Worm Breeder's Gazette 15(5): 28 (February 1, 1999)

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.

KEL-1, a homologue of Drosophila Kelch, is essential for larval development

Mitsue Ohmachi1, Asako Sugimoto1, Yuichi Iino2, Masayuki Yamamoto1

1 Department of Biopysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, 113, Japan.
2 Molecular Genetics Research Laboratory, University of Tokyo, Hongo, 113, Japan.

  We have isolated twelve C. elegans cDNAs that trans-complemented the
fission yeast mes1 mutation, which causes a defect in the second meiotic
division (1, 2). Half of these cDNAs encoded cytoskeletal proteins (two
alpha-tubulin, two beta-tubulin and two actin genes) suggesting the
importance of cytoskeletal rearrengement in meiosisII. We further
characterized one of the genes isolated in this screen, which we named
kel-1. kel-1 encodes a 618-amino-acid polypeptide that shows similarity
with Drosophila Kelch throughout the protein, which is known to be
essential for oogenesis. Mammalian NRP/B, which has been implicated in
neuronal differentiation also showed overall similarity with KEL-1.
These proteins carry a motif called "kelch repeat" which consists of two
to seven repeats of ~50 amino acids. KEL-1 also showed weak similarity
with C.elegans SPE-26 and Limulus alpha- and beta-Scruin in this motif.
Although many kelch repeat-containing proteins have been found from
various species, the function of this motif is still unclear except that
alpha-Scruin is known to interact with actin.
  To investigate the function of the kel-1 gene product, animals
mutagenized with UV-trimethylpsoralen were screened for deletion alleles
and one deletion allele, kel-1(pe201), was isolated. This kel-1 deletion
mutant, which lacks most of the polypeptide, arrested at the early
larval stage. However, most mutant animals were not dead soon after the
arrest. They survived for several days after hatching and their movement
and morphology was essentially normal, except that they accumulated
granules throughout their bodies. We investigated the localization of
KEL-1 using anti-KEL-1 antibodies and a kel-1::GFP reporter. KEL-1
localized to the pharyngeal g1 gland cells at all stages after late
embryogenesis. The g1 gland cells have been suggested to play a role in
molting and digestion. L1 lethargus and subsequent molting occurred in
the kel-1 deletion mutants, although slightly later than control
animals. We speculate that the most likely reason for the developmental
arrest is that the kel-1 deletion mutants cannot feed effectively.

1. Hayasizaki et al. (1998) Genes to cells 3, 189-202
2. Ohmachi et al. (1998) Midwest worm Meeting Abstract 79