't develop immunity, why might the vaccine succeed?


texts: Meaning of arrows in 3D representation of proteins

texts: Below is a three-dimensional representation of the protein, CD4. I would like to know what the arrows and the thin wires between them mean.


texts: Cousin Marriage from genetics point of view

texts:
In most societies marriages between cousin are viewed negatively, due to a fear of "bad genes".
But lets say I am a girl and I marry the son of my mother's brother (i.e. my uncle), than there is no gene similarity.
Then I have two X-chromosomes, where one came from my father and the other one from my mother. My cousin (the son of my uncle) will have one Y-chromosome from his father and one X-chromosome from his mother (wh o is unrelated to me). My mother will also not be a carrier of my cousins Y-chromosome (since she is a female).

Does this all mean that this particular cousin marriage is unproblematic, and no different than a marriage between completely unrelated people?


texts: Advantage of cup-like shape of blood cells, spores?

texts:
Mold spores sometimes have the same shape as platelets in blood. If I were designing a spore it would probably be spherical. Is there any advantage to this cup-like shape?

Maybe there is some advantage in flow properties in fluid or air? And maybe the physics of structures on that scale differ from that of everyday objects?

Thanks.


texts: Is iodised salt harmful to the lactofermentation process?

texts:
I was discussing sauerkraut recipes with someone on IRC a minute ago, and they warned me not to use iodised salt in the process. My first (and so far, the only successful) batch is one I made with iodised salt - I think it's pretty much the default here. Searching the Internet shows roughly equal numbers of answers going either way, from "it doesn't matter" to "it discolours the vegetables" to "it kills the bacteria you want".

Clearly elemental iodine is nasty, as are any of the halogens. But is the iodide ion similarly harmful to the bacteria (and yeasts?) involved in lactofermentation, in the low quantities in which it's present in supermarket salt?


texts: Why do I see an inverted image of an object when I close my eyes?

texts: If I stare at an object for a long time and close my eyes, at first I can still see the object with my eyes closed. But the image I see with my eyes closed is inverted: dark colors appear as light and light colors appear as dark. Why is that?


texts: Reason behind using DNA primer in PCR techcnique while RNA primer use in replication in vivo?

texts:
I have went through Lehinger ( biochemistry book) and cooper ( cell Biology) but i didn't find my answer.
plese help me


texts:
I am trying to set up a LAMP assay (Loop-mediated isothermal amplification) for the detection of E.coli.

I was told that EDTA can chelate the Mg in my reaction and thus prevent the assay from working (similarly to PCR). Therefore, I hesitate to use TE buffer. Can I prepare my primer mix and extract DNA (using the boiling method) in DNAase free water?

will that affect the quality of my DNA and primers during storage?

Thanks a lot!

Alex


texts:
According to Wikipedia the h1 receptors stop firing to effectively manage sleep.  Assuming I understand how blocking and non blocking receptors work would a full agonist on the h1 receptors effectively prevent sleep instead of create it.

  The histaminergic neurons of the tuberomammillary nucleus become active during the 'wake' cycle, firing at approximately 2 Hz; during slow wave sleep, this firing rate drops to approximately 0.5 Hz. Finally, during REM sleep, histaminergic neurons stop firing altogether. It has been reported that histaminergic neurons have the most wake-selective firing pattern of all known neuronal types.


texts: Is the theory of evolution being disproved by bats?

texts:
For some species the Darwin's theory evolution makes perfect sense. I can easily imagine how, for example, the giraffe has evolved to its current appearance: the natural selection was favoring individuals that could consume more vegetable food from trees using longer necks, and some individuals were getting at birth necks longer than average by pure genetic randomness and the long neck trait was being propagated to descendant individuals by means of genetic inheritance. I have no problem with understanding this kind of evolution.

Now let's have a look at the bat and its relatives. The bat is one of the few mammals that have something to do with flying and the only one that took flying to the bird level. Paleontologically, first mammals date to the dinosaur era and initially looked similar to the present-day shrew (which looks much like a mouse). The question is: how in the world prehistoric mouse-like creatures could grow wings over time? It impossible to believe that some mouse-like individuals were getting wing-like limbs by mutation and the "wings" were growing out accompanied with the knowledge of how the "wings" can actually be used. Ok, then maybe first wings were tiny moth-size wings and then grew larger? But where natural selection would come into play in this case? Such mouse-like individuals would have no advantage over their wingless relatives and thus would not be able to transfer those wing-growing genes to their descendants, quite the contrary, such individuals with useless mutations that interfere with their ability to walk would be suppressed by natural selection and therefore "weeded out".

So what is the story behind the bat's wings and is the Darwin's theory really able to support it?


texts: How different are these terms: Phylloclade, Phyllode, Cladophyll and Cladode?

texts:
We started with Plant Morphology in class (specifically, the morphology of angiosperms).

My teacher's provided us with the following terms and their definitions.

  Phylloclade

  A modified stem that is flattened or cylindrical and capable of unlimited growth. They are green and capable of photosynthesis. Examples include; Opuntia, Epiphyllum, Casuarina, Euphorbia.
  Cladophyll (also called a Cladode)

  A modified stem capable of limited growth. They are green and capable of photosynthesis. They bear an axillary bud at the their middle, from which flowers develop. Examples include; Ruscus, and some Asparagus species.

 No mention of the term "Phyllode"...yet.

Now I'm sure I understand the definitions provided, however, I'm beginning to seriously question the validity of those definitions.

Apparently, these terms aren't documented very well, and after two hours of constant Googling, I arrived at:

  Phylloclade (From the Wikipedia page of the same name)

  Phylloclades and cladodes are flattened, photosynthetic shoots, which are usually considered to be modified branches. The two terms are used either differently or interchangeably by different authors. [Examples provided]: Ruscus, Phyllanthus and some Asparagus species.
  Cladophyll (From the Wikipedia page for "Petiole")

  In some plants, the petioles are flattened and widened, to become phyllodes or phyllodia, or cladophylls and the true leaves may be reduced or absent. Thus, the phyllode comes to serve the functions of the leaf. [Examples provided]: Some Acacia species.

This is annoying, seriously.

According to the definitions provided by my teacher, we're dealing with something called a "Phylloclade" and something else called a "Cladophyll" (= "Cladode"). They don't mention the term "Phyllode", though.

Based on the Wikipedia definitions, however, we're dealing with something called a "Phylloclade (= "Cladode", if you ignore minor d̶i̶s̶r̶e̶p̶a̶n̶c̶i̶e̶s̶  differences in their definitions, which are mentioned later on in the Wikipedia article), and something else called a "Cladophyll" (= "Phyllode")

My questions:

1) What are the correct definitions of the terms "Phylloclade", "Phyllode", "Cladophyll" and "Cladode"?

2) Are the examples (provided in my notes and the Wikipedia articles) actually relevant/correct? For example: Does Ruscus possess  Phylloclades (as suggested by the Wikipedia article) or does it possess Cladophylls (as suggested by my teacher)?

3) Building on question (1): Does "Phylloclade" = "Cladode", and "Cladophyll" = "Phyllode"?


texts: What kind of technology is required for plant seed DNA printing?

texts:
I'm a programmer so I have little knowledge in the field of biology. However I have an interest in plants, GMOs and DNA (in terms of programming).

So, I want to know what kind of technology is necessary and what limitations there are involved in creating a DNA printer (that could print out a cell to be grown in a pot).

First, how do we print the DNA of a plant? Can we print it all from the first pair of chromosomes? I have heard we are already able to print bacteria's DNA. Is this something we would be able to achieve outside of a lab? Could it be done on commercial scale?

Second, what conditions do we need to prepare the DNA if it is not that of a bacteria but rather of a plant that would grow into a multi-cellular organism? Can we really print a plant DNA, inject it into a cell and let it grow?

Third, what is the current understanding of DNA ? Can we analyze DNA strand with digital software yet? Can we simulate how the organism will do with the DNA? And how can I start working in this field? Are there any scientific papers I can learn from?

P.S. My first goal is to make a Nepenthes Vine. I want to have a vine plant like Pothos creeping on my fence with a jugs to eat insects.


texts: Do fat people have more chances of developing nitrogen bends?

texts:
I was reading some text on deep sea physiology. I got to know that solubility of nitrogen in fat is five times that in water. The exact text from the book animal physiology adaptation and environment by Knut Schmidt-Nielsen, was:-

  The body fat, which in a normal lean male constitutes about 15% of body weight, dissolves about five times as much nitrogen per unit weight as does water

I think that having more body fat increases your body's nitrogen saturation capacity, thereby increasing the probability of nitrogen bends.
(Nitrogen bends or aeroembolism is the phenomenon in which nitrogen gas forms bubbles in the blood stream near joints and cause pain)

So can I conclude that fat people (those who have more body fat), are more likely to develop nitrogen bends in their blood stream?

I'd be grateful if anyone out there can help.


texts: Is it possible to merge the genomes of photosynthesizing and electron-transporting bacteria to make an electric cell?

texts: I had an idea of making electric current from bacteria. There are some bacteria that can photosynthesize, and some others are capable of transmitting electrons through each other. Is it possible that through genetic engineering, we could insert the genome that allows bacteria to perform photosynthesis, with other capable of transmitting electricity, and therefor making a bacterial culture, big enough to make a free energy source?


texts: What exactly are computers used for in DNA sequencing?

texts:
I've thoroughly read the Wikipedia article on DNA sequencing and can't get one thing.

There's some hardcore chemistry involved in the process that somehow splits the DNA and then isolates its parts.

Yet DNA sequencing is considered to be a very computationally-intensive process. I don't get what exactly is being computed there - what data comes into computers and what computers compute specifically.

What exactly is being computed there? Where do I get more information on this?


texts: Age-associated neurodegenerative diseases encompass Alzheimer's Disease and Parkinson's Disease. What other neurodegenerative diseases could be described as age-associated? Multiple Sclerosis? Brain tumors? What might be the criteria for defining a disease as age-associated, specifically in the realm of neurobiology?


texts: Can GFP reporting be used to track localization of peptides in the ER, Golgi, and plasma membrane?

texts:
Suppose I want to study the trafficking of a peptide throughout the ER, Golgi, and plasma membrane. An idea I had was labeling a secreted or plasma membrane integral protein with GFP and using time-series live cell microscopy to track it through the secretory pathway.
However, I am concerned that by the time everything is set up, the cell will be at steady state, which means GFP signal would be present throughout the secretory pathway, preventing me from doing this tracking.
How might I overcome this, without changing the fundamental technology (GFP reporting)?


texts: Are there journals for theoretical models of protein-protein interactions?

texts:
Are there respectable scientific journals for publishing models of protein-protein interactions obtained by docking simulations? I would also discuss the biological significance of the particular mode of docking that I found through the simulations, and how it is consistent with available experimental evidence. The point is that my paper wouldn't have any new experimental evidence. Rather, I analyze existing experimental evidence in the literature and demonstrate that the model of interaction I propose explains this data. Are there respectable journals accepting this type of research? Can you post some example journals like this?

Also, can you post some references to good papers like these, hopefully highly cited, if there are any?


texts: Does Usnea (Old Mans Beard) have negative effects on the respiratory system?

texts: Being a fungus does it have negative effects similar to that of mold, especially on the respiratory system?


texts: Negative feedback in the fructose metabolism in liver

texts:
What happens in liver when large amount of fructose is consumed?

I vaguely remember my biochemistry lecturer telling us that the enzymes that process fructose in the liver does not have negative feedback to control the rate of reaction. But I cannot find a reliable source. How is it regulated if it is?


texts: How does drug-induced photosensitivity work?

texts:
Some drugs (tetracyclines, for instance) can cause photosensitivity reactions—that is, some patients become extremely sensitive to the sun, developing rashes or inflammation after spending time in bright sunlight. Sources I've read describe this as an immune reaction similar to an allergy, but I've also heard that antihistamines are generally ineffective at treating such reactions.

So my question is, what are the biological processes behind this reaction, and how does it differ from a normal skin allergy that could be treated by antihistamines?


texts:
I am aware about some basics of saltatory conduction of nerve impulses. I know that the nerve impulses (ion flow and the depolarization) are transferred from node to node in myelinated nerve fibers. In non-myelinated fibers, the ion flow and depolarization are repeated along the entire length of the axon. Thus the saltatory conduction is faster.

Why is it so that myelinated nerve fibers require less energy of activation then the non-myelinated ones?

Also, my book says that a rise in temperature accelerates the conduction of nerve impulses. I would like to know the reason for this.


texts: Success of computer simulations in biology, new discoveries

texts:
In an interview with Tim Hunt, Hunt makes the following comment:

  There are some people nowadays who think you can sort of model everything on a computer. But I'm not one of those. I don't think anyone has actually discovered anything modeling something on the computer because there are so many different way of doing things...how Nature herself actually chose to do it.

The claim starts at 4'25'' in the link interview.

Have biological simulations ever led to biological discoveries? What purpose have they served?


texts: Measuring Gross Primary Productivity (GPP) using Light and Dark Bottle methods: Sample Question

texts:
The following question is taken from my Cliffnotes AP Biology 4th edition practice exam and it deals with the light and dark method for measuring gross primary productivity.

  In a classroom investigation, students filled two bottles with pond water containing only photosynthesizing organisms. They used a dissolved oxygen (DO2) sensor to measure the amount of dissolved oxygen in each bottle. One bottle was put under a light. The second bottle was wrapped with aluminum foil to block all light and was put under the same light. AFter 24 hours, pond water DO2 in the two bottles was again measured. Average values for DO2 from all students are provided in the following table.

  Calculate the gross primary productivity for the observed sample. Express your answer in mg fixed carbon/L/day to the nearest hundredth.

Okay, so I know that net primary production (NPP) is the difference between gross primary production (from photosynthesis) minus Autotrophic respiration (Ra):

NPP = GPP - Ra

I also understand that the light bottle is measuring NPP, because it allows for both photosynthesis and cellular respiration. The dark bottle measures Ra because it only allows for respiration. Therefore, GPP can be calculated by rearranging the formula:

GPP = NPP + Ra

Calculating the difference in the final and initial values for both bottles, I get the following:

  Light: 0.15 mg O2 / L   <-- NPP

  Dark: -0.08 mg O2 / L   <-- Ra

Next, I plugged these into the formula:

  GPP = 0.15 - 0.08 = 0.07 mg O2 / L

Using the conversion formulas provided on the College Board's AP Bio Appendix (essentially just multiplying the mg O2 / L value by 0.374128 to get mg Carbon fixed / L), I get the following:

  0.07 mg O2 / L * 0.374128 = 0.02618896 mg C fixed / L

But according to my review book's solution, I was supposed to add 0.08, not subtract it. This seems a bit strange to me. Is this a mistake in the book or am I not understanding something?


texts: Multiple transcripts encoding for one protein

texts:
Trying to get a better understanding of the process of DNA to proteins.

So when we have a gene, it is read from the 5' to 3' end, only translating the exons to mRNAs. A single gene can have multiple exons, and use alternative splicing to create different transcripts. A transcript may result in mRNA (not necessarily right? Also other kinds of RNA?) which is translated to amino acids. Finally folded to a functional protein.

My question here, are there different transcripts (say in different genes) that encode for the same protein?


texts: Long-term viability of induced parthenogenesis

texts:
Short version:

Some parasitic bacteria, such as Wolbachia, cause hosts from sexually-reproducing insect species to reproduce asexually instead, with an all-female line. Sometimes, all members of the species end up reproducing in this way - see e.g. Encarsia formosa wasps. How many generations can this remain viable before the effects of

reduced genetic diversity/inbreeding
possible reduced parasite resistance
etc.

take their toll?

If that's too vague a question, what is the longest time/no. of generations that induced-parthenogenetic species have been known to survive?

NOTE: This only applies to induced parthenogenesis resulting from e.g. parasitic bacteria infections. Not to naturally-occurring parthenogenesis.

Full version:

Certain parasitic bacteria, such as Wolbachia can induce thelytokous parthenogenesis in their haplodiploid insect hosts. The infection is passed on down the generations, from mother to daughters. Eventually, this can lead to speciation.

(In non-technical language... the effect of this is that infected female insects lay unfertilised eggs, which hatch exclusively into females, which later on lay unfertilised eggs which hatch into more female insects...

Members of a species which previously reproduced sexually now reproduce asexually, and the asexually-reproducing members of the species may eventually diverge so much from the others genetically that they become a separate species.)

All Hymenoptera (ants, wasps etc.) are haplodiploid.

One would expect that this would reduce genetic diversity in the infected population. A species which previously reproduced sexually, and now reproduces entirely asexually, might be expected long-term to lose biological fitness as a result of inbreeding depression. See also: "Muller's ratchet"

However, a 2001 paper investigated the effects of Wolbachia-induced parthenogenesis on Trichogramma wasp species, comparing such wasps to those that reproduced sexually and to those that were naturally parthenogenetic. Fewer of the infected wasp embryos survived to adulthood, but this was due to direct effects of the infestation on embryonic growth. Inbreeding depression was not a factor.

A 2000 paper also noted that Wolbachia can be horizontally transmitted through the sharing of a common food source, and stated:

  horizontal transfer of parthenogenesis-inducing Wolbachia among offspring of infected females offers the potential for recombination between different Wolbachia variants and thus for circumventing Muller's ratchet.

Though I think that would only apply to the bacteria, not its host.

A notable example of Wolbachia-induced parthenogenesis is the chalcidoid wasp species Encarsia formosa. I don't know how long this has existed as a distinct species. Antibiotic treatment to kill the Wolbachia can restore their ability to give birth to males.

Is there a theoretical limit on the number of generations an induced-partheogenetic species should be able to survive? And what is the longest amount of time that any such species has been observed to survive?

Sources:

Tagami, Y., Miura, K., & Stouthamer, R. (2001). How does infection with parthenogenesis-inducing Wolbachia reduce the fitness of Trichogramma?. Journal of Invertebrate Pathology, 78(4), 267-271. (Paywalled, unfortunately.)

Huigens, M. E., Luck, R. F., Klaassen, R. H. G., Maas, M. F. P. M., Timmermans, M. J. T. N., & Stouthamer, R. (2000). Infectious parthenogenesis. Nature, 405(6783), 178-179.

Stouthamer, R., & Luck, R. F. (1993). Influence of microbe‐associated parthenogenesis on the fecundity of Trichogramma deion and T. pretiosum. Entomologia Experimentalis et Applicata, 67(2), 183-192. (Paywalled.)


texts: Can we say that microevolution and macroevolution is fundamentally the same thing over different time scales?

texts:
This Wikipedia article states:

  Macroevolution is evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. ... macro and microevolution describe fundamentally identical processes on different time scales.

My question is: Is this a valid claim? Can we say that creating the genetic information for a feather is not qualitatively different from changing the colour of that feather?


texts: Where does the pain from headaches come from

texts:
I may be wrong but I have always thought that the brain doesnt have any nerve endings, so why is it we get headaches and where does this pain come from?

I have heard lack of sleep, hydration or stress can causes headaches but I am interested in why and where the pain comes from this.


texts: Can anyone please help me identify my house plant?

texts:
I know this may be an impossible task, but I am one to hope ! My mum had a house plant which had small, green, oval shaped leaves which naturally grew towards the ground (hanging plant). Once every year the plant would flower for several weeks to several months and would have little white flowers bloom. Inside the white flowers were pink baby flowers (they were tiny) and they looked like they were made of glass ! The plant did not need much maintenance and was easy to keep happy, I live in the UK.

Unfortunately my mum died last year but had given the plants to my nan for safe keeping whilst we moved house and she refused to give them back to us. I was hoping to buy one as a memento to my mum, but I cannot find it anywhere and I have no clue as to its name and I sadly do not have any photos. Can anyone help me at all please ?

Thank you,
Molly x


texts: Can too low oncotic pressure lead to Third spacing and Edema?

texts:
I know that low oncotic pressure is associated with many pathologies.
I am interested how it is associated with Third spacing.
My professor says that it can permit edema formation.

The opposing pressure of oncotic pressure is hydrostatic pressure.
So that would suggests mean that the blood pressure is too high if low oncotic pressure and thus fluid would like to go to the third spacing (not sure) and edema.

Can too low colloid oncotic pressure lead to Third spacing?


texts: What's the technical difference between fainting (and being unconscious) and falling asleep (and sleeping)?

texts:
This is actually a popular question along google results but the answers usually sound like:

sleep is voluntary (oh is it?) and healthy
fainting is result of accident and is not normal

I read those answers and I'm like: "You don't say?". So yeah, I know that falling a sleep is a result of some preparation to planned unconscious state, whereas fainting is some defensive reaction trying to protect you from moving (or maybe thinking) when you shouldn't.

But I fainted once and when I woke up it was pretty much like waking up from sleep - including the fact I don't remember the moment I fainted. This gave me an idea that maybe, if you faint in your bed, you'll just fall asleep and wake up in the morning, which would be actually pretty sweet.

Therefore my question is, what's specifically going on when you faint and when you fall asleep. Is there any part when these two situations merge and the final state is the same - you're asleep?

And to my original idea: If you hold your breath to the point where you faint in your bed, what will the result be?


texts:
Firstly I could do with a brief description of mitochondrial DNA. How does the structure of DNA in mitochondria compare to animal DNA (for the sake of simplicity let's say human - some animals might have unusual DNA structure) and what living organism is the mitochondrial genome most akin to? (Circular like bacteria maybe?) and are the mitochondria within a single human homogenous?

Secondly, and most importantly to my aim, does the mitochondrial genome recombine in anyway? Is the process of recombination affected by its structure? Are there any patterns/rules in mitochondrial recombination? Is there DNA transfer between mitochondria which could have a similar effect?

I am trying to think about how male deleterious alleles can spread differently in diverged populations given potential recombination to female beneficial (or recombination away from female deleterious mutations).


texts: Does light from the left visual field reach the temporal left retina?

texts:
A diagram of the visual pathway is shown here. Light from the left visual field reaches the left nasal retina and the right temporal retina. On the other hand light from the right visual field reaches the right nasal and the left temporal retina.

The optic fibers from the nasal parts of the retina cross, whereas the fibers from the temporal hemispheres don't. This configuration leads to the projection of the left visual field to the right occipital cortex and vice versa.

My question is, why can't light from the left visual field reach the temporal left retina and vice versa? I have illustrated this in the picture below with blue arrows.

Obviously, if it would, it would interfere with the normal pattern of projection. Now my question is what prevents light from the left field of view reach the left temporal retina? Or is there some overlap between the visual fields?


texts: Will breathing through mouth result in any disorders?

texts: My nose is slightly bent. When I was born, I had an issue with breathing. My mom said that doctors had inserted a breathing tube in one of my nostrils. This tube may have caused the deformation. From childhood, I breathe through my mouth. Will there be an any problems in the future? Do I have to take any treatment? Please suggest.


texts: Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

texts:
Succinate dehydrogenase is attached to the inner mitochondrial membrane. All the other enzymes of the Krebs cycle are located within the matrix of mitochondria, though.

In biological systems, there is often a relation between structural properties and function. For example, two enzymes that function sequentially in a metabolic pathway are sometimes held in close proximity to one another by a scaffold  (e.g., in fatty acid synthesis). Is there a similar biochemical reason why succinate dehydrogenase is attached to the inner mitochondrial membrane, as opposed to being dissolved in the mitochondrial space?


texts: I live in central Ohio and found these mushrooms growing on our 10 acre property. What is it and are they edible?


texts: What did dinosaurs evolve from? Was it the reptiles that evolved from amphibians? I have been researching this but am very confused with who their direct predecessor was. Amphibians evolved from fish...reptiles from  amphibians...dinosaurs from reptiles (?)...and birds from dinosaurs. That is my understanding, but it could be wrong. How are dinosaurs related to reptiles? And if they did evolve from reptiles, which kind of reptiles (such as lizards, crocodiles, or turtles for example)?


texts: What program was used to create this visualization of a neighbor-joining tree?

texts:
I know there are many programs out there to visualize neighbor-joining trees in phylogenetics. I have a tree in Newick format. Does anyone recognize the features of this image as coming from a particular visualization program? I have tried several that may have produced this but with no success yet.

Note: I have to visually compare a new method's NJ tree with the result shown here, so that is why I really want to know exactly what program was used. This is not a question about software recommendation or opinions. Thanks!


texts: How isolated are different areas of the brain?

texts:
I'm interested in understanding how isolated different parts of the brain are from each-other. I'm trying to understand the way that different sections of the brain work together.

More specifically, I'm interested in whether or not the different sections are all intertwined together into a wild mass, or work in a more isolated way:

Do different specialized areas of the brain have specific, consolidated connection areas where they exchange information (sort of like they do their job and pass on the necessary information to the other modules)?

Or do they instead mesh very thoroughly, connecting freely to other parts of the brain sort of like tangled string, with no obvious points of consolidated interaction?


texts: Is human face more resistant to cold than other body parts?

texts:
Walking outside tonight in -15˚C I realized an interesting observation: While I felt cold on most part of my body, my face (although the only uncovered part) didn't really feel cold. It registered the temperature of course, but it wasn't a negative perception.

I wonder, what is an explanation? Is it simply because our faces are used to the cold, because we almost never cover them? Or is it some evolutionary phenomenon?


texts: Does cartilage connect to other cartilage?

texts:
In the definition of a Ligament in Oxford states:

  A short band of tough, flexible fibrous connective tissue which
  connects two bones or cartilages or holds together a joint.

the wording of "two" prior to bones or cartilages sounds like it could be bone to bone, cartilage to cartilage, and bone to cartilage.

Are all of these combinations correct? If so, is there a good example where each one can be seen for reference?


texts: Are there transposons which create homozygous genotypes in offspring?

texts:
Transposons copy or cut and paste gene sequences. Alleles are passed down from parents and offspring may be heterozygous or homozygous for an allele (assuming diploidy).

Are there any transposons which ensure the frequency of a given genotype in a population by converting heterozygous zygotes into homozygous zygotes?


texts: What causes the tonotopic organization of the inner ear?

texts:
I'm trying to understand why tones are registered in the way that they are in the inner ear, i.e., why are high pitched sounds sensed at the base of the cochlea and low frequencies in the apex? I've been unable to find out the specifics of this tonotopy, but as far as I can gather this is due to the physical properties of the basilar membrane.

But what exactly are those physical properties? Does the basilar membrane vary in size and stiffness along its length, so that each bit has its own resonant frequency, or is there something else going on?


texts: Why are the largest land/air animals today smaller than in the Mesozoic?

texts:
The largest dinosaurs and pterosaurs seem to have been much larger than the largest animal terrestrial/avian species since. Was the Mesozoic somehow more hospitable to large animal species than today's world? Have subsequent evolutionary innovations shifted the balance towards smaller species?

Interestingly the still-existing blue whale seems to be the largest animal ever.


texts: Is egg white lysozyme different from bacterial lysozyme?

texts: Someone told me that microbial lysozyme has effect on gram negative bacteria but egg white lysozyme only affect gram positive bacteria. Is it true?


texts: Is there an epidimiological way to define rare and common diseases ?


texts: How are non-glucose sugars metabolized in the body?

texts:
In my biology book's section on disaccharide metabolism and glycolysis, it states that sugars other than glucose must be acted upon to enter glycolysis. Let's take sucrose as an example. Sucrose is hydrolyzed in the small intestine by sucrase. The resulting fructose and glucose are absorbed and transported to the liver via the portal vein. My question concerns the fate of fructose.

To undergo glycolysis, the book states that fructose is converted into either fructose-6-phosphate (F6P) or fructose-1-phosphate (F1P). Let's say it is converted to F1P. Aldolase splits this into dihydroxyacetone phosphate and D-glyceraldehyde. Triose kinase then converts D-glyceraldehyde to glyceraldehyde-3-phosphate, a glycolytic intermediate. Where is this occurring in the body? Are we still in the liver? I can't imagine that all the fructose we consume is undergoing glycolysis in the liver. To leave the liver as a sugar, it would have had to been converted to glucose, right?

In classes I've taken, I've been told that sugars that enter the liver are pretty much all converted to glucose. Once they are converted to glucose, they can be distributed to the rest of the body, stored as glycogen, etc. If we are going straight from fructose to F1P to a glycolytic intermediate, we couldn't have left the liver. How is such a transformation even useful? Anyone care to shed some light on this?


texts: Where does Darwin state his "principle of multiple utility"?

texts:
I have never heard of Darwin's 'principle of multiple utility', but several papers refer to it. For example, from Darwin at the molecular scale: selection and variance in electron tunnelling proteins including cytochrome c oxidase

  Such a high degree of conservation is probably the consequence of many parallel and concurrent aspects allied to the construction, manifold functions and demolition of cytochrome c oxidase as illustrated in the molecular scale view of Darwin's principle of multiple utility (Darwin 1872) shown in figure 7.

Also, from the pape, Engineering enzymes.

  Another source of biological complexity arises from Darwin’s principle of multiple utility. The principle originally applied to organisms recognizes that any one trait in an organism is subject to be selected by multiple forces.

The citation to "On the Origin of Species" in these paper provides no page numbers. Neither do any of the other papers that mention the principle. I searched the sixth edition of "On the Origin of Species" for terms such as utility, multiple, roles, etc., but found nothing that sounds like such a principle.

It seems to me that anything described as a Darwinian principle would be extensively discussed in the literature. That does not seem to be the case with this so-called 'principle of multiple utility'.


texts: At what point during an action potential are the sodium potassium pumps working?

texts:
I'm trying to understand how all of the potentials during an action potential are created. My question specifically is about the sodium potassium pumps, however I would also be grateful if someone could verify if I have grasped the concepts correctly.

From what I understand, the resting membrane potential is at around $-60\rm\,mV$, close to the equilibrium potential for potassium (from the Nernst equation) because the permeability of potassium is much greater than that of sodium, even though the permeability is low.

However, the resting potential is not as negative as the equilibrium potential for potassium because of some permeability of sodium and the permeability of potassium is very low so the tiny permeability of sodium has some impact in preventing the potential reaching the equilibrium potential of potassium.

When the threshold potential of $-50\rm\,mV$ is reached, the voltage gated $\ce{Na+}$ ion channels open, and sodium ions enter the cell, causing depolarisation. The potential rises to about $+40\rm\,mV$, which is close to the equilibrium potential for sodium (because the permeability for sodium is much greater than for potassium). However, it doesn't quite reach the equilibrium potential for sodium because of some potassium ions leaving the cell.

When the $+40\rm\,mV$ threshold is reached, sodium channels close and potassium channels open. Because of the now much higher permeability of potassium ions compared with when the membrane is at its resting potential, the potential becomes much closer to the equilibrium potential for potassium, which I think is about $-90\rm\,mV$, and therefore the cell hyperpolarises. Then the potassium channels close.

Now I'm unsure as to how the resting membrane potential is reached from the hyper polarised state, and I also do not see where the action of the sodium potassium pumps comes into this.


texts: Would canines that consume the stomach of ruminant prey animals benefit from any of the bacteria and enzymes present in the rumen?

texts:
This question is inspired by the growth in popularity of raw diets for pet dogs. Green tripe is a common addition to these diets, with many claims of probiotic benefits.

Here's an example from a site that sells ground, frozen green tripe for pet dogs: http://greentripe.com/

Another article with some of the claimed benefits (I already know there is some misinformation in this article - it claims that dogs don't naturally produce the enzyme amylase, but that is false) http://ivcjournal.com/raw-green-tripe/

Do these claims make sense? I know most of the bacteria in the rumen would die after being exposed to oxygen, but would the rest of the bacteria, fungi, and enzymes present in the rumen be of any benefit to a canine when consumed?

What about after the tripe has been ground, frozen, etc?


texts: How does expansion of the skin via mitosis influence the density of its specialised nerve endings

texts:
I found a reddit question Do nerves & nerve endings expand with skin or does skin expansion causes loss of nerve density where a user references the study Assessment of Epidermal Nerve Fibers: A New Diagnostic and Predictive Tool for Peripheral Neuropathies which states that intraepidermal nerves fiber density is not dependent on weight

No significant relationship of race, height, or weight on IENF density has been reported

Reasoning that if additional nerves are not generated in response to expansion of the skin, then one should expect a negative relationship between nerve density and weight.
My question is, upon expansion via mitosis, will sensitive skin rich in specialised nerve endings such as the Meissners corpuscles generate more of this same type of nerve endings?
Specifically i’m curious about the inner foreskin and innervation of new tissue created under foreskin restoration if that makes a difference

Foreskin restoration is the process of expanding the skin on the penis
to reconstruct an organ similar to the foreskin, which has been
removed by circumcision or injury. Foreskin restoration is primarily
accomplished by stretching the residual skin of the penis


texts: How do we feel sensations from a tooth surface that is made up of enamel?

texts: If enamel does not have any sensory receptors, how do we feel the tactile sensations when we touch our teeth with an object/finger nail?


texts: Why is translation so much faster in prokaryotes than eukaryotes?

texts: Prokaryotes perform transcription and translation much faster than eukaryotes. If memory serves, a single 70S prokaryotic ribosome can incorporate around 20 amino acids per second, whereas the 80S eukaryotic counterpart is much slower, at around 2 amino acids per second. Is the reason for this known? The only possibility I can think of is that prokaryotic mRNAs are often polycistronic, whereas eukaryotic mRNAs are not and tend to involve co-translational protein folding. Slower translation may be able to improve folding accuracy. Other than that, I can't think of any reason the 80S ribosome would be physically slower than the 70S ribosome. It's not like DNA replication where accuracy is exceedingly more important in multicellular organisms than in fast-replicating unicellular prokaryotes.


texts:
Normal or healthy cells have a natural ability to avoid being attacked by the immune system.
 So if a cancer cell has all inherited 'strategies' for avoiding the immune system (that are from their earlier pre-cancerous states) does this make them hard to detect or be affected by the immune system.


texts: Conversion and storage of glucose to glycogen

texts:
Why is excess glucose, synthesized to glycogen, stored only in limited amounts, as compared with lipids/triglycerides that are stored in our body?

Why is mature glycogen arranged (polymerized) in 12 tiers polymer?


texts: Are there computational models verifying the feasibility that complex biological systems can emerge by random mutations plus natural selection?

texts: I am interested in studying the theoretical feasibility that very complex systems such as the vascular system, the respiratory system, the nervous system, the digestive system, among others, could have emerged by means of random mutations plus natural selection. Are there computational models that have successfully verified (via simulation or other means) the theoretical feasibility of the Darwinian hypothesis that random mutations plus natural selection can indeed give rise to sophisticated systems under the time constraint and the environmental constraints life on Earth probably had to face? What is the state of the art (as of 2020 and later) on this regard?


texts: How have single-celled organisms learned to survive?

texts:
Upfront: I am a computer science student trying to understand evolution and its implications.

I've been pondering the concepts of evolution for some time, especially related to neuroscience / how the brain works / how to emulate brains. I wonder how single-celled organisms evolved at all. I know, they don't "think"; but once their ATP levels get low, they know they must find food to sustain their system, aka staying alive. This is probably no active decision, more like: "The enzyme concentration tells me to find food".

Question: Was the entropy just high enough that at some point those organisms had the property that finding food somehow is preferable to death? Edit: How can an organism perform something without "knowing" it needs to perform it?

I hope, this isn't a terribly stupid question.


texts: I am really confused as to when kinetochores are attached to centromeres. Are they attached soon after replication or after condensation ?


texts:
I have seen on the internet that prolonged steriod treatment can result in the development of steroid drug tolerance leading to decreased hormone secretion. In turn this may lead to drug dependence, as you need to keep taking that drug to keep your body to function normally.

Can steroid treatment lead to drug dependency, and if yes, how?


texts:
There are claims that salicylic acid has an effect on acne. I have done preliminary research and found multiple sources saying:

"Salicylic acid [can] help prevent future breakouts." - https://www.healthline.com/health/skin/salicylic-acid-for-acne
"Salicylic acid penetrates into your skin and works to dissolve the dead skin cells clogging your pores." - https://www.healthline.com/health/skin/salicylic-acid-for-acne
"Salicylic Acid works by opening the pores and killing the bacteria inside." - https://www.reddit.com/r/askscience/comments/tuqt2/how_do_things_like_salicylic_acid_and_topical/
Pointing out that salicylic acid is used to treat acne, but no explanation as to how. - https://en.wikipedia.org/wiki/Medical_uses_of_salicylic_acid
"Salicylic acid modulates COX2 gene expression to decrease the formation of pro-inflammatory prostaglandins. Salicylate may competitively inhibit prostaglandin formation. Salicylate's antirheumatic (nonsteroidal anti-inflammatory) actions are a result of its analgesic and anti-inflammatory mechanisms. Salicylic acid works by causing the cells of the epidermis to slough off more readily, preventing pores from clogging up, and allowing room for new cell growth. Salicylic acid inhibits the oxidation of uridine-5-diphosphoglucose (UDPG) competitively with nicotinamide adenosine dinucleotide (NAD) and noncompetitively with UDPG. It also competitively inhibits the transferring of glucuronyl group of uridine-5-phosphoglucuronic acid (UDPGA) to the phenolic acceptor.", again, with no source. - https://en.wikipedia.org/wiki/Salicylic_acid
"Because BHAs [specifically salicylic acid] are oil soluble, they’ll be able to penetrate deep into the sebum filling up your pores, loosening the gunk to make it easier to remove" - https://fiftyshadesofsnail.com/2015/03/28/how-to-shrink-pores-temporarily-plus-3-pore-myths/
"Salicylic acid dissolves well in vegetable oils." - https://chemistscorner.com/cosmeticsciencetalk/discussion/2514/how-to-dissolve-salicylic-acid-or-aha-acid-in-oil
"Salicylic acid helps ... by dissolving the type of skin debris that clogs pores and causes acne" - https://www.huffpost.com/entry/heres-exactly-what-salicylic-acid-does-to-your-skin_b_578cff25e4b07cc1115aa329

Therefore, the sum of claims add up to that salicylic acid

Penetrates skin.
Dissolves dead skin and skin debris.
Separates skin.
Opens pores.
Reduces inflammation.

If I suppose the anti-inflammatory properties of salicylic acid is well-documented by virtue of being similar to acetylsalicylic acid, then 5) can be intuitive. My remaining questions are as follows.

How does salicylic acid penetrate skin? Which part of the skin? What does it do there? How does it penetrate skin better than other amphiphilic molecules?
How does an acid dissolve dead skin and skin debris? How much acid, at what concentration, at what temperature, and for how long?
Through what mechanism does salicylic acid "open pores"? Additionally, if opening pores is one of its selling points, is it not true that ordinary soap also removes dirt from pores?


texts: Found on Cape Cod MA near a fresh water pond with a muddy bottom. Strange looking creature with a suction cup single "foot" with a mouth opening on opposite end, no limbs, mouth ridges inside mouth, spiral rings of tissue up entire body. Any idea what it is? I thought it might be a tunicate of some kind but I can't find a match anywhere.


texts: What are some online databases that I can search to find the pathways for sythesis of Lignin, Cellulose, GAX?

texts: I am trying to obtain the pathway information for synthesis of Lignin,GAX and Cellulose in Sorghum. I am quite new to biology and genetics (EE background). I would appreciate it if y'all can provide me with some websites or books where such info maybe available. I have already looked in KEGG. Thank you very much.


texts: Is it possible to induce protein activation via frequency-specific mechanical waves?

texts: Would it be possible to induce shape changes in specific proteins by providing specific frequencies of mechanical waves in a thermostatically controlled environment such that those proteins may be activated without requiring regular ligand binding?


texts: why monocot roots have a wide pith while dicot roots have a narrow pith?

texts: Normally dicot roots have a nartow pith at the center but monocot roots have a wide pith. Is there any specific reason to this?


texts:
What Websites Have Image Libraries for Bacteria and other Microorganisms?

With age of cell phone microscopes and hand held spectrometers it would be interesting and valuable to be able to compare in-home/at-work microbiology with data-banks. To be able to test for health or enjoy the visuals of tree of life seem relevant. What websites are out there?


texts: Dark and bright sides in fluorescence microscopy images?

texts:
I have used Phalloidin to label F-actin in ethanol fixed cells ( I know formaldehyde might have been a better choice for fixation). I am new to new to this and I am experiencing that one part of image is bright while other portion is dark (please see attached image). I have already checked that its not due to the lever which we use to shift from bino mode to image mode (eye to camera mode). i have captured images previously and they looked perfect.I dont know what's wrong? Does anyone know what might be the problem?
As I said, I am new to this so it might be a very stupid question but I preferred to ask.
Thanks in advance!
Best,
Ankur


texts: evolution and mutation of microrganisms against medicines?

texts:
I presume microorganisms would have very short life span and they would multiply more creating millions of their kind. Is it really a threat to consider when we use anibiotics and other stuff more making these creatures becoming resilient to the medicines. On the other hand bodies becoming dependent on the medicine making us weaker .we clean our office spaces homes etc with bleaching agents, acids killing microorganisms and thus making our body unaware of these and letting these organisms survive and create more deadly strains.

I believe there are examples like malaria microbes becoming resistant to quinine perhaps many more.  If someone tries not to take medicines when he suffers from common cold and small fevers and let the body fight but is it right to do so considering that mecines are available and one should take them.

There is an article also published today.


texts:
Is there any explanation why we have two brain hemispheres? Is there any advantage of having two in contrast to having one (or three / four)?

From what I've read so far (not too much; I'm not a biologist) each half can take the job of the other half when it comes to injuries. Is that correct?

Are there animals which have more than two hemispheres?

edit: I have seen What was the evolutionary reason for cross lateralization of the brain?, but that question seems to be about the question why the left hemisphere controls right body parts and the right hemisphere controls left body parts. My question is why there are two hemispheres at all.


texts: How to selectively download 3 fields from every record in UniProtKB?

texts:
I want to download a comprehensive table of protein names from uniprot.org.

More precisely, I want to generate a tab-delimited table consisting of the id (accession), entry name, and protein names "columns" from the UniProtKB database.

I want to get these three columns/fields for all 80M records in UniProtKB, and I don't want to specify all those Uniprot IDs through, e.g., a bazillion URL-encoded queries.  Also, I need to do this from a host that I can access only through a text interface, which basically rules out browser-based solutions.

I just spent a couple of hours going back-and-forth over the Uniprot site's docs, and I can find nothing useful.  The Perl example given there1 shows how to download full records, but downloading every full record from UniProtKB would be too slow and onerous to be considered2.

Does anyone know how to modify the Perl example (or any other way) to download only the three desired columns from UniProtKB?

1 You need to click on the phrase "Perl example" to see the code.
2 I downloaded a small test sample of 1000 full records, I found that the size of the information I actually want from those records is only 0.2% of the total.  IOW, downloading the full records would take up ~500x as long as downloading only the desired information.


texts: What are housekeeping and constitutive genes?

texts:
I have come across two set of definitions which are not contradictory but different.

From wikipedia:

  A constitutive gene is a gene that is transcribed continually as opposed to a facultative gene, which is only transcribed when needed.

  A housekeeping gene is typically a constitutive gene that is transcribed at a relatively constant level. The housekeeping gene's products are typically needed for maintenance of the cell. It is generally assumed that their expression is unaffected by experimental conditions. Examples include actin, GAPDH and ubiquitin.

My question from these definitions: What does 'transcribed at a relatively constant level' mean? Does it mean that a constant level of gene product is maintained in a cell? I can't understand there meanings atal.

Again,according to Oxford dictionaries

  Constitutive Genes are genes that are expressed following interaction between a promoter and RNA polymerase without additional regulation.
  (Oxford Dictionary of Biochemistry and Molecular Biology)

  Housekeeping genes - Constitutive loci that are theoretically expressed in all cells in order to provide the maintenance activities required by all cells: e.g., genes coding for enzymes of glycolysis and the  and the citric acid cycle.(Dictionary of Genetics)

These definitions do not tell whether they are continually transcribed or the synthesised products are present in constant amount.

Which one best define them?


texts: How do environmental conditions differ between nitrogen fixing bacteria and denitrification bacteria?

texts:
I am currently experimenting with aquaponics and need to better understand nitrifying and denitrifying bacteria.

From my research it seems that both varieties are anaerobic. From an engineering perspective, how would I control the environment such that nitrifying bacteria would dominate a water medium or vice versa? I'm thinking some combination of the following should provide some level of control; pH, temperature, surface area, tds, nitrogen partial pressure, concentrations of fixed nitrogen and types, etc.


texts: Does a gene that regulates itself necessarily be a transcription factor?

texts: I am not a biologist, so please pardon the overly noob question. Some genes are transcription factors (TF) and regulate other genes. My question is: if a gene is NOT a TF gene, can it regulate itself? E.g. given a system of 3 genes {g1,g2,g3} where only g1 and g2 are TF, then in a gene regulatory network, what are ALL possible parental sets of g3 (where in this GRN, you put a directed edge from the regulating gene to the regulated gene)? Will it be {{g1},{g1,g2},{g2},{}} or {{g3,g1},{g3,g1,g2},{g3,g2},{g3}}


texts: How to translate a blood type used in Eastern Europe?

texts: What are the I-IV blood type descriptions shown below (commonly used in Eastern Europe), and how do you translate them into the ABO-system?


texts: I was wondering whether all beavers, from all around the world, know how to build dams and lodges? Do they need to learn it from their parents? If you release a group of beavers in the wild that haven't been in contact with their parents, would they start to build stuff? or just hopelessly die/starve to death?


texts: How is the flicker fusion rate interpreted as an on-off rate?

texts:
In our experiment we use a fly to determine the flicker fusion frequency, i.e., that frequency where the fly starts perceiving a pulsating light as a constant light source. The human eye also has a flicker fusion frequency. For example, most people cannot see the flickering of a fluorescent tube, which equals the main frequency (60 Hz in Europe & USA).

Our experimental light source needs two input durations, namely how long the light is ON and how long it is OFF for. The input is provided in ms. From what I found out so far is that the unit Hz equals the frame rate, namely pictures per second. So a frame rate of 50 Hz is 50 pictures during 1 second.

But in my experiment it is about flashes of light, namely a light phase and a dark phase. Does the dark phase then count as a picture? So what I mean is whether 50 Hz represents 50 times lights ON + 50 lights OFF, or does it mean 25 times lights ON and 25 OFF?

Also, how long is then each light pulse?

My assumption is:
50 Hz are 25 lights on and 25 lights off within 1 second.
50 pictures in 1000 ms
1 picture per 20 ms
20 ms / 2 = 10 ms lights ON, 10 ms lights OFF


texts: Why would a 2019-nCoV protein sequence in the NCBI database match a protein submitted in 2018?

texts:
There seems to be a bit of a conspiracy theory brewing over some data in the NCBI database, and I don't have the necessary knowledge to make sense of it.

It basically goes like this:

Go to NCBI BLAST
Click on the big Protein BLAST button
Enter AVP78033 in the main search box and click BLAST
Click on the first result that shows a 100% match and click "See 5 more title(s)" in the first entry

This shows that the search is a complete match for a Bat SARS-like coronavirus protein from a 2018 research paper, for Wuhan seafood market pneumonia virus (which the NCIS site indicates is an alias for 2019-nCoV), and for Bat coronavirus from 29 Jan 2020.

My question is - why would a protein from Bat SARS-like coronavirus and 2019-nCoV be showing up as a perfect match for one another? Does this mean that 2019-nCoV might actually be a previously-discovered coronavirus that very recently started infecting humans? Or could it be that a recently collected sample from Wuhan was mis-identified as 2019-nCoV when it is actually the same coronavirus from the 2018 submission?

Clicking around the links on that site seem to bring up dozens of similar but different pages that I don't have the knowledge to distinguish, but the Accession column from the search results described above contains a link to this page, which says that it is a provisional refseq and acknowledges that it is identical to the bat coronavirus:

  PROVISIONAL REFSEQ: This record has not yet been subject to final
              NCBI review. The reference sequence is identical to QHD43418.
              Annotation was added using homology to SARSr-CoV NC_004718.3.

Can somebody who actually understands these things please make sense of this?


texts: How is epinephrine and norepinephrine different?

texts:
Is there any difference between epinephrine and norepinephrine?

https://www.quora.com/What-is-the-difference-between-epinephrine-and-norepinephrine

This site says that norepinephrine is also a neurotransmitter.

Is there any major difference between them?


texts:
According to Wikipedia,

  the outer plate... is assembled in the surface of the chromosomes when the nuclear envelope breaks down.

However is makes not mention of when the inner portion of the kinetochore forms, and I cannot seem to find this jn formation elsewhere. Is it present from DNA replication and helps to hold the sister chromatids together?


texts: Modern Classification of Introspective Psychopharmacological Drug Profiles?

texts:
In the effort to better relate neuronal mechanisms to states of mind, it makes sense to have - in addition to pharmacological classifications of drugs and imaging/physiology classifications of their effects - classifications of the states of mind they evoke, according to introspective reports.

I have been unable to find such a data-driven classification in the literature (I would imagine a cluster analysis of reported terms, or a factor analysis of ratings on statements could be appropriate). Instead, "subjective effects" classification seems to be restricted to single-substance profiling, and elsewise is remarkably top-down - based on ad hoc models by the same authoritative people or entities which commonly make psychoactive substances available to consumers (introducing confirmation bais). I'm wondering if there's anything else out there?


texts: Absorbed dose from a CT scan with relation to radiation accidents

texts:
I read somewhere that the average CTDIvol in CT scans at hospitals is ~40 mGy. This translates to the 'radiation intensity' at the center of the person, and can also be roughly interpreted as an 'absorbed or equivalent dose', but this is not the organ specific absorbed dose.

From medical literature, particularly the life span studies of RERF,  I read that at 2500 meters the 'absorbed colon dose' was about 5 mGy [1].

Out of curiosity, I tried to figure out at what distance you would have to be from the epicenter of Hiroshima, to get the same level of 'absorbed colon dose' as the average CT Scan.

To convert, the ~40 mGy to 'absorbed colon dose', you use a tissue weighting factor [2]. The tissue weighting factor for the colon is 0.12. So, this means, the average CT Scan results in an 'absorbed colon dose' of ~40 mGy * 0.12 = ~4.8 mGy.

I realize there is a different concept of 'effective dose' that calculates risk of cancer based on organ type and organ weight scanned. That is not of interest for my calculations.

As far as purely 'absorbed dose' of the organs is concerned, is it accurate to say that the the average CT scan has the same effect on a person's organs as it would to someone standing just outside 2500 meters from the epicenter of Hiroshima?

[1] http://www.rerf.jp/general/qa_e/qa2.html
[2] https://www.euronuclear.org/info/encyclopedia/t/tissue-weight-factor.htm


texts:
This article states:

  Once the neural tube closes, at around week 6 or week 7 of pregnancy,
  it curves and bulges into three sections, commonly known as the
  forebrain, midbrain and hindbrain. Just to the rear of the hindbrain
  sits the part that will soon turn into your baby's spinal cord. Soon,
  these areas bubble into those five different regions of the brain that
  we're most familiar with: the cerebrum, cerebellum, brain stem,
  pituitary gland and the hypothalamus.

How "soon" after 6 - 7 weeks is this soon the article talks about? When does the brain stem appear in humans?

Fetal Brain Development


texts: 293T safety, transfections with plasmid DNA

texts: I am a little concerned with 293T cell lines, I have been working with this cell line for a few years with less frequency. However there were times that i extracted the proteins from these cell lines outside the hood. I never work with virus, i have only transfected plasmid DNA. can someone help me if there are any chance o exposure, if yes, how dangerous is it.


texts:
There are three types of barriers, physical , climatic and biological barriers that can prevent the dispersal of organisms.

Topographic barrier falls in the category of physical barrier but exactly what should be considered as topographic barriers is not clear to me.

The source from which I actually came across the term says that mountain range is a topographic barrier like the Himalayan range separating the North-asian fauna (partly Palearctic fauna) from the Oriental fauna. But what else falls under topographic barriers is my question?


texts: Why Hasn't my Cactus Grown Deadly Spines?

texts:
I recently purchased a small cactus plant from my local store for about $5.

I've been giving the cactus lots of sunlight and a good watering every week.

I've noticed that since I bought it, the other cactii at the store have sprouted long and deadly looking spikes of at least 2 inches in length. My cactus has extra little clones growing out of it but its spikes are stunted and disappointing.

Why won't my cactus grow spikes?

My cactus is of this variety:

http://www.friendsschoolplantsale.com/sites/default/files/images/colors/a-flat-cactus2-ns.jpg?1364265449


texts: Why trust vaccine statistics from the mid-20th century, if ELISA tests were not available and disease diagnoses were completely subjective? Any answer is helpful. Please let me know.


texts: Does extracted DNA degrade after a certain time period?

texts:
For direct use as template in PCR runs. Chelex 100 5-10% w/v extraction. Without listing the whole protocol, in the end the supernate is decanted off and then stored at 4°C. I was under the impression that this could be stored and later used almost indefinately but two of four samples extracted several months back failed to produce a product (when it was known they should have).

Assuming no mistakes were made and the reactions were the same, is there a technical reason the template would degrade to an unusable point?

Is there a rule of thumb about how long it can reasonably be expected to last?


texts: How many synapses are there in the different target regions of a typical cortical pyramidal cell?

texts:
I found the following pictures of axon trees:

source

source (axons are red)

but didn't find a concise answer to the following question:

  How many (in relative terms) branches terminate and how many axon
  terminals (synapses) are there in the different target regions of a
  typical cortical pyramidal cell, i.e.

  same cortical layer
  other cortical layers
  same cortical column
  other cortical columns
  more distant cortical regions (e.g. in the same gyrus)
  subcortical regions


texts: Found in Belgrade, possibly carried back from the Mediterranean or Aegean coast.


texts: What part of food gives the blood red color?

texts:
Roughly, what I know is, when we eat food it goes into our: Stomach > Small Intestine > Large Intestine > Rectum. So, it just moves through a digestive pipe.

What I don't understand is, what part of the food is responsible for blood's color and how does the food that we eat mixes with blood?


texts: Does the cactus wren use a call to elicit insect prey movement and detection?

texts:
I will be referring primarily to a 2013 paper, If a bird flies in the forest, does an insect hear it?, and my own investigation. Bird flight sound frequencies overlap with the hearing range of most tympanate insects. There are several insects that possess hearing for which the function is not known and it is hypothesized that this capacity is used to avoid predation. For example, silent butterflies and grasshoppers have broadband audio sensitivity and some calling insects appear to have hearing tuned outside of the call frequency.

I have observed cactus wrens (Campylorhynchus brunneicapillus) foraging for insects on the ground outside my window (southwest desert, USA) and have noted that they invariably emit a characteristic odd periodic call while they are so engaged. You can hear my recording of one such hunting wren made April 18, 2017 here. Cactus wren foraging call

I used the open source audio processing application, Audacity, to analyze the wren call I recorded. Here is a spectrogram of the call:
.

You will note that the call is periodic at about 7 Hz. For comparison, typical pulsed bird wing sounds (the sound of bird wings as they are hovering or approaching prey) are around 18 Hz frequency. Those wing sounds are broadband bursts though, approximately 49 kHz +/- 18 kHz. I mention this because the cited paper and many others looking at bird sounds and insect hearing have explored primarily the hypothesis that it is the flight sound the insects are detecting. My own idea is that some bird species actually generate sounds within such a range in order to provoke prey insects into fleeing from hiding or a stationary position.

Typical moth and butterfly audio frequency response is given here:

(reproduced from the work cited earlier).

The cactus wren call may be seen to exhibit energy in the 1.6kHz - 2.20kHz range primarily, peaking at 1954 Hz (spectrographic analysis of exactly that portion not shown). This seems interesting given that Cyphoderris crickets call at 12 kHz, but their ears are most sensitive to 2 kHz (almost exactly the wren burst frequency peak).

I could not find research examining my hypothesis and thought I would ask the question here, i.e., is there research examining the possibility that certain bird species use calls to enhance detection of prey insects (and the related question, does this seem likely given what others may know about the subject of insect hearing, its range and uses, bird predation behavior, etc.)?


texts: I live in Utah and I'm wanting to plant some Utah native plants in my backyard. There is this wildflower everywhere in the mountains of Utah and I really want to know the name. It looks like some sort of Paintbrush (Indian, Wyoming) but I've searched for those and they don't look the same.


texts:
So with my basic understanding of biology, DNA can change over time.

Does this mean that if one (or both) parents have something major missing (like a limb), the kid will come out without a limb?  Does it matter if the parents had limbs amputated or were born like that?  If someone got melanoma from laying in the sun a lot, would their kid have a higher risk of getting it?


texts: How does a jumping spider manage to "jump" on the ceiling?

texts:
I just witnessed a small jumping spider jump on some kind of louse or bed bug on the ceiling. How does it do that without falling? I have yet to find a high-speed-camera video of a jumping spider jumping on a ceiling.

My hypothesis is that the spider would spit silk and anchor it on the ceiling, then jump, and allow itself to be swung by the silk onto the prey. But I don't have a high speed camera to prove that.

EDIT:
I now have some evidence that supports my hypothesis: I just saw a jumping spider attempt to jump on a prey and failing to land properly. It didn't fall directly to the floor. Instead, it dangled from its own silk, at about 2 cm from the ceiling, then climbed right back up the thread of silk, onto the ceiling.


texts: E. coli values for [enzymes], [metabolites] and kinetic rates

texts: In my attempt to create a metabolic model of E. coli, I have found a comprehensive list of metabolic reactions and their stoichiometry. The one I am currently using is E. coli model iJO1366 (more here). What I have not yet found is a comprehensive list of kinetic rate constants associated with these reactions. I also require a data source of concentrations of these enzymes and metabolites at steady state in E. coli. Where can I find information on concentrations and rate constants?


texts: What type of immersion oil should I buy?

texts:
I have an old Nikon Alphaphot microscope that came with a 100x oil immersion objective, but no manual. I've seen plenty of sources that explain that you need to place a drop of oil between the slide and objective, but when I went to order immersion oil I discovered that there are several different types. There's Type A, Type B (apparently similar to Type A but more viscous), and a number of specialty types. My plan is to use the microscope for projects like looking at blood cells, pond water, and other high school science project-type investigations?

Which type of immersion oil is right for all around, general purpose use?


texts: How do sharks and other fish conserve and gain water in marine environments?

texts:
With the osmolarity of the average vertebrate being around 300mOsml, and salt water having an osmolarity of 1000mOsml, why does the water from the shark not leave to the salt water around it?

I presume the scales must act as a barrier to stop water form leaving, but with the blood vessels being exposed to the saline water in the gills, why does water not leave the body?


texts: For how long can influenza survive on a piece of paper?

texts: Consider the following hypothetical: A graduate student would like to return a set of assignments before a certain deadline, but she currently has the flu and may sneeze or cough while grading the papers at home. Under the assumption that she has just graded the papers but is still in possession of them, how long should she wait before returning them to the students? At what point does the risk of transmitting the flu to a student via paper become negligible?


texts:
to begin with: I have some background in cognitive neuroscience, but have not intensely studied the biochemical background of neuronal signalling, so please correct me if my basic understanding is wrong.

As studying the generation of action potentials and EPSP/IPSP at synapses, I noticed that as those processes make use of the gradients, the actual signalling process works by resolving these gradients (i.e. the molecules flow without having a constant energy supply pushing them to do so). The big part of energy consumption during neural signalling is then actually needed for restoration of these gradients, transmitter reuptakes etc.

So if the above is correct, does that mean that the information "flow" in the brain is done by increase of entropy (which I intuitively understand as a increase of "unorderedness", but im not a physicist either...)? I have been told that biological systems actually want to resist the "natural" direction of entropy in that they want to keep themselves "ordered" to survive. I would have hence found it more intuitive if signalling would be acquired by an active decrease in entropy (followed by some sort of "passive" restoration). Is there any reason why that is not so? Are there other examples of signalling where that is the other way round?

Or am I just lacking understanding and messing up definitions?

Thanks for your help


texts: How can I re-format my DNA motifs' position weight matrices?

texts:
I am working with a set of DNA motifs that are predicted as potential regulatory motifs (e.g. transcription factor binding sites).
The motifs belong to several species, and I wanted to cluster these motifs via their Position Weight Matrices (PWMs) (also known as PSSMs) to collapse similar motifs together into groups.

There is a tool called MATLIGN (website here) that does what I need, but their required format for the PWMs are different to what I have, they claim:

  "Matrices must be in the frequency matrix format (only integer numbers
  are acceptable)"

The problem is that my PWM matrices do not have integer numbers but decimals instead. e.g.:

     A        C        G        T
1    0.000000 1.000000 0.000000 0.000000
2    1.000000 0.000000 0.000000 0.000000
3    0.000000 0.000000 1.000000 0.000000
4    0.000000 0.421755 0.000000 0.578245
5    0.289407 0.000000 0.282556 0.428038

In other words, instead of the decimal values I have in my matrix I need to have integer counts. Could anybody suggest what I can do? Would I need to create artificial "pseudo-counts"?


texts: In Western blot, is Ponceau S a valid loading control if band intensities vary between lanes?

texts:
I have done a Western blot and I am using Ponceau as a loading control to normalise my measurements against a protein of interest. For my Western blot I have a number of wild-type and knockout samples which are in pairs. I have loaded my samples onto the gel pairwise in the following arrangement: WT/KO/WT/KO/WT/KO/WT/KO. In total, I have four pairs.
In my Ponceau-stained membrane image, in some of the pairs, the band for the knockout sample is visibly  fainter than the wild-type band. I have read that loading controls are used to ensure that variations in protein abundance between experimental conditions are due to actual biological variations and not due to inconsistencies in amount of protein loaded onto the gel.
I was wondering, if there are some bands that are fainter in some of my pairs, would using Ponceau as a loading control still be valid? Any insights are appreciated.


texts: Where in the digestive tract are melatonin pills dissolved? Same question for gelatin capsules

texts:
I want to do a blind controlled experiment on myself to learn whether melatonin pills have any effects on me. I bought some empty gelatin capsules. I am going to fill some of them with rice and put pieces of melatonin pill in others.

Melatonin pills instruction says I should take it 30-40 minutes before going to bed. Now I wonder if the timing is the same when stuck inside gelatin capsules. Also is it possible that melatonin pills stuck inside capsules will get to a later stage of the digestive tract than they should and thus will not work.


texts: Why is membrane potential not zero at equilibrium?

texts:
For the squid giant axon, the membrane potential computed by the Goldman equation is -60mV. And the Nernst potentials are (the differences between the K+ and the Na+'s Nernst potential and the membrane potential let the mechanism work):

  K+ = -74mV
  Na+ = 55mV
  Cl- = -60mV

I am wondering if the membrane potential is 0mV, whether the K+ and Na+ Nernst potentials still cause the mechanism to work, so can 0mV be a reasonable value? (That is, I think the value of potential is not important at all as long as the mechanism works well, is this true?)


texts: Are there chromosomes that we inherit that are not recombinated?

texts: We do have chromosomes that recombinated ,but aren't there pure chromosomes that are not recombinated that people would have?


texts: A good book for history of biology/biotechnology for lay people

texts:
I have many friends who are interested in Biology and want to know more about the subject in general (like a history of biology, from Darwin's theory, to DNA structure discovery, to the human genome project). Of course, I cannot suggest to them to read Alberts or Lenninger. Do you know whether such a book exist? I guess that a book that covers most fields of biology cannot be compiled, but even more focused book would do.

Let me try to narrow it down: something like the greatest discoveries in the field of biology (like this article) would be an interesting book to read.

I am not sure how appropriate this question is for SE, but I am sure that I will get the best answer here. Besides, it would be great if lay people can be more excited about biology and contribute to the site growth.


texts: Difference between the spinal cord and vertebrae column

texts: What is the difference between the spinal cord and the vertebrae column, they both run through from the head to the abdomen. Does any one have any idea.


texts:
Following quote is from this wikipedia page on single unit recording.

Intracellular single unit recordings require electrodes be inserted through the cell membrane to record from within the cell. Glass micropipettes or metal electrodes may be used for intracellular single unit recordings, but glass micropipettes are preferred because their high input resistance allows more precise recordings for measurement of resting potentials.

How high input resistance helps better recordings? Shouldn't recording electrode have as low resistance as possible?


texts:
I just wanted to get a realistic viewpoint of our nervous system. I understand arteries and veins, but I wanted to know how similar our nervous system is to that?

I understand we have neurons (please correct me if I am wrong) all over the surface of body. Whenever we feel a touch a neuron fires a response, and that response travels through axons (myelin sheath).

My main question is what a nerve exactly is. Is it a long axon? How many axons (same thing as neuron body?) are in a nerve? I am sure it depends on different nerves.


texts: What’s the term used to define a terrestrial being that moves by using six limbs?

texts:
I know that Bipedal locomotion would describe how beings like humans and ostriches get around.

Quadrupedal locomotion describes how beings like dogs and cats move around.

What about insects, specifically, a cockroach? I believe a cockroach has six “legs”, what would be the term used to describe that type of locomotion?


texts:
I would love help outlining a basic walkthrough of the wet-lab techniques for processing blood samples from patients, all the way to loading a BeadChip, to the part just before Next Generation Sequencing takes place. Here is my basic understanding so far, that I am not 100% certain is accurate. I am not a biologist - I just communicate with them, so I do not need any confusing assay names/specifications that are important only for wet lab biologists.

Steps:
1. Collect blood from patient.
2. Purify DNA by isolating DNA
            (Procedure (?): lyse/sonicate, bind using ethanol, centrifuge,
            wash with buffer, centrifuge again, rinse with water, centrifuge
            again)
3. Cut DNA into 100-150 bp read fragments
            (Procedure (?): with restriction enzymes? how do you determine
            read length with restriction enzymes?)
4. Separate double stranded reads into single stranded reads
            (Procedure (?): denature with heat)
5. Amplify reads via PCR, leaving you with many single stranded reads
6. Disperse sample evenly into all cells on a BeadChip. The BeadChip
      contains bountiful DNA polymerase and fluorescently tagged single nucleotides.
7. Submit the BeadChip to the Next Generation Sequencer for processing.
8. You end up with a BUNCH of images which you can transcribe into sequences
      based on the color illuminated in each photo capture, in each position
      on the BeadChip.

Here's what doesn't make sense to me:
Step 6. You either have to only put one PCR read product in each cell at a time - which would take FOREVER, if you wanted to sequence someone's whole genome... Or you have more than one light going off per cell, per BeadChip, in each photo. If the latter is the case (which it would have to be for high throughput wet lab experiments), how do you determine between photo captures of a given cell in a BeadChip that the nucleotide going off in photo 2 is a part of fragment n or n+k?

Does this make sense? Basically, how are BeadChips loaded with sample reads for NGS genotyping? I know that reads are "anchored", but are they anchored in each cell of the BeadChip? This is the only way this makes sense to me.

Thanks for any insights!


texts:
During snorkelling a couple of months ago on Canary Islands I've been watching stingrays which I think are "Roughtail stingrays". Often this fish (on pic) was accompanying those stingrays. So what kind of fish is this and why it's hanging around stingrays?

Stingray:

I've seen this behaviour many times so I'm sure it's not a coincidence.