Some functional consequences of partial hepatectomy in rainbow trout (Salmo gairdnerii)

A partial hepatectomy (an average of 36% of hepatic mass removed) was performed in rainbow trout. Thirty days after this partial hepatic removal, the liver had recovered its initial weight. During regeneration the remaining liver was unable to maintain normal blood levels of protein, cholesterol and, partially, lipids which decrease after surgery. The results obtained show that functional and liver weight regeneration proceed at different rates throughout a given time course, weight recovering faster than complete functional restoration.     

Protein digestion and ion concentrations in rainbow trout (Salmo gairdnerii Rich.) digestive tract in sea- and fresh water

• 1.1. Rainbow trout maintained in fresh water or Actapted to sea-water for 24 hr were fed casein-based dry diet. After feeding, fish were kept in fresh water (FW) or transferred to artificial sea-water (SW) and sacrificed after 10 or 20 hr.
• 2.2. The digestive tract was separated into five parts: stomach, pyloric caeca region, middle intestine and two equal lengths of rectum.
• 3.3. The content of these parts was analysed for ions Na⁺, K⁺, Cl⁻, Mg²⁺ and for free, peptide and total amino acids.
• 4.4. In the fish stomach all ions, with the exception of Ca²⁺, indicate drinking of sea-water. In the pyloric caeca region Na⁺ appears to be efficiently absorbed in SW fish but influxed in FW fish. In the rectum of SW fish K⁺ appears to be reabsorbed but Na⁺ concentrated in faeces.
• 5.5. Free amino acid concentrations were always higher in gut lumen of SW than in FW fish in respect to time after feeding and portion of intestinal content. Free amino acids constitute at most 7.4–8.7% of total amino acids in the content of pyloric caeca region.
• 6.6. Peptide amino acids, being mostly di-, tri- and tetra-peptides, increased in stomach content from 14.7 to 28.4% of the total, from 6 to 10 hr after a meal in SW fish. Peptide amino acids constituted 80.3–89.0% of total amino acids in intestinal content of the pyloric caeca region. These peptide portions decreased in the mid-intestine (47.5–52.5%) and increased again in the rectum (73.6–76.0%).
• 7.7. It was concluded that in rainbow trout fed in both sea- or fresh water, ion concentrations do not seem to interfere with protein digestion and nutrient absorption in alimentary tract.

     

Effects of sampling on blood parameters in the rainbow trout, Salmo gairdneri Richardson

The effects of sampling and short-term storage of blood samples on the blood parameters of rainbow trout were evaluated by comparing values obtained from resting fish sampled via cannulae and from fish sampled by cardiac puncture. Sampling stress causes an increase in haematocrit value and a decrease in mean cellular haemoglobin concentration, indicating red cell swelling. These changes are aggravated by consecutive storage of samples. Also, blood ionic balance is affected. The K⁺ concentration of plasma increases and plasma Cl⁻ concentration decreases owing to sampling. During storage the plasma K⁺ concentration decreases far below resting levels in samples taken by cardiac puncture, whereas plasma Cl⁻ level returns to pre-stress levels. Owing to the sampling- and storage-induced changes in blood parameters, care must be taken to ensure that similar sampling procedure is employed throughout to allow reliable comparisons between groups to be made.     

The rainbow trout Salmo gairdneri (Rich.) fishery of Lake Titicaca

Rainbow trout were introduced to Lake Titicaca in 1942. A commercial trout canning operation started in 1961 but terminated in 1970. Data for this study were collected in 1966 and 1967, with the object of examining the life history, biology, and commercial fishery of Titicaca rainbow trout. Trout were caught commercially and experimentally by gillnets in different parts of the lake.
Lake Titicaca lies across the border of Peru and Bolivia at 3212 m above sea level. The physico-chemical characteristics of the lake appear ideal for self-sustaining populations of rainbow trout. Growth was constant throughout the year, and was good in relation to growth rates of rainbow trout in other parts of the world. Spawning took place in the tributaries in the winter. Recruitment to the fishery occurs in 7.62 cm stretch mesh gillnets at about 27 cm fork length.
The total annual commercial catch increased to 500 metric tons in 1965 before subsequently decreasing. The simplest explanation for the decline in total catch would be the increase in fishing mortality due to increased fishing effort, although it is possible that the decline in water level has had some effect. It appeared possible that the lake could sustain an annual catch of about 350 tons.     

Biosynthesis of rainbow trout (Salmo gairdnerii) hemoglobins in vitro

Cell free systems were established to analyze the biosynthesis of trout hemoglobins I, II and III. HbI, II and III were synthesized in trout erythroid cell lysates as well as in a mRNA dependent rabbit reticulocyte lysate supplemented with trout erythroid cell polyA-RNA. The newly synthesized hemoglobins apparently contained the N alpha-acetyl modification at their alpha-chain amino terminals since they co-migrated with carrier trout hemoglobins that are known to contain the modification. This observation suggests that the acetylation is determined by the information encoded in the mRNA.     

Lysosomal damage under nitrite intoxication in rainbow trout (Salmo gairdneri Rich.)

1. In Salmo gairdneri specimens exposed to 450 micrograms/l NO2-N (nearly 36 hr LC50) for various exposure times (12-72 hr) some parameters of liver lysosomal function were examined. 2. In vivo both total proteolytic activity and single protease activities were inhibited, the inhibition increasing with the lengthening of exposure time. In vitro no analogous effect was observed. 3. Lysosomal membranes showed an increased fragility correlated with the physiological conditions of treated animals. 4. Data were considered as the results of a nitrite mediated effect on functional and structural proteins.     

Organization of the histone genes in the rainbow trout (Salmo gairdnerii)

Summary Twelve clones containing histone genes were isolated from a genomic trout library constructed in the vector Charon 4A. Each of the clones was found to contain a conserved 10.2-kb Eco RI fragment that contained one copy of each of the histones in the order H4-H2B-H1-H2A-H3, all of which are transcribed from the same strand. Genomic Southern blots indicate that these clusters are representative of the vast majority of the histone genes in the trout. Tandemly linked clusters were not found. Approximately 145 copies of this cluster are present in a trout sperm cell. Sequence analysis has shown the genes to be without introns and to show strong selection for codons ending in C or G. Consensus signals similar to those found in other histone genes are present in the flanking regions.     

Effects of experimental anemia on the ATP content and the oxygen affinity of the blood in the rainbow trout (Salmo gairdnerii)

Blood oxygenation properties have been investigated in rainbow trout, 1 and 48 hr after an approximately 25% loss of blood. In both cases the hematocrit was nearly halved. The ATP/Hb4 ratio was significantly increased by 35 and 46% after 1 and 48 hr, respectively. The P 1/2 value (at pH 7.7 and 20 degrees C) was significantly raised, by about 2 mmHg, in both cases. After 48 hr, this decrease in the blood-oxygen affinity and the increase in the red-cell ATP content were significantly positively correlated. The mean corpuscular hemoglobin concentration (MCHC) value was never significantly changed. The pH was decreased by about 0.1 unit after 1 hr but normal values were found after 48 hr. It is suggested that these variations might be of adaptative value for fish in conditions of normal environmental pO2.     

The effect of exercise on plasma cortisol and blood sugar levels in the rainbow trout, Salmo gairdnerii Richardson

Preliminary experiments were performed to determine the diurnal variation in cortisol, using trout which had been cannulated three days previously. These results indicated that cortisol levels were reasonably stable between 10.00 and 18.00 hours, thus permitting experimentation during this period without diurnal fluctuations masking the cortisol response. Uncannulated fish were exercised in a flume for 2 h at 1, 2.6 and 5 bl s^-1 and plasma samples taken from groups of five animals at 15, 30, 60 and 120 min after the start of exercise and at 1½, 12 and 24 h after the exercise ceased. The cortisol levels in all cases were elevated after 15 min, but the magnitude of the elevation increased with swimming speed. At 1 bl s^-1 the cortisol levels increased from 76.4 (± 20.4) to 129.2 (± 20.4) ng ml^-1 [mean (± s.d. )]. At 2.6 bl s^-1 the increase was from 72.4 (± 17.1) to 254.4 (± 34.4) ng ml^-1 and at 5 bl s^-1 the increase was from 69.5 (± 27.5) to 326.4 (± 39.0) ng ml^-1. The cortisol levels were stable over the exercise period and all groups recovered to baseline levels after 24 h, though the sample taken 12 h after the termination of exercise was elevated due to regular nocturnal increases in cortisol levels. There were no dramatic changes in blood sugar levels during and after exercise at 1 and 3.2 bl s^-1.     

Some blood parameters of the rainbow trout (Salmo gairdneri Richardson)

Some of the blood constituents of male, female and immature rainbow trout of the Shasta variety, maintained in known environmental and dietetic conditions, were examined and the results statistically treated. The parameters for male and female trout were similar, only the erythrocyte count exhibiting a significant difference. Large but expected differences were evident between the parameters for mature and immature fish.     

Some blood parameters of the rainbow trout (Salmo gairdneri Richardson)

Fifty rainbow trout of the Kamloops strain were examined for 12 haematological parameters: erythrocyte sedimentation rate, haemoglobin, packed cell volume, erythrocyte count, erythrocyte diameters, mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, leukocyte count, differential leukocyte count, plasma total protein and plasma glucose concentration. The fish had been held under known environmental and dietetic conditions, and at the time of sampling were 14 months old. The majority of results for erythrocyte sedimentation rate, haemoglobin, packed cell volume, erythrocyte count, erythrocyte diameters, total protein and differential leukocyte count fell within narrow ranges. The total leukocyte counts and glucose levels were more widely spread. The results are discussed and compared with those already published for Idaho and Shasta strains. It is impossible to say whether the differences that were observed between Kamloops and these other varieties were due to strain alone, since other variables were present. Some problems associated with establishing normal ranges for these parameters in fish are discussed.     

The development of catecholamines in embryos and larvae of the rainbow trout (Salmo gairdneri Rich.)

Catecholamines are present in the late embryonal and early larval developmental stages (alevin) of the rainbow trout. Changes in the alevin behaviour can be related to the catecholamine concentrations.     

A literature review of the blood chemistry of rainbow trout, Salmo gairdneri Rich.

The literature on the blood chemistry of rainbow trout, Salmo gairdneri Rich., is reviewed from the aspects of experimental methods, electrophoresis, normal values, environmental and endogenous factors including toxic substances and diseases.     

Bioconversion pathway of astaxanthin into retinol2 in mature rainbow trout (Salmo Gairdneri Rich.)

• 1.1. Carotenoid and retinoid forms were analysed by HPLC in various tissues of mature rainbow trout fed for 11 months (7–9°C) with astaxanthin (50 and 100 mg/kg diet) or canthaxanthin (100 mg/kg diet).
• 2.2. Decreasing concentrations of canthaxanthin, echinenone and β-carotene, but no retinol₁, were found in the liver and skin of canthaxanthin-fed fish.
• 3.3. Higher retinol₂ concentrations were found in ovaries and testes of astaxanthin-fed fish compared to canthaxanthin and control groups.
• 4.4. A new metabolic pathway for direct conversion of astaxanthin into retinol₂ in gonads is proposed.

     

Branched chain alpha-keto acid dehydrogenase in tissues from rainbow trout (Salmo gairdnerii)

Mitochondria isolated from skeletal red muscle of rainbow trout (Salmo gairdnerii) have remarkably high activity of branched chain alpha-keto acid dehydrogenase as measured with alpha-keto isocaproic acid as substrate. The activity of the dehydrogenase increases several-fold after preincubation of the mitochondria with an uncouple and oligomycin. The accumulation of the first product, isovaleryl-CoA is strongly stimulated by high concentrations of CoASH. In the crude mitochondrial lysates we have used, an unknown compound accumulates with time, during incubation with alpha-keto isocaproic acid, CoASH and NAD. The compound, probably a CoA derivative, is more hydrophobic than isovaleryl-CoA.