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.     

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.     

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.     

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.     

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.     

Genome organization of glutamine synthetase genes in rainbow trout (Oncorhynchus mykiss)

Unlike mammals, bony fish appear to possess multiple genes encoding glutamine synthetase (GS), the nitrogen metabolism enzyme responsible for the conversion of glutamate and ammonia into glutamine at the expense of ATP. This study reports on the development of genetic markers for each of the four isoforms identified thus far in rainbow trout (Oncorhynchus mykiss) and their genome localization by linkage mapping. We found that genes coding for GS01, GS02, GS03, and GS04 map to four different linkage groups in the trout genome, namely RT-24, RT-23, RT-08, and RT-13, respectively. Linkage groups RT-23 and RT-13 appear to represent distinct chromosomes sharing duplicated marker regions, which lends further support to the previous suggestion that GS02 and GS04 may be duplicate gene copies that evolved from a whole-genome duplication in the trout ancestor. In contrast, there is at present no further evidence that RT-24 and RT-08 share ancestrally homologous segments and additional genomic studies will be needed to clarify the evolutionary origin of genes coding for GS01 and GS03.     

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.     

Coronary vascular volume remodelling in rainbow trout Oncorhynchus mykiss

The 34% increase in relative ventricular mass (M_rv) resulting from chronic anaemia (induced by an intraperitoneal injection of phenylhydrazine hydrochloride) was accompanied by a 117% increase in coronary vascular volume of diploid rainbow trout Oncorhynchus mykiss. Coronary vascular volume of normocythemic triploid fish was similar to that of normocythemic diploid fish despite a larger M_rv. These observations, in combination with previous studies, suggest that the vascularity of compact myocardium in O. mykiss can vary independently of M_rv.     

Formation of chromosome aberrations in androgenetic rainbow trout Oncorhynchus mykiss

Residues of maternal nuclear DNA in the form of chromosome fragments were observed in the healthy and morphologically normal androgenetic rainbow trout Oncorhynchus mykiss. A hypothetical model for formation of chromosome re‐arrangements caused by the incomplete maternal nuclear DNA inactivation in the androgenetic rainbow trout was proposed in the present paper.     

Routes of entry of Piscirickettsia salmonis in rainbow trout Oncorhynchus mykiss.

Since 1989, Piscirickettsia salmonis, the causal agent of piscirickettsiosis, has killed millions of farmed salmonids each year in southern Chile. The portal of entry for the pathogen was investigated by use of selected experimental infections in juvenile rainbow trout (12 g). The methods used were intraperitoneal injection, subcutaneous injection, patch contact on skin, patch contact on gills, intestinal intubation and gastric intubation. Cumulative mortalities at Day 33 post-inoculation were 98, 100, 52, 24, 24, and 2%, respectively. It was shown that intact skin and gills could be penetrated by P. salmonis. The high mortality obtained in subcutaneously injected fish indicated that skin injuries could facilitate the invasion of this pathogen. Results suggested that the main entry sites are through the skin and gills and that the oral route may not be the normal method by which P. salmonis initiates infection of salmonids.     

Distribution of canthaxanthin in immature rainbow trout Oncorhynchus mykiss serum

• 1.1. The present study was undertaken in order to define the distribution of canthaxanthin between the lipoprotein fractions in serum of immature rainbow trout fed a diet supplemented with synthetic canthaxanthin (80 mg/kg).
• 2.2. Lipoproteins were separated by density-gradient ultracentrifugation.
• 3.3. Canthaxanthin was found in all lipoprotein fractions, in different amounts according to the density of the lipoprotein fraction: VLDL, 13.9%; LDL, 15.2% or LDL, 29.1% since the density of the first fraction was 1.006 g/ml; HDL, 60.4% and VHDL, 10.5%.

     

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.     

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.     

Behavioural variation between piscivore and insectivore rainbow trout Oncorhynchus mykiss

A proactive-reactive continuum integrating multiple (i.e., 3+) dimensions of animal behaviour has been reported as a major axis of behavioural differentiation, but its stability along a biological hierarchy from individuals to populations remains speculative. Piscivore and insectivore rainbow trout (Oncorhynchus mykiss) represent closely related ecotypes with strong ecological divergence driven by selection for a large-bodied piscivorous lifestyle with fast juvenile growth vs. selection for smaller adult body size and lower growth associated with an insectivorous diet. To evaluate whether differences in behaviour between ecotypes are consistent with a proactive-reactive axis and consistent along a biological hierarchy, the authors examined variation in emergence time from a shelter, exploration, activity and predator inspection among individuals, populations and ecotypes of juvenile piscivore and insectivore rainbow trout O. mykiss. As expected, the faster-growing piscivore ecotype was more proactive (i.e., shorter emergence time, exploration and predator inspection) than the more reactive insectivore ecotype. This behavioural contrast was partly maintained across populations, although activity differences were most pronounced among populations, rather than emergence time. Insectivore fry showed substantial variation in behavioural expression among individuals within populations; by contrast, piscivores showed highly similar proactive behaviours with significantly lower inter-individual variation in behavioural expression, suggesting intense selection on behaviour supporting their faster growth. This work suggests that piscivore and insectivore O. mykiss broadly differ in behaviour along a proactive vs. reactive continuum, and highlights the greater multidimensionality of behavioural expression within the insectivore ecotype. Contrasting behaviours between ecotypes may result from differential selection for slow vs. fast juvenile growth and associated metabolism, and may contribute to adult trophic specialization.     

Expression of immune-related genes in rainbow trout (Oncorhynchus mykiss) induced by probiotic bacteria during Lactococcus garvieae infection

The aim of the present study was to investigate the effect of lactic acid bacteria (LAB) on the control of lactococcosis as well as to assess the impact of probiotics on the expression of immune-related genes in the head kidney and intestine of rainbow trout (Oncorhynchus mykiss). Lactobacillus plantarum, Lactococcus lactis and Leuconostoc mesenteroides, were administered orally at 10? CFU g?1 feed to fish for 36 days. Twenty-one days after the start of the feeding period, fish were challenged with Lactococcus garvieae. Only the fish fed the diet containing Lb. plantarum showed significantly (P < 0.05) improved protection against L. garvieae compared to the control. Subsequently, real-time PCR was employed to determine the mRNA levels of IL-1β, IL-8, IL-10 and TNF-α in the head kidney, and IL-8, Tlr5 and IgT in the intestine of the control and Lb. plantarum groups. IL-1β, IL-10 and TNF-α gene expression were significantly up-regulated by Lb. plantarum. Moreover, the mRNA levels of IL-10, IL-8 and IgT were significantly higher in the Lb. plantarum group after L. garvieae infection, suggesting that Lb. plantarum can stimulate the immune response of rainbow trout. PCR-DGGE revealed no detectable levels of the probiotics or the pathogen present on the distal intestinal mucosa. These findings demonstrate that direct probiotic-host interactions with the intestine are not always necessary to induce host stimulatory responses which ultimately enhance disease resistance. Furthermore, as L. garvieae did not colonise the intestinal tract, and therefore likely did not infect via this route, the antagonistic properties of the probiotic candidate towards L. garvieae were likely of little influence in mediating the improved disease resistance which could be attributed to the elevated immunological response.     

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.     

Exhaustive exercise and the cellular stress response in rainbow trout, Oncorhynchus mykiss

The goal of this study was to examine the cellular response to exhaustive exercise in male and female rainbow trout to determine if HSPs are involved in the early stages of the recovery process. Levels of HSPs and key metabolic parameters were measured in white muscle, heart plasma, and blood plasma throughout 6 h of recovery from exhaustive burst exercise. Plasma creatine kinase (CK) was also quantified as an indicator of exercise-induced tissue damage. The observed trends in ATP and lactate were consistent with established patterns of exhaustion and the beginnings of metabolic recovery. However, no upregulation of hsp70, hsp30, or hsp90 was evident in heart or muscle tissue of males or females, and plasma CK measurements suggest that tissue damage was minimal. Our results indicate that hsp70, hsp30, and hsp90 are not part of the early recovery process from burst exercise in fish, perhaps due to the maintenance of core temperatures as well as a lack of exercise-induced tissue damage.     

Cardiorespiratory responses to haemolytic anaemia in rainbow trout Oncorhynchus mykiss

To quantify cardiorespiratory response to experimental anaemia in rainbow trout Oncorhynchus mykiss, a 24 h phenylhydrazine treatment was used to reduce haematocrit to almost one third of its initial value over 4–5 days. In response, relative blood velocity in the ventral aorta (an index of cardiac output) progressively increased to more than double to its normocythaemic value and there was no significant change in routine oxygen uptake. Thus, the primary compensatory response to anaemia was an increase in cardiac output.     

Growth hormone stimulates hepatic lipid mobilization in rainbow trout,Oncorhynchus mykiss

Rainbow trout were used to characterize the direct influence of growth hormone on hepatic lipid mobilization in vitro. Liver was removed from fish fasted 72 h, sliced into 1-mm³ pieces and incubated in Hanks' medium containing ovine or salmon growth hormone (0.28 ng·ml^-1–28 g·ml^-1). Lipid mobilization, resulting from triacylglycerol hydrolysis, was evaluated by fatty acid and glycerol release into culture medium. Control rates of fatty acid release and glycerol release were 0.95±0.16 (mean ± SE) and 0.88±0.28 mol·l^-1·mg fresh weight, respectively. Both ovine growth hormone (28 ng·ml^-1) and salmon growth hormone (28 ng·ml^-1) stimulated fatty acid release into culture medium, increasing rates by 112% and 97%, respectively, during the course of a 24-h incubation. Glycerol release was similarly augmented by growth hormone treatment. Growth hormone-stimulated metabolite release became evident within 12 h and persisted for up to 72 h. The presence of amino acids in the culture medium potentiated the lipolytic action of growth hormone. Ovine growth hormone (28 ng·ml^-1) in the presence of amino acids stimulated a 53% increase in fatty acid, and a 108% increase in glycerol, release over rates observed in the absence of amino acids. Salmon growth hormone (28 ng·ml^-1) in the presence of amino acids stimulated a 53% increase in fatty acid, and a 44% increase in glycerol, release over rates observed in the absence of amino acids. Ovine growth hormone (28 ng·ml^-1) also stimulated gluconeogenesis, as indicated by a 75% increase in phosphoenolpyruvate carboxykinase activity in liver pieces incubated in the presence of amino acids. These results indicate that growth hormone directly stimulates lipid breakdown in the liver of trout and that amino acids potentiate growth hormone-stimulated lipolysis.Abbreviations AA amino acid(s) - dGDP deoxy-guanosine diphosphate - ED ₅₀ 50% effective dose - FA fatty acid(s) - fw fesh weight - GH growth hormone - Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid - MS-222 tricaine methanesulfonate - MEM minimum essential medium - oGH ovine growth hormone - PEPCK phosphoenolpyruvate carboxykinase - PK_c protein kinase C - rpm revolutions per minute - sGH salmon growth hormone - TG triacylglycerol - w/v weight per volume This paper was presented in abstract form at the Annual Meeting of the American Society of Zoologists, Dec. 26–30, 1991, Atlanta, GA