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.     

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.     

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 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.     

Effects of Temperature and pH on Activity of Proteinases of Intestinal Mucosa and Enteral Microbiota of Fish

Separate and combined effects of temperature and pH on activity of proteinases of intestinal mucosa and enteral microbiota were studied in several fish species. There were revealed peculiarities of temperature function of enzymes in microbiota of ichthyophages (a high level of relative activity in the whole range of their vital activity), which indicate the presence of victim-symbiotic adaptations in fish feeding in winter.     

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.     

Diversity of microbial communities of the intestinal mucosa and intestinal contents of fish from Lake Chany (Western Siberia)

The diversity of microbial communities associated with the intestinal mucosa and the intestinal contents of fish with different nutritional profiles have been investigated. Differences in the intestinal microbiota of fish with different dietary preferences have been revealed using group-specific primers for the main large taxa of bacteria. Representatives of the phyla Planctomycetes, Vernicomicrobia, and Cyanobacteria have been detected in the intestinal contents of all investigated nonpredatory (crucian carp, roach, and dace) and predatory (pikeperch, pike, and perch) fish. Representatives of the phylum Firmicutes were detected in the intestinal mucosa and intestinal contents of predatory fish species, but not in those of the nonpredatory 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).     

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.     

Effects of temperature,pH, and heavy metals (copper,zinc) upon proteinase activities in digestive tract mucosa of typical and facultative piscivorous fish

Species-specific differences and effects of natural (temperature, pH) and anthropogenic (zinc, copper) factors upon activities of casein-and hemoglobinlytic proteinases have been studied in the gut mucosa in pike (Esox lucius), zander (Stizostedion lucioperca), burbot (Lota lota) and perch (Perca fluviatilis). It is revealed that the intestine mucosa proteinase activities differ considerably from those ones in the fish stomach mucosa and that studied factors affect these activities to different extents. The stomach mucosa proteinases are most tolerant to the effects of studied factors, which is especially true for pike. The least tolerant are the intestine caseinlytic proteinases (except for the enzymes in perch). The effects of temperature, pH, and heavy metals depend on fish species, factors’ combinations (mono-factor, bi-factor, or multi-factor action) and on factor variability.     

Predation risk and feeding patterns of crucian carp

As part of an experimental study of the direct and indirect effects of piscivory on prey fish, the diets of crucian carp Carassius carassius were compared across sections of a divided pond; two sections were stocked with crucian carp alone and two with crucian carp plus perch Perca fluviatilis . Analysis of crucian gut contents indicated that the composition of invertebrate prey did not differ in the presence v . absence of perch. However, crucians, particularly small individuals (<10cm) that were most vulnerable to predation, displayed a lower intake of invertebrate prey in sections with perch. Although diet composition differed between crucians caught in inshore v. offshore habitats (with habitat use being related to crucian size and the presence or absence of perch), no clear pattern existed between habitat and total food intake. Overall, the major effects of predators on the diet of crucian carp appeared to be caused by increased ecological density (resulting from confinement of small crucians inshore) and reduced activity levels, rather than simple shifts to safer habitats.     

Evidence for somatostatin,gastrin and pancreatic polypeptide-like substances in the mucosa cells of the gut in fishes with and without stomach

Gastrin, pancreatic polypeptide and somatostatin immunoreactive cells in the gut of two fish with stomachs (perch and catfish) and a stomachless fish (carp) were studied by immunocytochemistry. In the gastric mucosa of perch and catfish, cells showing gastrin and somatostatin-like immunoreactivity are found, scattered among the surface mucous cells and mucous neck cells. No pancreatic polypeptide (P.P.) immunoreactive cells are detected in the gastric mucosa. Cells showing gastrin and P.P.-like immunoreactivity are observed in the intestinal mucosa of perch, catfish and carp. In this location no somatostatin immunoreactive cells are found.     

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.     

从ATPase8-6基因研究杂交多倍体鱼线粒体母性遗传

异源四倍体鲫鲤是世界上首例人工培育的两性可育并形成群体的且能自然繁殖的四倍体鱼。本文采用质粒克隆测序法测定了红鲫、异源四倍体鲫鲤、三倍体湘云鲫和三倍体湘云鲤的ATPase8和ATPase6基因全序列 ,结合鲤鱼、日本白鲫和斑马鱼的同源序列 ,对不同倍性水平鲤科鱼类的ATPase8和ATPase6基因进行了比较 ,分析了碱基组成、变异情况以及核苷酸和氨基酸序列差异。红鲫、鲤鱼、异源四倍体鲫鲤、日本白鲫、三倍体湘云鲫和三倍体湘云鲤之间的序列差异为 0 0 % - 1 3 4 % ,它们与外群斑马鱼之间的序列差异为 2 7 9% -31 0 %。用MEGA软件中的MP法、ME法、NJ法和UPGMA法构建分子系统树 ,得到了相似的拓扑结构。结果分析表明 ,人工杂交多倍体异源四倍体鲫鲤、三倍体湘云鲫和三倍体湘云鲤在线粒体ATPase8和ATPase6基因上具有严格的母性遗传特征。值得注意的是 ,异源四倍体鲫鲤经过 1 1代的繁育后 ,与其原始母本红鲫仍然保持了非常高的同源性 ,说明了新的异源四倍体基因库在线粒体ATPase8和ATPase6基因上拥有稳定的遗传特性。对不同倍性鲤科鱼类线粒体ATPase8和ATPase6基因的研究表明 ,ATPase8和ATPase6基因是杂交鱼后代遗传变异研究的一个很好的分子标记     

饲料蛋白水平对方正银鲫幼鱼生长、体成分、肝脏生化指标和肠道消化酶活性的影响

为研究饲料中不同蛋白水平对方正银鲫(Fang zheng Caucian carp)幼鱼生长、体成分、肝脏生化指标和肠道消化酶活性的影响, 配制蛋白水平为30.18%、33.13%、36.16%、39.34%、42.32%和45.46%的6种等脂等能饲料。选取初始质量为(3.10±0.01) g的方正银鲫幼鱼540尾, 随机分成6组, 每组3个重复, 每个重复30尾, 进行为期8周的饲养试验。结果表明: 随着饲料蛋白水平升高, 方正银鲫幼鱼增重率、特定生长率、饲料效率、蛋白质效率、全鱼粗蛋白含量、肝脏谷丙转氨酶和肠道胰蛋白酶活性均先升高后降低, 且在蛋白水平为36.16%时最大, 显著高于其他组(P<0.05); 肝脏总胆固醇和甘油三酯含量均呈逐渐下降趋势, 蛋白水平为30.18%的组显著高于除33.13%组以外的其他各组(P<0.05)。方正银鲫幼鱼特定生长率、蛋白质效率与不同蛋白水平分别进行二次回归分析得, 在试验条件下, 方正银鲫幼鱼饲料中最佳蛋白质水平为35.29%—37.07%。     

Predator recognition and defence strategies in crucian carp, Carassius carassius

Crucian carp from populations that lack piscivores are extremely vulnerable to predation. However, in the presence of piscivores these fish develop an inducible morphological defence, a deep body. This switch from a vulnerable, shallow-bodied morph to a morphologically defended morph makes this species very suitable for investigations of anti-predator strategies, and trade-offs between morphological and behavioural defences. To address these questions, we performed eight different experiments. We found that crucian carp exhibited fright responses to chemical cues from unfamiliar predators (northern pike, perch) when these were fed prey that contained alarm substance (for northern pike: crucian carp, roach; for perch: crucian carp). Cues from small pike that were fed prey that lacked alarm substance (swordtails) caused no significant fright response whereas cues from larger pike with the same diet did. Perch on a chironomid diet elicited weaker but significant fright responses. Starved predators caused as strong fright reactions as recently fed ones did, whereas no response was exhibited towards nonpredatory fish (roach, crucian carp). Crucian carp were able to detect the presence of pike after cues had been diluted to an equivalent of 21 000 l, and larger predators elicited stronger fright responses. Prior experience of predators decreased fright responses. In particular, individuals from populations that coexisted with northern pike responded less to chemical cues from northern pike than individuals without prior experience did. Thus, crucian carp may use both alarm-substance related and predator-related cues to identify predators. Further, they were able to discriminate between large and small predators. Finally, individuals from populations that coexist with predators exhibit less pronounced fright responses. These fish have an induced morphological defence, a deep body, which most likely decreases the need for strong antipredator behaviour.     

Body morphology of crucian carp Carassius carassius in lakes with or without piscivorous fish

Crucian carp Carassius carassius was sampled during 1993 and 1994 in 21 lakes and ponds in east Norway In 10 of these lakes and ponds no piscivorous fish species was present, and in the remaining 11 lakes and ponds predators such as perch Perca fluvtalilis. pike Esox lucius, and trout Salmo trutta were common In general, crucian carp was larger in the lakes with predators than in those without predators The relative body depth (body height/body length) of crucian carp was significantly deeper in populations sympatric with predators (mean 0 358), compared to allopatric populations (mean 0 286) The variation in relative body depth was larger among the sympatric populations than among the allopatric populations The observed difference in relative body depth may be due to 1) predator induced changes m body morphology, 2) increased growth rates in lakes containing predator due to reduced intraspecific competition, and 3) size-selective predation     

Ecological and genetic mechanisms of the dynamics of population abundance in silver crucian carp (Carassius auratus gibelio (Bloch, 1782)) from the Tsimlyansk Reservoir

Silver crucian carp is the dominant commercial fish of the Tsimlyansk Reservoir (the Don River). A retrospective analysis of the ecological and genetic factors determining the dynamics of the silver crucian carp population at different stages of reservoir functioning was performed. At the most recent stage, the lake-swamp environmental conditions suitable for crucian carp and a lack of any dependence on other cyprinid fishes during the reproduction of this species determine its domination in the reservoir??s fish community. The size, sex, and genetic structures of the crucian carp population, characterized by numerous age groups and low linear and weight growth rates, are presented.     

Proteinases of potential objects of fish nutrition

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 nutrition. 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.     

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.