These data establish that Drosophila indeed possesses a conserved p38 MAP kinase signaling pathway. The role of the D-p38 MAP kinases in the regulation of insect immunity was examined. The expression patterns of the protein kinases were examined in the developing embryo to gain information about the possible functional relationship among the MAPK and MKK isoforms. The two D-p38 genes exhibit different embryonic expression patterns. The D-p38a mRNA expression is predominantly at the preblastoderm stage, indicating a high level of maternal deposition.
Zygotic expression is to low to be detected during most of the embryonic development.
Northern analysis, however, demonstrates the presence of low mRNA levels throughout development. At stage 16, there is a low level of staining in the posterior region, which may correspond to the developing hindgut. The preblastoderm staining indicates that D-p38a may participate in early embryonic development. The D-p38b gene is expressed throughout embryonic development. There is a high level of maternal deposition, and at later stages, zygotic expression is present in most of the tissues.