Muscle Tissue Of Rainbow Trout Research Articles

Method for obtaining ecological products from rainbow trout Oncorhynchus mykiss farming

In aquaculture, the period of active development of aquatic organisms is considered one of the most important for the formation of potential in the future. The issue of using natural components when growing aquatic organisms and feeding young fish is given special attention. This research investigated Spirulina (25%) + Vermiculture (50%) + Hermetia illucens (25%) as an additional source of functional active substances and protein that affect the body performance of rainbow trout in early ontogenesis. All objects were cultured in a special bioreactor, which was a component of the recirculating aquaculture model system as well as in the laboratory, where an installation was made for cultivating natural food. The results of the scientific and practical part of the work showed that after the end of the experiment, body weight was higher in the experimental fish by 7.2% than in the control group. This article presents the results of feeding rainbow trout as one of the cases of improving the morpho-functional and biochemical composition of the blood of this species: an increase in the total number of red blood cells by 11.0%, hemoglobin content by 9.7%, total protein at 22.7%, albumin by 24.2%, and creatinine by 15.5%, compared with the control group. The presented positive changes in the functional status of the rainbow trout organism were in harmony with the parameters of body weight, as well as histological indicators. Histological indicators of the liver and muscle tissue of the fish supplemented the obtained positive result of the influence of natural and active components of the feed. Feeding fish according to the scheme in the experimental group promotes the formation of layers of special adipose tissue in the endomysium. The total amount of the stromal component in the muscle tissue of rainbow trout was 25% of the mass of the entire tissue. The control group showed that the muscle fibers were polygonal in cross section, separated from each other within the bundle by delicate layers of endomysium. When using a standard feeding regimen (control group), the stromal component is a moderately expanding structure that replaces the space between the fibers. The experimental group had the most significant indicators. The intensification of individual aspects of homeostasis achieved with the help of feed components (experimental group) promotes the growth of muscle fibers in thickness due to the formation of new fibrils, but not an increase in the proportion of sarcoplasm (watery meat). As a result, neurohumoral regulation and substance synthesis processes improved in the fishes’ body, which helps to improve ontogenesis rates. The presented ingredients in the diet of rainbow trout are natural stimulants of metabolic processes and sources of nutrients. The method allows aquaculture to be defined as being as close as possible to “environmentally safe”. The next stage will be a comprehensive analysis of the qualitative and quantitative characteristics of rainbow trout meat under the influence of the feed factor.

Effectiveness evaluation of the infl uence of protein concentrates on the chemical composition of fish meat

Due to the high demand, cost, growing shortage and low quality of fi sh-meal, there is a constant search for affordable alternative feed raw materials in feeding aquaculture fi shing grounds. The use of high-protein products of plant origin is the most effective option for replacing fi sh-meal in fi sh feed. The purpose of the work was to evaluate the eff ectiveness of the infl uence of protein concentrates on the chemical composition of rainbow trout meat. Testing of compound feed for rainbow trout, the formulation of which included high-protein feed concentrates, was carried out on the basis of IP Kalmykova I. O. and under the conditions of the Research Center “Breeding valuable sturgeon breeds” at the Volgograd State Agrarian University. It was found on base of the results obtained that more intensive growth was observed in the groups in which the mustard protein-containing feed concentrate Gorlinka was introduced into the feed formulation with partial or complete replacement of sunfl ower meal. Here, the increase in the total and average daily live weight gain was noted by 2,83–6,93 % and by 1,62–1,68 %. The use of the Agro-Matic concentrate during the period of the experiment had a positive eff ect on the growth dynamics of rainbow trout, increasing productivity indicators. Thus, live weight indicators increased by 1,29–4,15 %, daily gain indicators increased by 1,44–4,46 % relative to individuals receiving compound feed with fi sh-meal. When studying the chemical composition of trout meat with the addition of Gorlinka concentrate to the feed formulation in the experimental groups, the increase in protein content was revealed by 0,13–0,41 abs.%, inorganic matter by 0,04–0,12 abs.%, also the total amount of amino acids increased by 0,18–0,46 abs.%, while the fat content on the contrary decreased by 0,05–0,17 abs.% compared to the control. In the experimental trout groups, when introducing the Agro-Matic protein concentrate into the diet instead of fi shmeal the protein content increased by 0,03–0,40 abs.%, inorganic matter by 0,08–0,24 abs.%, total amino acids increased by 0,11–0,58 abs.%, there was a slight decrease in the amount of fat by 0,10–0,36 abs.% compared to the 1st control group. The use of protein concentrates has a positive eff ect on the qualitative composition of the muscle tissue of rainbow trout by increasing the protein content and the amount of essential amino acids in the muscle tissue of individuals surpassing the 1st control group in key indicators.

BIOMARKERS OF LIPID AND PROTEIN OXIDATION IN THE MUSCLE TISSUE OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM) TREATED IN VITRO WITH ROOT AND STEM EXTRACTS OF GREATER CELANDINE (CHELIDONIUM MAJUS L.)

The main aim of the present study was to evaluate the oxidative stress biomarkers [TBARS, carbonyl derivatives of oxidative modification of proteins (OMP), total antioxidant capacity (TAC)] in the muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) after in vitro incubation with the root and stem extracts derived from greater celandine (Chelidonium majus L., CM) (at final concentrations of 5 and 2.5 mg/mL) collected in South Park in Słupsk in the Pomeranian Province (northern part of Poland). The current study demonstrated the increase in TBARS levels after in vitro incubation of rainbow trout muscle tissue with stem and root extracts of CM at a final concentration of 5 mg∙mL-1 compared to untreated control samples. There was a statistically significant increase in TBARS levels compared to controls. We obtained similar results after in vitro incubation with root and stem extracts of CM at a final concentration of 2.5 mg∙mL-1 with rainbow trout muscle tissue, where we also observed a statistically non-significant increase in TBARS levels. There was a decrease in the levels of aldehydic derivatives and ketonic derivatives of OMP in muscle tissue after incubation with extracts from roots and stems of CM at final concentrations of 5 mg∙mL-1 compared to untreated controls. There was a decrease in the levels of aldehydic and ketonic derivatives of OMP in muscle tissue after incubation with extracts from roots and stems of CM at final concentrations of 2.5 mg∙mL-1 compared to untreated controls. TAC levels in rainbow trout muscle tissue after in vitro incubation with extracts of CM roots and stems at final concentrations of 5 and 2.5 mg∙mL-1 were not statistically significantly increased. The present study investigated the antioxidant potential of CM. Extracts from CM roots and stems exert their activity by inhibiting protein damage.

Physiological, biochemical, and histological changes in trout muscles as a result of white lupine inclusion in the diet structure

The work evaluated the effect of white lupin on the physiological, biochemical, and histological parameters of rainbow trout. The data of water chemical analysis, biochemical and histological analysis of rainbow trout muscles are presented. The results of the experiment indicate more pronounced positive results in the experimental groups, the average live weight of trout at the end of the studies in the 2nd experimental group was 3.7% higher relative to the control group. The average live weight of the 3rd group was 18.5% higher and that of the 4th group was 7.4%. At the end of the studies, an increase in muscle mass was observed in group 2 by 1.5% more than in the control group, group 3 – 18.8% and in the 4 experimental group – 12.8%, respectively. According to the results of biochemical analysis of muscle tissue, an increase in protein content in the experimental groups was established, in 2 experimental group by 0.2%, in 3 experimental group – 3.59%, and in 4 experimental group – 3.11%. The fat content in the muscle tissue of rainbow trout of the experimental groups decreased by 0.46% in 2 experimental group, 1.0% in 3 experimental group, and 0.96% in 4 experimental group. Therefore, the use of white lupin in the diet as a high-protein component affects the reduction of body fat in rainbow trout and contributes to an increase in protein content. Histological analysis of the white muscles of the control and experimental groups of trout showed moderate separation of muscle fibers and integrity of myofibrils. The striation of the transverse muscle was well pronounced. The experiment established a positive effect on its productivity, the biochemical composition of muscle tissue, and the quality of the products obtained.

The effect of the feed additive «Kormogran selen-3» on fish breeding, morphometric indicators and marketable qualities of Rainbow trout

An experimental cultivation of rainbow trout was carried out using the selenium-containing feed additive «Kormogran Selen-3». According to a number of morphometric parameters, there were no significant true differences between the experimental and control groups, however, an intensification of fat metabolism in the trout of the experimental group was established, which slowed down the process of accumulation of intracavitary fat by individuals. This caused some lag in the process of total mass accumulation and some decrease in fish-breeding and biological indicators. At the same time, there was no decrease in the rate of linear growth and overall development of fish. The main accumulation of selenium occurred in the liver, where its content increased by 613,9 times (from 1112 to 15363 μg/kg). At the same time, the content of this element in white muscles increased by 5,2 times, and in red – by 2 times, which indicates the possibility of intravital enrichment of muscle tissue of rainbow trout with selenium. The analysis of the quality of commercial fish and its nutritional value showed the advantages of the experimental batch in comparison with the control of the yield of edible parts, organoleptic evaluation of smoked products, which at the same time can be attributed to a functional product as a source of selenium.

Fatty Acid Composition and mRNA Expression of Fatty Acid Binding Protein Genes (fabp3 and fabp6) in Rainbow Trout Fed Camelina Seed Oil (Camelina sativa)-Based Diets

Vegetable lipids such as camelina oil (Camelina sativa) are used as alternatives oil sources to fish oil in aquafeeds. In this study, we determined fatty acid-binding protein 3 (fabp3) and fatty acid-binding protein 6 (fabp6) gene expression and fatty acid composition in the liver and muscle tissue of rainbow trout fed different amounts of dietary camelina seed oil [100% (CO100), 67% (CO67), and 37% (CO33)]. Palmitic acid and oleic acid were identified as the most abundant saturated and monounsaturated fatty acids, respectively, in both tissues across all experimental groups. The highest levels of n-6 polyunsaturated fatty acid (Σn- 6 PUFA) were found in the first biopsy (15th day) taken from fish fed a diet of CO100, while the highest Σn–3 PUFA level was found in the third biopsy (45th day) taken from the same group. The FO100 (fish oil) diet was found to have the highest Σn-3 / n-6 ratio, as well as the highest levels of eicosapentaenoic acid and docosahexaenoic acid. In general, the fatty acid composition of the fish reflected that of their respective diets. The expression of fabp3 and fabp6 genes in the muscle of fish fed camelina seed oil were not significantly different from control group. However, fabp3 gene expression of liver of FO100 group was found to have significantly higher than CO67 and CO33. A difference in hepatic fabp6 gene expression was also noted in the FO100 group, but was not found to be statistically significant. Growth parameters and survival rate were not affected after the 45 days feeding trial. These results suggest that camelina seed oil can be used as an alternative to fish oil in rainbow trout diet.

Dose-Dependent Changes in the Levels of Oxidative Stress Biomarkers in the Muscle Tissue of Rainbow Trout (Oncorhynchus mykiss Walbaum) after In Vitro Treatment by Extracts Derived from Stalks and Roots of Great Celadine (Chelidonium majus L.)

Consistent with our previous studies, we continue to evaluate the antioxidant potential of representatives belonging to the Papaveraceae family collected from the northern part of Poland using a muscle tissue model of rainbow trout (Oncorhynchus mykiss Walbaum). Therefore, in the present study, oxidative stress biomarkers [2-thiobarbituric acid reactive substances (TBARS), protein oxidative modification carbonyl derivative content, total antioxidant capacity (TAC)] were used to evaluate the antioxidant activity of stalk and root extracts of Chelidonium majus L. (CM) at doses of 5 mg·mL-1, 2.5 mg·mL-1, 1.25 mg·mL-1, and 0.63 mg·mL-1. Muscle tissue homogenates of rainbow trout were used in this study. Phosphate buffer was used as a positive control. After incubation of the mixture at 25 °C for 2 h with continuous mixing, samples were used for biochemical studies. Results of our study revealed that a dose of CM extracts of 0.63 mg·mL-1 showed the highest antioxidant activity in the muscle tissue of rainbow trout. The extracts derived mainly from the roots of CM collected from rural areas were effective in reducing the levels of oxidative stress biomarkers by reducing lipid peroxidation markers, which may suggest that the active substances such as alkaloids (chelidonine, sanguinarine, berberine), flavonoids, phenols in these plants can effectively protect the membrane structures in muscle cells of salmonids. We also observed statistically significant reductions in levels of both aldehydic and ketonic derivatives of oxidatively modified proteins in muscle tissue of rainbow trout after incubation with CM extracts at this dose compared to the controls. The comparison of these results shows that CM extracts can effectively inhibit protein damage by scavenging free radicals and/or activation of antioxidant defenses. The secondary metabolites of CM, i.e. polyphenols and alkaloids, are most likely responsible for this effect. Using doses of 5 mg·mL-1, 2.5 mg·mL-1, and 1.25 mg·mL-1 of both root and stalk extracts in vitro study, statistically significant increases in levels of TBARS and OMP were observed. Screening of species belonging to the family Papaveraceae for other biological activities, including antioxidant activity, is essential and may be effective in the search for preventive measures in the pathogenesis of diseases caused by oxidative stress in human and veterinary medicine.

ДОЗОЗАЛЕЖНІ ЗМІНИ БІОМАРКЕРІВ ОКИСНЕННЯ ЛІПІДІВ ТА БІЛКІВ У М'ЯЗОВІЙ ТКАНИНІ РАЙДУЖНОЇ ФОРЕЛІ (ONCORHYNCHUS MYKISS WALBAUM) ПІСЛЯ ІНКУБАЦІЇ IN VITRO З ЕКСТРАКТАМИ ЧИСТОТІЛУ ВЕЛИКОГО (CHELIDONIUM MAJUSL.)

Consistent with our previous studies, we continue to evaluate the antioxidant potential of representatives of the Papaveraceae family collected from the northern part of Poland on the model of muscle tissue of rainbow trout. Therefore, in the current study, oxidative stress biomarkers [2-thiobarbituric acid reactive substances (TBARS), aldehydic and ketonic derivatives of oxidatively modified proteins (OMP), and total antioxidant capacity (TAC)] were used to evaluate the antioxidant activity of extracts derived from stalks and roots of great celandine (Chelidonium majus L., CM) at a final dose of 5 mg/mL, 2,5 mg/mL, 1,25 mg/mL and 0,63 mg/mL. Homogenate of muscle tissues derived from rainbow trout was used in this in vitro study. Phosphate buffer was used as a positive control (blank). After incubation of the mixture at 25°C for 120 min with continuous mixing, samples were used for biochemical studies. Our studies have shown that the use of extracts at a final dose of 5 mg/ml and 2.5 mg/ml resulted in a statistically significant increase of lipid peroxidation biomarkers (TBARS levels) in the muscle tissue of rainbow trout. The final dose of extract 1.25 mg/ml caused a statistically significant increase in the levels of aldehydic and ketonic derivatives of OMP, and this is reflected when measuring the levels of TAC. On the other hand, the use of extracts at a final dose of 0.63 mg/ml derived from both roots and stems of CM resulted in statistically significant reduced levels of TBARS, as well as aldehydic and ketonic derivatives of OMP in the muscle tissue of rainbow trout after in vitro incubation. The comparison of these results showed that CM extracts can effectively inhibit the production of oxidatively modified carbonyls by scavenging free radicals. The secondary metabolites of CM, i.e. polyphenols, are most likely responsible for this effect. Screening of species of the family Papaveraceae for other biological activities, including antioxidant activity, is essential and may be effective in the search for preventive measures in the pathogenesis of some diseases, as well as in the prevention and treatment of some disorders in veterinary and medicine. Keywords: rainbow trout (Oncorhynchus mykiss Walbaum), muscle tissue, oxidative stress, 2-thiobarbituric acid reactive substances (TBARS), aldehydic and ketonic derivatives of oxidatively modified proteins (OMP), total antioxidant capacity (TAC).

BIOMARKERS OF OXIDATIVE STRESS IN THE MUSCLE TISSUE OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM) AFTER IN VITRO TREATMENT BY EXTRACTS DERIVED FROM STALKS AND ROOTS OF GREATER CELANDINE (CHELIDONIUM MAJUS L.)

Consistent with our previous studies, we continue to evaluate the antioxidant potential of Greater celandine (Chelidonium majus L), a representative of the Papaveraceae family, collected from northern Poland using the model of muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum). Therefore, in the present study, oxidative stress biomarkers [2-thiobarbituric acid reactive substances (TBARS), protein oxidative modification carbonyl derivative content, total antioxidant capacity (TAC)] were used to evaluate the antioxidant activity of extracts (final concentration 5 mg/mL) derived from stems and roots of C. majus. Rainbow trout muscle tissue was used in this study. Phosphate buffer was used as a positive control (blank). The results of the current study showed that stem and root extracts exhibited cytotoxic effects on cellular structures of muscle tissue by increasing the level of the lipid peroxidation biomarkers. These results suggest the possibility of using C. majus extract at 5 mg/mL as a source of pro-oxidant compounds and warrant further studies to evaluate their therapeutic potential. Levels of aldehydic and ketonic derivatives of oxidatively modified proteins and total antioxidant capacity were not significantly changed after in vitro incubation with the extracts derived from stalks and roots of C. majus. Screening of species of the family Papaveraceae for other biological activities, including antioxidant activity, is essential and may be effective in the search for preventive measures in the pathogenesis of some diseases, as well as in the prevention and treatment of some disorders in medicine and veterinary.

Transcriptomic response of rainbow trout (Oncorhynchus mykiss) skeletal muscle to Flavobacterium psychrophilum

Flavobacterium psychrophilum is the etiologic agent of rainbow trout fry syndrome (RTFS). This pathogen infects a wide variety of salmonid species during freshwater stages, causing significant losses in the aquaculture industry. Rainbow trout (Oncorhynchus mykiss) infected with F. psychrophilum, presents as the main external clinical sign ulcerative lesions and necrotic myositis in skeletal muscle. We previously reported the in vitro cytotoxic activity of F. psychrophilum on rainbow trout myoblast, however little is known about the molecular mechanisms underlying the in vivo pathogenesis in skeletal muscle.In this study, we examined the transcriptomic profiles of skeletal muscle tissue of rainbow trout intraperitoneally challenged with low infection dose of F. psychrophilum. Using high-throughput RNA-seq, we found that 233 transcripts were up-regulated, mostly associated to ubiquitin mediated proteolysis and apoptosis. Conversely, 189 transcripts were down-regulated, associated to skeletal muscle contraction. This molecular signature was consistent with creatine kinase activity in plasma and oxidative damage in skeletal muscle. Moreover, the increased caspase activity suggests as a whole skeletal muscle atrophy induced by F. psychrophilum. This study offers an integrative analysis of the skeletal muscle response to F. psychrophilum infection and reveals unknown aspects of its pathogenesis in rainbow trout.

Evaluation of Heavy Metals Concentration and Its Consumption Risk in Trout Fish (Oncorhynchus Mykiss)

Background: Nowadays, the pollution of aquatic ecosystems caused by entry of heavy metals is an issue that makes it essential to check the wholesome of the aquatic animals that are consumed by human. When these metals enter the canvas of aquatic organisms, cause tension due to bioavailability, and their toxicity leads to teratogenic, mutagenic and carcinogenic effects in living organisms Methods: Thirty rainbow trout were prepared from each fishing farm pond which are located in Sanandaj (Nanale Village) and Kamyaran (Diwaznaw Village). Then, samples were prepared using acid digestion method in the laboratory and the concentration of these metals was measured using atomic absorption spectrometer (Phonix 986). The achieved data were analyzed using SPSS software.. Results: The average concentration of the copper in liver and muscle tissues was 1. 53 and 0.15, for magnesium 3.7 and 7.57, for iron 0.28 and 0.6, for zinc 4.52 and 1.05, and for Nickel was 0.04 and 0.03 micro grams per a gram of fresh weight. The maximum daily consumption allowance was 888.7 grams for adults and 177.77 for children Conclusion: The average concentration of copper, iron, zinc, nickel and magnesium in muscle tissue of rainbow trout compared to international standards, is slightly lower than that at current consumption rates, long-term health risks to consumers is realized.

Mineral content of muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum)

Mineral content of muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum)

Oxidative stress and antioxidant defence markers in muscle tissue of rainbow trout (Oncorhynchus mykiss) after vaccination against Yersinia ruckeri

Abstract Introduction: The goal of this study was to assess the influence of vaccination against enteric redmouth disease on oxidative stress biomarkers and antioxidant defence in the muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) vaccinated against Yersinia ruckeri in the first and second month after immunisation. Material and Methods: Healthy fish were vaccinated orally with inactivated whole cells of a virulent strain of Y. ruckeri. One and two months after immunisation the muscle samples were collected. Results: No significant difference was noted in lipid peroxidation level in either the first or second month after vaccination, while aldehydic and ketonic derivatives of oxidatively modified proteins (OMB) in the vaccinated group were significantly lower in the second month compared to those in the first month after vaccination (P < 0.05). The content of ketonic derivatives of OMB in muscles in the first month after immunisation was higher compared to untreated control. All these culminated in a depletion of glutathione peroxidase (GPx) activity and low level of total antioxidant capacity (TAC). Conclusion: Correlations between catalase activity and lipid peroxidation and TAC confirmed the pivotal role of catalase in antioxidant defence during immunisation. From a broader perspective, it is suggested that immunisation of fish with Yersinia vaccine is associated with induced free radical formation and oxidative stress. Free radicals would therefore be at least partially responsible for the induction of both humoral and cellular elements of the immunity and increased protective immunity against Y. ruckeri infection.

Influence of farming technology on bioaccumulation of calcium, magnesium and sodium in muscle tissue of rainbow trout (Oncorhynchus mykiss Walbaum) / Wpływ technologii chowu na biokumulację wapnia, magnezu i sodu w tkance mięśniowej pstrąga tęczowego (Oncorhynchus mykiss Walbaum)

Abstract Poland is one of the countries with limited water resources where water saving is recommended e.g. by improving aquaculture methods to use less water. The aim of the study was to determine the influence of water quality and aquaculture technology on bioaccumulation of calcium, magnesium and sodium in muscle tissue of rainbow trout. The study was performed in spring and autumn 2011 in two trout fish farms using different farming technologies: one with flow-through system and the other with water recirculation system. The farming technology had significant influence on magnesium and sodium in waste waters but did not affect the content of the minerals in muscle tissue of rainbow trout

Determination of histamine content in muscle tissue of rainbow trout (Oncorhynchus mykiss) during ice storage

In this study, the histamine concentration in the muscle tissue of whole rainbow trout (Oncorhynchus mykiss) was monitored during ice storage for a period of 18 days (0, 3, 6, 9, 12, 15 and 18th day). Results showed that the concentration of histamine increased linearly (P < 0.05) during ice storage (except the 18th day). Histamine was not detected at the first and third day of storage. The first detection of histamine was in the sixth storage day. Initial concentration of histamine was 1.09 μg/g and finally reached to 4.30 μg/g. The maximum histamine levels was reported to be below the Australian Food Standards Code (2001) safe level (200 mg/kg), and histamine levels were low even after 18 days of storage and remained below the Food and Drug Administration (2001) tolerance level during ice storage. It seems that the levels of histamine could be a suitable freshness indicator of rainbow trout during ice storage.

Mercury and selenium concentrations in muscle tissue of different species of predatory freshwater fish and correlation between these elements

Concentrations of total mercury and selenium were determined in 49 and 42 muscle tissue samples, respectively, of six species of predatory freshwater fish, dace (Leuciscus leuciscus), pike perch (Sander lucioperca), pike (Esox lucius), European catfish (Silurus glanis), rainbow trout (Oncorhynchus mykiss) and asp (Aspius aspius). Muscle selenium concentration did not correlate with the corresponding total mercury concentration (R 2 < 0.198) in all examined predatory fish species. There was an inverse correlation between the ratio Se/Hg content and the total mercury content in the muscle tissues of dace, pike perch, pike, European catfish and asp. The muscle tissue of rainbow trout exhibits a linear correlation between the ratio Se/Hg content and the total mercury content. The total mercury concentration of all examined samples did not exceed the hygienic limit for Hg for predatory fish.

Fibroblasts Express Immune Relevant Genes and Are Important Sentinel Cells during Tissue Damage in Rainbow Trout (Oncorhynchus mykiss)

Fibroblasts have shown to be an immune competent cell type in mammals. However, little is known about the immunological functions of this cell-type in lower vertebrates. A rainbow trout hypodermal fibroblast cell-line (RTHDF) was shown to be responsive to PAMPs and DAMPs after stimulation with LPS from E. coli, supernatant and debris from sonicated RTHDF cells. LPS was overall the strongest inducer of IL-1β, IL-8, IL-10, TLR-3 and TLR-9. IL-1β and IL-8 were already highly up regulated after 1 hour of LPS stimulation. Supernatant stimuli significantly increased the expression of IL-1β, TLR-3 and TLR-9, whereas the debris stimuli only increased expression of IL-1β. Consequently, an in vivo experiment was further set up. By mechanically damaging the muscle tissue of rainbow trout, it was shown that fibroblasts in the muscle tissue of rainbow trout contribute to electing a highly local inflammatory response following tissue injury. The damaged muscle tissue showed a strong increase in the expression of the immune genes IL-1β, IL-8 and TGF-β already 4 hours post injury at the site of injury while the expression in non-damaged muscle tissue was not influenced. A weaker, but significant response was also seen for TLR-9 and TLR-22. Rainbow trout fibroblasts were found to be highly immune competent with a significant ability to express cytokines and immune receptors. Thus fish fibroblasts are believed to contribute significantly to local inflammatory reactions in concert with the traditional immune cells.

Residue depletion of tritium-labeled ivermectin in rainbow trout following oral administration

The residue depletion and metabolism of tritium-labeled ivermectin were studied in the muscle tissue of rainbow trout following oral treatment. Fish were administered 3H-ivermectin at the dose level of 0.1 mg/kg of body weight (9.25 μCi) in a gel-capsule via stomach tube. At each of the following withdrawal times 6 fish were sedated with MS-222, euthanatized, bled, scaled and fillets with adhering skin and bile collected: 1, 3, 7, 14, 28, 35 and 42 days. The muscle tissues were homogenized in dry ice and analyzed for total radioactive residues (TRR) by sample oxidation. The homogenized tissue was further extracted with acetonitrile for residue characterization by high pressure liquid chromatography (LC).Maximum TRR of 71 ng/g and 3857 ng/mL (ivermectin equivalent concentration) were detected in muscle and bile, respectively, by sample oxidation on post-dose day 3. LC analysis of the muscle extract revealed that the maximum TRR of 55 ng/g (representing ivermectin and metabolites) was also detected on post-dose day 3. By post-dose day 35, about 65% of the TRR in the muscle tissue was an unknown metabolite. Preliminary mass spectrometry results indicated that the unknown metabolite may be 3″-O-demethyl-ivermectin B1a. This metabolite could serve as a potential marker residue for ivermectin in rainbow trout, in contrast to cattle, swine and sheep where the parent ivermectin is known to be the marker residue.

Change in proximate, amino acid and fatty acid contents in muscle tissue of rainbow trout (Oncorhynchus mykiss) after cooking

SummaryChanges in proximate, amino acid and fatty acid composition of farmed, commercially important rainbow trout (Oncorhynchus mykiss) after conventional and microwave cooking were analysed. Rainbow trouts cooked in microwave ovens had statistically significant higher total protein, total fat, and ash than electrical oven‐cooked samples. The amounts of essential and nonessential amino acids were not different between cooking methods, but the difference between raw and cooked samples was significant. Lysine, leusine, methionine, threonine, valine, arginine and histidine were found most in microwave‐cooked rainbow trouts whereas isoleucine, tyrosine and phenylalanine were found most in electrical oven‐cooked samples. As total saturated fatty acid and total monounsaturated fatty acids amount were not statistically different between the cooking methods, the difference between raw and cooked fillets was found statistically significant (P &lt; 0.05). There was no statistically significant difference between raw and cooked fillets in total n‐3 and n‐6 contents.

Changes in concentrations of microcystins in rainbow trout, freshwater mussels, and cyanobacteria in Lakes Rotoiti and Rotoehu

Microcystin concentrations in cyanobacteria and their accumulation in rainbow trout (Oncorhynchus mykiss) and freshwater mussels (Hyridella menziesi) in Lakes Rotoiti and Rotoehu (New Zealand) were investigated. Hatchery rainbow trout were added to an enclosure in Lake Rotoiti where concentrations of microcystins in the phytoplankton and cyanobacterial cell concentrations could be closely monitored. Rainbow trout that were free to roam in the entire area of each lake were also included in the study. Freshwater mussels were suspended subsurface in cages in the enclosure. Phytoplankton samples, rainbow trout liver and muscle tissue, and the tissues of mussels were analyzed for microcystins using the ADDA-ELISA method, and selected samples were analyzed using LC-MS. A maximum concentration of microcystins in the phytoplankton samples of 760 microg L(-1) was recorded in Te Weta Bay, Lake Rotoiti, in March 2004. ELISA results confirmed microcystin immunoreactivity in rainbow trout liver and muscle tissues and in freshwater mussels. The microcystin congeners LR, YR, RR, AR, FR, LA, and WR were detected by LC-MS in caged freshwater mussels in Lake Rotoiti but were not detected in either muscle or liver tissue of rainbow trout. The daily tolerable intake limit of microcystins for human consumption recommended by the World Health Organisation is 0.04 microg kg(-1) day(-1). Modeling was carried out for the human intake of microcystin compounds from rainbow trout muscle tissue, and the potential health risks were estimated, assuming the ADDA-ELISA was determining compounds of toxicity equivalent to microcystin-LR.