Comparative characterization of protease activity in cultured spotted rose snapper juveniles (Lutjanus guttatus)

Abstract

Partial characterizations of digestive proteases were studied in three life stages of spotted rose snapper: early (EJ), middle (MJ) and late juvenile (LJ) with corresponding average weights of 21.3 ± 2.6 g (3 months after hatching, MAH), 190 ± 4.4 g (7 MAH), and 400 ± 11.5 g (12 MAH). At sampling points, the digestive tract was dissected into the stomach (St), pyloric caeca (PC), and the intestine in three sections (proximal (PI), middle (MI) and distal intestine (DI)). The effect of pH and temperature and specific inhibitors were evaluated for acid and alkaline proteases. Total acid and alkaline protease activity showed a tendency to increase with juvenile life stage of fish while trypsin activity decreased. Differences were found in acid and alkaline protease activities at different pH and temperatures during juvenile stages. Pepstatin A inhibited total activity in the stomach extract in all juvenile stages. Activity in total alkaline protease inhibition was significantly higher in EJ using TLCK, PMSF, SBTI, Phen and Ovo than in MJ and LJ, while no significant differences were found with TPCK inhibition. Therefore increases in protease activities with fish growth through juvenile stages in which a substitution or diversification in the type of alkaline enzymes exist. These results lead a better comprehension of changes in digestive potential of Lutjanidae fish.

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

“…The high activity of acid proteases found in Lutjanus peru juveniles concerning alkaline proteases highlights the carnivorous tendency of the species, as reported in other Lutjanidae species such as yellow snapper L. argentiventris (Peters, 1869), Pacific dog snapper L. novemfasciatus (Gill, 1862) and L. guttatus (Alarcón et al 2001, Peña et al 2015. The optimal activity found for acid proteases was between 2 and 3 from three bands with acid activity (Rf of 0.19, 0.63, and 077), all identified as aspartic peptidases, such as pepsin-like.…”

“…The optimum temperature of acid proteases in L. peru was found at 30 and 40°C, while reports in L. guttatus registered optimum temperature for pepsin activity at 45°C during the juvenile stage (Peña et al 2015). Consequently, the broad range of temperature optimum found in L. peru pepsin is related to differences in structural properties among the three isoforms found in the present study (Fig.…”

“…4). Reports in L. guttatus showed optimum temperatures for trypsin between 50 and 60°C (Peña et al 2015), while brown stripe red snapper Lutjanus vitta (Quoy & Gaimard, 1824) shows a peak for trypsin activity at 60°C (Khantaphant & Benjakul 2010). Therefore, the high activity of trypsin isoforms at 30°C gives digestive advantages at the environmental condition as previously mentioned comparing with the other Lutjanidae species.…”

“…Most fish species with stomachs have two to four isoforms of pepsins which show an optimum activity between pH 2.0 to 3.5 (Klomklao 2008, Zhao et al 2011. Previous studies in L. gutattus showed pH pepsin optimum between 2 and 3, with two bands (Rf of 0.72 and 0.79) (Peña et al 2015(Peña et al , 2017. Some fish species shows a single pepsin band, such as C. undecimalis (Concha-Frías et al 2016) probatocephalus (Merino-Contreras et al 2018).…”

“…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.…”