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seen Dec 9 '13 at 14:45

Dec
5
comment Are Asians more genetically homogenous than other races?
@SonnyOrdell I am, probably later today. My local time is GMT. I think we may do it there: chat.stackexchange.com/rooms/11814/genetic-variation-in-humans
Dec
5
comment RT-qPCR of selected differential expressed genes: which dilutions in calibration curve?
I am not sure what you're trying to do. I think you want to measure gene expression level (amount of transcript), but then why would you use DNA as your reference? What do you want to calibrate with the DNA?
Nov
20
comment Are Asians more genetically homogenous than other races?
Fine with chat - but I don't know how, I've never used it :-) Give me some time to find relevant papers and we can talk.
Nov
20
comment Are Asians more genetically homogenous than other races?
@SonnyOrdell No. I agree that when people say Asians or Black, we generally know what they mean - because we tend to think in general features of appearance. This may be particularly true in the US, where the people of many greatly different ancestries live together (imagine picking only "full" colours from the rainbow). But the gradients are there - in physical appearence and in DNA. And "what people look alike" is just adaptation to the environment (ie skin color is an adaptation to uv radiation). Anwyay, this comment section is probably not a best place for a complex discussion...
Nov
20
comment Why is there such an argument about evolution?
AlleleA1 is a great population genetic software that really gives you a good idea how the frequency of alleles is affected by various factors. You don't have to know R to run it, but you need a Mac (a double bonus :-)
Nov
20
comment Why is there such an argument about evolution?
@GriffinEvo Yes, you're right for the majority of mutations (some obvious ones excluding, like stop mutations in housekeeping genes). We must have an idea of a genetic basis of a certain phenotype to be able to speculate about effects of potential mutations underlying the phenotype. But the ability of induction of mutation in a defined genomic position allows us to verify/narrow down these speculations in a really clean and clear experimental way.
Nov
20
comment Are Asians more genetically homogenous than other races?
Answering the second part of the question: I mean people of Australian or American ancestry. The first part: I encourage you to read that Barbujani paper. When people say "race" they tend to mean a social construct that classifies people into groups based on physical appearance (skin color, hair, eyes etc.). You cannot divide people like that based on the DNA, because the variation is continuous and all division of it will be arbitrary. It's like seeing a rainbow: can you tell me exactly where the yellow ends and orange begins?
Nov
20
comment Why is there such an argument about evolution?
@GriffinEvo Yes. We can introduce a specific mutation (substitution, insertion or deletion of a single base pair up to large chunks of DNA) into a specific position in the genome. In many cases, we know a good deal how if affects the phenotype. In other cases, we have no idea but this is exactly the reason it's done.
Nov
20
comment Why is there such an argument about evolution?
@terdon Yes, in this case this is simply out of realm of science.
Nov
20
comment DNA and gene activation
Humans have about 20000 genes. But see also this http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2898077/:
Nov
20
comment Why is there such an argument about evolution?
Heh, this is way OT so we should not go much longer, but I then ask: what is your argument for the premise (god(s) exist) in the first place?
Nov
20
comment Why is there such an argument about evolution?
But you can of course argue against the existence of god on the basis that in many religions there are beliefs in acts of god(s) or features of god(s) that are in opposition to scientific knowledge (walking on water, wine from water etc.). By asserting a level of probability on things that people say god does you can indirectly assert the likelihood of god existing in the first place. So because nothing god does / what god is is physically possible as far as science can tell, very likely there is no god at all.
Nov
20
comment Why is there such an argument about evolution?
@GriffinEvo >if we artificially induce mutations, we can not direct what the mutation does to the phenotype. I don't think you meant that. Yes we can direct what the mutation does to the phenotype - we routinely do it in organims we can genetically manipulate (bacteria, yeast, mice etc.) and of course only in cases where we understand the relationship between genotype and phenotype. Better way of putting it would be that in most cases in natural populations we cannot predict consequences of a given mutation, as there are many factors in nature that can influence the fate of that mutation.
Feb
15
comment How is evolution possible in contemporary humans?
I just want to emphasise that "races" is more of a social construct than a scientifically strictly defined category (see Razib Khan's comment here: blogs.discovermagazine.com/crux/?p=1350#.UR45L1qcYVo) . So while I agree with a term "alleles associated with some populations" the other terms you use ("race has a genetic component", "less white") are more murky (unless, in the latter example, you're talking about alleles associated with skin color - but then again, they do not necessarily correlate with ancestry).
Nov
16
comment By What Mechanism can Felines Reverse Diabetes?
I've just had a look at en.wikipedia.org/wiki/Diabetes_in_cats#Insulin_injections and I am not sure what more would you want. Although I do think that Wiki is wrong in saying that diabetic remission in T2 is unique to cats. Temporary remission happens even in T1 humans, and in T2 humans as well.
Nov
16
comment By What Mechanism can Felines Reverse Diabetes?
Could you please provide any source of this information? And are you talking about type 1 or type 2 diabetes? Because I am pretty sure once you develop T1 you cannot get back, at least if you're a mammal.
Nov
12
comment How is evolution possible in contemporary humans?
Can I just add here that evolution would happen even without any directional selective pressure? You're all talking about fitness and directional selection, whereas selectively neutral processes (drift, migration) can also dramatically change the allele frequencies in a population ergo evolve the populations (think asteroid and the dinosaurs).
Apr
18
comment What are the limitations to current nucleotide sequencing technologies?
@Daniel Yes, you're right in principle. But then if what you require is as-perfect and complete a sequence as possible, then I'd propose that the limitations are the same as they were before: DNA itself, with it's super high repetitive content, poliploidy. Sanger and positional cloning did not manage to solve this problem (hence gaps in finished human genome sequence) and they're regarded as the golden standard (am I that old already?).
Apr
18
comment What are the limitations to current nucleotide sequencing technologies?
All or most of the limitations you describe can be simply overcome by brute force method. Almost any genome sequenced on any high throughput technology today will be of very high quality if you sequence it 100 times. It's just a matter of time and money. Remember the original human genome was sequenced by many Sanger machines and a lot of cloning.
Apr
18
comment What exactly are computers used for in DNA sequencing?
It's not the sequencing itself that is computationally particularly intensive, but the assembly of the sequenced fragments into continuous DNA. Also, even a computationally trivial task will take time if repeated billions and billions of times. To get any decent quality sequence, one has to sequence the DNA multiple times (20+). If you have a genome that's 3 billion bases long...