What about those jumping genes?

I thought something along those lines as well, that saliva might carry some cells, such as cheek cells in humans. Not that this then necessarily leads to a pathway for genetic transfer.TTFN,WK

Really, that sounds wrong to me. It takes a heck of a lot of work to maintain RNAs in a sufficiently stable state for analysis but you are suggesting that a potentially days old licked envelope will have sufficient recoverable sequence to allow a viable genetic fingerprint to be retrieved?I'd have thought that DNA contained in leftover cheek or tongue epithelial cells would be a more viable source of genetic information. I've sent plenty of plasmids out on dried filter paper, but I've never sent RNA samples out that way.TTFN,WK

Neither cite says anything about recovering RNA from dried saliva and using it for genetic fingerprinting.I wasn't suggesting there was no RNA in Saliva. What I was saying was that the recovery of genetic material for DNA fingerprinting from an item such as an envelope was not based on RNA, as you had claimed.I see you have just now posted something about the recovery of DNA form stamps, good show.TTFN,WK

Come on Hoot, you've gone from ... to Suddenly the tenuous connection you were drawing, with no evidence to support it, is supposed to be expert opinion from Bushman? The incorporation of viral sequences or sequences from organelles both involve genetic sequence already on the inside of the cell membrane and either present or capable of propagating to cells throughout the body.There is no need for some magical route for DNA from a tsetse cell in saliva to be incorporated into the genomic DNA of a gamete in order to explain Bushman's statement, just the known factors such as retroviral insertion and transposase activity.There may be some unknown mechanism of DNA incorporation out there but you have given us no reason to suppose they exist as the current known routes are sufficient to account for the elements you have brought up.Perhaps a more suitable avenue to explore for your approach would be the mechanisms leading to the incorporation of mitochondrial genetic elements into the nuclear genome (Schmidt and Blanchard, 1996). But you still have along way to got to make any sort of case that such a mechanism is required or indeed that there is anything to be explained.TTFN,WK

Except you don't seem to have made a case.Without some actual reference to determine what sequences that were studied actually were there is nothing but the claims Brass et al. made in their report to the MAFF to allow us to determine how close the sequences actually were. BLASTing the 3 sequences on pubmed does turn up one with a 75% similarity to a human sequence, but whether this is the sequences that Brass's group studied is unclear.So apart from this homology why are we to believe there has been some direct HGT between tsetse and human? And if because simply of this homology what should presuppose us to believe that it is the result of direct HGT?TTFN,WK

The fullest account available that I can find seems to be the from a report to the Novel Foods and Processes Advisory Committee.This report doesn't really give any more detail of the methodology than New Scientist did. It sounds like they just used publicly available sequences from Genbank and I can only find 3 such sequences linked to the mariner transposon. Of these one 'Glossina palpalis Tsetse.fly.3 mariner transposase gene, partial cds', which I already mentioned, pulls out human mariner sequences with high levels of similarity.However if you take that similar human sequence and BLAST it you will not get the Tsetse sequence coming out as the highest non-human hit. There are several primate sequences before it, as well as sheep and cow sequences. It seems much more likely that the Tsetse fly has at some point acquired the transposon, through whatever vector, from the primate lineage than the other way round. I'd agree with molbiogirl that it seems much more plausible for some infective vector such as a virus or intracellular parasite to act as the carrier of the transposon than for their to be any incorporation of naked DNA in either direction directly between human and fly.The report makes the rather vague statement... Which unfortunately is so vague it doesn't allow us to discriminate between the two scenarios to work out what the authors thought occurred.I would be quite happy to agree there is some evidence for a transfer of genetic material between the human primate lineage and the Tsetse fly but I strongly contest that there is any evidence that such a transfer would involve the incorporation of naked DNA directly from one to the other over its having been transmitted by some sort of infective vector. Molbiogirl's alternative hypothesis that the common sequence is the result of transmission from some common infective vector in both cases seems equally viable.TTFN,WK

This just strikes me as arrant nonsense. It sounds like the informational equivalent of all the spurious appeals to quantum physics made by the purveyors of woo to support any ludicrous claim they fancy.Do you have any conceivable method by which such information could be transmitted between organisms independent of their molecular medium?TTFN,WK

So that would be a no.If you think that is what a jumping gene is then once again you have shown that rather than biology you prefer the science of making rubbish up and glib nonsense.TTFN,WK

DNA as a rule does not jump. Transposons do because of particular properties of their sequence. Transposons are made of DNA but not all DNA is equivalent to a transposon.TTFN,WK

Which was shockingly exactly the conclusion you had already arrived at before looking at that information and one still totally unsupported by the facts.Just look at that tree! You might as well say we have flatworm DNA or Cnidarian DNA jumping around in our genomes. If anything the tree casts serious doubts on any sort of direct insect to human transition, and even more if they had included other primates which would virtually all have treed out with H. sapiens.If you had an ounce of integrity you could reach the same conclusion that molbiogirl and I have been suggesting for this whole thread. That rather than all of these similar sequences being transferred from species to species their distribution is more consistent with their being introduced from a common infective source, such as an intracellular parasite or virus.The sequence being similar to that found in insects no more makes it 'Insect DNA' than the fact that hundreds of genes being highly similar to invertebrate forms due to the restrictions of biochemistry on their function makes those conserved genes 'Insect DNA'.TTFN,WK