ISOLATION OF THE CDNA AND CHARACTERIZATION OF MESSENGER-RNA EXPRESSION OF RIBOSOMAL-PROTEIN S19 FROM THE SOFT-SHELL CLAM, MYA ARENARIA

Ribosomal proteins contribute to the regulation and activity of riboso mes, and hence, the translational activity of the cell. Aberrant expre ssion of ribosomal proteins has been linked to certain pathological co nditions such as neoplasms. We have isolated and characterized a cDNA for the ribosomal protein (rp) S19 from a marine bivalve, the soft-she ll clam (Mya arenaria), and we have examined its pattern of mRNA expre ssion in the ovary and testis. The S19 cDNA contains a 450 nucleotide (nt) open reading frame (ORF), flanked by 89 nt and 26 nt of 5' and 3' untranslated regions, respectively. Probes synthesized from the S19 c DNA recognize a single transcript of approximately 550 nt in four diff erent tissues. The predicted amino acid sequence from the ORF exhibits 58% identity with human and rat S19. Southern analysis of genomic DNA suggests that M. arenaria may have multiple copies of S19, a feature that is more similar to vertebrate than invertebrate rp genes. Express ion of S19 mRNA in both ovary and testis was elevated throughout gamet ogenesis until after spawning, when a decrease in S19 message was obse rved. A comparison of S19 mRNA levels in post-spawn animals revealed a trend of elevated expression in ovaries and testes affected by a gona dal neoplasm, indicating that S19 may be a useful molecular marker for the pathological condition. (C) 1997 Elsevier Science B.V.