In article <3v3ihj$3ki at news.bu.edu>, pariser at bio.bu.edu (Harold Pariser) wrote:
> I am curious to know if agnathans have 2 or 4 hox gene clusters. It
> is a widely held view that all vertebrates have four hox clusters but
> I have not seen any literature conclusively showing this in agnathans.
Apparently Hox clusters in agnathans have not been studied in detail (1994).
But Ruddle and coworkers have cloned a bunch of homeobox genes from agnathans.
In the following paper they suggest that lampreys have 3 Hox clusters (although
they also propose that amphioxus has 2, which has been disproven in the
Garcia-Fernandez paper mentioned below).
RA Pendleton J.W., Nagai B.K., Murtha M.T., Ruddle F.H.;
RT "Expansion of the Hox gene family and the evolution of chordates";
RL Proc. Natl. Acad. Sci. U.S.A. 90:6300-6304(1993).
Amphioxus has only one Hox cluster; see:
RA Garcia-Fernandez J., Holland P.W.;
RT "Archetypal organisation of the amphioxus Hox gene cluster";
RL Nature 370:563-566(1994).
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