Worm Breeder's Gazette 13(5): 51 (February 1, 1995)

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.

sy275 Males Have a Defect in the Migration and Attachment of the Linker Cell.

R.E. Palmer, P.W. Sternberg

HHMI and Division of Biology, Caltech, Pasadena, CA 91125

We have previously described the isolation of an egg-laying
defective mutant with an abnormal contact between the
anchor cell and the vulval precursor cells (WBG 13:3).
L3 hermaphrodites homozygous for the sy275 mutation have
an abnormal contact between the anchor cell and P6.pap
and P6.ppa, i.e., the anchor cell fails to invaginate between
the P6.pap and P6.ppa and is often observe on top of the two
cells. In mid-L4 hermaphrodites the connection between
the uterus and the vulva appears obstructed suggesting
that the connection between these two structures is disrupted
in this mutant. Hermaphrodites with sy275 in trans to the
translocation mnT11 (used as a deficiency, see Herman
et. al. Genetics 1982) are egg-laying defective and their
brood size is decreased by ~10 fold. In addition, approximately
5percent of the animals are sterile. Other evidence suggesting
that sy275 is not a complete loss-of-function allele is
that 5percent of sy275 hermaphrodites grown at 25 C are
sterile (n=275). We are presently, conducting a non-complementation
screen to identify additional alleles.
We had previously reported that sy275 males are mating
competent, however, quantitative mating experiments
indicate that only 30percent of the males tested were able
to sire cross progeny (n=50). Examination of sy275 males
with Nomarski optics suggests that there may be two linker
cell specific defects. In about 30percent of the adult
males examined the linker cell had not migrated more than
1/2 way down the ventral side of the animal. Interestingly,
the intestines of these worms were completely distended
and full of bacteria suggesting that the animals were unable
to defecate. In approximately another 30percent of the
adult males examined ectopic sperm were present in the
body cavity. Ectopic sperm were only observed in mated
males but not in virgin adult males. Anatomical observation
suggests that in about 30percent of late L4 or young adult
males the linker cell, while it has migrated into the tail,
has not attached to the proctodeum properly. Thus, sy275
disrupts two analogous cell attachments - the anchor cell
to vulva and linker cell to proctodeum.