Two engrailed-related genes in the cockroach: cloning, phylogenetic analysis, expression and isolation of splice variants.

engrailed-related genes have been isolated in numerous taxa. Within the insects, some species have a single engrailed-related gene whilst others have two copies, raising the question of when and how often gene duplications have occurred. Here we report the cloning, in the cockroach Periplaneta americana, of two engrailed-related genes Pa-en1 and Pa-en2. By comparing conserved domains and by carrying out a phylogenetic analysis, we conclude that these two genes are likely to be the product of a recent duplication in the cockroach lineage. Pa-en1 and Pa-en2 are co-expressed during early embryogenesis and their segmental pattern of expression appears in an anterior-posterior progression. We have also isolated potential splice variants of Pa-en2 which lack some regulatory domains. The roles these splice variants may play in regulating developmental processes are discussed.