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ECB-ART-39686
EMBO J 1982 Jan 01;11:27-33. doi: 10.1002/j.1460-2075.1982.tb01119.x.
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An unusual evolutionary behaviour of a sea urchin histone gene cluster.

Busslinger M , Rusconi S , Birnstiel ML .


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DNA sequences of cloned histone coding sequences and spacers of sea urchin species that diverged long ago in evolution were compared. The highly repeated H4 and H3 genes active during early embryogenesis had evolved (in their silent sites) at a rate (0.5-0.6% base changes/Myr) similar to single-copy protein-coding genes and nearly as fast as spacer DNA (0.7% base changes/Myr) and unique DNA. Thus, evolution in the major histone genes conforms to a universal evolutionary clock based on the rate of base sequence change. By contrast, the H4 and H3 coding sequences and a non-transcribed spacer of the DNA clone h19 of Psammechinus miliaris show an exceptionally low rate of sequence evolution only 1/100 to 1/200 that predicted from the clock hypothesis. According to the classical model of gene inheritance, the h19 DNA sequences in the Psammechinus genome require unusual conservation mechanisms by selection at the level of the gene and spacer sequences. An alternative explanation could be recent horizontal gene transfer of a histone gene cluster from the very distantly related Strongylocentrotus dröbachiensis to the P. miliaris genome.

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Genes referenced: ago1b clock LOC100887844

References [+] :
Benveniste, Evolution of C-type viral genes: inheritance of exogenously acquired viral genes. 1974, Pubmed