Cloning and expression of protein tyrosine kinases in the medicinal leech

Some non-receptor protein tyrosine kinases (PTKs) are thought to play an important role in axonogenesis. I have partially cloned and sequenced two such PTKs found in Hirudo medicinalis : focal adhesion kinase (FAK) and Abelson kinase (Abl). Comparative analysis of the protein sequences of these two kinases reveal that they are closer in homology to vertebrate species than to other invertebrates, such as insects. Whole-mount in situ hybridization (WISH) showed that leech FAK mRNA is strongly expressed in the ganglia of the central nervous system and nephridia, as well as potential expression in the bilateral Comb cells. Leech Abl mRNA is strongly expressed in the ganglia and nephridia across all trials, while some WISH trials show expression in the bilateral heart tubes, Comb cells, as well as sensilla clusters. Attempts to knock down expression of Abl have thus far been inconclusive.