Worm Breeder's Gazette 7(1): 53
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 begun an analysis of the structure of C. genes with the eventual goal of studying the regulation of their expression during development and of identifying mutants that affect histone gene expression. So far we have carried out preliminary mapping experiments on three phages carrying C. genes, and are in the process of studying 19 others. Phages were isolated from a lambda1059 clone bank carrying 15 kb Sau3A Bristol fragments, using as a probe a cloned sea urchin histone H4 gene. This probe hybridized to from five to more than ten fragments when N2 DNA was digested with various restriction enzymes, and the pattern of fragments was complex, with no indication of a tandem arrangement. Probes specific for each of the other four sea urchin histone genes gave similarly complex patterns on Southern hybridizations and it was not possible to deduce a simple map representing C. gene arrangement from multiple digestions of genomic DNA with combinations of enzymes. More detailed analysis of three phages carrying cloned histone genes confirmed the non-tandem arrangement. Histone genes were found to be present on these phages in clusters, each cluster containing at least one copy of each of the five histone genes. Two of the phages had two such clusters and one a single one, and there was no evidence of repetition in the location of restriction sites through or between the clusters. We are presently studying the remaining 19 phages to identify the arrangement of the genes on them and to correlate each with bands on a Southern hybridization of genomic DNA, our goal at this stage being to clone all of the C. genes. In its non-tandem, clustered arrangement of histone genes, C. sely resembles higher vertebrates than invertebrates such as sea urchin and Drosophila that have been most extensively studied to date.