Effect of temperature on proteinase activities in intestinal chyme and mucosa of fish of different ecological groups

Effect of temperature on activities of proteinases in intestinal chyme and mucosa was studied in three fish species (pike-perch, zope, roach) belonging to different ecological groups by their nutrition type. There was revealed a significant difference of dependence of enzyme activities in chyme on temperature in the benthophage, roach (a higher level of relative activity in the range of lower temperatures and a wider zone of temperature optimum) as well as of values of apparent energy of activation of the protein hydrolysis process as compared with that in planktoand ichtyophages, zope and pike-perch, which indicates a significant effect of the enteral microbiota proteinases and of nutrition objects on characteristics of hydrolases functioning in fish intestine.     

Effect of temperature on proteinase activities of enteral microbiota and intestinal mucosa of fish of different ecological group

Effect of temperature on proteinases activities of enteral microbiota and of intestinal mucosa was studied in five fish species (roach Rutilus rutilus, crucian carp Carassius carassius, common perch Perca fluviatilis, pike-perch Zander lucioperca, and pike Esox lucius) belonging by the nutrition type to different ecological groups. Essential differences of temperature characteristics of proteinases of intestinal mucosa and of enteral microbiota are revealed in fish belonging by the nutrition type to different ecologic groups. The character of the t0-function of proteinases of intestinal mucosa and enteral microbiota by casein and hemoglobin as a rule is different. The highest values of relative proteinases activities for casein in the zone of low temperatures (38 and 45.3 % of the maximal activity) are found at study of proteinases of enteral microbiota in common perch and crucian carp. The latter indicates a significant adaptability of the enteral microbiota proteinases of common perch and crucial carp to functioning at low temperatures.     

The effect of temperature on chyme proteinase activities in perch Perca fluviatilis L. and roach Rutilus rutilus (L.)

The effect of temperature on the chyme proteinase activities of the perch Perca fluviatilis L. and the roach Rutilus rutilus (L.) was investigated. The two fish species showed different characters of temperature dependence and different values of activation energy for caseinolytic and hemoglobinolytic chyme proteinases. The perch was characterized by a higher level of relative proteinase activities and lower activation energy for protein hydrolysis at a temperature of 0–10°C than the roach.     

Effect of temperature on proteinase activites of enteral microbiota and intestinal mucosa of fish of different ecological groups

Effect of temperature on proteinases activities of enteral microbiota and of intestinal mucosa was studied in five fish species (roach Rutilus rutilus, crucian carp Carassius carassius, common perch Perca fluviatilis, pike-perch Zander lucioperca, and pike Esox lucius) belonging by the nutrition type to different ecological groups. Essential differences of temperature characteristics of proteinases of intestinal mucosa and of enteral microbiota are revealed in fish belonging to different ecological groups. The character of the t-function of proteinases of intestinal mucosa and enteral microbiota for casein and hemoglobin as a rule is different. The values of the apparent E _act proteinases of intestinal mucosa for casein in most cases are higher than those of enteral microbiota, while those for hemoglobin, on the contrary, are lower. The lowest values of relative proteinase activities for casein in the zone of low temperatures (38 and 45.3% of the maximal activity) and the E_act value (less than 2.0 kcal/mol) are found at study of proteinases of enteral microbiota in common perch and crucian carp. The latter indicates a significant adaptability of the enteral microbiota proteinases of common perch and crucian carp to functioning at low temperatures.     

Impact of polychlorinated biphenyls on the activity of intestinal proteinases and carbohydrases in juvenile roach Rutilus rutilus (L.)

The chronic effects that polychlorinated biphenyls (PCBs) have on the activities of proteinases and carbohydrates in intestinal mucosa and chyme in juvenile roach Rutilus rutilus (L.) have been studied for the first time. Upon consuming food with PCB 50.8 ng/g wet weight for 218 days, the exposition of fingerlings in aquariums with dirt bottoms (contents PCB 425.6 ng/g dry weight) reduces the proteolytic activity of mucosa to a greater degree than amylolytic activity; the activity of sucrase changes in different directions. In 2-year-old fish receiving PCB only with food (50.8 ng/g wet weight bottom), proteolytic and amylolytic activities of the mucosa are reduced 18 and 35% in comparison with the control (52 days); the sucrose activity is reduced 13% (52 days) and 22% (169 days). In most cases the relation of amylolytic activity to proteolytic activity in fish of the experimental groups is less than in the control. The enzyme activities in chyme change in different directions, depending on the terms and conditions of the experiment.     

The dynamics of proteinases activity in fish chyme and intestine mucosa upon exposure to fresh and brackish water in vitro

The dynamics of activities of proteinases in roach and perch chyme and in bream intestine mucosa upon exposure to water with various salinities for 96-216 h were studied. Irrespective of the water salinity and source of the enzymes, the proteolytic activities in chyme and intestine mucosa may rise considerably during exposure. This rise is presumably provided by the intestine microflora. This noted phenomenon is least typical for the ichthyophage-facultative benthophage perch when compared to typical benthophages. This is most likely determined by the lower species diversity of the enteral microbiota in perch.     

The influence of testosterone on activity of glycosidases and proteinases in the intestine of the sterlet (Acipenser ruthenus)

Observation of the influence of testosterone (0.7 mg/kg) on the activity of glycosidases and proteinases, which function in the chyme and the mucosa of the sterlet intestine (Acipenser ruthenus), revealed a decrease in enzyme activity of both chains as against that one typical for intact individuals. The activity of the investigated enzymes changes in both the experimental and control groups of fish. Nevertheless, they have unlike dynamics of this activity. In a number of cases, we indicated a significant increase in enzyme activity of both chains in comparison to the control group. We also observed an increase in activity of chyme glycosidases, which was significant on the 21st day as compared to intact fish.     

Effect of pH on the proteinase activities in the intestine mucosa,chyme, and enteral microbiota in the piscivorous fish differing in their ecological traits

The effect of pH on the activity of proteinases of intestine mucosa, chyme, and enteral microbiota was studied in three piscivorous fish species of the Rybinsk Reservoir differing in their ecological traits: pike Esox lucius, burbot Lota lota, and zander Sander lucioperca. In all fish species, studied pH of ten is optimal for the functioning of proteinases of intestine mucosa; in chyme proteinases, optimal pH values vary from six to ten. Optimal pH for functioning of proteinases of enteral microbiota is seven for zander and pike; pH of nine, for burbot. High activity of chyme and microbiota proteinases within the diapason of pH values of six to nine is a characteristic of burbot. Relative activity of proteinases of intestine mucosa in all fish species is not more than 15% of the maximal activity; that of chyme and enteral microbiota is lower than 40% in zander, close to 50% in burbot, and 80 and 50%, respectively, in pike. It is suggested that diversity of the patterns of pH-dependence of enteral microbiota proteinases relates to the specificity of microbiota in various ecological zones of the reservoir (littoral, sublittoral, and bathyal).     

The biochemical composition of chyme in fish species with different diets

The chyme contents of the main biochemical components in fish with different diets vary. Proteins are dominant in the chyme of piscivorous fish (burbot and pike). In the chyme of benthivores (roach and bream), ash is the dominating component. Typical for all fish is the descending lipid gradients with maxima in the proximal section and the ascending ash gradients with maxima in the distal section. The maximum amount of protein was found in the medial part of the intestine. As a rule, there are higher contents of lipids in the chyme of the proximal section and proteins in the chyme of the medial section than in the whole body of fish prey.     

Effect of pH on the activity of proteinases in intestinal mucosa,chyme, and microbiota of fish from the Cuciurgan reservoir

Proteolytic activities of the intestinal mucosa, chyme, and enteral microbiota have been studied in a wide range of pH values in five fish species from the Cuciurgan reservoir (Moldova). Differences in pH dependence of the intestinal proteinase activity of fish are determined by their feeding type. The maximum activity of proteinases is found in the pumpkinseed Lepomis gibbosus. The minimum activity of proteinases has been demonstrated by the zander Zander lucioperca. The pH optimum of the mucosa and chyme in all fish species (except for the European perch Perca fluviatilis) is 10. The pH optimum of the intestinal microflora varies from 6.0 (in the common carp Cyprinus carpio) to 10 (in the crucian carp Carassius carassius), whereas that in the perch from the Cuciurgan and Rybinsk reservoirs is 7. The majority of fish species, mostly Zander lucioperca and Lepomis gibbosus, are characterized by high proteniase activity of the microbiota, in the pH ranging from 6 to 9. It is assumed that proteinases in the enteral microbiota of fish are able to make up for the relatively low activity of those synthesized by their digestive system in the range of low pH values.     

Development of fish communities in lakes after biomanipulation

Biomanipulation measures in the Netherlands are usually a combination of a drastic fish stock reduction and an introduction of pike fingerlings. In three small shallow lakes (Noorddiep, Bleiswijkse Zoom and Zwemlust) these measures resulted in a clear water state and the development of macrophytes. After the measures the fish community developed differently because of the new physical and biological conditions. Results of lake Noorddiep and lake Bleiswijkse Zoom showed that the fish community became more divers. Bream and carp became less dominant and were partly replaced by roach and perch. The importance of the main predator pike-perch was strongly reduced and replaced by pike and perch. The share of piscivorous fish in the total fish stock increased at all sites. The recruitment of young-of-the-year was similar or even higher in the clear overgrown areas than in the turbid water before the measures, but the recruitment of young-of-the-year to older fish differed between the species. Predation by pike and perch could not control the young-of-the-year cyprinids, but their predation may have contributed to the shift from bream to roach, because of selective predation on bream in the open water, while roach was hiding in the vegetation. The macrophytes provide new refugia and feeding conditions that favour roach and perch, but offer relatively poor survival conditions for bream and carp.     

Effect of dexamethasone on activity of glycosidases and proreinases of intestine of sterlet <Emphasis Type="Italic">Acipenser ruthenus</Emphasis>

Effect of dexamethasone (2.0 mg/kg) on activity of enzymes hydrolyzing proteinaceous and carbohydrate food components in the intestine of the starlet Acipenser ruthenus is studied. Dexamethasone modifies the activity of proteinases more than of glycosidases. As a rule, the hormone significantly decreases the level of proteolytic and general amylolytic activity of the intestinal mucosa and chyme in comparison with intact fish on the first day into the experiment and increases it on the 7th or 14th day. The dynamics of activity was different in enzymes of different chains (glycosidase and proteinase) and preparations (the mucosa and chyme).     

Effect of thyroid hormones on activity dynamics of enzymes of intestinal mucosa of juvenile roach <Emphasis Type="Italic">Rutilus rutilus</Emphasis>

The effect of thyroid hormones on activity dynamics of enzymes (proteinases and glycosidases) of intestinal mucosa of juvenile roach Rutilius rutilus was investigated. Application of substances increasing and decreasing the level of thyroid hormones in blood plasma significantly influences the growth rate and the activity of proteinases and glycosidases functioning in the intestinal mucosa. In most cases, the activity level of trypsin-like proteinases and the activity of glycosidases in the fish exposed to triiodothyronine were significantly higher than in the control. The activity level of chymotrypsin-like proteinases in fish form the group with exposure of exogenous triiodothyronine only in the end of the experiment surpassed the values of this parameter in the control fish. In the fish developing at deficiency of thyroid hormones, the growth rate and proteinases activity were significantly lower in comparison with the control.     

Influence of roundup herbicide on the activities of peptidases in the intestines of various fish species

It has been revealed that, as a rule, Roundup herbicide inhibits activities of peptidases in the intestine mucosa and chyme in various fish species, both benthivorous (common carp Cyprinus carpio, silver bream Blicca bjoerkna, roach Rutilus rutilus, and crucian carp Carassius carassius) and piscivorous (perch Perca fluviatilis, pike Esox lucius, and sander Sander lucioperca). The tolerance of peptidases to the herbicide is species-specific. The magnitude and vector of the effects of Roundup depend on its concentration and localization of an enzyme. In the mucosa, the enzymes of common carp and pike are most tolerant, while the enzymes of common carp, silver bream, and pike are most tolerant in the chyme.     

Stress and survival of small pike-perch Sander lucioperca (L.) after trawling and chilling

The mortality and stress responses (plasma cortisol concentration) of undersized (total length, L _T, <370 mm) pike-perch Sander lucioperca caught as by-catch in a trawl fishery were assessed. The effects of three different holding methods on pike-perch caught by trawl were compared: (1) fish that were transferred to ambient-temperature water (15·0–21·4° C) immediately after capture and not exposed to chilling water, (2) fish held in chilling water for 10 min and (3) fish exposed to chilling water for 2 h. The sample fish were held and monitored in individual plastic restrainers at ambient-water temperature for 48 h after each of the handling procedures. Total mortality was similar for fish held in chilling tanks for 10 min (27·2% total mortality) compared to fish that were only held in ambient-temperature water (28·2% mortality). Total mortality reached 91·3% when fish were held in chilled water for 2 h. Mortality and plasma cortisol concentrations correlated inversely with size (96–368 mm L _T) and directly with lake-water temperature (15·0–21·4° C) after treatment. In addition, the effect of chilling was observed in elevated cortisol concentration and delayed start of recovery. The results show that quickly removing (<10 min) undersized pike-perch from chilled water could markedly improve the survival of released fish. Due to delayed recovery, however, fish should be allowed to recover (30–40 min) in a deck tank before release.     

Milk protein digestion and lysosomal proteinases of the ileal mucosa in young rats]

The proteolytic activity of lysosomal and pancreatic proteinases was studied in the chyme and tissue homogenates of the jejunum and ileum of 12- and 30-day rats in order to elucidate whether lysosomal proteinases of the mucous membrane of the ileum participate in cavitary digestion. During milk feeding the proteolytic activity of acid (lysosomal) proteinases in the ileum was 3 times greater than in the jejunum, which has been demonstrated both for the mucous membrane and the contents of these parts of the small intestine. In rats on definitive nutrition the activity of acid proteinases from the jejunum and ileum remained almost unchanged both in the mucous membrane and in the contents. The data obtained also indicate that pancreatic proteinase absorbed from the chyme of the small intestine may participate in parietal digestion.     

Correlation of myofibrillar ATPase activity and myosin heavy chain content in ventricular and atrial myocardium of fish heart

In the fish heart, ventricular and atrial muscles contain different isoforms of native myosin and myosin heavy chain (MyHC) but the significance of this diversity is still not known. We have analysed ventricular and atrial myocardium of six freshwater fish species (goldfish, roach, bream, rudd, perch and pike-perch) using histochemical staining for myofibrillar ATPase activity as well as non-denaturing and SDS gel electrophoreses for native myosin and MyHC content. In the range of fish species studied, the intensity of ATPase reaction was higher in the atrial myocardium than in the ventricular myocardium and the composition of native myosin isoforms differed between these two muscles. The MyHC content in the cardiac muscle showed some species-related differences. In the goldfish, both atrial and ventricular cardiac muscle contained electrophoretically similar MyHC. In the other fish species, however, the ventricular myocardium showed electrophoretically faster MyHC than that present in the atrial myocardium. These results indicate that there are consistent and characteristic species-related differences between the ventricular and atrial muscles at the level of ATPase staining and the type of MyHC expressed. The findings suggest that fish ventricular and atrial muscles may differ in their contractile properties.     

Effects of piscivore-mediated habitat use on growth, diet and zooplankton consumption of roach: an individual-based modelling approach

SUMMARY 1. We used an individual based modelling approach for roach to (i) simulate observed diel habitat shifts between the pelagic and littoral zone of a mesotrophic lake; (ii) analyse the relevance of these habitat shifts for the diet, activity costs and growth of roach; and (iii) quantify the effects of a hypothetical piscivore-mediated (presence of pikeperch) confinement of roach to the littoral zone on roach diet, activity costs and growth.
2. The model suggests that in the presence of pikeperch, roach shifts from zooplankton as the primary diet to increased consumption of less nutritious food items such as macrophytes, filamentous algae and detritus.
3. The growth of roach between May and October was predicted to be significantly higher in the absence of pikeperch, although the net activity costs were about 60% higher compared with the scenario where pikeperch were present.
4. These modelling results provide quantitative information for interpreting diel horizontal migrations of roach as a result from a trade-off between food availability and predation risk in different habitats of a lake.
5. Altering the habitat selection mode of planktivorous roach by piscivore stocking has the potential to reduce zooplankton consumption by fish substantially, and could therefore be used as a biomanipulation technique complementing the reduction of zooplanktivorous fish.     

Habitat shift in roach (Rutilus rutilus) induced by pikeperch (Stizostedion lucioperca) introduction: predation risk versus pelagic behaviour

Changes in the fish community structure and habitat use were followed after the introduction of pikeperch (Stizostedion lucioperca) to the roach-dominated Lake Gjersjøen. Quantitative echosounding showed that the density of juvenile roach (Rutilus rutilus) was dramatically reduced in pelagic areas, from 12 000–15 000 fish/ha to 250 fish/ha, while total fish density remained unchanged in littoral areas. At the same time, the habitat segregation between different size groups of roach was altered as larger roach utilized the pelagic zone after pikeperch introduction. The loss of the pelagic refuge for juvenile roach increased the availability of juvenile roach to littoral predators, notably perch. In littoral areas, the fish community changed from one dominated by roach (> 95%) to one dominated by perch (> 50%).     

The effect of temperature,pH, and heavy metals (copper,zinc) upon proteinase activities in the potential preys for typical and facultative piscivores

Separate and combined action of temperature, pH, and heavy metals (copper and zinc) upon whole body activities of casein-and hemoglobinlytic proteinases were studied in perch (Perca fluviatilis), ruff (Gymnocephalus cernuus), roach (Rutilus rutilus), kilka (Clupeonella cultriventris), and common carp (Cyprinus carpio). Also, these activities were determined in cyprinids’ underyearlings (in sum) dominating the food of typical and facultative piscivores. It was revealed that, following a decrease in temperature to 0°C and in the presence of heavy metals (copper and zinc) at concentrations of 10 mg/l, casein-and hemoglobinlytic proteinase activities decreased statistically significantly in all studied fish. Both decrease and increase in pH values lead to less pronounced changes in the enzymatic activities varied in different species. As a rule, decrease in pH values resulted in considerable increase of the hemoglobinlytic activity, while pH increase caused inconsiderable enzyme activation. Combined action of natural factors and, in some cases, combined action of low temperature and metals, changed the caseinlytic activity to a greater extent than at their separate actions. Magnitude of multifactor effects in most cases is lower than of bifactor effects of temperature and metals.