mattbimbo

i looked up a relevant paper on M1CR polymorphism, ie the red gene: http://http:www.pubmedcentral.gov/articlerender.fcgi?tool=pubmed&pubmedid=10733465 this paper has been used by some as evidence of N-C hybrids. the paper will take me another reading or two, but on first browsing it doesn't really point in favour of any hypothesis. in fact it plays down its results and conclusions.

maybe there will be evidence in the gene pool, but this evidence would only be valid with the analysis of genetic material from fossils. if N-genes are found in present day caucasoid genetic material there will always be the counter-argument of horizontal/lateral gene transfer. i won't bring up the ginger gene in this context, the mutations only occur in single codons, instead i will just point out that ginger is not limited too caucasoids: http://en.wikipedia.org/wiki/Red_hair

as regards the legacy of N-genes in caucasoids i will keep an open-and-infantile mind. don't all hypotheses have holes in them? i am, like you, in two minds about the mitochondrial data. i think your criticism of how this data is interpreted is valid. it is considerably easier to isolate sufficient amounts of intact mitochondrial DNA for sequence analysis compared to genomic DNA, this practical point biases the data - nevermind the interpretation of the data. likewise, the considerable paucity of data and difficulty, more ethical than technical, of performing hybridization expts in mammals also creates a bias. can anyone think of any expts which would overwhelmingly demonstrate the legacy of N-genes in caucasoids? the reason i ask this question is that i am most curious about whether it is in our ability as scientists to find an answer. one day someone may recreate germ cells from N-man and N-woman and see if they can fertilise or be fertilised. however even if this was done, it wouldn't be the final experiment because there are a range of immunological factors that determine fertility in vivo and also they wouldn't measure the survival fitness of the offspring. there are more obvious experiments i could think of, but these would be flawed too.

Peon, chill out <smily>. i think you have discussed this issue seriously and intelligently. i had never thought of its genetic aspects before, and now i have. it seems you had, but then it seemed you hadn't. if you don't know whether it is a 'one in a billion' chance or not of successful interbreeding, despite all your reading and analysis, that's ok and you can pass the buck if you want.

i did find this link related to chromosome number and mating http://http:www.gate.net/~rwms/EvoEvidence.html i would like more examples, and a mechanistic explanation of the Prezwalski/domestic horse hybridization event in relation to sequence similarity and the formation of trivalent chromosomes at meiosis, but this is a bit of a plus for you Peon <semi-smilie>. so do you think there were singles bars in N-times?

hi peon, with all your expertise on this subject can you give me an estimate of how frequently N-person and H-person would have to have successfully produced offspring for there to be a significant N-gene legacy in caucasoids?

NK cells have always been considered to be the evolutionary precursors of DCs. it is not suprising to me that an intermediate type of cell has been isolated. what bothers me, is if they constitute 10% of the spleen, why they weren't found earlier! with a paper like this it is important to wait for the papers which confirm its observations; there are factors known to drastically alter the DC content of the spleen.

hi ps2huang, you have been very open. i'd recommend you read Stephen Chang's book, 'The Complete System of Internal Exercises'. the pulsing exercises he describes might help you.

hi peon, if you so readily resort to one in a billion arguments, this in my opinion is bad science! when giving the quick reply there are no smilies. the point i should have made is that there is no need for us to develop greater DNA technology, as you seemed to think important, more of a need for expts. though i have never looked into it before, it seems there is very little research on hybridization and ploidy in mammals, so why dismiss it, especially when there is an enormous amount of research on polyploidy in relation to embryogenesis and tumorogenesis.

you are right the adrenal glands lie adjacent to the kidneys, but still i wouldn't want to be without them.

TIR occurs at the interface of two media. the angle of TIR is determined by the relative refractive indices of the two media.

hi peon, as regards ploidy, i am not the one to give you a complete answer. i am just working from a few scraps of information. 1) >30% of human fertilised eggs self-abort (forgive the term self-abort) - more than any other species. why? human embryo development is very complex. even at the one cell stage, there are many 'checkpoints' the cell has to go through before it will replicate. one of these 'checkpoints' involves some kind of chromosome counting. there is an obvious need for chromsome counting and without it any species would quickly die. mutation is important, but too much mutation is deadly. note, primitive organisms including fungii count chromosomes. 2) and this chromosome counting goes occurs not only in fertilised eggs, but in all replicating cells, for instance haematopioetic stem cells. again for the same obvious need and without it we would develop cancers at such an extraordinary rate that if we survived to birth we would be more tumour than human. note, there are many connections between embryo and tumour development. but someone will ask what is the obvious need? gene dosage, my N-friends! too many copies of a gene upsets the balance. perhaps you know, females have two x chromosomes but one of them is switched off at the time of conception. (amazingly yes, there is some kind of natural selection going on within a single fertilized egg for the best x chromsome in females.) think it through...doesn't it make sense for cells to have evolved mechanisms to prevent outrageous gene dosage mutations such as altered chromosome numbers. 3) there is an old theory in cancer biology which is now gaining some favour again involving ploidy. the first microscopic observations of cancer cells showed that they frequently inherited the wrong number of chromsomes. now the theory of cancer evolution has pretty much became fixed on the multiple hit hypothesis for tumourogeneis. however there is the strange observation that many of the key genes which are mutated in cancers are the same genes; for instance in the Ras genes often the same amino acid, eg K14, is mutated; but how can one codon be so fragile that it keeps on giving rise to cancers? this is where the polyploidy-first hypothesis of cancer gains in credence because it goes someway to explaining this seemingly unfeasible situation. and here goes, if a cell loses or gains chromsome material this will alter the gene dosage of the cell. now the cell has mechanisms to detect this and the result will normally lead to apoptosis of the cell. but a cell can make mistakes; no mechanism will be perfect. this will lead to a situation where the cell will try to adapt to its new genetic makeup. theory predicts that such adaptation would be expected to favour mutation of key genes, such as Ras genes, which are central to many signalling pathways. i know my explanations aren't very erudite, but i hope they get you thinking. yes, i find it strange that no one has thought the ploidy question through. this is not an answer but i think you will find as you get older that there are a lot more bad scientists than good ones. maybe in the interests of science you should contribute to this question by sleeping with a great ape in the nearest zoo? just dangle some juicy bananas though the bars.

yes, the phenomenon of TIR causes 100% reflection of the incident wave. well maybe not 100%, but close to, because there is a phenomena involving TIR and the propagation of an evanescent wave.

just to continue the liver-kidney axis: vitamin D is first activated in the liver then the kidney.

i have to stick to the ploidy and mating question. don't the wolf and coyote have the same number of chromosomes? 39 pairs, or 38 pairs if, like me, you don't count x-y as a pair.

intestinal flora too can influence blood alcohol levels. our stomachs, to varying degrees, are producing alcohols, including ethanol, all the time.

it is a good topic but my main concern is the mating problem, 24 + 23 = 47 ! i want to use the term aneuploidy but i am not sure how it applies. is there any research where mating can occur between species of different chromosome number? i did find a reference http://news.bbc.co.uk/1/hi/sci/tech/1323485.stm reporting that no neanderthal genes were found on the Y chromosome. i am not sure of the significance of this but i have read that >90% of the Y chromosome is a gene junk yard.

well i don't agree - there are recent reports (last 5-10 years) that the kidney produces up to 20% of the bodies glucose - in fact gluconeogenesis by the kidney is considered to be constant and doesn't undergo circadian rythyms unlike gluconeogeneis by the liver - and in conditions of liver damage, gluconeogenesis by the liver increases - in the same situation the kidney will produce bile acids. also the kidney is the site of the adrenal glands... which i wouldn't want to be without.

i don't especially want get into this question again, because it is a bad question, but to write an answer in favour of kinetics and not thermodynamics is potentially misleading. if something is TEMPERATURE DEPENDENT how can thermodynamics be irrelevant? need i say more? (but i concur with most of Yggdrasil's reasoning.) and 40C - humid - what nonsense? the enzyme works in solution, ie 100% humidity.

oh bugger, i should be more careful. maybe N-woman was a one N-man doll?

i have learnt much from this thread! questions which now interests me, inspired by this thread, is whether a great ape (with 48 chromosomes like N-man) and a human have ever successfully mated? was N-man mostly a one N-woman guy (i am curious did they mate like homo sapiens too)? anyone got a good explanation for why N-men went extinct?

all the molecules within a single cell are being constantly remade. it is the ability to make these molecules that persists within the cell rather than any molecule. this ultimately depends on nucleic acids, but neither do nucleic acids persist. every time a cell divides its nucleic acid molecules are remade. what is inherited over the long-term are particular sequences, the genes, within nucleic acids. only genes provide the continuity needed for the evolution of life. but genes don't have to be embodied in nucleic acids do they? in his early career Pauling worked on antibodies, and by 1940 with Delbruck proposed that biological specificity resulted from the detailed complementariness of two molecules. by 1948 he wrote about the gene, "If the structure that serves as a template consists of, say, two parts, which are themselves complementary in structure, then each of these parts can serve as the mold for the production of a replica of the other part, and the complex of two complementary parts thus can serve as the mold for the production of duplicates of itself" of course 5 years later the mold was discovered to be dna, but when the gene is described this way it is easy to see that nucleic acid is not a universal molecule. indeed as argued by AG Cairns-Smith, nucleic acids may well have evolved from a pool of self-complementary molecules, in his book Genetic Takeover, he goes on to explain in broad evolutionary concepts why nucleic acids may have succeeded over other types of molecules. in this book however he doesn't consider whether some other molecule might come along and takeover from nucleic acids.

anyhow i don't think that because marriage is an unglamorous state i should exclude the possibility of marrying a model. my model wife may only look good for the camera. my younger brother, tim, works as a digital printer and spends most of his day improving skin, tits and arses for all the super models.

yes, plastic surgery can be looked on that way. but i understand that many young women have plastic surgery. i don't know the reasons but i expect it has something to do with feeling better about themselves and is this so bad? but it was a stupid thing to write, my apologies.

plastic surgeons can help too