Effects of dietary protein on the activity and mRNA level of trypsin in the midgut gland of the white shrimp Penaeus vannamei.

Protein food modulates the activity of proteases of the midgut gland of Penaeus vannamei. Shrimp fed with food containing 15, 30 and 50% protein exhibited differences in trypsin and chymotrypsin activity and trypsin mRNA levels. Shrimp fed with 30% protein showed higher trypsin and chymotrypsin activities than those fed 15 or 50% protein. An additional paralogue trypsin was observed with electrophoretic analysis in shrimp fed 30% protein. Shrimp fed 30% protein showed the highest trypsin to mRNA concentration, suggesting that trypsin genes expression is regulated transcriptionally.