Temporal transcription of two antennapedia class homeobox genes in the marine copepod Calanus helgolandicus.

DNA sequence information has been obtained for 2 genes implicated in playing critical roles in copepod development. The first ( Cal-antp) was obtained by screening a Calanus helgolandicus genomic library. It shows homology to Antennapedia homeobox genes from a number of organisms including the centipede (76.8% over 250 bp) and the brine shrimp (75.5% over 220 bp). A second sequence (Hox 12) was obtained through reverse transcription polymerase chain reaction (PCR) of a solid-phase cDNA library constructed from Calanus eggs, and subsequent inverse PCR using a genomic DNA template. The Hox 12 sequence is homologous to the Antennapedia class of genes and shares homology with the chicken HoxB3 gene (71% over 187 bp) and with the fruit fly Sex Combs Reduced ( Scr) homeotic gene (66% identity over 223 bp). Using sequence data from Cal-Antp and Hox 12, specific primers were designed to investigate the temporal expression of these genes by PCR analysis of 10 stage-specific cDNA libraries.