Stress Response In Rainbow Trout Research Articles

Potential role of miR-8159-x in heat stress response in rainbow trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss) is a representative species of cold-water fish. Elevated temperatures during summer often result in significant high mortality rates. MicroRNAs (miRNAs) are class of small non-coding RNAs that play a crucial role as post-transcriptional regulators in various biological processes. Emerging evidence suggests that miRNAs are important regulators role during heat stress. Analyzing previously obtained miRNA-sequencing data, we observed substantial down regulation of miR-8159-x in the liver tissue of heat stressed rainbow trout. In this study, we conducted a dual luciferase reporter assay to validate that miR-8159-x target, a key gene involved in heat stress in rainbow trout. By examining the expression patterns of miR-8159-x and hsp90a1 in the liver tissue at 18°C (CG) and 24°C (HS) groups, we propose that miR-8159-x may negatively regulate hsp90a1. Furthermore, in vitro hepatocyte assay, transfection with miR-8159-x mimics significantly reduced the expression level of hsp90a1, whereas transfection with a miR-8159-x inhibitor yielded the opposite effect. Additionally, overexpression of miR-8159-x inhibited cell proliferation and induced apoptosis in normal rainbow trout hepatocytes. We further investigated the effects of miR-8159-x overexpression or inhibition on the mRNA and protein levels of the target gene hsp90a1 under heat stress conditions. In conclusion, our findings suggest that miR-8159-x participates in the biological response to heat stress by targeting hsp90a1. These results contribute to a better understanding of the molecular mechanisms underlying heat stress in rainbow trout and provide valuable insights for future research.

Effects of Dietary Medlar (Mespilus germanica L.) Extract on Growth Performance, Innate Immune Characteristics, Antioxidant Status, and Responses to Crowding Stress in Rainbow Trout (Oncorhynchus mykiss).

High stocking density is a stress factor that potentially affects physiological and immune responses. In this study, the effects of medlar (Mespilus germanica) extract (ME) supplementation on growth performance, antioxidant, immune status, and stress responses in rainbow trout (Oncorhynchus mykiss) were studied. Six hundred fish (40.19 ± 1.09 g; average fish weight ± standard error) were distributed randomly into five experimental groups (assayed in triplicates). The experimental diets were formulated as follows: 0 (T1, control), 0.5% (T2), 1% (T3), 1.5% (T4), and 2% (T4). After 60 days feeding trial, the fish were confined, and the density increased (60 kg/m3) for further 14 days. Results showed significant increases in final weight (FW), weight gain (WG), specific growth rate, and feed intake in the T4 compared to the control (P < 0.05). The feed conversion ratio (FCR) in T4 significantly decreased compared to the control (P < 0.05). Also, the treated groups showed significant improvements in catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), lysozyme (LYZ), total immunoglobulin (total Ig), respiratory burst activity (RBA), total protein, and phagocytosis (PHA) (P < 0.05). Moreover, compared with the control group, supplementation could significantly decrease glucose (GLU) and cortisol (CORT), alanine transaminase (ALT), lactate dehydrogenase (LDH), aspartate transaminase (AST), and alkaline phosphatase (ALP) (P < 0.05). After the challenge, FW and WG in all treated challenge groups were significantly improved compared to the control group (P < 0.05). FCR showed a significant decrease in all treated challenged groups compared to the control group (P < 0.05). However, malondialdehyde, CAT, GPx, SOD, LYZ, complement activity (C3 and C4), total Ig, RBA, peroxidase, and PHA in challenged treated groups were significantly increased compared to the control group (P < 0.05). All treated challenged groups showed lower ALT, LDH, AST, ALP, GLU, and CORT levels than the control group (P < 0.05). The experiment herein successfully demonstrated that dietary ME stimulated fish growth, antioxidant status, and immune responses in crowding conditions and can be recommended as beneficial feed additives for rainbow trout.

Evolution, characterization, and immune response function of long-chain acyl-CoA synthetase genes in rainbow trout (Oncorhynchus mykiss) under hypoxic stress.

Long-chain acyl-CoA synthetases (Acsls), members of the acyl-activating enzyme superfamily, haves been systematically characterized in mammals and certain fishes, but the research on their involvement in reproductive development and hypoxic stress response in rainbow trout remains limited. In this study, we investigated the acsl gene structure and physical and chemical characteristics and the evolutionary relationship among acsl genes using the NCBI/Ensembl database. Using hypoxia treatment experiment, acsl gene expression in various organs and its regulation were investigated. A total of 11 acsl genes were identified in rainbow trout. Phylogenetic analyses found that acsl genes in rainbow trout were clustered into two clades: acsl3/4 and acsl1/2/5/6, and the additional gene duplication observed resulted from the third round of genome duplication unique to teleosts. Multiple sequence alignment and conserved motif analyses showed that the sequence of acsl proteins was highly conserved. Real-time quantitative PCR (RT-qPCR) showed that the acsl genes were highly expressed in immune tissues (liver and head kidney). Under hypoxia, the expression of acsl genes was upregulated, suggesting that they enhance the tolerance to hypoxia and are involved in the immune response in rainbow trout. Our study provides valuable insights into teleost evolution and effects of hypoxia on biological immunity and form a basis for further research on the functional characteristics of acsl genes.

Skin Mucus as a Relevant Low-Invasive Biological Matrix for the Measurement of an Acute Stress Response in Rainbow Trout (Oncorhynchus mykiss)

Skin mucus is a non-lethal and low-invasive matrix appropriate to assess fish welfare as it contributes to their defence against external aggressions and reflects changes in fish health status. However, more information on the response of this matrix to specific stressors is needed. In this study, rainbow trout (Oncorhynchus mykiss) specimens were subjected to an acute stress by air exposure and sampled after 1, 6, and 24 h post-stress. Blood and skin mucus were collected, and a battery of biochemical biomarkers were measured in both matrices. Cortisol and glucose values showed the expected classical stress response in plasma, increasing after the acute stress. The same pattern was observed in skin mucus, corroborating previous data in fish, and allowing us to confirm that skin mucus can be a useful complementary matrix for stress assessment in fish. The results showed sensitivity to hypoxic stress in skin mucus for cortisol, glucose, alkaline phosphatase (ALP), aspartate transaminase (AST), alanine aminotransferase (ALT), creatinine kinase (CK), and calcium. From the 15 parameters evaluated, 12 did not show statistically significant changes between plasma and mucus; therefore, using skin mucus cannot replace the use of plasma. Finally, the principal component analysis in skin mucus revealed a complete separation between the two experimental groups, being ALP, AST, glucose, cortisol, and CK, the biomarkers that contributed the most to this separation.

The effect of Thymbra spicata hydroalcoholic extract loaded on chitosan polymeric nanoparticles on some growth performances, hematology, immunity, and response to acute stress in rainbow trout (Oncorhynchus mykiss)

This study aimed to optimize the performance of Thymbra spicata (TS) plant extract using chitosan polymeric nanoparticles (CNPs) on growth parameters, blood, immunity, and response to acute stress in rainbow trout (Oncorhynchus mykiss). TS extract-containing nanoparticles (TSCNPs) were prepared by the ion gelation method. Juvenile rainbow trout (n = 750; 30.21 ± 3.04 g) were randomly divided into 10 treatments, including an extract- nanoparticle-free control and treatments with 100, 200, 400, and 800 mg/kg diet of TS extract with and without CNPs, and one treatment with 2.5 g/kg diet of CNPs, each with three replications. After 8 weeks of experimental feeding, final weight, weight gain, feed efficiency, protein efficiency ratio, and feed conversion ratio were significantly improved in the groups fed with 200 and 400 mg/kg diet of TSCNPs compared to the other groups (P < 0.05). Carcass composition contained significantly more protein and less fat in treatments fed with TSCNPs than the other treatments (P < 0.05). Red blood cells, hemoglobin, hematocrit, white blood cells, lysozyme, ACH50, immunoglobulin, total protein, albumin, and globulin were higher in the treatment fed with 400 mg/kg diet of TSCNPs than the other groups (P < 0.05). Post-stress levels of cortisol, glucose, and lactate increased in all treatments, but the lowest levels of these parameters after 480 min of stress were observed in the treatment with 400 mg/kg diet of TSCNPs. The findings show that the use of CNPs as carriers of TS improves the performance of the plant extract in growth, blood parameters, immunity, and stress response of rainbow trout.

MiR‐434 and miR‐242 have a potential role in heat stress response in rainbow trout (Oncorhynchus mykiss)

MicroRNAs (miRNAs) are being extensively studied as they function as key metabolic regulators which play a role in the heat stress response. However, the role of miRNAs in heat stress remains uncertain and many new miRNAs have not yet been discovered. In a previous study, we performed high-throughput sequencing of differentially expressed miRNAs identified on exposing rainbow trout (Oncorhynchus mykiss) to heat stress (18 vs. 24°C), which led to the identification of two novel miRNAs, temporarily named novel miR-434 and -242. The differential expression level of these miRNAs was extremely significant (P < 0.01); we analysed target gene mRNA transcripts by bioinformatics software (miRanda). We found novel miR-434 and -242 were predicted to regulate the transcripts of heat shock 70-kDa protein 4-like (HSPA4L) and calreticulin (CRT), respectively, by bioinformatics software. Here our core objective was to validate if HSPA4L and CRT are indeed the target genes of novel miR-434 and -242, respectively, and for this purpose we used the dual-luciferase reporter assay system. Target gene sequences were synthesized and cloned into a dual-luciferase vector. To better understand the function of the target genes, we combined the previous sequencing results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. We found that novel miR-434 regulated HSPA4L expression by binding to a putative binding site in the 3'-UTR of HSPA4L, and luciferase activity inhibition was observed. In contrast, novel miR-242 was not involved in regulating CRT expression. To conclude, we believe our results should serve as a foundation for future studies aiming to comprehensively understand the mechanisms used by rainbow trout to cope with heat stress.

Effect of dietary dehydrated lemon peel (Citrus limon) supplementation on growth, hemato-immunolological and antioxidant status of rainbow trout (Oncorhynchus mykiss) under exposure to crowding stress

The effect of dietary dehydrated lemon peel (Citrus limon) powder (DLPP) on growth, hemato-immunological, antioxidant and stress responses in rainbow trout (Oncorhynchus mykiss) was investigated. Fish (26.8 ± 1.9 g) were randomly introduced to four treatments feeding diets containing 0 (control), 0.5, 1.5, and 2.5% of DLPP diets. After a 45-day period, the fish were exposed to 10-day crowding stress. At the end of feeding trial, growth performance, hematological, immunological, antioxidant parameters and cortisol levels were assessed. The results showed that the dietary DLPP had no significant effects on the fish growth performance (p > 0.05). There were no significant differences in hematological parameters between the control and DLPP before the stress, but the white blood cell significantly (p < 0.05) increased in 1.5% DLPP after stress. No differences were found in the immunological, antioxidant and cortisol before the stress (p > 0.05). After stress, the immune activity, catalase and superoxide dismutase significantly increased in 1.5% DLPP (p > 0.05). The cortisol level significantly decreased in 0.5 and 1.5% DLPP compared to the control after stress (p > 0.05). Summary, dietary 1.5% DLPP supplementation has beneficial effects to reduce crowding stress and stimulates most of the antioxidant and immune characteristics of rainbow trout, without affecting the fish growth performance.

Proteome analysis of rainbow trout (Oncorhynchus mykiss) liver responses to chronic heat stress using DIA/SWATH

Aquaculture of rainbow trout (Oncorhynchus mykiss) is severely hampered by high temperatures in summer, and understanding the regulatory mechanisms controlling responses to chronic heat stress may assist the development of measures to relieve heat stress. In the present study, biochemical parameters revealed a strong stress response in rainbow trout at 24 °C, including activation of stress defence and immune systems. Liver proteome analysis under heat stress (24 °C) and control (18 °C) conditions using DIA/SWATH identified precursors (90,827), peptides (67,028), proteins (6770) and protein groups (5124), among which 460 differentially abundant proteins (DAPs; q-value < 0.05, fold change >1.5), 201 and 259 were up- and down-regulated, respectively. Many were related to heat shock proteins (HSPs), metabolism and immunity. Gene Ontology (GO) analysis showed that some DAPs induced at high temperature were involved in regulating cell homeostasis, metabolism, adaptive stress and stimulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified metabolic pathways, protein processing in endoplasmic reticulum, PPAR signalling, and complement and coagulation cascades. Protein-protein interaction (PPI) network analysis indicated that HSP90b1 and C3 may cooperative to affect cell membrane integrity under heat stress. Our findings assist the development of strategies to relieve heat stress in rainbow trout.

Genome-wide identification of Hsp70/110 genes in rainbow trout and their regulated expression in response to heat stress.

Heat shock proteins (Hsps) play an important role in many biological processes. However, as a typical cold water fish, the systematic identification of Hsp70/110 gene family of rainbow trout (Oncorhynchus mykiss) has not been reported, and the role of Hsp70/110 gene in the evolution of rainbow trout has not been described systematically. In this study, bioinformatics methods were used to analyze the Hsp70/110 gene family of rainbow trout. A total of 16 hsp70/110 genes were identified and classified into ten subgroups. The 16 Hsp70/110 genes were all distributed on chromosomes 2, 4, 8 and 13. The molecular weight is ranged from 78.93 to 91.39 kD. Gene structure and motif composition are relatively conserved in each subgroup. According to RNA-seq analysis of rainbow trout liver and head kidney, a total of four out of 16 genes were significantly upregulated in liver under heat stress, and a total of seven out of 16 genes were significantly upregulated in head kidney. RT-qPCR was carried out on these gene, and the result were consistent with those of RNA-seq. The significantly regulated expressions of Hsp70/110 genes under heat stress indicats that Hsp70/110 genes are involved in heat stress response in rainbow trout. This systematic analysis provided valuable information about the diverse roles of Hsp70/110 in the evolution of teleost, which will contribute to the functional characterization of Hsp70/110 genes in further research.

Effects of hydroalcoholic extract of honeybee pollen on growth performance, flesh quality, and immune and stress response response of rainbow trout (Oncorhynchus mykiss)

The effects of dietary hydroalcoholic extract of honeybee pollen (HBPE) on growth performance, flesh quality, immunity and stress response were investigated. Two hundred fifty‐five rainbow trout (11.14 ± 1.06 g) were fed five diets containing increasing levels of HBPE: control, 0.25HBPE (0.25 g HBPE/kg), 0.5HBPE (0.5 g HBPE/kg), 1HBPE (1 g HBPE/kg) and 1.5HBPE (1.5 g HBPE/kg). After 56 days, rainbow trout fed the 0.5HBPE and 1HBPE diets displayed significantly higher weight gain (49.58 and 53.25 g) and protein efficiency (2.88 and 2.83) compared to those fed the control diet (4.89 and 2.05), respectively (p p p p Aeromonas hydrophila was exposed to different dosages of HBPE, a higher inhibitory zone resulted from 1,000 and 1,500 mg/ml dosage. The lower levels of plasma cortisol were observed in the 1HBPE and 1.5HBPE groups after the complement stress test. Collectively, the present findings suggest that the 1HBPE diet supported superior growth, flesh quality, immunity and stress response of rainbow trout.

Genome-Wide Identification of hsp90 Gene in Rainbow Trout (Oncorhynchus mykiss) and Their Regulated Expression in Response to Heat Stress.

In this study, we analyzed the gene structure, chemical characterizations, chromosome locations, evolutionary relationship, and expression profile of hsp90 genes with online database. In addition, the expression levels of hsp90s were also investigated under heat stress by quantitative real-time (qRT)-PCR. A total of eight hsp90 genes were identified from the rainbow trout genome. They were all distributed on chromosomes 2, 4, 8, and 13. The molecular weight ranged from 78.93 to 91.39 kDa, and the isoelectric point ranged from 4.84 to 4.96. The eight hsp90 genes were clustered into six subfamilies (A, B, C, D, E, and F). Genetic structure and conserved domain analysis revealed that all eight hsp90 genes had only one exon, and motif 1-motif 10 was shared by most genes. According to RNA-seq analysis of rainbow trout liver and head kidney, a total of seven out of eight genes were significantly upregulated under heat stress, and qRT-PCR was carried out on these seven genes; the expression levels of these genes were significantly upregulated under heat stress. The significantly regulated expressions of hsp90 genes under heat stress indicated that hsp90 genes are involved in heat stress response in rainbow trout. This study provides a theoretical basis for further study on the role of hsp90 in the heat stress tolerance of rainbow trout.

Effects of heat stress on Hsp90a2b and Hsp10 mRNA expression and blood cell apoptosis in rainbow trout Oncorhynchus mykiss (Walbaum, 1972)

To study the response to heat stress in rainbow trout Oncorhynchus mykiss (Walbaum, 1972), the expression of heat shock protein genes Hsp90a2b and Hsp10 in selected tissues and apoptosis of blood cells were investigated at water temperatures of 18, 21, 23, 24, 25 and 26°C. Expressions of Hsp90a2b in the gill, mid-kidney, brain, heart and muscle were generally upregulated with increasing temperature. Hsp90a2b expression in the liver increased rapidly at 21°C and then showed a significant decrease and finally a significant increase at 25°C and 26°C (p&lt;0.05). Hsp10 expression showed an irregular but overall increasing tendency in gill, spleen and mid-kidney and a wave-like increasing pattern in liver, heart and muscle. Levels of Hsp90a2b at 25°C and Hsp10 at 26°C in all tissues were always significantly higher compared to 18°C (p&lt;0.05). The apoptosis rate at 21°C was significantly higher than that at 18°C, followed by a fall and was the highest at 25°C. All these data indicated that the heat shock response already occurred at 21°C which induced expressions of Hsp90a2b and Hsp10 as well as blood cells apoptosis and 25°C may be a key temperature for stress response in rainbow trout.

Effects of dietary tryptophan supplementation and stocking density on growth performance and stress responses in rainbow trout (Oncorhynchus mykiss)

The aim of the present study was to investigate the effects of dietary tryptophan (Trp) supplementation on growth performance and stress responses of rainbow trout (Oncorhynchus mykiss) at low (LD) and high (HD) stocking density. For this, three diets were formulated by supplementing 0% (control), 0.5% (T0.5), and 1% (T1) Trp corresponding to 0.77, 1.85 and 3.14 g Trp per 100 g protein. In the LD treatment, the fish were initially stocked at 15 kg/m3; whereas, in the HD treatment, the fish were initially stocked at 25 kg/m3. The fish were reared under these densities and with the aforementioned diets for 70 days. After the feeding trial, the fish were sampled to determine carcass proximate composition, and blood hematological and biochemical parameters. The results showed that T0.5 had higher growth performance compared to the other treatments under the LD condition; however, there was no significant difference among the treatments under the HD condition. The increase in the fish stocking density significantly increased FCR, but the Trp-treated treatments had significantly lower FCR compared to the control treatment. Increase in the fish stocking density significantly increased carcass moisture, but decreased the carcass protein and lipid levels. The T0.5 treatment had significantly higher carcass lipid levels compared to the other treatments at the LD condition. The T0.5 treatment had significantly lower cortisol and glucose, and higher T3 levels compared to the other treatments under the LD condition; however, there was no significant difference among the treatments under the HD condition. Blood RBC and hemoglobin values significantly increased in the fish fed with 0.5% Trp supplementation; moreover, the increase in the fish stocking density significantly increased these parameters. The T0.5 treatment had significantly higher blood hematocrit levels compared to the other treatments at the LD condition. In conclusion, dietary Trp supplementation at 0.5% level is beneficial to augment growth performance in rainbow trout, when the fish initial biomass is 15 kg/m3. The mechanism of growth promotion effects of 0.5% Trp was found to be related to stress suppression. Further studies would provide data about the potential effects of Trp on rainbow trout under higher stocking densities.

Effects of lowering dietary fishmeal and crude protein levels on growth performance, body composition, muscle metabolic gene expression, and chronic stress response of rainbow trout (Oncorhynchus mykiss)

A study was conducted to evaluate the effects of lowering dietary fishmeal (FM) and crude protein (CP) levels, while maintaining essential amino acid levels, on growth performance, body composition, muscle metabolic gene expression, and chronic stress response of rainbow trout, Oncorhynchus mykiss, with and without handling stress. Eight experimental diets (isocaloric) with a 4 × 2 factorial design were formulated to contain two levels of FM (20%, 5%) and four levels of CP (48%, 45%, 42%, 39%). Diets were supplemented with increasing levels of amino acids to maintain dietary essential amino acid (EAA) levels. Trout (34.8 ± 0.3 g) were fed to apparent satiation twice daily for nine weeks to assess growth performance under laboratory rearing conditions, and then for an additional six weeks with and without exposure to handling stress (30 s of chasing followed by 30 s of netted air exposure) twice per week. The 9-week growth trial demonstrated that reducing dietary FM levels from 20% to 5% significantly reduced fish growth and increased feed conversion ratio (P < .05). Reducing dietary CP levels from 48% to 42% did not affect trout growth. A dietary FM level of 20% significantly increased whole-body dry matter, CP and total EAAs (P < .05) compared to 5% FM inclusion while increasing dietary CP level significantly decreased dry matter, crude fat, and gross energy but increased total EAAs (P < .05). Reducing FM and CP levels had no effect on measured stress indices of plasma cortisol, glucose and lysozyme activity (P > .05) after 6-weeks of repeated handling stress. The expression of genes in the gcn2/eif2α/atf4 pathway, triggered in response to protein or amino acid starvation, were evaluated. General control nonderepressible 2 (gcn2) decreased with increasing dietary CP level above 42% (P < .05), but there were no dietary effects (FM or CP levels) on eif2α (eukaryotic initiation factor 2α) or atf4 (activating transcription factor 4) expression. In total, gene expression results suggest amino acid limitations on muscle protein metabolism as a result of feeding diets below 42% CP, even when supplemented with synthetic EAA to meeting published dietary requirements. In conclusion, our study demonstrated that 5% dietary FM is insufficient for maximal growth performance, while diets balanced for EAAs show an opportunity to reduce CP level from 48% to 42% without any reduction in growth performance, body composition, metabolic amino acid sufficiency or tolerance to chronic stress. Below 42% CP, reduced growth indices suggest an imbalance in EAA availability.

Sodium Hypochlorite Provokes Stress Response in Rainbow trout: Variation in Blood Parameters as an Ecotoxicological Indicator of Freshwater Contamination

In this study we analyzed the effects of NaOCl solution on the blood and biochemical parameters of the rainbow trout Oncorhynchus mykiss (Walbaum, 1792). The treatment lasted for three days with prior dechlorination of the water. Significant differences in the concentration of K+, Ca2+, Cl-, proteins, glucose were detected and the largest variations were found for creatinine concentration (P<0.05). Significant differences were found Hct, Hb concentration, RBC, WBC, MCH and MCHC values, percentage ratio of lymphocytes, segmented granulocytes and the total number of neutrophil granulocytes (P<0.05). Small doses of NaOCl alter the acid-base balance, suggesting a very low-level adaption in the rainbow trout.

Post-exposure effects of the piscicide 3-trifluoromethyl-4-nitrophenol (TFM) on the stress response and liver metabolic capacity in rainbow trout (Oncorhynchus mykiss).

The piscicide 3-trifluoromethyl-4-nitrophenol (TFM) has been used to control invasive sea lamprey (Petromyzon marinus) populations in the Great Lakes for almost 60 years. Applied to rivers and streams containing larval lampreys, TFM seldom harms non-target fishes, but the effects of sub-lethal treatments on fish physiology are not well understood. We examined the effects of 9 h exposure to TFM on the stress axis and liver metabolic capacity of rainbow trout (Oncorhynchus mykiss) using in vivo and in vitro approaches. The fish that had been acutely exposed to TFM in vivo had increased plasma cortisol levels at 12 h post-treatment, but TFM exposure did not interfere with in vitro cortisol production in head kidney preparations. Subjecting trout to an acute handling stressor 12 h post-TFM exposure resulted in a relative attenuation of the plasma cortisol and glucose response compared to pre-stress levels. We conclude that routine TFM treatments can lead to elevations of plasma cortisol following exposure, plus a relative dampening of the stress response in rainbow trout, with high cortisol levels lasting at least 12 h post-treatment. Since the ability of the fish to produce cortisol and the liver metabolic capacity were not compromised following TFM exposure, it is likely that their ability to cope with other stressors is not altered in the long-term.

Confirmation that pulse and continuous peracetic acid administration does not disrupt the acute stress response in rainbow trout

Peracetic acid (PAA) is considered an eco-friendly alternative to other antimicrobial agents of common use in aquaculture. The literature suggests that fish can habituate to PAA exposure based on a reduction of the fish corticosteroid response to PAA administration after repeated exposures. If that is true, PAA would also be a good option from the point of view of fish physiology. However, stronger evidence is needed to confirm that the use of PAA is welfare-friendly to fish. Besides habituation, other hypothetical factors such as desensitization, physiological exhaustion or PAA-mediated endocrine disruption could potentially explain the reduction in the corticosteroid response after repeated/prolonged PAA exposure. In this study, rainbow trout that had been exposed to PAA for several weeks were challenged with a secondary chasing stressor: fish were pursued with a dipnet for 1 min and their acute response was evaluated by measuring plasma cortisol, plasma glucose, plasma lactate and brain serotonergic activity. All fish were equally able to mount a normal physiological stress response to the secondary stressor independent of previous exposure to PAA. This suggests that the decrease in the cortisol response after repeated exposure to PAA, as seen in previous studies, is a true habituation to PAA administration, which supports the use of PAA as a welfare-friendly antimicrobial agent in aquaculture.

Immune-related gene expression and physiological responses in rainbow trout (Oncorhynchus mykiss) after intraperitoneal administration of Rhodomyrtus tomentosa leaf extract: A potent phytoimmunostimulant

The immunostimulatory effects of Rhodomyrtus tomentosa leaf extract were evaluated in rainbow trout through changes in expression profile of genes involved in innate immune and antioxidant response, hematology and stress indicators. The concentrations of R. tomentosa at 10 and 100 μg per fish were administrated by intraperitoneal injection, alone or in combination with LPS. After 6 h of administration, the gene expression was measured in head kidney, spleen, and intestine. Results indicated that R. tomentosa exerted immunostimulatory effects by inducing the expression of il10, saa, hepcidin, and sod in head kidney and the expression of il10, tgfβ, and inos in intestine. In combination with LPS, the plant suppressed the expression of pro-inflammtory cytokine il1β, il8 and other consisting of saa and gpx1 in head kidney and il1β in spleen, pointing out its anti-inflammatory activities. Furthermore, the plant did not exert any impact on hematological parameters, but it was able to reduce cortisol levels when co-administered with LPS, indicating that R. tomentosa could attenuate stress response in rainbow trout. Our observations suggest that R. tomentosa induced the expression of genes involved in cytokine and innate immune response and modulated the physiological stress response as indicated by the suppressed cortisol in rainbow trout.

Effect of different dietary β -glucan dosages on regulation of stress response in rainbow trout infected by Aeromonas salmonicida

PDF HTML阅读 XML下载 导出引用 引用提醒 β-葡聚糖对杀鲑气单胞菌感染后虹鳟应激过程的调节作用 DOI: 作者: 作者单位: 1. 中国科学院海洋研究所, 山东 青岛 266071;2. 中国科学院大学, 北京 100039;3. 大连海洋大学 海洋科技与环境学院, 辽宁 大连 116023 作者简介: 纪利芹(1989-),女,博士,研究方向为鱼类营养与免疫.E-mail:goofyji@126.com 通讯作者: 中图分类号: S942 基金项目: 国家自然科学基金项目（41306152，31472312，31402283）；第56批中国博士后科学基金项目（2014M560580）；山东省博士后创新基金项目（201402005）；国家科技支撑计划项目（2014BAD08B09）；江苏省重点研发计划项目（BE2015325）；青岛市海洋经济创新发展示范城市重点项目。 Effect of different dietary β-glucan dosages on regulation of stress response in rainbow trout infected by Aeromonas salmonicida Author: Affiliation: 1. Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2. University of Chinese Academy of Sciences, Beijing 100039, China;3. School of Marine Science and Environment Engineering, Dalian Ocean University, Dalian 116023, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为研究不同浓度的）应激过程的调节作用，在虹鳟饲料中添加不同浓度的-葡聚糖（0，0.05%，0.1%，和0.2%），投喂42 d后感染杀鲑气单胞菌，在感染后第2，4和6天取样检测血清应激指标的变化，第7天时统计虹鳟的存活率。结果表明，添加-葡聚糖组的血清总蛋白（total protein，TP）浓度显著高于对照组（<0.05）。0.1%和0.2%组的血清丙二醛（malondialdehyde，MDA）活性在感染后第2天达到峰值，早于0.05%和对照组。0.1%和0.2%组血清髓过氧化物酶（myeloperoxidase，MPO）活性在感染后显著上升，而0.05%和对照组却显著下降（P<0.05）。P<0.05）。感染后第4天，<0.05）。总胆红素（total bilirubin，T-BIL）浓度在感染后显著下降（<0.05），其中0.2%组下降幅度最小。各组肝脏和脾脏热休克蛋白70基因（heat shock protein 70，HSP70）表达量在感染后都显著升高（-葡聚糖能显著提高感染杀鲑气单胞菌的虹鳟的存活率和有效减弱细菌感染引起的机体应激反应，其中0.2%剂量的保护效果最好且对应激过程的减弱效果最明显（<0.05）。 Abstract:In recent years, immunostimulants have become a new research field in aquaculture. -glucan is one of the most important immunostimulants, which can enhance the body's resistance to infection by improving the non-specific and cellular immunity of animals. The present study evaluated the effects of different dietary -glucan dosages (0, 0.05%, 0.1%, and 0.2%) on the anti-infection ability of rainbow trout () after 42 days of feeding. Thereafter, rainbow trout were infected with and sampled on the 2nd, 4th, and 6th days post-infection. Survival rates as well as the regulatory processes of serum stress-related factors were analyzed. Survival rates in the -glucan groups increased significantly compared with those in the control group after P<0.05). On the 4th day after infection, the serum total protein concentrations in all -glucan groups were significantly higher than those in the control group (<0.05). Serum malondialdehyde activity in the 0.1% and 0.2% groups reached a peak on the 2nd day post-infection, which was earlier than in the other infected groups. The activity of serum myeloperoxidase in the 0.1% and 0.2% groups increased significantly after infection, whereas in the 0.05% and control groups, it decreased significantly (-glucan groups after infection was significantly lower than that in the control group (-glucan groups increased more obviously than those in the control group (<0.05). On the 4th day after infection, the serum urea nitrogen concentration in all -glucan groups was markedly lower than that in the infected control group (<0.05). Total bilirubin (T-BIL) concentration decreased significantly after infection; however, T-BIL in the 0.2% group was clearly higher than that in the other groups. After infection, expression in the liver and spleen in all groups increased significantly. In the 0.1% and 0.2% groups, it reached a higher peak earlier than in the control group. Overall, the liver and head kidney in rainbow trout were damaged to a certain extent after infection with -glucan can effectively protect fish from damage caused by -glucan showing the best effect. 参考文献 相似文献 引证文献

Oxidative stress response of rainbow trout (Oncorhynchus mykiss) to multiple stressors

Fish can be exposed to multiple stressors at the same time, including natural toxins, environmental pollutants or feed contamination. In this study, we report on the effects of controlled exposure of rainbow trout (Oncorhynchus mykiss) to multiple stressors. In doing so, we test the hypothesis that cyanobacterial biomass and arsenic in feed combine to enhance negative effects on fish, including modulation of antioxidant response. The trout (mean weight 288 ± 59 g) were divided into six experimental groups of 25 fish each (C - control group; B - 3% lyophilised toxic cyanobacterial biomass; As5 - arsenic at 5 mg·kg–1; As50 - arsenic at 50 mg·kg–1; and two combinations of cyanobacterial biomass and arsenic (B+As5 and B+As50). All indicators of oxidative stress were determined using standard methods, showing significant changes. Overall antioxidant capacity (ferric reducing antioxidant power) decreased significantly in the liver, gills and heart after 10-days, while lipid peroxidation (thiobarbituric acid reactive substances) increased in the liver of groups exposed to cyanobacterial biomass, and in the heart of groups exposed to increased concentrations of arsenic and those under combined exposure. Levels of glutathione reductase showed a significant reduction following exposure, especially in the gills and liver. Our results indicate that the antioxidant system plays an important role in the protective response of tissues to stressors, and especially arsenic.