Proteolytic activity in some freshwater animals and associated microflora in a wide pH range.

Proteolytic activity in some freshwater animals (crustacean plankton, sandhopper Amphipoda sp., larvae of chironomids Chironomus sp., oligochaetes Oligohaeta sp., dreissena Dreissena polymorpha, roach Rutilus rutilus heckelii, rudd Scardinius erythrophthalmus, ruff Acerina cernua, and monkey goby Neogobius fluviatilis) prevailing within the food of fishes of various ecological groups as well as in their associated microflora in a wide pH range was investigated. It has been shown that the optimum pH of proteases in the animals' whole organism varies: 6.0 for sandhopper; 8.0 for chironomid larvae, oligochaetes, monkey goby, and ruff; 8.0-9.0 for zooplankton; and 10.0 for roach and rudd. The optimum pH of associated microflora proteases is 6.0 for monkey goby; 7.0 for sandhopper and roach and ruff ; 8.0-9.0 for oligochaetes; 9.0 for zooplankton; and 10.0 for chironomid larvae and rudd. The compensatory role of food items and enteric microbiota proteases in digestive processes in fish of different ecological groups at low pH is discussed.

Role of peptidases of the intestinal microflora and prey in temperature adaptations of the digestive system in planktivorous and benthivorous fish.

Many fish enzymatic systems possess limited adaptations to low temperature; however, little data are available to judge whether enzymes of fish prey and intestinal microbiota can mitigate this deficiency. In this study, the activity of serine peptidases (casein-lytic, mainly trypsin and hemoglobin-lytic, mainly chymotrypsin) of intestinal mucosa, chyme and intestinal microflora in four species of planktivorous (blue bream) and benthivorous (roach, crucian carp, perch) was investigated across a wide temperature range (0-70 °C) to identify adaptations to low temperature. At 0 °C, the relative activity of peptidases of intestinal mucosa (<13%) and usually intestinal microflora (5-12.6%) is considerably less than that of chyme peptidases (up to 40% of maximal activity). The level of peptidase relative activity in crucian carp intestinal microflora was 45% of maximal activity. The shape of t°-function curves of chyme peptidase also differs in fish from different biotopes. Fish from the littoral group are characterized by a higher degree of adaptation of chyme casein-lytic peptidases to functioning at low temperatures as compared to fish from the pelagic group. The role of intestinal microbiota and prey peptidases in digestive system adaptations of planktivorous and benthivorous fish to low temperatures is discussed.

[THE ROLE OF FOOD OBJECTS AND ENTERAL MICROBIOTA PROTEASES IN NUTRITIVE AND TEMPERATURE ADAPTATIONS OF THE DIGESTIVE SYSTEM IN FISH].

The review presents data on the activity and some temperature characteristics of proteases in the potential food objects of fishes and some enteral microbiota representatives that provide induced autolysis and symbiotic digestion. It is shown that during the active feeding period the total protease activity in the prey tissues exceeds the total protease activity in the fish gastric mucosa by 5-10 times. At low temperature, the relative activity of the prey tissue lysosomal hydrolases (20-35%) and the enteral microbiota enzymes (up to 45%) may exceed that of proteases synthesized by the hepatopancreas and functioning in the consumers' intestinal mucosa (less than 10% maximal activity). The data presented indicate the important role of proteases of food objects and enteral microbiota in nutritive adaptations of the fish digestive system.

[The effect of magnetic fields on the activity of proteinases and glycosidases in the intestine of the crucian carp Carassius carassius].

It has been demonstrated by the example of the crucian carp (Carassius carassius) that a 1-hour stay of fish in a combined magnetic field with resonance parameters for calcium ions decreases the proteolytic and amylolytic activities of their intestinal enzymes. It has been found that a 1-hour exposure to a combined magnetic field with resonance parameters for potassium ions has almost no effect on the activity of proteinases, but it decreases the amylolytic activity. It has been noted that the activity of proteases and glycosidases is lower under hypomagnetic conditions. Upon the inversion of the vertical component of the geomagnetic field, the proteolytic activity of the intestinal mucosa in C. carassius decreases, while the amylolytic activity becomes higher compared to the control. Possible effects of magnetic fields on the activity of digestive hydrolases in fish are discussed.

[The effects of geomagnetic storms on proteinase and glycosidase activities in fish intestinal mucosa].

It has been demonstrated that the glycosidase activity of cyprinoid fishes (carp and crucian carp) exposed to a geomagnetic storm for up to 20 h considerably decreases; however, the proteinase activity is weakly altered (a statistically significant decrease in the enzyme activity has been observed only in fasting fish). An in vitro study of the effects of individual half hour intervals of the geomagnetic storm that correspond to the main and recovery phases on the same enzyme activities demonstrates the opposite trend. Independently of the experimental conditions, geomagnetic storms have been shown to influence the enzyme system of fasting fish negatively.

The long-term effect of serotonin on the thermoregulatory behavior in juvenile cyprinidae (Cyprinus carpio and Carassius auratus).

The effect of serotonin after intracerebroventricular (ICV) injections in dosage of 0.3 and 0.15 µg/g of the body weight on the thermoregulatory behavior in juvenile carp Cyprinus carpio L. and goldfish Carassius auratus (L.) has been studied in two experiments of 10- to 11-day duration. It has been found that ICV injection of serotonin in dosage of 0.3 µg/g caused the initial decrease in preferred temperatures (PT) (2-3 days) followed by their further increase (4-8 days after the administration) in carp. ICV injection of serotonin in dosage of 0.15 µg/g caused more durable initial decrease in PT (2-8 days) followed by the increase of once (9-11 days of observation) in goldfish. The values of the ultimate preferred temperature in fish of the experimental group exceeded that in control specimens by 4.1 °C at the first experiment and by 3.1 °C in the second experiment. The data for the first time demonstrated long-term effect of a single ICV injection of serotonin on the thermoregulatory behavior in two closely related species of teleosts.

[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.

Influence of pH upon the activity of glycosidases and proteinases of intestinal mucosa, chyme and microbiota in fish.

It is shown that amylolytic and proteolytic activity of the intestinal mucosa, the chyme and the intestinal flora in the fishes, zander Zander lucioperca (L.), perch Perca fluviatilis L., bream Abramis brama (L.) and roach Rutilus rutilus (L.), belonging according to their feeding habits to different ecological groups at the same pH values as well as in the pH range from 5.0 to 10.0 considerably varies. The glycosidase pH optimum of the mucosa and intestinal microbiota is 7.0, whereas that of the chyme varies from 6.0 (in roach) to 8.0 (in bream). pH optimum of the mucosa proteinases in all fish species is 10.0, whereas that of the chyme and the bacterial flora can be observed in all the range of pH values.

[Proteinases of hydrobionts--potential objects of fish feeding].

The review analyzes data on activities and characteristics of proteinases of digestive system and of cathepsins of various tissues in potential preys of fish differing by the character of feeding. There are presented data on multiple forms and molecular mass of proteinases, species-related differences, dependence of proteinase activities on the life cycle stages, type of nutrition, and biochemical food composition as well as on temperature and pH optima. Role of cathepsin in evolution of enzymatic systems providing degradation of food protein components in fish is discussed.

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

Observation of the influence oftestosterone (0.7 mg/kg) on the activity ofglycosidases and proteinases, which function in the chime and the mucous coat 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 offish. 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 chime glycosidases, which was significant on the 21st day as compared to intact fish.

The dependence on temperature and pH of the effects of zinc and copper on proteolytic activities of the digestive tract mucosa in piscivorous fish and their potential preys.

The dependence of the effects of zinc and copper on the activities of proteinases of the stomach and intestinal mucosa on temperature and pH in four species of boreal piscivorous fish (pike Esox lucius, zander Zander lucioperca, perch Perca fluviatilis and burbot Lota lota) as well as in some of their potential preys (kilka Clupeonella cultriventris, ruff Gymnocephalus cernuus, perch and roach Rutilus rutilus) was investigated. Species-specific differences of the effects of these heavy metals upon the activities of proteinases depending on temperature and pH were demonstrated. It was revealed that the stomach mucosa proteinases were more tolerant to the effects of the studied factors than the intestinal mucosa proteinases, especially true for pike. The effects of the heavy metals on the whole body proteinases of the fishes' potential preys were mostly dependent on temperature than on pH. At pH 3.0, the negative action of zinc and copper on the fish digestive tract mucosa proteolytic activity to a considerable degree was compensated by the high activity of the hemoglobinlytic proteinases, probably, cathepsine D.

[Taurine. Effect on exotrophia and metabolism in mammals and fish].

Data have been presented on the taurine content in various mammalian and fish tissues as well as on pathways of its formation, turnover, and numerous functions. Based on comparison of the character of the taurine effects on various animal functions as well as of the fact of the presence of taurine in the more ancient by origin potential objects of the mammalian and fish nutrition, it is suggested that the taurine polyfunctionality has appeared at different stages of the biota.

[Activity dynamics of proteinases and glycosidases of fish chymus with exposure in fresh and brackish water].

Activity of proteinases of the content of intestines (chymus) of the benthos-eater Carassius carassius fed different diets during prolonged exposure to water is studied. In the process of exposure of the chymus to water, the activity of proteinases decreases. Activity of glycosidases may increase, maximally during the first three days of exposure. This phenomenon suggests the important role of enzymes of the enteral microflora in processes of destruction of proteinaceous and carbohydrate components of the suspension and especially of organic detritus.

[Process of exotrophy in fish. Effects of the heavy metals Zn and Cu].

The review summarizes for the first time the information on effects of Zn and Cu on various links of the fish exotrophy process. It has been shown that essential metals, like the nonessential ones, can produce negative effects on various aspects of the feeding behavior, on sensor systems providing feeding behavior, and on the digestive enzymes realizing digestion in fish of different ecological groups. A particular attention is paid to their different effects on proteinases functioning in stomach and intestine of various fish species as well as on hydrolase activities in their potential food objects (fish and invertebrate animals). Several mechanisms are considered which allow decreasing the negative action of Zn and Cu on the process of fish exotrophy.

[Effect of temperature on proteinase activities in the intestinal chyme and the mucosa of various ecological fish 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 type of feeding. 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 zone of lower temperatures and a larger zone of temperature optimum) as well as of values of apparent energy of activation of the protein hydrolysis process as compared with that in plankto- and ichthyophages--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.

[Study of hydroxyapatite organic-mineral complex influence upon experimental animals white blood].

Biological activity of newly synthesized organic-mineral complexes of hydroxyapatite with carboxymetilcellulose, carraginan and collagen has been studied by reaction of laboratory male rats white blood. The character of influence of each studied substance on the white blood was counted by the dynamic of general number of leukocyte, single leukocyte forms and morphological modification in them in peripheral blood before and after the intraperitoneal injection of the investigated materials. All of the 3 substances activated mechanisms of nonspecific resistance of organism and they were not allergens, because eozinophyllia didn't develop, and they were not toxic either: morphological modifications typical for pathology were absent in formal elements of white blood.

[Activities of proteinases in invertebrate animals--potential objects of fish nutrition. Effects of temperature, pH, and heavy metals].

Differences in the degree of separate and combined effects of temperature, pH, and heavy metals (zinc, copper) on the trypsin- and chymotrypsin-like proteinase activities have been established in the whole body of some invertebrate animals - potential objects of fish nutrition: pond snail Lymnaeae stagnalis, orb snail Planorbis purpura, zebra mussel Dreissena polymorpha, oligochaetae Tubifex sp. and Lumbriculus sp. in total, chironomid larvae Chironimus sp. and Ch. riparus, as well as crustacean zooplankton. It has been shown that enzymes of the potential victim at a low temperature can compensate low activity of intestinal proteinases of fish bentho- and planktophages.

[Detection of sapoviruses in children with acute gastroenteritis in Moscow in 2002-2003].

Sapoviruses were found, for the first time, to be circulating in children with acute gastroenteritis in the city of Moscow. On the basis of a genetic analysis, they were classified as belonging to genotypes 1 and 2. Two groups of sapoviruses that are essentially different from the strains presented now at the GenBank NCBI were described within the case study.

Amylolytic activity in fish intestinal mucosa: temperature effects.

The activity, temperature characteristics and energy of activation of amylolytic enzymes in the intestinal mucosa were studied in six species of fish living in a boreal zone [burbot (Lota lota L.), northern pike (Exos lucius L.), perch (Perca fluviatilis L.), bream (Abramis brama L.), roach (Rutilis rutilis L.), and carp (Cyprinus carpio L.)] and in three species from tropical and subtropical areas [pilchard (Sardina pilchardus W.), jack mackerel (Trachurus trecae C.) and round sardinella (Sardinella aurita V.)]. The amylolytic activity correlated with the feeding habits: it was essentially lower in predators. The enzyme activity at low temperature, relative to the maximal activity, was correlated with the natural environmental temperature where the species lived. At low temperature the relative activity was higher in boreal fish than in tropical and subtropical fish. We found a breakpoint in the Arrhenius plots in all fish species, except for jack mackerel. The energy of activation in predators decreased below the breakpoint in the low-temperature region. The energy of activation in benthophages of the Aral-Ponto-Caspian area was lower at higher temperatures above the breakpoint. A reduction in activation energy in the range of physiological temperatures might indicate adaptation to the environmental temperature.