The gene Polycomb is responsible for the elaboration and maintenance of the expression pattern of the homeotic genes during development of Drosophila. It encodes a nuclear protein which is associated with the chromatin together with other proteins of the Polycomb group. The mechanism of gene regulation caused by Polycomb seems to be similar to that of the modifier genes of position effect variegation which also encode structural proteins of the heterochromatin. One of these proteins is HP1 which shares with Polycomb a region of similarity at the amino terminus called the Chromatin Organisation Modifier domain (chromo domain). The particular function of the chromo domain is not yet understood, but it seems to be important for protein-protein interactions in chromatin associated complexes. Furthermore, chromobox containing genes were found in several animal and plant species. C. elegans contains at least one chromobox containing gene (cmO8
h7 ),which is located on the third chromosome between
unc116 and
ceh16 .Length (304 aa) and structure (the chromo domain located near the amino terminus) of the putative C. elegans chromo domain protein are similar to those of the chromo domain containing proteins of other species (cf. fig.). Low stringency hybridization with chromobox containing probes revealed evidence for the existence of other chromobox containing genes within the genome of C. elegans. We are currently studying the expression pattern of cmO8
h7 .Therefore, we are rising antibodies against the chromo domain and other regions with E. coli expressed proteins from cmO8
h7 .Furthermore, we started to do different -gal fusion constructs, containing 5kb or 1Okb of the upstream sequences of the chromobox containing gene, for the injection into the germ line of C. elegans.