Worm Breeder's Gazette 9(3): 69
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
There are two heptamers repeated multiple times upstream of the C.
enin genes. In order to obtain evidence for
or against the functional importance of these heptamers we have
investigated their evolutionary stability. We sequenced the homologous
promoters from C. briggsae and the only C.
enin promoter remaining unsequenced vit-3.
This brings the total number of nematode vitellogenin promoters
sequenced to eleven. The data are shown schematically in the Figure.
Box 1 TGTCAAT, is shown as rectangles; Box 2 CTGATAA is shown as ovals.
In general the heptamers have beer very highly conserved while the
sequences between them have diverged considerably. In particular there
has been strong conservation of the Box 1 heptamers centered at -45 (
just upstream of the TArA box)those at -180 (which we have suggested
may be at the 5' border of the promoter regions) and at least one Box
1 between -45 and -180. In each case the locations and sequences of at
least these Box 1 heptamers and at least one Box 2 heptamer per
promoter have been conserved. This data strongly supports the
hypothesis that Box 1 and Box 2 are involved in vit promoter function.
We are initiating experiments to determine the relationship between
the two heptamers and the three modes of regulation: sex stage and
tissue.
{Figure
1}
We have noted previously the presence of Box 2 in the vertebrate
vitellogenin promoters. Klein-Hitpass et al. (Cell 46 1053) have
tested the idea that this heptamer plays a role in Xenopus
vitellogenin gene induction by estrogen in a transient expression
assay using a human mammary cell line. They present evidence that it
is a binding site for an activator protein required for estrogen
induction but not the site for estrogen receptor itself. They name it
the 'elegans box'. Does this mean that the regulatory protein that
binds to this sequence in the C. e is also
present in human mammary cells?