TRANSIENT EXPRESSION OF A NOVEL SERINE-PROTEASE IN THE ECTODERM OF THE ASCIDIAN HERDMANIA-MOMUS DURING DEVELOPMENT

We have studied gene expression during ascidian embryonic development using the technique of differential display and isolated partial cDNA sequences of 12 genes. Developmental regulation of these genes has bee n confirmed by northern hybridization analysis. Further cDNA cloning a nd sequence analysis of an mRNA that is present during gastrulation, n eurulation and tailbud formation reveals that it encodes a novel serin e protease containing a single kringle motif and catalytic domain. The spatial expression of this gene, designated Hmserp1, is restricted to precursor cells of the epidermis. The structure and expression of Hms ery1 is discussed in relation to possible functions during development .