Influence of season, environment and feeding habits on the enzymatic activity of peptidase and β-glucosidase in the gastrointestinal tract of two Siluriformes fishes (Teleostei)

Abstract

ABSTRACT. The enzymatic activities involved in the digestion of proteins and carbohydrates were compared among three organs of the digestive track of two Siluriformes fish species, and between two areas: a reservoir, and an area downriver of it. Our aim was to test the hypothesis that the digestive organs of species with varied feeding habits have different enzymatic activities, and that the enzymatic activity differs among seasons and environmental conditions. The iliophagous/herbivorous species Hypostomus auroguttatus Kner, 1854 had higher trypsin-like, chymotrypsin-like peptidase and ␤-glucosidase activity in the intestine when compared with the omnivorous species Pimelodus maculatus Lacepède, 1803, whereas the latter had more hepatic trypsin-like activity than the former. The peak of activity of the three enzymes in H. auroguttatus was recorded in the winter and spring. On the other hand, P. maculatus tended to have the more prominent peptidase and ␤-glucosidase activity in the summer, and the smallest in the winter. The intestine of H. auroguttatus had higher enzymatic (trypsin, chymotrypsin and ␤-glucosidase) activity than the stomach and the liver.For P. maculatus, the highest ␤-glucosidase activity was found in the liver. The enzymatic activity of H. aurogutattus did not differ between lotic and lentic systems, whereas P. maculatus had comparatively higher stomach and hepatic trypsin levels and hepatic chymotrypsin-like activities in the reservoir than down in the river. These findings indicate that, in H. auroguttatus, most digestive activity occurs in the intestine, which is long and adapted for the digestion of bottom-river vegetable matter and detritus. The seasons and the type of the system (lentic vs. lotic) seem to affect the enzymatic activity for these two species differently, a likely consequence of their different lifestyles.

Composition of gastrointestinal content, protease and lipase activities in summer and winter of four freshwater siluriforms (Teleostei: Actinopterygii) with two different feeding habits

“…In the present study, the activities of digestive enzymes in P. maculatus varied with the season, with some having higher activity in the summer and others in the winter. Overall, H. commersoni and L. anus presented higher enzyme activity in the intestine than in the stomach, as observed by Duarte et al (2013) in H. auroguttatus. This is in agreement with the fact the stomach is an accessory respiratory organ in H. commersoni and in species of Loricariichthys, and consequently the role of the stomach in digestion is very small (Silva et al 1997, Podkowa andGoniakoska-Witalinska 2003).…”

“…The higher activity of trypsin and chymotrypsin in the posterior intestine of P. maculatus, L. anus and H. commersoni, in spite of the lower protein content of this portion in both seasons could be related to an increase of the activities of digestive enzymes to completely utilize the low concentrations of protein in the food. Analysis of the digestive enzyme activities in 11 species distributed in three trophic categories (Chakrabarti et al 1995) and four phylogenetically related species with two feeding habits (Chan et al 2004) and the studies of López-Vázques et al (2009) and Duarte et al (2013) also led to the same conclusion.…”

“…The enzymatic activity may also vary according to the specific characteristics of each species in the production of digestive enzymes. Duarte et al (2013) found increased trypsin, chymotrypsin, and β-glucosidase activities in the winter and spring for the detritivorous/herbivorous Hypostomus auroguttatus Kner, 1854 (Loricariidae), and increased peptidase and β-glucosidase activities during the summer in P. maculatus. The authors associated this variability with the food availability in H. auroguttatus and the reproductive migration that takes place at this time in P. maculatus.…”

“…The aim of this study was to determine the composition of gastrointestinal content and protease and lipase activities in summer and winter of two omnivorous species, R. quelen and P. maculatus, and of two detritivorous species, L. anus and H. commersoni. Different seasons were chosen because food availability and the activities of digestive enzymes can change with the season (Duarte et al 2013). Based on the results, it was also evaluated if there are relationships between digestive enzyme activity, centesimal composition of gastrointestinal content and feeding habits.…”

Gram-negative intestinal indigenous microbiota from two Siluriform fishes in a tropical reservoir

“…The armored catfish ( Hypostomus auroguttatus, Kner 1854) is a benthic iliophagous/herbivorous species with ventral lips (oral papillae) adhering to the river bottom and feeding by grasping the plant organic matter and “microalgae film” associated to rocky substrate ( Fugi and Hahn, 1991 ). Such characteristics are probably functionally related to the fact that individuals in this species have one of the largest intestines among the teleosteans, with some individuals of this species having intestines reaching about fifteen times their individual length ( Duarte et al , 2013 ). This suggests the occurrence of a prolonged digestive process ( Nelson, 2002 ) that might depend on the presence of microbiota.…”