虹鳟对时间和地点的学习记忆(英文)

为确定虹鳟(Oncorhynchus mykiss)是否能将日投放两次食物的不同时间和地点联系起来,在30天内,于09:00-10:00将食饵投放在水族箱一侧,于15:00-16:00将食饵投放在水族箱另一侧.在第21天和28天,不放食饵以确定虹鳟对时间-地点的学习记忆.结果表明,虹鳟将不同时间和地点联系起来以获取食物,并且在水族箱两个投放食饵之处均表现出预取食活动,提示该物种具有控制时间-地点学习任务的内在机制.     

A blue variant in the rainbow trout, Oncorhynchus mykiss Walbaum

A blue variant of the rainbow trout, which appeared in a French fish farm, displayed an iridescent body color that was cobalt blue on the back, lighter on the undersides, and silvery on the belly and which held up to adult stage. This color was supposed to result from a Tyndall effect involving a structural arrangement of melanin pigments because it disappeared when it was associated with a depigmenting gene. This blue variant appeared to be governed by an autosomal recessive gene. Blue fry survival and body weight were about 25% less than those of wild-type sibs, but no major problem was observed in further breeding performances, including reproduction. These features do not correspond with those of the blue variants previously described in the rainbow trout.     

The physiological responses of freshwater rainbow trout,Oncorhynchus mykiss,during acutely lethal copper exposure

Acutely lethal (24 h) exposure of adult rainbow trout (Oncorhynchus mykiss) to 4.9 mol copper·l^-1 in fresh water (pH 7.9, [Ca²⁺]0.8 mEq·l^-1) caused a rapid decline of plasma Na⁺ and Cl^- and arterial O₂ tension, and initially a pronounced tachycardia. The internal hypoxia probably resulted from histopathologies observed in the gills of fish exposed to copper, such as cell swelling, thickening and curling of the lamellae, and haematomas. Copper cannot therefore be considered purely as an ionoregulatory toxicant during acutely lethal conditions. Mortality during exposure to copper could not simply be explained by the plasma ionic dilution, nor by the internal hypoxia, since arterial O₂ content remained relatively unchanged. Secondary to the ionoregulatory and respiratory disturbances were a number of deleterious physiological responses which included a massive haemoconcentration (haematocrit values as high as 60%) and a doubling of the mean arterial blood pressure. The time-course of these changes suggest that cardiac failure was the final cause of death. In this respect copper exposure resembles low pH exposure in freshwater trout (Milligan and Wood 1982). Copper and H⁺ appear to be similar in both the primary site of their toxic action (the gills) and the secondary physiological consequences which result from acutely lethal exposures. Furthermore, the acute toxicity syndrome observed may be common to many metals which cause ionoregulatory and/or respiratory problems in freshwater fish.Abbreviations C _aO₂ arterial oxygen content - FR water flow rate - Hb haemoglobin - Hct haematocrit - H _m ⁺ net metabolic acid load - IU international unit - MABP mean arterial blood pressure - MCHC mean corpuscular haemoglobin content - MO₂ rate of oxygen consumption - P _aCO₂ arterial carbon dioxide tension - P _aO₂ arterial oxygen partial pressure - T _amm total ammonia (=NH₃+NH ₄ ⁺ ) - TCO₂ total carbon dioxide - TOC total organic carbon - %Hb–O₂ percentage of haemoglobin saturated with oxygen     

Brain distribution of myosin Va in rainbow trout Oncorhynchus mykiss

This study presents data on myosin Va localization in the central nervous system of rainbow trout. We demonstrate, via immunoblots and immunocytochemistry, the expression of myosin Va in several neuronal populations of forebrain, midbrain, hindbrain and spinal cord. The neuronal populations that express myosin Va in trout constitute a very diverse group that do not seem to have many specific similarities such as neurotransmitters used, cellular size or length of their processes. The intensity of the immunoreactivity and the number of immunoreactive cells differ from region to region. Although there is a broad distribution of myosin Va, it is not present in all neuronal populations. This result is in agreement with a previous report, which indicated that myosin Va is approximately as abundant as conventional myosin II and kinesin, and it is broadly involved in neuronal motility events such as axoplasmatic transport. Furthermore, this distribution pattern is in accordance with what was shown in rats and mice; it indicates phylogenetic maintenance of the myosin Va main functions.     

Marker-assisted estimation of quantitative genetic parameters in rainbow trout,Oncorhynchus mykiss

Estimation of quantitative genetic parameters conventionally requires known pedigree structure. However, several methods have recently been developed to circumvent this requirement by inferring relationship structure from molecular marker data. Here, two such marker-assisted methodologies were used and compared in an aquaculture population of rainbow trout (Oncorhynchus mykiss). Firstly a regression-based model employing estimates of pairwise relatedness was applied, and secondly a Markov Chain Monte Carlo (MCMC) procedure was employed to reconstruct full-sibships and hence an explicit pedigree. While both methods were effective in detecting significant components of genetic variance and covariance for size and spawning time traits, the regression model resulted in estimates that were quantitatively unreliable, having both significant bias and low precision. This result can be largely attributed to poor performance of the pairwise relatedness estimator. In contrast, genetic parameters estimated from the reconstructed pedigree showed close agreement with ideal values obtained from the true pedigree. Although not significantly biased, parameters based on the reconstructed pedigree were underestimated relative to ideal values. This was due to the complex structure of the true pedigree in which high numbers of half-sibling relationships resulted in inaccurate partitioning of full-sibships, and additional unrecognized relatedness between families.     

Peripheral serotonin dynamics in the rainbow trout (Oncorhynchus mykiss)

Serotonin (5-hydroxytryptamine, 5-HT) occurs in a wide range of tissues throughout the body of the rainbow trout. Results reported here indicate that the main peripheral sources of serotonin are the intestinal tract and the gill epithelium (levels above 1500 ng/g). The high intestinal serotonin concentration is mostly due to serotoninergic nerve fibres, which are present at high density in the intestinal wall. Only about 2% of serotonin is associated with mucosal enterochromaffin cells. In the remaining tissues studied serotonin concentration was below 160 ng/g: the highest concentrations were seen in the anterior and posterior kidneys, followed by the liver, heart, and spleen. 5-Hydroxyindolacetic acid (5-HIAA) levels, except in plasma, were generally lower than serotonin levels, and were below our detection limits in heart, spleen and posterior kidney. Acute d-fenfluramine treatment (5 or 15 mg/kg i.p.) significantly increased 5-HIAA/5-HT ratio in the anterior intestine, pyloric caeca and plasma. Serotonin released from intestinal serotoninergic fibres in response to d-fenfluramine treatment is metabolized locally, and only a small part reaches the blood, from where it can be taken up and metabolized by other peripheral tissues, such as the liver and gill epithelium. The non-metabolized serotonin pool in the blood appears to be located extracellularly, not intracellularly as in mammals. In view of these findings, we present an overview of peripheral serotonin dynamics in rainbow trout.     

Flavobacterium psychrophilum, invasion into and shedding by rainbow trout Oncorhynchus mykiss

The infection route of Flavobacterium psychrophilum into rainbow trout Oncorhynchus mykiss was studied using bath and cohabitation challenges as well as oral challenge with live feed as a vector. Additionally, the number of bacterial cells shed by infected fish into the surrounding water was determined in the cohabitation experiment and in challenge experiments at 3 different water temperatures. The experiments showed that skin and skin mucus abrasion dramatically enhanced the invasion of F. psychrophilum into the affected fish in bath and cohabitation challenges. Disruption of the skin is discussed as an important invasion route for F. psychrophilum into the fish. The shedding rate of F. psychrophilum by infected fish was associated with water temperature and the mortality of the infected fish. High numbers of F. psychrophilum cells were released into the water by dead rainbow trout during a long time period compared to the numbers of cells shed by live fish. The results emphasise the importance of removing dead and moribund fish from rearing tanks in order to diminish the infection pressure against uninfected fish in commercial fish farms. In immunohistochemical examinations of organs and tissues of orally infected fish, F. psychrophilum cells were detected in only 1 fish out of 31 studied. Mortality of the orally challenged fish was not observed in the experiment.     

Streptococcus iniae type II infections in rainbow trout Oncorhynchus mykiss

Clinical and pathological findings (anorexia, hemorrhage, lethargy, loss of orientation and exophthalmia) indicated that Streptococcus iniae type II is responsible for a fatal disease in rainbow trout. Histopathological findings revealed that S. iniae type II produces a systemic disease, including a diffuse necrotizing myositis. The distribution of viable bacteria in infected tissues substantiated the pathological findings, confirming that S. iniae type II is responsible for a generalized septic disease of rainbow trout.     

Evidence for an intrarenal renin-angiotensin system in the rainbow trout, Oncorhynchus mykiss

Physiological and molecular approaches were used to investigate the existence of an intrarenal renin-angiotensin system (RAS) in rainbow trout. Inhibition of angiotensin-converting enzyme by captopril (5 x 10(-4 )M) rapidly decreased vascular resistance of the trunk of the trout, perfused at 19 mmHg, resulting in an increased perfusate flow rate and a decreased intrarenal dorsal aortic pressure. A profound diuresis occurred in the in situ perfused kidney and reflected both increased glomerular filtration rates and decreased water reabsorption (osmolyte reabsorption was unchanged). Renal and vascular parameters recovered once captopril treatment was stopped. Diuretic and vascular effects of captopril on the in situ trout kidney concur with an inhibition of known vasoconstrictor and antidiuretic actions of angiotensin II. However, at a higher perfusion pressure (28 mmHg), captopril had no effect on intrarenal aortic pressure or perfusate and urine flow rates, suggesting that the trout intrarenal RAS is activated by low perfusion pressures/flows. Existence of the renal RAS in trout was further supported by evidence for angiotensinogen gene expression in kidney as well as liver.     

Analysis of chorion hardening of eggs of rainbow trout, Oncorhynchus mykiss

We estimated changes of chorion hardness of rainbow trout (Oncorhynchus mykiss) egg by the use of three parameters, namely increase of resistance of an egg to rupture by extraneously applied pressure, decrease of solubility of chorion proteins in 8 mol/L urea and a change in the content of γ-glutamyl-ε-lysine crosslink. Unfertilized egg chorions became hardened after egg activation. During chorion hardening, 49, 56 and 65 kDa protein components of the chorion gradually disappeared, high molecular weight intermediates (113,160–170 and higher than 250 kDa) were newly formed and, finally, all components became undetectable by sodium dodecylsulfate-polyacrylamide gel electrophoresis. The content of γ-glutamyl-ε-lysine (γ-Glu-ε-Lys) crosslink in the chorion increased after hardening. Chorion hardening was inhibited by the incorporation of monodansyl-cadaverine, a competitive inhibitor for transglutaminase (TGase), into the chorions. TGase activity was detected in unfertilized eggs and localized in the chorion fraction rather than in the ooplasmic fraction. The findings suggest that chorion hardening depends upon polymerization of the chorion components by TGase-dependent γ-Glu-ε-Lys crosslink formation.     

Testis transplantation in male rainbow trout (Oncorhynchus mykiss)

The objective of the present study was to establish a procedure for the transplantation of an intact testis from one male rainbow trout (Oncorhynchus mykiss) to another individual and evaluate the reproductive function of the transplanted testis at sexual maturity. Isogenic (cloned) male rainbow trout were produced by crossing a completely homozygous male (YY) with a homozygous female (XX) to eliminate any problem of tissue rejection. Transplantation was performed on four pairs of sexually immature animals (n = 8); each served both as a donor and recipient. The left testis was removed by making a ventral midline incision to expose the body cavity and gonads. The left testis was disconnected at the anterior and posterior points of attachment and transferred to the recipient fish where it was placed in position adjacent to the pyloric cecae. The right testis was left intact. After 4 wk, the fish were injected (i.p.) twice weekly for 8 or 9 wk with salmon pituitary extract (1.5 mg/kg) to induce precocious sexual maturation. A similar number of untreated fish were maintained as controls. Following this treatment, all the fish were killed, and the right (intact) and left (transplanted) testes were removed, weighed, and sampled for sperm. Although the mean weights of the left, transplanted testes were significantly (P: < 0.05) smaller than the intact testes (transplants = 1.2 g; intact = 3.9 g), transplanted testes were present in all animals, had increased in mass, and were sexually mature containing sperm. The mean fertility, as measured by the proportion of eggs completing first cleavage, of sperm derived from transplanted testes (92%) was no different from the sperm obtained from intact testes (84%). Similarly, there was no difference in the number of embryos attaining the eyed stage of development, after 18 days of incubation, that were derived from transplanted (84%) or intact testes (85%).     

Purification and characterization of calpain and calpastatin from rainbow trout, Oncorhynchus mykiss

Although the calpain system has been studied extensively in mammalian animals, much less is known about the properties of μ-calpain, m-calpain, and calpastatin in lower vertebrates such as fish. These three proteins were isolated and partly characterized from rainbow trout, Oncorhynchus mykiss, muscle. Trout m-calpain contains an 80-kDa large subunit, but the  26-kDa small subunit from trout m-calpain is smaller than the 28-kDa small subunit from mammalian calpains. Trout μ-calpain and calpastatin were only partly purified; identity of trout μ-calpain was confirmed by labeling with antibodies to bovine skeletal muscle μ-calpain, and identity of trout calpastatin was confirmed by specific inhibition of bovine skeletal muscle μ- and m-calpain. Trout μ-calpain requires 4.4 ± 2.8 μM and trout m-calpain requires 585 ± 51 μM Ca²⁺ for half-maximal activity, similar to the Ca²⁺ requirements of μ- and m-calpain from mammalian tissues. Sequencing tryptic peptides indicated that the amino acid sequence of trout calpastatin shares little homology with the amino acid sequences of mammalian calpastatins. Screening a rainbow trout cDNA library identified three cDNAs encoding for the large subunit of a putative m-calpain. The amino acid sequence predicted by trout m-calpain cDNA was 65% identical to the human 80-kDa m-calpain sequence. Gene duplication and polyploidy occur in fish, and the amino acid sequence of the trout m-calpain 80-kDa subunit identified in this study was 83% identical to the sequence of a trout m-calpain 80-kDa subunit described earlier. This is the first report of two isoforms of m-calpain in a single species.     

Identification and distribution of CCK-related peptides and mRNAs in the rainbow trout, Oncorhynchus mykiss

Peptides homologous to mammalian cholecystokinin (CCK), and their corresponding cDNAs, have been isolated and sequenced from the rainbow trout, Oncorhynchus mykiss. Three cDNAs encoding CCK-like preprohormones were identified from the brain. The cDNAs encode three different putative CCK-8 peptides containing Asn, Leu or Thr, in position 6 (counting from the C-terminus). Hence, the trout CCKs are named CCK-N, CCK-L and CCK-T respectively. RT-PCR showed differential expression of the three mRNAs although all were detected in the brain and intestine, similar to the expression pattern of CCK in tetrapods. In situ hybridization on trout brain sections using (35)S-labeled gene-specific antisense oligonucleotides showed that the three mRNAs were present in different parts, suggesting that the three CCK peptides may have different functions in the brain. Purification of CCK-immunoreactive material from the trout brain resulted in two CCK octapeptides: DYNGWMDF(.)NH2 (CCK-N) and DYLGWMDF(.)NH2 (CCK-L) present in equal amounts. In the pyloric caeca, three forms of CCK-L were identified, consisting of 7, 8 and 21 residues, respectively. The last was dominating and had the sequence ASGPGPSHKIKDRDYLGWMDF(.)NH2. All isolated peptides were fully sulfated. The trout is the first species in which three different CCK-like cDNAs have been identified.     

Novel cell types isolated from the skin of rainbow trout, Oncorhynchus mykiss

Cells were isolated from the skin of rainbow trout, Oncorhynchus mykiss , by collagenase digestion and were observed using light and electron microscopy. Four novel cell types were identified and are described herein.     

Immunohistochemical localization of rainbow trout ladderlectin and intelectin in healthy and infected rainbow trout (Oncorhynchus mykiss)

In the present study, the pattern of immuno-reactive ladderlectin and intelectin in healthy rainbow trout is compared to rainbow trout infected with a variety of infectious agents. In healthy rainbow trout, both proteins were localized to individual epithelial cells of the gill and intestine and both proteins were clearly demonstrated within cytoplasmic granules of polymorphonuclear leucocytes and macrophages/monocytes found in blood vessels, hepatic sinusoids, renal interstitium, mucosal epithelium and submucosa of normal intestine. In tissue from infected rainbow trout, there was an overall relative increase in both lectins compared to healthy fish and both proteins were detected in extra-cellular spaces surrounding bacteria, fungi and protozoa. Increased distribution and density of both RTLL and RTInt was demonstrated along mucosal surfaces and within inflammatory leucocytes in infected tissues and immune related organs. These findings represent one of the few examples of in vivo association of defence lectins and infectious agents.     

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.     

Histomorphometrical studies of vertebral bone condition in farmed rainbow trout,Oncorhynchus mykiss

A major problem for the fish farming industry is to find reliable indicators of bone condition that could help to prevent vertebral abnormalities. Here, we summarize the main results of two recent studies aiming to assess the variation of two vertebral bone variables (bone mineralization and vertebral total bone area) during rainbow trout grow‐out in several French farms. We provide evidence for a wide range of variation for these parameters and for the occurrence of vertebral bone abnormalities, and new data on vertebral structure in trout reared either in various fish farms (influence of rearing conditions) or at different temperatures (influence of various growth rates). Although further experiments are needed to understand bone metabolism in trout, these findings increase our knowledge on growth and modelling of vertebrae, and provide valuable data that will enable comparisons in the future.     

Age-related changes in mitochondrial membrane composition of rainbow trout (Oncorhynchus mykiss) heart and brain

Membrane composition, particularly of mitochondria, could be a critical factor by determining the propagation of reactions involved in mitochondrial function during periods of high oxidative stress such as rapid growth and aging. Considering that phospholipids not only contribute to the structural and physical properties of biological membranes, but also participate actively in cell signaling and apoptosis, changes affecting either class or fatty acid compositions could affect phospholipid properties and, thus, alter mitochondrial function and cell viability. In the present study, heart and brain mitochondrial membrane phospholipid compositions were analyzed in rainbow trout during the four first years of life, a period characterized by rapid growth and a sustained high metabolic rate. Specifically, farmed fish of three ages (1-, 2- and 4-years) were studied, and phospholipid class compositions of heart and brain mitochondria, and fatty acid compositions of individual phospholipid classes were determined. Rainbow trout heart and brain mitochondria showed different phospholipid compositions (class and fatty acid), likely related to tissue-specific functions. Furthermore, changes in phospholipid class and fatty acid compositions with age were also tissue-dependent. Heart mitochondria had lower proportions of cardiolipin (CL), phosphatidylserine (PS) and phosphatidylinositol, and higher levels of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) with age. Heart mitochondrial membranes became more unsaturated with age, with a significative increase of peroxidation index in CL, PS and sphingomyelin (SM). Therefore, heart mitochondria became more susceptible to oxidative damage with age. In contrast, brain mitochondrial PC and PS content decreased in 4-year-old animals while there was an increase in the proportion of SM. The three main phospholipid classes in brain (PC, PE and PS) showed decreased n-3 polyunsaturated fatty acids, docosahexaenoic acid and peroxidation index, which indicate a different response of brain mitochondrial lipids to rapid growth and maturation.     

Patterns of transgene inheritance in rainbow trout (Oncorhynchus mykiss).

There have been very few studies of the inheritance of introduced genes (transgenes) in fish. We have followed the inheritance of the mammalian fusion gene MTrGH from founder generation transgenics (originating from eggs microinjected with the MTrGH DNA) to offspring in crosses with control fish. Initial screening of the founder generation transgenics was by analysing DNA from blood samples. Only three out of six fish which carried the novel gene in blood DNA transmitted it to their offspring, despite the presence of the gene in DNA extracted from the sperm of all four male fish in this group. The frequency of transgenics in the progeny groups from the three fish which transmitted the gene varied widely: in one of these groups more than one type of MTrGH restriction pattern was found. These results suggest widespread mosaicism in founder generation transgenics.