texts: Which fish will have more developed gills?

texts: A fish lives at the depth of 1000-2000m and another at the depth of 200-700m. Which of them would have a more developed gill system ?


texts: Does a walk after a meal help with digestion?

texts:
I am a bit confused with the notion that "walking after meals helps you in digestion ",

Some say that it helps, whereas others oppose it. Can someone come up with a valid explanation for this?


texts: What are some examples of scaling laws in biology?

texts: I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?


texts: How does the brain alter/inhibit muscle reflexes?

texts:
I can find lots of information on how stretch-reflexes/reciprocal-inhibition/autogenic-inhibition work but from them all it's unclear how exactly the brain interfaces/controls/disables such automatic muscle reflexes when it needs to?

Can it alter the weighting of inhibition in antagonistic muscles?  As well as 'set the length' for a stretch reflex to target?  Or does it somehow control both 'with one value'.  Where and how exactly does it interject into the feedback loops?

I am trying to understand it more from a programmers pseudocode or equation point of view rather then get lost in meandering biological terms I have seen everywhere that gloss over this point.


texts: To diagnose osteomyelitis of vertebral column in chronic kidney failure

texts:
Assume you suspect amyloidosis because of the history of the patient: problem with vertebral column and "purulent" (serous, fibrous, or hemorrhagic) inflammation when patient very young.
Now, the patient has a chronic renal failure.

Is there any other method to diagnose the fracture of some bone than röntgen?
Assume you do not know where the fracture is exactly.


texts: Downloadable worldwide database of disease statistics?

texts:
I am looking for a downloadable database of disease statistics. I have emailed the good folks over at HealthMap, but they haven't gotten back to me yet.

As far as I can tell, their data relevant to my project is gathered from the World Health Organisation, ProMED Mail, GeoSentinel, Google News, Moreover, Baidu and SOSO.

I can scrape the data from each of these sites and aggregate it in the same way HealthMap has, but that is a large project in and of itself, and I only have a couple of months for this not-for-profit project.

Do you know of a downloadable worldwide database of disease statistics?


texts: If number of children born were spread more evenly among all parents, would our species' genetics have more variability?

texts: Instead of some parents having lots of kids, if the number of kids were spread more evenly to parents having few kids and people who have no children, would it introduce more genetic variability in our species in general?


texts: Absorption of digested food in small intestine

texts:
My book says

  glucose , galactose and amino acids are transported into cells of villi via secondary active transport(sat). Fructose is transported by facilitated diffusion(FD) .short chain fatty acids , vitamins diffuse into cells of villi. From there all these are transported to blood by FD.

This site says the reason for using SAT: http://www.phschool.com/science/biology_place/biocoach/biomembrane1/glucose.html

But I want to know why fructose, vitamins and short chain fatty acids do not need S.A.T. and travel via FD (or just diffusion)?dont they get reabsorbed into small intestine ?


texts: Where can I find a list of common enzyme cofactors and/or co-enzymes?

texts:
Where can I find a list of enzyme cofactors and/or co-enzymes, ordered by how common they are?

For example, $O_2$, $H_2O$, $ATP$, $ADP$, $NAD$, should be ranked in the first places, because they participate in most reactions.


texts: What is the difference between sieve cells and sieve-tube elements?

texts: I looked it up and I'm still confused. Apparently, sieve cells lack sieve plates? What does that really mean? It's difficult to find a good picture of either.


texts:
A circular plasmid of 10,000 base pairs (bp) is digested with two restriction enzymes, A and B.  This produces a 3000 bp and a 2000 bp bands when visualized on an agarose gel. When digested with one enzyme at a time, only one band is visible at 5000 bp.

If the first site for enzyme A (A1) is present at the 100th base, the order in which the remaining sites (A2, B1 and B2) are present is -

(A) 3100, 5100, 8100

(B) 8100, 3100, 5100

(C) 5100, 3100, 8100

(D) 8100, 5100,. 3100

NOTE: This is a Kishore Vaigyanik Protsahan Yojana 2014 exam (stream SX) Question. I really couldn't understand the diagram shown in the solution, and my teachers were of no help either. The diagram in the solution is:


texts: CD47 aka the "don't eat me" signal has recently been claimed to be expressed on all tumor cells. This doesn't seem to corroborate with other cell-biology experiments. On what other cells is CD47 expressed?


texts: Lobed Nuclei still count as One nucleus?

texts: Do the Lobed Nuclei of immune cells (such as Megakaryocytes) still count as one nucleus?


texts:
I'm trying to figure out if it's possible to have a stress response without being initially, or simultaneously aroused. I'm defining stress to be physiological stress (ie. release of cortisol) and arousal to be activation of the sympathetic nervous system.

Every example I can think of, these two are not independent. In the case of "fight-or-flight," one initially activates the sympathetic nervous system, which is then followed by the release of cortisol. Or in individuals with major depressive disorder, their sympathetic nervous systems are constantly activated while cortisol is being secreted.

So, is it possible to experience cortisol release without activation of the sympathetic nervous system?


texts:
Can the calcification response of a marine organisms, at different pH conditions, be assessed by the calcium magnesium ratio?
the calcium magnesium ratio is a proxy  of calcification?


texts: How does Ultra-pasteurized milk compare with pasteurized milk?

texts:
I am specifically interested in whether all proteins and nutrients lose their structure permanently because of the very high temperature of ultra-pasteurization.
What is the case for pasteurized milk?


texts: What are some effective strategies for testing whether a trait is an adaptation?

texts: Although signs of evolution are to be found everywhere across taxa, it sometimes seems difficult to discern whether a trait is a retained accident or an adaptation. It also seems like there is a temptation in people to come up with just-so stories to explain traits as adaptations. What is an effective strategy for coming up with tests to determine whether a trait is an adaptation or not?


texts: Does the anatomy of our hand result in (computer) mouse-accuracy that varies by direction of movement?

texts:
First off, I apologize if this isn't the right stackexchange sub-site for asking thsi question.  I was torn as to where I should post this question: it could plausibly belong in Biology, User Experience or even Arqade.  However, given the root of my question has to do with the "wiring" of the human hand, I elected to post it here.

My hypothesis/question:
Let's assume that wrist adduction/abduction is responsible for horizontal movement of the mouse cursor and that finger extension/flexion is responsible for vertical movement of the mouse cursor.  (I am, of course, willing to revisit this assumption, if necessary.)  Would it be accurate to say that we are "hard-wired" to be capable of higher precision in vertical movement of the mouse cursor than in horizontal movement?

Description of mouse grip:
In making the above assumptions, I assume a fingertip-grip style of the mouse (as opposed to the claw and palm grips). The (corner of the) wrist rests on the table and acts as a pivot for allowing side-to-side motion (i.e., horizontal motion of the mouse cursor).  Meanwhile, flexing/extending the fingers allows for pulling/pushing the mouse away from us, (i.e., vertical motion of the cursor).  The main (admittedly unscientific) reason behind my hypothesis is that vertical movement of the mouse cursor uses similar finger motions as those used for hand-writing (which is, after all, a highly precise activity).

(I understand that my question makes the assumption that we are capable of more precise movement with certain muscles of our body than we are with others - please let me know if that's a flawed assumption.)

Why do I care about this?:
If my hypothesis is correct, there would be implications on mouse settings (namely, horizontal and vertical DPI*) that are conducive to both high accuracy and speed.  The key issue is that if we keep our wrist in place (i.e., no sliding/lifting of our pivot point) - then we're able to move the mouse a greater distance side-to-side (i.e., horizontal motion of cursor) than we're able to move it toward/away from us (i.e., vertical motion of cursor).  However, if there is evidence to support my hypothesis, than an appropriate adjustment (which wouldn't result in a loss of accuracy) would be to have a slightly higher vertical DPI than horizontal DPI.

*DPI = dots (i.e., pixels per inch).  For example, I have a resolution of 1366x768 (which is in units of dots or pixels) and a 600 dpi mouse, which means that my (physical) mouse needs to be moved ~2.3 inches (1366 divided by 600) in order for the mouse cursor to move the full horizontal distance of my monitor.  To put it simply, lower DPI results in higher accuracy but it is preferable for our wrist to remain in-place in the interest of speed.


texts:
My favorite color pigeon is Ash-Red, but I don't see a lot of them.  I figured it must be a recessive phenotype, but when I googled it, I found out it's dominant.  So why aren't there more Ash-Red pigeons around?

Edit: I'm in North America.

Edit 2: This website from the University of Utah is where I learned that Ash-Red is the dominant phenotype.


texts: Hardy Weinberg Equilibrium after 5 Generations

texts:
1
There is a population not at HWE where red eye = $a^+$ (dominant) and white eyes = $a^-$.
If:
$a^+/a^+ = 0.6$
$a^-/a^+ = 0.1$
$a^-/a^- = 0.3$
what are the frequencies of the $a^+$ and $a^-$ alleles?
My attempt: So if it's not at HWE then I should divide the heterozygotes equally to get $a^+ = 0.65$ and $a^- = 0.35$.
2
We are now at HWE.  What are the frequencies in the next generation?
My attempt: so if $a^+ (p) = 0.65$ and $a^- (q) = 0.35$ then $p^2 = 0.42$ and $q^2 = 0.12$.  Then using $p^2 + 2pq + q^2 = 1$, I can figure out that the heterozygotes make up $0.46$.  So the frequency of the $a^+$ allele is $0.42 + 0.46 = 0.88$, and then $a^-$ should be $0.12$ (because they should add to 1)
3
What is the frequency 5 generations later in HWE?
My attempt:  Wouldn't it be the same answer as #2. I'm not sure how more generations in HWE would change the allele frequencies.


texts: The oldest common ancesstor of all human beings

texts:
Do all human beings have a single oldest ancestor (a man and a woman), or were there were many ancestors at the same time at different places on earth?
This article sheds some light. Is there another authoritative report released more recently?


texts: Are we evolving as fast as the oxygen is depleting?

texts: How much oxygen saturation have we lost in the last 100 years? As oxygen levels dwindle and industry, deforestation,  and population increases, at what year and saturation will the low levels of oxygen become a problem in human development? Would living or sleeping with higher levels of oxygen increase cognitive or physical ability?


texts: Why does allele linkage cause disproportionate phenotypic ratios?

texts:
I was learning about allele linkage in Biology class and I got confused by the resultant phenotypic ratios.

Say you have a dihybrid cross BbGg x BbGg.

The Punnett square would look like the following (sorry for bad formatting):

     BG...... | Bg.... |  bG.... |  bg

BG   BBGG       BBGg      BbGG      BbGg
---  -----------------------------------
Bg   BBGg       BBgg      BbGg      Bbgg
---  -----------------------------------
bG   BbGG       BbGg      bbGG      bbGg
---  -----------------------------------
bg   BbGg       Bbgg      bbGg      bbgg

So:

This would result in a a 9:3:3:1 phenotypic ratio. (Dom/Dom : Dom/Rec : Rec/Dom : Rec/Rec)

However, if the alleles B/b and G/g were on the same chromosome, the ratios turned out to be around 4:1:1:4 in an example (still Dom/Dom : Dom/Rec : Rec/Dom : Rec/Rec)

The stated reason was that there would only be Dom/Dom and Rec/Rec, and the Dom/Rec and Rec/Dom only showed up due to crossing over. However, this begs the question: Why could Dom/Rec and Rec/Dom not have occurred prior to recombination? My reasoning is that just because the alleles are on the same chromosome does not mean that they must both the autosomal chromosomes for the allele must have either a dominant genotype or recesssive phenotype. That is, before crossover, there should still be a 9:3:3:1 random distribution between phenotypes represented by genotype sets (BbGg/BBGg/BbGG/BBGG):(Bbgg/BBgg):(bbGg/bbGG):(bbgg).

Note: when I say dom/rec for example, I mean that for the first allele the character represented by BB or Bb was expressed, and the "rec" means that for the second allele the character represented by gg was expressed. I am assuming autosomal dominance for simplicity.

If anything is unclear, don't hesitate to comment. I'm pretty tapped out right now. Thanks, hob


texts: When is really necessary to visit field to observe sample collection process?

texts:
I know this could be a bit generic question, but for the sake of providing context this applies to a Transcriptomics Thesis.

Yesterday I've seen two researchers discussing about if it was really necessary for a post-doc geneticist to visit the place where the blood, weight, height, hair (and other) samples are taken.

From your experience, it is really necessary for a post-doc to travel and visit the field? Does that add real value to a Thesis? Shouldn't the sample collectors report everything like their name, how they measured a sample, etc?


texts:
What is meant by "pro-acinar cell" in the following sentence? progenitors/precursors?

A transient decline in Neurog3 expression from E11 to E12 coincides with peak segregation of MPCs into proximal, Ptf1aNkx6-1+ bipotent progenitors (BPs) and distal, Ptf1a+Nkx6-1 pro-acinar cells (PACs).

Thanks


texts: DIY extraction and long term storage of human DNA sample?

texts:
What is the recommended DIY way of extracting and long term storing of human DNA samples to store at home and send for sequencing in years time? Considerations:

Sample material: cheek swab, hair, blood?
Extraction: which detergent, alcohol?
Storage: freezer? what temperature?

Any ideas?


texts:
I'm working on a project about detecting SNP association with a disease. As I understand, SNP is a single variation of the nucleotide that occurs for more than 1% of the population. However, I couldn't connect this idea with the dataset in hand. The rows in my dataset represent each patient and the columns contain SNP information. For example:

ID  exm355 exm615
1     T_T   A_C
2     T_T   C_C
3     A_T   C_C

I have no idea why the SNP columns contain 2 nucleotides(T_T, A_T, A_C, C_C). As the definition of SNP, I thought it should show only the variant nucleotide or am I misunderstanding anything? How could I interpret T_T or C_C and how could I know which nucleotide is the variation from the common ones in the population?

Thanks all


texts: What is the carbohydrate found in almonds, cashews, pecans, hazlenuts and pistachios?

texts: So for a school assignment I need to figure out which carbohydrates those nuts have. I first though they probably have starch but I am not sure. Can someone verify this for me, and/or send a link where I could find this information? Thanks.


texts: Recovering Coma patient with theoretical full knowledge of heart function

texts:
In coma, there is the medullary depression (stage of agony).
Spontaneous respiration and circulation cease i.e. vasomotor center.
There is no full circulatory and respiratory support.

Assume you could stimulate and coordinate fully the autonomic nervous system of the heart.
You know exactly which pacemaker cells and pathways are blocked in the particular coma patient.
I have in mind Schumacher's case - where you have head injury.
I think you should consider, in his case, the pressure of the head also if you can restore circulation and respiration artificially.

Some neurologists say that it is practically very difficult to wake a person if he has been in coma for six months.
I would like to understand this.
I think it is because of atrophy of muscles and probably something with atherosclerotic changes.
However, I am still interested in your opinion about the theoretical situation - if you can restore heart and respiration centre, can the recovery start?

What are the limitations of restoring the function of the body by restoring the circulation and respiration i.e. vasomotor centers after long stay in coma?


texts: Is there a reproductive barrier between Khoisan and other humans?

texts: I have heard in an ethnology lecture that more or less all human ethnicities interbreed without a barrier (rate of reproduction of fertile offspring) except the Khoisan + any other human ethnicities, where fertile offspring is less likely than when other humans interbreed (as a an anecdotic side note, there are rumors about Zulu men who prefer Khoisan women as second or third spouse in order not to produce too many kids). My question is if some can confirm or falsify this (any literature coverage)?


texts: Is the basic reproduction number unique?

texts:
Given any epidemic model of an infectious disease, there are various ways of computing a basic reproduction number($R_0$) such as;  the next-generation method, survival function, largest eigenvalue of the Jacobian matrix and so on.

My question is,

  Do we get the same $R_0$ for the same model but using different methods of computing $R_0$?

If we don't(if $R_0$  is unique) what is the explanation?
Are we allowed to use "this" different $R_0$ in writing a paper?


texts: What is this whitish jelly-like substance on a branch?

texts: I came across this whitish jelly-like substance hanging on a fallen branch. I assume it was growing there and I feel like it might be a fungus or algae of some sort, or maybe an egg sack. I was hiking in a mountain rainforest in Hawaii. The area I found it was shady with adequate indirect sunlight, about 65-70°F at the time. There weren't any others nearby and it was the only one like it that I happened upon during the hike. What is this and if it is living, how does it grow, how does it live?


texts: 10.5 ounces, found laying on ground, central California coast.


texts: Can Pichia pastoris (species of yeast used for recombinant protein) produce the non-protein amino acid Ornithine? Or does it express ornithine at all?


texts: Is an Eidetic Memory (or other unusual forms of memory) less susceptible to anterograde amnesia?

texts:
I'm a physicist, so as a fellow scientist I want to apologize because this question will be entirely based on anecdotal inferences and I am well aware how irritating that can be.

I have an eidetic memory and I've never experienced any of the common forms of anterograde amnesia. No blackouts from rapid consumption of alcohol (and believe me, I've tried. That was the fun part. But not for kids; then it's not fun), not from extreme fatigue, head trauma, I even went in for surgery once and the anesthetist said at one point "Well since you asked, the amnesiac should be setting in right about now" and I vividly recall another couple minutes of conversation while we waited for the general anesthetic to knock me out.

So, naturally, I just assumed it must have been because of my eidetic memory. But I've always had an interest in neuroscience and now my curiosity has gotten the better of me. Surely the memory systems of all people are similar enough that amnesiacs and the like should work on everyone. So I ask, are eidetic memories (or perfect, or photographic, or other unusual forms) actually less susceptible to anterograde amnesia? Or perhaps have I just been the victim of probability; this is more a matter of luck not neuroscience?

Please don't spare the gory details, neuroscience is cool (Neuroscientists are brainy guys. Sorry, I couldn't resist that pun). That said, I am physics, not biology; I'm probably under-specifying the question. Let me know if it's too broad and I'll try to focus.


texts: layman inquiry into mechanics of evolution

texts:
Consider a species. Without some particular mutation, its members have quality A. Suppose that quality B is better for the survival of any individual member of the species. If one member possesses quality B, natural selection could take over.

What if B is preferable to A, but the intermediary stages are not preferable to either A or B? Can a species go from A to B?

Say an organism has 4 legs but having 6 would be advantageous. Could it get to 6 without some disadvantaged intermediate forms? Or is there a way for a single genetic mutation to result in a one step change? Also, if no organism has ever made such a transition then I suppose it can go without explanation. But then maybe something went from 6 legs to 4, or something.

I hope this isn't too rambling. Kindly,


texts: Will fruit/seed of a bonsai yield another bonsai plant/tree?

texts:
With practice one can create a bonsai; no complicated modification of the DNA in a high-end lab required. The bonsai will even beget bonsai fruit.

What I am curious about is - if such bonsai fruit is planted again, will it give rise to a normal, or a bonsai tree?


texts:
What species is this jumping insect?

Found in the United Kingdom in summer.

About 1 cm body length + 1 cm feelers.


texts: Why does the intensity of an action potential once generated at the trigger zone remain undistured throught the axon?

texts:
What causes this consistency?
I read the previously asked questions on this site none of them carry an answer to this question.


texts: Are any organisms known to use meiosis I to create non-identical offspring asexually?

texts: So, there are numerous species of animals who use parthenogenesis, but to my knowledge the reproduction is clonal. That is, the offspring are identical to the mother. Are there any documented cases where a female goes through meiosis one to produce varied cells that are now diploid and these cells do not go through meiosis two, but rather develop in to a diploid organism? It would seem an effective reproductive strategy in that it generates genetic variation without a mate (at least more-so than strict asexual reproduction). Is my logic flawed in some way?


texts: What is the mechanism of aspirin as an anticoagulant?

texts:
I understand that aspirin prevents blood clots from forming by interfering with the clotting action. I want to know at which stage aspirin interferes with clot forming and what really happens in the process. I've used google to understand this but did not find a satisfactory answer.
For example, here I found:

How can aspirin prevent a heart attack?
Aspirin interferes with your blood's clotting action. When you bleed, your blood's clotting cells, called platelets, build up at the site of your wound. The platelets help form a plug that seals the opening in your blood vessel to stop bleeding.

But this clotting can also happen within the vessels that supply your heart with blood. If your blood vessels are already narrowed from atherosclerosis — the buildup of fatty deposits in your arteries — a fatty deposit in your vessel lining can burst.

Then, a blood clot can quickly form and block the artery. This prevents blood flow to the heart and causes a heart attack. Aspirin therapy reduces the clumping action of platelets — possibly preventing a heart attack.

Every site I visited had descriptions like this (mostly concentrated on the medicinal side). I want to know what aspirin does that prevents blood clotting at the chemical level, which I haven't been able to find.


texts: Why doesn't ovulation occur in both ovaries simultaneously?

texts:
I know that in human body ovulation takes place at only 1 ovary every month. But development of a follicle depends on FSH levels in the blood, and since both the ovaries are exposed to the same blood supply, how does it make sense for development of follicle to be seen only in one ovary? Aren't both ovaries exposed to same FSH levels every month?

I am not able to figure out the solution to this anomaly and would appreciate some answers.


texts: How many transmissions does it normally take for a neuron to reach threshold for action potential?

texts:
This video illustrates and explains how the dendrite connections being activated causes the neuron to be polarized until it reaches "threshold", and firing. My question is how many times might a neuron's dendrites need to receive "fires" from other neurons in order to reach threshold. I think I understand that it isn't a binary matter, so I realize the answer isn't going to be 5 or 5,000 but a general range.

As a related question, how long does it take for polarization to wear off if additional transmissions don't come in, and if the polarization does wear off, is this wear-off mechanic important to the neural system? Is wearing off a significant aspect of the neural process, in other words?


texts: Are there humans which the brain sends signals to the limbs faster than the average?

texts: I have done some researches on the time taken by the brain to send signals, but I didn't find whether that time is the same amongst all humans or there are some differences, and I have based my question on an article which mentioned that Messi(one of the best players in soccer history)'s brain send signals to the limbs faster than the normal human (https://www.ncbi.nlm.nih.gov/pubmed/27010676), so is this possible to happen.


texts:
I would like to use MultiPipMaker for testing a genome alignment between two sequences, each sequence is in .fasta format, but the problem is that when I submit the couples of file that I need, the web browser sends an email that the blastz has timed out. Does anybody know why is the that?

The address of the program is:

http://pipmaker.bx.psu.edu/cgi-bin/multipipmaker

thanks


texts: Tc and Th1 interaction and viral immune response

texts:
Tc is T cell which can give T killer cells and T helper cells.
T helper cells (Th1) see the pathogen presented by antigen presenting cells (dendritic cells and macrophages).
They then secrete antigens to kill the pathogen.
If there is memory from previous interaction, then it will be easier to protect.
However, since some viruses replicate fast (RNA particularly), this memory benefit is often lost, like in the case of influenza virus A and B types.
However, I am uncertain how to explain this immunology with viruses.

How can you explain this general viral interaction better in the immune response?

I have these pictures in mind:

and


texts: Are there any known microbes capable of living in almost pure carbon dioxide?

texts: Some bioengineering is investigated in high carbon dioxide environments. Are there any microbes like bacteria or Archaea capable of living and multiplying in such environments?


texts: How does a stonefish get oxygen out of water?

texts: It is said that the stonefish (Synanceia) is able to stay out of the water for up to 24 hours. I wonder how they get oxygen from the air. Could someone explain this?


texts: Location of embryo development in angiosperms

texts: What floral organ does the development of the embryos of angiosperms occurs in? Is it the ovary? The pollen tube grows down through the style and double fertilization occurs and the embryo begins to develop in the megasporangium.


texts: Found on ground by house in residential neighborhood in Fort Pierce FL. looks mature maybe 17".


texts: What is the difference between sequence, reads, and contigs of genetic material?

texts:
Can someone explain the differences between sequence, reads, and contigs of genetic material such as DNA, if possible with an example?

I am new to bioinformatics, and I have not found any conclusive answers for all these concepts on the web.


texts: Can anyone identify this insect from India?

texts: Found this bug in Chennai. Curious to know what kind it is. Does it pose any danger?


texts:
I stumbled upon a few hundred of these swarming around two different places in my living room today. They kind of look like a carpenter ant to me, but I'm not sure.

Also, I'd love to know how you identified the ant.

// EDIT, per a helpful suggestion, I'm in Los Angeles, CA, US. We just had rain come through within the last 4-5 days and it has since dried up.


texts: Where do migratory birds go when it rains?

texts:
I was reading a comic from XKCD which inspired me to ask this question: "well, where do they go when it rains?" I know that when it rains you usually don't see any birds flying through the sky.

I imagine they normally hide in trees or under other kinds of cover. But for migratory birds, I don't think it is possible to hiding under cover until the rain passes. There might not be any cover (trekking across seas) or it might stay rainy for a very long time (and therefore cold...).

I did some research, but the answers are conflicting. Some people say they do stay in trees, others say they AVOID trees (because trees can snap in a storm, plus if there's lightning then sitting in a tree will net fried birds). Then there's people saying that birds have a waterproof coating... but that's a bit contradictory with me not seeing birds when it rains.

So where do birds go when it rains?

I assume that different bird species and groups of birds will behave in different ways. I am interested in the case of migratory birds because they are likely to encounter different climates and have perhaps devised strategies to be safe. I would appreciate any well-referenced examples.


texts: Names of nerves in hands, shins and face

texts:
I am looking for the names of the nerves in 3 specific locations of the human body:

The nerve running along the "top" (opposite side of the palm) portion of the thumb, from knuckle to fingernail (see 1st picture below); and
The nerve running along the anterior tibia (also see 1st picture below); and
The nerve(s) of the face running along the eyebrows and outer edges of the eye sockets (see 2nd picture below)

After looking here, here and here, the best I could muster was:

The median nerve is the nerve that carries sensory signals from the top of my thumb; and
The superficial peroneal nerve is the nerve that carries sensory signals from my anterior tibia

But in every diagram of the face's nerves, there are simply too many for the article/blog/diagram to enumerate, and I can't discern which specific nerve or nerves runs outside of the eyes and across the brows.

Any ideas? Here are the pics to solidify the specific areas I'm looking for:

Please note: this is not homework! And although it may be considered by some to be a rudimentary question, I have actively tried to research this myself and have come up short. Below, I explain all the failed methods I attempted to figure this out on my own. So all this to say: if you do down/closevote this, please don't do it because you think it's homework or because you think it shows a lack of research!


texts: Why does breathing increase in higher temperatures?

texts: In my experiment, my group increased the temperature of a fish's water. We noticed the fish took more breaths than the prior normal temperature. Is this because the fish is trying to breathe in the water's oxygen, which is evaporating more quickly than in normal temperature?


texts: What types of mathematics are useful for studying genetics? Of course, statistics is, and I'm guessing set theory and group theory, but anything else? What about ordinary and partial differential equations?


texts:
I am wondering if anyone has seen a data of Giardiasis (Giardia Lamblia) cases  in different countries on the world? I have found for different diseases and also for 'diarrhoea diseases' in general, but I need especially for Giardia Lamblia.

Any suggestion where I can try to look for this data will be useful.

Thank you very much!


texts: Why do humans lose subcutaneous fat tissue with age?

texts:
Why exactly do humans lose subcutaneous fat tissue with age?
It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age.

One hypothesis is that as the vascular system weakens with age, the fat cells on the perimeter of the body shrink and die because they don't have enough blood flow to sustain them.  The problem with this hypothesis is that subcutaneous fat loss is very gradual and starts during young adulthood and continues. It also happens in very fit individuals too.

Another hypothesis I read before was that subcutaneous fat is loss because of a drop in estrogen levels after menopause.  This hypothesis doesn't explain why men lose subcutaneous fat with age.  Also, women start to lose fat on their hands and upper cheeks long before menopause starts.


texts: Efficient algorithm to calculate various population divergence statistics

texts:
Intro and description of the data

I am simulating the evolution of very long DNA sequences. The model works well, is performant and will output data in the following kind of fasta format

>it0pop0ind0locus0
ATGTTG...
>it0pop0ind1locus0
ATGTTG...
>it0pop0ind2locus0
ATGTTG...
>it0pop0ind3locus0

, where it stands for iteration (replicate of the same simulation), pop stands for population (or subpopulation of the metapopulation if you prefer), ind stands for the individual chromosome that was sampled, locus stands for locus which is defined as a very big sequence (0.1GB or 1 GB maybe).

Issues

I never had to analyze genetic data (or only during my Bachelor degree). As I know nothing about the available algorithms that exist to make this kind of analysis, I first thought I would just make my own code (in Python). It turns out that I might have a lot of data to analyse and my Python code will be way too slow. I may also experience RAM-related issues

Moreover, I want to measure a whole series of different statistics of population divergence (Fst for each site, Fst averaged over many sites following Cochramm and Weir, Gsd, absolute number of fixed sites that differ, etc..), so the algorithm would need to be quite flexible.

Question

There are a bunch of existing efficient algorithms that would eventually fit my needs. Can you please give me some recommendations and make a few comparisons of what's available out there?

An efficient algorithm that takes in input:

a description of the naming convention in the fasta file, or a list of positions for each locus and each population in the fasta file.
A description of how I want the statistics to be calculated

and that outputs those statistics. That'd be great!


texts: Creativity, innovation and ideation. Is there something in the brain that makes the brain think that way, as opposed to "normal baseline". What triggers creative thought in humans?


texts:
What is the rate of occurrences of Down syndrome in subsaharan African populations? Is it the same as in white European populations?
An interesting hypothesis came to my mind:
Could it be that Down syndrome is the result of interaction of different dominant or recessive Neanderthal or Denisovan genes that European and Asian populations cary in small percentages?


texts: What is the importance of hydrogen bonds in water? and other questions:

texts:
These are extremely simple questions — basic biology — but I would like to make sure that the way I have answered is at the very least correct.

Hydrogen bonds are very weak, so how is it possible that they are so important in the properties of water? Hydrogen bonds in water provide many characteristic benefits to water: cohesion (holding water molecules together), high specific heat (absorbing heat when breaking, releasing heat when forming; minimizing temperature change), high heat of vaporization (several hydrogen bonds must be broken in order to evaporate water), lower density of ice (molecules in ice are spaced farther apart), and solubility (polar molecules are attracted to ions and polar compounds, making them soluble in water).
Why do we feel cooler immediately after we go swimming than we do after we have fully dried off? We feel cooler immediately after we go swimming than we do after we have dried off because it takes a lot of heat to evaporate water; however, once we dry off we remove much of the water from our skin, and the water is evaporated much more quickly.
If water were non-polar, would our temperature heat up less quickly or more quickly if we went outside on a hot day? Why? More quickly. Because hydrogen bonds within water slow down the movement of molecules and allow for water to have a very high specific heat.


texts:
I've read a lot on both sides of the debate of low carb vs low fat diets trying to make some sense of what is being proposed. The lipid hypothesis runs roughly along the lines that we have lots of observational epidemiological evidence that eating a high fat diet correlates heart disease/obesity/enter disease of choice.

An alternative hypothesis is that high carbohydrate diets cause these things. Since the studies haven't been done, there is not the correlation to point to. This hypothesis is believable (to some people) due to the well-understood biological pathway: Carbohydrates turn to glucose, which causes an insulin release, and insulin regulates fat storage, so high carbohydrate diets lead to weight gain (see a biochemsitry textbook for a more detailed explanation).

My question is: Does the lipid hypothesis have any biological pathway for which there could be proposed a causal relation rather than just a correlation? Of all the speakers/writers on this topic, the low carb advocates always clearly describe the causal relation, whereas the low fat advocates never say why eating fat should cause weight gain.

Note: I'm not interested in discussing the merits of the studies, but rather the proposed causal mechanism.


texts:
As far as I know, humans can distinguish between 5 basic tastes based on various molecules in food and their interactions. There's a level to all 5 so there can be an endless variety of tastes, and we can recognize them with some precision. What surprises me is that we can often distinguish the original flavors in a mix - for example in a salad or even more so in a blended juice. Shouldn't we perceive an entirely new flavor having the average of each basic taste?
Not entirely sure this belongs on a biology forum, but I hope someone can explain :)


texts: Why do eyes feel overwhelmed by light when we wake up?

texts: Many people (I saw a 9gag post 3 days ago and couldn't find it, I'll edit later if I do find it)experience dry/hurting/overwhelmed eyes when they wake up because the light feels too bright. I happen to "suffer" the same. Why this occurs? Is it because the eyes are dry, or because the pupils are contracted, or why else?


texts: Why do some trees have a life span, while some don't?

texts: I have heard that there is no limit on the growth of trees, but then why do some trees, such as boxelders and poplars, tend to live shorter than redwoods, for example? Some advertisements for improved lombardy poplars state that their trees have an extended life span, up to 75 years? The trees with shorter life spans seem to weaken at a certain age, and then contract diseases more easily.


texts:
What type of plant this is and is it poisonous (and, if so, in what quantities)?
The pictures were taken at Gullane Bay, Scotland. The plant is widely present in that region.


texts: Why can't cats run longer distances like dogs?

texts:
Cats can run about nearly 30mph. Their stamina, though, is for short distances. Why can't they run longer?

Can cats be trained to run longer distances like dogs? For instance, could their resistance improve by stair case training (running many times up and down the stairs)?


texts: Why do leukemia and lymphoma cause "night sweats"?

texts:
One of the symptoms of these blood cancers is sleep hyperhidrosis (aka night sweats).  Also referred to as one of the B-symptoms, it may be used for prognosis.

What is the the mechanism behind the symptom?

  Possibilities I came up with:

  Body is more likely to be infected due to immune compromise and thus a bacterial or viral etiology
  White cell counts may be very high causing release of cytokines which affect thermal regulation
  Something else

Why is there more sweating at night and not so much in the daytime?


texts: Who gives a newly discovered microbe its name?

texts: Assuming a hitherto unknown microbe is found - who gives it its name?


texts:
At school, we've been taught that human infants produce rennin/chymosin (which aids in the digestion of milk). More specifically, it is the peptic cells in the stomach which secrete prorennin, the inactive form of rennin (in addition to pepsinogen, the pepsin proenzyme).

User @another'homosapien's answer here also seems to concur with this (excellent answer by the way, I enjoyed reading it).

However

According to Mod. @AliceD's answer here (yet another excellent answer):

  ...in humans there is only a chymosin pseudogene present...

Which (probably?) implies that humans (infant or otherwise) do not produce rennin.

I managed to get my hands on the Textbook of Medical Physiology (Guyton and Hall, South-Asian edition), and according to the book (Chapter Gastric secretions, page 406) peptic cells produce a large quantity of pepsinogen. There is, however, no mention of prorennin. I even flipped over to the Appendix at the back to look up "Rennin", but it turns out there is absolutely no mention of rennin in the book.

My questions,

Some sources claim that rennin is produced in human (infants). Is this true?
Other sources claim that rennin is not produced in humans ( we have a pseudogene for it though). Is this correct (I mean the "rennin-is-not-produced" bit, not the "pseudogene" bit)?
If rennin is produced in humans only during infancy, what stops it from being produced as we mature? (I'm asking this because every source I've seen that claims that rennin is produced in humans, explicitly states that is done so during infancy...which would suggest that rennin is not produced in adults)


texts: Why do earthworms have so little colour?

texts:
Earthworms (or at least the ones that I have seen) tend to be pinkish, but with the front dorsal region being a camoflagued brown. Why is this the case, rather than the entire body or back being pigmented. I couldn't find any reference to the reasons behind earthworm colouration

Here is a picture from the wikipedia page on earthworms, showing the concentrated pigmentation


texts: How to understand relatedness in an infinite island model?

texts:
My understanding is that the relatedness coefficient in kin selection models measures positive assortment. That is, altruism is more likely to evolve if altruists tend to interact with other altruists. As an example, consider a general model of kin selection due to Queller (Queller 1992 "A general model of kin selection"). According to this model, relatedness is viewed as the regression coefficient $\beta_{G'G}$, where $G$ is the individual's frequency of the altruism allele and $G'$ is the average value of $G$ of an individual's neighbors. Queller's definition of relatedness is a measure of positive assortment because, by definition,
$$\beta_{G'G} = \frac{E(G'\mid G) - E(G')}{G - E(G)}$$

If relatedness is positive, if the focal individual is more altruist than average ($G-E(G)>0$), then this individual will tend to interact with individuals that are more altruist than average ($E(G'\mid G) - E(G')>0$).

Now, in Taylor's 1992 kin selection model in patch-structured populations with asexual reproduction ("Altruism in viscous populations"), relatedness $R$ is defined as the recursion (p. 354):
$$ R' = \frac{1}{N} + \frac{N-1}{N}s^2R$$
where $N$ is the number of individuals in each patch and $s$ is the probability the offspring will remain on the natal patch (link to a question about $s$). Here $R$ doesn't seem to be a measure of positive assortment, but simply the chance that two alleles picked at random within the patch will be of the same type.

On one hand, $R$ in standard models of kin selection (e.g., Queller's) measures positive assortment. On the other hand, Taylor's kin selection model for patch-structured populations $R$ does not seem to measure positive assortment within a group but the chance that two random individuals share the same allele.

I tended to think of Queller's model as a general formulation of kin selection (accordingly, Taylor's model would be a particular instance of Queller's model). But, as I tried to explain above, my impression is that Taylor's model is an entirely different way of modeling kin selection ($R$ does not measure positive assortment). Am I missing some connection between Queller's and Taylor's models of kin selection? Or is there any way of connecting the two definitions of relatedness mentioned above?


texts: Do viruses compete with each other or even infect each other? (Virus vs Virus)

texts:
I have read on a few websites that there can be competition between
the viruses in a host for replication, nutrition etc. Do viruses fight against each other, i.e. are there viruses that infect or attack other viruses directly or indirectly?
If yes, can this property help in curing or limiting hazardous viruses such as HIV
using less hazardous viruses which can be cured and can compete with
these hazardous viruses?


texts:
It is well known that UV radiation can damage the DNA and generally harm our skin.
We also know that UV radiation helps on the production of melanin and Vitamin D.

From what I could find, the DNA absorption spectrum goes to almost zero for wavelengths higher than 300 nm. This seems to suggest that we would be safe to use UV radiation between 300 and 340 nm in our skin (as long as the power or exposure is not too high/long to make burns), for therapeutic purposes such as the stimulation of Vitamin D production.

Is this assumption correct? Are there any evidences that we could use this UV wavelength range safely?


texts: If I extract RNA from a (leaf tissue) sample using a one-step phenol:chloroform extraction, how long can those samples be stored at -80°C? And how many times can I defrost and refreeze them before they will become degraded?


texts:
Are the transverse septum in sharks and the diaphragm in mammals homologous structures?

I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim.


texts: I haven't yet found a decent explanation for how water moves throughout plants. It does seem to travel more efficiently upward than out or down. Why is that?  How does it travel through the plant?


texts: Why aren't there any transitional animals today?

texts:
You have probably heard this question before and in different formats. Usually, it is used as a "proof" to disprove the theory of evolution.

I understand that the apes we descended from are not the same apes we see today. However, I can't understand why there aren't any human-ape creatures anymore.
In the world of today, wouldn't an intermediate species (between apes and humans) "win" over both because it has the "feature" of the two.
A creature that can both climb trees and walk on two legs would be more suitable to live in forests than the current forest inhabitants. (apes and humans)


texts: Have cruciferous vegetables been genetically altered to reduce cooking odors?

texts: As a young girl my mother always kept a bottle of "Air Wick" under the kitchen sink. When she cooked cabbage, cauliflower, broccoli, etc., she would open the bottle, pull out a green sponge that was on a wire, and place the opened bottle on the counter. It absorbed the strong odors of those foods that would normally penetrate other rooms. Today when I cook those same vegetables I don't notice those strong odors of my youth. Have those vegetables been genetically altered to reduce their strong, lingering odors?


texts: How does HBeAg change to Anti-HBe in acute hepatitis

texts:
I am thinking this figure

which can also be drawn like this

How does HBeAg change to Anti-HBe?

There are some triggers that stimulate Anti-HBe production after HBeAg level is done.
I think they can Anti-HBc.
There must be other mechanisms too.


texts: What risk to DNA does long-term exposure to low-dose radiation pose?

texts:
A new study from MIT scientists suggests that long-term exposure to low-radiation poses no risk of DNA damage for mice (it is also important to note that mice are unusually susceptible to cancer). So apparently there may be a threshold for radiation damage to DNA.

But is this study conclusive? What are some other studies that show the biological effects of long-term low-dose radiation on DNA?

There are some studies that do show increased rates of cancer in frequent flyers. So are are we going to reconcile this finding with the finding above?


texts: Do eukaryote cells contain DNA that isn't part of a chromosome or located in the mitochondria?

texts:
I specify eukaryote in the title, but I'm also interested if this question isn't applicable to eukaryote cells in general but is to humans. I was reading "RNA-seq: An assessment of technical reproducibility and comparison with gene expression arrays" (John Marioni 2008).

In the results it states

"By these criteria, 40% of reads mapped uniquely to a genomic location, and of these, 65% mapped to autosomal or sex chromosomes (the remainder mapped almost exclusively to mitochondrial DNA)."

I couldn't help but notice the "almost exclusively to mitochondrial DNA". Almost exclusively? Can DNA be found in places other than chromosones or mitochondria? Perhaps I'm interpreting the sentence wrong. Any pointers would be appreciated

Thanks


texts: Does a presence of ants on a plant mean that the plant has been infested by aphids?

texts:
Ants protect aphids from their predators (such as ladybirds):

  Aphids and other hemipteran insects secrete a sweet liquid called honeydew, when they feed on plant sap. The sugars in honeydew are a high-energy food source, which many ant species collect. In some cases, the aphids secrete the honeydew in response to ants tapping them with their antennae. The ants in turn keep predators away from the aphids and will move them from one feeding location to another. (source: wiki: Ant)

Does a presence of a large amount of ants on a plant in my garden (especially fruit trees, willow trees, flowers, vegetables) mean that the plant has been infested by aphids?

It's easier to spot the ants rather than the relatively smaller aphids so I am wondering if I may use this as a trigger for using an anti-aphid pesticide before the aphids start causing visible damage to the plants.


texts: Does loss of dopaminergic neurons totally eliminate voluntary muscular control?

texts: Breathing is a function that is not only autonomic, but can also be temporarily overridden and placed under voluntary control. In fact, you are now breathing manually. Now, suppose that someone has completely lost the ability to voluntarily control his/her muscles due to destruction of the brain's dopaminergic neurons in the substania nigra (such as due to Parkinson's Disease or MPTP poisoning). This would normally result in total paralysis of voluntary muscles and inability to move. Would that person be able to breathe manually if he/she so wished, or would he/she only ever breathe autonomically? What about defecation (Which requires one to voluntarily relax the anal sphincter)? What about rolling the eyes?


texts: How can synonymous mutations lead to cancerous or tumorous phenotypes?

texts: After analyzing DNA sequences of an oncogene from many human cancer patients, you found that synonymous substitutions occur in a specific codon of this oncogene. Assuming that these synonymous substitutions do not exist in normal populations but do contribute to tumor development, what would be possible mechanisms that would explain how such alterations can lead to tumor phenotype?


texts: How, when, and where did the very first life in the universe exist/formed

texts:
Do we know about the very first life, how it is formed? or from where it originated in the universe?
How life is fromed in our planet earth??
Life require conditions for survival or it can create favorable conditions


texts: Does the cellular response to every receptor work the same way?

texts:
I heard somewhere that activating any receptor results in the same intracellular response (signaling) which involves NF-κB. If that is true, I hardly understand how the cells distinguish between different types of stimulis coming from different types of receptors. I guess I am missing the point... :S

Figure 1 - signal transduction - source

If you check this picture about signal transduction. What you can see that there are about 10 arrows pointing to the inside of the nucleus, and there are about 10 receptor categories involved. Afaik. there are much more genes in the nucleus, so how is it possible to regulate the expression of so many genes with only a few signaling pathways?


texts: What does it take to start producing(cultivating) probiotics?

texts:
Is there a DIY way?
Is it possible to make a bacteria strain from scratch based on an existing one ? (for example lactobacillus reuteri).


texts: Are similar smells usually based on similar chemicals?

texts: Building off of this question: Why does freshly cut grass smell like a watermelon?, is it usually the case that things that we perceive as having similar smells are, in fact, the same or a similar chemical hitting our noses (as in the case of cis-3-hexanal in watermelon/cut grass), or is it often a cognitive thing (we're bad at parsing smells, so when confronted with a new smell, we fish around in our experience to find something that seems familiar, even if there's not much chemical similarity)?


texts: Is it possible for virus infected cells to continue to present a self-antigen on the MHC1?

texts:
Forgive my ignorance, as I'm new to immunology, however it seems like there would be some amount of positive selective pressure for viruses to develop the ability to continue to present the host's self-antigen on the MHC1 of a newly infected cell, thereby disguising the infection from the body's immune system (or at least from the cytotoxic T cells).

Is this in theory possible? Or is there a reason it cannot occur.


texts: In the transition to multicellularity what function becomes specialized first?

texts:
It's my understanding that in the transition from single celled to multi-celled organism a lineage will transition between stages where existing in a colony of cells is optional to one where it is obligate. Integral to this process is the parts of the colony taking on specialized roles in the colony's survival. First is tissues, and eventually full blown organs.

With that as background (please correct any misconceptions), which job tends to be taken over by specialized cells first in the transition? The three main ones in every multicellular organism I can think of are: digestion, structure (including skin and any rigidity), and reproduction (please suggest roles if I missed any, or over-included). Is there a single answer to this, or does it vary between lineages?


texts: What is the name of this bird from Tanzania?

texts: I took this picture in late 2018 in Tanzania. The Birds of East Africa book does not include it and I've been unable to identify it looking on the web. Can someone help me identify it, please. Thank you!


texts: How does kissing burst a person's ear drum?

texts:
A young Chinese woman was left partially deaf following a passionate kiss from her boyfriend.

..

  The kiss reduced pressure in the mouth, pulled the eardrum out and caused the breakdown of the ear.

Source - BBC News

How exactly does this work though? With me not immediately being familiar with the inter-mechanisms of the mouth/jaw/ears, I'm not able to so easily discern the cause-effect of this; also, most all literature I come across is anatomically oriented, like this, as apposed to perhaps more "functionally" oriented.

Follow-up / Accenting question: is there any kind of anatomical disposition that would make the woman more susceptible to this happening? I mean, there are millions of people that partake in "passionate kissing" every day, however, this is the first I've ever heard of it bursting someone's ear drum.


texts: Is Cas9 unique in it's ability to act in response to a specific DNA sequence?

texts: As a computer scientist, I'm interested in the ability of the Cas9 protein to function as an if-gate for DNA. It opens up so many questions for me. Right now the protein works as "if the sequence matches, cleave", but perhaps you could customize it to do "if the sequence matches, [do arbitrary action]". However, I'd feel very dumb if I got all excited about this and it tuned out "no... there are plenty of things that function as [if sequence matches], the real revolution of CRISPR/Cas9 is... [something else]". Is my fear qualified?


texts: Plasmid transformation yields only empty vectors

texts: I have to electroporate pMAD cloned with an insert of 7.4 kb in my S. aureus isolate. When I electroporated in RN4220 I had no problems but when I put it in my isolate I just recover few colonies and they have the empty plasmid. Has anyone had this problem?


texts: What are the binding sites (or receptors) of cortisol?

texts:
I am in the process of a OCR GCSE Case Study, and my question is "Do the benefits of anabolic steroids outweigh the risks, which has an obvious conclusion.
I need to know the scientific name, or a scientific analysis of why it causes an increase in protein synthesis,  for the binding of cortisol to understand this quote:"Anabolic steroids may block the binding of cortisol to its receptor sites, which would prevent muscle breakdown and enhances recovery.". For without enough understanding i can't explain it.


texts: Can a frog swim on its back, or it can use only the classic frog style? Does any (not specifically marine) animal exist with many different swimming styles, just like humans?


texts: What are the exact characteristics for something to be considered a novel virus?

texts: I've heard viruses being referred to as "novel" - is there an exact definition for what this means?


texts: Could we breed a dog to the size of a thumb?

texts:
We've gotten from a wolf to a small breed such as a chihuahua. So the question is: can we go even further and have a dog as small as a thumb (adult dog)?

If not, what are the factors that limit the smallest size of a dog breed? Is it limitations in genetics, or some physiological reasons which would prevent such small dog to survive?


texts: There are linear and rotary molecular motors in the cells. Do any of them have a fixed or stable frequency or speed?

texts: Are there any linear, rotary or oscillatory molecular motors in the cells which can have fixed frequeny and which can be used as a reference for elapsed time timer? This question is with relevence to my earlier question 'Is there a realtime molecular clock within the genome to co-ordinate the developmental sequences in an embryo?'


texts: How can carnitine enter the mitochondrial matrix without OCTN2?

texts:
Some people have defects on the gene SLC22A5, giving them problems with their OCTN2 transport protein (Organic cation transport).

OCTN2 transports carnitine into the mitochondial matrix where it can be used to create cellular energy.

Treatment indications for individuals with the defect on SLC22A5 includes oral or intravenous carnitine supplementation.

But one piece is missing...

If their OCTN2 is defective, then how does supplementing carnitine solve the problem? If they are deficient or lacking in OCTN2, how does carnitine even enter the mitochondrial matrix? (with no functional OCTN2 to transport it through?)

But the condition of these patients often improves with supplementation. So the carnitine is getting in there somehow.

Is there another route via which carnitine enters into the mitochondrial matrix?


texts: How much solar energy required to produce enough food for a herbivore?

texts: Just curious, how much solar energy can power an (herbivore) animal? Specifically, is it enough sunlight on Mercury (4 to 10 times brighter than on Earth) to "feed" a zebra? Will it be sufficient at 10x more effective photosynthesis? Notwithstanding lack of atmosphere, water being buried deep and other minor problems, of course :)


texts: Does anyone know what kind of caterpillar this is?

texts:
I was out hiking, and was walking along the side of a road, and saw this little guy on some gravel. Hes a light blue/grey color, hairy, spotted with red,and looks like he has horns and a tail. I've been trying to search for what species it is. If anyone knows, please share!

(Click to view full image)


texts: How to determine if this blood disorder is recessive or dominant?

texts:
This question is from "Concepts of Genetics," Klug & Cummings, 10e.

"Thalassemia is an inherited anemic disorder in humans. Affected
individuals exhibit either a minor anemia or a major anemia.
Assuming that only a single gene pair and two alleles are
involved in the inheritance of these conditions, is thalassemia a
dominant or recessive disorder?"

I know from a quick Google search that the disorder is recessive, but how would I come to this conclusion based on the question alone?

Edit: I've spoken to my professor, and he shared his opinion that is essentially the same as canadiener's answer. Thanks to everyone that replied!


texts:
I found it on the cedar siding of my home in Houston, Texas.

It was quite small, I'd estimate 1cm in length. I did not observe it move up or down the side of the house, but when I touched it gently and it did bend over.


texts: Do drugs always degrade after they have passed their expiration date?

texts:
I have been wondering for some time whether several drugs really have an expiration date.

Let's narrow the scope and think about only "common" drugs, e.g NSAIDs, antibiotics etc.
For example, would antibiotics in the pills get deactivated or decomposed?


texts:
I am carrying out a study of lactobacilli isolated from different samples.
Genus and species are identified using a sequenced 1000pb long 16S fragment in BLASTn.  I cannot distinguish between L. casei and L. paracasei because they have same score and query coverage when they appear as a hit for a sequence.

I read somewhere (cannot remember where) that L. casei and L. paracasei both should be itnegrated in a single L. casei species and their differences should be considered at strain level.

Should I focus my discussion on this fact? Or are they really different species?


texts:
I am not a biologist, but I have always wondered why my body hasn't learnt to deal with the HSV-1 virus. I understand it reamins dormant for a while and things like stress or the common cold can trigger it. I get cold sores about twice to even four times a year and I have had them since being quite young.

Why hasn't my immune system learnt to recognise it and eliminate it?


texts: Why do some protocols require prewarming a liquid medium before inoculating?

texts:
For example, in this protocol for E. coli competent cell preparation, it says:

  Plate 10 uL E. coli BL21(DE3) cells on a LB-agar plate; incubate overnight (12 hours).

  Prepare 500 mL SOB medium so it can be pre-warmed in the 37 degrees Celsius incubator the day before.

  Pick a single selected colony and inoculate in 5 mL of SOB medium and grow for 16 hours at 37 degrees Celsius and 250 rpm in a shaker.

  Inoculate 500 mL of prewarmed SOB medium with 5 mL of the fresh overnight culture.

and then in the protocol for overexpressing proteins after transformation of these cells, I basically follow similar steps as above but this time, without prewarming the large-scale inoculation lqiuid medium. Why is that?


texts: Does a critical mass of infected individuals exist after which mutations will overtake vaccination attempts?

texts:
As we know, all organisms have a probability to undergo mutations when they replicate. For every infected individual with the Covid-19 their bodies are environments in which the SARS-CoV-2 may mutate beyond existing vaccines.
Therefore, as the number of infected individuals increases, there will come a point where mutations in the SARS-CoV-2 would occur faster, perhaps even concurrently in different countries, than vaccines may be developed and deployed to stamp out the virus once and for all.
So my questions are as follows: is there a critical mass* of infected people, beyond which our existing vaccine development & deployment time frames will not be able to cope with? Do we have an estimate of this number?
*I understand this is not a single, fixed number but a fuzzy, probabilistic range.


texts: What is the direction of current flow in myelinated nerve cells?

texts:
Is it correct to say electric current flows through the extracellular space, or cytosol of a nerve fiber during impulse conduction?

I know that an impulse is actually a change of membrane potential which is transferred along the length of a neuron through transfer of ions (by a series of ion channels and pumps).

In myelinated axons our professor told us the following:

  When a nerve impulse propagates along a myelinated axon an electric
  current (carried by ions) flows through the extracellular fluid
  surrounding  the myelin sheath and through the cytosol from one node
  to the next.

How exactly does the current flow in myelineated nerve fibers?


texts: How does axon guidance system precisely targets specific axons?

texts:
Axons find their way to the terminus by responding to axon guidance molecules (AGMs) that attract and repel growth cones or make them stir. This I understand.

Through a very specific combination of AGMs, a precise path can be layed out that an axon cone will follow even across half the brain. This I also understand.

What I don't understand is that in developing brain, there are millions of axons moving to their termini at the same time, and millions of AGMs released all over the brain. When an axon departs on a journey to reach an AGM at the opposite end of the brain, it will probably pass by thousands of other AGMs and yet ignore them all.

When an AGM is released, there are like thousands of neurons nearby, and yet they all will ignore it but some single neuron across the brain will reach for it.

I can think of two possible explanations:

There are unique AGMs for every neuron that no other neurons will
follow (but it doesn't seem to be the case).
There are somehow very specific instructions wired into EACH neuron aka ignore five netrins, then follow the sixth, then ignore two more, and then follow the ninth one till you reach it (but how is it possible to program every neuron in the brain like that?).

So, how does it work in reality?


texts: Can Thraustochytrids such as Schizochytrium do photosynthesis?

texts:
I know they belong to the phylum of heterokonts and that they are being heterotrophically grown on an industrial scale but I can't seem to find any reference to them being grown photoautotrophically. People call them marine algae yet there is no mention of photosynthesis.

I did find this paper which says they have several carotenoids so I assume they have those because of their LHC's and photoprotection. It would be great if anyone had some more detailed information (papers) regarding their properties.


texts: How is green fluorescent protein distributed while inside an organism?

texts:
I would like to know a relatively simple thing, but something I wasn't finding the answer to.  When fluorescent protein is used in a relatively large, non-transparent animal, like a mouse, or theoretically a dog or a human, how is the protein generally incorporated into the tissue?  I suppose that it would bind to elastin and otherwise it could be transfected into different cells in and throughout tissue, both around the skin and deeper.  However, wouldn't it only be useful near to the skin, since ultraviolet light and visible light would penetrate a limited distance through tissue?  Then again, a relatively bright light source could possibly produce light from deeper in tissue.  I'm not quite sure.  It's a relatively simple question, but I appreciate it.

(Edit): I may have been a little vague with the question, a more specific version of the question I asked would be; given the brightness of a fluorescent light source that is directed at fluorescent protein filled tissue (with UV assumed to be close to the visible spectrum) and the portion of that light which is converted to visible light, approximately how could you calculate the relative brightness of the protein at a certain depth in the tissue.  Of course it probably is very difficult to get accuracy with that because that would depend on the portion of fat, muscle, collagen, etc in the tissue.  But if there's something rough and general, like the depth of the protein would reduce its relative brightness proportionally to the natural log per millimeter or something, that would be fine.


texts: What is titratable acid? Why is ammonium not titratable acid?

texts: What exactly do we mean when we use term titratable acid in renal physiology? Why is ammonium not considered a titratable acid?


texts:
Are roe (fish eggs, caviar, etc.) single cells?

I have tried looking this up on google (sadly, to no avail), and I am guessing they might be multicellular (like bird eggs) or consist of one cell plus corona cells, or indeed unicellular.


texts:
Why can't humans drink sea water?

It would seem to be a huge evolutionary advantage for an animal to be able to drink sea water rather than have to rely on fresh water, and it's provably not impossible due to the existence of sea mammals that must filter the sea water somehow.

Could someone explain to me any likely reasons that this is the case?


texts: Controlling the pursuit path of the human eye

texts:
The human eye scans images by panning focus along a certain path. Stork et al. (2002) revealed that there is a feedback process involved in moving ocular focus along a path that produces minimum muscular stress.

This got me thinking that, possibly, I could augment a video such that I slightly blur most of the image in each frame leaving a path (with some significant width) of the unblurred image or a path of clarity, if you will, to "control" a third party's ocular pursuit path. I hypothesize that this control would be won from imposing a path of clarity , because the eye adjusts it's pursuit path to reduce stress.

Could you help me to decide if this is even remotely possible?

Thanks in advance! :)


texts:
The following is an illustration rom my book of the phylogenetic tree of 6 animal phyla (the red stuff is mine):

I think what's causing some confusion is that there are no names/years at the circled nodes.

My first question is, was there an actual population between nodes (ex.) 2 and 3?

I would like to check if my understanding of the tree is correct:

Before node 1, there was a population which split into two populations: Porifera and the population between nodes 1 and 2 which we will call population 1-2. This population is unnamed on the diagram, either because we don't have a name for it, or because members of that population no longer exist, or to keep the diagram simplified.

Next, after some millions of years, population 1-2 split into the Cnidarians and population 2-3. Etc.

Is my understanding correct?

Thank you very much.


texts: Population genetics and the fitness probability distribution. Why is the arithmetic mean all we need?

texts:
When recording change in allele frequency in diploid, bi-allelic, infinite and panmixic population we usually use this kind of equation:

$\delta_p = \frac{p * q *( p (w11 - w12) + q * (w12 - w22))}{\bar{w}}$

$\bar{w} = p^2 * w11 + 2*p*q*w12+q^2*w22$

$\delta_p$ = change of $p$ (frequency of one of the allele) from one time step to another

$w11$ is the mean fitness of individuals of genotype 11. $p$ and $q$ are the allele frequencies.

The only indicators for the fitness distribution is the arithmetic mean. Why don't we include other indicator of the probability distribution of fitness? The skew, the sd, the median for examples. Could you argue why we don't need to care about the probability distribution of fitness of individuals with genotypes 11 (for example)? In other words, why is the mean fitness (=w11) a sufficient statistics?

I wouldn't be able to answer if one asks me:

Why don't you take the median instead of the arithmetic mean?"
Why don't you care about the variance, the skew (or any other moment) of your distribution?
What if the traits were not countinuous but discrete (sex is a discrete trait for example)?


texts: Regarding apoptosis and turning it 'back on'

texts:
Is there some chemical or chemicals or even special molecules that can be 'injected' into cancer cells that will turn any Apoptosis mechanisms 'back on'?

Or maybe chemicals and/or molecules that might cause a certain gene or set of genes to switch to a configuration favorable to apoptosis?


texts: Neuroscience: zapping an axon connected to thermoreceptor

texts:
Let’s say an experimenter has an electrode that can give a shock to a single axon. She takes that electrode and zaps an axon connected to thermoreceptors in the hand of her subject.

I) What would the subject’s perception of the stimulus be?

II) Why?

III) If she zaps that axon AND ONLY THAT AXON so hard that it destroys the axon, would the subject feel pain?


texts: What is Sequence based method for prediction of continuous B cell epitope? What is the algorithm/procedure of this method? Can someone please explain this to me in simple language?


texts:
In this book, they talk about the majority rule.

  Majority rule, which retain s the edges present in more than 50% of the trees.

They used that rule also in this article (Grant, P. R., and B. R. Grant. 2010. Conspecific versus heterospecific gene exchange between populations of Darwin's finches. Philosophical transactions of the Royal Society of London. Series B, Biological sciences 365:1065–1076.)

  We applied the majority rule (p . 0.500) to assign individuals to
  groups.

This was when using the software STRUCTURE.

I haven't found a convincing definition of the "majority rule" except definition in politics.

So what is the "majority rule" and how is it applied?


texts: What values to be taken for x-axis and y-axis?

texts: I did a lab on form and function in photosynthesis and I recorded the values of absorption spectrum in spinach chlorophyll extract. I have the following data and I need to draw a graph. I didn't understand what I should take for x-axis and for y-axis. Can anyone please explain this.


texts:
1/330 of white people in south Africa have a disease called Porphyri.

What is the frequency of the gene if it is inherited autosomal recessive?

This one I understand. The genotype frequency is $q^2 = 1/300$ so the gene frequency has to be $\sqrt{1/300}$ as it is inherited aa.

What is the frequency of the gene if it is inherited autosomal dominant?

Here's where I run into trouble. So if $p$ is the dominant allele and $q$ is the recessive allele the allele frequency has to be $2pq+p^2$ right? As we can either see them as $Aa$ or $AA$

But my book says it is $2pq+q^2$ and then solves it algebraically by pretending $q^2$ is so close to 0 that it's not in the calculations. I strongly disagree that $p^2$ is very small if I am right with my assumption. Which one is right and why?


texts:
I believe that there are predator/prey combinations where the prey can easily spot that the predator is not hungry and will not try to flee from it. I’m thinking, for example, of gazelles who will happily graze in sight of sleeping lions. (Please correct me if this is already wrong.)

It seems to be sensible (in an evolutionary sense) for the predator to not put unnecessary stress on the prey. First question: Are there predator who actively signal that they are not hungry, e.g. by a certain sound?

And my second question: Is there such a combination where the predator will, in times of severe hunger, pretend not to be hungry in order to more easily catch a prey?


texts:
Related to my other question.
I know that the coelom is derived from mesoderm.

Coelom seems to form during organogenesis within 3rd and 8th week of embryogenesis.
However, that answer is not either enough exact or it is wrong.

I am reading the thing in Kimball 5e and Gilbert 9e, but cannot find an exact mention about the thing. I know for sure that the coelom develops within gastrulation and organogenesis, since it is forming from mesoderm.

When does coelom form exactly?


texts: Regarding the difference between cDNA library and RNA sequencing (Biochem. technique)

texts: I was wondering why establishment of cDNA library required the step of reverse transcription (i.e. turning the sequence into DNA) why not directly using the extracted RNA for sequencing and converting the U to T base? Why bother to have one more step? super super confusing


texts: How many proteins are in the Earth's proteome?

texts:
Humans alone have thousands of proteins. With that in mind, it seems like the total number of proteins among all species would be very large.

Are there any available estimates for how many proteins exist on earth in all organisms? I'd also be interested in how many of these are unique proteins as opposed to proteins that are very similar to other proteins, i.e an estimate of non-redundant proteins alongside the redundant proteins.


texts:
I have read that 1g of pure fat has 9 Calories.

If I dieted successfully in a way that did not cause me to loose muscle, and I had a cumulative calorie shortfall of 90,000 calories. Would that correspond to a reduction of bodyweight of 10kg? Or would it actually be a bit more, because presumably each kg of fat in the body is tied to a certain amount of water packaged with it?... and if so, how much more than 10kg?


texts: Do human genes get affected by irregular sleep and other factors

texts:
I'm new here so please go easy on me.

Do our genes-the ones that carry our appearance, intelligence and other traits get destroyed or lost due to irregular sleep, excessive body heat, smoking, drinking and other factors?

Asking cause, I have some relatives of mine with really good genes that are worth passing down but afraid that their children wouldn't get it because of the abovementioned habits.


texts: What does the phrase 'background level' mean?

texts:
I was reading BIOS Biochemistry and stumbled upon a phrase 'background level' in the following excerpt $-$

  The lac operon contain lacZ,lacY and lacA genes encoding $beta$-galactosidase, galactoside permease and thiogalactoside transacetylase, respectively, preceded by an operator site and a promoter. The operon is transcribed by RNA polymerase to produce a single polycistronic mRNA that is translated to produce all three enzymes. When lactose is present the background level of $beta$-galactosidase converts some lactose to allolactose, which induces transcription of the lac operon.

What is meant by background level? Does it refer to the basal level of transcription, the constitutive transcription of facultative genes?


texts: What does it mean for a species to be ancient?

texts:
When we say that a species like cockroaches is ancient, what does it mean exactly?
Does that mean that cockroaches haven't evolved for a long time? But isn't evolution always occurring? So is that because they haven't evolved as much and are very similar to their ancestors, ie they had a "very slow rate of evolution"?


texts:
Fisher's principle explains why sex ratios in most sexually reproducing species is approximately $1:1$. However, given that in humans and many other animals, males and females differ genetically, it seems that this should cause issues for Fisher's principle.
Say that the Y-chromosome of an animal had a mutation that increased the ratios of males to females produced by the animal. At the extreme, we could imagine a mutation such that the sperm of the animal only carried Y-chromosomes. Although, by the Fisher principle, this would be bad for the overall number of offspring produces by the animal, it seems it would be good for the Y-chromosome itself, since it will now be present in all descendants of the animal (since they are all male), rather than only half the descendants. I would therefore expect that such a mutation would spread, skewing the sex ratios away from $1:1$.
Have scenarios like the one I outlined above actually occurred in species? If not, why not?


texts: Two heterozygote mice for skin color are reproduced. Find the probability that in 3 children 2 will be dark and one white

texts: Two heterozygote mice for skin color are reproduced. Black is dominant to white color. Find the probability that in 3 children 2 will be dark and one white. How did you do the ordering. Well I found it that in F1: 1/4 are AA, 1/2 Aa, 1/4 aa or 3/4 black and 1/4 white.Now nI think I should multiply the chances: 3/4*1/4*3/4, but it would be according to an order. What should I do? Is my answer correct?


texts: What does the final (Illumina) RNA-seq library contain? ss cdNA or ds cDNA?

texts:
I guess the oligos on Illumina's flow cell only hybridize to to single-stranded cDNAs (sscDNA).

However, when I read the TruSeq protocol (googled: TruSeq® RNASample Preparation v2 Guide) at the PCR step (AmpPCR, page 41) it looks like that the last cycle (d) is just elongation.

Therefore, since no denaturation (separation of dscDNA strands) happens, the final library input to Illumina should contain only dscDNAs which do not hybridize to flow cell's oligos!

My question is that then: when does denaturation happen? Inside Illumina? Or am I missing something?


texts: What is rotational diffusion and lateral diffusion in plasma membrane?

texts: There are no good reads on internet. The idea that I have formed so far of these topics, is that lateral diffusion is translational movement of protein in a leaflet.


texts: Is it possible for an organism that is polypoloid with an odd number of sets of chromosomes (e.g. 5 sets) to be fertile?

texts: Is this possible, since there is five sets, there would be an unequal separation of homologous chromosomes during anaphase I of meiosis?


texts: Why is 'Grudger' an evolutionary stable strategy?

texts:
I am currently reading 'The Selfish Gene' by Richard Dawkins, which I am sure many here have read. The topic are evolutionary stable strategies (ESS) regarding cooperation.

I apologise for the long question. If you are already familiar with the topic and Dawkins' model of Cheat, Sucker and Grudger: my question is, how can Grudger be an ESS if it could be invaded both by Suckers (because they have no disadvantage against Grudger) and Cheats (because a Cheat minority is unlikely to meet the same Grudger twice, turning Grudger into Sucker effectively)?

More detailed:

The model

Near the end of chapter 10 (p 185 in my version), Dawkins uses a model of birds who clean each other of parasites, therefore helping in survival (as cleaning themselves they cannot reach every spot of their body). He defines three different behaviours for the model:

Sucker - birds who indiscriminately help and clean other birds
Cheat - birds who let others help them but never do so themselves
Grudger - birds who help others and remember who they helped. If the same bird does not help them later (reciprocate), they will not help that bird again.

Claim: Cheat and Grudger are ESS

He claims that both Cheat and Grudger in themselves are ESS - that is, if all birds behave this way, none of the other behaviours can develop because they will be immediately penalised by lower chances of reproducing.

The part that makes sense: Suckers is not an ESS, Cheat is

Sucker is of course not an ESS. If all birds were Suckers, any Cheat that developed would have a huge reproductive advantage and Cheat genes would overtake the population.

Being an ESS makes sense for Cheat. If all birds cheat, nobody will ever be helping each other. A minority of Suckers would be spending all their time helping and not getting anything in return, Cheats have the advantage and Suckers die out again. Grudger would be unlikely to meet a Cheat who they helped before again, so they too will spend all their time helping and die out again.

The part that confuses: Grudger is an ESS?

But Dawkins also claims that Grudger is an ESS, and he seems very confident in that. Now I don't consider myself enough of a smartypants to claim that he's wrong, but I don't understand how Grudger can be an ESS. If all birds behave in this way, and for any reason some Sucker developed - the Sucker would have no disadvantage. All birds would still always be helping each other, so nothing would stop the Suckers from propagating equally well as the Grudgers, invading the gene pool. That's already the ESS broken, but even further, the presence of Suckers would mean that if Cheats came up, they would have a realistic chance of surviving - Grudgers would shun them after having helped once, but if the number of Suckers is large enough, Cheats will have an advantage.

Moreover, back to the initial setting of Grudgers only - if a Cheat developed, he would be unlikely to meet the same Grudger twice, receiving the benefit all the time but never paying the cost. He would have an advantage and spread Cheat genes.

The problem

I'm not familiar enough with how these kinds of models are calculated in order to state chances that Cheats will take over completely, but however I think of it Grudger does not seem to be an ESS to me.

Does anyone have an explanation why Dawkins is so sure that it is? Seeing as in nature we do see patterns like Sucker and Grudger all the time, I must be missing something important here.


texts: Why does vision gradually becomes dimmer in bright setting?

texts:
I don't know if this is only happens to me, but if I am in a well lit room and I stare at one point or just look at one area without moving my eyes around my vision in that specific light setting becomes dimmer. I can look around and everything feels like it is dim and lacks the bright light that originally radiated through the room. So I was wondering how and why this happens? I suspect(I am quite dusty in my ophthalmology) my eyes maybe relaxing and taking less notice of the intensity of the light, if so what makes it do so? As a side note this occurrence hasn't affected my life, I am just curious as to why it happens. Another note response to some of the comments, this isn't like walking into a well lit room and get bombarded by the light and eventually adjusting to it. This is like sitting in a well lit room for 15 minutes and then things just become dimmer and less intense. I've also observed this only happens with artificial light and may have some link to the type of light bulb.

I would like to add that this happens if I concentrate on one area or object. So if I were to read a book or be on my laptop, the light around me would feel dimmer. I suspect it has something to do with my eyes focusing on one source, if I were reading a book and this happens, the words become more prominent.


texts: Where can I obtain the sequence of the E. coli ribosomal RNA precursor?

texts:
I have found separate sequences for 16S rRNA (from the small subunit) and 23S rRNA and 5S rRNA (from the large subunit). I need the full precursor rRNA sequence, which I cannot find.

However the complete annotated sequence of the E. coil genome is available:

https://www.ncbi.nlm.nih.gov/nuccore/U00096.3?report=fasta

Does changing the T to U of this sequence give me the complete rRNA sequence?


texts: Change in conditions of an ecosystem lead to change in organisms

texts:
Let's think about the slash and burn method and its effects on the ecosystem.
Cutting down trees that rise all the way up to the canopy would expose the plants at ground level to more light, so would change an abiotic factor so changes the conditions required for survival. These plants are not adapted to the high light intensity so would find it hard to survive and compete, through inter-species competition, with newly arrived plant species that are much more adapted to the extra light intensity.

Obviously this would cause a dramatic reduction in the numbers of the previous plant species and would result in migration of the animals due to lack of food, assuming they can't feed on the newly arrived plants, and a change in the food chain.

In what ways do this affect the local and regional ecosystem, and what problems could it produce (both from an ecosystem and human perspective)? These types of land-use changes are often seen as problematic in conservation biology (as "...a bad thing"). Wouldn't the new plant species bring in new animals that do feed on them and a new equilibrium be reached just with different species? Is it to do with the reduced biodiversity or danger of extinction of indigenous organisms?

As you have probably realized I don't exactly understand this topic perfectly and would appreciate any amendments or extra information to the paragraphs above.
Thanks in advance.


texts: Energy released during the production of ATP?

texts:
When glucose is used during aerobic and anaerobic exercise, how much energy is expended or required?

During aerobic exercise:

$C_6H_{12}O_6 + 6 O_2 \to ATP + H_2O + 6 CO_2$ + energy

During anaerobic exercise:

$C_6H_{12}O_6 + 6 O_2 \to 2 C_3H_6O_3 + 2 ATP$ + energy

For each of the reactions above what is the value of the '+ energy' part?


texts: Do bald people not grow hair, or does their hair simply fall out immediately?

texts: This image is not directly related but it made me wonder if there was a relationship between the nature of the hair follicle and baldness, namely that the follicle cannot 'hold' the continuously growing hair, and it constantly falls out in. I wonder if this is the case or if the hair literally just does not grow out from the follicle at all.


texts: How to tell the difference between mould and condensed milk and sugar

texts:
I have had sweetened condensed milk in the refrigerator for some weeks (or months perhaps?). The can was covered with aluminium foil.

I noticed some disk-like artefacts on its surface, which are harder then the rest of the product:

Full-sized photo

How can I know if this is mould or simply further condensed milk with sugar? Is this safe to eat?

If it is relevant: the content of sugar is 56 g per 100 g, while this product has 8 % of fat content.


texts: Atmospheric gas changes, and their effects life

texts:
I was curious how life on Earth, or an Earth-like planet, would be effected by changes in the gases which make up our atmosphere.

Assuming there is a similar level of oxygen in an atmosphere, could other gases be reduced or even replaced and still be able to maintain life as we know it?

Not really biology, but if the following could be kept in mind too that would be amazing:

[To give some context, I would like to ask how a sky could be light blue with a purplish hue, which supports some life larger than what we see on Earth, but still capable of supporting life which we find on Earth.

I am assuming a slightly higher percentage of oxygen is needed, but what other gases which are none lethal, but give a purplish hue?]

Thank you to all who take the time to give an answer, very much appreciated!


texts: Why are there splice variants within the same organism? What might contribute to the need for the feature?

texts:
I only know splice variants are produced by different combinations of introns and exons. I wish to know why there is a need of such function. Perhaps using the same amount of DNA sequence to produce multiple proteins saves genetic material. Also, I want to know what contribute to the need for splice variants feature (e.g. evolutionary pressure, the need to increase the complexity)

I find that in human, protein CD81 is predicted by Ensembl to have a lot of splice variants (http://grch37.ensembl.org/Homo_sapiens/Gene/Splice?db=core;g=ENSG00000110651;r=11:2398547-2418649;t=ENST00000475945). However, only 1 of them is characterized. Thus, splice variants seem redundant. Any examples of splice variants actually carry different function?


texts: Are the foramina of Magendie and Luschka genuine defects of the ependymal epithelium?

texts:
Question:
Are the foramen Magendie (or the median aperture) and the two foramina Luschka (or the lateral apertures) genuine defects of the ependymal epithelium? So the ventricular lumen truly communicates with the subarachnoid space? If so, how is the defect maintained? Also, what do the boundaries of the defects even look like?
Context:
The fact that there can be non-pathological defects in an epithelium is jarring for me, because I have always been taught that an epithelium consists of an uninterrupted layer of cells juxtaposed against each other, limited by a basement membrane on one side and encasing a lumen or facing the exterior on the other side.
So really there are no 'holes' in an epithelium, and even structures that might look like a hole, such as ducts for a gland, are in fact just invaginations of the epithelium.
I've been able to apply this concept to understanding other anatomical structures with no difficulty. If the foramina of the 4th ventricle are really epithelial 'holes' then this is a major anomaly. In fact, I cannot think of a single example other than this one in which a normally developed, intact epithelium (and a basement membrane) has a 'hole' in it.
Also if this is the case, how is the defect maintained? As far as I know, epithelia, when penetrated by trauma, promptly close the gap and re-epithelialize. I believe a persistent epithelial defect must have some kind of supporting mechanism that forces tolerance to such defects.
Lastly, I know almost nothing about cell polarity, but I've learned that that the surface of epithelial cells which faces the lumen is apically polarized, the surface facing neighbor cells is laterally, and the surface in contact with the basement membrane is basally polarized. Would cells at the boundary of the defects have their apical and basal surfaces directly in continuation with each other without an intervening lateral surface, having no neighbor cells to contact?
I've been searching the literature for quite a while, but nobody seems to be really bothered like me by the implications of holes being present in a normal epithelium. Perhaps I'm taking it too seriously and all that 'epithelia are uninterrupted layers of cells' talk is just a rule of thumb, a crude generalization meant to serve only pedagogical purposes. But these foramina of Magendie and Luschka are the only counterexamples to this maxim I could come up with so far. I believe that a rule this widely applicable must have some physiological basis, and therefore that deviations from it demand explanation.


texts:
The simplest malaria model is as follows:
$$\frac{dI}{dt} = \frac{\alpha \beta I}{\alpha I + r} (1-I) - \mu I$$

where $r$ is the natural death rate of mosquitoes, $\mu$ is the death rate of humans, $\beta$ is the transmission rate from infected mosquitoes to susceptible humans, and $\alpha$ is the transmission rate from humans to mosquitoes. However, for $I \ge 1$, $dI/dt$ is negative. Wouldn't that imply that the infected class is always shrinking from the start? How does this make sense?


texts: What are the longterm effects of pancreatitis?

texts: As the title asks, what are the longterm effects of pancreatitis?  Having one event, is the person more susceptible to have a recurrence, or are they at higher risk of other conditions such as diabetes?


texts: How are logarithmic trendline equations used to determine antibody concentrations in ELISA?

texts:
For example, say you have plotted a standard curve and managed to obtain a logarithimic trendline equation like:  y = mln(x) - b

And you are working with data that includes:
a) standards,their concentrations and absorbance readings (taken twice - with mean absorbance and blank absorbance also calculated)
b)samples (and their absorbance readings) that you want to know the concentration of
c) all the samples have been diluted two fold

Would you simply just rearrange the equation y = mln(x) - c  to:
x = (y + c) / mln
and input y value as being the mean absorbance readings of the samples you want the concentration of?

Are there any further steps after this? Or any I have missed out?

Is there anything I need to do with the dilution factor?
Do I have to do mean absorbance - mean blank, to get the correct absorbance readings to input as y or are the mean absorbance readings themselves sufficient?

Thank you


texts: Maximum RPM in zero-g before losing consciousness, spinning head-over-heels

texts: There are more than a few scenes in Gravity that I find dubious. Specifically the ones where people are revolving very quickly, either about their own center of gravity or at the end of a rather long pole. I'd guess we'd need to know how long the pole was, but I'm more concerned with a person themselves, just flipping around out there (and I suppose we'd need their height, or does that cancel out?). How fast can they spin until it's night-night? Is it reasonable to assume they should've passed-out in at least one of those scenes?


texts: Why is oxygen used up in eutrophication?

texts: This probably sounds pretty dumb, but wouldn't algae blooms produce a lot of oxygen? Although they would die out and decomposers would use up oxygen, is that more than what the algae produced?


texts: Why don't cells of aquatic animals burst?

texts: We know that if we keep plant cells in water, they don't burst because of a cell wall. But the cells of aquatic animals lack cell walls but they still survive. Why?


texts: Why don't we form immunity to some infections?

texts: I read another question, and its answers, about how vaccines work, but I don't see there, and and don't understand, why some infections can, seemingly, not be immunized against at all. For example, someone who gets the flu (or the flu vaccine) is immunized against that particular strain of flu for life (which was relevant, IIRC, when H1N1 came back a few years ago: many people above a certain age had immunity), whereas one person can get group-Α strep throat over and over again. Why is this?