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Trypsin is an important serine protease that is considered to be involved in digestion of protein in teleost fish. Nevertheless, studies on trypsin/trypsinogen in fish embryos are very limited. In this study, the trypsinogen of turbot ( Scophthalmus maximus ) ( tTG ) was identified and the expression patterns and activity of trypsinogen/trypsin were investigated. The results showed that the tTG mRNA was evenly distributed in the oocytes and was also expressed along the yolk periphery in early embryos. At later embryo stages and 1 days after hatching (dph), the tTG mRNA concentrated at the alimentary tract and head. Quantitative expression analysis showed that the tTG transcripts decreased after fertilization until the gastrula stage, then increased with the embryo and larvae development. This result was also confirmed by the specific activity analysis of trypsin and in-situ-hybridization (ISH). All of the results indicated that tTG in early embryo stages was maternally derived and expressed by itself after gastrula stages. Additionally, location of tTG mRNA in embryos and larvae was investigated; we considered that trypsin may have multiple functions during the embryo development process. Based on our results regarding trypsinogen in embryos and early development, we concluded that the trypsin/trypsinogen in turbot embryos was inherited from a maternal source and we suggested that trypsin in early development has multiple functions in the process of development. [ABSTRACT FROM AUTHOR]

Abstract: An enzyme was purified from the pyloric caecum of tambaqui (Colossoma macropomum) through heat treatment, ammonium sulfate fractionation, Sephadex® G-75 and p-aminobenzamidine–agarose affinity chromatography. The enzyme had a molecular mass of 23.9kDa, NH2-terminal amino acid sequence of IVGGYECKAHSQPHVSLNI and substrate specificity for arginine at P1, efficiently hydrolizing substrates with leucine and lysine at P2 and serine and arginine at P1′. Using the substrate z-FR-MCA, the enzyme exhibited greatest activity at pH 9.0 and 50°C, whereas, with BAPNA activity was higher in a pH range of 7.5–11.5 and at 70°C. Moreover, the enzyme maintained ca. 60% of its activity after incubated for 3h at 60°C. The enzymatic activity significantly decreased in the presence of TLCK, benzamidine (trypsin inhibitors) and PMSF (serine protease inhibitor). This source of trypsin may be an attractive alternative for the detergent and food industry. [Copyright &y& Elsevier]

Trypsin activity is usually measured using synthetic substrates, principally amide and ester derivatives of the amino acids lysine or arginine. The aim of this study was to compare trypsin activity measurements done with two assays using amide substrates and two assays using ester substrates. The activity of purified commercial enzyme extracts (bovine and Atlantic cod, Gadus morhua) were measured as was the activity in animal tissues (mice and Atlantic cod) at 5, 15, 25, and 35°C. The results clearly showed the potential impact of the substrate choice on the results when comparing different taxonomic groups at different temperatures. The sensitivity, the measurement reproducibility and even the thermal sensitivity of the enzyme varies according to the assay used. [ABSTRACT FROM AUTHOR]

Hierarchies readily appear when rearing flounders through metamorphosis in space-limited conditions. In this experiment, subordinate fish were stressed, as suggested by their elevated cortisol level compared to dominant fish. Subordinate fish, although of smaller size than the dominant fish, showed no suppressed digestive capacity. By separating the two hierarchical groups into different tanks at low density, the cortisol level of the subordinate fish substantially decreased. The removal of the stressor also resulted in an increase in digestive function and improved coloration. Also, compensatory growth in length but not in weight was observed in the subordinate group, suggesting that the subordinate fish devoted their energy to increase their length. These results imply that the climax of flounder metamorphosis (i.e. the settlement stage) is a highly sensitive period, where social interactions may induce high levels of stress. However, Japanese flounder early juveniles prove to have a high recovery capacity from stress and show to allocate energy preferentially to growth in length. This seems to be an adaptation to diminish the probability of death by predation. [ABSTRACT FROM AUTHOR]

The effect of change in feed and physical manipulation on the digestive system of white shrimp Penaeus vannamei (Boone, 1931) was examined for proteases secreted by the digestive gland and excreted in feces. Organisms were fed a commercial feed containing 45% protein and separated into two groups. One group served as the control and the other was physically manipulated weekly. Each group was subdivided into two groups, establishing four experimental subgroups, 50% of the organisms in each group used as controls and the others subjected to a change in feed by shifting from a 45% protein feed to a 35% protein feed from different brands to induce alimentary stress. Organisms were individually maintained and feces collected and analyzed on a daily basis for 2 months. Trypsin and chymotrypsin activities decreased in feces and mid-gut gland extracts of organisms fed the 35% protein feed and those physically manipulated during weighting. Two-way ANOVA demonstrated a greater effect of physical manipulation on trypsin and chymotrypsin activities than change in feed. One-way ANOVA demonstrated differences between the two periods analyzed (before and after the beginning of stressors). Composition of proteases in the mid-gut gland and feces were identical, as observed by S-SDS PAGE. Studies of enzyme activities in feces may be helpful, when studying organisms of short digestion periods where very active enzymes and low-efficiency digestion are expected, as in the case of decapods. [Copyright &y& Elsevier]