texts: Are intracortical axon branches myelinated?

texts:
I found the following pictures of axon trees:

source

source (axons are red)

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

  Is it possibly true that the intracortical axon branches (i.e. those that don't leave the gray matter) are not
  myelinated?  (The first picture seems to indicate that they have at
  least a smaller diameter, making them slower?)


texts:
Saw these bugs inside the flat I'm renting (Switzerland), but I really can't figure what kind they are. What I can say about them:

They can do small jumps (up to 5cm I would say). It doesn't seem to be for locomotion, but as a means of escape when I try to catch one.
Size: about 1.5mm for the "big" ones. There are of various sizes down to 0.25mm for the really tiny ones (approximately; never managed to get one without crushing it). They behave much the same as the big ones (including the jumps) and are whiter in color.
They don't seem to live as a colony or in a nest (or I simply didn't find it), but sparsely on the wood floor, often near the baseboards. Found some on the walls, but those were the exceptions. They don't seem to like the bathroom.
Rather delicate; can easily be crushed.
Seem more active in the evening and at night, but don't mind going out during the day.
I live alone, without pets, but I don't remember having been bitten. I guess they don't feed on blood.
Seem to have long antennas (about half their body size) and small wings.

Side note: the flat is on the 3rd floor of a recent building (finished 14 months ago). I'm the first tenant.

An exterminator came and quickly classified them as some kind of flea. He put some pesticide on the baseboards, and their number is now quickly decreasing. But I'm still curious.

My first thought was "fleas" (because of the jumps), but I deemed them too squishy and not "vampire" enough for that. Also, I don't think that (what I assume to be) the young ones should be able to jump.

Then I thought "springtails", but I didn't see any furcula (granted, I don't have a good eyesight) and I don't think they are supposed to have wings.

One of them was nice enough to jump on some tape.

Top (on a ruler):

Front/Side:

Also, blowing on it (to open the wings):

Youtube video of one of them


texts: What cells would have the CD3 marker on them (other than T-cells)

texts: Do you know of any peripheral blood mononuclear cells that would express any amount (beit low or high) of CD3 on their surface (other than T-cells)?


texts:
Humans grow most quickly when young, and to a lesser extent in preadolescence and early adolescence. However an equilibrium is then reached in adulthood, typically at around 1.6/1.7 meters tall.

I have found the age at which people "stop growing", meaning that they are at their tallest hight, is around the age of 21-25.

Why is it beneficial for humans to grow to 1.6/1.7 meters?

Why is there so so much variation in this, with some reaching there full height in there early teenage years?


texts: What species is this bug that appears in my bathroom?

texts: I'm trying to identify the attached. A few of them appear every day in my bathroom, never more than that, but new ones are there every day. Length is 2-3 mm, and location is the United Kingdom.


texts: Why are plant cells rectangular and animal cells spherical shaped?

texts: Is that because the plant cells have cell walls and animal cells don't, or is there a function performed by the different shapes? Perhaps round shapes assist the movement of cells?


texts: Do animals only breathe through one nostril at a time like humans?

texts:
Humans breathe through one nostril at a time.

Do non-human animals also do so, or do they breathe through both nostrils at once? Has any actual study been conducted on this topic?


texts: Scanning Electron Microscope images of wheat grains

texts:
I took SEM images of wheat grains but I see some granular particles on its surface and I don't understand what they are?

Is it some kind of deformation of the bran layer due to drying? Or is it the gold-palladium alloy coating which is done for SEM analysis of non-metals?


texts: Is cancer caused by vitamin B17 deficiency?

texts: I have read in an article on the internet that cancer is caused due to deficiency of vitamin B17 which has been removed from our diets long ago in the western food. But some people say that vitamin B17 does not work. So, is it deficiency of vitamin B17 which causes cancer i.e. can this vitamin really be used to cure cancer?


texts: Which bacteria have the highest mutation rate?

texts:
From my reading on M. tuberculosis, I know that this organism has a pretty high mutation rate due to uncorrected sloppy replication, which leads to a high rate of development of spontaneous resistance to treatment.

Are there species that can beat M. tuberculosis in this degree of mutation, due to polymerase sloppiness or other mechanism?


texts: Why aren't nucleic acids on Nutrition labels?

texts: All the other macromolecules are listed on the Nutrition labels and nucleic acids do have some caloric value, why aren't they on the nutrition facts?


texts: Epistasis: Why should a recessive allele be a hypostatic gene?

texts:
Let us take the example of Recessive epistatsis, an epistasis in which a double recessive gene mask the phenotypic expression of alleles  of another locus.
 (adapted from: An Introduction to Genetic Analysis)

An example from the same book:

  In  plant blue-eyed Mary (Collinsia parviflora), the biochemical pathway is as follows:

  The w and m genes are not linked. If homozygous white and magenta plants are crossed, the F1 and F2 are as follows:

  Complemention results in a wild-type F1. However, in the F2, a 9:3:4 phenotypic ratio is produced.

  This kind of interaction is called epistasis, which literally means “standing on”; in other words, an allele of one gene masks the expression of the alleles of another gene. In this example, the w allele is epistatic on m+ and m$^1$. Conversely, m+ and m can be expressed only in the presence of w+.

Interpretation & Question:

The gene product of m$^+$ is needed to form blue pigment from magenta. On the other hand, in the absence of w$^+$ allele (i.e. w w genotype), no magenta (precursor of blue) is formed so the phenotypic expression of m$^+$ allele(s) is masked. Now, what has m got to do here? $^1$ It is not encoding anything.

Note:

On referring other books I found they do not suggest a hypostatic gene to be recessive (as $m$ has been considered here).

My idea of recessive allele is that one that due to loss-of-function mutation either produces a non-functional variant of the protein or the same protein at a lower quantity.

Has recessive allele been considered an hypostatic allele here considering that it might be able to code normal functional protein at a lower rate?

Scope of answer:

Which concept should be followed? Why (ideally with citation)?


texts: Identify orange-brown, teardrop-shaped insect in central Europe that was found indoors

texts:
TL;DR Can someone identify the species of the insect in below picture? Editing of the wording of this question (if possible) to make it easier to find by using search engines is welcome.
I caught this insect and was wondering what species it was:

Here a milimeter-scale and an USB-plug next to it to allow to estimate the size (sorry that they are so unsharp but I hope it is sufficient to get the size):

I was not able to find it by reverse image search or by searching for some keywords using google. I also checked some questions here but did not find any that seems to be about such an insect.
Following description/keywords are added to help someone searching for such an insect to find this using word-search. If someone can formulate this more search-engine-friendly to make this more likely to be found, please edit or add a comment so I can edit it:

Teardrop-shaped
six legs / 6 legs
two antennas / 2 antennas
orange-brown / brown-orange
size about 3mm / 3 millimeters / 0.11811 in / 0.11811 inches (I hope my calculation from mm to in is correct)
if touched by glas or paper, it remained motionless for about 1 to 2 minutes
no wings / not airbourne / walking
able to walk up walls
it was found indoors
the region is central Europe

Many Thanks in Advance.


texts: Sansevieria species specification needed

texts:
What are the botanical differences between the species S. parva and S. senegambica? Please highlight the main ones.
I have 2 groups of plants. One with label "Sansevieria dooneri" (a synonym of S. parva) and one with label "Sansevieria senegambica" and sadly both groups look awfully the same at first sight.


texts: For a recombinant pUC19 plasmid with cut sites at Hind III and EcoO109i, does lactose need to be present for the gene of interest to be expressed?

texts:
I am growing E. coli transformed with the plasmid pUC19 with an insert of an enzyme in rat brain between the mentioned cut sites (EcoO109i and HindIII). I have isolated and created the recombinant molecule with custom gene synthesis so that the gene encoding for the enzyme easily ligates into the plasmid.
It is after the lac promoter and lac operator, so will I need lactose in the growth media for the enzyme to be made?


texts:
Do ants understand which way is up or down?

Could they differentiate between uphill and downhill?


texts: Ideal examples of Magnoliophyta Lilianae

texts:
What are the ideal examples of Magnoliophyta (Lilianae-to be precise) for a teacher to show students?
And, does anybody know exact name of this flower? Picture


texts: In bacterial conjugation, how do F+/F- cells detect each other?

texts:
I've just learnt about bacterial conjugation and while it is interesting info about early sexual activity in microbes, one aspect confuses me and doesnt seem to be mentioned in the material I read:

How do the donor/recipient pairs find each other?

While cells in a culture all can have physical contact as they move about, either the F+ cell inserts pili into various cells looking for some chemical stimulus or physical contact with a F- cell provides some data that lets it know it has touched a cell with which it can now perform conjugation.


texts: Why aren't animals diverse in phenotype?

texts:
I am not comparing a cat with leopard.

I am just saying that we humans are all one type of creature and we are diverse (I am not saying we are class of mammals and phylum of etc and kingdom etc, because my religion doesn't believe in it).

So consider the class of cats they are one type of species so why aren't they diverse in phenotype like us?

Why do other animals, plants, unicellular organisms not have diversity in their phenotype and how they can recognize each other, like a bird always brings food to his offspring and it can't make mistake by giving it to other offspring of its own species?

So can I say they aren't diverse because of in their meiosis division their chromosomes don't cross over and random assort (alignment)?


texts: What is the likelihood of a single human gene to the same gene from the other human?

texts:
The human genome comprises 3,234.83 Megabases and contains ~ 19,000 genes. It has been estimated that the genomes of humans are 99.9% identical. How likely is it that any single gene might vary from one individual to another? Assume an average length for a gene of 3 kilobases.

Is it still 0.01%, the same as for the whole genome? Why then we have the number of genes in this exercise, together with an approximate length?


texts: Is it impossible for some female songbirds to sing?

texts:
I have read that in northern hemispheres, most female songbirds can't sing (for example, the Blackbird). Things are different in tropical regions. Birdsong is for males in some species; it is utilized to defend territories and/or attract other females.
While it seems impossible that female songbirds can't perform complex songs, can it be possible for captive birds?
I have read some reports that females are able to sing after being injected with testosterone. But the interesting question is whether females can be trained to sing without testosterone injections or other interventions?
There is an article showing that for one songbird species it is possible to produce female birdsong without testosterone injection (while older research claimed, females sang only when treated with this hormone): https://www.newscientist.com/article/2151727-female-birds-that-used-to-be-silent-are-now-singing-like-males/
There are dissertations about birdsong and sexual hormones: https://research.vu.nl/ws/portalfiles/portal/42186406/complete+dissertation.pdf
And here it is reported that female songbirds sang after getting testosterone: https://journals.sagepub.com/doi/abs/10.3181/00379727-41-10631?journalCode=ebma


texts: Why apes started to contemplate and become altruistic?

texts:
I was asking this first on philosophy forums, but it is suggested, that answer could be found from evolutionary view of point, so here we go:

Again my question raised when thinking of myths, their origins, mysticism and religious institutions. It is said that prieshood came to existence, when ape first landed from trees to earth collecting and gathering fruits, hunting and then started to plant and farm. Whole agriculture was build organizating leadership of the society among whom were the priests and shamans who tried to understand natural forces with limited knowledge and superstition. Accelerating need for planning future, not only own family's, but whole society's future forced thinking process of humanized apes to become more involved with contemplating. Did some of the deep thinkers find that there was a dimension on meditation which is next to impression of using herbs and drugs to bring mental experiences, were they hallucinations, visions, calmness or anything similar alive? Thus they became ascetics and adept on focusing mind toward itself while other part of high class of the society became adept on aiming mental activity outward, improving skills to master matter and physical nature. On ancient times both still shared same concept of need of supernatural forces to be placated or otherwise controlled to get or avoid certain every day results.

This also brings up a huge evolutionary problem so to say. While apes, if they were just lead by rather unconscious instincts, they would have reproduced and build on the principle of the strongest is the leader. But when reasoning, ability to think "cunning plans" as stated by Baldric on Blackadder came to existence, then the most clever often won the game. But what is clever on the other extreme of the religious practice, self sacrificing and altruistic ethics? It feels almost unnatural, that religions evolved to direction, where ethic and moral rules fights against physical existence or surveillance of the individual. There is a strong hope of afterlife compensation, which explains some of it, but I'm still a bit struggled, why (and when) apes started to retire to the forests to meditate and rather practice altruistic ethics, loving enemies for example instead of getting justice and their own benefit fulfilled in first hand, instead of reproducing and fighting for their lives and space?

To bring whole question to modern life, I think zen buddhism is a good example of such practices brought to other level. While on the most plain form they don't expect belief on the existence of the self nor karmic relations of the acts, they still rather follow high ethics of the teachings of Buddha and live simple middle way life just being aware and mindfull of the things happening at the moment, which is the ultimate goal of the practice and life.


texts: Evidence against aging caused by loss of information in genome and epigenome in humans?

texts:
After reading Lifespan by David Sinclair I'm curious if there is any evidence against aging being caused by loss of information in genome and epigenome of 3.7*1013 cells in human body.
Specifically has anyone compared the genome and epigenome of the same humans at different ages?


texts: How can inbreeding be used for selecting mutations?

texts: I understand that inbreeding, after a number of generations of crossing genetically related individuals eventually yields homozygotes, however I can't seem to understand how it can be used for selecting mutations.


texts: A source for leaf architecture of different plant species/genus?

texts:
I'm currently working on extracting some features of the leaf architecture based on their images (like L:W ratio, laminar shape, ...). I use the Manual of Leaf Architecture as the reference. It is really great in mathematically describing the features and how to calculate them.

But, the problem is I am not able to find a source (a book, or a data set) to have this architecture of different leaves (plants). For example, whether the Acer genus has leaves with a certain (or a range of) L:W ratio or the laminar shape for this species is mainly ovate,....

Does anybody know any source of this kind?


texts: What is the dependent variable of a relative fluorescence graph?

texts:
So it was asked what was the dependent variable of this experiment. I know that as students, we're wired to think that the y-axis is the dependent variable while the x-axis is the independent variable (probably good that way, I dunno).

However, I thought that the dependent variable in this kinetics would be time. Since this has relative fluorescence from 100 to 0, isn't the change in fluorescence for all four conditions the same, while the only affected variable being rate (which in this experiment is more dependent on change in time)?

Sorry I can't give more information about the conditions of the experiment, it's a test question that I wouldn't be allowed to post, which is why I whited-out the conditions of each line. Any help would be greatly appreciated.


texts:
Recently I've came across a problem after trypsinization of my stably transfected CHO-cells. When I add medium to rinse off the cells from the bottom of the flask, there are usually big chunks of cells, which I almost cannot resuspend properly... I also tried to increase the incubation time with trypsin, but it did not help much.

Does anyone have a solution for this? The trypsin I use is the same batch as usual and in the meantime I also thawed 2 different freezing stocks, but I still have the same problem.

I also tried different pipettes, from 25 to 5mL. But I can pipette like a maniac up and down and up and down... still there are big chunks of cells floating around...


texts: Curious on the species of a large Orange Spider?

texts:
Heres the images of her:

She just laid a large yellow fuzzy sack of babies recently (Were pretty sure were just going to deposit her and her eggs in a grove in the forest soon)

We have lots of brown recluses here in North Carolina, but no idea what she is.

Climate: Humid, Tropical.

Zone: Sneads Ferry, North Carolina, United States.

Size: About 1.5 Inch, leg spans are about 1 inch on their own.


texts: Trying to differentiate between the three muscle tissues with small pictures

texts:
For an assignment I have to differentiate the three types of muscle tissues in these three pictures
.
I'm having difficulty seeing the striations and branches etc. because the pictures are so small. Am I missing something?


texts: Do changes in an organism's cell modify the genetic information it uses for reproduction?

texts:
What I'm actually interested about is whether a modification in one cell during the life of an asexually reproducing organism affects its genetic information? Which cell's genetic information is used during reproduction like budding, for example in the case of Hydra.

Or does the incidental advantage it could have given rise to disappear with the death of the organism?


texts: Is there any genetic similarity that defy evolution theory?

texts:
For example,

say species A is common ancestor of B, and C. Species B is a common ancestor of D and E.

We would expect that there will be more genetic similarity between D and E than D and C. And those genetic similarity must exist in B.

In other word, we won't expect genetic similarity that don't "cross" the common ancestor or the evolutionary tree.

The exception is probably genetically engineered bacteria.

That being said, am I correct?

Some people say that we have similarity with pigs and chimps even though our common ancestors may be to far off. That won't happen right?

To summarize

I expect that evolutionary tree will form a well, tree. Genetic similarity would infect "nearby" trees and can't jump between trees without connectors, such as common ancestors.

Is that what we observe for ALL species?


texts: What do the acronyms in C.elegans neuron names stand for?

texts: In this site, I see a variety of acronymic names for C.elegans neurons but what do these names mean (for example AVAL, AVAR)?


texts: Distribution of the number of clover leaves

texts:
Being no expert at all in this field I am just interested in emprical studies of the frequency $f(n)$ of clover plants with a given number $n$ of leaves.

I would suspect naively from general considerations that the frequency follows an exponential distribution.

Any hints are greatly appreciated.


texts: I touched this tree on my visit to South Africa and a huge rash developed on my body,please help,what is the name of this


texts: Approximately how thick is a single strand of cat (domestic housecat) hair?

texts:
I did a little research to lead me to finding the general range of width for human hair, which is anywhere from around 30µm to 180µm... approximately.

I'm trying to compare this to the width of cat hair, since I have been told (and it does seem a bit evident) that cat hair is much thinner than human hair in general.

I can't seem to find any information on this.  Does anybody have any answers?

Note:  I apologize if this isn't the right Stack Exchange forum for this question.  I wasn't sure where to put it, so I did an SE site search for 'cat' and this one seemed to be the most appropriate.


texts: Assume that a patient has chronic hives (itchy) on the skin. I understand that he has an antigen, which binds to IgE and eventually triggers histamine release, causing an allergic reaction. So is there any method to detect which molecule/antigen has bound to his IgE? (can we capture it with like what we do to obtain a 3d protein/molecule structure?)


texts: Worm type bug inside of stick? What is it?

texts: This bug was found on the wall of my closet in Seattle, Washington. It has been around 40-50°F lately, and it is winter. It looks like a tiny, brown, fuzzy stick/twig, but there is a hole through the middle of it. A tongue kind of thing comes out of the hole. The tongue thing is clear/tan and has a brown tip. The tongue is how it moves around and it looks like the tip sticks to the ground, and then it pulls the rest of its body/the stick part forward from there. It doesn’t seem to like it when light is shined on it (like from a phone flashlight) and goes back into the twig part when light gets shined on it. The twig part doesn’t seem to move on its own. The twig when the tongue is inside is about 0.5 cm.


texts: Given ATP synthase's structure, how can 3.33 protons ultimately synthesize one and only one ATP?

texts:
I am familiar with the structure and function of ATP synthase, but one small detail doesn't seem to make sense. It also happens to be a detail that seems very hard to express.

Depending on the organism, there can be from 10 to 14 c-subunits in the c-ring of ATP synthase. For practicality/consistency's sake, let's assume 10.

Every c-subunit is protonated (from the cytoplasmic side of the mitochondrion) and rotated almost 360 degrees within the lipid membrane before it is ultimately deprotonated, which releases a proton into the matrix. Thus, since the c-ring is 10 subunits big (in this case), 10 protons are being introduced to the matrix every 360 degree turn, which mean that 1 proton = a 36 degree turn.

These protons allow for the gamma-subunit to be turned at the inside of the hexamer (of 3 alpha-subunits and 3 catalytic beta-subunits) found below the rotor. The b-subunits are thus located 120 degrees apart. Every 120 degrees precisely, that beta-subunit changes shape, dictated by the rotation of the gamma-subunit, and enters one of the three states that ultimately catalyze one ATP from ADP and inorganic phosphate (since only one of the three states actually forms ATP). Since the gamma-subunit catalyses the formation of 1 ATP every 120 degrees, a full 360 degree rotation would yield 3 ATPs.

This is where things go awry in my mind. Within 360 degrees, 10 protons and 3 ATPs are made. Thus, that makes (10/3) protons per ATP, or 3.33 protons/ATP. When the gamma-subunit receives a proton, it rotates 36 degrees, but ATP formation only happens at precisely 120 degrees, and the only common interval between 36 and 120 is 360 (when 3 as opposed to 1 ATPs are made)!

EDIT: The gamma-subunit must rotate in exactly 120 degree increments, because we observe it do so, as shown here.

  More detailed analysis in the presence of lower concentrations of ATP revealed that the γ subunit rotates in 120-degree increments, with each step corresponding to the hydrolysis of a single ATP molecule.

Logically, this shouldn't happen though, since the closest increments of 36 to 120 degrees are 108 and 144.

To summarize: How can 3.33 protons ultimately synthesize one, and only one ATP, knowing that a literal third of a proton doesn't exist (excluding quarks) and that increments of 36 degrees can never add up to exactly 120 degrees?

References

“A Proton Gradient Powers the Synthesis of ATP - Biochemistry - NCBI Bookshelf”, n.d. http://www.ncbi.nlm.nih.gov/books/NBK22388/.


texts: Mature mammalian erythrocytes have all the characteristics of a eukaryotic cell except that they don't have a nucleus, they don't have any cell organelles. Does this mean that erythrocytes are classified as prokaryotic?


texts: If people with colorblindness lack one type of cone cells, shouldn't they be unable to recognize one particular color?

texts:
The 3 types of cone cells in normal humans allow them to view 3 types of colors and any color made from mixing and matching those 3.

So, 2 types of cone cells should only allow to view just 2 types of colors and any colors made from those two.

But that is clearly not the case.

https://en.wikipedia.org/wiki/Color_blindness#Red.E2.80.93green_color_blindness

  Protanopes, deuteranopes, and tritanopes are dichromats; that is, they can match any color they see with some mixture of just two primary colors (whereas normally humans are trichromats and require three primary colors).

Also, from personal experience, I'm colorblind and can see and differentiate all 3 red, green, and blue. It's just the hues between red-green and green-blue I can't distinguish much...

How exactly do dichromats see all three colors when they lack one type of cone cell?


texts: So many parakeets sitting on a tree with no leaves ?


texts: Sparking during electroporation of plasmid DNA into bacterial cells

texts:
During electroporation of bacterial cells (I work with Mycobacterium tuberculosis, but I think this applies to E. coli as well), sometimes I get sparking. I've read this is due to salts present, either in the DNA sample or the bacteria.

I use the Qiagen plasmid prep kit, which includes EB (Elution Buffer). This contains Tris-Cl. Could this be contributing to the sparking? Can you explain how this works? Does eluting with water instead of EB reduce chances of sparking?


texts: I spotted this shrub-like plant in California, USA.


texts: Absorption of glucose in small intestine

texts:
During the absorption of glucose in the small intestine, glucose enters the epithelium by Na+/glucose co-transporter by the concentration gradient of Na+. The gradient is generated by pumping 3Na+ out each time and the entrance of 2K+ by Na+/K+ pump. The K+ is then removed by the concentration gradient via the potassium channel protein.
My question is is it more favorable to use a Na+ channel protein to pump Na+ out of the cell to generate the concentration gradient? Or there are some biological significance for K+ to enter the cell and leave again repeatedly (e.g. maintain stable charge distribution in and out of the cells? Thank you.


texts: Where in the nervous system are synapses chemical, and where are they electrical?

texts:
Paraphrased from the Wikipedia article "Synapse":

There are two fundamentally different kinds of synapses:

Chemical synapses, which convert electrical activity in the presynaptic neuron into the release of neurotransmitters via the activation of voltage-gated calcium channels. The released neurotransmitters, which vary in type by cell, bind to receptors of the postsynaptic cell, giving rise to complex behaviors.
Electrical synapses, in which presynaptic and postsynaptic are connected by "gap junctions" or synaptic clefts capable of passing electrical current, resulting in rapid signal transduction.

Are there certain structures and locations in the nervous system that are mostly or exclusively chemical synapses, and certain ones that are mostly or exclusively electrical? Or, are they mixed throughout the nervous system?

For example, one might suppose that the neurons which transmit signals from brain to limbs might be electrical, due to the apparent advantage of fast transduction times in this scenario. On the other hand, it might be advantageous for the brain to be capable of more the dynamic, albeit slower, signal transmissions made possible by chemical synapses. Are these intuitions accurate?


texts:
Going out on a limb here (pun intended)...I'm writing a paper in which I need to refer to various sections of the human leg from upper thigh to knee to calf and ankle. However, "calf" covers a fairly large area. Without having to go into specific leg muscle identification (semitendinosus, biceps femoris, etc.) which could be confusing as they overlap and can be found with Google.

Is there a (standard) anatomical way to describe (cylindrical) sections of the leg from top to bottom?


texts: Why can't gametes of one species fuse with that of the other species?

texts: I have read that gametes of one species cannot fuse with that of another? For example the sperm of a dog can't fuse with the ova of a cat or a horse?


texts:
When Lions roar, or Dogs show aggression, they do that snort-roar thing. They're producing sound while inhaling. How did that come to be when all (?) other forms of sound involve exhaling?

Humans do produce sound while snoring, but that's merely a by-product of it.

And while people could very well speak by inhaling, they don't do that in their regular communication. Lions and Dogs do. Why/when did they decide that (inhaling sound production) was a better/more effective means of making sound?


texts: How many areas are there in Brodmann map?

texts:
I read Wikipedia claiming 52.
I heard that this can be extended to 54.
I see there is no limit of having more areas - just better understanding of the neuroblast migration and fibroblast too, probably.
How is this newer classification of Brodmann map done?


texts:
I am interested in understanding how the global population pyramid has changed in the last couple of centuries.

I have two questions:

1) Has this been calculated? Are there estimates of population pyramids from the 19th century? Or from the beginning of 20th century? The earliest I have seen is 1950 (below).

2) If it hasn't been done, how can I construct it? It should be possible to model the population dynamics using birth and death rates (I would be surprised if this hasn't been done, as it has many applications outside of demography - e.g. economics).


texts:
I'm a bit disappointed but after several hours of search, I could not find an official authoritative source for bacterial shape classification. I find a lot, I mean a lot of links but no original sources, even on  Microbiology society no source....

I believe a convention, workshop or another authoritative source must at one point have worked on this matter...


texts: Why are there more stomatal openings on the lower surface of a dicot leaf?

texts: This causes more transpiration to occur from lower leaf surface. What's the exact reason for why are there more stomatal openings on the lower surface of a dicot leaf?


texts: What is the specific use of a capsule in E.coli?

texts: In evolutionary terms, will the capsule cease to exist someday or will it improve ? Does it provide any boost to the organism in any way which harms us ? Can't we remove capsules or engineer E.coli without capsule ?


texts: How do non-dimorphic birds distinguish sex of possible partners/rivals?

texts:
Some birds, such as my pet Pionus chalcopterus, are not sexually dimorphic.  People can't tell them apart, and even trained avian vets are not 100% certain with an inspection probing the vent.

I understand that when not "in season" there is no physical difference as internal sex organs are atrophied to save weight.

But how do they tell the difference?

Do they have dimorphic markings that bird eyes (but not humans eyes) can see?


texts:
I'm fairly new to bioinformatics, so please be gentle ;0

Is there a way to query a particular gene using a script in R/Bioconductor? I'm particularly interested in Gene Ontology terms. There are many websites that, given the gene name, will return relevant GO terms. My question is, can it be automated?


texts: What is the difference between endometrial lining and endometrial stroma?

texts:
This is in the context of embryology whereby the syncytiotrophoblast erodes the endometrial stroma during the penetration and implantation of the zygote.

But I don't know the correct terminology of what exactly has been eroded.


texts: What will happen if a poisonous snake bites itself?

texts: I wonder if in general snakes are immune to their own venom. I would like to know studies or references about times snakes bit themselves and got sick or the contrary.


texts: What advantage do dogs have in clearly disclosing whether they are afraid or unafraid in a conflict?

texts:
Dogs are known to clearly show whether they are afraid or unafraid with the posture of their tails during a conflict.

How and why is this beneficial?

My limited understanding makes me feel that, in any social setting, disclosing whether an actor is afraid or unafraid would almost always be unfavourable for the actor. Is this incorrect?

Isn't it better for the less confident dog to try to bark out the stronger one and if it doesn't work then simply walk away, rather than broadcast that it is afraid of the stronger dog?


texts:
I need some figures on the pressure humans are capable blowing with their mouth with zero flow. I only need very approximate figures. I'm guessing around 500mm of water? I haven't got a tube handy to try it out.

I've heard that it can also cause damage, eg playing wind instruments has been show to increase health risks due to inter-occular pressure. Any figures on what an acceptable level would be for someone repeatedly blowing for a profession?


texts: Why are certain cells more likely to be attacked in autoimmune conditions?

texts:
For example, type 1 diabetes occurs when the immune system attacks and kills beta cells in the pancreas. This is relatively common.
What makes beta cells more likely to be targeted than, say, alpha cells in the pancreas?


texts: Identify a small spider from southern Poland / eastern Europe

texts:
Can anyone identify this spider that I have just found in my home?

Details:

location: Katowice, Upper Silesia, southern Poland, eastern Europe (46.42 N, 17.78 E),
size: ~3-3.5 cm (from tip of one leg to tip of opposite leg) / < 1 cm (corpse lenght),
date: July 23th, 2020 (summer, approx. 10:30 am).


texts: How can I determine the sex of a tree seedling?

texts:
I would like to plant some home grown female mulberry trees in a circle, with a male plant in the center for pollination. How do I determine the gender of a tree seedling? I know it's possible, because I've seen mulberry trees labeled as 'male or 'female' at nurseries. Do I need special equipment?

I've seen the related question: Can you tell the sex of a white willow when it's not flowering?


texts: What are the coverings of femoral hernia?

texts: It was my Viva question and I was really puzzled.I know what is femoral hernia and it route like the abdominal content moves down the femoral canal and further through the saphenous opening and all but I have no idea about it's coverings.Can anyone please help me


texts: Can only fully matured sperm fertilize an egg?

texts: Are only mature sperm able to fertilize an egg? If so, is there typically a reserve of mature sperm that are saved after an ejaculation or does a male need to wait for new sperm to mature before trying to fertilize an egg again? In humans it seems that the the shortest maturity period for sperm is around 42 days (New Findings on Sperm Life Cycle Could Impact Fertility Treatments). Do the new immature sperm serve any purpose after ejaculation?


texts: Why are vegetables either red or yellow?

texts:
Have you ever wondered why these two colors occur so often? Take these:
onion
waltnut
potato
carrot/parsley
and even cabbage which can be green or red.

Why these two pigments? Or is it just one pigment and it's just its concentration that makes the difference?

Thanks for any explanations!


texts: What is the distinction between the terms detrivores, decomposers, saprotrophs and saprozoic organisms?

texts: All of them feed on dead and decaying matter (detritus). Detrivores and decomposers are distinct, as it says on Wikipedia, in the fact detrivores consume macroscopic clumps of detritus while decomposers metabolise detritus on a microscopic scale. Are detrivores and decomposers both types of saprotrophs? Also, what exactly does the term "saprozoic" mean, and how is it distinct from saprotroph and decomposer?


texts: Can mammals and/or birds see / detect infra-red light?

texts: Wondering if there is any evidence that mammals or birds eyes can detect light emitted in the infra-red?  The reason I'm asking relates to the use of nest cameras to detect predators, using infra red LED light to take pictures at night.  New technology allows a picture to be taken every 3 seconds, throughout the night.   Clearly if these can be seen - then a mammal, or nocturnal bird could quickly learn to look for the flashes of light and find a tasty source of food...


texts: What would be required to evolve an animal (non-human) brain to obtain human-level cognition?

texts: Could any animal subject to the right conditions evolve human-level intelligence? Suppose that an artificial intelligence (AI) decided to artificially evolve a population of octopus (don't ask why, its for science) by restricting them to calculated environmental pressures, and over millions of years, the AI manages to produce a relative of the octopus that has a similar level of cognition to humans. Is this possible? If it is possible, what are some steps (in general) that might be required to evolve a complex animal brain (to human-level cognition or beyond)?


texts: Technical term for water entering a semipermeable membrane?

texts:
Would the word happen to be diffuse? I have tried imbibtion but that word is invalid because it isn't specific to osmosis.

Research: http://www.majordifferences.com/2013/12/difference-between-osmosis-and.html#.V9xc4fkrLIU


texts: What are these black masses floating on my pool?

texts:
I've been cleaning them for some time. At first I thought it was some kind of synthetic material, but when I took one with my fingers it disintegrated into filaments. I placed another under my usb microscope and they appear to be an aggregate of green tubular bodies.

They grow (appear) from one day to another, only 1-2mm diameter. My best guess is that they are some kind of algae, but I'm lost to find exactly what. I live in the south of Spain, the pool is treated with chlorine, in a well illuminated zone. There are no other algae growing, and the area is urbanized.


texts: I work in the PV industry and was asked a question recently during a presentation. Could Bioluminescence provide enough light to power a PV array during off peak hours? I understand the PV portion and the light spectrums needed to power the photovoltaics, but I have no clue how the science of Bioluminescence works or what type of light is emitted. I have the suspicion that this may be theoretically possible, but would require too much raw material? Any insight would be appreciated.


texts:
During the process of Conversion to Ribonucleoside Monophosphates the various ribonucleoside triphosphates break off their high energy bonds after linkage to the DNA.But the first ribonucleotide triphosphate retains all the phosphates thus chemically distinct from the rest.

Now my question is:
Why does it retain the phosphates?


texts: Calibrating Motic Camera to Stage Micrometer

texts:
Whilst calibrating my Motic Microsope's camera, I am able to calibrate the 10x object lens against the stage micrometer accurately.  However when I calibrate (using the Motic 2.0 Plus software) the 40x object lens, it always sets the ratio incorrectly.

For example, in the calibration panel, I load a photo of the scale that I took and then I draw the circle so that it measures the pixels both in height and width and then I tell it that the circle is 10 µm.  But it doesn't seem to get the ratio correct.  When I did this for the 10x lens it worked perfectly.

So I took a photo of the scale with the 40x object lens and then went to calibrate that.

Here you can see how the calibration is performed: you position a circle over the photograph and tell it the size in µm (it's rather large, sorry):

Here you can see the measuring line out of whack.  It gives me 8 µm for a length that should only be 4 µm.

Am I missing something?


texts: Why are there few tetrapod dinosaur carnivores?

texts:
Today, most big carnivores are quadrupeds. Bears, Tigers, wolves.

During the Jurassic and the Cretaceous, carnivores were mostly bipedal, dinosaurs mostly from the Therapod family.

Why was bipedalism previously a very efficient predator mode for dinosaurs, when evolution could have made some quadruped familes, at least for the 10-400 kilo carnivores? For the Paleogene, there were briefly terror birds, and since then all the major carnivore families have been quadrupeds, and mammals have not evolved dinosaur convergeant evolution towards Therapod body formats. Why not?


texts: Derivation of discrete replicator dynamics

texts:
Related: Discrete vs Continuous Replicator Dynamics

I am trying to perform a derivation of the discrete time replicator dynamics, but I am unable to get through Cressman's derivation in "Evolutionary Dynamics and Extensive form games" on page 21

Basic notations:

$S = \{e_1, \ldots, e_n\}$ are pure strategies

$\pi(e_i, e_j)$ payoff of player using strategy $e_i$ versus strategy $e_j$

$p \in \Delta^n = \{(p_1, \ldots, p_n) | p_i \geq 0, \sum_i p_i = 1\}$ mixed strategy

$\pi(p, \hat p) = p \cdot A\hat p = \sum\limits_{i,j = 1}^n p_i a_{ij} \hat p_j$ is the payoff of strategy $p$ versus $\hat p$

Derivation of the discrete replicator dynamic:

Let $n_i$ be the number of individuals using $e_i$ at generation $t$.

Then $n_i' = n_i (e_i \cdot Ap)$ be the expected number of individuals at generation $t+1$

Let $p_i = \dfrac{n_i}{\sum_j n_j}$ and $p'_i = n_ie_i \cdot \dfrac{Ap}{\sum\limits_j n_j e_j} \cdot Ap = (\sum_j n_j)p_ie_i \cdot \dfrac{Ap}{\sum\limits_j n_j}\sum_j p_je_j \cdot Ap = p_i(e_i \cdot \dfrac{Ap}{p}\cdot Ap)$

Then the standard discrete time replicator dynamic is
$p'_i = p_i \dfrac{e_i \cdot Ap}{p\cdot Ap}$

Questions: There are numerous moving parts in this derivation and little explanation as to where each item came about

Just to make sure, $n_i' = n_i(t+1)$ right?
Why is that $n_i' = n_i (e_i \cdot Ap)$ is the expected number of individuals at the next generation? This is just the number of individuals at the current generation times the payoff to pure strategy $e_i$, is there a derivation for $n_i'$?
I understand $p_i$ is the fraction of players using $i$ versus all the other strategies. But can someone explain how $p_i'$ came about, where are all its pieces? I am especially confused about the part where it says $Ap/p$, because $p$ is a vector and you can't divide it...
Is there another derivation of the discrete time replicator dynamic?

Any help is appreciated.


texts: What bug is this? I found several in my flat and I have no idea

texts: what kind of insect  is this? is it a moth larvea or a carpet bug?


texts: Circulating Tumor Cell vs Circulating Tumor DNA

texts:
I'm a little confused about the wording of these two phrases and under which context the epithelial-mesenchymal transition occurs.

For example:

Is it the circulating tumor cell that releases the ctDNA so that it undergoes EMT?

Or

ctDNA from the CTC somehow creating new instructions for the EMT phenomenon to occur?

I think there is something I am fundamentally confused about and or I am mixing several or different concepts and phenomenon together and would like to get some clarification on this.
Thanks.

EDIT: So this is my new hypothesis / thinking..

So when EMT occurs, CTCs are more likely to develop in the context of cancer, and so when CTCs circulates throughout the blood stream CTCs may be apoptosed of necrosed as a by-product thus leaving ctDNA in the bloodstream and or possibly through out the body.

Is that a correct explanation to my confusion?


texts: What is the scientific name of this lovely orange black flying beetle?

texts: Found on Rangoon creeper (Combretum indicum)


texts: Can a novel protein domain arise de novo in nature or did all protein domains evolve from a single ancestor?

texts:
I know there is extensive research into the taxonomy and evolution of protein domains and many connections are, and are continuing to be, found between numerous domains. However, as far as I can see, new domains always arise from preexisting ones. I have seen no paper, in any field, showing the development of a new protein domain from a random piece of DNA which just mutates a start codon and synthesizes a new protein with no apparent function. I know this is theoretically possible but has anyone seen any evidence it has happened in any form of life in any geological period of time? OR are there some other mechanisms that could generate novel domains from non-coding DNA that I have overlooked when searching the journals?

My thinking is that, if de novo protein domain generation doesn't occurr, does it mean that all protein domains are a kind of "progeny" of a single domain that arose at the onset of life as we know it (or maybe even was the first lifeform on Earth). It seems very strange to me that this hasn't been pointed out by now since it's a relatively simple deduction. Thus, I'm asking either for a reference paper showing evidence for the evolution of de novo protein domains from a random piece of DNA that somehow managed to turn into a gene or for a reference to a paper discussing the idea that all proteins originate from a common ancestor existing at the onset of life and even, possibly, a single domain as old as life itself?


texts: What is the relationship between sexual and natural selection?

texts:
In Evolutionary ecology: Novelty makes the heart grow fonder, they say:

  Thus, it seems that the diverse coloration in this species is promoted by both natural and sexual selection.

I had always thought of sexual selection as a subset of natural selection. What's the right way to think about the relationship between the two?


texts: How is saltatory conduction faster than conduction of unmyelinated fibers?

texts:
It's always the same explanation that currents are able to "hop" along Ranvier nodes instead of passing continuously along the axon making saltatory conduction more efficient than continuous conduction.

However, if we take this down to the molecular level, I cannot understand how they are different. Conduction in unmyelinated nerve fibers are first triggered by an effective stimulus, changing the cell membrane potential and thus opening the voltage gated sodium channels, causing an explosive influx of sodium ions. The action potential is conducted along the fiber through stimulating sodium channels in nearby regions, causing rapid flow of sodium ions into the cell in membrane immediately near the segment of stimulation and this process repeats as the action potential passes unidirectionally along the axon.

Conduction in myelinated nerve fibers are usually described as hopping along the axon, but on the molecular basis, sodium channels are congregated at the site of Ranvier nodes, large numbers of sodium ions that made its way into the cell swim down the axon in the cytoplasma of the nerve fiber reaching the next ranvier node, changing the membrane potential in that specific site therefore triggering another influx of sodium ions.

So to put the question simply, the mechanism of continuous conduction is triggering voltage gated sodium channels continuously along the way, whereas the mechanism of saltatory conduction is triggering-swimming-triggering-swimming...how does this difference essentially make saltatory conduction faster?


texts: Of these three words, perhaps Neurotransmitter is the most obvious. I took a look at Wikipedia page for Neuromodulation and found that this is pretty similar to Neurotransmitter too. I guess Neuromediator is somewhat more broad. Could someone clarify these nomenclature for me?


texts: is this true to select 100 volume higher concentration of a drug test?

texts:
I am interested in knowing how to find/optimise the concentration needed for a drug effect in cell. and different organism

For example, if I use 1 micro molar for treating a cell. Should I use 10 nM when I use C.elegant ? how do you define or tune such a concentration ? Please give me reference too if there is any


texts: What are the mechanism binding histone code with alternative splicing?

texts: There are some bioinformatical considerations showing that there is a significant correlation of some between histone code and alternative splicing; but what are the hypothesis about the underlying mechanisms? Is there any experimental insight in the problem?


texts: Can plants yield two more molecules of ATP from glycolysis?

texts:
Since 2 ATP are used to convert glucose to glyceraldehyde 3-phosphate in glycolysis, can plants bypass this step of ATP investment since they produce glyceraldehyde 3-phosphate directly from the Calvin cycle?

If yes,  what would be the final yield of ATP.

If not,  why not?


texts:
Is there any relationship between heartbeat rate and life span of an animal?

Do they belong to a cause-and-effect relationship or are they both caused by some phenomenons or a common cause?


texts: Lysozyme amino acid sequence: N-terminal extension

texts:
I looked up the amino acid sequence of lysozyme here: http://www.biology-pages.info/L/Lysozyme.html

Then I crossed referenced that with the lysozyme sequence on UniProt: https://www.uniprot.org/uniprot/B8YK79

My question is why does the sequence on UniProt start with eighteen other amino acids before getting to the start of the sequence described in the first source?

The sequence on UniProt starts with "MRSLLILVLCFLPLAALG".  I know the M comes from the start codon in the gene for the protein, but where does the rest of this come from?


texts: Why does vinegar made from wine contain only about half as much acid as the original alcohol?

texts: It is my understanding that the fermenting bacteria process the alcohol into acetic acid. But why is it about half the percentage of volume? For example table wine is often 12% ethanol, but vinegar is generally about 5% acetic acid.


texts: At what rate does synaptogenesis occur in adults?

texts:
From many articles, I can find the rate of synaptogenesis at its highest: roughly 580,000/minute (weeks 6-23 after conception). However, I'm having trouble finding the rate with which it occurs in adults. I find articles stating that it is higher in areas like the hippocampus than other areas and depends on things like exercise and stimulation, but no numbers.

What is the rate of synaptogenesis in a adult brain?


texts: Is feeding birds only after a snowstorm helpful or harmful?

texts:
We had a very rare snowstorm here which left the ground covered in 8" of snow and trees covered in snow and ice. It'll likely all melt away in the coming days as we have sunny days and temps rise above freezing.

I noticed some birds poking around the snow on my back deck, so I cut up some raw untoasted walnuts and almonds into small pieces and and scattered them out on the deck and have seen a number of small birds stopping by to feed.

I travel away from home a lot and can't reliably keep a bird feeder stocked, so I'm wondering if this temporary food source is helpful or harmful to the birds since I'm not going to keep it up after the snow melts.

My concern about harm is about causing them to change their behavior and training them to keep looking for food on my deck after I stop feeding them in a few days. I'm assuming that the raw nuts I'm feeding them won't cause any harm even if it's not a well balanced diet, but I don't really have anything more suitable.

I don't know what type of birds they are, they are around 3" high, typical Pacific Northwest birds, I guess.


texts: My hand was stabbed with a pencil tip 10 years ago - why is the graphite still visible?

texts:
I, and multiple people that I know, have permanent marks (up to 30 years) from a graphite pencil puncturing the skin. The palm of my hand still shows a very clear mark where my hand was punctured by a pencil 10 years ago in school.

Why/how does the graphite remain in the skin indefinitely?


texts:
Are there multicellular isogamous species?

Seeking through the examples of wikipedia I would tend to think that there are no multicellular isogamous species.


texts: Is intelligence (or mental ability) genetically transferred (inherited characteristic) from the parent to the offspring or is it an acquired trait?

texts:
The question is simple- whether our mental ability i.e. ability to acquire and store knowledge and comprehend and analyse the stored bits, an inherited trait (i.e. genetically transmitted from the parent to the offspring) or is it an acquired trait (depends on environmental, social factors)?

P.S. - Please attach the link of any reference/research (if any) with your answer.


texts: How does a nerve cell adjust if O2 diffusion is interrupted?

texts:
What effects would it have on a nerve if the oxygen supply is cut off? Is there any data on this?

Does the nerve conductance velocity increase? What about the Amplitude and receptor-channels on/in the nerve?

Funnily enough it's insanely hard to come by an answer to this question, or maybe I'm just searching at the wrong places....


texts: How do afferent mechanoreceptors work on the finger pads?

texts:
I'm having some difficulty understanding how the afferent signals are sensed in the finger pads. My understanding is that for mechanoreceptors, as the indenting force increases, their effective response also increases. Additionally, as contact area increases, so does the overall stimulus area and hence a larger response amplitude from the mechanoreceptor afferents should be found.

However, the results shown in this article in the Journal of Neuroscience that discusses this physiology shows contradicting results. In this article, the closer the dot spacing (1 mm or less) and the higher the contact area the lesser the receptors seem to fire, and stop firing altogether at about 1 mm dot spacing?

Why would this occur?


texts: hummingbird feeders - is sugar water healthy for them?

texts: The top results on google for DIY hummingbird feeder suggest a white-sugar solution for the feed.  In humans we make a big deal about processed sugar vs. the sugar you get from, say, eating a piece of fruit.  Does this matter for hummingbirds?  Their metabolisms so high, it makes me wonder if this is relevant.  Maybe it is not!  But I would like to know.


texts: Are stroma lamellum and grannum lamellum the same?

texts: I have a picture in my textbook that is confusing me as to how they are different.I tried looking for some info on the internet, but could'nt get it clear.Please help me.


texts: How body loses more fat in CO2 form than in sweating form?

texts:
Yesterday, I saw TV Game Show.

There is question like this: Body loses more fat in which form?
It gave 4 options:

1) CO2

2) sweating

3) xxx

4) xyz

sorry i didn't remember 3 & 4 options.
so right answer is CO2. anchor explaining the reason behind it, suddenly my brother switch the channel. all gone.....

Everybody thinks sweating is right answer, i have reason for it, if we work out our body whole fat comes out in sweating form.


texts: What's the difference between diuretic veggies and alcohol that make the latter bad?

texts:
So I'm reading this article to Treat Fluid Retention and it suggests

Eat foods with diuretic properties.

But also

Avoid drinks that will dehydrate the body such as tea, coffee and alcohol.

As I understand, tea, coffee and alcohol are plenty diuretic. So what makes those veggies's diuretic nature better than alcohol's?

I know alcohol is more harmful than veggies, but I mainly wanted to know how do diuretic veggies help you when infact the diuretic alcohol actually makes you dehyderated? How's veggies' diuretic nature more helpful than the alcohol's (disregarding other side-effects of it)?


texts: Can we use Acetyl Phosphate instead of Acetyl CoA in TCA?

texts:
I am thinking Citric Acid cycle and activation of the end parts of Acetyl and alfa-ketoglutarate.
Let's consider only now Acetyl to make things simpler.

I have tried to explain the thing by symmetry - phosphate tetrahedral, while coenzyme A seems to be mostly some V shaped.
However, it does not help.

Can human body use Acetyl Phosphate instead of Acetyl CoA in TCA in some situations?

I know that you can activate acetyl-CoA again by phosphate:

acetyl-CoA + phosphate <-> CoA + acetyl phosphate


texts:
I am not a biology student, but just want to know if GULO gene are present only in mammals or all species possess it ?

And is GULO gene active in human fetus?


texts: Why are some menstrual cycles irregular?

texts:
A friend of mine asked me this today, and I didn't know. I remember studying the menstrual cycle a few years ago, but I can't remember the details (other than it was very hormone-related), and so I don't have a good base in the matter anyhow.

What makes some women have irregular periods? Why?


texts:
I’ve seen tyrosine classified as a hydrophobic amino acid due to its aromatic ring in some textbooks and as hydrophilic due to its hydroxyl group in other textbooks.
How does tyrosine actually function in a peptide under physiological conditions (aqueous polar medium and pH~7)?


texts: How does pressure travel through the cochlea exactly?

texts:
I cannot find this answer anywhere.
What I do know is that the stapes pounds on the round window of the cochlea and this causes the fluid to move inside the cochlea itself, which has the three chambers (the scala vestibuli, the scala media, and the scala tympani), where the basilar membrane between the scala media and scala tympani is what fluctuates with pressure. This leads to the sound processing in the scala media and the organ of Corti due to the shearing motion of the hair cells against the tectorial membrane, and so on and so forth.
But I don't understand the pathway of the pressure. A lot of resources show the pressure wave moving front-to-back (towards the apex), making the basilar membrane move simultaneously. But at the same time, they also show that the full pathway through the cochlea goes front-to-back through the scala vestibuli, turns around at the apex, and then goes back-to-front through the scala tympani where the basilar membrane is located. So how can the basilar membrane be moving front-to-back when it's stretching along the latter half of this cochlear pathway, way over on the other side of the scala media?
Therefore I am unclear if (1), (2), or both of the following are true:
(1): Does the pressure somehow permeate through Reissner's membrane (between the scala vestibuli and scala media), move through the scala media (without disturbing any hairs in the organ of Corti), and then push on the basilar membrane from above, which would allow for this front-to-back wave motion?
(2): Does the pressure move the basilar membrane from below during its "return trip" going back-to-front through the scala tympani?


texts: Cnidarian life cycle, a case of ontogenetic polymorphism?

texts:
Cnidarians have a complex life cycle which usually goes as follows:

Egg hatches larva.
Larva settles on sea bottom and transforms into a sessile polyps.
Polyps undergoes strobilation and asexually buds off juvenile, free-swimming medusae.
Medusae eventually mature and reproduce sexually to beget new eggs.

Given the morphological and physiological disparity between the three forms (larva, polyps, medusa), and how each form comprises a distinct stage in the cnidarian's development (i.e. ontogeny), would it be accurate to say that the cnidarian life cycle is an example of "ontogenic polymorphism"?


texts: Would the human body react faster to touch or sight

texts:
I am currently working on an assignment for my physics class, but I believe my question is biology related.

For a two person lab, I am trying to time how long it takes a tennis ball to fall two meters, Using basic physics equations I was able to determine that the ball should take around 0.66 seconds to hit the ground but my results are generally very off.

Would I be able to react faster if I were to stop the timer when I felt the ball hit my other hand, or would I have a worse reaction time than if I were to use my current method of stopping the timer when I see/hear the ball hit the ground.


texts: Rubbery Orange and Fuzzy Mould From Bread

texts:
So I share a house, and my other housemates are currently away. One of them had some "plain" bread (a popular type in Scotland), complained a piece had mould on it, and so I had assumed they'd thrown the rest away before they left.

So you can imagine my bemusement when I decided I wanted some toast, opened the bread bin and was greeted by this:

You can just about see where my housemate's bread was, in the red packet on the left under the mass of orange and fuzz. The loaf in front was unopened, but the packaging was just so covered in this stuff I had to throw it away.

Now I didn't think to take any more pictures, as my priority was getting rid of this, on which I may have gone overboard (if I'd had a flamethrower I'd have used it) so there's no trace left. I only became curious later, but looking around on articles about bread mould I haven't found anything whose description seems to match what I'm seeing; in fact most are just describing the usual blue/grey mouldy patches seen on the bread itself, and none of the pictures I've found show anything that looks like this, the worst showed a piece of bread entirely blue/grey with a few millimetres of fuzz on it. Articles on orange mould seemed focused on the type that can appear on grout and such, and wasn't immediately identifiable as being the same thing.

The fuzzy parts appeared fine like concentrated spiderwebs, while the orange stuff was somewhat rubbery, or at least the bits left stuck to the plastic bread bin after I got rid of the worst of it. Also of note is that there was a lot of something, presumably spores, when I opened the bread bin, or maybe just the spider-web like stuff disintegrating; fortunately I wasn't breathing in at the time. This stuff has grown quickly as well, though I expect the mouldy bread must have been bad when my housemates left, this orange/fuzzy stuff has exploded out over only about two or three days.

Anyway, I'm curious, is this just some normal progression of the common penicillium variety, or is it something else? Is the orange the natural colour, or has it leached colour from the wasted loaf's packaging?

Apologies for being a bit imprecise, my scientific background is in computers, and the scientist part of my degree really just means I'm a programer.


texts: Do all mushrooms have the same multicellular ancestor? Did that ancestor feature common mushroom elements such as cap, stem, sporofore, vulva, bulb, etc.


texts: Indirect pathway of movement and Parkinson's?

texts:
So Parkinson's disease leads to the loss of dopaminergic neurons. I understand how the direct pathway (an excitatory pathway) is inhibited, leading to a loss of movement. However, how can the loss of dopamine neurons cause enhancement of the indirect pathway (which enhances its inhibitory effect, leading to a loss of movement)?

I assumed that loss of neurons would decrease stimulation of both pathways.


texts: Is there a genomic code for nucleosome positioning?

texts: What does a genomic code for nucleosome positioning in eukaryotes actually mean? By the code is it right to think that specific DNA sequences favour nucleosomes and others don't? I see that there for and against arguments on this topic. What is the current view on this topic?


texts: How can cane sugar sucrose be different from beet sugar in regard to carbon-13 content?

texts:
According to an article in SCIENZA IN CUCINA, by Dario Bressanini, le Scienze Blog content of $^{13}C$ differs in sucrose in beet sugar compared to cane sugar. What is this due to? Are there any similar examples?
Is the difference in synthesis enough to explain the difference?
One could guess that the weight of the carbon molecule is more critical in one of the synthesis chains.


texts: Does arterial blood always flow away from the heart?

texts:
Is there a negative net flow of blood in human arteries at any point of the cardiac cycle? I realise that blood flow can be turbulent, e.g. in the aorta or around stenotic arteries, but then the average is still flowing away from the heart.

The question was provoked by this graph, which admittedly I haven't seen in its context:

A similar graph showed negative velocities in the aorta and innominate artery of humans.


texts: Rank-specific rules for taxonomic classification

texts: There appears to be a very specific (although not universally agreed) list of characteristics that describe what a "species" is--and the list applies to ALL species.  Are there similar generic rules or characteristics for the other taxonomic ranks that do not resort to characteristics of existing members of the rank? For example, I've seen "number of lobes on leaves" used to place a particular flower in a particular Family or Order.  Is there anything that applies across ALL Families, or across ALL Orders, etc., of the tree of life?


texts: What is the meaning of multicellularity?

texts:
I can't understand what multicellularity is. Wikipedia states that any organism having many cells is multicellular. By this definition bacteria can also be multicellular. For example, cyanobacteria can form filaments made up of specialised cells like spore cells and vegetative cells.

But aren't bacteria supposed to be unicellular only? I would appreciate it if someone could clear up my confusion.


texts: Why does the stability of YAC increase with size?

texts:
From Lehninger Principles of Biochemistry :

  The stability of YAC increases with size (up to a limit). Those with
  inserts of less than 100000 are gradually lost during mitosis.

Why does this happen ? (YAC refers to yeast artificial chromosome )


texts: Is it possible to correctly identify presence of Y chromosome with external physical test only?

texts:
I asked a question related to the third sex, and I came to know that its always possible to categorize a human to male or female with presence of Y chromosome.

Now, I have another question. Is there a way to say if someone has Y chromosome only with external physical test? More specifically:

Someone has a penis, can we say that s/he will have Y chromosome?
Some one has Y chromosome, can we say that he will have a penis?


texts: Technical reason that specialized embryonic cells form

texts:
During the embryonic stage of human development, rapid cell division occurs and specialized cells form to build the various parts of the developing fetus.

I'm curious:

Why technically do specialized cells (such as brain cells) form?  I suspect this is due to a DNA sequence, but why chemically / mechanically should a genetic combination cause a certain specialized cell-type to form?
Have we (the international scientific community) reproduced the fundamental chemistry that causes any specialized cell-types to form?


texts: What happens when you cook tree spinach with aluminum?

texts: The Internet is filled with warnings that you shouldn't cook tree spinach(Cnidoscolus aconitifolius) in aluminum, because it will react and create toxins that cause explosive diarrhea when consumed. However, I can't find anything more specific than that. Does something (presumably hydrocyanic acid(HCN)) from tree spinach react with aluminum? If so, how does the resulting product cause diarrhea?


texts: books for beginners in research in mathematical biology

texts:
I am a M.SC(mathematics) student. I have no subject like mathematically modelling.But  i'm interesting in research in mathematical biology.Initially which book i should study.
Please guide me.THANKS...


texts: Phenol Red Broth question; what is point of broth without carbohydrate?

texts: Without carbohydrate in the broth (some) bacteria would then degrade the peptone, which from its end products would increase pH and then turn zhe phenol red pink. So I think this is some type of control just to make sure the test parameters can produce a pink broth. Is there something more here that I'm missing though? The question is asking what function phenol red broth without carbs serves, and that's only thing I can think of. Is this correct or is there something else that is more relevant?


texts: Is there a cellular mechanism that detects Ribosomal damage?

texts:
What kinds of options, if any, do cells (Eukary and Prokary) have for detecting, and repairing damage in Ribosomes (of all types)? I am curious as to
what happens when a cell sustains damage of some form, such as radiation, and the Ribosomes are damaged.


texts: How do we know that ammonites are a kind of cephalopod rather than another type of mollusc?

texts:
On a recent fossil hunting trip, I found a small fossil that an expert identified for me as an ammonite beak. He told me such fossils are not uncommon, but are not normally found with their parent shell due to the decay of the soft tissues holding the beak in place.

I know that under some unusual conditions, (i.e. the Burgess Shale) the soft tissues of animals can be preserved. And a quick google search reveals that there are rare belemnite fossils with their tentacles in place.

However I can find no reference to any ammonite fossils, nor any of the orthocone clades, with soft part preservation.

Shells of similar shape and structure are not unknown in other groups of mollusic (i.e gastropods). So: what characteristics of the shell make taxonomists sure that ammonites and orthocones are cephalopods rather than some other kind of mollusc?


texts: Can skin be removed and replaced so that it maintains its original cellular structure?

texts:
The cells in our body that form tissue, such as our skin, are interconnected. I would think that cutting out tissue or trying to repair/replace it, as is done in surgery, or after an injury, could not be accomplished without damaging this network and creating irreparable damage.

Am I mistaken and is it possible to remove and replace skin, close a wound without damaging the underlying cellular structure and having scar tissue form?

When it is healing, is the tissue that is healing in some way weaker than the tissue that remained intact, say just beyond the margin of the wound?

If someone has surgery, can their skin be repaired completely with the proper amount of healing time?


texts: Why does cutaneous respiration need moist skin?

texts:
My teacher told me the other week, that respiration through skin (cutaneous respiration) cannot happen without moist skin. That is why frogs have moist skin.

My question- Why does cutaneous respiration needs moist skin? Can't it happen on dry skin?

ALSO - Why does cutaneous respiration happen in the first place? It uses diffusion right? And diffusion doesn't produce enough energy for an organism as big as a frog to live does it?

Please help.


texts: What species of ant is this, and is it a queen?

texts:
I found her underneath a big rock along with a bunch of much smaller Lasius niger workers, so
I suspect it might be a queen. I know Lasius niger doesn't have soldiers, so what could it have been doing there if it wasn't their queen? Also, sorry for the bad picture quality, I couldn't find a better camera, and also don't have a proper magnifying glass.

Country: Belgium

Environment: forest

Location: underneath big rock

Behaviour: calm when walking in lighted up areas

Species it was found with: Lasius niger workers running around frantically (note: this specimen was much bigger than the workers)


texts: Prediction of transmembrane beta barrels?

texts:
I studied that prediction of transmembrane alpha helices is more easy and accurate and also good algorithms are available for their prediction. But when we move towards prediction of transmembrane beta barrels (cylindrical structure composed of anti parallel beta-sheets) then for their prediction only a small number of algorithms are present which also don't give reliable results.

My query is that Why it so? Why the prediction of transmembrane beta barrels is difficult and why developers can't develop reliable algorithms for this purpose?


texts: What is affinity isolated peptides??(I have not studied biology since last 8 years and now I am going through it because I need it for my research. So if someone can describe it in simple language it would be very helpful)


texts: This presentation on anaerobic digestion mentions (pg. 19) two major pathways for the digestion of amino acids: Stickland reaction and reductive deamination. While I find some info on the former, what is reductive deamination? What is a representative reaction and what partners are needed?


texts: What prevent us from synthesizing a cell from "scratch"?

texts: In this recent article "Design and synthesis of a minimal bacterial genome", they created a minimal cell with only 473 genes. However, they didn't synthesize all of the necessary components of the cell to get going. How much of those extra stuff can we currently synthesize, and what are the ones that we can't synthesize in the lab to create a working cell from scratch?


texts: Unidentified insect seen in southern UK, near North Downs

texts:
This creature was seen in southern UK, near North Downs, just this weekend.
https://youtu.be/5VJYOrMJXaQ


texts: Can (or have) antiviral drugs created drug-resistant viruses?

texts:
Evolution/emergence of antibiotic-resistance in bacteria is a known effect of extensive use of pharmaceutical antibiotics.

Pharmaceutical antivirals have come into extensive use in recent decades – e.g., Tamiflu for influenza; Harvoni for hepatitis C; Valtrex for herpes.  Some are even prescribed as ongoing "suppressants."

Has anything analogous to antibiotic resistance (i.e., antiviral resistance) been observed in viruses treated with pharmaceutical antivirals?  If not, are there theoretical reasons this would be unlikely (or impossible) to occur?


texts:
While tracing dendrites on EyeWire I encountered the following situation. They belong to an Orientation Selective Ganglion Cell.

It's the first dendrite I've noticed with such a clear 'hole' in it, though which another dendrite passes.

Is it possible for one dendrite to pass through another? Perhaps I shouldn't have 'connected' the top part with the bottom part?


texts: I’ve been juicing some ginger by grating it and pressing it (by hand). A white residue collects at the bottom of the liquid. What is this?


texts:
What is in compound "Brazzein" that it makes it 2000 times more sweeter than sugar?
Can anyone please explain the science behind it?


texts: What are the roles of guanidine-HCl and ethanol in binding of DNA to silica?

texts:
I'm trying to understand how exactly the binding to silica gel (in kits) step works and I cannot find any papers which provide an explanation of the physics or chemistry; especially on the way that Guanidine-HCl works.

So lets get them from the beginning.

First of all, we adjust DNA binding conditions by adding a buffer which includes
Guanidine-HCl and ethanol and then we centrifuge our sample. I knew that Guanidine-HCl destroys the tertiary structure of proteins but somewhere I read that also it helps the DNA to bind to a silica column. I searched to find the way that it works but I couldn't find a paper. Also what is the role of ethanol in this step? Is it just to remove proteins and polysaccharides from the sample?


texts: What is this creature I found on my house?

texts:
What is this creature and what species is this?

I found this on my balcony.


texts: Why don't housekeeping genes have TATA Box regions in their promoter sequences?

texts:
Housekeeping genes are genes that are continuously transcribed. Like all other genes they have promoter sequences, but they don't have TATA box sequences that are used to specify from where transcription is going to begin.

Why don't housekeeping genes have a TATA Box in their promoter sequences?


texts: Under which circumstances does muscle hyperplasia happen in humans?

texts:
What circumstances allow humans to have muscle hyperplasia in the prenatal and immediately postnatal period that doesn't exist later?

Is it about specific hormones that follow through our veins?


texts: is there a constant leakage current across axon even in absence of stimuli?

texts: because of resting potential is their a constant leakage current across membrane due to resistance of membrane and ion pumps continuously pump restore the resting potential ?


texts: Debug Fresno; why are the released mosquitos said to be sterile?

texts:
I saw in the news that Verily Life Sciences will participate in an experimental release of sterile male aedes aegypti mosquitos in Fresno, California. Aedes aegypti is considered an invasive species in California, and can be a vector for human disease including dengue fever, zika, and chikungunya (according to the video). See the Verily blog Debug Fresno, our first U.S. field study and/or the attached YouTube video Introducing Debug Fresno.
The released male mosquitos will carry a bacterium called wolbachia, which when transferred to the female during mating will prevent eggs laid by the female from hatching. Wobachia presence, parasitism and mutualism with insects is widespread, and Wikipedia's article on it even includes a section on applications to human-related infections.
Question: Are the males said to be sterile because of the bacteria which results in nonviable eggs, or are they also incidentally sterile in addition to being vectors for the wolbachia bacteria (and eggs were presumably fertilized by other matings)?


texts: Who created the codon wheel chart (not as a table)

texts:
I'm trying to find out who created or first used the codon wheel chart as far as we can know?
(I don't mean the tabular format)


texts: Webtool to design guide RNA (gRNA) for use with CRISPR-AsCpf1?

texts:
My goals are to use a free webtool to:

Identify guide RNAs (direct-repeat sequence followed by the targeting sequence) appropriate for use with AsCpf1 in order to target a specific segment of genomic DNA.
Estimate efficiency and specificity of using the guide RNAs identified by the tool.

Unfortunately, when I tried to do this using the CRISPOR tool, the "Job Status" never advanced past the "Waiting" stage, even after 10 minutes. Attached is a screenshot to show what I see.

Specifically, I used the following settings in my query:

I named my sequence:

Mm Acaca block2 from BLAT alignment

In "Step 1" I submitted this sequence:

aactaaatct ccagcatctc catccccttc ttaggtttat ttattttatg ggtatgagtg
tatgtccgtg caccacatgt gtgcctggtg tctaccaagg taagtagagg tatacaaacc
cttggaattg aattatccac catgccgtca ggtgctggga gcaaattcag gtcctctttt
agagcagcaa gtatttccag ccacttagtc acctctgcag ccccttattt tcacagtctt
gagacaagaa tctcactctt tagcccatat tggcctggaa ctttaggcag tcctgccgga
gtttcagact gctgggatga caggcctgac ccattacgtc cactaaggat ggtttccttt
cctgtgagct agcagcatgt agactccaca aggctcctgg ggaagtgttg ttatagtatg
ttatagtata gttgcgaaag gaaggttttc agaagatatg ggtattacga agaaattcta
tgtaaagttt cttttggatt ctctgtttgt atAGATCCAG CATGTCTGGC TTGCACCTAG
TAAAACAAGG TCGAGACAGA AAGAAAATAG ACTCACAACG AGATTTCACT GTGGCTTCTC
CAGCAGAATT TGTTACTCGT TTTGGGGGAA ATAAAGTAAT TGAGAAGgta agttaaactt
actaaactat ttcgcttgaa gtatgtgaga tttcatgcct agatttgttg tttctgttca
aaaggatatt taggttttta gggactttgc ctttttatgc agggctatcc tttctgtctc
cctagcatgt tactaataca taatctcact gtgtacctgt gtttttacat

In "Step 2" I selected:

Mus musculus- Mouse- UCSC Dec. 2011 (GRCm38/mm10)...

In "Step 3" I selected:

TTTN-23bp - Cpf1 Acidaminococcus / Lachnospiracea

My questions are as follows:

Should I do anything differently to use the CRISPOR tool for my goals?
Are there other free webtools available for me to achieve the goals I outlined above?

UPDATE: I emailed the folks at CRISPOR, and they informed me the site had been down, but they have since restarted it. Hopefully, their restart is sufficient, but I will leave my question up with the hopes that others can point me to more webtools.


texts:
I don't know if this is a physics or a biology question but this might be better orientated around the element of how the human eye works in a 3D visual situation than physics.

Given the rise of 3D virtual reality headsets such as the Oculus Rift. I have a question about eye strain relating to these.

Often on a computer, eye strain comes from staring at the monitor for too long of which is the same continuous distance that your eyes have to focus on... thus causing computer vision syndrome (as well as lack of blinking). Meaning you should look at an object far away every X amount of minutes to rest the eyes.

How ever in a virtual headset, although the monitor is much closer, it is in 3D (or a fake 3D). So i wondered, does the eye muscles adjust based on this trick of fake 3D. Or will your eyes still focus on the fixed distance to the screen display regardless of the fake 3D perception, meaning you still get eye strain either way?

If you imagine looking through a 3D VR Headset, staring at a 3D object in the distance, is that going to create the same change in muscle adjustment in the eye as looking at a physical object in the real world of the same distance.

Essentially - 3D VR headsets could reduce the amount of eye strain. Because the eye is busy adjusting all the time for these "fake" distance illusions, rather than forced to focus in one way for a long length of time such as a 2D monitor. It might help people who struggle with computer vision syndrome perhaps?

Has any studies been done on this?


texts: Correlation brain size and muscle volume

texts:
I have 3 dogs that weigh ≈ 5 kg, ≈ 20 kg and ≈ 45 kg. The smallest dogs whole head would fit in the mouth of the biggest dog. Although I haven't measured it exactly but by just looking at the dogs I would expect the weight of their brain to approximately correspond to their body weight, that is the 20 kg dog's brain is 4 times heavier than the smallest dog and the 45 kg dog's brain is 10 times heavier.

Meanwhile, all three dogs seem to have similar intelligence.

What is all the extra weight of the brain of the bigger dogs used for?

You can expand this question and note that an average mouse brain weigh 0,5 g while an elephant weighs around 5 kg. Elephants might be smarter than a mouse but not 10 000 smarter. Besides, the brain of a human is much lighter than an elephant and we obviously are much smarter.

Why do bigger animals need bigger brains than smaller animals to accomplish approximately the same intelligence? Is it something along the lines that they have more muscle fibres and every single musle fibre needs a few neurons to control it?


texts: Explanation of ECG in MI using an electrostatic model

texts:
I found a paper presenting an electrostatic model to explain the ECG recorded in various leads. This model essentially calls for considering the depolarization wavefront to be the major contributing factor to the potential difference measured at the leads, especially the limb leads, by means of an aggregation of momentary dipoles with dipole moments organised according to the direction of propagation. It is also used in this book here, under the ECG section under Measurements of cardiac function.

The paper does not explain the observed ECG deformities in case of MI in detail. ST elevation, is a common finding in most MI cases. How do we explain this in light of the aforementioned model?

My thoughts

In the normal case, ST segment is isoelectric, as there is no depolarisation/repolarisation wavefront propagating. How is this isoelectric nature compromised in MI? Assuming most infarcts include muscle death or damage due to focal insufficiency of coronary circulation, even if a region of heart was dead, during the ST segment, the graph should show an isoelectric line (no deflection) as the living tissue will either be depolarised or polarised, (but not switching states) and the dead tissue will have either a completely obliterated membrane polarity or an altered polarity throughout the cardiac cycle. In any case, no part of the heart will be switching its polarity then. Why is then, some resultant dipole (which indicates a propagating wavefront of altering polarities)obsereved during the ST segment?

  alternative model
   To explain the elevation, this book (pg 522) provides a two cell model, and explains that the anoxic damage somehow
  causes the basal depolarised state of the cell to have a lower
  membrane potential difference, which causes all the segments of the
  ECG except the ST segment to be lowered, making the ST segment appear
  raised. I don't understand three things regarding this explanation.
  How will anoxic damage cause such a specific alteration in the polarity and the subsequent action potential? How can this two cell
  model be extrapolated to the whole heart with a focal infarct? How
  does this explanation be reconciled with the model presented at the
  head of the question?

Let me know if the question appears too broad and needs to be split, or if my assumptions are wrong in any way.

MI-Myocardial Infarction

PS:-  I seem to have lost the touch with the formatting on this site, and hence don't know which tags to use. Will take some time to get back :)


texts: When you take a very cold or hot bath how is that influencing your breath?

texts: It looks like when you take a cold shower or bath your veins get smaller and when you take hot shower your veins get wider. But is that right and do you need to breath more in both cases because you got less oxygen? If so how does it work in both cases?


texts: How much oxygen does a plant use up at night?

texts: Given the fact that plants cannot do photosynthesis at night but need respiration for their energy needs, they use up oxygen and generate carbon dioxide. But how much is this? If I fill a room with plants thoroughly, what composition will the air in this room be in the morning? Are different plant species vastly different in this regard?


texts: What is meant in biology by the term "evolved"?

texts: A student asked me this the other day and I thought that I would ask it again here. If one organism is said to be "more evolved" than another, what exactly does this mean?


texts: The average fecundity per woman varies a lot from country to country. I call average fecundity per woman the average number of born children per woman. In Homo sapiens, what was the average fecundity per woman during the paleolithic age for example? Is it about 2 offspring per woman or about 12 offsprings per woman?


texts: What is the scientific consensus on whether humans were monogamous during the period of evolutionary adaptedness?

texts:
The book The Mating Mind by Geoffrey Miller asserts, as part of its thesis, that humans were not monogamous in the environment of evolutionary adaptedness.

I found the book vivid and persuasive, but I'm interested in what others in the field would say. Is this the scientific consensus among evolutionary psychologists?


texts: How do you call the species that gives its name to a upper-level clade?

texts:
Just a silly question: I don't remember how the species giving its name to an upper-level clade is called.

e.g. the name of family Canidae derives from Canis lupus

You could say it is the "name-giving" species, but I'm certain a specific term exists.


texts: Why do plants store energy as carbohydrates and not as fats?

texts:
In my introductory biology class, we are learning about biomolecules. The textbook says fats are a more efficient energy store than carbohydrates.

So my question is - why would plants store their energy as carbohydrates and not as fats, if fats are a more efficient energy store?


texts: I am currently trying to start a research project, and this is the most important question that needs to be answered. I cant't move ahead without knowing the chemistry of the brain.


texts: Why do we find some things disgusting and others delicious?

texts:
For example, why do I love paprika while my girlfriend hates it? Why do I find broccoli disgusting and she adores it? As humans, there are things we'd all agree on being awful, like rotten meat, for obvious evolutionary reasons - those things are damaging to our body and we should not eat those. But when asked about delicious food, everyone would pick something slightly (or completely) different.

I wonder, is it because our tongues are different and the food does indeed taste different, or is it our brains that interpret the same taste differently? Also, what evolutionary purpose does this serve? To me it only makes planning the dinner a pain without really adding anything to our lives.


texts:
An image from this question (and originally from Karl Niklas' computer model) has prompted the following question:

The branches in this tree divide with increasing frequency as we progress from the bottom of the tree. This clearly makes sense from the perspective of light absorption efficiency and is a phenomenon I have often observed in real trees. The model in question created trees for optimal light favourability, stability and reproductive ability (in this case just light favourability). What other factors affect the length at which a branch splits or produces an offshoot? How does this initial sprouting determine the 'final' shape of the tree's branches.

DISCLAIMER: appreciate that perhaps this question is too broad - my initial interest in the specific subject was from a more mathematical standpoint (I am a physicist). I am simply seeking a more biological/complete explanation to the phenomena.


texts: Is our genome decaying (see "Genetic Entropy"), and, if so, is this evidence for our genome being "young"?

texts:
In the book Genetic Entropy & the Mystery of the Genome the author says that the genome cannot be old because the genome is "decaying". Decay is a very subjective term, but in this case he means that the fitness of humans is going down not up. Is it true that our genome is decaying over time, and that the fitness of humans is decreasing? Here is a quote from the book, that might explain his argument:

  Kondrashov, an evolutionist who is an expert on this subject, has advised me that virtually all the human geneticists he knows agree that man is degenerating genetically. The most definitive findings were published in 2010 in the Proceedings of the National Academy of Science by Lynch.4 That paper indicates human fitness is declining at 3–5% per generation.There is really no debate on current human genetic degeneration.

Perhaps this more shines more enlightenment in my question. This idea of human fitness going "down" is my main concern. Essentially, in his book he claims that because we are going "down" (meaning fitness is declining) not "up" (whatever that means) our genome must therefore be young. If I understand the issue correctly, mutations "create new information" by creating different proteins or leading to an abnormal protein products. However, I thought that the force of natural selection should be strong enough to get a rid of those genes that are so and so responsible for our fitness declining.

Sanford, John C., and John R. Baumgardner. Genetic Entropy & the Mystery of the Genome. Waterloo, NY: FMS Publications, 2008. Print.

Feel free to point me to similar questions that may been helpful or are similar to this one.


texts: What kind of spider is in this pic I took?

texts:
What kind of spider is this?

It has a weird black and white backpack looking thing. Found a couple of them in Auburn, Alabama. Any help is greatly appreciated.


texts: Variance in reproductive success and effective population size

texts:
Background

The effective population size $N_e$ is the size of the Wright-Fisher population that experience the same amount of drift than the population under consideration.

The higher the variance in reproductive success among individuals, the lower is the effective population. Consider for example, a case where the variance in reproductive success is so high that only one individual reproduces (selfing for example) and contribute to the next generation. In such a case the variance in reproductive success is so high that the effective population size is reduced to 1.

During a meeting I have encountered the following relationship between the population size $N$, the effective population size $Ne$ and the variance in reproductive success $V$.

$$N_e = \frac{N}{V}$$

It makes intuitive sense to me. In the extreme case where $V≈0$, there is no drift and therefore no loss in diversity, everybody contribute as much to the next generation and therefore $N_e=\infty$. By definition, in a Wright-Fisher population $N=N_e$ and therefore $V=1$ should be correct.

Questions

Where does the equation $N_e = \frac{N}{V}$ comes from? How to derive it? Is it an approximation or an equality?
Is it true that $V=1$ in a Wright-Fisher population?


texts: Have webs woven by LSD-intoxicated spiders ever been studied for their efficiency in fly catching?

texts:
I ask, because I have a different interpretation of the experiments performed on web-weaving spiders. The famous Robert Pirsig maintains that LSD is somehow helpful to web-weaving spiders, because it makes their web more straight. Pirsig seems to imply, as I remember, that the spider is somehow more attentive to its web while on LSD.

However, I maintain that it isn't the case and that it is actually the reverse.  The spider is much less attentive, for it needs chaos in its web to catch the fly!


texts: What is the difference between kingdoms protistae and protoctistae?

texts:
I understand that both kingdoms represent primitive eukaryotic organisms, and both contain both unicellular and multicellular organisms.

What are the points that distinguish one kingdom from the other?


texts: Separating DNA Fragments by Gel Electrophoresis. Are all the strands for one size the same?

texts:
My apologies if my question is too basic, and please point me to a more appropriate forum.  I am reading the textbook "Essential Cell Biology" by Alberts et al, and am consulting other sources as well.  I am reading Chapter 10 about DNA technology and have read how DNA is separated into strands of different lengths by restriction enzymes.  The different size strands can then by separated by Gel Electrophoresis.  I believe I understand these basics. My question is:

Do all strands of the same length have the same sequence of base pairs?  I wouldn't think      so, and this would be a problem in the next step, determining the sequence of one size fragment by  using special base pairs that are lacking a hydroxyl group. Isn't it possible I could have two strands that are 50 base pairs long (for example) that have the same beginning and same end and are thus cut by the restriction enzymes to a length of 50, but are most assuredly not the same within their sequence

The text says that once the different size strands are separated by electrophoresis, you can just cut out one of the bands and work with that.  That makes sense if you are guaranteed to only have 1 strand at that level of the gel agar or if the multiple strands are all the same exact sequence.

If you read this far, thank you.  I think more generally I need to know how many of these segments are produced when you use restriction enzymes and how long the average one is. And is there any guarantee for one chromosone (or all 46 chrmosones) having all the segments be unique sizes (I wouldn't think so)?

And even more generally :), I need additional sources that explain DNA sequencing in simple to understand terms.

Thanks,

Dave


texts: Did insects and arachnids diverge before or after moving to land?

texts:
Question: Are arachnids and insects so distantly related that they were already diverging before their (independent) emergence(s) on land?

I am curious to know what the fossil record and molecular evidence has had to say so far about such questions.

To the extent that arachnids and insects might not be any more closely related to one another than they are to crustaceans, and crustaceans are mostly aquatic, it does not seem impossible/implausible to me that the terrestrial transitions of insects and arachnids could have been independent of one another. In fact, considering that wood lice are crustaceans, one can conclude that there have already been at least two independent terrestrial transitions for arthropods, so postulating a third seems less of a stretch to me.

I suppose the thought process behind this is related to this question. Specifically, to the best of my knowledge, flight emerged several times among distinct insect lineages after appearing on land, in cases of convergent evolution. The fact that no lineage of arachnids ever evolved winged flight while many lineages of insect evolved flight independently of one another suggests that the "fundamental recipe" for insects and arachnids is substantially different, i.e. that they are not as closely related as one might have otherwise thought.