2
votes
2answers
258 views

What mechanism suppresses melatonin release in humans?

I'm looking at melanopsin, a photo pigment in the human eye. One of its actions is to trigger suprachiasmatic nuclei SCN to suppress melatonin release. I'm interested in learning what is the exact ...
14
votes
1answer
540 views

Why is yawning contagious?

Why does yawning seems to be contagious? Is this similar to laughter being contagious or does it has a different reason?
4
votes
1answer
507 views

How do I view the simulated protein structure along with ligand in VMD?

I did a simulation of a protein-ligand complex, and it has stabilized after 5 ns. I have got the respective pdb files for every ns, but when I try to view in VMD (Visual Molecular Dynamics), I cannot ...
4
votes
3answers
144 views

Results of a complete DNA sequencing - are they 100% reusable?

Is that correct that a complete DNA sequencing (the whole genome) need only to be done once (per person)? After that is done, it the complete genome can be stored and once the new genes (and their ...
2
votes
0answers
65 views

Why do animals sleep [duplicate]

Animals spend a good portion of every day doing nothing, and it seems like that time could be better spent hunting, searching for mates, etc. Also, animals are not aware during sleep, so it would be ...
3
votes
1answer
721 views

How does sugar enter neurons if they don't use insulin?

I heard somewhere that as opposed to other cells, neurons do not use insulin to get their sugar supply. Why is that? What is the alternative mechanism? I assume sugar can't just enter the cell ...
2
votes
1answer
124 views

How long does a tan last?

How long do melanocytes and melanosomes continue to protect DNA after UV exposure? Basically, if skin is tanned, then over the next month it is shed, will melanocytes continue to produce high levels ...
2
votes
0answers
44 views

Can Infant Crocodiles digest Bread?

I'm just curious as to whether crocodiles and if you require specifics, saltwater crocodiles, could eat bread as infants. I was watching Lake Placid and I was curious as to whether infant saltwater ...
1
vote
0answers
110 views

How does geography affect morphological features of the human body

I've seen many times how a person born in one place, goes to another country for a long time, and then they start looking more like the people there, but I never found out how it works. This report ...
2
votes
2answers
274 views

How to know if a woman is fertile without actually making her pregnant?

How to know if a human female is fertile (can give birth to child in future) without making her pregnant? Any signs, tests?
5
votes
2answers
2k views

What is the function of nodes of Ranvier in axons?

In a neuroscience class I'm taking, it was explained that myelin covers axons in sections, the uncovered sections are called nodes of Ranvier, and signals propagate much faster in the covered ...
3
votes
3answers
2k views

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

My apologies if my question is too basic, and please point me to a more appropriate forum. I am reading the textbook "Essential Cell Biology" by Alberts et al, and am consulting other sources as ...
2
votes
1answer
174 views

Two brown-haired people have two children, P and Q. P has blond hair. Q has brown hair. What is the probability that Q is heterozygous?

Two brown-haired people have two children, P and Q. P has blond hair. We therefore believe that each parent is heterozygous and that blond hair is a recessive trait. Q has brown hair. What is the ...
1
vote
0answers
25 views

What are the conditions that must be satisfied in order for drugs to be deliverable via the epidural route?

I ask this because I've read that while pentazocine is approved by the FDA for the treatment of labour pain, epidural administration is not listed as one of its means of administration (which thing I ...
9
votes
1answer
175 views

How are new people created from the DNA of an aged person. i.e. Why are we young?

The question "why do we age" has been asked numerous times. But why are we young? The cells of the adult human being are an age (time>0), but how can old cells create new cells that are younger than ...
2
votes
1answer
242 views

Copper for cell incubator to prevent contamination

For some reason the lab seems to have a problem with contamination every so often. It's virtually impossible to prevent bacteria, viruses, fungi, etc. from getting into the incubator every time you ...
1
vote
2answers
331 views

PEG-silane treatment: why incubate for 18 hours at 60 degrees Celsius?

I am conducting a biochemistry-related experiment and I have been unable to understand a step which is commonly performed. My aim in this step is to apply a PEG (Polyethylene glycol) silane layer. ...
3
votes
1answer
254 views

What factors govern the variable age of onset in Huntington's Disease?

"Huntington's disease (HD) is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems." As we all know, this genetic disease ...
3
votes
1answer
403 views

How is Hypertonic Urine Produced in a Mammalian Kidney?

I know that the ascending loop of Henle is impermeable to water and ions, and, by end of the ascending limb, the osmolarity of the tubular fluid is very low due to the active transport of ions out ...
3
votes
0answers
51 views

What are polytene bands, and why are they there?

Drosophila polytene chromosomes have been particularly useful in genetic research, as it made cytogenetic gene mapping possible with very little effort. This was primarily accomplished due to polytene ...
1
vote
2answers
155 views

What gives observable light its colors? [duplicate]

I know that difference between different colors of light is difference between their wave length but I don't know what gives beautiful colors (like rainbow colors) to different wave length of ...
2
votes
2answers
273 views

What's a good and reliable database on the pharmacodynamic and pharmacokinetic data of drugs both approved and unapproved?

What's a good and reliable database for the pharmacodynamic and pharmacokinetic data of drugs both approved (in the US and elsewhere) and unapproved?
2
votes
3answers
651 views

Michaelis-Menten Kinetics: Does measuring apparent Km and Vmax take into account competing reactions?

I am learning about why it is important to measure Km and Vmax for each experimental setup because measuring the "apparent" Km and Vmax includes enzyme inhibitions of which one might not be aware. ...
3
votes
1answer
213 views

Macroevolution vs. microevolution

Where is the line usually drawn between macroevolution and microevolution? I thought that, although similar processes govern both, the line was at the species level, with macroevolution being changes ...
2
votes
1answer
37 views

What is a good review book/source for microbiological diagnosis?

I am trying to find the diagnosis figure for different bacteria where phases are illustrated. I am using at the moment: 1) First Aid for the USMLE Step 1 2013 and 2) Medical Microbiology by Murray et ...
1
vote
0answers
41 views

What's the mechanism of action of Levomepromazine's analgesic effects?

I have absolutely no idea as to how Levomepromazine elicits its analgesic effects so please do direct me to journal articles and other credible sources with you, the answerer, making a summary of ...
2
votes
1answer
355 views

Can animals use the nitrogen in chitin to build proteins?

Fungi and insects contain chitin, which is about 6% nitrogen. Can an animal - like me - make use of this as a nitrogen source to build proteins? Are there any animals that can do this? Are there ...
1
vote
1answer
89 views

Confusion related to the use of PCA to determine the background network

I was reading this paper related to use of gene expressions for predicting the drug response. I have this confusion, the paper has used PCA on the covariance matrix formed by the genes to get what is ...
0
votes
0answers
68 views

Which receptor in particular does, “MUSCARINIC CHOLINERGIC” refer to in Goodman and Gilman? [on hold]

On pg. 410 of Goodman and Gilman's The Pharmacological Basis of Therapeutics 12th Edition the term "MUSCARINIC CHOLINERGIC" is used (in the context of side effects of antidepressant agents) with ...
35
votes
3answers
2k views

Why are there no wheeled animals?

In physics, "almost everything is already discovered, and all that remains is to fill a few unimportant holes." (See Jolly.) Therefore, on Physics SE, people are veering off into different directions: ...
1
vote
1answer
115 views

Lineage selection in plasmid evolution

I've been reading through Paulsson (2002) and I am not sure what he means by "lineage selection" in the second to last section. The paper deals with plasmid replication, and mostly concentrates on the ...
2
votes
0answers
197 views

Software for counting fly eggs

Is there any software that could be used to rapidly (quicker than humans) count the eggs laid by Drosophila on a substrate by placing them under a microscope with a camera attached? The eggs are laid ...
2
votes
2answers
214 views

What type of photosynthesis is performed by phytoplankton?

I am not a biologist, but I know there exist three variants of photosynthesis, namely C3, C4 and CAM. I would like to know what type is used by the ocean's phytoplankton? It might also be that ...
9
votes
1answer
283 views

Structure of fitness landscapes in the NK model

The NK model of rugged fitness landscapes consists of $N$ sites where fitness contribution of each site depends on its state $\{0,1\}$ and is epistatically affected by $K$ other sites. When defining ...
5
votes
3answers
294 views

Tool for nucleotide alignment with all nucleotide codes (e.g. R, Y, W, S, etc.)?

I have a vector sequence and would like to find the following nucleotide sequence in it. AASYWSRA This query sequence uses several degenerate symbols, defined ...
2
votes
2answers
364 views

What would it take to recognize a deer by its photo?

I am trying to recognize a deer by its antlers or any other means. Elaborating: I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so ...
1
vote
0answers
22 views

Do the antlers re-grow in the same pattern every year? [duplicate]

I am a software engineer and I am trying to develop a system to identify a deer by its photograph. Most deers lose their antlers every year. I would like to know if they re-grow in the same pattern ...
2
votes
0answers
30 views

How is the appropriately-stratified gut microbiome acquired in organisms performing horizontal transmission?

I am studying horizontal transmission of primary symbionts in insect reproduction. This reminded me of an earlier question I had asked, in which I learned that humans analogously acquired their ...
2
votes
1answer
69 views

Whence fecal E. coli (et al.) if swallowing it is dangerous?

I don't know much about medicine, and I know even less about microbiology, but I understand that there are organisms in the lower gastrointestinal tract (and in feces) of a human, like Escherichia ...
1
vote
0answers
63 views

Carrying or packaging capacity of SAD B19 dG rabies virus

I'm wondering about the carrying capacity also referred to packaging capacity or loading capacity (how many base pairs can be packed efficiently into virions) of the pseudotyped rabies virus SAD-dG as ...
2
votes
0answers
95 views

How long does Lentivirus take to express in vivo mouse neurons?

Does anyone know how long it takes for a standard Lentivirus vector to express its genes (under a strong promoter such as CAG, CB7, etc.), after injection into the brain of a mouse? By hearsay I ...
2
votes
2answers
133 views

How does your body know when it is infected so it can invoke a fever?

How does your body know when it is infected with a virus or bacteria so it can invoke a fever or ramp up the immune system?
8
votes
2answers
237 views

What is the smallest molecule that can present as an antigen to the immune system in the context of allergies?

People often claim, in a colloquial sense, that they are "allergic to everything". Is it possible to have a full-fledged IgE mediated allergic response to very small molecules? I was always under ...
3
votes
1answer
159 views

What molecular processes are involved in pseudopodial extension?

I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
3
votes
1answer
186 views

Are there natural selection experiments that quantitatively agree with theoretical modeling?

Has anyone ever conducted an evolution experiment and quantitatively compared it to theory? For example, has anyone ever put bacteria in a million petri dishes filled with antibiotics and calculated ...
6
votes
2answers
212 views

Is local equilibrium a reasonable assumption for evolutionary processes?

Whenever I look at discussions of fitness landscapes (in particular, Kauffman's NK model) the questions tend to resemble: The population is at a local equilibrium, but another equilibrium of ...
-4
votes
1answer
101 views

Were any brain fusion experiments ever conducted? [closed]

Did anybody ever conduct experiments on fusing living brains?
0
votes
1answer
117 views

How to classify equilibrium points [closed]

I have the two differential equations: $$\frac{dN_1}{dt} = N_1(2 - N_1 - 2N_2)$$ $$\frac{dN_2}{dt} = N_2(3 - N_2 - 3N_1).$$ I worked out the equilibrium points to be at $N_1 = 0, \frac{4}{5}$ and ...
6
votes
2answers
149 views

Would muscle fatigue still occur if aerobic conditions for a working muscle is maintained?

Put another way if the muscle is given everything it needs to contract and do work will it ever get tired or have a reduction in energy efficiency? As far as I understand muscles depend upon a ...
1
vote
0answers
147 views

How does Tianeptine work to elicit its therapeutic effects?

Tianeptine is an antidepressant and anxiolytic that has some additional analgesic properties that's used in some European countries, and the theories I've heard about how it works include the ...

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