Ubiquitin genes in rainbow trout (Oncorhynchus mykiss)

Ubiquitin is a small protein involved in intracellular proteolysis. It is highly conserved throughout eukaryotic phyla and has been detected in such diverse species as yeast, barley, Drosophila and man. A previous study showed that chromatin of rainbow trout testis contains free ubiquitin with a sequence similar to that of other phyla. In the present study, which focused on rainbow trout but included eleven other species, it is shown that fish ubiquitin genetic organisation and expression are similar to those of other phylogenetic groups through the following set of observations: (a) Multiple loci were detected, (b) These loci encode repeats of ubiquitin, (c) Although the DNA sequences are not conserved, the encoded amino acid sequences are fully conserved, (d) The expression of ubiquitin was influenced by cell culture conditions and viral infection.     

Low social status impairs hypoxia tolerance in rainbow trout (Oncorhynchus mykiss)

In the present study, chronic behavioural stress resulting from low social status affected the physiological responses of rainbow trout (Oncorhynchus mykiss) to a subsequent acute stressor, exposure to hypoxia. Rainbow trout were confined in fork-length matched pairs for 48-72?h, and social rank was assigned based on behaviour. Dominant and subordinate fish were then exposed individually to graded hypoxia (final water PO(2), PwO(2)?=?40?Torr). Catecholamine mobilization profiles differed between dominant and subordinate fish. Whereas dominant fish exhibited generally low circulating catecholamine levels until a distinct threshold for release was reached (PwO(2)?=?51.5?Torr corresponding to arterial PO(2), PaO(2)?=?24.1?Torr), plasma catecholamine concentrations in subordinate fish were more variable and identification of a distinct threshold for release was problematic. Among fish that mobilized catecholamines (i.e. circulating catecholamines rose above the 95% confidence interval around the baseline value), however, the circulating levels achieved in subordinate fish were significantly higher (459.9?±?142.2?nmol?L(-1), mean?±?SEM, N?=?12) than those in dominant fish (130.9?±?37.9?nmol?L(-1), N?=?12). The differences in catecholamine mobilization occurred despite similar P(50) values in dominant (22.0?±?1.5?Torr, N?=?6) and subordinate (22.1?±?2.2?Torr, N?=?8) fish, and higher PaO(2) values in subordinate fish under severely hypoxic conditions (i.e. PwO(2)?相似文献   

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%).     

Plasma amino acid levels in rainbow trout (Oncorhynchus mykiss)

The time course of plasma amino acid concentrations was studied in adult rainbow trout (300 g mean body weight). After a starvation period of 2 days fish were force-fed either with fish protein concentrate or a mixture of acidic casein and Na-caseinate at a rate of 0.32% CP (N' 6.25) of body weight. Peak levels occurred for feeding fish protein concentrate 6–12 h and for the casein mix 18 h post-feeding. The increase of the essential amino acids was closely correlated to the amino acid profile of the test proteins, whereas the concentration differences of the non-essential amino acids were at no time correlated to the amino acid pattern of fish protein concentrate or even negatively correlated in case of casein. The limiting amino acids in the test proteins were determined by ranking the average concentration increases (decreases) of the individual essential amino acids. Accordingly, arginine and histidine were most deficient in casein; in fish protein concentrate tryptophan seems to be the first limiting amino acid, followed by isoleucine.     

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.     

Monoclonal antibodies to lymphocytes of rainbow trout (Oncorhynchus mykiss)

Monoclonal antibodies (Mabs) to lymphocytes of rainbow trout have been developed by immunisation with synthetic peptides, prepared from selected parts of the alpha- and beta-gene sequences of the T-cell receptor (TCR). Mab 1C2 (TCR beta immunisation) identified lymphocytes in blood (11%), spleen (18%) and in thymus (9%) in flow cytometry analysis (FCM). Immune complexes of lymphocytes coupled to Mab 1C2 was used for further immunisations resulting in numerous supernatants reactive with lymphocytes in FCM, of which Mabs 7A5 and 8H4 were selected for further characterisation. Mab 7A5 identified 31% of lymphocytes in blood and 9% in the spleen. Mab 8H4 labelled 61% and 85% of lymphocytes in the same organs. Mab 8H4 reacted with the majority of the lymphocytes in the thymus (98%). Mabs 1C2, 7A5 and 8H4 recognised surface markers on both Ig(-) and Ig(+) lymphocytes in peripheral blood and in spleen in double staining experiments. An increased proportion of Ig(-) lymphocytes were identified when Ig(+) lymphocytes were eliminated by immunomagnetic separation. No cross-reactivity of Mabs 1C2, 7A5 or 8H4 to anti-thrombocyte Mabs was detected. Mab 1C2 captured molecules of about 40 and also of 55-60kDa, in an immunoprecipitation assay. Mab 7A5 recognised an antigen of approximately 75-80kDa and Mab 8H4 identified proteins of about 70, 100 and 150kDa. Immunohistochemical staining by Mab 8H4 of fixed thymus, revealed a strong labelling of lymphoid cells in the outer zones of thymus. The 8H4 positive lymphoid cells surrounds circular structures, which were not labelled by Mab 8H4. These distinctly appearing structures have a similar shape as nurse cells described in mammals.     

A consolidated linkage map for rainbow trout (Oncorhynchus mykiss)

Androgenetic doubled haploid progeny produced from a cross between the Oregon State University and Arlee clonal rainbow trout (Oncorhynchus mykiss) lines, used for a previous published rainbow trout map, were used to update the map with the addition of more amplified fragment length polymorphic (AFLP) markers, microsatellites, type I and allozyme markers. We have added more than 900 markers, bringing the total number to 1359 genetic markers and the sex phenotype including 799 EcoRI AFLPs, 174 PstI AFLPs, 226 microsatellites, 72 VNTR, 38 SINE markers, 29 known genes, 12 minisatellites, five RAPDs, and four allozymes. Thirty major linkage groups were identified. Synteny of linkage groups in our map with the outcrossed microsatellite map has been established for all except one linkage group in this doubled haploid cross. Putative homeologous relationships among linkage groups, resulting from the autotetraploid nature of the salmonid genome, have been revealed based on the placement of duplicated microsatellites and type I loci.     

Mechanisms behind Pb-induced disruption of Na+ and Cl- balance in rainbow trout (Oncorhynchus mykiss)

The mechanism of Pb-induced disruption of Na(+) and Cl(-) balance was investigated in the freshwater rainbow trout (Oncorhynchus mykiss). Na(+) and Cl(-) influx rates were reduced immediately in the presence of 2.40 +/- 0.24 and 1.25 +/- 0.14 muM Pb, with a small increase in efflux rates occurring after 24-h exposure. Waterborne Pb caused a significant decrease in the maximal rate of Na(+) influx without a change in transporter affinity, suggesting a noncompetitive disruption of Na(+) uptake by Pb. Phenamil and bafilomycin markedly reduced Na(+) influx rate but did not affect Pb accumulation at the gill. Time-course analysis in rainbow trout exposed to 0, 0.48, 2.4, and 4.8 microM Pb revealed time- and concentration-dependent branchial Pb accumulation. Na(+)-K(+)-ATPase activity was significantly reduced, with 4.8 microM exposure resulting in immediate enzyme inhibition and 0.48 and 2.4 microM exposures inhibiting activity by 24 h. Reduced activity was weakly correlated with gill Pb accumulation after 3- and 8-h exposures; this relationship strengthened by 24 h. Reduced Na(+) uptake was correlated with gill Pb burden after exposures of 3, 8, and 24 h. Immediate inhibition of branchial carbonic anhydrase activity occurred after 3-h exposure to 0.82 +/- 0.05 or 4.30 +/- 0.05 microM Pb and continued for up to 24 h. We conclude that Pb-induced disruption of Na(+) and Cl(-) homeostasis is in part a result of rapid inhibition of carbonic anhydrase activity and of binding of Pb with Na(+)-K(+)-ATPase, causing noncompetitive inhibition of Na(+) and Cl(-) influx.     

The dynamics of oocyte growth during vitellogenesis in the rainbow trout (Oncorhynchus mykiss)

This report describes the dynamics of oocyte growth during vitellogenesis in a population of virgin female rainbow trout. Indices of ovarian development increased dramatically during the period of study: the gonadosomatic index (GSI) increased over 50-fold, reaching a peak of 20 just before ovulation; the mean oocyte diameter increased from less than 1 mm to 5.4 mm; and plasma levels of vitellogenin increased from less than 1.5 mg/ml to 25 mg/ml. There were no changes in the numbers of developing oocytes (measuring 0.5 mm or greater in diameter) from the time when the majority of oocytes undergoing secondary development had entered vitellogenesis in August to ovulation in February (averaging 4000 oocytes per fish). The increase in ovary weight during vitellogenesis was, therefore, due to an increase in the size of oocytes rather than to recruitment of more maturing oocytes. The numbers of vitellogenic oocytes in the ovary during the entire study also suggested that atresia of vitellogenic oocytes does not play a prominent role in determining fecundity. During early vitellogenesis, the volume of maturing oocytes within an ovary varied by as much as 250-fold. From September onwards, when all oocytes to be ovulated that season had entered vitellogenesis, a gradual uniformity in size began to develop, such that at ovulation, in February, all the eggs were very similar in size (there was less than a 2-fold variation in volume). The pattern of growth of oocytes in an ovary during vitellogenesis suggests that growth between oocytes is closely coordinated.     

Hydrogen sulfide stimulates catecholamine secretion in rainbow trout (Oncorhynchus mykiss)

We tested the hypothesis that endogenously produced hydrogen sulfide (H(2)S) can potentially contribute to the adrenergic stress response in rainbow trout by initiating catecholamine secretion from chromaffin cells. During acute hypoxia (water Po(2) = 35 mmHg), plasma H(2)S levels were significantly elevated concurrently with a rise in circulating catecholamine concentrations. Tissues enriched with chromaffin cells (posterior cardinal vein and anterior kidney) produced H(2)S in vitro when incubated with l-cysteine. In both tissues, the production of H(2)S was eliminated by adding the cystathionine beta-synthase inhibitor, aminooxyacetate. Cystathionine beta-synthase and cystathionine gamma-lyase were cloned and sequenced and the results of real-time PCR demonstrated that with the exception of white muscle, mRNA for both enzymes was broadly distributed within the tissues that were examined. Electrical field stimulation of an in situ saline-perfused posterior cardinal vein preparation caused the appearance of H(2)S and catecholamines in the outflowing perfusate. Perfusion with the cholinergic receptor agonist carbachol (1 x 10(-6) M) or depolarizing levels of KCl (1 x 10(-2) M) caused secretion of catecholamines without altering H(2)S output, suggesting that neuronal excitation is required for H(2)S release. Addition of H(2)S (at concentrations exceeding 5 x 10(-7) M) to the perfusion fluid resulted in a marked stimulation of catecholamine secretion that was not observed when Ca(2+)-free perfusate was used. These data, together with the finding that H(2)S-induced catecholamine secretion was unaltered by the nicotinic receptor blocker hexamethonium, suggest that H(2)S is able to directly elicit catecholamine secretion via membrane depolarization followed by Ca(2+)-mediated exocytosis.     

Domestication shapes morphology in rainbow trout Oncorhynchus mykiss

In this study, clonal lines from North American resident and migratory populations of rainbow trout Oncorhynchus mykiss adapted to different geographical conditions and with different domestication histories were characterized morphologically. Lines reared in a common‐garden experiment were characterized for external shape and meristic values, searching for a general pattern of morphological variation due to exposure to captive conditions. A sharp distinction was identified between wild and captive lines. The body profile was deeper in captive lines, with longer dorsal and anal fins and shorter and deeper caudal peduncles. Highly significant differences were also identified in meristic values among the lines but no consistent relation between meristic values and domestication status was detected. This morphological characterization will facilitate the selection of lines with divergent phenotypes for subsequent quantitative trait loci analysis, aimed at identifying genome regions linked with morphological adaptive response to captive conditions.     

Antibacterial proteins in rainbow trout, Oncorhynchus mykiss

Antibacterial proteins are an important part of the innate immune system for all animals. They have been extensively studied in mammals, amphibians and invertebrates, but have received only scant attention in fish. Their expression and processing, however, provide a way of monitoring defence vigour during development or with seasonal changes in physiology. The aim of the present work was to identify and characterise antibacterial proteins in rainbow trout. In vitro analyses of extracts of the peripheral blood leucocytes, head kidney leucocytes and mucus from adult unstimulated (non-immune) fish showed marked antibacterial activity against Gram positive bacteria. Fractionation by ion exchange chromatography and RP-HPLC of head kidney extracts showed the presence of two forms of lysozyme but no constitutively expressed antimicrobial proteins of < 10 kDa. By contrast, chromatographic analyses of mucus revealed at least four antibacterial proteins. Two are conventional lysozymes, a third is an unusual lysozyme-like protein with a low isoelectric point, and the fourth is a highly hydrophobic, cationic peptide of c. 3 kDa.     

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.     

Early interactions of Flavobacterium psychrophilum with macrophages of rainbow trout Oncorhynchus mykiss

The early interactions of a low and a highly virulent Flavobacterium psychrophilum strain with head kidney and spleen macrophages of rainbow trout Oncorhynchus mykiss were characterized. The highly virulent strain was killed 5.8 to 11 times less frequently than the low virulent strain. The head kidney macrophages showed a microbicidal activity approximately twice as high as that of the spleen macrophages. A 2- to 3-fold higher production of reactive oxygen species (ROS) was induced by the highly virulent strain than by the low virulent one. The head kidney macrophages produced approximately twice as much ROS as the spleen macrophages. The low virulent strain was killed approximately 10 times more frequently by H2O2 than was the highly virulent strain. In spleen macrophages, the highly virulent strain caused twice as much cytotoxic effects compared to the low virulent strain. In conclusion, virulence in F. psychrophilum appears to be correlated with higher O. mykiss macrophage cytotoxicity and resistance to ROS and, therefore, with enhanced resistance to bacterial killing. Moreover, due to lower ROS production, spleen macrophages have a lower antimicrobial action against F. psychrophilum, compared to head kidney macrophages and, thus, might form a 'safe site' in which bacteria can reside.