Applying different hybridization techniques we could confirm existence and transcription of sequences related to the proto-oncogene c-src in freshwater and marine species of sponges, the most primitive metazoan animals. By using the in situ hybridization technique, we were able to demonstrate for the first time that the cell-type-specific expression, characteristic for c-src related genes in higher vertebrates, is even realized in a freshwater sponge (Spongilla lacustris). The highest amount of c-src related transcripts was found in the omnipotent stem cells, the archaeocytes, and in the cells forming the inner epithelia, the endopinacocytes, which probably are involved in signal transduction.

Related Articles