Worm Breeder's Gazette 11(5): 20
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.
Cyclin proteins are intimately involved in cell cycle regulation. Two types of cyclin proteins have been identified, cyclin A and cyclin B. The cyclin A protein has been shown to be critical to embryonic development in Drosophila; homozygous mutant embryos lacking cyclin A die when zygotic transcription fails to provide cyclin A. The presence of cyclin B protein cannot rescue these mutants (C.F. Lehner and P.H. O'Farrell, Cell 1990. 61:535-547). No mutants in cyclin B have been reported in Drosophila. Cyclin B protein has been shown to be involved in meiotic maturation in clams (Westendorf et al., J. Cell Biol. 1989. 108:1431-1444). Perhaps surprisingly, in Drosophila the mRNA for cyclin B localizes by in situ hybridization to the Drosophila pole cells, the fly equivalents of the nematode P germline cell lineage (Whitfield et al., Nature 1989. 338:337340). The Bennett laboratory is interested in the nematode germline lineage and in identifying the components of the germline P granules ( Strome and Wood, Cell 1983. 35:15-25 and K. Bennett, WBG 9:1 55). We plan to determine if nematode cyclin B RNA is similarly localized to the nematode germline precursor cells, and would like to address what possible role the sequestration of cyclin B RNA plays in the determination of the germline. Using primers to conserved cyclin B regions, we have isolated, cloned and sequenced a PCR product from genomic Caenorhabditis DNA which is a putative cyclin B. As illustrated below, this fragment has 72% exact match at the amino acid level to the corresponding region of the clam or sea urchin cyclin B genes; this is exactly the same match ( 41/57 aa) that sea urchin and clam show to each other in this region. Southern blot analysis using this fragment as a probe with C. elegans DNA indicates a single copy gene. The PCR fragment recognizes a single 1.4 kb message on Northern analysis using polyA+ RNA from mixed stage worms; this size is large enough to accommodate the coding region of the cyclin B protein. We have recently screened R. Barstead's lambda ZAP mixed stage cDNA library. Thirty putative cyclin B cDNAs were detected on duplicate lifts when 120,000 phage were screened. [See Figure 1]