13
votes
0answers
232 views

What is the percentage of people living in England in 1500 AD whose lineage is still alive?

This sounds a bit random but it stems from a lecture in statistical genetics which I attended a while ago. We were shown a population lineage graph from which it was clear that most lineages go ...
12
votes
0answers
119 views

What have the L-systems (Lindenmayer systems) been actually used for in biology?

Wikipedia: An L-system or Lindenmayer system is a parallel rewriting system and a type of formal grammar. L-systems were introduced and developed in 1968 by Aristid Lindenmayer, a Hungarian ...
10
votes
0answers
465 views

Why don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
9
votes
0answers
101 views

Standard practice for generating rarefaction curves from Next Generation Sequencing data

We have a few million 18S reads from a particular environment. The reads have been clustered into Operational Taxonomic Unit (OTU), and the OTUs annotated against a reference database. To generate a ...
9
votes
0answers
122 views

Selection for less efficient egg transfer in Human Botfly life cycle

I have heard that the Human Botfly transfers its eggs through other invertebrates [1], and it strikes my curiosity that if an insect could simply land on its host directly to deposit its eggs, then ...
9
votes
0answers
162 views

At which step apply a detection filter when preprocessing microarray data? (Before/After normalization, batch effects removal)

I am trying to understand what is the best practice when preprocessing microarray data using a detection filter (on scanner p-value). Suppose I have a microarray dataset that I have to normalize with ...
8
votes
0answers
282 views

Contact Inhibition of Cell Division: Signaling Pathway

The following article refers to contact inhibition of cell division in epithelial cells, specifically MDCK cells: Collective and single cell behavior in epithelial contact inhibition. In their review ...
8
votes
0answers
562 views

Evolutionary reasons why you cannot tickle yourself but masturbate

There are obviously good reasons that explain why you cannot tickle yourself (see e.g. here). This got me thinking why it is possible to masturbate... Wouldn't it make more sense to not being able to ...
8
votes
0answers
100 views

How to define “Quasifixation” in continuous approximation of finite population?

Background Many models including the famous very first models derived by Sir Ronald Fisher in his early career, assume infinite population size. In an infinite population, an allele can rise in ...
7
votes
0answers
79 views

What causes the range of severity of neurological deficits in Down's syndrome?

It's known that the severity of symptoms caused by a trisomy 21 varies from individual to individual. Part of the explanation for this range of severity is the finding that 94% of Down's syndrome ...
7
votes
0answers
109 views

What is basis of multifunctionality of “master glands” in the endocrine system?

I have just started reading about the endocrine system and I am having some difficulty understanding the basis of distribution of glands and associated hormones. I am using multifuntionality to ...
7
votes
0answers
239 views

What bacteria shed harvestable energy from root zone organic matter?

I recently heard of a successful effort that harvests energy from soil at plants' bases due to apparently bacterial breakdown of wastes from the plants: Via photosynthesis a plant produces organic ...
6
votes
0answers
106 views

Is there an evolutionary basis for why women mature faster than men?

Females develop both physically and mentally earlier than males do. For example; females start puberty at an earlier age than males, and females brains mature more quickly than male brains. Girls ...
6
votes
0answers
63 views

Variance in Fst in the infinite island model

The most famous result in the study of structured populations come from Sewall Wright. He showed that in an island model, where each subpopulation is of size $N$ and the migration rate is $m$, then ...
6
votes
0answers
220 views

Is there a karyotype database for human cell lines?

I'm looking for the karyotype of a specific cell line. Some karyotype are well known, such as HeLa or some carcinomas, but some are very hard to find, such as LG2 (B cells). Is there a database ...
6
votes
0answers
75 views

Identity by descent among unrelated individuals

I was reading a couple of papers which talk about IBD (Identity by descent) among unrelated individuals (for eg. http://www.pnas.org/content/109/4/1193.long). However they do not seem to clearly ...
6
votes
0answers
73 views

How to measure Na/K channel activation at the membrane level?

Assume that there are two different signals occurring on the ECG - during depolarization and repolarization in the standard ECG. I was advised not to use the standard ECG in measuring the exact ...
6
votes
0answers
54 views

Effect of Aging on SA node's sympathetic fibers

I am trying to understand the effect of aging on the sympathetic fibers of SA node. I know that aging shifts the vagal curve to left in frequency due to aging. However, I am interested if aging has ...
6
votes
0answers
73 views

Does preservation in ethanol alter leaf litter mass?

I have benthic samples that were collected with an Ekman dredge from some small ponds. The samples contain quite a bit of coarse particulate organic matter (CPOM, basically dead leaves). I would ...
6
votes
0answers
134 views

Comparative cost of RNA-seq vs sequencing full length cDNAs

I am in the process of assembling and annotating the genome of a non-model organism, using almost exclusively short read (paired-end Illumina) data. Throughput is one obvious benefit of these data ...
5
votes
0answers
33 views

How to estimate heritability from breeding data

I have a lot of plant-breeding data (tens of thousands of results) that are composed of phenotypes of parents and offspring. The plants however went trough years of selection and it is not balanced. ...
5
votes
0answers
27 views

Why do emperor penguins breed during the antarctic winter

No land animal, and I think no sea animals either, stay in the antarctic during winter - except for one: The emperor penguin, which does not only stay there, but its prolonged stay involves 4 months ...
5
votes
0answers
46 views

Why do viruses last longer on hard surfaces than porous ones

All the papers I've read about survival of viruses outside of the host refer to longer survival times on hard surfaces without explaination. As a layman I would have thought that a virus (who's main ...
5
votes
0answers
33 views

Why do Arctic predators accumulate vitamin A?

Top predators in the Arctic are known to accumulate vitamin A, often to levels that are toxic for human consumption. A 2012 study by Senoo, Imai, et al. found that the livers of several predator ...
5
votes
0answers
50 views

Are high sounds worse for your hearing than low sounds?

From about 80 dB it is possible to suffer loss hearing after a couple of hours. But does it make a difference what frequencies those sound waves are or is it just the volume of the sound in dB that ...
5
votes
0answers
102 views

What will happen when humans are injected with plant growth hormones

Will plant growth hormones (PGHs), (let us consider auxins for example) poison our body or not? I do realise that when you eat a shoot, auxins get digested and are less likely to be poisonous but when ...
5
votes
0answers
40 views

How much of the genetic differences between humans and chimpanzees are due to genetic drift?

Both natural selection and genetic drift play a part in changing our DNA over time. Are there trustworthy estimates how much of the differences over the whole genome between us and chimpanzees are due ...
5
votes
0answers
46 views

How can microarrays be used to quantitatively determine level of gene expression?

This is probably a stupid question because I don't fully understand how microarray experiments work. I'm trying to understand how microarrays work but I'm confused about something which I can't seem ...
5
votes
0answers
51 views

What is the reason for fear induced defecation?

I started to handle mice for my job and noticed that they tend to defecate and/or urinate when they are scared. The fear is induced by me, because I need a long time (due to inexperience) to grab the ...
5
votes
0answers
97 views

Why do mammals produce more carbon dioxide than insects?

I understand that mammals produce more carbon dioxide than insects on a gram per gram basis, but why is that? I'm thinking it might be because mammals are warm-blooded, which require more energy ...
5
votes
0answers
54 views

Do “scars” in humans replace all the skin layers or only some layers?

When someone has a cut or surgical incision that results in a "scar", is the scar tissue replacing all 3 layers of the skin (epidermis, dermis, hypodermis)? Or only the first one or two of them?
5
votes
0answers
23 views

Why sympathetic and parasympathetic nerves originate in different parts of CNS?

Curious if there is a reason for having: parasympathetic nerves originating from brain stem and pelvic part of spinal cord sympathetic nerves originating from thoracic and lumbar parts It looks ...
5
votes
0answers
49 views

Is high metabolism linked to high evolutionary turnover?

I recently read The Dinosaur Heresies by Robert T. Bakker, a 1986 popular science book presenting arguments for an active lifestyle and high metabolic rate in dinosaurs. One of the arguments that ...
5
votes
0answers
176 views

What traits make mountain goats so well adapted to mountain living?

I've never really understood how mountain goats manage to survive so well in mountainous regions. I've seen them scale almost sheer cliff faces with apparent ease, and they can almost sprint ...
5
votes
0answers
29 views

Can we predict a person's tolerance to cold exposure during excercise?

Being an amateur athlete and student of anatomy I've always wanted to know if there is a formula for determining an unconditioned body's tolerance to cold temperatures while exercising. I know the ...
5
votes
0answers
37 views

What type of tree is this?

I photographed this group of trees a couple of years ago at the northern tip of Prudence Island in Narragansett Bay. Any idea what species these are?
5
votes
0answers
221 views

What are the branches of system ecology?

What are the branches of system ecology that scientists research in nowadays? Or what can system ecology can applied to, or be used? I have read its Wikipedia page, but sadly it doesn't answer my ...
5
votes
0answers
72 views

How does a garlic clove thrive inside a closed refrigerator?

A garlic clove has been growing very well inside a closed refrigerator. It has developed beautiful green stalks, which I think are the equivalent of leafs. Since they are green, I assume they ...
5
votes
0answers
46 views

Two different Leucochloridium infected snails - different species?

In the last three days, I have found two snails infected by some species of Leucochloridium. I found them in my garden in the south-west of Sweden. Now I'm wondering if they are the same species or ...
5
votes
0answers
78 views

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

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 ...
5
votes
0answers
77 views

Understanding F-statistics in population genetics

I am reading a classical Weir and Cockerham 1984 paper about Fst estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within individuals ...
5
votes
0answers
47 views

Is it possible that the vapour form of propylene glycol could lower a humans blood oxygen saturation by the manner in which N2O does?

My understanding is that by inhaling nitrous oxide leads to the body not being able to take in as much oxygen as it usually would. Is it possible that a heavier soluble gas such as the vapour form of ...
5
votes
0answers
105 views

Phylogenetic method to detect shift in mean of continuous variable

I am currently working on a project where I study the change of a continuous morphological variable with body size (measured as body weight) across diverse taxa (insects, spiders, lizards, frogs). In ...
5
votes
0answers
106 views

Where can I get numerical data for the PAR (photosynthetically active radiation) curve?

I'm trying to do some rough figuring to calculating efficiencies of various light sources for growing plants. I'm hampered, however, by the lack of a curve to multiply by the spectrum of light ...
5
votes
0answers
370 views

Genetic expression in interspecific hybrids

Referring to interspecific hybrids, I have the following two questions:- Quoting from wikipedia:- The offspring of an interspecific cross are very often sterile; thus, hybrid sterility ...
5
votes
0answers
87 views

effect of background selection on promoter regions compared to distant enhancers?

Has anyone looked at the effect of background selection on the levels of conservation of promoter regions compared to distant enhancers? Do promoter regions have a higher conservation due to ...
4
votes
0answers
40 views

How do chromosome pairs get “paired up” for protein synthesis?

If my understanding is correct, during interphase a normal human cell will have 46 chromosomes scattered about in the cell nucleus. These chromosomes can be thought of as pairs: there are two copies ...
4
votes
0answers
29 views

How much do urban pigeons move around cities?

Do they tend to live their lives in one area of the city or do they move around? For example, do pigeons born on London's Trafalgar Square live their whole lives centered around Trafalgar Square or ...
4
votes
0answers
68 views

Does Cas9 require a nuclear localization signal (NLS) for it to work in a Eukaryote?

I'm trying to establish if it's required to add a NLS to Cas9 when expressed (or transfected) in a Eukaryotic cell. Several papers report using a viral NLS, but is it absolutely necessary? Could ...
4
votes
0answers
39 views

Does depolymerisation take place at the minus end of microtubule?

Wikipedia says that Dynamic instability refers to the coexistence of assembly and disassembly at the 'ends' of a microtubule. but Karp's Cell Biology, 7th edition says Dynamic instability ...

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