texts: Alpha wave frequency variance in EEG of single subject over period of a few hours?

texts:
I have an Emotiv EPOC (EEG headset: 128 SPS, notch filter @60 Hz, felt saline contacts) I've been playing around with. Over the course of two or three hours using CCA to plot an SNR contour against frequency and time over O1, O2, P7, and P8, I noticed that a strong background signal in the alpha-wave range was existent at ~10 Hz, but then after a while of doing other things and coming back to it the strong background signal at 10 Hz disappeared but a strong background signal at a smidgen over 8 Hz was present instead.

Naturally, this leads me to ask the question: what the heck is going on? Unfortunately, that doesn't make for a good stackexchange question title, so the replacement question:

Can alpha wave frequencies vary within a single subject over the course of a single day? If they can, by how much, and under what conditions?

(if they can't, I have to start figuring out what the heck caused those artifacts...)


texts: Can twins that develop in separate sacs but share the same placenta be identical?

texts:
I have two younger non identical twin sisters. When my mum was pregnant she was told they were both in different sacs when developing but shared the same placenta.
We have done hours of research on the topic, as we have reason to believe they could after all actually be identical.
After all this research we’ve just found a load of fancy names for twins and no information on non identical twins that share the same placenta and are in different sacs.
Another thing that may help is that they are mirror twins.


texts: Is there any data to explore the heterozygosity of the South African lion over the last 18 years?

texts:
Background:

I need to find data on the heterozygosity of the south African lion over the last 18 years... and I'm struggling: so far I have found a single data point.

Question:

Where can I find data to help me explore changes in the heterozygosity of Lions living in South Africa?


texts: Is there a difference between drinking water straight from the tap compared to leaving it to sit?

texts:
An idle question - if a glass if filled from the tap and consumed immediately, it contains some dissolved oxygen from the physical process of moving through the pipes & tap. If left out (unrefridgerated) and then consumed later the bubbles are gone and there is presumably less dissolved gases.

I'm wondering whether this might have the effect of changing the relative levels of oxygen available to microbiota in the gut, and hence have some effect on the human host?


texts: What is the beneficial function of IgE antibody?

texts:
Dont tell me the "function" of IgE is to cause allergy !

In whatever texts I have seen it is  written that IgE is important to cause allergies but what is the beneficial function of IgE ? Why was it ever created ? Did it have an advantage in the pre historic ages but now causes allergies ?


texts: Question about enveloped RNA virus viral genome

texts:
I am a newbie studying campbell biology. just a quick question about virus.
When viral genome(RNA) expose itself in the host cell, why does the host cell not eliminate the genome since it apparently not belong to the cell ? Is there any mechanism that the host cell can detect and eliminate the viral genome as in the step 2,3 in the figure below ?

Thanks in advance !


texts: How common are the "common" human coronaviruses?

texts:
I was listening to a virology expert on the Swedish radio yesterday. He said that there already were several corona viruses among humans that only affected children because basically all the adults were already immune. He said that he believed that SARS-CoV-2 will be added to this category in the future, which seemed logical to me. Basically SARS-CoV-2 will at some future time only affect children and give very little symptoms because all the adults will be immune.

By googling I found four viruses listed as "common corona viruses" that affects humans:

229E (alpha coronavirus)

NL63 (alpha coronavirus)

OC43 (beta coronavirus)

HKU1 (beta coronavirus)

1.Can something be said about how "common" these viruses are?

2.I mean if an adult for some reason has no immunity to one of these viruses how long will it take on average before he gets infected?

The reason I am asking is because if we know the answer to question 2 above for the four common coronaviruses one maybe can produce an educated guess for the likelihood for a person escaping the "first wave" of SARS-CoV-2 getting infected within a given time period after we have "herd immunity" against SARS-CoV-2.


texts: What is the difference between fixation and loss of alleles in a population?

texts:
When running a simulation in PopG, with parameters:

Population size: 100
AA fitness: 1.0
Aa fitness: 1.0
aa fitness: 1.0
Mutation A to a: 1.0E-6
Mutation a to A: 1.0E-6
Migration rate between populations: 0.001
Initial frequency of A: 0.5
Generations to run: 1000
Populations evolving simultaneously: 100
Random number seed: autogenerate

I get a result of 20 populations being fixed and 10 populations being lost. Obviously, as this is a simulation, these results will vary each run; but what I am having trouble understanding is are lost populations just fixation of the recessive a allele?


texts: Can someone help me with this Pedigree Analysis?

texts:
$\text{So... here is the given pedigree chart:}$

  My question is ... whether this is an autosomal or a X-linked recessive trait.

The book I was following gave me this info:

My Attempt:

Looking at the chart ... it all comes down to either X-linked recessive or Autosomal recessive.

According to Rule 1. under these conditions:

If it appears with equal frequency in both Males and Females -- Autosomal
Otherwise , if more male than female -- X-linked

  But my teacher said ... "its not always so"

So.... I tried with both once (brute force method ... going through all possibilities) and I could not understand which one...

It seems both are correct (which obviously is not possible)

So can anyone please help me with this problem!?

Thanks!


texts:
Learning about carbohydrates, I wonder what the differences there are in terms of metabolism, and overall health between the different types of saccharides. In other words, does the body use polysaccharides, such as starches the same, or similar to how it would use a disaccharide like table sugar, sucrose?

It piqued my interest because people seem to put sugars and other types of carbohydrates into totally different categories, and one is seen as "healthy", the other "unhealthy".


texts: Prothrombin time when extrinsic pathway is turned off

texts:
I was searching for an answer that "why do we need intrinsic pathway when there is fast extrinsic pathway" and i found the answer in the following link:

http://www.pathologystudent.com/?p=3197

It says that the factor X produced in the extrinsic pathway turns off the extrinsic pathway and activates the intrinsic pathway. As the extrinsic pathway is turned off so, we need intrinsic pathway to continue the clotting process. But if the extrinsic pathway is stopped then how do we get prothormbin time because prothrombin time is for extrinsic pathway?


texts: Has there been any observation of species adapting the evolution process?

texts: I am very interested in the evolution of the evolution process itself. There are of course a lot of things that influence how evolution will work, but for this question, I am interested in things that are only related to the evolution process. Examples could be increase chance of mutations in newborns, change in reproduction age, and similar. I am specifically interested in observation where the evolution process itself has adapted to a change in the environment.


texts: What do rs id, allele coded 0 and allele coded 1 mean?

texts:
So, for a project I've been working on (different story), I've been looking at the HapMap Project, and their free online files. In their README file, they talk about how for each legend file for each chromosome/region, there is an rs id, an alelle coded 0, 1, and a base pair position.

Now it's fairly obvious after staring at this for a while that base pair position means where each nucleotide is located along the genetic sequence... is this correct?

And what do rs id, and the other words mean? Any help would be greatly appreciated!

Here's the link to the README file, in that same directory are the files about the participants, only including SNPs (snips!).

HapMap Project README file link

HapMap Project sequence data link (phase 2)


texts:
So I got the following picture and question:

a) Assume that F1 = 10 mmol h$^{-1}$ and the flow is not negative (ie f$_i$ ≥ 0,
i = 1, ..., 8). What is the most you can produce of the polymer DCDE (i.e.  determine F$_{obj}$).?

b) What can be said about the upper and lower limits of the flow values F2, ..., F8 when F$_{obj}$ is maximized?

I thought that you would want everything to flow through F4 and there onto F$_{obj}$ (where mmol h$^{-1}$ would double). However if this was true I don't understand question b, since in that case there would only be one possible flow value for F2,...,F8.


texts: Oxygen Uptake Rates in Microbial Cultures

texts:
Normally if air is sparged into a fermenter, the oxygen uptake rate is roughly equivalent to the oxygen transfer rate:

KLa(C* - CL) = Xμ/YX/O2.

How would this equation change if the oxygen became limiting (DO < 0.3 mg-O2/L)?


texts: Does a non-extinct gliding species of bird exist?

texts:
According to wikipedia was Archaeopteryx rather glider than capable of active flight. As a hunting strategy it crawl up to a tree (or other high positioned place) and glide from it to a prey.

Most of the modern birds are capable of active flight. Does anybody know if a (purely) gliding species of bird exist in present?


texts: Kinetic mathematical model of glycolysis?

texts: I am looking for papers containing kinetic mathematical models of glycolysis, hopefully in mammalian cells (or as close as possible, say yeast). The papers I have found do qualitative analysis (bifurcations, stability analysis, etc.), but do not actually fit the model to data, so you cannot be sure of the accuracy of the kinetic constants involved. The work I need to do depends critically on having reasonably accurate estimates of those kinetic constants.


texts: How many water molecules will be produced starting from acetyl-CoA in citric acid cycle

texts:
I am puzzeled by the answer. Acetyl-CoA when enter citric acid cycle, it produces 3NADH, 1FADH2, total 4 reducing equivalents. If each one makes 1H2O, then 1acetyl-CoA should make 4H2O. Why some textbooks make it 2H2O. In addition, almost like all (or many) do not balance oxygen; they say entering 16O2 and making 16H2O, so how?

Thank you.


texts: What is the function of epidermal ridges on human fingers (that produce fingerprints)?

texts: What function is served by the epidermal or capillary ridges on human fingers, the supposedly unique impressions of which are known as fingerprints?


texts: Does the Urea Cycle exist in invertebrates?

texts: Do invertebrates (like Drosophila and C.elegans) have a urea cycle?


texts: During interphase, is DNA wrapped around histones?

texts:
Are histone proteins present around DNA in the nucleus during all of interphase (including G1) or do histone proteins only form later on when chromosomes are condensing into chromatids?

Thanks in advance!


texts: Novel bacterial strains of bacteria first isolated on the International Space Station, did the space environment lead to these genetic changes?

texts:
Question
Methylobacterium ajmalii sp. nov., Isolated From the International Space Station (Bijlani et al. Frontiers in Microbiology, 12, p. 534, 2021) is a thorough analysis of "novel strains" of bacteria isolated from the International Space Station (Characterization of the total and viable bacterial and fungal communities associated with the International Space Station surfaces)
Question: Bijlani et al. 2021 is written at a very dense and technical level that is challenging for me to understand. I'd like to know:

Does the article suggests these may be newly discovered species or only that they are novel strains of known species of Earth bacteria?
Does the article suggest that the environment on the ISS selected for these species or strains, and they resulted from some genetic changes due to the ISS environment, or if we looked hard enough we'd expect to find the same ones on Earth and they just happened to be identified first on the ISS because of the rigorous studies of those samples?

Background
I was lead to the paper after seeing the ink the BBC's Could humans have contaminated Mars with life? which is primarily about a different topic.
The paper is one of 10 papers the 2021 topic Extremophiles: Microbial Genomics and Taxogenomics.
The ISS is a unique closed environment with plenty of surfaces with sometimes problematic mold growth, and a population of usually 3-6 humans with regular rotations every 5 to 6 months who maintain an array of biological experiments including a sustained effort to try to grow vegetables and flower hydroponically and in soil.
The atmosphere is maintained similar to Earth's surface (oxygen/nitrogen ~1 bar) with 60% relative humidity and often has a CO2 concentration slightly higher than the astronauts would prefer.


texts: Is pure (100% H20, (near to no) solutes) water toxic to living organisms?

texts:
Possible Duplicate:
  Death because of distilled water consumption

I know about the effects and myths about drinking distilled and/or deionized water. I'm not asking about such substances.

I wonder if a semi-immediate effect of drinking, say 1L pure 100% H2O is deadly or harmful.

My intuition says yes: either the reverse osmosis effect also present in distilled water is amplified so much that critical systems shut down due to extremely low concentrations in the organs/cells/... or the reverse happens, where the water is absorbed into cells making them burst, leading to among other things (massive) internal bleeding.

I'm particularly interested in scientific studies (if any) that were done (link to publication would be very welcome, my Web of Knowledge search-fu doesn't seem to work for this subject).


texts:
I was observing ants in my house.They all were going in a straight line and also some of the ants were coming back through the the same line.

I took some water and rubbed the line with my finger, then the ants were not able to follow each other. Looks like they were confused.

My assumption is that they may had secreted some chemical .

Am I right ?
If yes, then which chemical is that and how it is secreted?


texts: How does cell detect if a RNA polymerase II is stalled during transcription and in turn deploy the proper transcription-coupled repair factors?

texts:
When a segment of the template strand of DNA is damaged due to factors such as UV radiation, a lesion is created that would effectively block the passage of RNA polymerase II during transcription.

When such stalling occurs, a mammalian cell would usually deploy various transcription-coupled repair factor, such as the XP group of proteins to give provide a proper basis of the lesion and to orient other enzymes in. The endonuclease would cut out the damaged bases, and the DNA polymerase and DNA ligase would, respectively, add the new bases and correctly anchor them onto the template strand.

I fully realize that during the process in which the RNA polymerase II was stalled to the arrival of the transcription-coupled repair factors, some sort of cell signaling must have occurred. However, I could not find any sources that would tell me the specificity of such phenomenon. Therefore, I hope this forum could explain such matter.

Thank you very much!


texts: Through which mechanisms did the Drosophila Histone Cluster evolve?

texts:
The Drosophila Histone Cluster is a gene cluster that contains more than a hundred copies of a sequence that encodes several histone proteins. These copies are very similar.

My question is what mechanism are known that could have played a role in the genesis of this cluster?

I'm aware of the possibility of recombination, which might expand the cluster on one chromosome, shortening it on the other. Are there any other mechanisms to expand or change the cluster and are there telltale signs left by these mechanisms in the genome sequence?

Given that in most species histone genes aren't clustered, it would be weird to assume that recombination is the only mechanism to duplicate these sequences. Also, at one end of the cluster bits and pieces of histone genes are mixed with other sequences, a bit like all the broken copies got pushed to one end. It would be interesting to have an explanation for this pattern.


texts: Are there examples of animals being sexually attracted to another species more than to their own?

texts:
I just thought that from the perspective of a female domestic cat, a male bobcat probably looks like the archetype of a perfect mate. As tall, strong, muscular and mighty as it possibly gets. Clearly preferable to any of these boring male domestics.

Has anyone ever done any research on this topic, like presenting a male cat and bobcat to a female in heat and scientifically evaluating her response? (I'm not exclusively asking for cats and bobcats, but for any type of animal, and I'm just using the cat-bobcat-example to better explain the question.)


texts:
I was wondering how some animals (bulls, elephants etc.) become so large by only eating grass or plant based material and why some humans can build large amounts of muscle and mass without a proper diet.
1. How do both get their essential amino acids in order to build muscle and mass?
2. Can hormones independently build muscle and mass regardless of the food or amount of calories ingested?


texts: What is the purpose of the adrenal medulla?

texts:
The adrenal medulla is less of a 'real' endocrine organ like the others in the endocrine system and much more an extension of the sympathetic nervous system. In fact, its chromaffin cells are modified neurons by descent and secrete adrenalin and some noradrenalin upon stimulation by sympathetic preganglionic fibres, effectively turning the medulla into a sort of 'endocrine ganglion' with the whole cardiovascular system as its 'postganglionic fibres'.

Adrenalin in the circulation seems to have pretty much the same effect as all the adrenergic neurons of the sympathetic nervous system (which innervates all blood vessels, organs etc.): arteriole constriction, cardiac output increase, breath rate increase, pupil dilation, glucagon secretion and insulin inhibition, stimulation of glycolysis and glycogenolysis etc.

So what is the purpose of the adrenal medulla, if all of the effects which the endocrine adrenalin produces are essentially the same as those produced by the sympathetic mass response?


texts: Where did Neanderthals and Denisovan Man come from?

texts:
Neanderthals, Denisovans and our species (Homo sapiens) are commonly cited as closely related subspecies, even interbreeding with each other. Yet our species theoretically didn't migrate out of Africa until about 60,000 years ago, whereas Neanderthals were living in Europe a few hundred thousand years ago. Did they evolve out of Homo habilis, which migrated out of Africa before our species?

This suggests that Neanderthals must have evolved from Homo sapiens (or perhaps Homo habilis) stock in Africa before migrating out of Africa to Europe. However, conventional wisdom suggests that Neanderthal morphology was shaped by Ice Age Europe.

One possibility is that they evolved into a distinct subspecies in Africa, then migrated into Europe, where continuing evolution turned them into the familiar Neanderthals. But wouldn't this mean that Homo sapiens (the ancestor of Neanderthals) then migrated out of Africa hundreds of thousands of years ago?

Is this simply a question that hasn't been resolved, or is there a popular theory that explains the origin of Neanderthals and Denisovans?


texts:
It has a really interesting shape. Is this a common fly ?

Edit: I found this in a relative's house. For area, I can say the  plateaus and mountainous parts of Turkey's mediterranean coast. I just saw a single one of them. It was alive. The size was like 1 cm. Never saw one before in my life. It peaked my interest so I decided to ask.


texts: What are the sizes of the cells that make up human hair?

texts:
The question is in the title, but I'll explain why the question arose. I'm curious about the rates that various cells in the body divide, and have found various information relating to this, but nowhere can I find how often the cells divide in hair follicles (only that hair grows about 1 cm per 28 days, and that hair matrix epithelial cells divide very rapidly, which results in chemo patients' hair falling out). I figure that I can calculate a back-of-the envelope answer if I know the average size of hair cells. For example if they are 10 $\mu$m, and hair grows 1 cm per 28 days, then I would estimate that the relevant cell turnover time in the follicle is on the order of 1.5 per hour, assuming that the cellular division leading to the outward growth of the hair proceeds in a serial fashion. This sounds like a roughly plausible estimate, since it is significantly faster than the turnover of other cells in the human body with a high turnover (like stomach or blood neutrophils) which have a turnover of a few days.

In any case I would appreciate any insight, whether the size of hair follicle matrix epithelial cells or the cellular turnover rate in the follicle during the anagen phase.


texts: Can PolyA tails be within Expressed Sequence Tags?

texts:
Can polyA tails occur within (rather than at the end) of a sequenced tag? Consider, for example the following two sequences from NCBI:
DY008075

>gi|119423037|gb|DY008075.1|DY008075 19ACACYS_UP_022_A11_29OCT2004_095 Brassica napus 19ACACYS Brassica napus cDNA 5', mRNA sequence
TGGTACGGTCAGATGCTTGCTAAAGGAGAAATAAATAGAGACATGGGTGATAGTATAAGCGGAAAGGGAA
TGATTCAGGGTGTTTCTGCAGTGGGAGCGTTTTACCAACTGCTTAGTCAGTCCAGCCTAAGTATATTGCA
TTCTGAAGAGAAGAAACCTGTGGCTCCGGTTGAATCATGTCCTATTTTGAAAACACTCTACAAGATACTC
ATCACAAGAGAACAATCAACACAAGCGATTCTGCAAGCATTAAGGGATGAAACACTGAATGACCCAAGAG
ACAGGATTGAGATTGCACAGAGCCATGCATTCTACAGGCCTTCCCTTCTAGATCAGCCTTGATTAGTCTG
TCATGGCTCATAATCCGAACTTCTAAGATCTTACTTGTGCAAACTGCAGATTCTGCTATGTTAAACATCA
TGTCTTAAAATTGATTGTTGTTCAGCCAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACATGTC

or EE485195

>gi|126492146|gb|EE485195.1|EE485195 DHBN8DCT_UP_012_C05_25FEB2005_043 BRASSICA NAPUS SEEDS BNDH8DCT Brassica napus cDNA 5', mRNA sequence
GTTACAGCTGGTTGAGAACAGTGACAATTCCCGGTTGAGCAAAGAAATTGCAGACAAGAGCCACCAACTA
AGGCAAATGAGAGGAGAGGAACTTCAAGGACTTAACATAGAAGAGCTGCAACAGCTGGAAAAGGCCCTTG
AAGCTGGTTTGACGCGCGTGATTGAAACAAAGAGTGAGAAGATTATGAGTGAGATCAGTGACCTTCAAAG
AAAGGGAATGAAATTGATGGATGAGAACAAGCGGCTAAGGCAGCATGGAACACAACTAACAGAAGAGAAC
GAGCGACTAGGCAAGCAAATATATAATAATATGCATGAAAGATACGGTGGTGTTGAGTCGGAGAAGACCG
CCGTGTACGAGGAAGGGCAGTCGTCAGAGTCCATTACTAACGCCGGAAACTCCACCGGCGCTCCTGTTGA
CTCCGAGAGCTCCGATACCTCTCTTAGGCTCGGCTTACCGTATGGCGGTTAGAGATGGAACCATACAAAG
AAGTTCATGGAGTGAGGAGATGCTCTGTAGTAACAAGTGGCAATGTAGTAATTTCTCTTGTTTGATGTAA
GTTTTTGTCTGAGGAAGAGGTTTTCCTTTTATGTTCTCTTTGATATTATTATCTTTCTTCACTGCAAAAA
AAAAAAAAAAAAAAAAAAAAAAAACATGTC

It seems to me that both the polyA sequences at the end are some sort of tail rather than actual coding for poly lysines. If we BLAST either of the sequences, the polyA part doesn't align with any reliable nucleotide or protein (i.e., with the NCBI non-redundant databases). I can give more examples and show their best alignments to nr-Sequences but it will make the question too long.

Cross posted to SeqAnswers.


texts: Do you also consider the branch before the node as a branch? Or do you only consider the branches that are connected to leaf?


texts: Looking to understand the difference between (Fibroblast Growth Factor) FGF-2 and FGF-5

texts:
Non-biologist nor medically trained person here, but still nonetheless interested in the functioning of the human body, and more specifically, hair growth cycles.
I've read in several sources that FGF-2 is potentially a hair growth 'stimulant' (source), whereas FGF-5 is a potential hair growth inhibitor (source) and I was looking to better understand the differences between the two?
According to a basic definition, and the bounds of my current knowledge, FGF's are signalling proteins that are involved in a whole host of bodily functions including but not limited to wound healing.
What are the potential differences between '2 and '5 that makes them appear to affect hair in opposite ways, as I would have thought that the general FGF family would act in a similar way if anything.


texts: Resource for learning analysis of sequence data via QIIME 2

texts:
I am trying to study/learn metagenomics through 16s rRNA microbial data and I want to teach myself/review core biology concepts while also learning the QIIME 2 analysis pipeline, as the website suggests learning it instead of QIIME for beginners.

I found a great source : http://www.science.smith.edu/cmbs/wp-content/uploads/sites/36/2015/09/Tutorial-from-sample-to-analyzed-data-using-Qiime-for-analysis.pdf
but was hoping for something with an analysis I could actually work through on my own, as this one involves the use of a cluster, where as I only have access to a laptop of moderate power and also one that involves QIIME 2.

Also something free and maybe as hand-holding as possible would be ideal too.

As for the platform I am learning on, it is a virtual box instance of Ubuntu.


texts: Why do the proportion of predators increase at mass extinction events?

texts: Why does predation surge with mass extinction? It is caused by extreme selective pressures over resource competition that forces certain species to adapt to predatory niches?


texts: About the apoptosis mechanisms in a cell

texts:
The apoptosis mechanisms in a cell are like a type of 'self-destruction mechanism': is this correct?

As with any type of complex system with various necessary functions, if it has a set of self-destruction mechanisms for 'shutting down' the whole system, it would require some sort of 'internal programming' that can somehow 'target' each of the system's necessary functions and 'disrupt' each of them simultaneously or in some 'order'.

In other words a self-destruction system in order to be effective would have to be able to 'target' each necessary function in the system. And if a biological system has a mutation or a set of mutations that 'distort' some parts of the system then the self-destruct mechanisms might not be able to 'target' all of the functions.

So maybe the cellular mutation 'automatically' makes it hard or impossible for the self-destruct mechanisms to work. Is this possible??


texts: Is it possible for a person to become "reinfected" with the same strain of a virus?

texts: If a person contracts a virus, viral conjunctivitis for example, is it possible for the individual to become "reinfected" with the exact same strain of the virus once the person has it treated and the symptoms have gone away? I am a nursing student and am fascinated with virology, but my basic microbiology class did not go very in-depth on the subject.


texts: Why does the thickness of the Loop of Henle have to be less than the convoluted proximal tube and the distal convoluted tube?

texts:
We are currently being taught "Homeostasis through excretory system" in college. After seeing the structure of a nephron, it is not quite evident as to why should the Loop of Henle be the thinnest.
Only sense that I could make out of it is that- "Thin cross sectional area implies higher fluid velocity". Since, water and ions are majorly reabsorbed in the proximal convoluted tube, the loop of Henle is thin to increase the flow of fluid because there isn't much left to reabsorb and hence it won't require as much reabsorption time as the PCT. This decreases the filtration time and makes the process faster. I am not quite sure if this makes sense.
Can someone help?


texts: Why doesn't one develop immunity to bacterial STIs?

texts: Why doesn't one develop immunity to STIs such as Chlamydia/Gonorrhea and Syphilis even after the first exposure and treatment with antibiotics?


texts: The protein scoring methodologies ( https://en.wikipedia.org/wiki/Protein_Digestibility_Corrected_Amino_Acid_Score) rate plant proteins of a lower quality than animal proteins. Now I can understand the reasoning that proteins have a lesser quantity of essential amino acids (allegedly) making them "lower quality" in terms of protein; but I don't see why there should be a difference in digestibility between plant and animal proteins (I can give links but it's common knowledge that plant proteins are less digestible). What is the basis for this difference in digestibility ? Whatever the amino acid composition, I don't see how that would affect digestion of proteins. So why are plant proteins considered less digestible ?


texts:
What is the fungus pictured below? The photo was taken October 6, 2013 near San Antonio, TX.

I have Googled it and my results suggest Laetiporus root rot (Laetiporus sulfureus).

According to this website the presence of this fungus indicates the tree should be removed.

Is there any chance that this is something else? I would hate to remove such a beautiful oak tree.


texts: Can storing food in a de-pressurized container result in anaerobic bacteria growth?

texts: I was looking for a way to store for longer some products which go bad quickly. I found a stainless steel container made with a hermetic lid that you can remove air through (using a pump) so you create a vacuum of sorts (I don't know to what level can the internal air pressure be reduced). The issue is whether storing food which isn't specially sterilized, such as vegetables or spices, can result in the growth of pathogens such as Clostridium botulinum? What I originally looked to buy such a container for is soy lecithin, as I read these go bad very quickly even if stored in a cool, dry place as advised.


texts: Slow-oxidative fibres vs fast-glycotic fibres

texts: Why do slow oxidative muscle fibres contain more mitochondria compared to fast-glycolytic muscle fibres?


texts: Meaning of "primers IL-2" in a scientific article

texts:
From an article ("Amelioration of Experimental Autoimmune Encephalomyelitis in Lewis Rats by FTY720 Treatment", 2003):

  We performed PCR amplification in a 100-μl reaction mixture containing 200 μM of each of the regular dNTPs, 10 pmol of each primer, and 2.5 U of TaqDNA polymerase (TaKaRa) using primers IL-2 (300 base pairs; bp), 5′-CAGCTGTTGCT GGACTTACAGG-3′ and 5′-CACAGTTGATGGCTCATCATCG-3′; IL-6 (294 bp), 5′-GACTTCACAGAGGATACCC-3′ and 5′-TAAGTTGTTCTTCACAAACTCC-3′; INF-γ (310 bp), 5′-GGATATCTGGAGGAACTGGCAAAAG-3′ and 5′-GCTAGATT CTGGTGACAGCTGGTG-3′; β-actin (461 bp) 5′-CATCGTGGGCCGCTCTAGGCA-3′ and 5′-CCGGCCAGCCAAGTCCAGACGC-3′.

I'm not completely sure: do they mean that the primers are "specific to the IL-2 gene"?

Do they mean "5′-CAGCTGTTGCT GGACTTACAGG-3′ and 5′-CACAGTTGATGGCTCATCATCG-3′ are primers that are specific to the IL-2 gene"?


texts: Cholesterol and fatty acids role in bile?

texts: The composition of gallbladder bile is 97% water, 0.7% bile salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids and lecithin)1. Bile's role is mainly help for digestion of lipids via bile salts and acids (emulsification) but i dont understand what is cholesterol and fatty acid role in bile. What is cholesterol and fatty acid's function in bile?


texts: Have there been any theories put forward as to the reasons behind Temperature-Dependant Sex Determination in reptiles?

texts:
This applies to most if not all reptiles, but I'll write about leopard geckos since that's what I know.

Incubation temperature of the eggs makes a big difference in the development of the gecko. Obviously excessively high or low temperatures will kill the embryo, but inside the safe temperature range there are some interesting effects. The most well-known is Temperature-Dependant Sex Determination (TDSD).

Studies have been done and it is quite well-documented that:

Incubating eggs at the mid-point of the safe range results in predominantly male offspring.
Incubating eggs at the high or low end of the range both result in predominantly female offspring.

According to my gecko book, there are also some interesting effects regarding males that hatch from female-biased temperatures being more sexually active but less aggressive to females than the "macho" males produced at male-biased temperatures, females at female-biased temperatures being the most fertile and high-temperature females being more aggressive than lower-temperature females.

(Incubation temperature also affects colour - specifically melanin production levels. AFAIK it's not known whether this is a direct effect of the temperature or an indirect effect from the changes in sex hormones at the different temperatures. It's probably a different enough issue to warrant a separate question, though.)

Going back to TDSD, my question is: what theories have put forward to explain this sex determination? Evolutionarily speaking, how did this come about? Are males less likely to survive so they are only produced at safe temperatures? Does the optimal male:female ratio for propagating the species change in adverse conditions?

I'm not looking for random guesses. I'm interested in knowing if there have been any theories put forward from knowledgeable and reputable sources.


texts: Are there human cells, apart from red blood cells and platelets, without a nucleus?

texts: I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells?


texts: Found this algae in a small stony stream that feeds a medium sized river. I can not identify either of the filamentous algae in this photo


texts: In the condition of hypothyroidism the Thyroid Stimulating Hormone level is high in individuals. What signalling/metabolic pathway mediates this sensation of pain which is mostly experienced in feet and joints.


texts: Do I need to use the same WT C57BL individual for back-crossing or can I use a new one for each generation?

texts:
I've just received heterozygote C57BL mice from COMP and I need to start back-crossing them. I've read many colony management protocols, but couldn't understand if I need to use the same WT mouse for all ~10 generations of back-crossing or use a new one for each generation.
Thanks!


texts: How do the quantities of ATP formed during aerobic and anaerobic respiration compare?


texts: Are genes uniformly dispersed throughout the genome?

texts: I think that telomeres and centromeres are regions with a very low gene content (= regions that contain few genes). To the exception of telomeres and centromeres, are genes uniformly distributed throughout the genome or do they tend to clump together or to scatter as much as they can? Do genes tend to clumped or avoid specific regions such as regions with low mutation rate or low recombination rate?


texts:
I have come across an insect in Cambridge UK that I could not identify.
I tried to find this in various catalogues of local insects without success. The insect was about 1-2cm in length and didn't move at all until it was disturbed. I found it around 11am. We are currently experiencing high temperature variations (8C-20C).
Could someone please help identify it and point me at any useful resources I can use in the future?


texts: How useful are vitamin and trace element additions in E. coli culture medium?

texts:
In protocols for minimal media for growing bacteria I often see that a vitamin mix or a mix of various trace metals is added. But at least for E. coli I know that those are not strictly necessary, they also grow in minimal medium without any of this.

Does it make sense to add vitamins or trace elements when growing common E. coli for protein expression like BL21 (DE3) in minimal medium? Is there some literature data on how this can affect the growth of the bacteria?


texts: Why do some trees hold their leaves through fall and winter?

texts: Why do some species of oak (Quercus spp.) retain their leaves through fall and winter?  I've found that these leaves are called marcescent leaves. There must be some benefit that the tree gains from this because it seems like it would increase the possibility of limb damage due to snow accumulation on the leaves.


texts:
I know that being heterozygous or homozygous recessive for the MTHFR gene prevents that person from being able to process and use folate and B-12. It causes an unhealthy level of homocysteine to accumulate in the bloodstream which can cause more serious problems. Taking methylated B-vitamins, specifically Methylfolate and Methylcobalamine will prevent homocysteine from building up, but I am not sure why.

Can someone explain how this process works? I am wondering how the body uses folate and B-12 (cobalamine) normally and how the recessive MTHFR genes interfere with this process.


texts: Following DNA replication during S-phase of the cell-cycle, are all genomic regions subjected to the same stringent level of DNA-Repair?

texts:
To my (limited) understanding, there are 2 main ways that mutations can occur in DNA: Environmental (UV, etc) and mistakes during cell division.

I was wondering if there is a mechanism that can give priority to certain genes to be accurately duplicated. Some sort of trigger that says "double-check this specific gene before continuing with the duplication".

And if there is such a mechanism, then I wonder if there is some sort of dependency system for genes that control groups of other genes. So that if a certain gene "activates" the double-check trigger, it would automatically add that trigger to the group of genes which are affected by it.

Thanks.


texts:
Recently I was reading about myopia and I understood a few basic facts about it:

Its initial cause is a constant spasm in the ciliary muscle.
To do less work, the eyeball elongates a tiny bit.
During adolescence, because of the growth of the body, the eyeball elongates accordingly even more (i.e. the myopia is progressing).

I don't really understand the exact mechanism responsible for the transition from 1 to 2. Is the ciliary muscle capable of elongating the eyeball on its own, or is there some other relationship to another part of the eye?

It's weird how myopia is so common these days and I wasn't able to find the precise mechanism behind it.


texts:
I’ve seen many textbooks saying that LH surge occurs in the Follicular phase while others say it occurs in the Ovulatory phase.

I’ve tried googling this, only to end up knowing two things:
1) It occurs 2-3 days before ovulation and 2) It occurs in Ovulatory phase.

Doesn’t that two contradict each other?

If you see the hormonal variation graph, LH surge occurs somewhere between follicular phase and Ovulatory phase. This is quite confusing.

So, at what phase does LH surge actually occur?


texts:
I just stumbeld across a picture and wonder which species it is?

I took the below picture of a bird, probably a raptor, in mid-January 2011, 7 pm, on the Annapurna Trek in Nepal. My altitude was around 2000 m.

Since I took the picture a long time ago I cannot recall any information about the size.


texts: Are genetic crosses between asexual organisms possible?

texts: To my knowledge (Please correct me if I am wrong), genetic basis is the key in defining species. When we encounter an unknown species, we can sequence it's genome and compare the genome with other known organisms from the genome data bank and see if there is a significant similarity. If no significance were found then we can call it a newly discovered organism. Also careful study of genetic crosses between species pairs and partially isolated sub species to identify general patterns in the genetics and origin of reproductive isolation helps to answer the question of speciation. Then how would we cross asexual organisms like many bacteria or protists? Is it possible to cross asexual organisms? If not, how do scientists study their genetics and define species of asexual organisms?


texts:
As far as I am aware, most of the central nervous system consists of myelinated axons and most of the peripheral consists of unmyelinated.

What is the reason for this?

Would it not be more efficient to have them all myelinated?


texts: What evidence is there on the medical effects of circumcision?

texts:
If this is the wrong place to post this question, then I will delete it and post it were it belongs.

I have heard many conflicting things about circumcision.  I have heard that it reduces the rate of STDs, including AIDS, and cancer in the man and his wife.  On the other hand, I have also heard that circumcising babies can cause psychological harm and increases the rate of urinary tract infections.  Are there any reliable studies on this issue and what do the conclude?

Thank you for any and all answers.


texts: Which statements are true regarding an energy pyramid?

texts:
The number of producers is greater than the number of primary consumers.

The amount of energy at the primary consumer level is greater than the amount of energy at the secondary consumer level.

The number of primary consumers is less than the number of secondary consumers.

The amount of energy at the producer level is less than the amount of energy at the primary consumer level.


texts: How is the GenBank used in typical biological research? According to the GenBank statistics, the database contains about 100 million sequences. I find it difficult to understand why is all that data needed. To make the question less broad, what are the most common use-cases? Check if someone already sequenced DNA of some plant or animal?


texts:
There are a lot of publications, starting from 2000, about using telomerase for targeting cancer cells (it is upregulated in more than 80-90% of tumor cells). Specifically using its promoter (hTERT). In all publications, researches talking about the success of this approach.
So my questions,  why there is no use of this? What is the problem? I read a lot of articles - and didn't find an answer.

http://scholar.google.com/scholar?q=telomerase+suicide-gene+promoter

http://www.spandidos-publications.com/ijo/21/3/661  (one of the newest)


texts: Monochromator in fluorescence microscopy

texts:
I'd like to ask why are there no fluorescence microscopes that use a monochromator instead of filters?

If there are any, then I should change my question as, which ones use it and why are they so rare?


texts: How does laser surgery correct accommodation problems?

texts:
When someone undergoes laser surgery to improve eyesight, how does it correct accommodation problems?

Why does it not help presbyopia?


texts: What is the difference between options protein and replication in the NCBI database?

texts:
After checking the NCBI help page, I am still unclear about the difference between protein and replication interactions for HIV.

http://www.ncbi.nlm.nih.gov/genome/viruses/retroviruses/hiv-1/interactions/


texts: Inspired by the post about extracting pet DNA, how long would genomic DNA be stable for in a -20°C freezer? It is common practice to store DNA (double-stranded, plasmid) in a -20°C freezer in the lab, but would genomic DNA last longer in a -80°C freezer? With either method, how long would it be stable for?


texts: Can the sulphur content of biological material be reliably calculated from fat, fibre and protein contents (Weender Analysis)?

texts:
An often-used analysis of feedstocks for lifestocks is the Weender analysis, which basically divides the volatile solid content into fats, fibre and protein, as well as N-free matter. I found no English language article on the process.

The individual values and how they are arrived at are:

Fat: anything dissolvable in organic solvents;
Fibre: anything not dissolvable in acids or bases;
Protein: N-content times 6,25 or 6,38 for plants or protein (and the N-content in protein is most of the times close to 16%);
N-free: the rest (sugars, starch, pectines, organic acids ...).

This data is often more readily available than a full chemical analysis.

I want to know the sulphur content - can I reliably say fats contain v mass-% sulphur, proteins x mass-% ... and so on?
If yes, would this be applicable to manure also?


texts: What is meant by single molecule sequencing?

texts:
When sequencing papers refer to single molecule sequencing, what is their definition of a "molecule". Are they saying base by base? The entire DNA chain in a chromosome can also be though of as a "molecule". In that case, that's a much larger read. What's the default interpretation?

For instance, is the Illumina sequencing "single molecule" as they fluoresce one base at a time?

Thanks!


texts: Collective term for both exons and introns

texts:
Is there a term I can use to refer collectively to both exons and introns? By collectively, I don't mean ligated as with an unprocessed transcription product. I'm just writing about exons and introns and getting frustrated that I keep on having to write "exons and introns", wishing there was a more concise term I can use in the place of that phrase.

For example, the term I am looking for would fill in the following blank perfectly.

  The gene has 5 exons and 4 introns, so it has 9 _____.


texts: Term for trait that is advantageous to a population only as long as it is rare

texts:
I remember reading about a concept—in evolutionary biology or natural selection, I think—whereby a particular trait is advantageous to the population or species but only so long as that trait is only exhibited by a minority of the population. That is, the population is more likely to survive if the trait's existence and expression is maintained, but only if that expression is limited to a small percentage of the population. If the trait becomes too common, the selection advantage of having it will decrease, and the fact that most of the population has it may even negatively impact the survivability of that population.

I can't recall where I encountered it. It may have been in the context of reading about ADD, Aspberger's/Autism, neurotypicality, introversion, or mania/OCD. I want to revisit the topic and learn some more about it, but Google is failing me.

Can anyone tell me the name of or term for the concept I'm thinking of?


texts: How does hair grow and is it similar to how grass grows?

texts:
If I recall correctly, nails (finger nails or toe nails) grow by adding matter at its base. So for instance, if you would draw a dot at the very bottom of your nail, it would end at the top in a couple of weeks.

I was wondering how this works with hair. Is new hair added at the bottom and the old hair 'pushed' away? Or does hair consist of layers that always try to get further and further (that would mean longer hair is thicker than shorter hair). And is this wayof growth similar to how grass grows?


texts: What is this 2-3cm insect found in Slovakia?

texts: Noted in the West Slovakia at the garden


texts:
I think I have a wrong concept about viral mutation process. First of all what is mutation actually? I mean, I know it's a sudden change in DNA, happening when subjected to mutagenic agents.

But can it occur due to internal urge of an organism, say virus? If not then how can virus like Ebola undergo rapid mutations so that no vaccination can be given as specificity for antigen is lost?
What accounts for such a viral behaviour?

In evolution, internal urge for survival causes development of  some beneficial characters. What is meant by this at molecular level. like gradual mutation!!


texts: Can anyone help identify which insect is this?

texts:
I know this may not be the right forum for insect identification, but I couldn't find any reliable source of information. Please bear with me

The insect was found on my front door, total length may be about 2 rice grains

You can see wings and slender legs behind the body

I live in India, if it matters.


texts: Are there bacteria that respire anaerobically in aerobic conditions?

texts:
There are facultative anaerobic bacteria that switch to anaerobic respiration in an anaerobic state, but are there any organisms that would still perform anaerobic respiration even when shifted to aerobic conditions? Obligate anaerobes would die when introduced to an aerobic condition right? Are there any which can survive?

This doubt came into my mind while reading the Hugh-Leifson Oxidative Fermentative test. Such a bacterium would be read false positive for oxidisers in such a case because it would ferment glucose even in aerobic conditions.


texts: How much food can an average person eat, and which animal is that equivalent to?

texts:
When the average person overeats, how much food can he eat in a day? Which animal's average meal would that be equivalent to?

When documentaries are talking about animals feed, they usually say something like "The fish can eat 500kg of prawns in a day!" But when it comes to humans, they calculate in calories. Which animals are we closest to in terms of capacity?

Note: I think I can be slightly loose on the definition of overeating here. It can mean eating beyond the point of feeling full, or the human maximum stomach capacity.


texts: Isolating gene of interest from a large strand of DNA

texts:
I was always confused about this in class and never learned it fully.
So say you have 10,000 bp of DNA and you just want to isolate 100bp of specific region(gene of interest) using restriction enzyme.

How can you ensure that at the both ends of your gene of interests has the right sequences for certain restriction enzymes to cut.


texts: What's the worst that can happen from too much sleep deprivation? Can you die?

texts:
It is well known that sleep deprivation causes considerable discomfort in humans (and has even used as a form of torture), but nevertheless there have been people who went through protracted sleep deprivation, apparently with no long term consequence.

I've noticed that sleep deprivation seems to trigger an intense sense of "this is bad for me" - yet given the apparent lack of ill effects (beyond the obvious) I cannot say whether this is merely anxiety over discomfort, as opposed to a genuine perception of physiological damage.

What if you were to go without sleep for as long as possible, despite the discomfort? Is it possible to commit suicide in this way (and what would be the cause of death)? Would you fail because you eventually ignore whatever stimulus was preventing sleep, and sleep anyway? Would artificially counteracting the temporary debilitating physiological effects (such as loss of body temperature) allow you to survive sleep deprivation of arbitrary length?


texts: How do the CFTR alleles interact within an individual with Cystic Fibrosis when mutations of different classes are present?

texts:
So mutations in CF are classified by the severity of the impact on the production of the CFTR.
But an individual may have two different CFTR mutations.
I assume that the least severe mutation of the two is the most relevant to the phenotype. e.g It is more favourable to have a class I and class II mutation that to have 2 class I mutation.
However, I cannot find any references to support this or explain the molecular interaction between classes. Additionally, I fear that it may be more complex than this.
The purpose for knowing this is I want to control for CFTR class in regression analysis but I am removing individuals on ivacaftor or similar so I am talking about the effect purely at the baseline biological level rather than differential access to potentiator therapies.


texts: Is there a mechanism by which mammals lose interest in a partner after mating?

texts:
I'm reading the book called "Cupid's poison arrow", which revolves around a rather simple assumption: most mammals, including humans have a genetic program that is responsible for ever increasing dissatisfaction with a mate after intercourse with orgasm.

The book proceeds to give a number of examples, here's what I remember:

Coolidge effect, where libido is revived upon exposure to a novel, receptive partner.
Male rate copulating on average 8 times with a receptive female before losing interest
Sexual satiety setting off a 14-15 day hormonal cycle where [a male rat] would lose all interest in a partner

The book contains a large amount of anecdotal evidence of humans experiencing negative outlook on their partner after orgasmic intercourse, with more intense intercourse producing more intense dissatisfaction.

The author proceeds to formulate a hypothesis that humans and other mammals have a genetic program that fosters sepratation between mates and seeking of a novel mate as a mechanism to promote more genetic diversity in offspring (as opposed to monogamy)

Is there a scientific basis for such claims -  do mammals have a mechanism that draws them apart after intercourse or sexual satiety is achieved?


texts:
I was wondering How long does it take for a tardigrade to enter and exit the Tun state?

I'm doing a thesis on tardigrades for my B.S in biology and I haven't come along any information in the primary literature talking about how long roughly, it takes to enter the tun state in cryptobiosis. I understand that it takes a couple hours for it to pop back up again, but what about entering?


texts: In scuba diving, are nitrogen narcosis and high pressure nervous syndrome the same thing?

texts: In training for scuba diving, they tell you that when you're bellow 100 ft or so you have to watch out for changes in mental state that resemble drunkenness. The cause of these mental disturbances is called nitrogen narcosis, and it has something to do with the increased pressure on the nitrogen component of the gas that you're breathing out of your tank. I just read this article from the what-if section of XKCD (halfway down the page, under the header about Michael Phelps) that mentioned a very similar sounding disorder called high pressure nervous syndrome. Are nitrogen narcosis and high pressure nervous syndrome related, or are the effects of high pressure nitrogen and high pressure by itself separable?


texts: How to make GABA pass the blood brain barrier?

texts:
I thought of methylating GABA at the gamma amino group in order to make it pass the blood brain barrier, but would it work?

The goal is to make a sedative. Like GHB or benzodiazepines (I know that benzos have a totally different structure)

Any ideas on how to make GABA  pass the blood brain barrier?


texts: I heard and read telomere 'health' or 'length' ( if that's right ) has alot to do with cell 'health'. If telomere 'abilities' are 'restored' to a 'healthier' status then the cell it is in functions as though it were 'younger'.  I was wondering since cancer cells grow without limit and 'older' cells or unstable cells grow with less ferver do cancer cells have functioning telomeres within them and would they somehow be alot more 'robust' then telomeres in normal cells? If this is true could telomeres from cancer cells somehow revitalize the telomeres in normal cells?


texts: Do hornets remember and recognize a human? Do they have any (kind of) memory?

texts:
hornetology
So it happens that a hornet (vespa crabro) flew inside my house today and now is being held in a plastic container (I made some holes to let it breathe). But it also happens not just this once, but twice and I guess it's not over (we live by a small forest, probably it builds its own nest there). I wonder if hornets may have some memory - can it  remember and later recognize a human?
And if I take it to another place of the town I live in and let it go there will 'he' come back, 'cause it will remember where 'he' lived before?
Thanks for any advice, I just don't want to simply kill it... 'him'.


texts: Are the inverse problems of Systems Biology impossible to solve?

texts:
I have heard Sydney Brenner give a talk [0] on how the entire program of Systems Biology is suspect because, according to him, a chap named Hadamard showed that inverse problems are impossible to solve, or something to that effect.

I find it somewhat odd that no one seems to be paying any attention to this, and many are blithely carrying along trying to reverse-engineer biological organisms. I personally think that this reverse-engineering effort has its place, but Sydney Brenner doesn't seem to think so, and advocates tackling only the forward problem. Here's an excerpt from an abstract to a similar talk of his:

  ... This notion of computation is, in my opinion, the only valid approach to biological complexity and is opposed to many of the ideas underlying what has come to be called systems biology, which is very fashionable today. It will be shown that systems biology attempts to solve inverse problems — that is, obtain models of biological systems from observations of their behaviour — whereas, what I call computational biology, continues in the classical mode of discovering the machinery of the system and computing behaviour, solving a forward problem.

Is Brenner simply wrong on this or is there something to his objections?

[0] Sydney Brenner, Much ado about nothing: systems biology and inverse problems, 2009.


texts: Books on population or evolutionary genetics?

texts:
I have recently been involved in collaborations that require me to model the population genetics of eukaryotic populations. I fear I may either be "re-inventing the wheel" or making conceptual mistakes (e.g. simplifying assumptions) in many of the techniques and decisions so far.

I would very much appreciate recommendations of books about population/evolutionary genetics or micro evolution to deal with these fears. Preferable criteria are:

Intuitively introduces key concepts.
Emphasis on modelling with examples of problems and their solutions.
Relatively short (I'm planning to read from cover to cover).


texts: I understand that glucose is soluble and hence it is not stored by cells. However, my teacher said that I also have to say that "it would have an osmotic effect on the cell." I don't understand what that means.


texts: Why is the GULO pseudo gene expressed in humans?

texts:
The GULO pseudo gene is being expressed in humans according to Genecards.

Why is this still taking place after tens of millions of years since then gene lost the capacity to encode for a functional enzyme?


texts: What is the name of this beautiful insect?

texts:
I spotted this magnificient looking insect last night in my house in Singapore. It was around 1.5 inches long and had a silverish golden back with long legs and antennae.

 ^ Click for full-size, higher-quality image

 ^ Click for full-size, higher-quality image


texts: What species is this marine invertebrate sighted 2m below the surface near Halifax, NS?

texts:
This image was taken at ~2m depth, with a small ROV in Halifax, NS in May. We're in the Northwest Atlantic Ocean and as far as I know, don't have gooseneck barnacles.

Considering that it may be a polychaete worm as several other species were sighted during same dive (Tomopteris ?, Chaetopterus) and the fan appears to have more than 10 appendages. Possibly a sabellid or goblin worm?

Sizing is difficult to estimate but ~5cm in length.

Adjusted, enlarged version:


texts: How can there not be purpose movement in the fetus until week 18, when a fetus can open its mouth and suck its fingers at week 11?

texts:
According to Fetal Movement

  According to an overview produced by the Royal College of Physicians
  of Edinburgh, purposive movement begins at about 18 weeks, gradually
  replacing reflex movements

but in the same article says

  At week 11, the fetus can open its mouth and suck its fingers; at week
  12, it begins to swallow amniotic fluid.

I highly doubt that open a mouth and suck its fingers can be classified as "reflex movements", then how it is asserted that there is not purpose movement in the fetus until week 18 when a fetus can open its mouth and suck its fingers at week 11?


texts: can you tell me what kind of animal this is?

texts: I found this skull over 2 years ago and i have been unable to find another like it or even come across someone who knows what it is. i live in south mississippi and the animal it came from looked like a deer, or even a dog, it was almost completely decomposed. I have been curious for 2 years now and have posted this before on other sites with no luck. someone help please .


texts: How does the symbiotic bacteria reaches a human caecum

texts: My thought on this matter is that we have got a very high pH of about 1.8 in our stomach.So,most of bacteria who came in through food or just open mouth should be killed by it.So,how does a bacterial fauna builds up in caecum.


texts:
What is this insect? (Location: Bangkok, Thailand; found on a rambutan; size: 8 mm long, 4 mm wide; color: black)

On the rambutan:

Videos:

https://youtu.be/WwB0B_PdOT8
https://youtu.be/0DZ8nXcJIkI


texts: Why do our eyes "wrap" hue from UV to IR?

texts:
On the high-wavelength side of things, we see almost-infrared as reddish, with a slight tinge of magenta. On the low side, we see violet fading into the same magenta color. Why is that?

You can see it clearly on any hue chart. There's an unbroken flow from one to the other, even though the wavelengths are literally as far apart as they can be while still remaining visible.

I understand that color vision is limited due to several biological factors(cone receptivity, absorption, etc), but why do the colors on both side fade into each other? Is it just our brain making things "neat" and continuous?


texts:
I have green insects that eat the leaves of my gooseberry plants:

Location: Toronto, Ontario.
The insects seem to only eat the leaves of the plants (not the fruit).
They have been present since mid-May, and I expect that they'll be present until mid-June, based on past experience.
They do not have spots.

What is the name of this insect?


texts: What is the effect of the wavelength on the spectrophotometric measurements of protein?

texts: Does the wavelength setting affect the absorbance reading of a spectrophotometer? For example, if I am using a spectrophotometer at 550 nm to determine the protein concentration of my samples, would my results be different if I analyze them at 500 nm?


texts: What are the effects of removing CD4 receptors?

texts:
If the gene for the CD4 receptor was removed, would the person's immune system work normally?  Could a new artificial receptor be substituted in place of CD4?

Could HIV infection be prevented in this way?


texts: How does Temperature influences the rate of protein turnover?

texts:
Question

How (quantitatively speaking) does temperature influences rate of turnover of transcription factors?

Which protein?

As I am not looking for any accurate number I am talking about an "average" transcription factor. I leave to you the choice of answering this question with some very accurate example (Transcription factor GTF II A for example) or with some broad observation on how temperature influences protein turnover.

The organism I'd like to model is a typical unicellular eukaryote such as a yeast for example that lives at "standard" range of temperature (between 5°C and 35°C roughly speaking).

Of course, I am not interested in considering a transcription factor that is directly involved in some response to a change in environmental temperature. I am interested in transcription factors which are involved in developmental pathways that have nothing to do with reaction of the body to temperature.

I am looking for a referenced answer $\ddot \smile$


texts: Are all body atoms really recycled several times during a life?

texts:
I heard a point, that all (human) body atoms are recycled withing short period like few years. Recycled means "old" atoms are replaced by "new" ones during metabolism, leaving only structure unchanged.

But this looks contradicting with knowledge about DNA. DNA molecule looks unchanged and the fate of all it's atoms looks known.

Yes I know there are some spontaneous damages which are repaired, but most of DNA atoms remain in place. Even during cell division, 50% of atoms goes to one of the descendant cells. I.e. they don't go outisde body.

So, if the point is wrong concerning DNA atoms, then may it is wrong at all?


texts:
The (human) genetic code encodes 20 amino acids. They form a protein using peptide bonds. Each amino acid has a carboxyl group (COOH) and an amino group (NH2) that can potentially form a peptide bond.

Source: The Culture of Chemistry

Does this property of amino acids means that each amino acid can form a peptide bond in any combination? In other words, are there certain amino acid doublets in existence that never pair up?


texts: Estimate sex-specific survival from mark-recapture data using multi-site, sex-specific cormack-jolly-seber model?

texts:
I am interested in identifying sex-specific survival rates. I have a long-term dataset of individually marked birds from one breeding colony. Of these, I am able to genetically sex a subset. Additionally, I have access to mark-recapture data on nearby breeding colonies and so can estimate emigration from my target breeding colony. However, I am only able to sex individuals from my focal breeding colony.
My research project addresses both survival and dispersal (permanent emigration). So I'd like to disentangle these as much as possible and look at effects of sex. One approach is to only model the subset of birds I'm able to sex. Another approach would be to model all individuals, including unknown sex, and apply the techniques in Nichols et al. (2004) to apply probabilities of "male or female" to unknown-sex birds (I may be summarizing that poorly).
Can I use a multi-site model if I only include individuals marked on one colony, but do have data for permanent emigration to other colonies? Would it make sense to use a multi-site model with all individuals from all colonies but only have sex information from one colony?
Thanks in advance!
Nichols, J.D., Kendall, W.L., Hines, J.E. and Spendelow, J.A. 2004. Estimation of sex‐specific survival from capture–recapture data when sex is not always known. Ecology 85(12):3192-3201.


texts: What is the evolutionary significance of germ cell migration to gonads?

texts:
Why do germ cells have a different origin than the gonadal organs? Does it help the animals in any way?

P.S. I know it is difficult to answer whys in biology but is there any theory as why do they have different origins.


texts:
Last week-end I was working in my parent's garden and when I dig a bit the ground, I found few larvas I never seen before. My father told me there are there every time when he's doing the garden springtime.

I took some pictures (I just put it on leaves for the picture to see better than on the ground).

One low-res:

And the gallery hi-resolution pictures

The location is in northern of Switzerland (Jura) at around 700 meters above the sea and the larvas were inside the ground in around 3-5 centimeters (1-2 inches) deep.


texts:
I found this spider today and I'm curious to know what it was.

Discovered today at 14:27 CEST, about 200 meters from Hamr pond, Prague, Czech Republic. It may have been carried all the way from the pond.
Body length cca 5mm (cf. photo #2 - reference object is a 5 CZK coin, 23mm in diameter according to Wikipedia)

Initially swept off my shoulder (white T-shirt), to which it succeeded in attaching, and began descending on a thread. After it was placed on a small ledge, it began climbing the adjoining wall. After some convincing to stay in place (using my finger as an obstacle and a little physical contact with its legs), it lifted its four front legs, so I left it alone.

I didn't manage to get good sight of its eye pattern, but it did appear to be consistent with the eye pattern of huntsman spiders - the sides of its face were black with a brighter region between. I was unable to determine the quality of its eyesight either, though it did not object to placing the coin nearby to it.

Wikipedia page on huntsmen living in Europe lists nine species, but none of those that had photos included matched in appearance.


texts: What does "each pathway define an independent genotype" mean?

texts:
In a section of this paper.

  However, if the question of independency is posed in the
  form: “Does each pathway shown define an independent
  genotype?,” then each of these three pathways is indeed
  independent. This is the way that MPS defines the independence
  of pathways.

What does “Does each pathway shown define an independent
genotype?,” mean?


texts: How can a homozygous mutation, considered pathogenic, occur on a gene such as HFE without the disease developing?

texts:
What happens when you have a homozygous mutation on a gene (eg. a swapped base), that is considered pathogenic, but without developing the disease?

It it were a heterozygous mutation I would get it, because we still have at least one healthy/wild-type copy of the gene, so at most the disease will just manifest in a more mild form, but with a homozygous I have no idea how is it possible to NOT develop the disease.

Also, what happens when heterozygous mutations develop the disease? In these cases why does the healthy version of the gene goes "quiet"?

One example is HH caused by HFE gene mutation (mostly C282Y and H63D), and not everyone develops the disease, doesn't matter if they are heterozygous or homozygous.


texts: Preventing Diabetes by preventing stress?

texts: I have came to know that taking a lot of stress increases the risk of Diabetes, and patients of Diabetes are adviced not to take too much stress, am i correct? if yes then I am unable to understand that how stress affects the level of glucose in our blood?


texts: Does a mydriatic drug neutralize the action of a miotic?

texts: If a person were administered a mydriatic, would the subsequent application of a miotic neutralize the action of the former? If the sequence were reversed would a mydriatic neutralize the effect of a miotic?


texts: Osmoregulatory Acclimatization in amphibians

texts: If a frog is gradually exposed to increasing concentration of salts can they acclimatise or will they die of exosmosis ?


texts: How many people in the world have bad eyesight?

texts: I was watching this ted.ed episode and heard it was around 500,000 but that didn't sound right-- does anyone know?


texts: Biological basis of the science fiction story "The Dipteroid phenomenon"

texts:
The science fiction novelette by Poul Anderson The Dipteroid Phenomenon describes a plot in which

   the protagonist Evalyth is one of the members of a space-faring civilisation which is rediscovering atavistic humans stranded on other planets following the fall of human civilisation from an interplanetary war in the past.

  The husband of the protagonist is murdered and cannibalised by the savage guiding him through the jungle, and she finds and captures the savage's whole family in revenge, intending to execute the savage. While doing so, she discovers that all of the humans on the planet, including the civilised city-dwellers, have a tradition of cannibalising humans. The savages hunt each other for cannibalism, while the city-dwellers hunt down the savages, which they then keep as slaves for consumption.

In the end of the story, it is revealed that:

   all of the male humans on the planet are unable to sexually mature normally due to a genetic mutation in their Y-chromosome, which results in them having to consume male genitals in order to reach sexual maturity.

The novel then further states that the phenomenon of having to consume males in order to mature is also found in terrestrial Diptera flies.

  'Hence a dipteroid phenomenon may have appeared in man on this planet. Such a thing is unknown
  among higher animals elsewhere, but it is conceivable. A modification of the Y chromosome would
  produce it. The test for that modification, and thus the test of the hypothesis, is easily made.'
  The voice stopped. Evalyth heard the blood slugging in her veins. 'What are you talking about?'
  "The phenomenon is found among lower animals on lower worlds,' the computer told her. 'It is
  uncommon and so is not widely known. The name derives from the Diptera, a type of dung fly on Old
  Earth.'

Is this "dipteroid phenomenon" a real biological phenomenon observed in Diptera dung flies on Earth? I was unable to find a scientific paper describing this rather interesting phenomenon.


texts:
Can anyone help me in understanding how backcrossing helps hybrid to achieve pureline?

I have been looking into the references i possess but couldn't seem to find anything


texts: Do lower animals have instinctive behaviors?

texts: Can an organism such as C. elegans, with only 302 neurons, exhibit "instinctive or innate behavior"? If not, then at what basic minimal structure is instinct manifest?


texts:
I have found this plant in Trabzon, a city in Turkey. I found it near the highway. I assume it isn't planted intentionally, but maybe left after previous ornamantel plantings. It smells good I think. I am interested in it because of the nice scent. Please could you help me to find what species is this.

edit: and I forgot to add its fruits. I want to plant this vine, but if there are better varieties, I can plant them instead.

Sadly flowers lost their conditions because i collect them 2days ago. and i transported them in a plastic bag.


texts:
My understanding is that bipolar disorder is polygenic.

1) Does one need to have all the genes for bipolar disorder in order to have the disease?

2) Is it possible for a person to have all the genes for bipolar disorder and still not have the disease?


texts: How can (or did) Deinococcus radiodurans continue to evolve after developing resistance to mutation?

texts:
Deinococcus radiodurans has a remarkable ability to resist damage to its DNA due to radiation, dehydration or (to my knowledge) any other source. It keeps multiple copies of its genome and has a repair mechanism as well.

My question is: how could this thing evolve to be so sophisticated at preventing the processes behind evolution? It seems that a mechanism to prevent errors would also prevent changes, so that as soon as the organism got OK at preventing changes it wouldn't be able to evolve to get better at it. Were genes for these processes borrowed from other extremophiles? Is the assumption that it was in such extreme environments that the damaging influences were keeping up with the repair mechanisms? That's my guess, but I'd love to hear from others with more knowledge of evolutionary processes.


texts: How does vitamin C increase iron uptake?

texts: I've read that vitamin C increases the iron uptake in the human body. How does that work, physiologically?


texts: Is there a biological urge to have children in women?

texts:
Searching information about this subject often leads to personal stories from women making the choice to live childfree and women stating they either always wanted to have children or experienced a sudden 'baby fever'. Often this baby fever is understood to be a biological urge.

In this article a link between hormones and the need for own offspring is made a couple of times, but also contradicted.

  In  the  context  of  evolutionary adaptedness, all women were exposed
  to babies and infants, and the ‘default’ setting for the female  body
  is  to  have  experienced  both nurturing  and  pregnancies  by  the
  early  twenties. Rotkirch therefore suggests that longing for a baby
  develops out of hormonal changes evolved to prepare women for
  motherhood. These might be triggered by falling in love; the ‘nesting’
  behaviour associated with settling down; exposure to infants or the
  aging process. Conversely, however, Kravdal has found evidence in
  Norway of a demographically significant cohort for whom reproduction
  and finding a long-term partner and ‘settling’ down’ are quite
  exclusive (Kravdal 1997).

In the same article, the effects of hormones on human intercourse and attractiveness between men and women is briefly explained. However, to me it seems that the urge to have sex is something different from the urge to have babies or to become a parent. I would like to know if there are hormones or other biological changes in women that cause something like 'baby fever' or if it is rather more of a more psychological or social environment phenomenon.

Other relevant articles are often not accessible to me or prove too difficult to understand with basic biology knowledge.


texts: Why are the fertility rates of large predators kept low?

texts:
Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the fertility rate at this level? A mutation that increases fertility among the predators should quickly spread in such a population, eventually leading to an increase of the predator fertility rate followed by overpredation. But it seems that this is usually not the case. What does keep the fertility rate of predators at the level they are?

P.S: Many explanations on population dynamics cite Lotka Volterra, including the existing question on Bio.SE "What prevents predator overpopulation?". Population dynamics predict orbits for the population sizes of predator and prey. Still this does not explain why the fertility rate of predators shouldn't go up.


texts:
Are there any tools to do phylogenetic analysis of gene enrichment? This is, I have a list of genes from an experiment performed in several species, with a z-score that can be described as "enrichment" associated to each gene in each species. It's not gene expression, it's enrichment of a certain marker n the gene. I would like to compare these lists, that are not fully overlapping, across the phylogeny of the species, to see significant changes in the trend of enrichment at the gene level, or at the branch level. What tools could I use for this?

Species1 Z-score
Gene1    0.532
Gene2    0.531
...

Species2 Z-score
Gene1    0.51
Gene3    0.505
...


texts: How does the brain initiate the process of releasing the neurotransmitters?

texts:
Just reading up on the basics of neuroscience. Had a basic question on the signal generation. I understand the concepts of sodium, potassium pumps and how the action potential travels through the axon and how the calcium channel signals the release of the neurotransmitters from the vesicles. From this question I also understand what dictates the neurotransmitters released. Understanding the brain: how are neurotransmitters released in the brain?
my question  - how does this process begin at the brain? For example, how does the hypothalamus decide to to send the initial signal to the set of neurons to release norepinephrine? Is this via a similar sodium/potassium mechanism?


texts: Can the concentration of a kinase be used to identify its substrate?

texts:
I'm currently working on a dataset were I'm trying to identify substrates of an kinase in silico, I have a dataset which contains the concentrations every 0h 2h,4h,6h,8h,10h,24h for a lot of proteins found in the sample when the kinase was active. However some of these aren't targeted by the kinase but other proteins that got activated or were indirect activated by the kinase. So what I did I used R to plot the concentration of the detected proteins only if they fitted the concentration line of the kinase of interest(with a little devition allowed) this gave me the following graph:

the blue line is the kinase and the other lines are proteins found in the dataset. I know there could be postive or negative feedback which has effect on the concentation of these proteins.So my question is could the lines shown here be a possible substrate?


texts:
I'm currently an undergraduate math student and researching on the internet I discover that exists an area called "biomathematics". Looks so interesting. They use the graph theory and topology to describe the cells and DNA structure. Was love at first sight, because I really love maths and biology.

I'm reading the book "Clinically Oriented Anatomy" of Keith L. Moore and "Essential Cells Biology" of Bruce Alberts, but I don't know if I'm doing right. If anyone know how to start to learn this science I would really appreciate it.


texts: What's the difference between constitutional samples and tumor samples?

texts: I think the tumor samples have two copies of the chromosomes. But for constitutional samples, do they only have one copy of the chromosomes?


texts: Are there any scientifically based predictions or theories of future human evolution?

texts:
Reading this question of the stack exchange got me thinking. I believe human evolution is an ongoing process and will not stop. Are there any predictions/theories about the phenotypes and genotypes of humans in the future? and how they may differ in a few thousand years compared to present day?

I remember watching a youtube video and in the video the user predicts that there will be two branches of human species; a short dwarf like species and a much taller species. I'm still skeptical about this claim. Is there any evidence to back it up?

One could argue that modern medicine is preventing natural selection. How will this effect human evolution?


texts:
I'm reading a review paper. They say:

  The position of an object in head-centered coordinates (that is, relative to an animal's head) can be defined along three axes: the medio-lateral (radial) axis, the rostro-caudal (horizontal) axis and the dorso-central (vertical) axis.

I'm having a little bit of difficulty understanding this coordinate system as the paper doesn't provide a picture. Usually I would think of the three axis as an x-y-z coordinate system where the rat's head is the "origin" (from a mathematical standpoint), but the terminology here seems to be a bit different, so I'd like to understand from a biologist's point-of-view how these three axes are drawn relative from a rat's head.

Paper can be found here: http://www.nature.com/nrn/journal/v9/n8/full/nrn2411.html (bottom of page 602)


texts: Multi-nucleated cells: advantages and examples?

texts:
This question arises because I saw that monocytes and leukocytes are commonly called 'mononuclear cells' in the scientific literature. The implication of course being that other immune sub-types are multi-nuclear!

I know of granulocytes (e.g. neutrophils) that are classed as 'polymorphonuclear' because their nuclei are segmented, and can alter their shapes, and muscle cells that fuse together to form one long cell (muscle fiber) with multiple nuclei. What other examples of multi-nucleated cells are there?

I am also interested in the advantages gained by cells having multiple (or segmented) nuclei?


texts: What happens between two nodes in an evolutionary tree?

texts:
Hey guys can you help me with this one!?

What happens between two nodes (in an evolutionary tree) or a between a node and a tip?

A) at least one character changes

B) all organisms die

C) Nothing can happen between two nodes

D) Monophyly, Paraphyly, Polyphyly

E) None of the above

I came down to E) and C). Since B) doesnt even make sense, organisms don't die among two nodes- they evolve. D) it is irrelevant to the question asked A) I think that probably is wrong as well, since among a node and a tip, the organism stays the same and finally I thought C) could be the answer, but at the same time a new trait could be formed,


texts:
So I am trying to brush up on my knowledge of HATs and HDACs.

I am reading the just the 1st paragraph of the background of this study

I remember learning that HATs turn things on on, and HDACs turn things off.

It says that sodium phenylbutyrate (PB), can epigenetically regulate gene expression by inhibiting histone deacetylase.

Does this mean that one of the effects this drug can have is turning the thing that turns things off to produce the effect of turning it back on? Similar to that of a double negative?

Thanks.


texts:
Bender (2003) tested the efficacy of sonic kangaroo deterrents. Their device is static (and apparently ineffective).

Has there been any rigorous testing of the whistle-like 'kangaroo deterrent' devices fitted to the front of vehicles?


texts: Bonding in the primary structure of a protein

texts:
My textbook says:

  The amino group of an amino acid reacts with the carbonyl group of another amino acid at the end of a polypeptide chain. This condensation reaction forms a peptide bond. ... The precise sequence of amino acids in a polypeptide chain is the primary structure of the protein.

Later, it states that

  The primary structure of a protein is established by covalent bonds ...

Is the primary structure of a protein governed by covalent bonds or peptide bonds? Are peptide bonds a type of covalent bond?

Any help is greatly appreciated.


texts: What are the advantages of long read sequencing for cancer oncogenomic research?

texts:
Currently I am using whole genome nanopore sequencing, Illumina short read and 10x linked read to study oncogenesis mechanisms of certain types of rare cancer. I am wondering about the advantages of nanopore sequencing in this field, e.g. fusion gene discovery, detection of large structural variants and copy number alterations (SV/CNA), as compared to Illumina and 10x?
I am struggling with generating my doctoral thesis proposal, so any advice will be appreciated!


texts: How does collaboration on reconstructing metabolic networks work?

texts:
I am a researcher in psychology and I am trying to come up with a framework/platform in which psychological phenomena can be studied from a dynamical systems / computational perspective in collaboration with many labs. To be more concrete, the question is how to organize knowledge about psychological variables and how they are coupled by functional relationships on different time-scales that may be a function of additional variables.

My hope was to learn from disciplines that already work with a dynamical systems/computational framework for a long time. The first interesting analogy I came across were metabolic networks. I read this review about their reconstruction and while many things are different, the task is very similar to ours in that a given network of entities and functional relationships is continuously refined by the scientific community.

I saw that there are many data bases with genes, pathways, annotated graphs etc. but my main question is:

How is the scientific process of refining such a metabolic network organized? Are there platforms for this? Is there anything in place to quantify the uncertainty associated with parts of the network or to resolve disagreements? Are there any standards for implementations? Or is each group simply creating their own version based on previous literature and then publishing their new network in a paper?

I realize that this is a rather broad question and I apologize if I posted this in the wrong stackexchange forum. But I didn't know where else it would fit. I'd appreciate a lot if someone could give me some basic insights about how this field works or if someone has some pointers to relevant reading material.


texts: Biological origin of shuddering during sleep

texts:
What is the biological origin of the following behavior:

Sometimes, during the early, formative phase of sleep (when you have a gradually dimming consciousness of what all is happening around), you feel some kind of a tremor of sorts - a feeling as if you are about to fall off. The body responds by twitching the limbs, so as to "balance", and you end up waking up for a second or two, where you realize that you aren't about to fall and all is fine.

Since Cerebellum is involved with maintaining equilibrium and balance, I have the intuition that this is related to some transient behavior where the Cerebellum is dimming down. When you are in deep sleep, you do not have a sense of balance, so I guess Cerebellum does dim down the sense of equilibrium.

But the apparent flaw in my reasoning is - if this was indeed the origin, one would have experienced these tremors every time one slept. That doesn't happen, it is only occasional (AFAIK).

So, biologically, what is the true origin of this behavior?


texts: Is the innate immune system capable of identifying all foreign antigens?

texts:
I've been studying immunology on my own lately and I would like to know if the macrophages and the other components of the innate immune system are capable of identifying all foreign antigens.

As far as I understand the innate immune system is responsible for activating the adaptive immune response that will produce antibodies. So the innate immune system should be able to identify new antigens, antigens that the body has never seen before.

If that's the case, how does it work? Does everything "alive", from virus to bacteria, present the same molecular pattern that is responsible for triggering an innate immune response?

Thanks!


texts: Why is there debate about thymus being an endocrine gland?

texts:
I read on my textbook that there is debate about whether thymus is an endocrine gland. But they do have glandular cells no? Is producing T Cells the only point for thinking it not as a part of endocrine system?

So, Q: What's the reason behind this debate and has it reached any conclusion?


texts: What is the etymology of "moura" in Mourasuchus?

texts: Mourasuchus is a unique species of prehistoric crocodile so far discovered. It is a filter-feeder and has shared its habitat with Gryposuchus and the more fearsome Purussaurus in the Miocene Era --  reptilian counterpart of the Whale shark and Basking shark.


texts:
I am interested in knowing the molecular mechanism behind mechanoreception/mechanotransduction (i.e. mechanism behind receptor potential generation on mechanical stimulation). I know that most mechanoreceptors (touch, stretch, pressure etc) respond to mechanical modification of plasma membrane or of some external projection embedded in plasma membrane. I want to know the molecular basis behind this mechanical transduction.

Also, the sensory hairs in lateral line sense organs of fishes, and equilibrium and auditory sensation in animals involve generation of receptor potential when the steriocilia( or any equivalent extracellular projection), externally embedded in gelatin, bends in specific ways, another example of mechanotransduction.
(I don't know if all these receptors function with slight modification of the same basic framework or all of them operate with distinguishable mechanisms. If the latter is true, I just want one example of how molecular mechanism might bring about mechanoreception.)


texts: What nutrients can humans absorb in the mouth?

texts: For instance, I realise being able to absorb simple sugars in the mouth is pivotal in the rapid action of oral glucose gel. Thus I was wondering what nutrients in general can be absorbed directly within the mouth, and at what speed?


texts: help identifying marine item found on beach

texts:
Need help identifying this hard waxy egg like item found on beach in Destin, FL (USA).  It feels waxy and semi hard. Also smells like squid or real fishy. it is also semi transparent with dark tan looking tie on inside

Larger versions of pictures shown below:


texts: About validation process of phenological study

texts:
I have recently done a phenological study using remote sensing techniques. Now I need to validate my results and my methods, that is, to determine if the phenology estimated from remote sensing is suitable to describe phenological events or not. However, I don't have empirical phenological data from the ground to do validation.

Are there any other ways to validate the phenological signal from remote sensing, that do not require empirical data from the ground?

Thank a lot


texts:
Interstitial fluid is the fluid between cells in tissues - forming the medium between cells and capillaries. From what I gather, the typical human has 5L of blood and 11L of interstitial fluid. This raises an interesting question. If I get cut, why do I not bleed interstitial fluid?

When humans are cut, generally their capillaries open and blood comes out. But this should also allow the interstitial fluid to come out - so why don't we see it?


texts: How reactive are reduced antioxidant molecules?

texts: When antioxidant molecules stabilize free radicals, they themselves become unstable and reactive but to a lesser degree. How reactive are these reduced antioxidant molecules? And what substance stabilizes reduced antioxidants?


texts: Recommendations for a haemocytometer (phase-contrast)

texts: I'm looking for recommendations for a haemocytometer that can be used with a phase-contrast microscope. I want to use it to quantify the vegetative and spore fraction in my samples. Can I use any haemocytometer, or should the counting chamber be reduced in overall thickness?


texts: How much heme is in cooked pork and beef; why is cooked pork ("the other white meat") not red?

texts:
The new video See how Impossible Pork will make you forget about pig meat includes a very short discussion of

the addition of heme to the product to make it taste like beef
the deep red color of a heme solution
that pork is not nearly as red as beef, (after cooking it's essentially off-white)

Does pork (pig/swine muscle tissue) have substantially less heme content than beef (steer/bovine muscle tissue)? If heme is contributing to the flavor of cooked meats (rather than raw) such as pork and beef, why do they no longer have a red color after cooking?


texts: How can natural selection occur at species level whilst not occuring at the individual level?

texts:
The chapter by Douglas Futuyma in 'Evolution' (Losos et al 2013, Princeton) states that natural selection can occur at the species level. Futuyma states that if natural selection occurs at the species level it does not occur at the individual level:

  Neither gene selection nor species selection has molded the advantageous characteristics of individual organisms; rather, they have affected properties at the gene level or at the species level.

But how does natural selection occuring at the species level not affect individuals? Surely any selective advantage of a particular species must occur among particular individuals of that species. For example, if Species A is selected because it is browner than Species B, this will be because individuals of Species A are browner than individuals of Species B.


texts: Physiological reason why leaves got twisted when treated with indole acetic acid

texts:
I want to know the physiological reasons of why the leaves of my study plant got twisted when treated for 10 days with spray of indole acetic acid. I want to treat seeds with IAA, and I'm thinking about testing what will happen when I treat the leaves.

Here is a picture of what the plant looks like:

thanks


texts: Is there a database for immunoglobulin domain structure?

texts: is there a database where I can find the sequences of the hypervariable domain of immunoglobulins and the sequences of the related antigens? Thank you


texts: Is the number of legs in myriapoda determined entirely by the genome?

texts:
Myriapoda (comprising, among others, millipedes and centipedes) can have hundreds of legs (Illacme plenipes having up to 750 legs). Interestingly, the number of legs (or leg pairs) appears to differ not only between myriapod species, but even between individuals of the same species:

  Body light cream-colored, thread-like, extremely narrow and long (max. width: ♂ 0.55, ♀ 0.64; max. length: ♂ 28.16, ♀ 40.40). Adult individuals with 84 – 192 segments, and with 318 – 750 legs (VMNH paratype ♀ with 192 segments and 750 legs, more than any other organism known on Earth).

  Source: "A redescription of the leggiest animal, the millipede Illacme plenipes, with notes on its natural history and biogeography"

This raises the question: Is the number of legs in myriapoda determined entirely by the genome, or do environmental factors play a role in precisely how many legs eventually develop?

Note: Myriapoda generelly hatch with very few legs, and more legs develop during successive moults. Some examples can be found here.


texts: can somebody please Identify this queen ant?

texts: hi, i found this queen in France and i want to know if it is a species i can take back home to England. i cant identify her since the only queens I've ever kept are Lasius Niger so i would like some help please!!


texts: Why is it better to drink room temperature water instead of cold water?

texts: My teacher told me that drinking water that is room temperature is better for you then drinking cold water, but she did not tell me why that is. I want to know because I often drink cold water (with ice), because I can't stand water that is room temperature or warm.


texts: What is "contigs" in Picard's ReorderSAM?

texts:
I've used BWA to map my NGS reads against the hg38 genome, and I have a BAM file. I'm not doing genome assembly, and my reference genome file has the human chromosomes. Thus, I shouldn't have "contigs". But...

  https://broadinstitute.github.io/picard/command-line-overview.html#ReorderSam

and quote:

  ReorderSam reorders reads in a SAM/BAM file to match the contig ordering in a provided reference file, as determined by exact name matching of contigs

Q: What does contig ordering mean, for my whole-genome-sequencing experiment? In particular, what does matching the contig against a reference file mean?