Dataset Information

Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture.

ABSTRACT: Investigating the mechanisms that fish employ to maintain homeostasis in their everyday life requires measurements of physiological and behavioural responses in the field. With multivariate bio-loggers, we continuously measured gastrointestinal blood flow (GBF), heart rate, activity and body temperature in rainbow trout (Oncorhynchus mykiss) swimming freely amongst ~5000 conspecifics in a sea cage. Our findings clearly demonstrate that while both acute aquaculture-related stress and spontaneous activity resulted in transient reductions in GBF (i.e. reductions of up to 65%), recovery from stressful handling practices subsequently involved a substantial and prolonged gastrointestinal hyperemia far beyond the level observed prior to the stressor. The gastrointestinal hyperemia may be necessary to repair the damage to the gastrointestinal tract caused by acute stress. Furthermore, heart rate responses to acute stress or voluntary activity differed depending on the individual's physiological state. Stressed fish (i.e. mean heart rates >70 beats min^-1) exhibited a bradycardic response to acute stress or activity, whereas fish with mean heart rates <60 beats min^-1 instead demonstrated strong tachycardic responses. Remote monitoring of physiological and behavioural variables using bio-loggers can provide unique insights into 'real-life' responses of animals, which can largely differ from the responses observed in confined laboratory settings.

SUBMITTER: Brijs J

PROVIDER: S-EPMC6591390 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture.

Brijs Jeroen J Sandblom Erik E Axelsson Michael M Sundell Kristina K Sundh Henrik H Kiessling Anders A Berg Charlotte C Gräns Albin A

Scientific reports 20190624 1

Investigating the mechanisms that fish employ to maintain homeostasis in their everyday life requires measurements of physiological and behavioural responses in the field. With multivariate bio-loggers, we continuously measured gastrointestinal blood flow (GBF), heart rate, activity and body temperature in rainbow trout (Oncorhynchus mykiss) swimming freely amongst ~5000 conspecifics in a sea cage. Our findings clearly demonstrate that while both acute aquaculture-related stress and spontaneous ...[more]

PMID: 31235773

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Project description:BACKGROUND AND OBJECTIVES:Streptococcosis/lactococcosis is a hyperacute systemic disease that can occur in marine and fresh waters of many species of fish. The aim of this work was to study the disease outbreak in the major rainbow trout (Oncorhynchus mykiss) production of Iran. MATERIALS AND METHODS:108 Gram positive cocci isolates were obtained from diseased trout in seven provinces with major trout production during 2008 till 2009. These bacterial isolates were characterized using phenotypic and molecular studies. The isolates were also analysed phylogeneticaly and compared with the available data. RESULTS:49 samples (45.37%) were identified as Streptococcus iniae, 37 samples (35.2%) matched with Lactococcus garvieae; and 22 samples (19.43%) were identified as members of Streptooccus genus by culture-based and biochemical tests of API 50 CH, API 20 STREP and rapid 32 STREP systems. Using universal primers for differentiation of Streptococcus sp. and Enterococcus sp, all 108 samples were identified as Streptococcus sp. with a target region of 500 bp. Single specific PCR resulted in identification of 64 (59.2%) isolates as S. iniae and 44 (40.8%) isolates as L. garvieae. The phylogenetic analysis of the S. iniae isolates resulted in maximal similarity to some strains reported from Taiwan and to all Brazilian strains. Also, one strain showed less sequence similarity values with other tested strains although this strain has high similarity with ATCC 29178 strain, all reported Chinese, and some Taiwanian strains. Also, analysis of S. iniae LctO gene sequence showed that this isolate clustered within the S. iniae group. The sequence analysis of L. garvieae strains also showed that they have maximum similarity to all Japanese and Chinese strains, but one strain has lower sequence similarity values with all other recorded strains. CONCLUSION:[corrected] The results of this study clearly show that trout farming in Iran is severely affected by both species of S. Iniae and L. garvieae and requires serious preventive criteria.

Project description:Metabolic processes and sexual maturation closely interact during the long-distance reproductive migration of many fish species to their spawning grounds. In the present study, we have for the first time used exercise experimentally to investigate the effects on sexual maturation in rainbow trout. Pubertal autumn-spawning seawater-raised female rainbow trout Oncorhynchus mykiss (n=26; 50-cm, 1.5-kg) were rested or swum at a near optimal speed of 0.75 body-lengths per second in a 6,000 L swim-flume under natural reproductive conditions (16 Â°C fresh-water, starvation, 8h-light:16h-dark photoperiod). Fish were sampled after arrival and subsequently after 10 days (resting or swimming 307 km) and 20 days (resting or swimming 636 km). Ovarian development was significantly reduced in the swimmers. Analysis of the expression of key factors in the reproductive axis included pituitary kiss1-receptor, lh and fsh and ovarian lh-receptor, fsh-receptor, aromatase and vitellogenin-receptor (vtgr). Swimmers had lower pituitary lh and ovarian vtgr expression than resters. Furthermore, the number of late vitellogenic oocytes was lower in swimmers than in resters, probably resulting from the lower vtgr expression, and vitellogenin plasma levels were higher. Therefore, swimming exercise suppresses oocyte development possibly by inhibiting vitellogenin uptake. Transcriptomic changes that occurred in the ovary of exercised fish were investigated using a salmonid cDNA microarray platform. Protein biosynthesis and energy provision were among the sixteen functional categories that were all down-regulated in the ovary. Down-regulation of the transcriptomic response in the ovary illustrates the priority of energy reallocation and will save energy to fuel exercise. A swimming-induced ovarian developmental suppression at the start of vitellogenesis during long-term reproductive migration may be a strategy to avoid precocious muscle atrophy. In order to simulate the natural reproductive conditions of anadromous salmonids, experiments were performed with sea water-raised rainbow trout, Oncorhynchus mykiss. Resters and swimmers were starved during the experiment, seawater was replaced by fresh water and photoperiod was changed. These changes were expected to affect reproductive parameters but as âbackgroundâ effect because both resters as swimmers were experiencing these conditions at the same time in the same set-up. Any additional effects in swimming fish would thus be caused by swimming only. Pubertal autumn spawning rainbow trout (n=26; ~50 cm, ~1.5 kg) were purchased from a Danish exporter (Frederiksvaerk Aleexport) where they had been raised for 2 years in freshwater followed by 4 months in sea water cages at 10 â°. They were transferred by truck within 16 h to Spakenburg (Spakenburg Paling, The Netherlands) and subsequently in the same water in a similar holding tank to the swim-flume at Leiden University (The Netherlands). The next day, 5 randomly chosen fish were sampled as âstartâ-group while others were randomly divided into a ârestâ-group (n=10) and a âswimâ-group (n=11). During the following 4 days, the brackish 10 â° water was stepwise replaced by freshwater at 16 Â°C and photoperiod was changed from 16L:8D to 8L:16D. Fish were then acclimatized for two days to their new conditions. Subsequently, swimmers were first swum at a speed of 0.33 body-lengths per second (BL/s) which was increased the next day to the final, near optimal speed of 0.75 BL/s (0.34 m/s or 29.4 km/day). Fish were sampled after 10 days (5 resters and 5 swimmers) and 20 days (5 resters and 6 swimmers). At sampling, fish were anesthetized using oil of cloves that was commercially purchased from a drugstore (diluted 1:10 in ethanol and used at a dosage of 1.5 ml/l). Fish were euthanized by decapitation and dissected for the ovary which was flash frozen in liquid nitrogen. RNA was isolated from pituitary and ovary samples according to the TRIZOL reagent protocol by Invitrogen (Baro, Spain). Isolated RNA was DNAse treated using RQ1 DNAse Promega (Madison, USA) and reverse transcribed using Superscript IIITM (Baro, Spain) according to the manufacturerâs protocol. Microarray analyses were performed on ovarian tissue for 20-days-swimmers vs. 20-days-resters. A rainbow trout cDNA microarray platform was used that was previously validated and described by Koskinen et al., 2004ab, Krasnov et al., 2005, MacKenzie et al., 2006ab, 2008 and Djordjevic et al., 2009, and deposited in GEO under accession number GPL1212, the original cDNA microarray (SFA2.0 chip), and GPL6154; the updated 1.8 K platform. This platform compromises 1818 genes representing 366 functional categories. Total RNA was extracted from flash frozen samples from experimental fish of the 20-days-swim group (n=5) and 20-days-rest group (n=5) like described before. Total RNA corresponding to pooled samples from the swim or rest groups was labeled with Cye3 and Cye5-dCTP (GE Healthcare, Barcelona, Spain) using SuperScript III reverse transcriptase (Invitrogen, Baro, Spain) and oligo(dT) primer. In our experience, reverse labeling combined with multiple replication of spots provide robust normalization and high statistical power of analyses. cDNA was purified with MicroconYM30 (Millipore). The slides were pretreated with 1% BSA(fraction V), 20 Ã SSC, 10% SDS (30 min at 50Â°C) and washed with 2 Ã SSC (3 min) and 0.2 Ã SSC (3 min) and hybridized overnight in cocktail containing 50 Ã Denhardt's, 20 Ã SSC, 10% SDS, 10Î¼g/Î¼l polyadenylate and 10 Î¼g/Î¼l yeast tRNA. All chemicals were from Sigma-Aldrich. Scanning was performed with ScanArray 5000 and images were processed with QuantArray (GSI Luminomics). The measurements in spots were filtered by criteria I/B â¥ 3 and (I-B)/(SI + SB) â¥ 0.6, where I and B are the mean signal and background intensities and SI, SB are the standard deviations. After subtraction of mean background, LOWESS normalization was performed. To assess differential expression of genes, the normalized log intensity ratios (expression ratio) were analyzed with Student's t-test (P <0.05). Validation of the microarray was performed by Q-PCR of 6 differentially expressed genes (DEGs) as described above. The used primers were either published (Alpha-globin I-1: Donate Jimeno, 2008) or designed, again by using the Genamics software.

Project description:In recent years, poikilothermic animals such as fish have increasingly been exposed to stressful high-temperature environments due to global warming. However, systemic changes in fish under thermal stress are not fully understood yet at both the transcriptome and proteome level. Therefore, the objective of this study was to investigate the immuno-physiological responses of fish under extreme thermal stress through integrated multi-omics analysis. Trout were exposed to acute thermal stress by raising water temperature from 15 to 25 °C within 30 min. Head-kidney and plasma samples were collected and used for RNA sequencing and two-dimensional gel electrophoresis. Gene enrichment analysis was performed: differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were identified to interpret the multi-omics results and identify the relevant biological processes through pathway analysis. Thousands of DEGs and 49 DEPs were identified in fish exposed to thermal stress. Most of these genes and proteins were highly linked to DNA replication, protein processing in the endoplasmic reticulum, cell signaling and structure, glycolysis activation, complement-associated hemolysis, processing of released free hemoglobin, and thrombosis and hypertension/vasoconstriction. Notably, we found that immune disorders mediated by the complement system may trigger hemolysis in thermally stressed fish, which could have serious consequences such as ferroptosis and thrombosis. However, antagonistic activities that decrease cell-free hemoglobin, heme, and iron might be involved in alleviating the side effects of thermally induced immuno-physiological disorders. These factors may represent the major thermal resistance traits that allow fish to overcome extreme thermal stress. Our findings, based on integration of multi-omics data from transcriptomics and proteomics analyses, provide novel insight into the pathogenesis of acute thermal stress and temperature-linked epizootics.

Project description:Infectious hematopoietic necrosis virus (IHNV) and Flavobacterium psychrophilum are major pathogens of farmed rainbow trout. Improved control strategies are desired but the influence of on-farm environmental factors that lead to disease outbreaks remain poorly understood. Water reuse is an important environmental factor affecting disease. Prior studies have established a replicated outdoor-tank system capable of varying the exposure to reuse water by controlling water flow from commercial trout production raceways. The goal of this research was to evaluate the effect of constant or pulsed reuse water exposure on survival, pathogen prevalence, and pathogen load. Herein, we compared two commercial lines of rainbow trout, Clear Springs Food (CSF) and Troutex (Tx) that were either vaccinated against IHNV with a DNA vaccine or sham vaccinated. Over a 27-day experimental period in constant reuse water, all fish from both lines and treatments, died while mortality in control fish in spring water was <1%. Water reuse exposure, genetic line, vaccination, and the interaction between genetic line and water exposure affected survival (P<0.05). Compared to all other water sources, fish exposed to constant reuse water had 46- to 710-fold greater risk of death (P<0.0001). Tx fish had a 2.7-fold greater risk of death compared to CSF fish in constant reuse water (P ≤ 0.001), while risk of death did not differ in spring water (P=0.98). Sham-vaccinated fish had 2.1-fold greater risk of death compared to vaccinated fish (P=0.02). Both IHNV prevalence and load were lower in vaccinated fish compared to sham-vaccinated fish, and unexpectedly, F. psychrophilum load associated with fin/gill tissues from live-sampled fish was lower in vaccinated fish compared to sham-vaccinated fish. As a result, up to forty-five percent of unvaccinated fish were naturally co-infected with F. psychrophilum and IHNV and the coinfected fish exhibited the highest IHNV loads. Under laboratory challenge conditions, co-infection with F. psychrophilum and IHNV overwhelmed IHNV vaccine-induced protection. In summary, we demonstrate that exposure to reuse water or multi-pathogen challenge can initiate complex disease dynamics that can overwhelm both vaccination and host genetic resistance.

Dataset Information

Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture.

Publications

Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture.

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