Effects of elevated water temperature on the critical swim speeds of yearling rainbow trout Salmo gairdneri

Effects of elevated water temperature on the critical swim speeds of rainbow trout, Salmo gairdneri, were investigated. Trout acclimated to 10°C were exposed to 10, 15, 20 and 20°C while swimming and at rest. Initial swim speed of 20 cms⁻¹ was increased in 10 cms⁻¹ increments every 20 min until the fish fatigued. Critical swim speeds were calculated in absolute values (cms⁻¹) and relative performance values (body lengths s⁻¹). Critical swim speeds were similar at 10, 15 and 25°C. Swimming performance was significantly decreased at 25°C. Performance measured as critical swim speed was unaffected by temperature elevations up to 10°C above acclimation temperature of 10°C.     

Effect of environmental temperature on the phospholipid metabolism of gill mitochondria of Carcinus maenas

The different types of phospholipids extracted from gill mitochondria of crab Carcinus maenas have been analysed and it was found that a significant increase of the phosphatidylethanolamine (PE) content and a concomitant decrease of the phosphatidylcholine (PC) amount are present in animals living in low temperatures. The incorporation of [³H]ethanolamine in total phospholipids, PE and PC, was demonstrated in gill mitochondria and a thermal alteration of the in vivo exchange of PE between mitochondria and 10,000 g supernatant is suggested by the kinetics of the incorporation. It is suggested that the conversion of PE to PC by N-methylation is very low in crab gills. There is a marked action of acclimation temperature on the gills-hemolymph exchange of PC and PE. It is postulated that the changes reported at the level of the PE → PC conversion by N-methylation and in phospholipid exchange between hemolymph and gills could be implicated in adapting the organism to seasonal fluctuations of environmental temperatures.     

Influence of acclimation temperature on GDP-mannose: Dolicholphosphate mannosyltransferase of trout liver (Salmo Gairdneri)

Mannosyltransferase activity has been studied in trout liver microsomes prepared from fish adapted during 1 month at three different temperatures: 7, 15 and 21°C; the purpose of the study was to try and answer this question: is the enzyme sensitive to temperature variations and if so, do optimum pH variations reflect an adaptation to temperature changes? The following effects were observed: 1. Optimum pH values do not vary significantly with incubation temperature; only a discrete shift towards more acidic pH has been observed for trouts raised at 21°C. 2. For trouts raised at 7 and 15°C, the enzymic activity increases slightly with incubation temperature while it remains constant for the trouts acclimated at 21°C. This observation could be explained by a lower level of endogenous dolicholphosphate. 3. At any incubation temperature, the higher the acclimation temperature, the lower the enzymic activity.     

Advancing provision of multi-species fish passage: Behaviour of adult European eel (Anguilla anguilla) and brown trout (Salmo trutta) in response to accelerating flow

The behavioural response of downstream moving European eel (Anguilla anguilla) and brown trout (Salmo trutta) to velocity gradients created by orifice weirs placed in a flume were studied. The aim was to identify interspecific variation and test two hypotheses: (1) a more abrupt velocity gradient would induce a higher avoidance response and over a greater distance, and (2) fish would acclimate to the velocity gradient by incrementally sampling conditions closer to the orifice until successful passage occurred. European eel moved along the channel floor and walls, responding after physical contact with the weir. Brown trout moved downstream head first and switched orientation at the velocity gradient without contacting the structure. Brown trout spent longer than European eel immediately upstream of a channel floor orifice, although time to pass was similar; but less time at a mid-column orifice despite taking longer to pass. The mid-column orifice delayed both species longer. European eel passed orifices head first on initial encounter with no rejections, whereas brown trout passed tail first. Positions where brown trout first switched orientation and closest point to the orifice reached during initial approach occurred closer to a channel floor than mid-column treatment. Brown trout did not appear to acclimate to the velocity gradient by sampling successively closer to the orifice. Interspecific variation in behaviour remains a key challenge in developing multi-species fish passes.     

The effect of temperature on intracellular transport of asialo-glycoproteins in rainbow trout liver

The intracellular pathway of a endocytosed glycoprotein has been studied in rainbow trout ( Oncorhynchus mykiss ) liver by means of differential and isopycnic gradient centrifugation. When ¹²⁵I-tyramine-cellobiose-labelled asialoorosomucoid was injected intravenously, the protein was removed rapidly from the blood by hepatic endocytosis. The tracer was localized initially in a small, slowly sedimenting organelle (endosome) and transferred to the denser lysosomes where degradation took place. This process took several hours at the acclimated temperature of 10 ° C. The transport could be accelerated markedly or retarded by transfer of fish to higher or lower temperatures respectively. The intracellular transport steps were more susceptible to changing temperature than the internalization process. In particular, the degradation was temperature sensitive. These results may have implications for the effects of changing temperature on immune function in fishes. The impairment of transport upon a rapid temperature decrease, will reduce the rate of antigen processing and presentation in these animals.     

An analysis of spatial and environmental factors influencing hybridization between native westslope cutthroat trout (Oncorhynchus clarki lewisi) and introduced rainbow trout (O. mykiss) in the upper Kootenay River drainage, British Columbia

Westslope cutthroat trout (Oncorhynchus clarki lewisi, WCT) and introduced rainbow trout (O. mykiss, RBT) readily hybridize and introgression has occurred in many drainages across the historic native range of WCT. In British Columbia (Canada), the upper Kootenay River drainage is the heart of the westslope cutthroat trout (WCT, Oncorhynchus clarki lewisi) distribution in Canada this drainage harbours native WCT gene pools that are thought to be under threat from hybridization with introduced rainbow trout (RBT, O. mykiss). In this study, we assess the extent and distribution of WCT × RBT hybridization in the upper Kootenay River drainage. We used four diagnostic nuclear loci to determine the extent of hybridization in 981 fish collected from 23 sample localities across 12 different streams in the upper Kootenay River drainage. About 14% (142/981) of individuals were identified as hybrids (an individual with both RBT and WCT alleles), 3.4% (33/981) were identified as pure RBT, and the remaining individuals were identified as pure WCT. Although pure RBT were absent from the majority of locales (20/23), we found evidence of hybridization at 78% (18/23) of the localities and the percentage of heterospecific alleles (% I) ranged from 0.7% to 97.1%. Only 22% (5/23) of the localities showed no evidence of hybridization. Spatial analysis showed clustering among hybridized locations and decreasing hybridization with increasing distance from Koocanusa Reservoir, suggesting that the reservoir acts as a RBT source. We found no evidence that stream order, stream magnitude, or stream elevation influenced the extent of hybridization among localities. We compared our results to an analysis conducted in 1986, which indicated that hybridization is relatively recent in the upper Kootenay River drainage and that it is increasing in magnitude and distribution. In the absence of timely management intervention, the genetic integrity of WCT populations in the heart of their Canadian range may be lost. Our results indicate the dynamic nature of hybridization in fluvial systems and that for closely related taxa such as WCT and RBT, hybridization appears to be largely influenced by physical barriers to dispersal and contact between species.     

Haemodynamic effects of adenosine on gills of the trout (Salmo gairdneri)

Summary The haemodynamic effects of adenosine on gills of the trout (Salmo gairdneri) were studied with in vitro and in vivo preparations.On the isolated head preparation, adenosine induced a decrease of the ventral aortic inflow and of the dorsal aortic outflow. Simultaneously the venous outflow increased. These effects were antagonized by theophylline. Adenosine induced a vasoconstriction in gill arches without filaments perfused by the afferent or the efferent branchial arteries. The efferent vessels were more sensitive to adenosine than afferent vessels. The whole systemic circulation of the isolated trunk did not show any response to adenosine. When adenosine was infused into the ventral aorta of living trout, the gill resistance to blood flow was greatly increased.These results suggest that adenosine is able to control the arterious and venous blood pathways in the trout gills by modulating their vascular resistance.     

Effect of the acclimation to high environmental temperature on the activity of hepatic glycogen phosphorylase (a+b and a), liver glycogen content and blood glucose level in rats

(1) Changes in the activity of hepatic glycogen phosphorylase a+b and a (GPh-ase a+b and a), liver glycogen content and blood glucose level during acclimation to moderate high environmental temperature (35±1 °C) were studied. (2) Experiments were carried out on adult fed Wistar rats of both sexes, previously given either short-term (1, 4 and 7 days) or long-term (14, 21, 30 and 60 days) exposure to high environmental temperature. The controls were continuously kept at room temperature (20±2 °C). (3) The results obtained showed that in the period of short-term exposure the liver glycogen content was decreased significantly (after the first and fourth days in male rats and after first day in female rats) and the GPh-ase a activity increased (after first day in male rats and after first, fourth and seventh day in female rats). Long-term exposure caused significant increased liver glycogen content (beginning from the 14th day in male rats and the 21st day in female rats) until the end of the acclimation period (60 days). The elevated activity of GPh-ase a persists after 14th day of exposure only in female rats while there are no significant changes over the rest of the acclimation period in both sexes. There were no significant changes in total GPh-ase activity during the whole period of exposure. Blood glucose level was significantly decreased throughout the whole period of acclimation to high environmental temperature, in both sexes (except in the 1 day exposed groups). (4) The increased activity of hepatic GPh-ase a and decreased glycogen content suggested that the short-term exposure to heat stimulates the glycogenolytical processes. Decreased blood glucose level, and elevated liver glycogen content (r=-0.7467 in male and r=-0.6548 in female rats) suggested that prolonged exposure to high environmental temperature stimulated glycogenogenesis, without changes in the GPh-ase activity.     

大豆柑桔间作系统中磷的分配和迁移规律研究

用微区试验和³²P同位素示踪技术,比较研究了大豆、柑桔间作和单作条件下,P在大豆和柑桔体中的分配、转移及其在土壤中的迁移规律.结果表明,间作大豆的吸P量和各部位累积P量显著地低于单作大豆;³²P肥料浅施,间作大豆吸收的³²P量显著低于单作大豆;³²P肥料深施,间作大豆吸收的³²P量显著高于单作大豆,但间作不影响P和³²P在各部位的转移和分配.间作柑桔吸收的³²P量显著低于单作柑桔.柑桔新吸收的³²P可快速向地上部分输送,并优先供应生长活跃部位.间作不影响³²P在柑桔各部位的转移和分配,但是P肥深施使柑桔吸收的³²P向地上部分和生长活跃部位的转移速率减慢.间作使土壤中P的生物移动性增强,可促进土壤深层P向土壤浅层迁移.试验结果表明,大豆柑桔间作磷肥的施用深度以保持在20cm以内为佳.     

The ontogeny of drinking in the rainbow trout, Oncorhynchus mykiss (Walbaum)

Drinking was measured by the rate of uptake of tritiated dextran in fresh water by the alevins and fry of rainbow trout at various stages of development during a 40-day post-hatch period. Drinking increased almost S-fold during the initial 16 day yolk-sac stage. Drinking rate increased most between 16 and 23 days, the transitional period between yolk-sac absorption and first feeding. The maximum weight-specific drinkingrateof 3.24μlg⁻¹ h⁻¹ recorded for 40-day-old fry was higher than previously recorded for adults. Abrupt transfer from an adaptation temperature of 10 to 19° C increased drinking significantly (Q₁₀= 1.2), but sudden transfer to 1 1‰ salinity sea water caused a substantial fall in drinking rate in 23-day fry. A 24-h period of adaptation to 1 1‰ and 15‰ salinity restored drinking to a rate similar to that in fresh water. The water drunk by 31-day fry fed to satiation was initially higher than by unfed fry, but drinking rates subsequently fell below the control level. The results are discussed in terms of osmoregulation and the uptake of dissolved or suspended substances by the intestinal tract for the purpose of immunization.     

Effect of temperature on fatty acid composition and development of unfed Siberian sturgeon (A. baerii) larvae

The fatty acid metabolism in fish is influenced by various factors, including fish species, water temperature, water environment and diet supply. The aim of present work is to investigate the fatty acid composition of yolk‐stage Siberian sturgeon larvae reared at three different temperatures. Fertilized Siberian sturgeon eggs were transferred to the Lodi Aquaculture Research Center of the University of Milan, divided in three aquaria, each containing three incubators and incubated at 16°C. After hatching the temperature was switched to 16, 19 and 22°C. Larvae sampling was performed at the end of yolk sac reabsorption. No feed was dispensed during the trial. Eggs and larvae were weighed and fatty acid profile was determined by GC‐FID analysis after lipid extraction by chloroform/methanol mixture and fatty acid transesterification by methanolic hydrogen chloride. The fertilized eggs had a weight of 23.27 mg and a lipid content of 2.67 mg/egg. At hatching, the weight was 12.2 (0.17 SD) mg and lipid content 1.9 (0.6 SD) mg/larva. At the end of the trial, larvae mean weight was 33.6 (3.6 SD), 34.7 (1.8 SD) and 36.9 (1.1 SD) mg, while lipid content was 2.0 (0.3 SD), 2.1 (0.3 SD) and 2.0 (0.2 SD) mg for larvae reared at 16, 19 and 22°C respectively, without statistically significant difference. Larvae subjected to the highest water temperature showed a faster yolk‐sac absorption. No differences were found across temperatures regarding survival rates and regarding ontogenic development. The fatty acid composition of larvae was affected by the temperature. Larvae reared at 16°C had the lowest amount of saturated fatty acids, mainly due to a lower palmitic acid content, that was offset by a higher level of linolenic and linoleic acid, if compared with larvae reared at 19°C and 22°C. The study suggests that at a lower temperature sturgeon spare unsaturated fatty acid consuming preferably saturated fatty acids, increasing our knowledge of the fatty acid metabolism in this species.     

A comparison of the effect of long-term starvation on responses to low-temperature stress by juvenile rainbow (Oncorhynchus mykiss) and brown (Salmo trutta) trout reveal different responses in the two species

Biometric parameters and oxidative stress indicators were measured in liver and muscle samples from rainbow trout and brown trout juveniles exposed to a 45-day starvation period at low water temperature. As a general tendency, hepatic antioxidant enzyme activities in both species increased with fasting to eliminate the harmful effects of reactive oxygen species (ROS). However, the metabolic response to food deprivation in the muscle of each species was different. Lipid peroxidation levels in both species increased with starvation. We concluded that (1) low water temperature enhances ROS production in salmonids because of increased polyunsaturated fatty acid content in the cell membrane; (2) starvation significantly impaired the growth parameters of brown trout, yet the reverse was found for rainbow trout; and (3) despite this negative interaction, brown trout juveniles can physiologically tolerate oxidative stress caused by starvation and can therefore be cultivated under stressful conditions even in their early life stages.     

Effects of glutamine on growth performance,nutrient content,fatty acid profile,and blood parameters of rainbow trout (Oncorhynchus mykiss)

In this study, different amounts of glutamine were added to the diet of rainbow trout, and they were then fed for a period of 90 days. The current research investigated the effects of glutamine on various aspects of rainbow trout, including growth performance, condition factor, viscerosomatic index, hepatosomatic index, carcass composition, fatty acid profile, hematological parameters, and biochemical parameters. The study's findings revealed that adding glutamine to the diet of rainbow trout had a beneficial impact on their growth features. The rainbow trout group that was fed a 2% concentration of glutamine experienced the most notable increase in growth rate. A statistically significant difference in growth was observed among all groups (p < 0.05). Adding glutamine to the diet increased the amount of protein and decreased the fat content in the flesh of the fish. Glutamine exerted an influence on the blood and biochemistry parameters of fish, as well as their fatty acid composition. In conclusion, the inclusion of glutamine in the diet of fish could potentially enhance their immune system, improve the quality of their muscles, and enhance their growth performance.     

环境温度对白头鹎代谢产热和蒸发失水的影响

基础代谢率(BMR)是恒温动物维持正常生理机能的最小产热速率,是动物在清醒时维持身体各项基本功能所需的最小能量值。"能量需求"假设认为,鸟类短期BMR的调整可以通过改变内部器官的大小来适应能量需求。以白头鹎(Pycnonotus sinensis)为研究对象,分别在10℃和30℃的不同环境中适应4周后,测定了其BMR、蒸发失水(EWL)和内部器官(心、肝、肾、胃、小肠和整体消化道)的重量,同时分析了白头鹎内部器官的变化及与BMR的关系。驯化4周后,白头鹎暖温组(30℃)的体重有明显降低的趋势;经协方差校正体重后,低温组(10℃)单位体重BMR与整体BMR明显高于暖温组,同时两组间EWL表现出显著差异。协方差分析表明,低温组白头鹎的肝脏、肾脏、小肠及总消化道重量显著高于暖温组。低温引起白头鹎能量需求增加,内部器官发生相应改变,要求摄入更多的氧气以维持代谢平衡,导致散失更多的蒸发水。