Partial characterization of digestive proteases in juveniles of Microphis brachyurus (short-tailed pipefish) (Syngnathiformes: Syngnathidae)

Abstract

Short-tailed pipe fish (Microphis brachyurus) is a freshwater organism with high economic potential for the aquarium hobby, so it is necessary to implement methods to promote its culture through studies of digestive physiology. General activities of acid and alkaline proteases were evaluated, as well as the effect of pH, temperature and inhibitors. The optimal pH of stomach proteases was 2, while the optimal pH of intestinal proteases was 10. Optimal temperature for the acidic proteases was 35 ºC, while for alkaline proteases it was 45 ºC. Thermal stability showed high resistance at 35 ºC for both acid and alkaline proteases (above 100% residual activity). Acid proteases are resistant at pH 2 (50% of residual activity), meanwhile alkaline proteases were highly resistant at pH 10 (90% of residual activity). Acid proteases were inhibited by 80% with pepstatin A and alkaline proteases were inhibited with TLCK and TPCK for trypsin (75%) and chymotrypsin (80%), respectively. Finally, metallo-proteases were 75% partially inhibited some serine proteases by 75% with EDTA. In conclusion, M. brachyurus has a good digestive capacity, since they can degrade a wide variety of proteins due to their greater proteolytic activity.

Partial characterization of digestive proteases in Pacific red snapper Lutjanus peru Nichols & Murphy, 1922 (Perciformes: Lutjanidae)

“…Therefore, studies concerning protein digestive physiology are necessary to develop a species-specific diet and determine the amount and type of ingredients that could be included. In this way, the appearance of digestive enzymes has been related to various physiological characteristics (feeding habits) and nutritional characteristics (requirements) in many species of marine fish, such as spotted rose snapper Lutjanus guttatus (Steindachner, 1869), thicklip grey mullet Chelon labrosus (Risso, 1827), common snook Centropomus undecimalis (Bloch, 1792) and sheepshead Archosargus probatocephalus (Walbaum, 1792) (Peña et al 2015, Concha-Frias et al 2016, Pujante et al 2017, Merino-Contreras et al 2018, as well as some freshwater fish, such as tropical gar Atractosteus tropicus Gill, 1863, Mayan cichlid Mayaheros urophthalmus (Günther, 1862), tree-spot cichlid Cichlasoma trimaculatum (Günther, 1867), green cichlid Cichlasoma beani (=Mayaheros beani) (Jordan, 1889) and short-tailed pipefish Microphis brachyurus (Bleeker, 1854) (Cuenca-Soria et al 2014, Toledo-Solís et al 2015, Martínez-Cárdenas et al 2020. Thus, the objective of the present work was to partially characterize the digestive proteases in the L. peru using biochemical and electrophoretic techniques.…”