texts: What do you see if you look at your own retina with the same eye? (optical feedback)

texts:
When you record a video while pointing the viewfinder towards the screen showing a live preview you create optical feedback: video example. An anoalogous effect occurs when you turn your microphone towards the speaker.

Once you look at your own retina with the same eye, does our brain create a similar effect as recorded in the video? Or could it be something different all together?

Obviously the best way to find out is to 'just go ahead' and see for myself, but it seems as if I don't have the proper conditions to test this at home: The pupil gets too small in the mirror and thus the retina is plain dark. Such an experiment would require eye drops to force widen the pupil and allow for more light onto the retina.


texts:
What is the meaning of calcium conductance in ion channels. I encountered this in the following text:

  It was established that the µ and δ opioid receptors open potassium
  channels, which results in reduction of calcium conductance (Simon, 2005).

Also why should opening a potassium channel reduce calcium conductance. How are they related ?

Reference:

Simon, E. J. (2005). Opiates: Neurobiology. In J. H. Lowinson, P. Ruiz, R. B. Millman & J. G. Langrod (Eds.), Substance abuse : a comprehensive textbook (4th ed., pp. xxiv, 1421 p.). Philadelphia: Lippincott Williams & Wilkins.


texts: Which algae grow fastest under optimal conditions?

texts:
I'm interested in what the fastest growing microalgae are under optimal conditions for photoautotrophic growth (energy from photosynthesis only).  Fastest can be interpreted as either shortest doubling time, or maximum biomass yield per day per unit area.

Many of the algae investigated for biofuels are fast-growing, for example Nannochloropsis and Ankistrodesmus.  There are many publications that give yields in pond culture or in outdoor photobioreactor, for example Nannochloropsis at 20g/m^2/day (dry mass).  However it is not as common to see yields for lab photobioreactor (axenic, possibly with continuous illumination, and all other conditions optimized for fast growth).  I'm mainly interested in what family of algae would be evolved for fast growth, and where they may be found in nature.

EDIT As one of the answers pointed out, algae can grow heterotrophically as well and that may not be a fair comparison.  I changed the question to be about autotrophic growth (from photosynthesis) only.


texts: How to convert between Kunitz units and Enzymatic units?

texts:
I've googled around and there has been the common answer of 1.5 U = 1 Kunitz Unit, but none of those answers have come from a reputable source, so I am really doubtful. :(

The enzyme I use comes in 723 Kunitz units per mg protein, but I need 600 U per mg of DNA being used in my procedure. I do not know how to properly determine how many Kunitz units equivocate to Enzymatic Units, and vice versa.


texts: How fast do lipids on the inside and outside of a lipid bilayer exchange?

texts:
Biological membranes normally have different composition of lipids on the inside and outside (ref 1, ref 2).  This is maintained both by how new lipids are added to membranes, and by specialized enzymes (flippases).  Certain lipids being on the "wrong side" is an important signal (eg for apoptosis).
My question is: how fast do lipids from the inside and outside exchange spontaneously?  In a patch of membrane with no enzymes, how long until half the "inside" lipids have flipped to the outside and vice versa through simple diffusion?
I did a search but couldn't find any specific paper that measures the spontaneous exchange rate.  I'd be very interested in a definitive answer - could be just order of magnitude, but based on real measurements.
UPDATE This is important for figuring out the inside/outside composition of membranes in real scenarios when they're no longer being maintained in an asymmetric state: for example enveloped viruses, but also microparticles, dead cells, etc.


texts: Eukaryotic equivalent of bacterial tmRNA

texts:
According to this Wikipedia article,
tmRNA is only found in bacteria, with its purpose being to “rescue stalled ribosomes”.

This brings me to the question of is there a eukaryotic equivalent of this RNA? If not, how do eukaryotic cells (or any other type of cell) prevent or stop stalled ribosomes?

Every time I search for “eukaryotic rescuing stalled ribosomes”, I am constantly only  presented with references to tmRNA in E. Coli.


texts:
"One can measure two or more signals simultaneously determined by a single feature, i.e.,
  epitope in immunomic microarray DNA microarrays measure one response value for each gene per sample; that is, mRNA concentration produced by the gene but a single epitope
  can generate different response values corresponding to different epitopes in peptide–MHC chips. In case of B cell epitope, it can be recognized by different isotypes of immunoglobulins, so here, one can measure both intensity and quality of antibody response."

These few lines are from the book:
http://www.springer.com/biomed/immunology/book/978-1-4939-1114-1
Chapter 3

What does measure of one response value for each gene per sample mean?
Different response value means??
how is intensity and quality both are being measured??


texts: Why is it that bacteria and fungi cannot develop resistance against essential oils?

texts:
I wonder why bacteria and fungi cannot develop resistance and mutate agains essential oils?

For example, some fungi get killed by oregano oil.

Being not a biologist, I hope my question is not so stupid..

Thank you!


texts:
I just read Andy Weir's "The Martian" (which was very good) and one line made me wonder:

  [...] a human body only borrows water.

Is that true? Does all water "that goes in, go out"?


texts: What tool can I use to align multiple protein sequences to one reference sequence?

texts:
I have a protein of interest which is ~300 amino acids in length. I also have around 40 short sequences (all 9 amino acids in length); these are all very different from each other. I would like to perform multiple pairwise alignments to see if these sequences match up with (or have high sequence identity similarity) any areas in the protein of interest.

Since the short 9-a.a. sequences are very heterogeneous, they will have similarities in different regions of the protein of interest. I would like to know if it is possible to perform the alignments for all 40 sequences in one step, rather than using COBALT 40 times (and checking each of the short sequences against the reference sequence individually).

Please let me know if the description of my problem is not clear enough, I would appreciate any help in identifying a way to do this.


texts: Help me understand my membrane potential assignment

texts:
Epithelial with the ability to transport NaCl is bathed in an isotonic salt solution with these values (in mM): 136 Na, 6 K, 140 Cl.
The intracellular concentrations are: 45 Na, 100 K, 13 Cl.

The cell's resting potential is -63 mV and the temperature is 37 Celcius.

Which ions will passively diffuse over the membrane?

My attempt: I calculate the nernst potential of each ion and taking the first ion (Na) as an example I get that it's equilibrium is at 29 mV. So as there are more of these cations outside the cell and the membrane potential is negative, the ions will want to "reach" 29 mV by flowing INSIDE the cell (to increase the membrane potential). I think they will do this by diffusing into the cell? I'm not sure if I am attacking the problem correctly or if it's rather lunging at my abilities in transporters. The NaK transporter is active transport so maybe the do not diffuse at all?? However there are Na channels that can open...Which is passive diffusion..

Calculate the cation permeability Pna/Pk

I have no idea how to do this. I still need more constants in the Goldman equation (Pcl for example) before I could isolate even one of these.

Thanks!


texts: Suggestions for self-studying experimental techniques

texts:
I would appreciate any suggestion regarding self-studying experimental techniques used in biology for a theoretical scientist (candidate).

Maybe I should be more specific. I'm a biology major, but took as little experimental courses as possible, and I didn't paid much attention to those I took. (shame on me, right). Then I got a MS in applied math. When I revisit my molecular biology/genetics and biochemistry textbooks, I realized that they are mostly descriptive.

An experiment/technique oriented textbook would be very helpful for me, especially if it will also provide an overview of the methods.

My purpose is not the make up for the lost undergrad years, change my research orientation or master experimental skills. I'm aware that this is not achievable by reading some texts. My sole purpose is to not get lost on theory/experiment interface. When someone asks how something could be proven experimentally, I want to know what options are there in the field.


texts: Have scientists tried to communicate with Sperm whales?

texts:
I see lots of passive studies of sperm whale click "language", usually focused on fingerprinting to identify groups and individuals. There's application of deep learning, and all sorts of advanced analysis. However, I haven't found any examples of scientists actively producing their own clicks and trying to elicit responses from whales. It seems to me that successful interactions would push our understanding of the clicks forwards much faster with a bit of a debug/test cycle.
Have studies like that ever been done? If so, can I please have links/references to the papers? Thanks!!


texts: I am trying to understand the Shine–Dalgarno sequence. I currently know it is related to ribosomal binding sites, it is only found in prokaryote cells and it is in front of the initial codon. Also, how do you recognize a Shine-Dalgarno sequence?


texts: What is the relationship between cell size and metabolism?

texts: What effect does a bigger cell have on its metabolic activity? I understand that bigger cells need more energy, but surely smaller cells may have high metabolic rates too due to their efficiency?


texts: Allamanda blanchetti fertilization mechanism

texts:
Here is an Allamanda blanchetti flower in my garden.
My question is based on the observation that the flower seems to be devoid of any reproductive structures, i.e., Stamen or Carpel, so how does it set seed? In the picture below it can be seen that the plant isn't sterile and successfully produces seed pods.


texts: Why do same type of fruits come in different sizes?

texts:
Why don't fruits come in exact same size even they're the same type of fruit?

This sounds like an obvious question,

but why are some apples bigger than others?

and why are some bananas larger than other bananas? or some trees grow taller than others?

What affects them to grow in different sizes, although they are from the same type of trees?

Is it because the fruits grew in different conditions?

Are there any articles or research about this?


texts: What was the first known flower meant for a flying pollinator insect?

texts: I think flower ancestors were colorless and sugarless. The first flower then chanced upon using insects by attracting them. Has this flower been discovered and from what ancestors did it evolve from?


texts: Non-monotonic knock-out effects in prokaryotes

texts:
Typically, when performing gene-knockout, the experimenters select one gene to remove/replace-with-junk and then see if the prokaryote can still undergo fission. If it continues to reproduce then the gene is labeled as non-essential; if the organism cannot reproduce then the gene is labeled as essential; and some-times (if the organism can reproduce but only for a certain number of generations) the gene is labeled as quasi-essential.

Typically, if gene X is essential, and you knock-out both gene X and some other gene Y then the organism still dies; this is an example of monotonic behavior. However, this doesn't always have to be the case, it could be that gene X is essential only in the presence of gene Y (for instance if the two proteins produced are in a delicate feedback loop). Is there examples when knocking out gene X makes the organism nonviable, but knocking out gene X and Y maintains viability? In the most extreme case, is there an example where both gene X and Y are essential, but if both are knocked-out then the organism is still viable? I am primarily interested in simple prokaryotes (an answer for Mycoplasma genitalium or Escherichia coli would be best) but more complicated organisms are preferred over no answer.


texts: I will be joining a team of field biologists on a trip to some uninhabited islands in the tropics. We will be collecting bird blood samples for some genetic research. We will be out there for two weeks. Will blood samples in lysis buffer last for two weeks with out refrigeration or freezing them? Or should we do our sampling closer to the day we leave so they have less time in tropical heat?


texts: I understand what miRNA are, but I'm unsure of what cognate means. Looking at this post, it seems that a cognate miRNA is a known miRNA vs. a recently discovered/possible miRNA. Is this thinking on the right track?


texts: Significance of synthesis of D-glucose in plants..?

texts: why plants can only synthesize D-glucose why not L-glucose along with D glucose. I know it very well that plants have only enzymes which can synthesize D-glucose but Why not they have enzymes which can also manufacture L-glucose. So that we could have mixture of L and D glucose molecules? What is the significance of synthesis of only D-glucose by the plants ?


texts: Why do humans require vitamin B12 supplementation while herbivores do not?

texts:
This question came about from reading the comments of this (very unclear) question, which the author did not properly clarify.

Vegans are often recommended to take vitamin B12 supplements, as the vitamin is not present in sufficient quantities within vegan food. This implies that plants do not produce (or need) vitamin B12 in their metabolic processes.

However, herbivorous animals do not require any vitamin B12 supplementation, yet contain significant amounts of vitamin B12 in their food products.

What, then, is so different about the digestive tracts of humans and other herbivores that prevent humans from obtaining sufficient vitamin B12 from bacterial sources? Can humans be supplemented with gut bacteria from herbivores, allowing them to obtain sufficient vitamin B12 while on a vegan diet without requiring supplementation?


texts: What is this creepy little thing that I found sticking on my bathroom wall?

texts: I found this creepy looking thing hanging on my bathroom wall. This is actually the 2nd time I have seen it. The first one I saw looked kind of dried up already stuck in between the walls. But this looks fresh and new. It's scary and gives me goosebumps just looking at it. Can somebody pls help


texts: How are Antibody and T-cell receptor different?

texts:
Since the helper T-cell bonds with specific antigen presented by dendritic cell and that same helper T-cell also activates B-cell by bonding with antigen presented by B-cell, it made me think that the antigens presented by both of them should be same.
If that specificity is true, then what's the difference between an antibody and T-cell receptor? Because both T-cell receptor and Antibody are specific to an antigen.


texts: What is the difference between osmotic potential and osmotic pressure?

texts: Which term is used to calculate water potential? Does osmotic potential mean the same as solute potential?


texts: Will a sandwich assay work with a GST 26 antibody/protein?

texts: I have a GST 26 kda antibody, and want to use it in a sandwich lateral flow assay. Are there enough epitope regions for both antibodies to bind to the protein?


texts:
Kindly help me identify this thing found in beach
Chennai, India . Size would be just 1.5 cm in diameter..across maximum size. It's shelled and has something inside it. It make a small noise when it is shaked completely closed on all sides. It's hard surface ( but " fine" texture ) to touch.


texts: Classification of degree of infested areas by pine processionary moth on regions

texts:
I'm making a thesis about pine processionary moth distribution on the regions of algeria!
i'm making tests about if there are spatial autocorrelation of this insects on the regions.
and i'm doing also hierarchical clustering of (degree of infest, small defoliation, medium defoliation, and high defoliation, and lattitude and longitude coordinates ) on each region to see the regions that have the same caracteristics on the variables i muntioned above!

The problem is that i need some information about the effect of geographical location and climat on this specific insect ?

i have made some statistical tests, and i have found that each year have diffirent cluster caracteristics for this regions, so can anyone help me to know why it's diffirent each year ?

the final thing, if anyone could suggest to me some links, to previous some study on another country maybe , so i can take an idea of what do i have to include and do , and to compare also with my results ?


texts: Can VMD change its cartoon representation for secondary structure according to trajectories?

texts:
I am using VMD to visualise the secondary structure of protein.

The trajectories are from my Gromacs simulation. Firstly I use File - New Molecule... to load the protein.gro file. Secondly I use File - Load Data into Molecule... to load my protein.xtc trajectories.

Then I use Cartoon to visulise the structure. As I drag the time frames, all the secondary structures (e.g. alpha-helix, beta-sheet) keep the same. But I am pretty sure some of them are changing, as I look into the Timeline analysis for secondary structure.

So how to use VMD to see the secondary structures at different time frames?

Thanks a lot for @Stefan's help! It finally works! So follow Stefan's guide, and replace the molid with the number under the ID in the VMD Main.


texts: Why do protein solutions have to be alkalised in biuret test?

texts: I’ve read that CuSO4 solution reacts with peptide bonds that connect amino acids to create a violet colour, but the instructions always tell me to add NaOH solution to the protein solution before I add CuSO4. How is alkalising the protein solution before adding CuSO4 solution an aid to this process?


texts: How does horse extract the energy to needs from a relatively small digestive system?

texts: Recently I saw Inside nature's gaints episode on horse, and was fascinated about its internal organisation. And my question is that they have a very large lungs to accommodate, but a relatively smaller stomach. But other herbivores like the hippopotamus have a very large digestive system even though they need less energy than horse. How does horse manage this problem? How do they get that much of energy even though it had small digestive system and more over it is an herbivore?


texts: Which spider species is this, and is it dangerous?

texts:
Sorry for a quite bad picture. I was afraid to get closer!

Seen in Croatia, inlands, not near sea. As he is on the picture there with the legs stretched out, I'd say he was about 8-10 cm in length.


texts: Can animals make their own unsaturated fatty acids?

texts:
I know that animals can't make poly-unsaturated fatty acids (PUFA) and so require them from dietary sources. For eg.Omega -3 and Omega 6 fatty acids.

My questions : Can animals synthesize other unsaturated fatty acids from scratch? If not, does the unsaturated fatty acids in the phospholipids of plasma membrane of animals come only from dietary sources?


texts: What is meant by 'proteolytic activation' of a virus?

texts:
Noob biologist here. I suspect that at the first stage this means 'activating the virus by lysis of a surface/spike protein'? Seems kind of obvious, but I put it here in case 'proteolytic activation' is not in fact merely a subset of 'virus activation', and means something slightly different.
Second, if the above interpretation is correct, what precisely do we mean by virus activation? Is it the release of viral RNA into the host cell cytosol? This would be my guess, as it is necessary (sufficient?) for replication of viral RNA to commence, and viral replication to occur. Another idea is that 'virus entering host cell' is enough to constitute viral activation, though I suspect some viruses can enter cells and remain dormant there. Hardly seems like activation to me.
Would really appreciate clarification of this terminology so I don't have misconceptions when reading literature.


texts: Is it possible to both extract DNA sequences from plasmids and fuse them using primers for Gibson assembly?

texts:
Maybe I'm overcomplicating this, but I'm having some issues with a construct.

So, I have three plasmids containing a total of eight DNA sequences that I need to fuse into one linear sequence. I plan to fuse the sequences using Gibson assembly. However, before I can fuse them, I need to amplify (PCR) them out of their plasmids.

I would like to use as few primers as possible, so my question is this; can I use the Gibson assembly primers to amplify them out of the plasmids and add the overlap sequences separately, then fuse them all together in a separate reaction without primers? Would the overlap sequences already added to each sequence separately be enough to act as primers for assembly? Even better (but I doubt it would work), could I amplify them out of their plasmids and fuse them in the same reaction?

If both these scenarios are unrealistic, I can still just order another round of primers to extract the sequences from their plasmids, but I would like to just use the primers I have if I can.


texts: What is the connection between exercise and muscle growth

texts:
From a physiological perspective, all that is done during exercise is the expending of energy in the form of ATP to fuel muscle contraction and extension.

When I looked up why muscle grow due to exercise, there is the claim that recovery of micro lesions formed during exercise enables slight growth of muscle. I am not sure how micro lesions are formed and intuitively, these micro lesions should cause atrophy of the muscle rather than strengthening of the muscle fibers.

Further there is no logical connection as to why muscle fibers would be strengthened rather than just restored to its previous form during rest.

Can someone help me make the mental leap from the consumption of ATP through exercise to muscle growth?


texts:
Not all carcinogens are mutagens. Alcohol and estrogen, for example, does not damage DNA.

It's one of the assumptions of the Ames test that mutagenicity implies carcinogenicity, but is this always the case? I assumed that it was, but then I saw one of the comments here. I did some more research but the internet seems to be reluctant to be definitive on the subject. This guy claims 'no', but I'd prefer sources or at least a response that handles counterexamples like HPV. This paper claims 'yes', but doesn't list any specific examples. Some mutagens might be more specific to genes involved in cell cycle regulation, so I could see how a weak mutagen is a powerful carcinogen.

My question is, can you go the other way? Are there mutagens that just do not cause cancer? If they do not exist or are not known to exist, are they even possible?


texts: Why is a solution of cesium chloride used in Meselson & Stahl's DNA replication experiment?

texts:
Centrifugation involves separating particles of different sizes, masses, density and etc.
In the experiment, the DNA macromolecules are suspended in a solution of cesium chloride gradient and then centrifuged.
Why is cesium chloride needed? Considering the possible DNA produced in the experiment will be the same size but of different mass resulting in different density, DNA will be separated based on their density by virtue (without the need for cesium chloride) under the influence of a centrifugal force.
I noticed someone asked the same question on Khanacademy but there was no answer for it. Other websites I found doesn't seem to offer a valid answer e.g. here which says " the DNA comes to equilibrium in the gradient where its density equals the density of the surrounding CsCl" which I think doesn't really matter when considering the argument I proposed above in the third paragraph.
Here is a diagram of the experiment for reference. Thanks in advance.


texts: On the way from school to home, I came across this strange looking fruit that looks similar to a potato and it grows on a tree. Can you identify it?


texts:
This red spider has set up a web in my yard, in South Eastern, Texas, United States:

The spider itself is about an inch long (2.5 cm), and is predominantly red to brown in color, with red legs, and a very striking white line straight down the center of her back. The web is quite large—at least 4 feet (1.2 m) in diameter. It seems to be nocturnal, as I haven't seen it during the day, yet I've walked into the web (or nearly walked into its web) twice at night. Unfortunately, due to lighting conditions I wasn't able to capture the color particularly well.

I've searched but haven't found a species that looks like this yet.


texts:
Oxygen consumption rate (OCR) is defined as the rate at which cells consume oxygen. I reason that for cells not capable of photosynthesis, OCR is strictly non-negative.

That was until I read this article which provides a graph with negative OCR values. Could someone enlighten me as to how this might be possible? If the cells are consuming no oxygen, I would expect OCR to be zero, not negative.

Scientific Paper:

http://www.pnas.org/content/108/33/13829.full


texts:
India, It was growing outside.

April 2017

Center part of the flower giving me Heebie-jeebies.


texts: Does Sansevieria trifasciata really absorb Carbon Dioxide at night?

texts:
There's a claim that Sansevieria trifasciata (Mother-in-law’s Tongue) generates oxygen from carbon dioxide during the night.

This seems surprising to me: that process requires energy; plants generate O₂ from CO₂ through photosynthesis, requiring light. So not photosynthesis, and no CO₂ absorption, at night.

Am I missing something, or is this claim false?


texts: Can far-UVC light be safely used as germicide? (help understanding a paper)

texts: I've been trying to familiarize myself with the literature on far UVC light as a germicide.  My question mostly pertains to figure 4 of this paper. The paper investigates the efficacy of 207 nm light for killing MRSA without damaging human cells.  Figure 4 shows that you can get 4 logs of cell kill for MRSA with relatively little damage to human cells.  The authors treat this as a very promising result.  This is where I'm confused:  Yes 207 nm light kills MRSA selectively, but it still kills a lot of human cells: to get 4 logs of MRSA cell kill, you need a fluence that kills 80% of human cells.  Killing 99.99% of bacterial cells while also killing 80% of human cells seems obviously not good enough.  But the authors don't touch on this point: They just point out that it kills 5000x more MRSA cells than human, and interpret the result as promising.  What am I missing here?


texts: What's the difference between an embryo and a fetus?

texts: The most I've been able to come up with is that fetuses are embryos slightly farther along in their development. Is that correct?


texts:
I am a Engineering University student, in my last year of completion of my degree. I had interests in biochemistry and biology since I was a kid, and been learning about that side by side in my spare time.

I want to get into biomedical research and buy a suitable microscope for that purpose.

After following various guides and info I could find, I have decided to go for a well manufactured compound microscope of high quality. But these fishy companies majorly Chinese are troubling me, with top companies like Leica, Nikon, Zeiss etc having quite same reviews.

I haven't yet decided the Manufacturer I want to buy from. I am willing to go for around $1000 for a well reputed manufacturer. There are numerous choices even within the top companies.

What are some best suggestions and recommendations for Compound Microscope according to my needs?

all suggestions are welcomed.

edit 1: Many Indian manufacturers called me, but I want some reliable global manufacturer, well known by its quality. I also need some expandable scope for future upgradations. Am I going the right way or should I buy from Indian manufacturers? and which manufacturer if well known one?

edit 2: The price I am going into is $1000.


texts: Fe(II) and Fe(III) transport from rhizosphere across plasma membrane

texts:
Does the graminaceous plants have passive uptake of Fe(II) via a passive Fe(II)-transporter enzyme? Or it it only dicots and non-graminaceous plants that have the Fe(II)-transporter enzyme? Also, can Fe(III)-reductase reduce Fe-EDDHA (Ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)) and Fe-DPTA (diethylene triamine pentaacetic acid) without the cost of energy?

Best regards,

Mathias


texts: Protein phosphorylation in the cytoplasm. Typical time scale?

texts:
Is there a typical protein phosphorylation rate in the cell cytoplasm under physiological conditions, or at least an upper-bound?

Suppose a protein $A$ is being phosphorylated into $A^*$ with the first order reaction

$A \to ^k A^*$

where $k$ is the reaction rate ($k$ unit is $\rm time^{-1}$).

In reality a phosphorylation reaction involves multiple agents (protein, enzyme, ATP) and multiple reactions, therefore cannot be accurately mapped onto a first order reaction. However this makes sense if we are only interested in the order of magnitude of $k$. According to this first order reaction the evolution of the $A$ concentration is given by
$$
\frac{d A}{dt}=-k A
$$
and therefore $1/k$ is the time scale at which $A$ vary.

So my question can also be formulated as: suppose that at a given time a cytoplasmic protein $A$ starts to be phosphorylated into $A^*$. What is the typical time scale at which the concentrations of $A$ and $A^*$ reach their equilibrium values?

From few things I read it looks like it is of the order of seconds or minutes or hours, and 1 second seems to be an upper bound. Any references?


texts: I saw this bug many times in my room this spring. Can any one help identifying it?!


texts: What are the reasons that soap has so different smell and flavour?

texts: Everybody has tried to taste soap in their childhood. One would think that if soap has a tasty smell it would have tasty flavor too. But we know it is not true (in the common cases). But why is there is difference in the senses to our noses and tongues for the same soap?


texts: Can paper/plastic currency serve as a medium for pathogens?

texts:
http://www.nytimes.com/2009/12/15/health/15real.html seems to indicate for a surface, to serve as a medium, the following properties are relevant

animation
humidity
temperature

The article however does not elaborate on the properties a surface must possess to serve as a medium - albeit i would figure it may vary from one virus/bacterium to another.

The same article also states

... when objects in a hotel room — light switches, telephones — were contaminated
with a  cold virus, 60 percent of healthy volunteers picked up the virus when they
touched one of the objects an hour later. Eighteen hours later, the transmission rate
was cut in half.

When currency changes hands we rarely ever know whether it may , within a reasonable timespan, have passed through an agent/carrier.

Sir Dumpty loves to sneak off with a currency note to get me to chase him. He is protected; another member of his species may not be so protected. For that matter a person infected with, say, the common cold virus may have passed a note/coin/card to the vendor at the store within a minute of sneezing/coughing into his/her hand. What if the same person , instead, suffered from TB?

So ... can currency serve as a medium for transmission of pathogens?


texts: Generating all possible conformations of an Intrinsically disordered protein

texts:
I want to simulate interaction between the bHLH-LZ domain of c-Myc encoded protein and a test ligand. Since the domain is intrinsically disordered, I want to generate all possible conformations of the IDP to run several iterations of simulation, each time with a different conformation. How can I do so? I would really appreciate if you could explain me what is the basis of these conformations and explain the concept?
Thank you!


texts: Characterising mechanisms responsible for generating structural variants

texts:
I have a high-quality set of structural variant breakpoints from tumour/normal WGS data, and I am interested in digging into the various mechanisms that might be involved in each event.

There are several mechanisms that are proposed to play a role in generating structural variants, including Non-allelic homologous recombination (NAHR), non-homologous end joining (NHEJ/MMEJ), alternative end joining (Alt-EJ) and several replicative mechanisms such as Fork Stalling and Template Switching (FoSTeS/MMBIR).

Each of these are distinct processes, that have occur at different time points in the cell cycle and have different potential for generating genomic rearrangements. However, I have not been able to find a consistent requirement for each mechanism.
I would like to know if anyone can think of a authoritative source for criteria I could use to form a working hypothesis as to the mechanism underlying each variant.

For example, if I have a 10 Kb deletion with 4 bases of microhomolgy at breakpoints I'm currently classifying it as an Alt-EJ event (largely based on the criteria I list below).

Several specific questions:
Microhomology at breakpoints is an essential requirement for several of these mechanisms (FoSTes/MMBIR). However, there appears to be no consensus as to whether this must occur exactly at the breakpoint, or whether it can be several bases away (for example here).

Secondly, according to this paper, the criterial used to classify structural variants is as follows (taken from the MeerKat manual):
NAHR: non-allellic homologous recombination, >100bp homology.
alt-EJ: alternative end joining, 3-100bp homology.
NHEJ: non-homologous end joining, 0-2bp homology or 1-10bp insertion at deletion break point.
FoSTeS: fork stalling and template switching, template switch, >10bp insertion at deletion break points.

However, almost every paper I read suggests different criteria, for example FoSTes events are normal associated with microhomologies at breakpoints rather than insertions.

Can anyone suggest a "consensus" of requirements for each mechanism?


texts: Why the C6 intermediate molecule in the Calvin cycle is so unstable

texts:
During the Calvin cycle, it is speculated that after Ribulose bisphosphate carboxylase/oxidase carboxylate ribulose bisphosphate, a 6C molecule is created and decomposed instantaneously into two phosphoglycerates because it is extremely unstable so:

Can anyone clarify why this molecule is so unstable? and...

how we know this molecule exists?.

I did not find anything useful while researching this, perhaps I'm not looking properly or there is no debate about it.


texts: What does it mean for a gametocyte to "reprogram" the genes inside of it?

texts:
I am aware that frequently clones have genetic defects not present in the donor organism, even though the two are genetically identical. The reason for this is that apparently the enclosing gametocyte "reprograms" the genes inside of itself and during the cloning process, this reprogramming is not completed because the novel DNA is in the host gametocyte for too brief a period. Here is a quote from an article on the subject:

  In cloning, scientists slip a cell from an adult into an egg with its
  genetic material removed. The egg then reprograms the adult cell's
  genes so that they are ready to direct the development of an embryo,
  then a fetus, then a newborn that is genetically identical to the
  adult whose cell was used to start the process.

What do they mean by "reprogram" the cell's genes? How can a germ cell modify its own nucleus in a way that would not affect the base pair sequencing?


texts: Can parents' learned traits be transmitted genetically?

texts:
I am wondering whether a behavioral trait (e.g. fear or stress experienced in the lifetime of the parent) can be transmitted genetically to its offspring?

I understand that a behavioral tendency for stress acquired through evolutionary time can be transmitted from parent to child, but I'm wondering whether a trait not present before can be transmitted between 2 generations.

For example many studies claim that offsprings of holocaust survivors inherit psychopathological disorders. I'm wondering how this inheritance could occur genetically given such a short time period?


texts: "Next generation" brain scanners, can they detect CTE?

texts:
I've just read the news that a "new generation" brain scanner is under development. I wonder whether they can detect chronic traumatic encephalopathy. I haven't been able to find the paper about these new brain scanners.

So is it possible to detect CTE (during life of the patient, i.e. non post mortem) with this new device, and if not, is there any chance it will be possible in the future?


texts: What are the consequences of drinking water with food?

texts:
Does drinking water with a meal release lesser energy/glucose into the blood stream due to a diluted digestive mixture ?

For simplification : If a person eats 100 grams of cooked jasmine rice with no water in take, when digested in 90 minutes  releases, say, a 100 calories. Then, if  the person eats 100 grams of cooked jasmine rice and drinks 50 ml of water along with it (during/after) (basically, halving the power of the digestive juices) then will the energy released be 50 calories ?


texts: If oxygen deficiency is bad even for a short while, why do people swim?

texts:
This may be trivia to many of you.

Textbook says the oxygen deficiency, even for a short while can injure our cells. Then why do people go for sports like swimming? (where rhythmic breathing is required yet, there's a practical possibility of holding the breath longer than usual inhale exhale process) I am looking for a reasoning from cellular biology/patho-physiology/respiration aspect. And not because swimming or any other such exercise is anyone's choice/preference.

So my question is: during sport like swimming, does the oxygen level in our blood drop below a critical level, that cells might suffer from lack of oxygen?

Also found some relevant information here.

Currently referring to this online text : Swimming Fastest: Physiological Responses to Exercise.


texts: Are all antibodies against a common antigen identical?

texts:
I understand that when some antigen (e.g., virus, bacteria, etc.) is recognized in the body, antibodies specific to this antigen are produced that, in turn, bind to the antigen and effectively neutralize them as a potential threat to the organism.
Are all the antibodies that are produced against a specific antigen necessarily identical?  Either within a single organism (e.g., a single person), or between different organisms (e.g., between different people, different species, etc.)?  If two people get sick with the same disease, develop antibodies, and recover, are these antibodies the same?  If a human and some other animal get sick with the same disease, will the antibodies each develop match?
Key to the operation of the antibodies is their specific recognition/binding of the antigen.  I assume that the structure and composition of the antibody is tuned to bind to specific exposed moieties on the antigen.  I can imagine that there are many different potential binding sites on the antigen to target and many possible combinations of ways to recognize those sites by the antibodies.  I would think that it would be a remarkable coincidence (highly unlikely) if separate organisms both, independently, happened to develop the same “molecular strategy” for recognizing a particular antigen.  This outcome seems to be implied in this question,
How are antibodies specific for a disease detected in the blood if everybody produces a different antibody for the same antigen?


texts: SARS-CoV-2 : does vaccination provide a better immunity than being sick and recover?

texts:
I recently read in the news that countries are thinking to offer a "green passport" based on the vaccination against SARS-CoV-2, allowing vaccinated people to do things with less restrictions than the non-vaccinated :
New York Times
BBC News
Bloomberg
IATA
If those passports are to be put in place, why do they not include people that were exposed naturally to SARS-CoV-2, this number being bigger days after days (60 millions people, 17/02/2021) ?
Does that mean that vaccines offer more immunity than being exposed naturally to SARS-CoV-2 and recover ?
My questions don't address the ethical aspect of implementing a "green passport", I'm only trying to figure out if vaccination offers more immunity than being exposed to the virus. A possible answer to this question can simply be "we don't know so far" because of the lack of feedback on a long term view.


texts: importance of cDNA sequencing of a specific gene in different plants

texts: i want to know what if i made a sequence of cDNA of a specific gene in different plants - what is the important from the sequence and can if found difference between plants , and can i use this sequence to determine cis regulating element


texts:
Micronuclei are cellular structures that are formed as a by-product of, usually, defective mitosis. The piece of chromosome in a micronucleus may, or may not contain a centromere and the DNA is wrapped in a double lipid membrane.

I have tried to find information, but I failed to find out what the fate of these structures is within the cell once formed? And is the DNA within it lost for the cell?


texts: The smell of the shield bug (aka stink bug)

texts: Every time a shield bug flies into my room I try to kill it. Unfortunately, they leave a strong smell after crushing them. Whenever I smell their odor, I always wonder what  the chemical compound is that the bug releases. Does anyone know what the smelly chemical is? If so, please help me out. I always wanted to know what that molecule was.


texts: I have to plan a bioinformatic study on a plant. Microarray data is available for various stress treatments (drought, cold, osmotic and flood stress) on root and shoot tissues. I am a bit confused as to which tissue is more important for the perception of stress and its direct effect. I want to start with one of them as of now, since the study will get too complicated with so many stress conditions and tissues. I am not from a botany field and look for some thoughts. Sorry if my question sounds silly.Thanks a lot.


texts: Evolution and different number of chromosoms? (a non-biologist)

texts:
I understand that a species becomes a different one slowly and in a continuous way. However, the different number of chromosomes is bugging me. Chimpanzees, for example, have 48 chromosomes whereas humans have 46.

I have few guesses which haven't satisfied me at all:

The species are not that different, despite of their different
number of chromosomes, and capable of breeding. The offspring is
somehow healthy and is also capable of breeding. But doesn't that
make the offspring sterile?
The other possibility is, at some point multiple offspring in a
    population formed with, say, 46 chromosomes and the breeding took
    place among them. Even though it doesn't sound impossible to me, what are odds really?

Can someone provide an insight to a non-biologist?


texts: mixing beer with spirits, increase alcohol content?

texts: I decided to mix beer with vodka hoping it would make me more drunk due to the alcohol content but then remembered the rest ISNT alcoholic and i cant figure out if mixing beer with vodka or other spirits would increase the alcohol content or not i would really like an answer to this as well as any health risks if there are any, thanks.


texts: Why aren't introns found on the ends of pre-RNA?

texts: We recently learned in genetics class that exons always cap the ends of nascent RNA. I have been trying to figure out the reason why introns can't instead be found on the ends instead of exons. The end introns would still have their 5' and 3' splice sites, and assuming the splicing machinery functions correctly, these introns would be removed. The only thing I could imagine occurring is inappropriate nucleophilic attack of the end 3' hydroxy group at the end 5' phosphate leading to a single circular RNA. However, in a normal situation where exons are at the ends, if introns in an RNA are  all removed simultaneously than it is possible that the free 3' hydroxy group of say intron 2 could attack the 5' end of another intron leading to inappropriate cleavage of the intervening exon so having exons at the ends does not solve that problem. I don't think my explanation is correct, any ideas?


texts: Is it possible to calculate the energy required to speak a word?

texts:
I was discussing with a colleague whether speaking would require more energy than communicating via instant message (GTalk, etc..).

If this is possible, then I'm particularly interested in whether certain sounds may consume more energy that others, and consequently could one language be more efficient than another.


texts:
I wanted to know whether the boiling of Protein A- antibody complex for SDS-PAGE analysis will disrupt the interaction? and result in dissociation of protein A and antibody?

Thank you


texts:
I'm not asking why the synaptic cleft exists, i.e. what function it holds, rather how.
So I know that the neurotransmitter diffuses across it, it is 20-40 nm wide and contains basal lamina (in NMJs at least), but I cannot find any allusion as to what causes the gap; how the two membranes don't just touch, and how so consistent a distance is created across neurons.
Google has so far failed me on this one, though perhaps I am not searching well enough, any help would be greatly appreciated.


texts: I'm trying to understand if glyphosate is carcinogenic. The information in internet is very confusing. There are many ecological oriented websites which claim it's carcinogenic which I suppose they could be biased, but also news websites stating that World Health Organization says "it's probably carcinogenic". In the other hand the European Union seems to sustain it's not, and it extended its license of use in a "heated debate". is it known if glyphosate is carcinogenic or not, or just there isn't enough evidence to sustain one thing or the other?


texts: Is there variability in genetic combination from the same sperm and egg combination

texts: Given a single sperm and a single egg, is there more than one resulting DNA combination they can form given the same human process of combining that genetic material. That is if I have the  DNA off an egg sequenced and the DNA off a sperm sequenced, can I programmatically determine the DNA of the child formed by that egg and sperm?


texts: Does documentation exist that shows the evolutionary connection between common horses and the okapi?

texts: I'm trying to put together some documentation on the relation between the common (modern) horse and the okapi. I've found a tree that shows that connection but it has no references. I'm hoping that someone has documented this connection somehow.


texts: What is the philosophical definition of life?

texts: How does philosophy define life? And how does it overlap and contrast with the concepts and nuances of other sciences such as biology, chemistry, physics and mathematics?


texts: Cerebral activity during exposure to non - visible light

texts:
Our eyes only have the ability to sense light within a certain spectrum. My understanding is that particular frequencies energize specific cells in our eyes, each responsible for a different "color". When these cells are energized, they each release an appropriate amount of their chemical transmitter to stimulate additional cells and create the perception of the object from which the photos originate.

At what point does this process not occur for non-visible light?

In other words, do we fail to see non visible light because our eyes lack the receptors for other frequencies, or does our brain receive signals that it just dumps because it has not developed to process the information?

Have there been any experiments done involving a brain scan while exposed to non visible light?


texts: Could plants do photosynthesis at moonlight?

texts: Related to this and this but not exactly same; could plants do photosynthesis at moonlight or more dim-intensity light?


texts: What is Balbiani's vitelline body function?

texts:
I tried searching on Google Scholar but I found little to no information about this Balbiani's vitelline body.

I don't even know why it is called vitelline...I've been taught that it can be seen under the electron microscope, is perinuclear, made of mitochondria and lamelle anulatae (I don't know what these are) and you can see it only in primordial follicles.

I initially thought it was involved in protein synthesis, but primordial follicles should be biologically quiescent until they 'wake up' and begin folliculogenesis.


texts: Does the molecular composition of human body change after a period of time?

texts:
I was discussing change in human biology over time and my two in-laws charged in saying, "we're molecularly different after x". I didn't pay attention to what time period they exactly mentioned (hence x).

I am familiar with how mainstream media warps research data to be entertaining. So would serious researchers and scientists consider bold statements such as "we (humans) are completely different after 6 years!" as nothing more than anecdotal?

I'm not talking about decomposition after death but rather about processes in the live body.


texts:
A major difference between simple diffusion and facilitated diffusion is that facilitated diffusion has a maximum transport and velocity; the rate of diffusion is limited, whereas in simple diffusion, it isn't.
Ligand Gated channels (like any protein 'channel') transports molecules through simple diffusion, so they should not be saturable, but how does that make sense ? The channels open by the binding of a specific ligand/molecule, can't they be saturated by this ligand just like carrier proteins are saturated by the substance/molecule which will pass through ?

If they were in fact saturable, how are they considered to be part of simple diffusion?


texts: AlphaFold: How do they determine the 100% accuracy threshold?

texts:
From what I read, it seems the current situation is like this: latest cutting-edge lab techniques get to an accuracy of around 90%. For example, they put a protein under an electron microscope or something, and from the images obtained they achieve a precision of 90%. Now Deepmind features an AI that has demonstrated in contests that it can also virtually fold proteins to 90% accuracy. Therefore, the problem is kind of solved.
Please correct me if my interpretation is wrong. But if it's correct, then a big question remains: how the hell can they know if a configuration is 100% true? Even the best technology can only reach 90%, so where do they get that 100% for comparison?


texts: What differences in effect does fast repetitive exercise have compared to slower muscle-building exercise?

texts:
As a drummer who likes to play high-energy music (fast, aggressive metal) it's safe to say I burn a fair amount of calories when doing so. But I've been drumming for over a decade and despite the amount of it that I've done, it hasn't really had any (visible) effect on muscle growth. Every time I drum I try and push the limit of how fast I can go until I start to ache, so I'm definitely doing something to the muscles in my arms and legs, but it definitely isn't building mass.

I remember reading somewhere that speed based exercise can actually reduce muscle mass as the body tries to make itself more efficient, but heard no evidence to support this or an explanation of how.

Can someone please explain to me how exercise such as fast drumming affects muscle growth and development in relation to traditional muscle building exercise like lifting weights?

I am looking for a explanation of the biology behind this by the way, not fitness advice.

Clarification - for non-drummers, the "speed exercise" I'm referring to is what are called blast beats, where the aim is to keep an often inhumanely fast repetitive beat going. It's common in more "extreme" music such as death metal. While trying to maximise efficiency by minimising the amount of effort required is the goal, the muscles required are undergoing a rapid contraction-release cycle, often sustained for minutes at a time, and sometimes for an entire song.


texts: How exactly is glyceraldehyde 3-Phosphate reverted to ribulose 1,5-bisphosphate for the continuation of the calvin cycle?

texts:
Around 6 molecules of G3P is produced at the end of the Calvin Cycle (light independent reactions of photosynthesis), and 5 of which are reverted back to RuBp.

The general equation that I read is 5 G3P -----> 3 RuBp using 3 ATP.

It however doesn't seem to add up (regarding balancing of the atoms) as 5 phosphates would be converted to 6.

I would appreciate a link to any resource explaining this process in detail.

Thank you and have a nice day ^^


texts: What limited the brown bear's North American range?

texts:
Black bears range across North America, except for open areas like grasslands and tundra. It's generally assumed that they're simply vulnerable to attacks by larger brown bears and need trees as a refuge. (Brown bears generally can't climb trees.)

But the brown bear's range didn't extend much farther east than the Missouri River. If there was sufficient food for black bears in the Eastern forest, one would think brown bears could have survived there.

Has anyone suggested any credible theories to explain the brown bear's North American range? (The best guess I can come up with is that black bears may have been better foragers and/or occasionally killed brown bear cubs, simply eluding brown bears by climbing trees.)


texts: If cytoplasmic determinants are distributed before fertilisation then how can an amphibian's embryo, whose dorsal side is determined after fertilisation develop ?


texts: this insect I found on a stream in the southern region of Bangladesh. Its dorsal part is fully black and head and thorax is yellowish with black spot. Body size approx. 5-6mm, limbs 8-10mm


texts:
Spent a half hour googling this and the best I could find was this:

  Now for some rhymes: Arginine = R. R we having fun yet?
  Asparagine = N The kNights of Ne say "Ne".
  Glutamine is a cute amine = Q
  I say "glutamate"/a former vice president says "glutEmate" = E
  ditto with AsparDic acid = D
  Fenylalanine makes tasty italien sausage = F
  Theres are two rings in tryptophan, and there are two v's in W = W
  Tyrosine = Y, Y? Because we love biochemistry. Source: One letter codes, rhyme and reason


texts: Which literature/study/myth spurred the idea that urine is sterile?

texts:
There is a seemingly unfounded mantra that a person's urine is sterile who is not suffering from a UTI.

So far I have found convincing evidence to the contrary; urine is not sterile. This poster abstract and publication by Hilt et al., 2014 shows that urine may not be sterile. They list 6 other articles (references 3-8) that also found evidence for microflora in healthy urine, the urethra, and the bladder. In some of those studies males were used, and some used females. This makes a convincing case for non-sterile urine.

But why does this mantra persist; where does it come from? Is there a paper that demonstrates the sterility of urine that I have missed? Even if it is old literature, or pop culture, I'd appreciate it.


texts: A coeloblastula is that type of blastula which has a fluid-filled cavity. Since the blastocyst of mammals has a fluid-filled cavity too, can it be called a coeloblastula? My book however mentions the two as different, and it gives the frog as an example of animals having the coeloblastula and mammals as an example of having the blastocyst.


texts:
As anyone who's ever sneezed can tell you, it's caused by irritation in the nose.  And the answer to a question on this very SE attests that "sneezing is a reflex, partially autonomous, to clear the nasal cavity of particles that don't belong there."

That being true, the sneeze mechanism is a little bit strange: if you hold your hand up in front of your face when you sneeze, you'll feel that all of the rapidly-expelled air that ought to be cleaning out your nasal cavity is coming out your mouth, not your nose.  In fact I don't think I've ever felt air coming out my nose when I sneeze.

So what's going on there?


texts: Do axon grows after cutting/damaging of some of its part?

texts:
Do axon grows after cutting of some of its part to near original place?

Do axon restores after local damaging of some of its part?

I take https://class.coursera.org/neurobio-001/ classes and learn that axons are very long. So it is interesting if they able to restore connection to far places parts of body...

UPDATE

https://en.wikipedia.org/wiki/Axon_guidance


texts: Can mexican salamander regenerate any organ?

texts:
Mexican salamander or few other species of salamander can regenerate limbs, tail etc. Do they have HOX genes for vital organs like liver, heart, brain, kidney?

If brain is damaged, can salamander grow it's brain to normal functioning again ?


texts: An efficient and free method of assembling a large number of Sanger sequencing reads?

texts:
I have a rather large number of Sanger Sequencing reads.

Is there a automated method in either Ugene or a similiar freeware that allows you to quickly assemble forward and reverse reads. Ideally something where the suffix of the filename will allow the software to automatically know which is the forward and reverse read.

Any help would be much appreciated as I'm not keen to do each sequence by hand in Bioedit.


texts: Is numbness the absence of one or all touch sensations?

texts:
I am studying the effects of tetrodotoxin and its symptoms when consumed. Numbness is one of the first sensations reported.

But I googled numbness and I couldn't find information about whether this means all touch sensations (e.g. thermal, mechano, etc) have to be absent for numbness or just one specific kind.

My Question:

Can someone

Define numbness
Explain whether numbness is the absence of one or more than one or all touch sensations.


texts: Why do neurones use chemical signalling at synaptic junctions?

texts:
When a neurone fires, it sends an electrical signal that jumps down the axon via the nodes of Ranvier very rapidly. At a synaptic junction, chemical Brownian diffusion signalling with receptor surface proteins is relatively slow and is often exploited by venoms and susceptible to toxins (on the plus side it's the reason a lot of medical drugs work). It seems flawed for evolution to have selected for this rather than some alternative quicker and more direct electrical interface.

Question. Why are chemical synaptic interfaces used in higher organisms at the synaptic junction?


texts: How can P450 distinguish between foreign and native compounds?

texts: It is my understanding that P450 enzymes are capable of selectively degrading compounds that enter the cell from the outside (e.g. synthetic drugs) without damaging compounds that are metabolic intermediates normally found in cells. What is the mechanism that provides these enzymes with the ability to distinguish the foreign compounds that are substrates from the normal metabolic intermediates that are not substrates, if they are structually similiar?


texts: What is the criterion for genetic similarity among siblings and humans in general?

texts:
I just started reading Blueprint by Robert Plomin. He makes some well-known statements about genetic similarity which we all have read somewhere but I would like to know what the criteria for genetic similarity actually are:
He writes that all humans are the same for 99% of the 3 billions base pairs of our DNA. I take that to mean something like this: If our DNA had only 100 base pairs and we compare two individuals, those two individuals' DNA would differ in only one place out of the 100 base pairs.
But he also writes that siblings are (on average) 50% similar genetically. I know the rudimentary story of two chromosome pairs, one from mother, one from father, etc. My question is simply how this can be spelled out precisely. I mean, if any two humans are 99% similar in terms of their DNA, how can two siblings be only 50% similar genetically?
I have a slight suspicion: 99% similarity between the DNAs of any two human beings leaves out 30 million base pairs where they are different. Two siblings then are, in addition to the 99& similarity in base pairs, also 50% similar regarding the remaining 30 million base pairs. Thus, two siblings differ from each other in only 15 million base pairs. SO the 99% shared DNA is what makes us human, as opposed to apes, and the rest constitutes the arena in which individual differences take place?


texts: building intelligent structure with random evolution requires series of non useful steps

texts:
In order to build an intelligent design such as a bridge or a mechanical watch, you need a series of non useful steps.

As far as I understand, in random evolution theory, the "intelligence" involved is the process of natural selection.

The problem with this is that natural selection requires that each step be advantageous right away. If I want to build a bridge, I need many steps which would be disadvantageous until the final product which would be advantageous. This would be like trying to write a computer program where each line of code must be advantageous to the program. An intelligent design just cannot be done like this.

How does modern biology deal with this problem? To say it all happened at once, is not possible since the probabilities against this are simply outside the capabilities of a random system. Furthermore even if by some freak monumental event it happened, it would need to happen again many times since there is a huge diversity of intelligent designs in life forms such as lungs in birds vs gills in fish, or sexless reproduction in bacteria versus male/female reproduction in animals (which are fundamentally different).

(Also, as side question has there been ANY experiment demonstrating that such a thing is even possible? I mean for example, to have a computer simulation of random self-replicating molecules, then having an intelligent human being picking out the best version and eliminating the others, then repeating, etc. until you have an intelligent design.)


texts: X-recessive disorder pedigree confusing me

texts:
This is a pedigree of a family in which bleeder disease, an x-recessive disease, is present. I am asked which marker, A or B, the disease is linked to.
I've asked about this type of problem before: X-recessive disorders and genetic markers
The solution there was the fact that the families were unrelated so the disease being linked with a marker in one family did not correspond to the disease being linked to the same marker in another family.
The answer to this problem is "A". However this is ONE family and there are males in this family with the A marker on their only X-chromosomes who are unaffected and women with two A markers who are also unaffected. How would you explain that? They have the marker for the disease on both alleles but not the disease?


texts: What is the difference between pluripotent and totipotent cells?

texts: Both develop into specialized cells.Then how are they different?


texts:
I understand the difference between the genotype of an organism and the phenotype of an organism, (genotype being the genetic code, phenotype being the physical expression), however I am unsure about what this figure mean when it says "Selection that takes place in the environment is based on the specific phenotype of an organism-its traits, not the underlying genotype".

(misconceptions about evolution)

I thought the genotype controlled the phenotype, so what does the figure mean exactly when its saying that natural selection isn't based on the genotype?

Thank you!


texts:
Why do I see only high temperature advice to kill microorganism, and not low temperature?

Why isn't there any low temperature which kills virus? Are they more resistant to low temperature?


texts:
It is said that erythrocytes, polymorphonuclear leukocytes and brain cannot produce purines. And the reason given as per this site is:

  Human brain tissue has a low level of PRPP glutamyl amidotransferase (reaction Image, Figure 33–2) and hence depends in part on exogenous purines. Erythrocytes and polymorphonuclear leukocytes cannot synthesize 5-phosphoribosylamine (structure III, Figure 33–2) and therefore utilize exogenous purines to form nucleotides.

My question is why do these cells don't produce the required enzymes for the synthesis of purines? What could be the functional significance for such absence?

My attempt : At first I thought that Erythrocytes as such don't have nucleus so they don't need purine synthesis for cell division , but I don't understand why then they need purines from external source( as said in the above site). Also brain cells are neurons and neuroglia, of which former doesn't divide( except in some areas of brain) but they too need purines.
 The later divide but they don't produce required enzyme. Why?

So my questions are:

Why do cells which don't replicate need purines?( May be for formation of Coenzymes , correct me if Iam wrong)
Why do the cells which divide too don't produce required proteins(enzymes)?


texts: determining horizontal gene transfer between two genomes?

texts:
I want to determine if there is horizontal gene transfer between two genomes, in particular I was to use the parametric methods described in wikipedia since I would most likely struggle to understand the phylogenetic methods fully.

The two genomes in mind would be Lactococcus lactis and  Lactobacillus helveticus since they are used in the process of cheese making and therefore would be in close enough proximity/environment to argue for tentative events of HGT. (Correct me if I am way off base here in my line of thought...)

Could I just access representative genomes for each from NCBI and calculate/determine the various genomic signatures that are indicative of HGT via the previously mentioned parametric methods(Nucleotide composition, oligonucleotide spectrum, structural features, etc...)?

Or would the genomes need to be rendered and sequenced from a confirmed source where they are both located/habituated to properly argue for HGT?(In which case I believe NCBI does not have this data readily available?)


texts: I am after some good reference on Soil Microbe Ecology and Biology. I am a biophysicist, and have read the very gentle approach of "Life in the Soil" (James Nardi). Another book I have been recommended is "Soil Microorganisms and Higher Plants: The Classic Text on Living Soils" by Krasil'nikov. This I found very hard going and I was wondering if there was anything more modern on the same subject.


texts: Research on chicken that cannot feel pain

texts:
In was having a conversation about the ethics of vegetarianism, and if it is right to cause pain to other animals.

It is then that I stumbled upon the question, that if, just the way chicken and many other animals have currently been cultured or genetically modified (or by any other means) to have certain desirable qualities (from market and demand perspective) such as the fat content, quality of eggs etc., will it be fine to consume chicken if we also, if possible, raise chicken that do not feel any pain at all (if that is defined, or can we define that?).

I realise that this is not philosophy stackexchange, so I would not ask about the ethics of it.

What I want to ask here is this: is such research taking place (anywhere on earth) to develop breeds of chicken that do not feel pain, if yes I would be thankful to know at least the basics, and if not, do you think it is possible in the near future or what possible approach would you contemplate?


texts:
How does vitamin A deficiency arise?

I am living in a "developed" country, so excuse me if I miss some facts
that are real, and threatening, in other parts of our world.

I heard about https://en.wikipedia.org/wiki/Vitamin_A_deficiency ,
but looking at what foodstuff contains vitamin A or precursors,
I'm at loss how anyone can suffer from vitamin A deficiency.

Obviously, I'm lacking some information here.

One thing that looks particularly misleading is when you are
presented with vitamin A contents of foods, neglecting precursors
like carotenoids that can be easily converted to vitamin A as needed.

As a (sometimes misleading) rule of thumb, I was thinking that most
yellow or orange looking food was prone to contain vitamin A or some
of its precursors.


texts: How would ecology be affected if 100km² of an ocean surface was covered by a floating object?

texts: Assume that we planted floating solar cells on the ocean surfaces. Assume a 100km² solar cell field in the middle of the Pacific Ocean. All of the sunlight will be blocked by them. How would that affect the life in oceans?


texts:
I found a bone in 120 metres under the ground which has nuclear radiation. Can you help me to recognize this bone?

It was found in a clay quarry near Odessa Ukraine.


texts: Help in understanding a sentence about TCR-MHC interaction and immune synapse formation

texts:
T-cell co-stimulatory and co-inhibitory molecules (collectively named co-signaling molecules) play a crucial role in regulating T-cell activation, subset differentiation, effector function and survival. Following recognition of cognate peptide-MHC complexes on antigen-presenting cells by the T-cell receptor, co-signaling receptors co-localize with T-cell receptors at the immune synapse, where they synergize with TCR signaling to promote or inhibit T-cell activation and function.

I'm not sure I understand the second sentence. The language is a little confusing to me. Does it mean that after a TCR binds to a peptide-MHC complex, other TCRs present on the cell gather around that TCR? Does it mean that one TCR can bind more than one peptide-MHC complex (which, as far as I understand, isn't true)?
Here's my paraphrase of this sentence:

Following recognition of a cognate peptide-MHC complex on an antigen-presenting cell by a T-cell receptor, co-signaling receptors co-localize with (other) T-cell receptors at the immune synapse, where they synergize with TCR signaling to promote or inhibit T-cell activation and function.

Is it correct?


texts: Are there differences in cell membrane cholesterol levels between cell types?

texts:
With different cell types, and cell functions, are there distinct levels of cholesterol in each cell type's cell membrane, or do all cell types have a similar amount of cholesterol?

I am assuming certain cell types require different levels of cell membrane stability, and as such, different levels of cholesterol in that cell membrane.


texts:
Well, maybe this is a question more suited to Stack Overflow, but anyway, I am curious, which insect is the one in the logo of the PHP bugs site? Is it an actual insect or just a generic "bug"?

It seems like some kind of Hemiptera for me, probably some kind of "true bug". A quick google search about these insects and I found the Hemiptera suborder Heteroptera, and this critter is probably from this group.

I tried to search by the image in google images, but only found the logo itself, in the same low resolution is the image above (I was not able to find a better version of it). I tried to remove the background from the image then, but still I didn't get any photo of the possible species of this logo.

EDIT: this was the PHP bugs logo up until 24th July 2017; the next day it was changed to another different "bug". This question is about the former logo, not the current one.


texts:
I found a paper estimating the number of species currently living on earth. Now I'm wondering If anybody tried to estimate the number of species that have lived on earth. I'm familiar with problems of "species concepts". But I'm sure, there is at least a number of all known fossils.

EDIT: In contrast to the question How many organisms have ever lived on Earth?
I'm asking for species and not for individuals. The answer to my question can be used to ansewer the queston for the number of organisms. But still, The questions is different.


texts: Computational/mathematical models for predicting phenotype from genotype

texts:
Karr, Sanghvi, et al. (2012) propose a whole-cell computational model for predicting phenotype from genotype in Mycoplasma genitalium. Their model simulates myriad cell processes such as DNA replication, RNA transcription and regulation, protein synthesis, metabolism and cell division at the molecular level over the life-cycle of the organism.

They achieve this by combining many existing mathematical and computational models into one piece of software. The article suggests that this is the first comprehensive whole-cell model at the molecular level in detail. They cite previous molecular-level models for their sub-modules, but don't go on to discuss more coarse-grained genotype-to-phenotype models. Their model is exciting, but the 10 hours of simulation on a top-end computer cluster to follow the life-cycle of a single organism is unreasonable for someone who wants to study evolutionary processes.

Are there prior reasonably accurate computational (or even better, analytic) genotype-to-phenotype models? If there are, what are some of the best coarse-grained genotype-to-phenotype models for commonly studied organisms such as E.Coli?


texts: What is the evolutionary advantage of red-green color blindness?

texts:
Red-green colorblindness seems to make it harder for a hunter-gatherer to see whether a fruit is ripe and thus worth picking.

Is there a reason why selection hasn't completely removed red-green color blindness? Are there circumstances where this trait provides an evolutionary benefit?


texts: How should the interval between serial dilutions be expressed?

texts: The interval between simple dilutions is a constant value added to the preceding dilution to get the next. How should a factor for serial dilutions be mentioned? As there is no common difference between successive serial dilutions, rather a common ratio.


texts:
I am hoping someone can identify the image below

My wife felt a bug bite her and found this in her hair now she's worried that it was a tick.
the photo is at 40X under microscope. I'm guessing it's an arthropod maybe some kind of beetle but I haven't seen anything like this before.


texts:
According to: https://en.wikipedia.org/wiki/Ventilation/perfusion_ratio the ideal V/Q Ratio would be 1.0 because 1 L of blood can hold about 200 mL of oxygen and 1L of humidified air has about 200 mL of oxygen.

However, the actual ventilation/perfusion ratio for the entire lung is described as 0.8. I understand there are regional variations due to gravity, but on the whole, shouldn't the average V/Q ratio be 1?

One thought I had was that because it takes time for O2 to diffuse across the membranes and bind to Hemoglobin, that could explain this loss in efficiency.


texts: Detecting nuclear DNA in suspension of mitochondria

texts: Is there a way to detect nuclear DNA in a suspension of mitochondria extracted from leukocytes? I need to make sure there is no nuclear DNA in the suspension before extracting mtDNA from the mitochondria.


texts: Molecules responsible for reading amino acid language

texts:
The molecules responsible for reading the language of amino acids and nucleotides is:

  RNA polymerase enzyme
  mRNA
  tRNA
  DNA

I don't actually understand what "reading amino acid language" means!
Does saying nucleotides refer to those on the DNA molecule? If so then RNA-polymerase is then responsible for synthesizing mRNA molecules which carries the same genetic code of the amino acids; or is it something else?


texts: What is the name of this tiny creature? It looks like a tiny piece of moving cotton?

texts: By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name?


texts: Possible for bacteria to burst container?

texts:
This is kind of a thought experiment, but are there any conditions under which bacteria could multiply enough to burst the container they're in?

Thoughts so far: Bacteria often need oxygen to multiply, but I believe not always? They need a food source, but perhaps despite that mass already being present they might still have a larger overall volume afterwards?

For the sake of this question, I'd like to be fairly loose with the word "container", i.e. not necessarily something solid glass or even solid for that matter, but at least closed. Perhaps I could have bacteria in a bubble and they could burst that?

Thanks for indulging!


texts: Can sexual selection operate in temperature dependent sex determining organisms?

texts:
Or more broadly, are distinct forms of genetic inheritance (ie. sex chromosomes) needed for sexual selection?

My thinking was that since there are no sex determining loci, there could not be linkage to mutations that are subject to sexual selection.

Given the large sexual dimorphism in crocodiles (wikipedia), I would expect sexual selection is acting in crocodiles, but how are those phenotypes heritable if there are no sex chromosomes?
I know the sexual dimorphism could be due to differences in gene expression, but that still leaves me with a chick-egg problem. What causes the differences in expression?
I'd like to know if there are any studies that have looked at this kind of question.


texts: What is the biological mechanism linking temperature and probability to be infected with a virus?

texts:
It is common knowledge that when you're cold you could get a cold.

What is the mechanism linking temperature and viral infection?


texts:
First question is about why we use primers in PCR. It requires two reasons. I know only one reason though. It is so that DNA polymerase can attach to primer and make a copy of nucleotide from there. But i don't know what is the other reason.
Another question is about why the primer bonds to 3' end of the DNA you want to copy. and explained why. I really have no clue for this one. Plzz help.


texts: What are the causes of abortive initiation?

texts:
I was reading more about DNA transcription, and it mentioned abortive initiation. The article gave no explanation as to why the phenomenon occurs.

The only explanation I can think of is that it is an error in the "machinery" of the RNA polymerase.

Is there any scientific research as to why abortive initiation occurs?


texts: What are ways to compare the "costs" and "gains" of food production systems?

texts:
I'm looking for methodologies to compare the costs a food production requires with the gains it delivers (not in economic terms).

I'm aware of energy returned on investment. Are there other methods used in literature (also including qualitative approaches)?

To be a bit more precise (or rather unprecise?): Costs may include the input of fuel, feed, energy in general or - for me most interesting - the environmental burden to our environment (for example the carbon footprint) while gains should refer to the nutritional output of the product (energy, protein content, other (rare) nutrients).

The purpose is to link (or discuss) the burden of food production chains to their benefits but to find a unit that is quantitative comparable (except the pure energy content) doesn't seem so trivial - so I'm very happy with suggestions how to approach that - in the best case with a link to studies that employed the method.


texts:
Over the past few years I've seen mycelium used as a supplement for various building materials. I was wondering if mycelium could be successfully used as construction material for a sewage pipe.

Furthermore, would this sewage pipe be able to provide any filtering of waste, given the mycelium?

Sources:

mycelium packaging
mycelium plastics
mycelium bricks


texts: Why is SOC medium recommended for transformations?

texts:
In pretty much every transformation protocol I've seen SOC medium is used to grow the bacteria for a short while after the tranformation and before plating.

I've usually substituted LB medium for this step for easy retransformations, but I gather that the SOC medium is supposed to make some difference in efficiency, or else the simpler LB medium would be recommended in the protocols.

Why is SOC medium used for transformations? What difference does substituting with LB medium cause for the transformation efficiency?


texts: Can elephants be allergic to peanuts? If yes, what is the reaction? Does the trunk swell up? I tried googling the issue but the only thing I found was a children's book about Eppie the Elephant. I realize elephants are not particularly fond of peanuts.


texts:
If parasites are organisms that feed on other living organisms, then aren't all pathogens parasites?

I've emphasised on 'feed' because I guess the pathogens just eat us (i.e. take nutrients to reproduce and sustain their lives), right?

But then there's another question.
If, pathogens need us (a host) to survive, then why do they eventually kill us? I mean, why did they evolve to become an organism that exploits their food to the extent that even they, themselves die? Isn't it disadvantageous for pathogens to kill their hosts, because they will eventually die?
Or I'm totally wrong, do those pathogen sustain their lives even when host has died?
Or perhaps they don't care if they, as individual organisms die, because they can survive as an species by infecting other.


texts:
What are the advantages of sexual reproduction over asexual reproduction?

How does variation influence ecological and evolutionary success?


texts: How non-invasive blood glucose concentration measurement work?

texts:
Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the test strip reduces the glucose and the electronics of the glucose meter detect the redox species produced. However, this method is painful and increase the risk of infection.

Photonic sensing technology opens up a new method for non-invasive blood glucose concentration. According to an article of medGadget in 2013 (The link follows http://www.medgadget.com/2013/10/non-invasive-measurement-of-blood-glucose-levels-using-glucotrack-interview.html ), the non-invasive kind was invented. By simply clipping onto the earlobe (without puncturing the skin), the blood glucose concentration could be measured. Does anybody knows the working principle for that? Or, suggest a paper describing that?


texts: Does food continue to stay sequential once it is inside my body?

texts:
I may be very off on many scientific details here, but I'm always all ears.

As far as I understand, any food that is eaten goes to the stomach, gets broken down even further into smaller food molecules, and after a period goes through the intestines where nutrients are absorbed out of this... stomach-output.

Let's say I eat food A sometime, and it's gone down and is now sitting in my stomach, waiting for the stomach to start breaking it down. After a while, I eat food B.

When digestion occurs, is it possible that the stomach only starts breaking down food A's material first before it gets to food B?
Is it possible that food B's output goes into the duodenum before food A's output?

Please help break any of this down if it's obvious I've been living in a cave. Thanks!


texts: Does anybody have an references to share or idea onhow the tumor behaviour changes as it grows from oligometastasis to polymetastasis?

texts: I have looked at the literature and mostly scientist discuss about how a metastatic lesion is formed. But what I am interested to learn is how does a new metastatic lesion develop when there is already several metastatic lesion already present at baseline.


texts: Help me identify this insect found in fishtank

texts: This bug appeared in my fish tank,transparent 6 legged with 3 tail insect. Anyone able to identfy this, please help. Many thanks


texts: How do members of cryptic species know who to mate with?

texts:
According to Wikipedia:

  In biology, a cryptic species complex is a group of species which
  satisfy the biological definition of species—that is, they are
  reproductively isolated from each other—but whose morphology is very
  similar (in some cases virtually identical).

How do members of these species know who to mate with?  Or would they unknowingly mate with incompatible partners?


texts: Why do home-grown fruits tend to taste better than mass-produced consumer fruits?

texts: It is often heard that home-grown fruits and veggies are a lot tastier than the produce found in the supermarket. Although this question may contain a skeptics element in it, it is so often heard there must be at least some biological ground behind it.


texts: Identification of an insect from midwest US

texts:
I have been seeing them more and more frequently indoors.  I am currently in the Midwest United States, weather has been unusually warm for December, and there are many trees nearby. Can someone please help identify this?

The pictures are of the same bug, but from different angles.


texts: How would one model a Neutrophil Extracellular Trap with Hookean Springs?

texts:
This is a question based in biology but involves a good amount of physics.
Given that a Neutrophil Extracellular Trap (N.E.T) behaves like an aggregate of DNA strands with citrullinated Histones and defensins such as Myeloperoxidase and Neutrophil Elastase, and that DNA itself can be modeled as a Hookean spring (maybe with a variable spring "constant"), I thought that it would be possible to model say a 100 uM X 100 uM Neutrophil Extracellular trap as a network of hookean springs.
I think that this would require one to ascertain the length of the DNA strands incorporated into the N.E.T as well as the configuration of these many strands. The configuration will determine whether the spring constants of each DNA strand are additive (for parallel springs).
Is there some approximation of configuration and DNA length I could use to maybe get one cumulative spring constant for a N.E.T of a given size or is more complex notation required? Also the purpose of my asking this question and even modeling a N.E.T as a network of springs is to gauge the compliance and compressive stress that can be generated by the N.E.T.


texts: Selective pressure for reduced rates of growth and maturity in primates

texts:
Humans are somewhat notable for the slow rate at which they grow and reach physical maturity.  Some related primates also take over a decade to reach sexual maturity.

However, many mammals – including ones like horses that grow quite larger than any primates – reach their maximum size in only a few years, so the slow rate of primate growth is not due to simple biologic or metabolic constraints on mammalian growth rates.

Are there any hypothesized selective pressures that might explain the slow physical growth rates of higher primates?


texts: Does bleach destroy RNAse activity, and if so, how does it do it?

texts:
I am working with RNA samples, and I'm trying to be very careful about RNAse contamination.

I have some questions about bleach, though. Some people say that a solution of bleach is enough to destroy RNAse activity, but is it really? How does it do it?

I'm not sure if wiping the surface using a solution of bleach would be enough to kill RNAse activity, or if it is necessary to use products such as RNAseZap or RNAseAway.


texts:
How can a placenta turn hostile to the mother or fetus ?
What are the abnormalities found during placental delivery ?


texts:
I keep reading about how primers are useful in pcr -- they allow you to select a specific dna region. Similarly, in NGS or Sanger sequencing they give you a starting point. The primers I see are about 20-30 bases long.

However, how were the first primers developed? Somewhere, someone needed to come up with a 20-base sequence that bound to a specific part. Aren't there 4^20 such combinations? That's a lot of potential options to test.

How was that done?


texts: Cell-autonomous viral defense involving oxidative burst?

texts: I'm looking for a mechanism by which a cell detects a virus (probably a retrovirus) within itself, then triggers an oxidative burst in response. This should all happen within the cell itself, independent of any immune-specific cells outside. Ultimately interested in humans, but any pointers whatsoever would help.


texts: How does the cornea breathe during sleep?

texts: The cornea is not supplied with blood vessels and so exchanges gases directly with the atmosphere. So how does it breathe during sleep when our eyes are closed?


texts: How do both autotrophic and heterotrophic successions end up having Gross Production = Respiration?

texts:
I was reading Information theory by Eleith, Odum and Golley  from different sources, one of which was Funfamentals of ecology by Odum:

... autogenic succession usually begins with an unbalanced community metabolism, where gross production, P, is either greater than or less than community respiration, R, and proceeds towards a more balanced condition, where P=R. The rate of biomass production (B/P ) increases during sucession until a stabilised system is achieved, in which a maximum of biomass (or high information content) and symbiosis between organisms are maintained per unit of available energy flow.
The succession begins with P>R in autotrophic sucession and P<R in heterotrophic sucession.

I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post.


texts: Are there any theories using thermodynamics/statistical mechanics or information theory principles to modelling in ecology?

texts:
So far, I've only known one: the MaxEnt theory. It uses the maximum information entropy developed by information theorist, which in turn inspired by the thermodynamics from physics, to predict the number of organism in an area. This theory is developed by John Harte.
You can read about this theory in Quanta Magazine.

I also know the book Towards the Thermodynamics Theory for Ecological Systems, written by Jørgensen and Svirezhev.

I find it hard to find another theory similar with the two theories above. Do you know any theories using the thermodynamics or information principles to modelling in ecology?

I have opened a reddit discussion about this.


texts: Can you answer Ray Comfort's question on Biological Evolution?

texts:
https://www.youtube.com/watch?v=U0u3-2CGOMQ

There's this video on Youtube about biological Evolution that has gone viral. I'll paste it above for your convenience.

To cut to the chase, Ray Comfort asks this question repeatedly to various people, and I guess he never got an answer or a good answer. The question is:

Can you think of any observable evidence for Darwinian Evolution where there is a change of kind?

By change of kind, I assume Comfort wants observable evidence of one species/kind morphing into a new or different kind/species.

How would you answer this challenge?


texts:
I spotted this rodent in Winnipeg, Manitoba, Canada on September 6, 2020.
It is about 10 inches long.

What is it?


texts: What is the exact chemical composition of human body?

texts:
I've just watched Breaking Bad Season 01 Episode 03. In that Walter gives the chemical composition of human body. The conversation is as follows

  Walter White: Let's break it down. Hydrogen. What does that give us?

  Gretchen Schwartz: We're looking at 63%.

  Walter White: Sixty-three, that is a big bite. My next step's gotta be
  oxygen.

  Gretchen Schwartz: Oxygen, 26%.

  Walter White: Twenty-six. There you have your water.

  Gretchen Schwartz: Carbon, 9%.

  Walter White: Carbon, 9.

  Gretchen Schwartz: For a total of 98%.

  Walter White: Right.

  Gretchen Schwartz: Nitrogen, 1.25%.

  Walter White: One-point-two-five.

  Gretchen Schwartz: That brings you to 99 and a quarter. Which only
  leaves you with the trace elements down where the magic happens.

  Walter White: Oh, wait a minute. What about calcium? Calcium's not a
  trace. Got a whole skeleton to account for.

  Gretchen Schwartz: You would think, right? Calcium's only 0.25%.

  Walter White: What? That low? Seriously? Damn, I never would've
  thought that. Okay, so where does iron fit in.

  Gretchen Schwartz: Iron. 0.00004%

  Walter White: What? You can't have hemoglobin without iron.

  Gretchen Schwartz: Apparently, it don't take take much. No doubt. Go
  figure.

  Walter White: Sodium.

  Gretchen Schwartz: Sodium, 0.04%. Phosphorus, 0.19%.

  Walter White: Point-one-nine. There we go. So the whole thing adds up
  to... 99.888042%. We are 0.111958%. Shy.

  Gretchen Schwartz: Supposedly that's everything.

  Walter White: Yeah? I don't know, it just... it seems like something's
  missing, doesn't it? There's got to be more to a human being than
  that.

  Gretchen Schwartz: What about the soul?

  Walter White: The soul? There's nothing but chemistry here.

When I searched for it, Wikipedia has something different.

Which one is correct?


texts: It is in Texas(Month: May). Are these flying ants?termites? or Cicada Killers?


texts:
Early in the epidemic, Chinese researchers (Jian Lu, et al,) reported in the National Science Review earlier this month that there was an aggressive more virulent L strain compared to the older S strain of the virus. Of the 103 viral genomes they scoured, 70% were of the L-type variant using phylodynamic analysis of samples taken during the earliest phase of the outbreak that began in Wuhan late last year.
But subsequent later samples taken later in the course of the epidemic were mostly of the S strain.
Peer review by researchers at other institutions have recently called this study into question.

Does anyone know where this stands currently? Has an aggressive L strain been confirmed? Do current rRT-PCR tests make any distinctions between L and S strains?


texts:
As far as I know there is no absolute time measurement (one that would measure time in a non-environment-dependent fashion) in any life form. Only such time measurements exist, which are dependent upon cyclic changes like the strength of the sunlight, heat, amount of water, etc. (In case this assumption of mine is false, than please answer it in mind of life forms which in deed have only relative)

Theoretically, if we could change everything a given life form is dependent upon, could we increase it's entire lifespan?

For example if we were to put a plant inside a manually controllable environment and slow down the day/night cycle to it's third, maybe even decrease air pressure and the strength of gravity(thus eliminating any problem that might arise from the actual transport of water and the solution of organic matters produced in photosynthesizing cells), change (even though I'm not sure if this could be physically possible at all, but my whole question is theoretical, thus it should not cause a problem) the adhesion/cohesion as well (so the speed of transports in the cells would change accordingly) and change other, (for me) unthinkable aspects that, for example, regulates the time between cell divisions, would it live for longer?

Even if we could not change every aspect that regulates a given life form's working, changing many could we (although this time not linearly) increase it's actual lifespan?


texts: Where are interneurons in Autonomic Nervous System?

texts:
According to  the following, it implies that preganglionic neurons are interneurons.

  Interneuron called preganglionic neuron whose cell body is situated in the "intermediolateral" column of spinal cord( also called 'lateral column').1

From this:

  The interneuron (connector neuron) of somatic system has cell body in the dorsal horn and terminates in the ventral horn, while that of ANS has cell body in the intermediolateral horn and terminates in the autonomic ganglia....In the ANS, there are two efferent neuron chains between CNS and the effector organ: first efferent neuron (pre-ganglionic neuron) has its cell body in CNS while the second efferent neuron (post-ganglionic neuron) has its cell body out-side the CNS in the ganglion.

But this source implies quite opposite:

  The spinal sympathetic interneurons that most directly influence the activity of sympathetic preganglionic neurons after spinal cord injury....

So which one is correct?


texts:
What is the roughly the distribution of the various synaptic connections in the brain.

Consider the following types:

axoaxonic synapse between the axon of one neuron and the axon of another neuron.
axodendritic synapse between the axon of one neuron and the dendrites of another.
axodendrosomatic synapse between a neuron's axon and the dendrites and body of another.
axosomatic synapse between the axon of one neuron and the body of another.
dendrodendritic synapse from a dendrite of one cell to a dendrite of another.

I know that the axodendritic synapse is the most prevalent, but what is order of the others? Are there any sources for this (couldn't find this anywhere). Specifically, rough percentages of the distribution (amount) of these synaptic connections in the nervous system would be very helpful.