Worm Breeder's Gazette 14(2): 78 (February 1, 1996)

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.

Temperature sensitive sterile uncoordinated mutants define genes required for cell division

Kevin F. O'Connell, Charles M. Leys, John G. White

Laboratory of Molecular Biology, University of Wisconsin, Madison, WI 53706

We are interested in studying various aspects of asymmetric cell cleavage, among them the mechanism that determines the position of cell cleavage planes, during the well characterized embryonic divisions of C. elegans. A genetic screen capable of isolating a large collection of conditional cell division mutants has been devised. Isolation of these mutants relies upon expression of two developmental-stage specific phenotypes. Lethality is expected among the progeny of a mutant adult shifted to the nonpermissive temperature as the embryonic cell divisions should fail, while a viable but sterile uncoordinated phenotype is expected of an animal shifted following embryogenesis, as the divisions of the postembryonically-developing gonad and ventral nervous system should be affected. Specifically, the screening format involves a selection method to generate pools of mutants that exhibit a conditional embryonic lethal phenotype.! These pools are then screened for the presence of a postembryonic sterile uncoordinated phenotype. To date an estimated 50,000 haploid genomes have been screened and 29 mutant lines that meet these criteria have been isolated. Preliminary analysis indicates that embryos from many of these mutant lines exhibit obvious cytological defects including defects in cytokinesis, centrosome activity, and spindle alignment. A summary of mutants with known cytological defects is presented below. We are continuing to characterize these mutants as well as isolate additional mutants.

Mutation      Map position        Cytological defect

oj2ts                  V                Defective polar body

oj5ts                  I                Cytokinesis defective
                                        /spindle abnormal

oj7ts                  II               Centrosome duplication
                                        /separation defective

oj8ts                  -                Multinucleate blastomeres 

oj10ts                 -                Multinucleate blastomeres

oj14ts                 I                Abnormal spindle alignment 

oj18ts                 -                Abnormal spindle alignment

oj29ts                 -                Putative centrosome
                                        duplication /separation