A synthetic Multivulva phenotype can result from mutations in two separate genes, while each mutation alone results in an apparently wild-type phenotype (Ferguson and Horvitz, Genetics 123:109-121,1989). Mutations that can cause this synthetic Multivulva (syn Muv) phenotype have been grouped into two classes, A and B, such that a double mutant carrying one mutation in each class will have the syn Muv phenotype. Iin-9
(nll2) III is a class B mutation that results in an apparently wild-type phenotype by itself. We previously reported that ZK637 and overlapping cosmids can rescue
lin-9 (WBG 11(2 ): p 29,1990). We have now identified an 8 kb subclone with rescuing activity. Using this 8 kb fragment to probe Stuart Kim's cDNA library, six positive plaques representing at least three independent clones were isolated. This 8 kb probe also detects a message of approximately 2.5 kb on Northern blots. The message level appears similar in eggs and mixed-stage populations. We are currently sequencing these cDNAs and looking for evidence that these transcripts do in fact represent the
lin-9 gene. This work will be greatly aided by the genomic sequence provided by Molly Craxton, John Sulston and Alan Coulson, as ZK637 was fortuitously chosen as one of the first cosmids to be sequenced in the worm genome sequencing project.