Pepsinogen A and C genes in turbot (Scophthalmus maximus): characterization and expression in early development

We characterized the expression patterns of pepsinogen A (tPGA) and pepsinogen C (tPGC) in turbot (Scophthalmus maximus). Quantitative expression analysis showed that tPGC was preferentially expressed in early developmental stages, and that the tPGA mRNA expression level was higher in adult fish. Full-length cDNA constructs of tPGA and tPGC were 1307 bp (from which 377 amino acids were deduced); and 1430 bp (from which 385 amino acids were deduced), respectively. The deduced proteins of tPGA and tPGC possessed signal peptides of 17 amino acids and 20 amino acids respectively. The initial transcripts of tPGA and tPGC were detected at 22 days post hatching (dph), well after the formation of gastric glands (16 dph). This suggested that the morphologic development of gastric glands was not synchronous with their functional development. In addition, tPGA and tPGC mRNAs were also expressed in muscle and ovary at much lower levels than in stomach and esophagus. The distribution of tPGA and tPGC in the turbot was investigated using in-situ hybridization, and tPGA and tPGC were first detected in the esophagus and cardiac region of the stomach, and then throughout the stomach.