Organogenesis of exocrine pancreas in sharpsnout sea bream (Diplodus puntazzo) larvae: characterization of trypsin expression
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The ontogeny and differentiation stages of digestive systems related with trypsin expression in larvae of sharpsnout sea bream, Diplodus puntazzo, were investigated from hatching to 40 DAH (days after hatching), and total lengths and weights of larvae were determined. Histologic and enzymatic techniques were used to explain the functional development of the pancreas including trypsin activity. The pancreas was identified as a compact structure located in the region slightly posterior to the liver. At 3 DAH, first anus and then mouth opened. Incipient pancreas secretion polyhedral cells could be first observed as zymogen granules. During larval metamorphosis, the pancreas became diffuse, spreading throughout the mesentery in proximity to the stomach, the anterior intestine and the pyloric caeca. The specific activity of trypsin (42.54 ± 6.8 mU/mg protein−1) was found as early as after hatching at larvae size of 2.87 ± 0.34 mm at 0 DAH. Activity further increased until 10 DAH, especially after exogenous feeding. The highest trypsin activity was detected at 25 DAH as 119.26 ± 11.6 mU/mg protein−1. It is concluded that exocrine pancreas organogenesis is the main critical step in the development of digestive system that results in zymogen granules accumulation and increased trypsin activity.
KeywordsDiplodus puntazzo Exocrine pancreas Histology Trypsin Ontogeny Growth
The authors would like to express our sincere gratitude to Assoc. Prof. Dr. Hakan POSTACI for the excellent cooperation for histological analysis and also the staff of the Teknomar Sea Fish Broodstock Centre where the experiments were conducted (Akuvatur Mediterranean Sea Foods, Izmir, TURKEY) for their most efficient technical assistance.
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