Agreed - if I had to identify one paper in the last 60 years that has revolutionised biology it would be Watson and Crick's paper in Nature in 1953; which ends with possibly the most prescient sentence ever in a scientific paper! See URL below
Posts by David Wynick
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Like you I can find no mention of this other than a few alien abduction type websites, spawned presumably by H1N1 last year. I think we can safely assume there is no evidence for this unless of course it a global conspiracy to hide the truth from us all (which as we all know is "out there").
3rd Sep 2010 13:07:56
Re: melanism (posted in Mammals)
This question has been answered before - see link below
you will need to take a picture and then upload it to the site.
2nd Sep 2010 16:16:48
Re: Growth of a Dolphin (posted in Mammals)
As with Dave's response to your other post on the speed whales swim, I am not sure this is a question that there is a meaningful answer to - there are too many unknown variables!
1st Sep 2010 19:12:42
Re: Biologist (posted in General Biology)
This sounds suspiciously like a home/course work question which we do not answer. If I am mistaken please do post again.
Agreed with all of the above and I too am extremely sceptical about the "friendly bacteria" claims in many probiotic yoghurts and foods. The ONLY time I know when live bacteria really do help is when one has taken an antibiotic which has destroyed much of our normal gut flora resulting in severe diarrhoea. In that instance eating live yoghurt corrects the problem with in 2-3 days but even then I am not sure the "probiotic bit" adds much to any ordinary live yoghurt.
An allele is a different (mutated) form of a gene. In the example you give hundreds of mutations are known in the PAH gene many of which will code for a different version of the protein.Each mutation is known as an allele which is then inherited by standard Mendelian genetics.
This and similar questions have been answered before - please browse the answers in the Research and Careers forum.
I am sorry Emilio but it would seem that no one knows the answers to your questions.
29th Aug 2010 14:00:06
Re: Type 2 Diabetes & cannabis - Can it help? (posted in Human Biology and Evolution)
The simple answer to your question for type 2 diabetes is mostly likely not. As Steve says Rimonabant has been withdrawn (its principal mechanism of action was appetite suppression) and other cannabinoid antagonists have thus far (in small clinical studies) been largely ineffective for diabetes control.
Similarly, again disapointingly, cannabinoids have been far less effective for the treatment of neuropathic (chronic) pain that the anecdotal reports from marijuana smokers would have implied.
None that I know of! Prion protein does not really meet your definition though is transmissible with out DNA/RNA.
Those of us that are medics and scientists do it for the love of both and not for money either! It takes 5-6 years to qualify as a medic and then another 10+ years before you are sufficiently experienced and qualified to be a GP or a consultant. During that time you work very long hours often at night and weekends. The pay is better that a post-doc but rarely gets above 50K even with out of hours working till one gets to be a consultant/GP (ie 15years after leaving school). Starting salary as consultant is about 70K so yes it is reasonable pay but I think most medics and society would argue we are worth it - we make life and death decisions daily and boy do we "pay" if we screw up - morally and financially. Burn out is very common amongst medics - we have a high drop out rate and one of the highest suicide rates in the country.
On top of all of the above being a medic and scientist (clinical academic) is even harder work - training is as above and then on top we have to do a PhD followed by a post-doc. We do no private practise, work even longer hours, and try and juggle medicine, research and teaching undergraduate medics. It's not for the faint hearted and for sure no one ever went into my job just for the money! In addition and unsurprisingly the numbers of clinical academics is shrinking rapidly which augurs very badly for the next generation of medics.
22nd Aug 2010 11:52:56
Re: Healing a dead zone, ecologically (posted in Ecology, Biodiversity and Behaviour)
Sorry Mark but it would seem no-one knows the answer to your question.
22nd Aug 2010 11:45:41
Re: Identification (posted in Fossils)
It looks like a cervical vertebra - what species it comes from I have no idea - maybe someone else can help.
The link below lists the many salts and proteins in human sweat. If one evaporates sweat (on teflon or anything else) then the contents will leave a residue such as you describe.
Apologies for not answering your question fully enough. Fascinating paper and your reading of it is spot on! To summarise in cats:-
1. Inactivating mutations in MC1-R are not the cause of tortoiseshell.
2. The O-locus which causes tortoiseshell is on the X-chromosome which the MC1-R is not
3. The exact location and function of the O-locus is unknown
4. How the O-locus inturn interacts with white-spotting locus is also unknown
In summary, there is an awful lot more we don't know about cat coat colour as compared to what we do know!
7th Aug 2010 06:57:54
Re: identifying a flying insect and whether its notifyable (posted in Invertebrates (Including Insects))
sharon then posted more info
In addition to the previous information about the 'fly' it has six legs (with heart shaped feet) and two wings (to the end of his body) from the upper big part of its body. I caught it when it was flying around the bedroom light. it buzzes, more so now its trapped. it cleans itself like a fly. we're in the north east london town.. I have lots of shrubs in my garden. its body looking from the top looks like a wasp with black and grey stripes though the grey stripes don't quite meet in the middle but the tip of its tail from the side view tips downwards.
7th Aug 2010 06:56:41
Re: identifying a flying insect and whether its notifyable (posted in Invertebrates (Including Insects))
I am sorry but the pictures above are so out of focus it is difficult to make any comment. Please take more - check they are clear and in focus and then upload them.
It is actually even more complicated than you describe above. The wiki pages below give a reasonable summary of our current understanding. As you will see there are multiple genes at play, X-inactivation that affects some cells and environmental factors!
http://en.wikipedia.org/wiki/Tortoiseshell_cat#Genetics
This question has been asked before - if you search the fora for "titanium plate" you should find the answer to your question.
2nd Aug 2010 17:00:21
Re: Identifying a flying insect, hopefully (posted in Invertebrates (Including Insects))
How does an insect fly hopefully?
The incidence of short and long sightedness in children and adults is increasing. That is partly due to screening and better diagnosis and in part due (it is thought) to children reading and watching TV earlier in life - I stress the last part of that sentence is not proven! There is a very definite genetic component to both short and long sightedness as well as the environmental factors above.
So yes you are correct Mario when we were hunters and were hunted that would be an evolutionary disadvantage and probably would cause people to die younger and thus not pass those traits on to the next generation. I suppose the real question now that is no longer a factor is are there any other pressures to cause short or long sightedness to be a positive trait to be "selected for"? There is no reason to think there would be - it could well be neutral and thus not selected for or against. Of note there is a temptation to fall into the trap of thinking all traits must be good or bad!
The ultraviolet (UV) light causes damage to the skin cells which short term causes sunburn and longer term damages those same cells' DNA which increases the risk of those cells becoming malignant (melanoma). Therefore sun creams protect the skin both from sunburn and skin cancer, though nothing is ever absolute - it just reduces the risk since some UV still gets through (which is why one still tans).
All of this is statistics and relative risk it is impossible to say whether a particular day at the beach with or without sun cream will "inevitably" cause cancer.
Stacy Morrow e-mailed me the question below:-
My name is Stacy and I am a senior at Houston High School in the U.S. I love biology and genetics and have read a lot of material by Richard Dawkins, Matt Ridley, etc.
I really enjoy your posts at Ask a Biologist, and it seems you have some expertise in this area. Instead of posting on the site, I decided to e-mail you because it is quite long and detailed.
I was wondering if you could help me in an argument, I want to check my facts.
So, I got into a rather interesting argument with my friend about which sex came "first" in the evolutionary scheme. She seemed to be very "sexist" in the way she presented her side.
Basically, she argued that females obviously did because the Y chromosome was a "broken" X and because there are all-female species that do not need males. She said the first cells, since they were asexually self-replicating, were by definition "female". She contends that females are the natural primary default sex, and that males serve a very limited purpose, mainly evolved just to provide "genetic variation" within the species. She furthered her argument by pointing to embryology, that females are the developmental default and you have to have a Y chromosome to make a male. She told me to ask "any biologist" and that they would tell me the same.
It seems to me that she is twisting certain biological truths to purport a ridiculously sexist agenda.
Now, I know something about the evolution of sex myself, and I argued that there really is no basis to saying that one sex came 'first'. If my knowledge is correct, females are NOT defined by giving birth or even by chromosomal structure, but strictly by the types of gametes they produce (females produce large, immobile ones, and males produce smaller, mobile ones). Now, after reading a bit of Dawkins, I came across the theory of how differing gametes might have evolved. You originally have cells replicating themselves, no males, females or sex. Then, cells start fusing and exchanging genes - sex had arrived on the scene! For some reason, this conferred an evolutionary advantage. So, you now have "isogamous" cells that are the same size reproducing sexually (but, by definition, still no "males" or "females"). So right off the bat, you don't really need males OR females for reproduction, either sexually or asexually. I think some fungi still reproduce this way. Anyhow, among these medium-sized mobile cells, some gametes just happened to be larger than others. This may have been favored, because larger cells have more nutrition. So, cells got larger. Then, the smaller cells decided to cash in and "exploit" the resources of the larger cells. This became advantageous (to be smaller), because it cost less energy to make these cells if they fused with bigger ones. The large cells become larger to compensate for the nutrition-scarce smaller cells. So, in a runaway fashion, you get smaller, faster cells and larger, less mobile ones. Eventually, the really large ones become immobile (because they are constantly chased by small exploiters) and the smaller ones get even smaller and faster. These become, in time, eggs and sperm respectively. So the gametes seem to evolve in response to the other. In reality, you do not have one without the other.
Then, when you get to organisms, originally individuals produce both types of cells (hermaphrodites) and at some point there is a split where one individual produces only one type of sex cell. In response to my friend, in some worms, I think there are only males and hermaphrodites, so it is possible that either sex "split" first.
As far as her chromosome argument is concerned, I think it is just an evolutionary coincidence that females are homogametic, and therefore "default" in development and males heterogametic. In birds, I read that default development is male and it is females that have the smaller Y-like chromosome (termed W). Males are not losing any genetic information (they also have an X chromosome), and we had "males" before the Y chromosome (some types of mammals have lost the Y chromosome and still have males!) There is no reason to think that females are more "basic" or fundamental in anyway.
And finally, with regard to parthenogenesis, the reason these species are all-female is simply because females produce nutritional gametes, therefore any selection pressure that favored asexuality would, out of necessity, have to go through the female line. It does not prove that females came first, because in actuality these asexual species were once sexually reproducing - in other words, they originally had males! It raises, however, an evolutionary question of "why have males at all," simply because it seems a better way to reproduce than by chucking away half your genome to have sex. It is not about how males evolved, or why they appeared, as my friend states, by why they do not disappear! Why would a female put up with the cost of sex, when males don't contribute much materially? There have been several reasons given, the parasite theory of Ridley's book, or the theory that sex covers up bad mutations. Whatever it is, the cost of sex (and incidentally, males) is HUGE, and the fact that sex is ubiquitous means that males are maintained for a very, very important reason, certainly no "limited purpose".
Nevertheless, I argued that no organism is interested in anything beyond spreading its own genes - males did not originate for female's purposes or the purposes of the species - the fact that they perform a vital function in evolution is purely incidental (as is females'). Also, it doesn't really matter in our own species, since natural asexuality is genetically impossible (think genomic imprinting). From a gene's perspective, the male strategy and the female strategy are, on average, equally good. Nature, therefore, values the two sexes equally and will invest equally in them (even if it isn't for the "good of the species"), so arguments for overall superiority of one sex are futile.
That was basically my argument, and it's been a while since I've read any good books on biology. So are my facts accurate? Did I make a good case? That's basically why I'm e-mailing. Sorry that this was so long, but I'm sure you'll find it interesting!
30th Jul 2010 13:57:15
Re: Infectious diseases and blood/organ donation (posted in Human Biology and Evolution)
The NHS exclsion criteria are below:-
http://www.heron.nhs.uk/specialist_dire … #Exclusion Criteria
In the case of "old" treated viral or bacterial infections it will be considered on a case by case basis but by and large the answer will usually be that it is OK.
The forward facing knee significantly improves our ability to run whilst upright. Wiki has a number if useful pages on this (search for "running"). The previous post below is also of some relevenace.
You should be fine since the amount of methanol you will have absorbed through your skin will be limited. Your actions in terms of washing was sensible. As to the drinks that evening - nice idea but not sure it will have contributed much either way!
The link below provides protocols for DNA extraction for many species and situations:-
http://www.protocol-online.org/prot/Mol … index.html
As to mixing DNA to "make a new creature" I am afraid it is not quite that simple! I suggest you do a bit more reading round the subject and then post again.
28th Jun 2010 14:32:13
Re: When we will be able to clone a mammoth? (posted in Genes, Genetics and DNA)
To clone a mammoth would need a lot of things that are not available. At the top of the list would be the need to harvest a nucleus from a live mammoth cell which by definition is not available since they are extinct.
I am not saying it will never be possible - just not at present given our current state of technology and imperfect understanding of the science of cloning.
Please take a picture upload it to the site and then we may be able to help identify it.
24th Jun 2010 15:59:09
Re: large insect found in house (posted in Invertebrates (Including Insects))
Here is the link to Margaret's picture
24th Jun 2010 15:58:24
Re: photo for previous question (posted in Invertebrates (Including Insects))
Thanks I have linked this to your previous question.
My strong advice is do not overdo your drinking and certainly not for prolonged periods. As a physician I see more and more and younger and younger people whose lives are ruined by alcohol. Only last week I saw a 23 year old girl die of acute alcohol poisoning and less than a month ago a 34 year old man (previously worked in finance) who died of end stage alcoholic cirrhosis.
To answer your questions:
By far the biggest contributor to the hangover is dehydration followed by hypoglycaemia. Both cause the headache and nausea. In addition depening on the amount of alcohol and vomiting you will develop inflammation of the stomach (gastritis).
Reducing/minimising the hangover (other than the obvious of not drinking to excess): drink lots of water during and after the alcohol intake, and during the night (assuming you are concious). The next morning no "hair of the dog" or cooked breakfast - more water, two paracetamol (no more your liver won't take it) and something relatively sweet to drink. Do NOT take asprin your stomach will be inflammed enough already!
22nd Jun 2010 16:45:56
Re: Diabetes, the immune system, and glucose levels (posted in General Biology)
Both good ideas and simple answer is we are still not sure. My best "guess" (as a diabetologist) would be the infections (viral or bacterial) cause the release of a whole host of various inflammatory mediators (including chemokines and cytokines) which in turn have very powerful effects on the sensitivity of your tissues to the insulin. That explains why it is so common in infections for the insulin requirements to go up. Why the insulin requirement would transiently go down is less clear, and clinically I have not observed that but I do not for an instant doubt what you say since your monitoring is far more rigorous that what we would normally do in a hospital setting!
I am sorry but the pictures above are so small it is very difficult to make any comment on them. Could you post some more with higher resolution that are larger please?
There is almost no rigorous scientific evidence to backup the theories of body types and sports etc. Given it is most unlikely to apply to humans I can see no reason to think it will apply to animals either!
Both! The venom is a mixture of a number of chemicals that are highly toxic to most species and since it is a method of killing prey and of defence it is also a "biological weapon".
This is a UK based website so we probably are not the best peopleto ask. Further it depends in part what career you wish to pursue once you have completed your degree. I suggest you look at the websites of the two universities and compare the modules and think which would interest you more. Seek advice from your school's career service and ask how the universities compare in terms of local, state and country rankings - in other words all other things being equal which is the more prestigious degree.
Good luck with your studies.
I am sorry Jacky but it would seem no one knows the answer to your question.
I am sorry Sara but it would seem no one knows the answer to your question.
16th Jun 2010 11:08:48
Re: Smallest multicellular organism (posted in Microorganisms (Bacteria, Viruses, etc.))
There are no two-cell organisms I know of (other than during development). I think the answer to your follow-up are the worms eg c-elegans.
Thanks
For reasons that are not entirely clear to me we get a very large number of questions about a career in herpetology from people who live in India. If you browse the careers forum you will see your question has been answered previously. Good luck with your career.
I doubt it is human Paolo, the size of body vs the canal and facets is too large IMHO. I would guess its more likely to be pig or possibly even cow.
Yes they can though it is much rarer than in boys.
Red-green colour blindness (and there are other forms which have different genetic inheritance patterns) is an X-linked condition, so usually as you say females carry the disease but do not suffer from it since they have one "normal" copy of the gene on the other X-chromosome. However if the father suffers from the disease and the mother is a carrier then female offspring will inherit mutated copies of both their X-chromosomes and thus also suffer from the disease.
Mike then replied to Stuart:-
Sorrry I wasn't more specific etc.
To repeat my quetion with more detail.
We have now identified the beetle walking across our carpet as a Dogbane Beetle. The picture was on another sight and was an exact match.
We live in Northumberland, U.K. and therefore we were puzzled how an American beetle got to us. We haven't had any obvious fruit, veg. or other materials from the U.S. as far as we know.
This question has been asked many times before. If you search or browse the careers forum you should find the answers you are looking for.
This question has been asked many times before. If you search or browse the careers forum you should find the answers you are looking for.
12th Jun 2010 15:26:13
Re: How to become a Tv host In National Geographic Channel (posted in Research and Careers)
What ever you decide to do in life, learning to spell and to write full and grammatically correct sentences will be a great asset.
Actually no! The latest data (and this is a rapidly evolving field) demonstrates that C-fibre nociceptors are also important for itch, though in addition some subclasses of A-fibres are also needed for the full response. Also to note all of the current studies have been done in rodents, we do not know yet whether these new findings will be applicable to man, though the assumption is yes.
David Hone
David Wynick
Jerome Feldmann
