Biochemical Composition and Digestive Enzyme Activity of Anguilla bicolor McClelland 1844 on Reproductive Phase

Biochemical compositions and digestive enzyme activities during the embryonic development of prawn, Macrobrachium rosenbergii

This study was performed to determine the effect of starvation and delayed feeding on activities of digestive enzymes and alkaline phosphatase (ALP) of larval red swamp crayfish (Procambarus clarkii), so as to reveal the tolerance to prolonged starvation and the recovery of digestive enzymes after delayed feeding in larval and juvenile P. clarkii. In the control group, activities of trypsin and ALP increased significantly (p < .05) with day-age and then kept constant at 24 days after hatching (DAH) and 10 DAH, respectively, whereas the activities of amylase and pepsin increased firstly then decreased with day-age, and the activity of lipase increased firstly then decreased and then increased again during the development period of juvenile P. clarkii (1–31 DAH). In the group with continuous starvation (CS), activities of pepsin and lipase both decreased (p < .05) after fasting, and the activities of pepsin, lipase and trypsin in the groups with delayed feeding all increased (p < .05) and recover to the levels of the control group after food supply. However, the activity of amylase increased (p < .05) in the CS group, and it decreased to normal level after food supply. The ALP activity did not significantly (p > .05) vary after starvation, whereas it decreased in the groups with delayed feeding after 1 day of food supply, and then increased back to the level similar with the control group. Results from this study could provide information for diet preparation and feeding regime in larval and juvenile red swamp crayfish culture.

Surface chemistry of graphene tailoring the activity of digestive enzymes by modulating interfacial molecular interactions

Comparative aspects of circulating erythrocytes in the trophic and reproductive phases of European eel. Ultrastructure and cytochemistry.

Cobia Rachycentron canadum is an economically important fish and is cultured throughout southern China and other part of the world. However, the knowledge of metabolism and nutritional requirements of cobia embryos remains limited. This study investigated changes of the biochemical composition, as well as the activities of related digestive and antioxidant enzymes during the development of both eggs and yolk-sac larvae of the cobia (Rachycentron canadum). The results showed that egg mass at the fertilized stage increased gradually to the blastula stage and showed a significant increase at the segmentation stage and a significant decrease at the larval period. The main components of embryos and larvae were carbohydrates, lipids and proteins. Protein and lipid contents decreased at the blastula stage, increased significantly at the segmentation stage and then decreased thereafter. Carbohydrate contents decreased significantly during the development. Enzymatic activities showed a progressive increase from the embryo to the yolk-sac larval stage. The activities of pepsin and trypsin increased significantly during the development. Amylase activity remained low before the blastula stage and increased rapidly thereafter. Lipase showed an ‘increase–stable–increase’ tendency. Changes of digestive enzyme activities indicated the dynamics of the biochemical composition. Activities of glutathione peroxidase, catalase and superoxide dismutase significantly increased during embryonic and yolk-sac stages, and malondialdehyde contents followed the same trend. The results of the current research provide vital information to enhance yolk exploitation with a specific focus on organogenesis. Moreover, considerable knowledge on the embryonic development of the cobia is presented.

The effect of water temperature on gut mass and digestive enzyme activity in sea cucumber Apostichopus japonicus, including relative gut mass (RGM), amylase, lipase, pepsin and trypsin activities were studied at temperatures of 7, 14, 21, and 28°C over a period of 40 days. Results show that RGM significantly decreased after 40 days at 21°C and markedly decreased over the whole experiment period at 28°C; however, no significant effect of duration was observed at 7 or 14°C. At 14°C, trypsin activity significantly decreased over 10 and 20 days, then increased; amylase and trypsin activity significantly decreased after 40 days at 28°C. However, no significant effect of duration was found on amylase, pepsin or trypsin activities in the other temperature treatment groups. At 28°C, lipase activity peaked in 20 days and then markedly decreased to a minimum at the end of the experiment. On the other hand, pepsin activity at 28°C continuously increased over the whole experimental period. Principle component analysis showed that sea cucumbers on day 40 in the 21°C group and in the previous 20 days in the 28°C group were in the prophase of aestivation. At 28°C, sea cucumbers aestivated at 30–40 days after the start of the experiment. It is concluded that the effect of temperature on the digestion of A. japonicus is comparatively weak within a specific range of water temperatures and aestivation behavior is accompanied by significant changes in RGM and digestive enzyme activities.

Nutritional effects on ingestion rate, digestive enzyme activity, growth, and biochemical composition of Hyas araneus L. (Decapoda: Majidae) larvae

In order to evaluate the interplay of nutritional status and the digestive capacity, immune function, and gut microbiota in the oriental river prawn Macrobrachium nipponense, a 14-day starvation trial was conducted to detect the effects of starvation on the activities of digestive enzymes and immune enzymes and the structure of prawn gut microbiota. The adult prawns were randomly assigned to a control group (F group) and starvation group (S group) with three replicates. The F group was normally fed with commercial diet, and the S group was starved for 14 days. The result showed that digestive enzyme activities of trypsin and lipase in the hepatopancreas of the S group were significantly lower than those of the F group after 4 d of starvation ( P &lt; 0.05 ), while the activity of amylase significantly increased after 14 d of starvation ( P &lt; 0.05 ). Moreover, the results of the histological analysis of prawn gut showed that both the height of epithelial cells and microvilli of intestine in the S group were obviously decreased than those in the F group ( P &lt; 0.05 ) after 14 d of starvation. The activities of immune-related enzymes including superoxide dismutase, catalase, and acid phosphatase in the hepatopancreas of the S group significantly decreased after 4 d of starvation, and lysozyme activity of the F group was lower than that of the S group after 7 d of starvation ( P &lt; 0.05 ). In addition, the results of Illumina high-throughput sequencing showed that a total of 14,285 OTUs were obtained and classified into 30 phyla, among which Actinobacteria and Proteobacteria were the predominant microflora in the intestinal microbial communities of both groups. However, the relative abundance of opportunistic pathogens was significantly increased in the S group, while the relative abundance of beneficial bacterium was decreased ( P &lt; 0.05 ). The bacterial richness with the Chao estimator was significantly higher in the F group than in the S group ( P &lt; 0.05 ). Both the results of principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS) demonstrated that the intestinal microbiota of the F group was separate from those of the S group. The result of functional prediction of the metabolic pathways showed that the intestinal microbiota was enriched in the KEGG pathways of amino acid, carbohydrate, fatty acid, and lipid biosynthesis and degradation at level 2. This result implied that the microbiota of shrimp gut decreased nutrition metabolism under the stress of starvation. Meanwhile, comparing to the F group, the immune-related pathway of enterobacterial common antigen biosynthesis was markedly reduced in the S group ( P &lt; 0.05 ). The result of redundancy analysis (RDA) further confirmed that the activities of digestive and immune enzymes were correlated with the microbial community structure. Finally, the structural equation modeling highlighted that changes in the activities of digestive and immune enzymes were directly related to the gut bacterial community and notably affected prawn growth.

To explore the feasibility of land-based farming on mackerel tuna (Euthynnus affinis), the changes of antioxidant, immune and digestive enzyme activities of wild caught and indoor cultured juvenile mackerel tuna were evaluated. The activities of total superoxide dismutase, catalase, peroxidase and alkaline phosphatase in the liver of the wild group were significantly higher than those cultured under captivity. The total superoxide dismutase and peroxidase activities in the indoor cultured group were significantly increased in the head kidney, and the MDA content was significantly increased. The activities of lysozyme in the liver and head kidney, the activities of amylase, lipase and trypsin activities in the intestine were significantly increased in the indoor cultured group. The pepsin activity in the stomach was significantly reduced. The land-based farming increased the digestive enzyme activity compared to the wild caught group. The mode of land-based farming is suitable for growth and fattening of young fish, but it leads to inhibition of antioxidant capacity and increase in immune enzyme activity. This study adds knowledge of our understanding on the physiological response of mackerel tuna and improves future farming practice of this species in an indoor condition.

Periphyton grown on sugarcane bundles was analyzed for major digestive enzymes in order to quantify their possible exogenous digestive enzyme contribution to the grazing fish. The proximate and taxonomic composition of constituent planktonic organisms of periphyton was compared with that of free plankton. Further, the activity of major digestive enzymes in the extracts of periphyton and free plankton was also compared. The proximate composition analysis revealed periphyton to contain more (P < 0.05) crude protein, ash, crude fibre and NFE (nitrogen-free extract) with lesser moisture content as compared to plankton. The species composition of periphyton from bagasse revealed that plankton belonging to Chlorophyceae were dominant (25.3 %), followed by Cyanophyceae (19.7 %), Bacillariophyceae (16.9 %), Conjugatophyceae (8.4 %), Desmidaceae (4.2 %), Euglenophyceae (5.6 %), Ulvophyceae (4.2 %), Dinophyceae (1.4 %), Xanthophyeae (1.4 %), Florideophyceae (1.4 %), Trebouxiophyceae (1.4 %) and zooplankton (10 %). Free plankton consisted of Chlorophyceae (24.2 %), Cyanophyceae (15.1 %), Bacillariophyceae (9.1 %), Conjugatophyceae (6.1 %), Coscinodiscophyceae (3 %), Trebouxiophyceae (3 %) and zooplankton (39.4 %). The activity of majority of digestive protease and amylase was higher in plankton and that of chymotrypsin was higher in periphyton, while lipase activity did not show any difference between plankton and periphyton. The study indicates that periphyton being a natural food is nutritionally superior to free plankton and can contribute digestive enzymes to the grazing fish, in addition to the nutrients.

A study was performed to investigate the effect of weaning at 4 weeks of age on the activity of digestive enzymes in the stomach and pancreatic tissue and in digesta from 3 days prior to weaning to 9 days postweaning in 64 piglets. In stomach tissue the activity of pepsin and gastric lipase was determined. Pepsin activity declined abruptly after weaning but 5 days postweaning the weaning level was regained and in the gastric contents no change in pepsin activity was observed. Weaning did not influence the activity of gastric lipase. The activity of eight enzymes and a cofactor was measured in pancreatic tissue. The effect of weaning on the enzyme activity was highly significant for all enzymes except elastase. The activity of all enzymes remained at the weaning level during day 1–2 postweaning followed by a reduction of the activity. The activity of trypsin, carboxypeptidase A, amylase and lipase exhibited minimum activity 5 days postweaning. Trypsin activity increased to the preweaning level on day 7–9 whereas the activity of the others increased but did not reach the preweaning level. The activity of chymotrypsin, carboxypeptidase B and carboxyl ester hydrolase decreased during the entire experimental period. In digesta no effect of weaning was observed on the activity of amylase and trypsin. The activity of chymotrypsin was reduced after weaning in the proximal third of the small intestine and lipase and carboxyl ester hydrolase activity was reduced in the middle and distal parts of the small intestine after weaning. The present study shows that the activities of the digestive enzymes in the pancreatic tissue are affected by weaning. Even though the pancreatic secretion cannot be judged from these results they show that the enzymes respond differently to weaning. In general the activity of the digestive enzymes in pancreatic tissue is low on day 5 postweaning which in interaction with other factors may increase the risk of developing postweaning diarrhoea.

Avian herbivores face the exceptional challenge of digesting recalcitrant plant material while under the selective pressure to reduce gut mass as an adaptation for flight. One mechanism by which avian herbivores may overcome this challenge is to maintain high activities of intestinal enzymes that facilitate the digestion and absorption of nutrients. However, previous studies in herbivorous animals provide equivocal evidence as to how activities of digestive enzymes may be adapted to herbivorous diets. For example, “rate-maximizing” herbivores generally exhibit rapid digesta transit times and high activities of digestive enzymes. Conversely, “yield-maximizing” herbivores utilize long gut retention times and express lower activities of digestive enzymes. Here, we investigated the activities of digestive enzymes (maltase, sucrase, aminopeptidase-N) in the guts of herbivorous grouse (Aves: Tetraoninae) and compared them to activities measured in several other avian species. We found that several grouse species exhibit activities of enzymes that are dramatically lower than those measured in other birds. We propose that grouse may use a “yield-maximizing” strategy of digestion, which is characterized by relatively long gut retention times and generally lower enzyme activities. These low activities of intestinal digestive enzyme could have ecological and evolutionary consequences, as grouse regularly consume plants with compounds known to inhibit digestive enzymes. However, more comprehensive studies on passage rates, digestibility, and microbial contributions will be necessary to understand the full process of digestion in herbivorous birds.

Activity of digestive enzymes in yolk-sac larvae of Atlantic halibut ( Hippoglossus hippoglossus): indication of readiness for first feeding

The major anatomical divisions of the cerebellum of the European eel, i.e., corpus cerebelli, lobus vestibulolateralis, and valvula, were studied morphologically and morphometrically. There were differences in cerebellar cytoarchitecture and gross morphology in two stages of the eel life cycle, the trophic stage (yellow eel), and the reproductive stage (silver eel), which are characterized by different degrees of swimming activity. The principal differences between silver and yellow eels in the cytoarchitecture of the corpus cerebelli and the lobus vestibulolateralis were in distribution of Purkinje or Purkinje-like cells in the molecular layer, which is wider in silver eels, in part because of a decreased thickness of the granular cell layer. In the silver eel, the scattering of Purkinje cells was more evident in the lobus vestibulolateralis where the molecular layer is also thicker. The data indicate the transition from the yellow eel to the silver eel is characterized by a migration of granule cells from the ganglionic cell layer to the internal granular layer and by a further development of molecular layer components, e.g., parallel fibers, Purkinje-cell dendrites, etc. In contrast, the thickness of the granular layer and of the Purkinje cell layer, limited to the lower part of the valvula, decreased. There is also a slight increase of cerebellar volume in the silver eel. The volume of the lobus vestibulolateralis was constant. Hypertrophy of the valvula and eminentiae granulares is observed and is due to the migration of cells from the granular layer of the corpus cerebelli whose volume slightly decreases. Perhaps the lobus vestibulolateralis also contributes to the increased volume of eminentiae granulares. Our findings suggest that the cerebellum continues to develop during the passage from the trophic to the reproductive stage of the eel. The appearance of new afferents from the lateral line which becomes more visible in the silver eel probably completes cerebellar ontogeny.

The mid gut in insects is usually lined with a peritrophic membrane (PM), which protects it from microbial infections and physical contact with ingested food. Calcofluor is an optical brightener that has strong chitin-binding properties, which disrupt the chitin-protein structure of PM. In this study, we investigated the effects of calcofluor on the structure of the PM, activity of some common digestive enzymes and biological characteristics of the Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae). Twenty hours after feeding on a calcofluor-containing diet, the PM was completely eliminated. We recorded significant effects of calcofluor on the activity of digestive enzymes in the mid and hindguts of larvae. In both these regions of the gut, in particular, there were significant increases in the activity of α-amylase, α-galactosidase and trypsin. The activities of α-glucosidase and β-glucosidase in the midgut of treated larvae were lower than in the control, but were significantly higher in the hindgut of treated larvae. The larvae that fed on on calcofluor for 20 h, took longer to complete their larval and pupal stages, were lighter in weight and fewer reached maturity and laid fewer eggs. Results of this and previous studies highlight the crucial role of PM in enzyme recycling and digestion. PM disruption may negatively affect insect development on the one hand, by decreasing the efficiency of food digestion and, on the other, by increasing the costs associated with an increased enzyme demand and disrupted enzyme recycling mechanism.