Worm Breeder's Gazette 8(1): 37
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.
We have continued our study of the four nematode actin genes. The complete nucleotide sequences of the clustered genes I, II and III are now available, and most of gene IV has been sequenced. The coding regions of genes I and III are identical at the nucleotide level. When compared to genes I and III, genes II and IV have many silent substitutions. Gene II has three conservative amino acid changes; and gene IV has at least one amino acid change similar to gene II. Genes I, II and III each have two introns in identical positions; gene IV has three introns, only one of which interrupts at a position similar to the introns in the clustered genes. We are now studying actin transcription during development in wild- type worms and in revertant worms in which reversion is accompanied by DNA rearrangements of the actin cluster. When Northern blots are probed with actin DNA, a triplet of bands is seen at all developmental stages in wild-type worms. The amount of actin message increases markedly between the L2 and L4 stages. A gene I specific probe shows hybridization exclusively to the middle band of the triplet. In revertants, the number and size of the actin transcripts varies. We have used the gene I specific probe to demonstrate the absence of a stable gene I transcript in a revertant containing an insertion in gene I. The exact nature of the variations in this and other revertants is now being studied using other gene-specific probes.