Meristic variation among world hatchery stocks of rainbow trout,Salmo gairdneri Richardson

Synopsis Sixteen meristic characters were examined among 10 stocks of rainbow trout to establish their inter- and intrastock variability and relative discriminating power. The number of vertebrae, dorsal fin rays, scales above and below and lateral line, oblique scale rows and pectoral fin rays were found to be the most useful meristic characters in identifying stocks. Examination of the extent of meristic divergence among 10 hatchery or naturalized stocks from various regions of the world, using analysis of variance, the generalized distance function and per cent overlap, revealed that each stock exhibited highly significant differences in at least one meristic character, thereby demonstrating a high degree of intraspecific variability in meristic expression.In multivariate terms, stocks from Idaho and Alaska were almost totally divergent from all other stocks examined. Multivariate analysis of meristic features proves to be a useful method for identifying the extent of phenotypic variability among and within divergent stocks of rainbow trout. The observed meristic variability in test stocks of hatchery fish is seemingly genetically set within the limits previously described for native populations of rainbow trout.     

Overwinter feeding in rainbow trout

The contents of the stomachs of 38 rainbow trout stocked in Llyn Alaw, Anglesey, in August 1969 and caught between October 1969 and February 1970 were analysed. The fish were actively feeding on the bottom fauna throughout the winter and 21 of the stomachs were full or distended. The mean volume of the contents of the stomachs was 2–8 times greater than that of the contents of stomachs of similarly sized brown trout caught at the same time.     

Thrombocyte aggregation in rainbow trout

• 1.1. Thrombocytes from mature rainbow trout (Sahmo gairdneri) aggregated in vitro after addition of ADP, ATP, collagen, epinephrine, 5-hydroxytryptamine or thrombin to thrombocyte-rich plasma.
• 2.2. Thrombocyte aggregation was dose dependent and could be inhibited by preincubating the thrombocyte-rich plasma with adenosine, acetylsalicylic acid or prostaglandin E₁.
• 3.3. Thrombocytes released ADP and ATP when aggregated by 10 μM epinephrine. This release was blocked by 1 mM adenosine.
• 4.4. Electron microscopic observations of thrombocytes revealed them to contain numerous microtubules and electron-dense vesicles. In addition a possible shape change associated with thrombocyte aggregation was noted.

     

Activation of rainbow trout macrophages

Rainbow trout peritoneal macrophages were stimulated in vitro using Concanavalin A (Con A) and in vivo using formalin-killed Aeromonas salmonicida in Freund's incomplete adjuvant (FIA). Whether these cells had been activated was determined by the measurements of oxygen anions (NBT reduction), H₂O₂ production (oxidation of phenol red), RNA synthesis (³H-uridine incorporation), acid phosphatase activity and bactericidal activity.
In vitro -stimulated macrophages showed an increased NBT reduction and ³H-uridine incorporation over a range of Con A concentrations, compared with untreated control macrophages, but no detectable increases in H₂O₂ production or bactericidal activity were observed. On the other hand, in vivo -stimulated peritoneal cells showed increases in all the assays compared with FIA-elicited control cells, and were considered to have been activated.     

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.     

Habitat shifts in rainbow trout: competitive influences of brown trout

Summary We compared habitat use by rainbow trout sympatric (three streams) and allopatric (two streams) with brown trout to determine whether competition occurred between these two species in the southern Appalachian Mountains. We measured water depth, water velocity, substrate, distance to overhead vegetation, sunlight, and surface turbulence both where we collected trout and for the streams in general. This enabled us to separate the effects of habitat availability from possible competitive effects. The results provided strong evidence for asymmetrical interspecific competition. Habitat use varied significantly between allopatric and sympatric rainbow trout in 68% of the comparisons made. Portions of some differences refelected differences in habitats available in the several streams. However, for all habitat variables measured except sunlight, rainbow trout used their preferred habitats less in sympatry with brown trout than in allopatry if brown trout also preferred the same habitats. Multivariate analysis indicated that water velocity and its correlates (substrate particle size and surface turbulence) were the most critical habitat variables in the interaction between the species, cover in the form of shade and close overhead vegetation was second most important, and water depth was least important.     

A pepsinogen from rainbow trout

1. A pepsinogen, Ia on the basis of its electrophoretic mobility, from rainbow trout stomach, has an optimum pH near 2 for activation. 2. The cognate pepsin is denatured at pH values above 7, in contrast to the zymogen, which is slightly more alkali-stable. It has an optimum pH of 3 for proteolysis of denatured hemoglobin. 3. The intrinsic reactivity of the zymogen and pepsin (rates of activation and of proteolysis, respectively) are quite high, but as they operate at the environmental temperature of the fish, are remarkably similar to rates of activation and proteolysis by mammalian pepsinogens and pepsins.     

Force frequency relation in the myocardium of rainbow trout

Summary Isolated heart ventricular preparations from rainbow trout were electrically stimulated to contraction. Following a temporary change in stimulation rate from 0.2 Hz to a higher value, the force fell to a minimum after which it increased and levelled off. Upon the return to 0.2 Hz a further transient increase in force appeared. The latter two responses were stimulated by an increased extracellular K⁺, which is known to inactivate the Na⁺ channel. The initial negative inotropic effect, in contrast to the two subsequent positive effects, was associated with a parallel decrease in amplitude of the action potential measured in 15 mM K⁺, used as an index of the Ca²⁺ influx. One micromolar (1 M) ryanodine did not affect either the negative or the positive responses due to an increase in stimulation rate, but depressed the force developed after prolonged periods of rest. Ten micromolar (10 M) adrenaline strongly inhibited the positive effects of an elevation of frequency. An elevation of extracellular Na⁺ from 141 to 166 mM had a similar effect. In conclusion, the positive effects occurring in 15 mM K⁺ do not seem to depend on the initial Na⁺ current. They may nevertheless depend on changes of the cellular Na⁺ balance as suggested by the effects of adrenaline, K⁺ and Na⁺. The functional role of the sarcoplasmic reticulum is unclear.     

Extracellular microtubule-like structures in the retina of the rainbow trout

Summary Extracellular microtubule-like structures (MLS) are described in the retina of the rainbow trout. They appear about 30 to 40 days after hatching, when the yolk-sac is consumed and the animal begins to swim and to nourish actively. They fill a widely branched system of extracellular clefts and spaces, and connect different cells and cell types, especially outer horizontal cells and bipolar cells. The MLS are not affected by the vinca alcaloid vincristine, although this drug penetrates into the MLS-filled space, as has been shown by the formation of intracellular, vincristine-induced tubulin paracrystals. The MLS are compared with other extracellular tubular structures described in other animal tissues. Their functional significance remains unclear.     

Production of androgenetic diploid rainbow trout

Haploid androgenesis was induced in rainbow trout (Salmo gairdneri) when eggs were irradiated with 60Co gamma radiation prior to fertilization. Diploidy was restored to the androgenetic haploid zygotes by suppression of first cleavage division using hydrostatic pressure. Peak survival in the androgenetic diploid lots (32.5-38.9 percent of control) occurred when a pressure shock of 9000 pounds per square inch lasting from one to three minutes was applied to the eggs 345 minutes post-fertilization. Chromosomal analysis confirmed diploidy in the androgenetic individuals and suggested that YY rainbow trout are viable to at least the "eyed stage" of development. Inheritance patterns at two loci confirmed all-paternal inheritance. The relatively high yields of completely homozygous androgenetic rainbow trout and the potential for the use of androgenesis in the production of inbred lines and in genetic studies indicate that androgenesis may become a valuable tool in fish research and breeding.     

Glucose 6-phosphate dehydrogenase in rainbow trout

Electrophoretic analysis of glucose 6-phosphate dehydrogenase from liver and blood of rainbow trout revealed a complex series of bands, which could differ between fish. The partial interconvertible nature of these bands was demonstrated with enzyme that had been incompletely inactivated at pH 8.4. In a single population of 40 fish, a homozygote and a heterozygote for an electrophoretic variant allele were found. We suggest that G6PD in rainbow trout liver and blood is determined by two alleles at a single locus, with posttranslational modification responsible for the complex electrophoretic patterns seen. The basis for this variation appears to be NADH binding to the protein molecule. Another variant and other properties of the enzyme are described.Supported in part by the State of California Department of Mental Hygiene and by USPHS Grants GM-15253, HD-04612, HD-00315, HD-05615, and HL-15125. One of us (S.D.C.) was a Special Postdoctoral Fellow of NIAMD (No. 1F03AM-40, 329-01) during part of this work.     

Arterio-venous anastomoses in rainbow trout gill filaments

Summary The origin of arterio-venous anastomoses, connecting the efferent filament artery (EFA) with the central venous sinus (CVS) of gill filaments can be well discerned by scanning electron microscopy in the rainbow trout. Corresponding vessels between the afferent filament artery and the CVS could not be detected with the techniques applied. AVA-specific endothelial cells are characterized by their bulky shape and their microvillous surface. The general morphology of AVA's in Salmo gairdneri is very similar to that of AVA's in Tilapia mossambica (Vogel et al., 1974) but they are much longer in the trout. No filament whorls have been encountered in AVA endothelia of Salmo gairdneri.This study is dedicated to Prof. Dr. W. Graumann, Director of the Institute of Anatomy, University of Tübingen, on the occasion of his 60th birthday. It was supported by the Deutsche Forschungsgemeinschaft     

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.     

Somatostatin inhibits growth of rainbow trout

Implantation of rainbow trout Oncorhynchus mykiss with somatostatin-14 (SS-14) for 20 days resulted in reduced food conversion as well as significant growth retardation compared to controls. Relative growth as mass was reduced by 20%, whereas relative growth by length was reduced by 45%. A single intraperitoneal injection of SS-14 reduced plasma levels of growth hormone (GH), insulin-like growth factor-1 (IGF-I) and insulin. SS-14 injection also reduced [³⁵S]-sulphate incorporation into gill cartilage compared to saline-injected fish. In addition, in vitro incubation of gill cartilage with SS-14 reduced [³⁵S]-sulphate incorporation in a doserelated manner. These results indicate that SS-14 inhibits growth of rainbow trout and suggests that SS-14, in addition to influencing GH, may play an extra-pituitary role in the modulation of the GH-IGF-I axis.     

Antibody structural variation in rainbow trout fluids

Rainbow trout (Oncorhynchus mykiss) were immunized with trinitrophenylated-keyhole limpet hemocyanin (TNP-KLH) and the redox structure of induced anti-TNP antibodies from the serum, mucus, egg and ovarian fluid was examined. In conducting these studies it was determined that all TNP-specific antibody from each source possessed the mAb-specific H chain (1-14) epitopes, which facilitated the direct structural analysis of the induced antibodies. A protocol was developed which ensured complete adsorption of all specific anti-TNP antibody from each fluid. Together these protocols permitted the unbiased compositional analysis of all redox forms of the anti-TNP antibodies from each source. All antibodies, regardless of source, possessed the same molecular mass, characteristic of the trout tetramer (800 kDa). It was found that specific antibody titers were significantly higher in male than female trout, while the degree of disulfide polymerization was relatively invariant in male antibodies, while being highly variable in female antibodies. Within the females, no distinctively different redox ratios were between antibodies isolated from sera, ovarian fluid or eggs: however, mucus antibodies possessed a unique redox structure consisting of halfmeric constituents that were not observed in antibodies from other fluids.