texts: Did baby bird hair and mammalian hair convergently evolve?

texts:
Chicks (baby of chickens) and ducklings seem to have fine hairs, at least something that look like hairs to me. Most mammals have hairs, but reptiles, fish, or other animal groups do not have hairs as far as I know.

I have looked up the tree of evolution, and it looks like this.

So, the tortoises, crocodiles (I do not know what lepidosauria means but I guess it is reptiles other than the aforementioned), and birds diverged after their common ancestor was split from the common ancestor of mammals.

Since none of the tortoises, lepidosauria, or crocodiles have hairs now, does this mean that the hair of birds and mammalian hair is an example of convergent evolution? Or did these other taxa lose hair during evolution?


texts: Do DNA footprints vanish in generations?

texts:
Consider humans (or really any creature with sufficiently complex set of genes).  If person $A_0$ has an offspring, say $A_1$, we can without a doubt find markers in $A_1$ that we can definitely say indicate that $A_1$ is the progeny of $A_0$.  Likewise, for any generation $n$ we can say that $A_{n+1}$ has markers that indicate that generation $A_n$ is their parent.  Presumably (and maybe this is where I'm heavily mistaken), as $n$ grows large there are fewer "direct signs" that $A_n$ has $A_0$ in their ancestry.  I mention "direct signs" (although this isn't an official term) because obviously if one can prove $A_{n-1}$ is the parent generation to $A_n$ and $A_{n-2}$ proceeds $A_{n-1}$ and so on ... then one can deduce the relation between $A_0$ and $A_n$.  That's not my point.  My question is this:  Do the genes of $A_0$ "dilute" so that after so many generations it is possible or probable that none of the genes from $A_0$ are present in $A_n$ for some large $n$ (where by "none" I mean "no genes that give us a high warrant for believing $A_n$ is related to $A_0$ in the absence of evidence about $A_j$ for $2\le j \le n-1$").  Obviously if $A_0$ is human and $A_n$ is human then they share a great deal of their genes with one another (something like $99.99\%$)

If there is such an $n$, how large does $n$ need to be so that say $90\%$ of what makes $A_0$ unique is no longer present in $A_n$ (with a high probability of confidence), what about $95\%$ no longer being present, or $99\%?$

Please let me know if my question isn't sufficiently clear (I'm trying to convey the heart of my question, even if it isn't perfectly worded).


texts: protein size range for ultrafiltration or nanofiltration

texts:
I am hoping to concentrate mixed proteins in homogenized leafy vegetables such as kale, spinach etc (after removing pulp and fibers) as a first step in further investigations (second step using size exclusion to isolate frations), but am unsure what pore size is appropriate for ultrafiltration membrane as I do not know the dalton range of the mixture.

Is there a typical range of protein molecular sizes in Daltons found in plant matter?

Would appreciate any pointers.


texts: Calculation of extinction coeffcient of GFP

texts: I want to convert the absorption of a protein into concentration. Hence ı need to calculate the extinction coefficient of the protein (GFP). ı found the formula (nTrp)5500+(nTyr)1490 on the internet but not able to use it since ı dont understand what n in front of the amino acids stand for and how ı reach to the n value


texts: How can we differentiate between respiration and breathing?

texts: I am a student of 10th grade, and I eagerly want to learn biology. What is the difference between respiration and breathing?


texts: Sextuplet corn (Zea mays with branched ear)

texts:
In 2019 I planted some sweet corn next to some Hopi blue flint type corn. Of course my mistake was apparent once I started to see the ears. The closer the two types were to each other, the more they were mixed. So this year, not realizing what might happen, I planted the solid blue seeds that I had saved. I don't know much about corn, clearly, and assumed that if I planted blue seeds, I'd get all blue corn. Not the case. Most was all kinds of different colors, shapes, including some kernels that were clearly sweet corn, with most being a field corn, some with a dent, most without. Then some plants had some nice large ears of large blue kernels.
Okay, so that is just the backstory in case it will help. I ended up with this one 'cob' that is actually 6 small cobs all on one stem. Very bizarre, and I can find nothing like this online. I am curious if anyone can tell me how this happened, and perhaps if planting those same seeds would result in more of this. I took a video to get the best look of this oddity. https://youtu.be/xIAYaRwgQ-k


texts:
From my understanding, single celled organisms have been seen avoiding, and chasing, potential food or other organisms.

How do they accomplish this? They do not have eyes or ears or a nervous system. My understanding is that chemical reactions are involved somehow.

How do single-celled predators chase other cells? What happens on a chemical level?

Edit:To help keep a more constrained question, the single-celled organism I am considering is Paramecium


texts: how do we prevent restriction enzyme of bacteria to cut and destroy our new recombinant?

texts: Based on cloning principle, the new DNA recombinant will be introduced to host cells, commonly bacteria, how do we prevent restriction enzyme of bacteria to cut and destroy our new recombinant ?


texts: I always thought the silver colour specific to nerves was due to the myelin sheaths, but I've observed that unmyelinated C fibres display that same silvery appearance. Where does this colour come from? And can you distinguish myelinated from unmyelinated fibre bundles with the naked eye from their colour?


texts: Which organs/tissues are defined as "peripheral organs/tissues"

texts:
In the following paper [1], I encountered one term "peripheral organs". Literally, based on my understanding, it should be related to the organs/tissues, such as skin, hair and ear in the human, and wing, antenna and leg in the insect. However, in reference [1], fat body, oviduct and hemocytes are listed as peripheral organs. Is there specific definition of "peripheral organ/tissue"?

Thank you!

[1] Verlinden, H., et al. (2010). "The role of octopamine in locusts and other arthropods." J Insect Physiol 56(8): 854-867.


texts: What are these bugs skittering about the kitchen sink?

texts:
I found a bunch of these around a kitchen sink in an apartment building in Toronto, Canada, in late October, 2019.

The bugs vary in size, but are all very tiny, less than one millimeter (the photos were taken with a macro lens, and still barely captured them).

They move very fast when they detect light changes, and hide in the crevices around the sink.

They die very easily when squashed.

Edit: Managed to shoot a larger, more photogenic specimen.


texts: What is the probability of an XX female or XY male?

texts:
Homework question

  In genetics the chance of having a male or female is 50% for male and 50% for female. Using factorial method and Punnett Square prove or disprove the claim.

My answer

Using the factorial method:

P        XY  * XX

F1     XX  XX  XY  XY

Punnett Square method:

+-----+----+
| XX  | XY |
+-----+----+
| XX  | XY |
+-----+----+

So yes, the claim is right 50% for male and 50% for female.

I want to make sure that I solved the problem correctly using the two methods (factorial and Punnett).


texts: How to convert PDB file of Amino Acids to rotamer tuples list of all AAs instances

texts:
Either by Python command, or via specific application (like Chimera) publicly available. Please provide example or link to one of.

I have to detect AA location within MAP (density) 3D matrix. And to verify with PDB format (which models same 3D structure). Each AA may have different rotamer (aka 3 angles usually used to describe AA exact position related to carbon C_alpha atom (the atom which AA side chain exits from). To justify inaccuracies - I need to show that (among other reasons) - inaccuracy is caused since not all possible rotamers existed in my training set (I use machine learning classification to decide what AA is it, and where it stands within cryo- EM scan).


texts: Can vaccines move from person to person?

texts: Can someone who has been given a vaccine "infect" another person with the virus used in that vaccine? For example, let's say Bill is vaccinated against tuberculosis. If Frank is exposed to Bill, is there a chance he could "catch" the tuberculosis vaccine, and become immune?


texts:
Does our DNA adapt by human lifetime? Or do we have the same genetic information from birth to death?
I mean: What is usually called "evolution" means "natural selection" like this:
http://www.youtube.com/watch?v=hOfRN0KihOU&list=UUsXVk37bltHxD1rDPwtNM8Q
-stronger animals have more descendants, so they make bigger percent of strong animals.
But does evolution work by some primitive genetics-engineering too? Thank you.


texts: Possible calculations with temperature, humidity, images and VIS spectrum of a plant in an Integrating sphere

texts:
I am currently working on a project which involves growing some plants in a integrating sphere made of foam. I have added temperature, humidity and soil moisture sensors as well as a Spectrometer (350 - 800nm) and a webcam which takes images of the plant every 30 minutes.

I thought of calculating the LAI (Leaf area index) from the webcam images.

Does anyone have any other suggestions/ideas on what I could calculate with the given data from these sensors?


texts: What specifically allows alpha-complementation in beta-galactosidase?

texts:
I'm familiar with the use of alpha-complementation of beta-galactosidase with the pUC alpha-peptide and the M15 lacZ gene product, and would like to hypothetically apply alpha-complementation in other settings with different enzymes. I do have a few questions, but hopefully they are similar enough to all be answered here.

What specifically allows for the non-covalent association between both truncated protein products to form a functional beta-galactosidase? How is beta-galactosidase unique in that separating it into two portions still yields a functional enzyme (in other words, why wouldn't other enzymes remain functional if I split them)?
What other proteins, if any, have been engineered to perform similar alpha-complementation? What steps were taken to accomplish this?


texts: Why are humans so variable in appearance

texts:
Most animals look almost identical to their peers. To distinguish lions we record the spots on their face; with whales we look at the blemishes on their tail or flukes. In other words, we have to try hard to distinguish one lion from another.

In the case of dogs, we have created many different looking breeds - but within each breed they look the same: one poodle looks very much like the next one.

On the other hand, with humans we have not only the different races (cf. dog breeds), but even within one race no two people are alike. And, not only are the faces different, the body shapes vary equally much. We use face and body shape (and voice) to recognise each other. Most other animals use smell or sound.

I thought the reason for our uniqueness might be that, with civilisation, we are not constrained us to look the same. However, even in hunter-gatherer tribes each person looks different from every other one.

So what is it in human evolution that made us unique in this regard? And, are we unique? I cannot think of any other species with as much variation as ours, but are there others?


texts: What decides whether an ulcer/chancre is painful or painless?

texts:
In sexually transmitted infections, it is important to differentiate a painful ulcer from a painless one. This is because painless ulcers are seen in the chancre of primary syphilis while painful tender ones are seen in Herpes and though rare, in chancroid (H. ducreyi).

I can guess that it must be due to peripheral nerves, but how does this happen?


texts: What kind of cell has the most different receptors?

texts: All hormones and neurotransmittors has their own receptor. Now some of the cells has a few different receptors but others has many sorts of receptors. So what are the most receptive cells? Are that the some braincells?


texts: Can GENESIS simulation software be adapted to other types of tissues?

texts: GENESIS simulation software http://genesis-sim.org/ is designed for neurobiological systems and it is able to inculude in the simulation the different resolution levels - starting from the molecular interaction and ending with neuronal interaction. My question is - can GENESIS be applied to other tissues, are there efforts to do this and what kind of adaptations should be made? I guess that GENESIS is already capable to include full diversity of the molecular interaction patterns that are common to all cells. But some tuning is necessary for models at the cellular and multi-cell level? I guess that there is lack of dedicated GENESIS-level software for other tissues and systems.


texts: What is allele-specific gene expression?

texts: I read somewhere that the two different alleles which we (and other species) inherit from our parents are not expressed equally in our cells. Which genes show allele-specific expression? How and why?


texts: Is my Y-chromosome the same at 78 as it was at 18?


texts: Red Blood Cell Size Vs White Blood Cell Size

texts: I have just found out that white blood cells are larger than red blood cells and now I'm confused due to something I learnt in class. Basically, I was taught that there were spaces between the endothelial cells lining the capillary and these spaces allow white blood cells to escape and enter infected tissues to help clear out the infection. Why don't the red blood cells escape then if they are smaller than white blood cells they should fit through the spaces as well right?


texts: Is the Amazon forest O2 and CO2 neutral?

texts:
In these days, we receive a lot of concerning news about the Amazon burning. Recently, I came across widespread claims about the production of O2   and the absorption of CO2 by the Amazon forest, something known as "carbon dioxide in, oxygen out". However, I also found claims that the Amazon ecosystem uses up all the oxygen it produces, and that it is a stable carbon sink, i.e. it acts like a carbon storage system, not as a sponge for carbon.

What are the real facts about oxygen and carbon dioxyde dynamics in the Amazon forest? I'd intuitively say that the second hypothesis is stronger, but I'd like to have a confirmation backed by some papers.


texts: Effect of single-gene overexpression in the cell's response

texts:
Which are the factors that modify the overall gene differential expression by introducing a vector for single-gene overexpression?

If you overexpress a gene for a protein involved in signal transduction (e.g., a kinase, scaffold, or receptor) by vector cell transfection, then you overdrive the cell using this signaling pathway, it's useful to isolate the pathway and study them.

Is there any way to modify the overall gene expression or cell differential expression pattern by gene transfection? I think this would work if you delivered a gene for overexpression in proteins involved for RNA processing (e.g., splicing, ribosomal proteins, etc.), RNA transcription (e.g., TFs) or protein translation.


texts: Advantage of GCPRs over RTKs or other receptor protein kinases

texts:
My book lists two important differences between GCPRs and receptor protein kinases:

GCPRs do not directly activate a signal transduction pathway. It only does so indirectly, via a G protein. On the other hand, RTKs directly activate a signal transduction pathway, bypassing the mediation of a G protein. (Any G proteins involved with RTKs act as relay molecules in  themselves and are part of the signal transduction pathway.)
GCPRs only activate one signal transduction pathway, while RTKs can activate many pathways.

From what I can tell, receptor protein kinases are faster and more versatile than GPCRs. They do not require as many intermediate steps and can activate many pathways at once. However, GPCRs make up the most largest class of ligand receptors in human cells. This leads me to think there is a great advantage GPCRs have over RTKs that I’m not seeing.

If RTKs are more advantageous than GPCRs, why are there more GPCRs than RTKs?


texts: A tool to get annotation features by position in the reference genome

texts:
Previously, when I needed to find a genomic feature (promoter, CDS, repeat etc) that underwent mutation (SNP) I used my own scripts to load an annotation file, parse it, map the SNP's position and output the sequence of the feature. Now that I'm moving from microbes to mammals with huge annotations, introns/exons and huge genomes, my scripts don't work that well and I'm sort of lazy to optimize the code or rewrite it in a faster language, since I'm sure there should be some prominent tools for the task. That's it, could you recommend me some tools that do the following:

Given a reference genome, annotation and a VCF (or similar variant file) match the SNPs to genomic features in the annotation
Output the entire feature that underwent mutation, e.g. if the SNP happened in a protein-coding gene, I need to have the entire protein-coding sequence not just an exon/intron.

Thanks in advance.


texts: Is it possible to create a biological radio?

texts: If someone had taken the genome for a basic single or multi-celled organism, and had the understanding of genetic code to write his own program, is it possible on a fundamental level to create the organelles necessary to emit an electromagnetic signal at a frequency that isn't widely used by modern day electronics (noise concerns)?


texts: What allows diverse ecology to thrive despite forces reducing species diversity?

texts:
Ecology and business are a useful model for understanding one another. One species fills a niche until it is outcompeted by another just as one business fills a niche until it is outcompeted by another. Businesses adopt successful strategies and traits from others, roughly akin to horizontal gene transfer, and fail should they become no longer able to compete.
The breakdown of this duality reveals interesting questions about differences between the two where one would expect similarities. One big example of this, and the topic of this question, concerns the trend of de-diversification in business. Over time, competitive industries tend toward a decrease in number of companies (species) filling a niche, with major shocks (like COVID-19) tending to cause smaller businesses to go extinct, and the strengthening of bigger players. Once a powerful oligopoly is established, it is almost impossible to overturn.
Yet in Earth's history, there have been countless major and minor extinction events, and countless highly successful species dominant in their niche that have been successfully displaced by smaller, newer competitors. Why is it that new competitors can compete with entrenched incumbents in biology, maintaining species diversity in biology where it fails in business?


texts: Examples of real biological applications of the Keller-Segel system

texts:
I am working on a model of aggregation behavior modeled with the Keller-Segel PDE system. I recently gave a talk on this and was asked what other examples there were of the Keller-Segel system. Since this is an obvious question, I was embarrassed to have no example other than my model and the aggregation of cellular slime molds (the application for which the Keller-Segel model was originally devloped). So I did some googling and came up with bupkis. There are hundreds of papers about the system by mathematicians, but I failed to find any other biological examples.
What about it? Is the Keller-Segel model mostly just a mathematical curiosity, or is it a model with many real applications to biology?


texts: Can any systems biology model be complete?

texts:
In systems biology, models identify the primary actors in the body system, but can any model which does not include all secondary actors be said to be complete?

The current sysbio paradigm is to identify and study biological subsystems. However systems and interactions are subtle and numerous, and no scientist will be able to identify and describe, by hand, how the system works in its entirety. What attempts have there been to model a complete ecological system of internal chemical dynamics?


texts: How do I get recombinant proteins into the nucleus of mammal cells?

texts:
I know that there are Nuclear Localisation Sequencenes (NLS). They can be taken from endogenous or viral proteins and fused to the N or C terminus of my recombinant protein.

Which is the best one? Which the best short one (so that it can be more easily added with a Primer)? Should it be attached to the N or the C terminus?
Do they influence expression?

I have heard that size does matter (Too large wont fit through the nuclear pore, too smalll will diffuse out again). What is the range of protein sizes that can be targeted efficiently?


texts: Where to download confier (pine) or A. thaliana annotated reference RNA transcriptomes in full .gbk (GeneBank) format?


texts: Why are flies not scared when landing on a monitor with changing graphics?

texts:
I have been wondering why would insects in general, not be scared when important changes happen on your monitor where they have landed...

If you move even just a finger, they are scared to death and fly away, but anything on my monitor and they remain completely placid.


texts:
The Trilobite is probably one of the most successful created which evolved in the cambrian explosion.

Though many sources stated the Opabinia has been hunting for Trilobites, this has yet been proven wrong.

Due to my research I haven't found much more animals in the Cambrian age that grow larger than Trilobites or Opabinias - so I do wonder why did Trilobites evolve such a powerful full-body armor when they're have been no clear natural enemies.


texts: Scaling of Ca2+/biochemical signals with dendritic spine size?

texts: I am looking for references that discuss the scaling of biochemical signals in dendritic spines with spine size/synaptic strength. A recent paper (Walker et al. 2017) reports attenuation of NMDA receptor Ca2+ signal with increasing spine size, consistent with a scenario where increase in synaptic efficacy (AMPAR/NMDAR conductance) is overcompensated by spine volume expansion. However, it is not clear to me if this trend is also reflected in the activation of downstream biochemical signals like calmodulin (CaM) or CaM-dependent enzymes. This relates to the issue of how the threshold for plasticity might be regulated as a function of synapse strength/spine size. Would be very interested in knowing if this kind of data has been reported in the literature.


texts: How do other primates treat their fingernails?

texts:
Do all primates have to trim their fingernails in some way, or do some primates' fingernails wear off through natural use?

Also, is constant nail growth common to all primates?


texts: Can a miRNA be upregulated and downregulated in the same disease

texts:
I am computational guy and hence apologies if the question is silly.

Can the same miRNA show upregulation and downregulation in the same disease? (Not in the same experiment, though). For e.g. can there be a instance of miRNA hsa-miR-21 being upregulated in a disease glioblastoma in 1 study and in another study there is an occurrence of hsa-miR-21 being down-regulated in glioblastoma. Is this possible?

As an example, I found:
hsa-miR-345 -> overexpression in pancreatic cancer (PMID: 16966691) and,
hsa-miR-345 -> downregulation in pancreatic cancer (PMID: 17149698)

Any pointers would be appreciated.


texts: Why do plants' leaves become enlarged in low light areas?

texts: Why do almost all plants in shade have a smaller stem structure and larger leaf than that same species grown in a well lit, sunny area?


texts: What is the most critical step of plasmid purification?

texts: During the process of plasmid purification and quantification, which step is the most critical to the success of the process?


texts: Function and Characterization of poly(T) and (AT)

texts:
I came across three terms; "poly(T)45", "poly(A)45" and "(AT)15". Can anyone explain what they are? I know the number refers to strand length, possibly poly-T is a strand of thymine monomers and that ss(AT)15 refers to a 30-base (dAdT). I assume this refers to a single that looks like this;
dAdT-dAdT-dAdT...repeated 15 times.
In that case, what is the d?


texts: Binding BSA to silver surface via large difference in isoelectric points of the two materials

texts:
I would like to bind BSA to a silver surface so that I can utilize plasmonic sensing to detect the BSA. There seems to be two methods of doing this: 1) to rely on electrostatic forces or 2) to form a covalent bond. The former seems to be the easier route, especially for someone like me who does not have a background in chemistry/biology.
So I found a paper (https://doi.org/10.1016/0021-9797(91)90121-N), which has been cited 54 times, that determined a silver (oxide) surface has an isoelectric point (iP) of ~10 pH. So this should mean that it has a positive charge when a neutral pH solution covers the surface. In other literature BSA has been shown to have an iP of pH 4-5, so it should become negatively charged in a neutral pH solution. So the BSA should bond to the silver surface in a neutral solution, correct?
The reason I ask is two-fold. First, I found a more recent paper (https://doi.org/10.1021/am400909g) that has a conflicting value for the iP of a silver film (~3 pH). Second, I found a paper (https://doi.org/10.1016/j.vibspec.2003.09.003) were the authors adsorbed BSA onto silver films, but with the intermediate step of applying 2-mercaptoethanesulphonate to the silver surface. Why the need for this if the silver should attract the BSA electrostatically?
In addition, if BSA bonding to silver were to work in this way, am I correct in thinking that a neutral solvent such as phosphate buffered saline would hinder the electrostatic bonding process because the positive and negative ions from the salt solution would bond to the respectively charged molecules and neutralize the charge?


texts:
I live in Auckland New Zealand. I have been growing Chia seeds in bowls with just water. I noticed after a couple of weeks, these white / transparent worms appeared in the bowl. It seemed that they came out of nowhere? I have seen them crawling in my bathroom before. And the really big ones can get up to a 2-3 cm, so they can't possibly be drain fly larvae as they can grow to a few cm? I also did not see any drain flies nearby. I wonder what type of worm are they? I hope they don't come from tape water, because I have been drinking from it directly.

[EDIT] - Photo of the worm in bigger size (~1.5cm):


texts:
I have read the following sentence:

  Because this oxygenated hemoglobin is unaffected by magnetic fields,
  the response RF signal returned to the fMRI scanner is stronger when
  there is more brain activity and therefore more oxygenated hemoglobin
  in that brain tissue.

Oxygenated hemoglobin does not react to magnetic fields, while deoxygenated hemoglobin does. So in my view, if there is more brain activity and therefore more oxygenated hemoglobin, the signal should be weaker because the oxygenated hemoglobin does not react to the magnetic field? Why is it the other way around?


texts:
I think it's pith, but here (non-english country) many chef suggest orange's vascular veins which look "fibrous" and have similar translated word with "fiber" itself.
Please enlighten me which?


texts: How long does the Ebola virus remain infectious on contaminated items or surfaces?

texts: I'm sure there will be variation depending on what the contaminated item or surface is made of - linens, I could imagine, would remain dangerous for longer than a door-knob. But if the items are not decontaminated in some way, how long can the virus survive outside a host?


texts:
Im trying to find out what this is, see image below.

Im thinking these are either some insect eggs or some sort of mosslike plant.
The substance is stuck to a steel pillar, outside, about 5 feet above the ground.
The substance is found in the Netherlands in a wet meadow area.

The substance has multiple tiny cells or eggs, seems to be only 1 layer thick and has a soft/smooth feel to it.

Excuse me for the bad picture, my camera would not focus better because of the reflective surface of the pillar.


texts: Why does the refractory period of neurons only allow signals to pass in one direction?

texts: My textbook states that the advantages of the refractory period is that it means that action potentials are discrete and also that it results in signals only being able to pass one way,  but provides no explanation. Could anyone explain why this is?


texts: difference between motifs, domains, patterns, signatures and profiles

texts:
I can't get clear the difference between those terms, I see them a lot while browsing on Prosite, Pfam, Expasy e.t.c.
However, I can find documentation about them, but It still not clear what the difference is between those terms. I think it's something like:

motifs: Short residu stretch, not an indication of homology
domain: Could contain motifs, howevever most of the time is bigger, it can be used to identify homology if two proteins share a domain.

However I can't fit the patterns and profiles in this list.


texts: Who and when was the first human diagnosed with hemophilia, or considered a carrier?

texts: The earliest case I can find is Queen Victoria of England, who ruled from 1837-1901. Is this the first hemophilia case on record?


texts: Why are antibacterial body soaps uncommon?

texts: If body odor is caused by bacteria, and antibacterial soap kills bacteria, why aren't antibacterial body soaps hailed as the holy grail of getting rid of body odor? I can only find hand soap that is antibacterial.


texts: How was 2019-nCoV (Wuhan coronavirus) identified so quickly?

texts:
It seems that from the first few cases to identifying 2019-nCoV as a new disease happened very quickly. How were they able to identify this as a new disease and not an outbreak of a previously known but rare disease so quickly? Side question: How many patients were needed to identify this new strain of coronavirus?

If this question can be answered in the generic case as well (how do any new diseases get identified quickly), that would be good too!


texts:
I have just learnt about neurons. I wonder why neurons have only one axon. Can they transmit nerve impulses faster and more rapidly when they have more axons? Does having more axons help in coordination?

Could anyone tell me why neurons have only one axon?


texts:
Speciation can occur by polyploidy. My understanding of the process is as follows:

'polyploidy is when the number of chromosomes in an organism's cell doubles. This means that the organism has more chromosomes than other individuals of the same species, meaning it cannot mate with other individuals. The polyploidy organism then evolves, eventually leading to it becoming a separate species'.

I realise this may not be exactly correct. Is someone able to provide a better description of speciation by polyploidy?


texts: Do Archaea have membrane-bound organelles?

texts:
From Campbell Ch. 6 Intro to the Cell,

Which of the following statements concerning bacteria and archaea cells is correct?

A) Archaea cells contain small membrane-enclosed organelles; bacteria do not.

B) Archaea cells contain a membrane-bound nucleus; bacteria do not.

C) DNA is present in both archaea cells and bacteria cells.

D) DNA is present in the mitochondria of both bacteria and archaea cells.

(A) is correct. My logic was that Archaea and Bacteria were originally from the same family as they are prokaryotes with membrane-less organelles. Is this thinking correct? If not, where am I wrong?


texts: If we can make magic bullets that are basically artificial antibodies, why has a cure for cancer not yet been developed?

texts:
So protonsil and salvarsan 606 where both used as the first magic bullets in the modern period of medicine in the 1900s. However, if we can create artificial antibodies that target specific diseases how have we not come up with a cure for cancer? It seems it shouldn't be that difficult. But if we COULD create artificial antibodies that target cancerous cells would we be able to do it effectively without the drug having any bad or quite noticeable side effects on the body?

By the looks of it chemotherapy is the closest we have gotten so far in chemical drugs, but it does have some nasty side effects.

I was aware of 5 of the approved treatments.
However each type of cancer is similar but different, would it be ever possible to create a generic treatment?

Edit: I have found something interesting, scientist have come across a way to change the antigen on a cell however it is not fully understood.


texts: What is the need for lobules in (human) testicles?

texts: While I was studying the reproductive system, the question popped up in my mind. Each testicle has lobules formed out of the tunica albuginea, in which there exist seminiferous tubules. Why is the testicle divided in these lobules? What's the point? Why isn't it one single big cavity?


texts: Fruit Chafer found in Zambezi valley at Victoria Falls on the Zambia/Zimbabwe border


texts: Do females living on mountains have more RBCs than a normal male

texts:
I got this doubt when I was studying about haematocrit value. According to my NCERT textbook males have greater number of RBCs than females. But who will have more RBCs when comparing a normal male and a female who lives at a higher altitude?

*edit

the magnitude of altitude would be less than 8,586 m (28,169 ft) as the woman I know is not exactly at the top summit of Kanchenjunga so what would be the answer then?


texts:
I am working on a project which involves bio-marker discovery in neuro-developmental disorders. I have an akta-prime FPLC instrument in my lab but I do not know how to use it.

According to theory, plasma, or serum, normally contains numerous proteins of high molecular weight — which might mask the concentration of small-molecular-weight proteins that could be relevant to my study.

I am looking for the abnormal expression, if any, of such protein molecules.
But I am concerned that if I run the serum sample directly, I will get too many bands to allow me to identify my desired molecule.

Which column should be used to separate such masking proteins from serum — or, alternatively, what previous separations should be done?

Also, what reagent concentrations should I use (particularly re: binding buffer and elution buffer)?


texts: Metabolic control theory: proof of the summation theorem?

texts:
I'm looking for a rigorous proof of the summation theorem of metabolic control theory. The only sources I find are the original papers by Kacser and Burns 1973 and Heinrich and Rapoport 1974, both of which are unclear to me.

The summation theorem is the following. Consider a linear metabolic pathway

$X_0 \xrightarrow{E_1} X_1 \xrightarrow{E_2} X_2  \cdots \xrightarrow{E_n} X_n$

Let $J$ be the steady-state flux through the pathway, and let $e_i$ be the concentrations of the enzyme $E_i$. The flux control coefficients $C_i$ is defined as the partial derivatives

$C_i = {\partial (\ln J)} / {\partial (\ln e_i)}$

The summation theorem states that for any such system, it holds that $\sum_{i=1}^n C_i = 1$. Intuitively this means that if the concentration of some enzyme has a large impact on flux, then the other must have a relatively smaller impact. It seems reasonable, but is far from obvious I think. So a proof is needed.

The proof (sketch) given by Kacser and Burns seem to rest on the assumption that $\partial (\ln J) = \sum_{i=1}^n \partial (\ln e_i)$, and given this, the proof is trivial; but this assumption is never explained further. Heinrich and Rapaport states the summation theorem in passing (p.94, "it is worth mentioning that the following relation holds"), but I don't see a proof. (But their paper is rather dense so I may have missed it.)

Anyone know of a proof of the general case?


texts: Can anyone tell me what kind of spider this is and if it might be poisonous?


texts: In the context of twin studies, what do 'unique environmental factors' and 'shared environmental factors' refer to?

texts: I was reading this study on sexual behavior and they refer to both terms without clarification. Does 'unique environmental factors' refer only to the prenatal environment or does it include individual experiences with, say, illness as well? Would friends be considered a 'shared environment factor' or an 'individual environment factor?'


texts: How to bind antibodies to study their properties?

texts:
I want to experimentally look at the behavior of antibodies. To do so, I need to be able to bind these antibodies to a substrate.
Eventually, I want to study the specificity of antibodies to know to what substrates they bind. After that, I want to study the biological activity of the antibody over time.
But my question is more basic, namely: to what material do antibodies bind non-specifically? It's not about antigens at this stage, it's just about non-specific binding of antibodies to a carrier material. Also of interest would be howw to get the antibodies of that carrier again.


texts: What is the use of having 3 antipodal cells and 2 synergids?

texts: The embryo sac which is developed from functional megaspore contains 8 nuclei.2 polar nuclei and egg fuses with sperms.3 antipodal cells and 2 synergids degenerate after fertilization.Then what is the use of having 3 antipodal cells and 2 synergids?


texts: A study found that the hepatitis C virus can live on surfaces for six weeks. Did they end the study before the seventh week began?

texts:
A study once found that the hepatitis C virus (HCV) can remain infective for six weeks on ordinary household surfaces. You can see the free full text, or a summary for busy clinicians.

What happened in the seventh week? Did the virus cease to remain viable, or did the study just end suddenly?

From part B of this figure, it looks to me like the study just ended suddenly. But I'm not a biologist, so I'd like to hear your opinion.


texts: Do axonal conduction delays have a function?

texts:
I'm reading about mathematical models of biological neural networks, which can be grouped into two categories:

The model accounts for the fact that a signal takes time to travel from the excitatory to excited neuron
The signal is modeled as if it travels instantaneously between neurons

I'm trying to understand whether a signal delay is introduced for the purpose of realistically modelling a neural network, or whether it has other functional roles in the model. So by function I mean a role in the information-processing capacity of the network that extends mere physical limitations of axon signaling. I'm referring specifically to their function in biological neural networks

Here are three distinct cases that I expect the answer should fall under, to further illustrate what I mean by function:

They don't, signal delays are a mere physical necessity of biological neural networks, irrelevant for the information-processing aspect of their operation. The differences between delay durations are primarily due to the fact that low reaction times are metabolically expensive and spatially-inefficient and are thus reserved for specialized purposes such as reflexes, instead of having a wider functional role as a parameter.
They do, signal delays are fundamentally required for neural networks to process spatio-temporal patterns. However, the differences between the durations of delays are unnecessary to explain any fundamental internal property and are still due to external factors.
They do, and the differing durations themselves are operational parameters, i.e. the function of a sub-network can only be fully understood if the ratios of the delays in signal transfers are taken into account.


texts:
I was under the impression the only signals neurons send using changes in membrane potential are action potentials. But my biology professor showed us diagrams of graded potentials and action potentials and to me they looked very similar.

What is the difference between a graded potential and an action potential?


texts: Heteroduplex and Products of cleavage of Holliday Junction (Resolution)

texts:
In homologous recombination (Holliday model), the last process i.e resolution can occur in two ways (horizontl and vertical cuts) leading to formation of either "splice" or crossover products or "patch" or non-crossovers product (as shown in the image).
The two possible products confuse me with what are crossovers. I could not understand why the "patch" product (Fig. (g) in the image) is called a non-crossover. Is it because one strand of both the homologous helices are same?
Also please do explain what is the hetero-duplex in this model?


texts: Some time ago, I read in a newspaper--though I can't recall the details--a list of (mostly artificial) sweeteners and a list comparing how many times sweeter each was than sugar. How is relative sweetness quantified? Is there a standard method?


texts: How might I break down bread into glucose in a model of the human digestive system?

texts: I need to make a model of the digestive system. It would be really nice to actually show it in action, such as by breaking down bread into glucose or something similar. Is this feasible with a small budget and non-dangerous chemicals? If so, how? This should be as similar too the real digestive system as possible.


texts:
I found a question about ants sleeping - Do ants or other insects sleep, and if so why?, but I don't think it really answers my question.

For the question, I'm mostly referring to web-making spiders, say orb webs.

So a spider set up shop inside my house late last year. It built a web high up in the corner and started catching moths and stuff. I know it's been there and it's the same spider because I've watched it grow.

But when the spider isn't catching something, eating or building a web - what is it doing? Just waiting for web vibration?

I imagine if it was outside it would be hiding or trying not to be prey. I also imagine it might be looking for a mate. What I can't figure out is what this spider does all day.

Why would it build a web where no other spiders are and then stay there for months doing nothing?


texts: These Mammals Had a Good Run, So What Happened?

texts:
One of the great mysteries of the mammals is that some of the longest-lasting just aren't with us today.  The list of these puzzling unfortunates is as follows:

Paleomerycidae

DURATION:
55.8 to 4.9 million years ago

Hyaenodonta

DURATION:
63.3 to 11.1 million years ago

Merycoidodontoidea

DURATION:  35 to 5 million years ago

Hyracodontidae

DURATION:  55.8 to 20 million years ago

Leptictidia

DURATION:  70 to 33 million years ago

Entelodontidae

DURATION:
37.2 to 16.3 million years ago

Amphiocyonidae

DURATION:
46.2 to 1.8 million years ago

Protoceratidae

DURATION:
46.2 to 4.9 million years ago

If all these numbers mean anything, it's that these groups had withstood millions of years of countless, various changes in their environments.  They had lived so long, yet despite their apparent flexibility, they tripped at the finish line.

The simple question is:  Why?


texts: How far can free radicals from UV radiation diffuse through the skin?

texts:
UV radiation damages DNA through two separate mechanisms. Direct damage occurs when a photon is absorbed by DNA. Indirect damage occurs when a photon is absorbed by a chromophore, and the excited chromophore then reacts with DNA, or reacts with other molecules, forming free radicals and causing harm via an oxydative stress mechanism.  How far can these free radicals travel?  The Wikipedia article on indirect DNA damage states

  Unlike direct DNA damage, which occurs in areas directly exposed to UV-B light, free radicals can travel through the body and affect other areas—possibly even inner organs. The traveling nature of the indirect DNA damage can be seen in the fact that the malignant melanoma can occur in places that are not directly illuminated by the sun.

This seems extremely dubious to me, but I know very little about the topic and can't find any more reputable sources discussing the question. Can indirect damage occur in adjacent non-illuminated cells?  Can it occur millimeters away from the illuminated area? Centimeters?  Can UV light harm inner organs?


texts: How do climate and location affect the Pine Processionary moth?

texts:
I have statistics on the occurence of the Pine Processionary moth (Thaumetopoea pityocampa); we have the regions that are located in Algeria, infested area in percent, the defiliation degree (small, medium and high) and we have geographical location (longitude, lattitude).

The table is as follows:

Why is there a difference between infested areas, and is there a special pattern for the distribution of this insect? Is it known what the main drivers are for determining the distribution and abundance of this moth, and thereby why some areas are more infested than others?


texts:
I'm trying to measure the colocalization of two proteins in a .tiff image taken with a wide-field fluorescence microscope. In ImageJ I have split the image into the two channels (red and green), and now I have to apply a threshold, however when I threshold both channels the bright areas corresponding to the cells are located in the darkest part of the histogram instead of the brightest part, as you can see in this image for the red channel:

https://www.screencast.com/t/QO2iVt0JM

Why ImageJ is assigning darker values to the cells rather than to the background? I'm having problems with this as I cannot properly select these cells for the colocalization analysis.
Anyone does have any clue? Any help would be greatly appreciated.


texts: In the past I dyed my hair to cover the grey, but it became a more frequent event so I decided to just go grey.  My hair has been almost entirely white for nearly 20 years.  The pigment has been returning to my hair gradually for the last 18 months.  Do you have any explanation for this?  I have tried to research this, but have not found any answers.  There is information for reasons why hair looses pigmentation, but not for its return.  Any ideas?


texts:
I'm just curious as there was a bit controversy around this topic. It is possible for person with AIDS be negative for HIV antibodies?

As of 1989, the CDC reported that 5% of all U.S. AIDS patients who had been tested for HIV to that time were HIV-negative. No figures have been reported by the CDC since 1989.

If so, how it's possible?

See:

Unexplained CD4+ T-Lymphocyte Depletion in Persons Without Evident HIV Infection -- United States at Centers for Disease Control and Prevention


texts:
I spotted this dove in a park. It was foraging among Rock Doves, Seagulls, Ibises and a few others.

It appears similar to Pied Rock Doves, but I am not certain if this is correct.

Any idea what the name of this dove is?


texts: Why do living things go belly up as they die?

texts:
I have seen birds, lizards, frogs, fish, etc in various places on their back dead. May be insecticides cause them to flip over but I do not believe every upside down creature died by poison as stated in this question's answer: Why do cockroaches flip over when they die? and the roach question only covers roaches and insecticides. My question covers all animals not affected by poison that are belly up.

Other than poisoning is there any other reasons like DNA programming on behavior or muscle spasms that cause this?


texts: Could cyanobacteria thrive with very high CO2 concentrations and almost no oxygen to start with?

texts:
Has there been research to see if cyanobacteria could live in high levels of CO2, like in the atmosphere of Venus ?

Because cyanobacteria caused the Great Oxygenation Event one might expect that they could !


texts: Are Measles patients infectious until death?

texts:
I'm examining a dataset of a measles outbreak, and for each patient I have the date of first appearance of symptoms $t_1$, date of appearance of rash $t_2$, and if applicable, date of death $t_d$. According to the literature, patients are infectious for one day before appearance of symptoms, and up to about 4 days from appearance of rash, so the interval of infectiousness is approximately $\left[t_1 -1, t_2 + 4\right]$. After this, most of the time their symptoms gradually abate and they get better.

However, if a patient dies, presumably they remained sick until they died. If $t_d$ is like, 10 or 15 days after $t_2$, are they infectious during all of this period? Or is it reasonable to conclude that they're infectious for the same length of time as everyone else, and the symptoms that kill them are non-infectious complications?


texts: Do humans have any biological adaptations to eating cooked food?

texts: Humans have been cooking food for at least tens of thousands of years. The presumed reason why cooking took root in nearly all human cultures is that cooked food is easier to digest. However, cooking food can also generate toxic compounds such as polycyclic aromatic hydrocarbons, which would not be found in the uncooked version of the food. Considering that humans have been eating cooked food for such a long time, I am wondering whether humans evolved any adaptations to eating cooked food, e.g., that certain types of foods, when cooked, are more toxic to our closest relatives (great apes) than they are to humans, because we have more ability to metabolize the toxic compounds.


texts: Recombination frequency as a function of genomic location in E coli?

texts: Are there any databases or papers that give recombination frequency as a function of position in the E coli genome?


texts: What implications has the missing 2'-OH on the capability of DNA to form 3D structures?

texts:
The chemical difference between RNA and DNA is the missing 2'-hydroxyl group in the nucleotides that build DNA. The major effect of that change that I know of is the higher stability of DNA compared to RNA. But I'm wondering whether this difference has significant implications for the ability of DNA to form compex, three-dimensional structures.

RNA is known to be able to from complex tertiary structures and function as ribozymes. It clearly has the ability to form a wide range of structures and can catalyze a variety of chemical reactions.

As far as I know, there are no naturally occuring catalytic DNAs known. But a number of synthetic DNA enzymes have been created in the lab, so it is generally possible for DNA to form catalytic structures (see Breaker and Joyce 1994 for the first created DNA enzyme).

I'm wondering whether the missing 2'-OH means that DNA has less potential to form complex structures compared to RNA? I imagine it changes the ability to create hydrogen bonds, but I don't know if it would significantly decrease the potential structures that DNA could adopt.

Breaker RR, Joyce GF; (December 1994). "A DNA enzyme that cleaves RNA". Chem Biol. 1 (4): 223–9


texts: My textbook says that the yellow appearance of a jaundiced person is due to the accumulation of bile pigments in the skin. I am unable to understand why these pigments are not deposited in a healthy person? Please help.


texts: Is AT or GC content important in electrophoresis?

texts: Will it make a difference in running speed if we run samples of same no of bases but different AT - GC content ?


texts: Does endo- and (or) exocytosis require energy? Do they belong to active / passive transport?

texts:
I expect vesicle formation and fusion to require energy input; however, I'm not sure about which of endocytosis and exocytosis require energy and how they use the energy input.

Do they belong to active or passive transport?


texts: How can two biological sequences be anything but homologous?

texts:
If we consider homology between two nucleotide sequences as a yes/no answer to whether they have shared a common ancestral sequence, then given that all life share common ancestry and sequences are carried by living things, then how can two biological sequences be anything but homologous?

One possibility I can think of is perhaps natural transformation in bacterial---but even so, the DNA sequences picked up must have come from a biological source.

(I assume that it must be possible that there are sequences that are non-homologous, because otherwise there wouldn't be a need to point out which things are homologous, i.e. I assume that the concept of sequence homology would not be as widely used as it is right now)

There has been some discussion on my claim that homology should take a Boolean value. As I have stated in the comments, for this I refer to Inkpen, S.A. & Doolittle, W.F. J's "Molecular Phylogenetics and the Perennial Problem of Homology" in Mol Evol (2016), pp. 187.

  Nevertheless, there is a general understanding that conflating the extent of similarity and the inference of common descent is always a misuse of the concept—that there can be no such thing as ‘‘percent homology.’


texts:
While I am familiar with some of the conditions for the Nernst Equation, for example:

1) "The membrane is only permeable to one ion even if there are several other ions in the system"

there is an assumption/condition that I have yet to see mentioned (and I am pretty sure that it is an essential one that must be included). That assumption is as follows:

The two solutions separated by the selectively permeable membrane must initially have the same total charge...i.e. there is no initial potential difference between the 2 sides of the membrane

I believe this must be true because of the following 3 cases:

for all 3 cases, only potassium is permeable, and there is a "Left Side" and a "Right Side" on either side of the selectively permeable membrane.

A) Left Side: 25 mM K+, 125 mM Na+ |&| Right Side: 125 mM K+, 25 mM Na+

B) Left Side: 25 mM K+, 10000000000 mM Na+ |&| Right Side: 125 mM K+, 25 mM Na+

C) Left Side: 25 mM K+, 0.00000000001 mM Na+ |&| Right Side: 125 mM K+, 25 mM Na+

Without using my proposed assumption, in all 3 cases, the Nernst equation for potassium would be the same:

(RT)/(ZF) * ln (25/125)

However, I fail to see how case B & C could have the same Nernst potential for potassium as case A when the electrical forces on the left side of the membrane are completely different! Let's use case B as an example. Clearly, the potassium concentration differences exist between the two sides (25 mM vs 125 mM), BUT there is an enormous electrical repulsive force imposed by the sodium (1000000000 mM Na+) so there is no way that the same amount of potassium will pass over to the left side as it would in Case A, right?

Could someone please clarify?


texts: Did snow leopards loose the ability to roar or never have it?

texts: Since snow leopards are the only species in the genus Panthera that can't roar, was this something the others developed after snow leopards diverged or something that snow leopards lost?


texts: This gorgeous and sweet grape I collected in central Italy. I would like to know the name of this variety to get more information about it. I tried to compare with some pictures in Google but I am no grape/wine expert so it's really hard to figure it out for me.


texts: How many photons are used to make one glucose?

texts:
This was a question in a test. The options were

(1) 8

(2) 16

(3) 24

(4) 48

My answer is 30 which was not in options.  Given answer was 48.

12 NADPH
18 ATP for one glucose

12 NADPH and ATP from z scheme where 24 photons are used.

6 ATP more from cyclic where 6 photons are used.

Net 30.

Can someone point out an argument against this?

One explanation for 48 is:

2 electron each hydrogen atom

4 electrons per water molecule

2 water molecules for one oxygen molecule

8 electrons=8 photons for each oxygen,

each glucose 6 oxygen so 8×6 = 48

But what is the mistake in argument for 30?


texts: I am a physicist but I have always wanted to understand how my digestion takes place in as much detail as possible. I have no idea about books or reference on the subject of Gastro-intestinal and digestive physiology. Can you help me?


texts: Differences on biological classification?

texts: Why we use the term phylum for kingdom animali but for kingdom planti ,fungi and prokaryota we use them division?                         What difference between phylum and division ?


texts: Why do Type II Restriction Endonucleases cleave at palindromic sequences?

texts: Type II Restriction enzymes usually cut only at palindromic sequences. Is there any specific reason for that? Is there any advantage for bacteria if they cleave phage DNA at this type of sequence?


texts: What species is the smallest living bird in the world? What circumstances limit the bird size from the bottom?


texts: How were the first genes isolated from genomic or cDNA libraries without already knowing a hybridization probe?

texts:
Let us go back in time to around 1975. It is my understanding that at that point (or at least by the end of the decade), both genomic and cDNA libraries had been created for a few organisms, e.g. rabbits. I'm interested in the logic of techniques that first used these libraries to isolate genes encoding for particular proteins. Note: I'm not interested in how we'd isolate a gene today; I want to understand the history.

First, consider the following thought experiment. Say it's around 1975. The one assignment for my Cal Tech biology class is a doozy: it goes as follows. The instructor (Tom Maniastis?) hands me a protein along with the cells from which the protein was isolated as well as genomic and cDNA libraries of the organism that makes the protein; the challenge is to isolate the gene encoding for the protein. I do not know anything about the protein except that the product I've been given is pure.

Of course, the basic idea is simple: isolate the gene by screening the libraries with a radioactive nucleic acid probe and using a hybridization assay. But alas, I do not have a complementary probe: all I have is the protein! What do I do?

Here is one solution I can imagine. (I don't know whether it was possible around 1975, much less whether it actually happened.) I could try to isolate the mRNA that codes for my protein (but how to do that?), then radiolabel it and use the radiolabelled mRNA as a probe in a hybridization assay on the cDNA library (not the genomic library, since the unprocessed DNA could have noncoding regions).

Would this have worked?
Did anyone actually do this?
If yes to either (1) or (2), how could one figure out which mRNA coded for the protein?

The question, in essence, is how to get to DNA, given only a protein, circa 1975.


texts: Is spliceosomal RNA called snRNP or snRNA?

texts:
I have been reading articles by various sources, and they seem to interchangeably call the U1/U2/U4/U6 compounds involved in RNA splicing snRNPs as well as snRNAs.

This confuses me deeply. They must only be one or the other, no?
Thank you in advance!


texts: Why spermatogenesis is an independent process while formation of ovum is dependent on fertilization by sperm?

texts:
At the time of ovulation,secondary oocyte is arrested at Metaphase II and goes into the fallopian tube.If fertilization occurs, sperm binds with secondary oocyte and releases Anaphase promoting factor which leads to completion of meiosis II,ovum is formed and it subsequently gets converted into zygote.
My question is that why formation of ovum is dependent on fertilization by sperm and why formation of sperms is independent process? Has it some benefits for nature?


texts: How to check if a fastq file has single or paired end reads

texts:
I am trying to check if a fastq file has single or paired end reads. How can I achieve this with an error-proof method?

I checked wikipedia and MAQ but I want to know if is there a reliable document that describes all possible variants in sequence ID to check for single/paired end reads.

I am searching also for a library, better in Python, to achieve this.

Thanks


texts:
I made a statement about tropical rainforests, and I want to know if it's somewhat true or not:

The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The reason that a tropical rainforest has a huge amount of vegetation is because of the quick mineralisation. If a dead leaf falls onto the ground, it immediately gets turned into minerals, which the plants immediately use for sustaining theirselves


texts: Are (baseline) high blood levels of melatonin associated with either circadian rhythm or mood disorders?

texts:
(Exogenous) melatonin is administered at night for treatment of circadian rhythm disorders, but melatonin taken during the day is linked with depression.

I would like to know if high blood levels of (endogenous) melatonin (at a steady state, throughout the day) might be linked with mood or sleep disorders (or have any effect at all), or if the body's response to melatonin adjusts accordingly.

I think the answer to this SE question is related, but I can't find the source using a reverse image search.


texts: Example of impossibility in the nested hierarchy?

texts:
I have conversations with evolution deniers, and I've read that the best single piece of evidence for evolution is the congruence of the genetic and morphological nested hierarchies, and the fact that they are predicted on evolution, but not on intelligent design.

I think I have an example of what would falsify the nested hierarchy; please check me on this, I want to get this right.

Because evolution is a historical process, an organism can only share characteristics, or have varied characteristics, of one of its ancestors.  If an organism had characteristics that came laterally (?) across the nested hierarchy, as opposed to up or down through its ancestry, that would falsify the hierarchy.  An example of this would be a primate with two post-orbital fenestrae (see pic)..

And, we don't find such organisms.

This is not predicted on design because if you design from scratch, without the necessity of varying ancestors' characteristics, you are not limited by not designing a primate with two post-orbital fenestrae.

Do I have this right?


texts: can a bacterial protease inhibitor cocktail be used for Western Blotting involving HUVEC cells and HT-29 adenocarcinoma cells?

texts:
Dear fellow biochemists,

I need some advice on Western Blotting, more specifically the use of certain protease inhibitors with the RIPA cell lysis buffer and protease inhibitor cocktail. A Millipore technical representative recommended my using "539134 | Protease Inhibitor Cocktail Set III, EDTA-Free - Calbiochem" as a good general protease inhibitor cocktail.

I have another protease inhibitor cocktail which includes: AEBSF, bestatin, E-64, and pepstatin A (E.coli protease inhibitor cocktail) but it does not include the aprotinin or the leupeptin inhibitors. Is there a risk of proteolysis in a mammalian cell lysate without these latter 2 inhibitors? The specific cell types which we are using are: HUVEC (human umbilical vein endothelial cells) and HT-29 adenocarcinoma cell line.


texts:
The short version of my question is this:

  It's some time in the future. I go into my back garden and focus my telescope on the Moon. The surface is virtually covered with giant greenhouses, growing food to support the cities that have sprung up there. The question is: what plants are they growing in those greenhouses?

Factors such as temperature, water, soil quality etc. can be controlled easily enough if you already have the ability to build sealed greenhouses in a vacuum. There are also a number of experiments on growing food in closed systems where air and water are recycled (the Biosphere 2 project being the best known). The low gravity can't be controlled, but there have been a number of experiments on plant growth in microgravity conducted on the international space station, so growing plants in Lunar gravity should be possible. There have also been some interesting results from growing plants in an Earth-based approximation to Lunar soil.

However, another important issue is the length of the Lunar day, which is 28 Earth days long, meaning that the Sun shines continuously for two Earth weeks, followed by two weeks of total darkness. I'm interested in what's known about how plants could adapt to this, but I haven't been able to find any research papers on the subject. Of course it would be possible to simulate an Earth day using artificial lighting, but the energy costs of doing this on a large scale would be rather high, so for economic reasons future Lunar farmers would likely want to keep it to a minimum.

So my first question is, has any research been done on the effect of extreme changes in day length on plant growth?

Secondly, is there any type of food plant that would be particularly likely to cope with such an environment (perhaps with some suitable genetic modifications)? For example, would normal crop plants such as cereals be able to build up enough sugar reserves in two weeks to survive the next two weeks in total darkness? If not, is there another type of plant that's more likely to be able to adapt to this? Or as an alternative strategy, is there any crop that grows fast enough that its shoots could be harvested after only two weeks of continuous sunlight? (Some individuals would have to be grown to maturity under artificial light in order to produce seeds, of course.)

Finally, I'd be grateful for pointers towards research on any other issues that I might have missed that are relevant to the problem of large-scale Lunar agriculture.


texts: Fixing plant leaf tissue for tensile tests

texts:
I'm a new master's student in mechanical engineering, and I'm researching crop biomechanics. We need to do some tensile tests on samples of corn stalk sheath, which involves securely and evenly gripping a sample at two ends in a machine and pulling slowly until the sample experiences mechanical failure.

My advisor thought we might simply be able to use an adhesive such as super glue to fix the sheath samples to the tensile test machine, but he found that super glue doesn't adhere well to the sheath because of a waxy layer on the surface.

As someone who doesn't have a botany or biology background, I'm wondering if there are adhesives out there already that would serve such a purpose? Or perhaps another way of fixing the sheath to the machine? Normally tensile machines are used to grip metal or polymer samples, and have simple claw-like grips at either end.


texts:
Ok, this is a bit of a tangent question, but it came up yesterday and I didn't know the answer:
How are arms and legs defined physiologically? For example, we say humans have two arms and two legs, while cats have four legs, and some monkeys (appear) to have four arms (although I guess they could be legs too). It's really unclear to me how we make these distinctions.

So:

What is the physiological definition of both "arm" and "leg"? How are they different?


texts: Transfer of antibodies in breast milk of humans

texts:
Why isn't the IgA secreted in breast milk digested due to proteases of the digestive system in the baby?

Wikipedia says:

  The secretory component of sIgA protects the immunoglobulin from being
  degraded by proteolytic enzymes, thus sIgA can survive in the harsh
  gastrointestinal tract environment and provide protection against
  microbes that multiply in body secretions.

But what exactly does the secretory component do?  What is the secretory component?  Is IgA absorbed in the circulation of fetus? I remember reading it somewhere that it is not absorbed, at least in humans. Please answer these questions focusing more on humans. Though, information about other animals will be appreciated as well.


texts: Do Gametes contain mitochondria/chloroplasts from their parent cell?

texts:
It has now been established (according to the Cambridge A level text book) that

  organisms form a symbiotic
  partnership, typically by one engulfing the other
  – a process known as endosymbiosis. Dramatic
  evolutionary changes result.
  The classic examples, now confirmed by later
  work, were the suggestions that mitochondria and
  chloroplasts were originally free-living bacteria
  (prokaryotes) which invaded the ancestors of modern
  eukaryotic cells (cells with nuclei).

It also states that

  It was also discovered in the 1960s that mitochondria
  and chloroplasts contain small, circular DNA molecules,
  also like those found in bacteria

and lastly

  The DNA and ribosomes of
  mitochondria and chloroplasts are still active and
  responsible for the coding and synthesis of certain vital
  proteins, but mitochondria and chloroplasts can no longer
  live independently.

So my question is:

Is this DNA found in the mitochondria and chloroplasts coded for in the host's (animal's or plant's) DNA.

If not are there fully formed mitochondria and/or chloroplasts in all gametes (obviously chloroplasts only in the plant gametes) which were transferred directly from the parent who had them transferred directly from their parent and so on?

If so are all the mitochondria and chloroplasts of one type identical in a organism? Are they almost identicle in families (of organisms not the classifictaion Family)?


texts:
I think it can because there are many parts in lungs.
Like for some COPD patients.
However, I am not sure if COPD patients can have infarction.

Lungs have parallel circulation.
Red infarct is possible there.
Blood can flow there.
One symptom should be at least pain.
So now, I think no asymptomatic possible.
But still, I am not sure.

Can pulmonary infarction be asymptomatic?


texts: How do detergents get in hydrophobic membrane interior?

texts:
According to Molecular And Cellular Biology (Stephen L. Wolfe),

  Membranes disperse almost instantaneously if exposed to a nonpolar environment or to detergents, which are amphipathic molecules that can form a hydrophilic coat around the hydrophobic portions of membrane lipids and proteins in water solutions.

This might be a stupid question but... if detergents can 'form coats around hydrophobic portions' of membrane-suspended molecules, they must, somehow get in the hydrophobic membrane interior... right?

How do they get in the membrane interior? Do they form clusters like endocytic vesicles? What happens after they form hydrophilic coats around hydrophobic molecule regions?


texts: dNTP concentration for reverse transcription from RNA to cDNA

texts:
Does it affect the results if I use the half of dNTP amount in a reaction that it says in my protocol?
I usually use 4 microlitres per reaction and this time I did a mistake and I used 2.

The final cDNA will be used for qPCR relative cuantification,so I am not sure if that will affect my results.


texts: Furry Bug that swarms only certain plant

texts:
What is this strange bug?

It swarms only on one certain plant with trumpet-shaped red flowers (in the picture the flowers are all shriveled and the leaves are in the foreground) and totally coats it until the bush dries up. It spreads very rapidly but only to this particular plant - will not touch any other. The bugs don't noticeably move, giving the impression that the whole bush has developed white fur.

Picture taken in Israel:

EDIT:

Here's a closeup of a single specimen (taken from one of the leaves in the foreground):

And it seems the plant is a hibiscus:
http://homeguides.sfgate.com/hibiscus-leaf-87355.html


texts: How many hairs per sq. cm. (or inch) do hamsters have on average?

texts:
How many hairs per square centimeter (or inch) do common pet hamsters (Mesocricetus auratus or Phodopus sungorus) have on average?
I thought this would be easy to find by googling, but the best I've been able to find is this 1986 article, which isn't very clear in answering the question.


texts: Why is there more variation in proteins than genes?

texts:
The Genome of a cell or organism is the same as that of the entire organism. However, the proteome of an organism is much greater than that of each cell (unless the organism is unicellular).
How do you account for the presence of more variation among of proteins than there are in genes?

The simple answer would be "there are more proteins than genes", but I'm more interested in why. Is it sufficient to say that during gene expression a single gene codes for multiple proteins (Alternative Splicing) and ribosomes translating mRNA to polypeptide chains (Posttranslational modification)? Could someone expand more on this?


texts:
Flip-flopping of lipids (and in proteins it is impossible) in plasma membrane is rare due to high energy barrier (video ref). However, it is an important mechanism since it allows asymmetric distribution of lipids in cell membrane.
Question: If a specific lipid is flipped E.g. phosphatidylinositol from cytoplasm side to extra-cellular side (E.g. by flippase), what mechanism can the cell do to ensure it will stay towards the extra-cellular fluid side but not flip-flop AGAIN (i.e. establish the asymmetry & enable its function)?


texts:
I am reading this and this where I am considering this sentence

  [N]o baseline parasympathetic innervation [in transplanted heart].

Does this sentence imply that the heart work then in full sympaticus all the time?
Probably, through altered systems, but still.
At least the regulation of blood pressure strongly supports this, here for the generic medication plan.

Does transplanted heart have full sympaticus without medication?

Notification of terminology. I tend to use overloading in writing.
For instance, I can say that there is sympathetic and parasympathetic supply to the heart i.e. innervations of S and PS through endocrine system to the heart.

I am not yet completely sure how the recipient's body can target the alpha and beta receptors of donors in heart. Are there any variations of these receptors? If yes, then the effect of sympathetic stimulation would also differ from the original stimulation.
So full sympaticus (or original) may not be present.
The new stimulation may lead to greater or smaller activation of sympaticus.


texts: RNA or ribosome, which one moves during translation?

texts: During translation ribosomes decode the genetic information present in the mRNA and protein synthesis takes place.  During this process which of those two does move, the ribosome or the mRNA?


texts: This turtle was displaced by hurricane Harvey in Houston, Texas, USA (Buffalo  Bayou and Dunlavy). It appears to be a snapper. Can someone identify the exact species?


texts: How large a part of the corona-virus is coding?

texts: If you find an example of a sequenced string of coronavirus it is about 30.000 long. Looking for example here https://nextstrain.org/ncov/europe you'll see that by far the largest part of this is actually coding. But is that because that is the entire strain or is it because they are only showing the ORF-part? If the latter is the case how large is the non-coding part then compared to the coding part?


texts: What does differential consumption mean?

texts:
I have not been able to find any definition of differential consumption online. What does it mean in this quotation?

  Vertebrates can influence natural fire regimes in several ways. First, herbivores limit fuel quantity by consuming and recy- cling plant matter that would otherwise accumulate as litter, and by reducing the density of vegetation [3]. Second, differential consumption of plant growth forms can enforce changes in the composition of vegetation and thereby alter the type and arrangement of fuel. Third, herbivory can gen- erate large-scale habitat heterogeneity, as a result of variation in herbivore activity in response to factors such as terrain and water availability [3,11], and this can mean that zones of low and high flammability are interspersed in arrangements that could impede the spread of landscape fires. Finally, herbivores and other animals may alter the abiotic environment in ways that affect flammability: by forming trails, dust-baths or leks, large animals create lines or patches of bare ground that can act as fire breaks, while some species forage by turning over or digging through the litter layer and surface soils, and in the process bury fine fuels and thus reduce fuel loads. In the sections below, we explore the evidence supporting these effects of herbivores on fuel and fire regimes, in the past and present.

Johnson, Christopher N., et al. “Can Trophic Rewilding Reduce the Impact of Fire in a More Flammable World?” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 373, no. 1761, Dec. 2018, doi:10.1098/rstb.2017.0443


texts: Values of Miu_max and Ks from parameter estimation?

texts:
Background

I have this simple biomass growth model:
$$
\mu = \mu_{max}\cdot \left(\frac{S}{K_S+S}\right) \cdot \left(\frac{1}{1+S/K_{iS}}\right) \cdot \left(\frac{K_{iP}}{K_{iP}+P}\right) \\
\frac{dX}{dt} = \mu \cdot X \\
\frac{dS}{dt} = -1 \cdot ( \frac{\mu}{Y_{XS}} \cdot X + mS \cdot X) \\
\frac{dP}{dt} = a \cdot \frac{dX}{dt} + b \cdot X$$

Problem

I can fit the model on experimental data (see the Figure), but the values of $\mu_{max}$ or $K_S$ are often quite unrealistic. In this plot the $\mu_{max}$ is 3.9 and $K_S$ is 10.

Question

Since $\mu_{max}$ and $K_S$ are bounded in Monod-based $\mu$ expressions, is it possible to get real values of both of these particular parameters through parameter estimation techniques? Or one of these parameters should be obtained by other methods?


texts:
Does a full tear of the gluteus minimus tendon result in a long-lasting inflammatory response?

This answer mentions:

  An isolated gluteus minimus tear still causes functional problems because of the associated inflammatory response

But I read on {1}:

  “signs of either acute or chronic inflammation have not been found in any surgical pathologic specimens in patients with clinically diagnosed lateral tennis elbow syndrome,”

Note that tendon tears are present in a tennis elbow (a.k.a. lateral epicondylopathy). From {2}:

  Review of MRI findings from 24 patients with epicondylitis reported increased intratendon signal on both T1 and T2 pulse sequences58 with occasional bone marrow edema pattern in the epicondyle. Other studies have shown thickening, edema, and tears of the common extensor tendon.

References:

{1} Bass, Evelyn. "Tendinopathy: why the difference between tendinitis and tendinosis matters." International journal of therapeutic massage & bodywork 5, no. 1 (2012): 14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3312643/
{2} Taylor, Samuel A., and Jo A. Hannafin. "Evaluation and management of elbow tendinopathy." Sports Health 4, no. 5 (2012): 384-393.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3435941/


texts: Biological significance of correlation between the radius of gyration and number of layers of convex hull of protein structure

texts:
While going through the paper titled "GEOMETRIC ANALYSIS OF THE CONFORMATIONAL FEATURES OF PROTEIN STRUCTURES" by Manish Dutt, I came to know that there is a correlation between the radius of gyration and the number of layers of convex hull of each proteins 3D structure (convex hull layers are formed by forming the convex hull of a set of points, which forms the first layer, then removing them, and recalculating another set of boundary points, i.i., second convex hull, which form the second layer).
Now my questions is, what is the biological significance of this correlation? Or is there any?


texts: How do you check how many cones you have in your eye?

texts:
Following my previous question: What color does the other cone in Tetrachromacy correspond to?

People with normal color vision posses 3 cones in their eye. But there are some rare cases when people can have 4 cones (Tetrachromacy). These people, some of them will notice the shades difference in the scene through their eye. And the rest won't notice it, because simply their 4th cone is activated in the close peak value with the the L-cone. Therefore eye will not find any difference and will encode only one color even if it's coming from 2 cones stimuli.

How do you check, to know how many cones you have in your eye ? If the case is, even people who posses 4 cones can't even notice the shades difference ?


texts:
I am new to Biology and I am reading some papers about kinase proteins. I know what kinases do in the body. However, I found it hard to understand what are "kinetics". I googled this term but it seems it is a general term and I couldn't understand it.
I came across the following sentence in a paper, and I am not able to understand it:
"many substrates of a given kinase have similar temporal kinetics"
I know what "substrates" and "kinase" means. But I don't know what "temporal kinetics" means here.
I appreciate the chance if somebody let me know the meaning of "temporal kinetics".
Thanks


texts: Would it be possible to eat things from another planet

texts:
Although at first glance my question is perhaps better suited for a space exploration or sci-fi forum I looked  and felt this forum was more appropriate.

What makes plants and animals edible and allows us to gain nutrition from them? If life evolved separately from life on earth would any of it be edible to us or to any other creature that evolved on this planet.

My question is not about stuff being toxic, its about if anything other than life on earth, would be digestible? Do we need to evolve side by side with our food? I know of convergent evolution, that may make things look similar, but is there something at a cellular level that makes things edible. Does everything edible have DNA?

I don't have an academic background in biology so apologies if this question sounds silly. It's been bugging me for ages. My gut feeling tells me that nothing will be edible but I don't have any science to back that up.

I'm a vegetarian so I'm not just thinking about hunting and eating aliens either!

Thanks.


texts: I am currently preparing a PCR mastermix for the first time, and have a few questions regarding the distribution. I am trying to amplify a specific gene cluster in a sample of DNA so I can use it in a cloning vector; however, I am not sure how many separate PCR reaction mixtures I should prepare in my mastermix for this purpose? Also, what is the purpose of a negative PCR reaction mixture (withouth the template DNA), as I saw a procedure recomend making one. Should I prepare the same number of negative reactions as positive, or should I prepare only 1?


texts: Using BLAST for molecular replacement in structural biology

texts: This is my first time trying to do molecular replacement to solve a protein structure. I am using the NCBI blastp program to find suitable search models. When choosing a search model, I understand that sequence identity is the most important -- but should I also take into account e-values or query coverage (i.e, what % of my query sequence is in the alignment) or any other factors for the purpose of molecular replacement? Thank you for your help!


texts: Peach pits with two seeds: Are the seeds identical twins?

texts:
I have Prunus persica peach pits that have two seeds.

My question is simple:

Do the seeds have the same DNA? (are they identical twins?)


texts: is it true to say that "fibrous skeleton is between all of the myocardium and most of the cardiac muscle attach to that"? cause I can't get this that how can it be between all the muscles.


texts: Is casein hydrolysate the same thing as casamino acids?

texts: Probably a dumb question, but these seem identical. If a protocol calls for one, can I use the other instead?


texts: Trying to understand reduction of color dimension in colorblind case

texts:
I understand that dichromats have one of their cone missing/not functioning. And as for Monochromats, 2 or all of their 3 cones are missing/not functioning. And I read from Wikipedia - Color Blindness :

  Dichromacy occurs when one of the cone pigments is missing and color is reduced to two dimensions.

and

  Monochromacy occurs when two or all three of the cone pigments are missing and color and lightness vision is reduced to one dimension.

Since in the description they relate the cones with Red, Blue, Green (RGB) a lot, eventhough I'm fully aware that relation of cones and RGB is most likely for historical reason . I'd like to assume in this reduction from 3-dimensional into less dimensional colorspace dimension written in Wikipedia based on RGB colorspace.

This is original RGB colorspace in 3-Dimension

Question 1 : How exactly reduction from 3-dimensional to 2-dimensional or even 1-dimensional in colorblind case happen ? For example in Protanopia, would they lose the Red axis ? So only Blue and Green axis left ? (Any reference will be appreciated).

I also read this question If people with colorblindness lack one type of cone cells, shouldn't they be unable to recognize one particular color?. And it's written that Dichromats can match any color they see with some mixture of just two primary colors. Cones do not literally interpret colors. The three cones work together to encode a signal.

Question 2 : If cones don't really interpret any color in human color vision system. Is it wise that losing cone means reduce from 3-dimensional color into 2-dimensional by completely erase the corresponding color axis to the cone ?

[UPDATE]

For Question 1 :

Taken from the book Visual Transduction and Non-Visual Light Perception (p308),

Univariance, Monochromacy, Dichromacy, and Trichromacy

  If only one photoreceptor type operates, vision is monochromatic or reduced to a single dimension

  If only two cone photoreceptors operate, vision is dichromatic or reduced to two dimensions

and

  Most observers
  with normal color vision have three classes of cone photoreceptor and are therefore trichromatic.

So, I'm sure in my Question 1, they really refer to Young–Helmholtz Trichromatic theory. A theory when human color vision possess 3 types of cones thus they have three dimensions of color vision.

However, I still need some opinion related to Question 2. Any comments will be appreciated.


texts: What is the effect of pesticides on worm growth?

texts:
As a new semester begins, we were asked to propose ideas for investigatory projects. Our idea revolves around the effects of pesticides on non-target organisms. Since frequent use of pesticides may potentially affect the health of the soil, we chose the earthworms as our target organism. Our experimental set-up was revolves around studying their growth. Two containers (Container A-Control, Container B-Experimental) would be filled with soil and other things that are essential for worms to live. In container A, normal soil would be used. On container B, we would spray pesticide on the soil and mix them so that it really gets in the soil. After that, we would place the worms (5 each container). The allotted time for data gathering and analysis is 3 weeks. Given this situation, we would observe the behavior of the worm each day for 10 to 14 days (depending on our schedule) and their growth on the last day by measuring their length, weight, and describing their color.

I think that our set-up is logical instead of finding farms that sprayed pesticide for the last 20 or so years which is difficult in our situation. Does anyone have any feedback on the particulars of the experiment based on previous research on the subject?


texts: Is Richard Dawkins's interpretation of the theory of evolution circularly?

texts:
I think we are all familiar with the basics of Dawkins's theory of evolution. In a nutshell: All creatures are nothing but vehicles of genes with the sole purpose of passing through these genes, and in the case of human beings besides genes also memes are involved.

Isn't this interpretation of evolution circularly:
"Why do all organisms exist? Because the purpose of organisms is to pass on genes which have the ability to develop new organisms, thereby creating new organisms under all kinds of environmental pressures". In short: "Life exists to produce new life", which is a circular expression because, in the reason we search for life, the term "life" (for which we try to find a reason) is used.

I think there are more "friendly" interpretations of evolution, of which I have no doubt that it took place.You can interpret evolution for example from a less egoistic perspective, and say evolution takes place to give new organisms a chance to live. Ande, in the case of human beings, create memes to let other people enjoy them (and not just to let your memes live further in other human beings).

If we follow Dawkins's interpretation then the scientific meme is self-undermining because the way we use science is damaging the earth to such an extent that it's the question if the earth will face a long-term future.


texts: Looking for protocol to produce a drosophila primary cell line

texts: I'm looking for a general (and easy, this is going to be for an undergrad class) protocol to isolate and culture primary cells from fruit flies.


texts: Why is Portuguese man o' war considered a colony?

texts:
The wikipedia entry on the Portuguese man o' war says:

  ... the Portuguese man o' war is ... not actually a single multicellular organism but a colonial organism made up of many highly specialized minute individuals called zooids. These zooids are attached to one another and physiologically integrated to the extent that they are incapable of independent survival. (emphasis added)

This is contradictory. If it's got multiple cells, and those cells are highly specialized to the point of being incapable of surviving on their own, then how does that differ from a multicellular organism? That last sentence seems like it describes the cells in my body.

In fact, the entry colonial organisms says:

  The difference between a multicellular organism and a colonial organism is that individual organisms from a colony can, if separated, survive on their own, while cells from a multicellular life form (e.g., cells from a brain) cannot. (emphasis added)

So, is the Portuguese man o' war a colony or a multicellular organism? And if it's a colony, can its zooids survive independently, the wikipedia text notwithstanding?


texts: Can enzymes be modeled using classical mechanics?

texts:
When enzymes interact with substrates (i.e. a small ADP molecule and the much larger ATP synthase), does quantum mechanics play a significant role? Or can the interactions be relatively accurately be understood using simply classical mechanics principles?

For example, considering a free body diagram when I insert a key into a lock, the interactions between the key and the lock can be accurately modeled using simply classical mechanics (such as friction, normal forces, etc).

However, since the scale of proteins and molecules are much smaller, could the binding of ADP to ATP synthase still be accurately modeled using classical mechanics (i.e. electrostatic forces, physical contact forces, etc.)? Or are quantum principles very significant?


texts: Is there a way tell apart dinosaurs from similar extinct reptiles?

texts: When I was a child, I thought I knew what a dinosaur was. But, as I grew older, I was told that many of the extinct species that I thought were dinosaurs (dimetrodons, pterosaurs, plesiosaurs, etc.) were not in fact dinosaurs. Is there a reasonably quick way for a lay person to tell apart true dinosaurs from non-dinosaurs without taking up an in-depth, species-by-species study of paleontology?


texts: what is the difference between osciloscope and electrocardiograph?

texts: I am completely confused about these two devices! as far as I know, oscilloscope and electrocardiograph, both, show the heat waves(P, QRS, T) so what is the difference between their job?


texts: conservation of C-peptide sequence in the guinea pig

texts:
Where can I compare the C-peptide sequence of guinea pig with human or mouse?
I am also interested in finding whether the guinea pig has insulin 1 and 2 to know whether I could use an anti-C-peptide 1 and 2?


texts:
Consider $m$ loci with heterozygote advantage (overdominance) such that the fitness of the two homozygotes is $1-\frac{s}{2}$ and the fitness of the heterozygotes is $1+\frac{s}{2}$, where $s>0$. We'll assume that the fitness of an individual is given by the multiplication of the fitness component on each locus. In consequence, the fitness of the best possible genotype is given by $\left(1+\frac{s}{2}\right)^m$.

According to this book, an individual is heterozygote at $j$ of these $m$ loci with probability

$${m\choose j}\left(\frac{1}{2}\right)^m$$

and the equilibrium population mean fitness $\hat w$ is

$$\hat w = \sum_{j=0}^m {m\choose j}\left(\frac{1}{2}\right)^m  \left(1+\frac{s}{2}\right)^j  \left(1-\frac{s}{2}\right)^{m-j} = 1$$

I don't understand any of these two equations! Can you help me to understand how they have been calculated?

For the moment I just enjoyed proving that $\hat w = 1$. We can reformulate $\hat w$ as

$$\hat w = \left(\frac{1}{2}\right)^m  \sum_{j=0}^m {m\choose j} \left(1+\frac{s}{2}\right)^j  \left(1-\frac{s}{2}\right)^{m-j} = 1$$

,then using the binomial identity

$$ \hat w = \left(\frac{1}{2}\right)^m \left(\left(1+\frac{s}{2}\right) + \left(1-\frac{s}{2}\right)\right)^{\space m}$$
$$\hat w = \left(\frac{1}{2}\right)^m 2^m$$
$$ \hat w = 1 $$


texts: What animal is this? A bee? red mason bee? (Bee-like with brown/orange fur)

texts:
The picture was taken at the Bodensee (Lake Constance) in Southwestern Germany in June 2019. I tried to Google "Bee with brown fur", but the only thing that came up was a red mason bee, and the resulting pictures didn't look quite like this photo

Since I was sent the photo, I don't know the actual size of the insect.


texts: Why are mules/donkeys aggressive when faced with predators but horses are not?

texts:
I came upon an interesting quote after going down the rabbit hole on a variety of subjects. While deep in the data, I came upon this quote

  oat and farm animal owners likes to have mules with their herds because donkeys or mules will actually attack predatory animals such as foxes and coyotes.

Which raised quite a few questions in my mind. I was able to find additional sources as it relates to the predisposition of the given species.

Seemingly, donkeys and mules will act aggressively in confrontation with predators and attempt to attack to the point of killing many of them. Is there something about the physiology of a donkey/mule that makes them much less timid? Perhaps body structure? Seemingly a horse has equal or even better tools to try and defend itself.

Here are the sources (the first 2 are not the most authoritative by any means):

 Mule Behavior: Differences with horses and donkeys
Mule Facts
Donkey Behavior: A comparative study of donkey and horse behavior


texts: Can I image Coomassie and GFP in gels at the same time with a fluorescence scanner?

texts:
I'm working with a GFP-tagged protein and am routinely using a fluorescence imager (GE Typhoon) and a standard optical scanner to capture fluorescent and absorption images, respectively, of my SDS-PAGE gels.  The Typhoon supports multiple channels, so is there some way that I can scan for the two on the same device (GFP + total protein)?  I assume I can't do absorption on a fluorescence scanner..

I could manually register the two images, but it would be laborious as they are at different resolutions, slightly different rotations, and the gel can stretch ever-so-slightly when placing it on the platens.


texts: Why are hydathodes called hydathodes and not hydrothodes?

texts: I can't seem to find any etymological root for the hyda- in hydathode.  I expected the water-relater structure to be called a hydrothode, but it just isn't!


texts: Why does a coconut have exactly three "holes"?

texts:
Why do coconuts have exactly three "holes", as seen in this picture?

A theory says:
As coconut is a sibling of palm, somehow long time ago, three palms were in a same husk. Based on evolution theory, it's how the coconut was born in the world with three holes.

Reference:

"Why does a coconut have exactly three eyes?", Quora


texts: The "sweating" and leaf curl have been going on for about a week. I've done some extensive googling and have found mixed diagnoses. For context, the ambient temperature is 74°, I'm using 6,500 K lamps and there are some flies around, but they are small and seemingly harmless. The plants are about 67 days old. Pls help.


texts: Do cell membranes have more phospholipids in one layer than in the other?

texts: Assuming the cell membrane to have a spherical shape, geometry tells us that the area of the inner leaflet is smaller than the area of the outer due to the difference in radius between them. Does this mean that the inner layer has fewer phosholipids? And, if so, how does it affect the fluidity relation between the layers?


texts: Are there any papers arguing against vaccination in French?

texts:
Disclaimer: This question is NOT about challenging the safety or efficacy of vaccines. It is only asking for tips on providing credible references that may show harmful effects of vaccination, if any.

In my French class, we were asked to debate an issue in current events. My topic is vaccines in children or adults.

The challenging part is that I was assigned to argue against vaccination, and I have to back up my arguments with credible sources (not blogs) that are in French. Hopefully some of you could point me towards some links to articles or research papers in French.

Please avoid discussion on safety and efficacy of vaccines, including local and global policies on their use. I just need help with this topic for my French class


texts: Found in Russia in the kitchen. Its about 15 mm long.


texts: What type of cell do you start with in Meiosis?

texts: Okay, I was learning about mitosis and meiosis in school and had a question. I know in Mitosis you first start off with a Diploid (2N) cell and then end up with two daughter cells that are also Diploid. However, in Meiosis, I know you end up with four Haploid Cells (N), but what exactly do you start off with? Is it like a single egg makes four more eggs or something? Or does it start off with a Diploid Cell and then end up with the Haploids? If so, what exactly is the starting cell called?