Towards a comprehensive understanding of the muscle proteome in Schizothorax labiatus: Insights from seasonal variations, metabolic responses, and reproductive signatures in the River Jhelum.

Proteomics is a very advanced technique used for defining correlations, compositions and activities of hundreds of proteins from organisms as well as effectively used in identifying particular proteins with varying peptide lengths and amino acid counts. In the present study, an endeavour has been put forth to create muscle proteome expression of snow trout, Schizothorax labiatus. Liquid chromatography-mass spectrometry (LC-MS) using label free quantification (LFQ) technique has extensively been carried out to explore changes in protein metabolism and its composition to discriminate across species, clarify functions and pinpoint protein biomarkers from organisms. In LFQ technique, the abundances of proteins are determined based on the signal intensities of their corresponding peptides in mass spectrometry. The main benefit of using this method is that it doesn't require pre-labelling proteins with isotopic tags, which streamlines the experimental procedure and gets rid of any bias that might have been caused by the labelling process. LFQ techniques frequently offer a wider dynamic range, making it possible to detect and quantify proteins over a broad range of abundances obtained from the complex biological materials including fish muscle. The results of proteomic analysis could provide an insight in understanding about how various proteins are expressed in response to environmental challenges. For proteomic study, two different weight groups of S. labiatus were taken from River Jhelum based on biological, physiological and logistical factors. These groups corresponded to different life stages, such as younger size and adults/brooders in order to capture potential variations in the muscle proteome related to growth and development. The proteomic analysis of S. labiatus depicted that an overall of 220 proteins in male and 228 in female fish of group 1 were noted. However, when male and female S. labiatus were examined based on spectral count and peptide abundance using ProteinLynx Global Software, a total of 10 downregulated and 32 upregulated proteins were found. In group 2 of S. labiatus, a total of 249 proteins in male and 301 in female fish were documented. When the two genders of S. labiatus were likened to one another by LFQ technique, a total of 41 downregulated and 06 upregulated proteins were identified. The variability in the protein numbers between two fish weight groups reflected biological differences, influenced by factors such as age, developmental stages, physiological condition and reproductive activities. During the study, it was observed that S. labiatus exhibited downregulated levels of proteins that were involved in feeding and growth. The contributing factors to this manifestation could be explained by lower feeding and metabolic activity of fish and decreased food availability during winter in River Jhelum. Contrarily, the fish immune response proteins were found to be significantly over-expressed in S. labiatus, indicating that the environment was more likely to undergo increased microbial infection, pollution load and anthropogenic activities. In addition, it was also discovered that there was an upregulated expression of the reproductive proteins in S. labiatus, which could be linked to the fish's pre-spawning time as the fish used in this study was collected in the winter season which is the pre-spawning period of the fish. Therefore, the present study would be useful in obtaining new insights regarding the molecular makeup of species, methods of adaptation and reactions to environmental stresses. This information contributes to our understanding of basic science and may have applications in environmental monitoring, conservation and preservation of fish species.

Characterization of gill bacterial microbiota in wild Arctic char (Salvelinus alpinus) across lakes, rivers, and bays in the Canadian Arctic ecosystems.

Teleost gill mucus has a highly diverse microbiota, which plays an essential role in the host's fitness and is greatly influenced by the environment. Arctic char (Salvelinus alpinus), a salmonid well adapted to northern conditions, faces multiple stressors in the Arctic, including water chemistry modifications, that could negatively impact the gill microbiota dynamics related to the host's health. In the context of increasing environmental disturbances, we aimed to characterize the taxonomic distribution of transcriptionally active taxa within the bacterial gill microbiota of Arctic char in the Canadian Arctic in order to identify active bacterial composition that correlates with environmental factors. For this purpose, a total of 140 adult anadromous individuals were collected from rivers, lakes, and bays belonging to five Inuit communities located in four distinct hydrologic basins in the Canadian Arctic (Nunavut and Nunavik) during spring (May) and autumn (August). Various environmental factors were collected, including latitudes, water and air temperatures, oxygen concentration, pH, dissolved organic carbon (DOC), salinity, and chlorophyll-a concentration. The taxonomic distribution of transcriptionally active taxa within the gill microbiota was quantified by 16S rRNA gene transcripts sequencing. The results showed differential bacterial activity between the different geographical locations, explained by latitude, salinity, and, to a lesser extent, air temperature. Network analysis allowed the detection of a potential dysbiosis signature (i.e., bacterial imbalance) in fish gill microbiota from Duquet Lake in the Hudson Strait and the system Five Mile Inlet connected to the Hudson Bay, both showing the lowest alpha diversity and connectivity between taxa.IMPORTANCEThis paper aims to decipher the complex relationship between Arctic char (Salvelinus alpinus) and its symbiotic microbial consortium in gills. This salmonid is widespread in the Canadian Arctic and is the main protein and polyunsaturated fatty acids source for Inuit people. The influence of environmental parameters on gill microbiota in wild populations remains poorly understood. However, assessing the Arctic char's active gill bacterial community is essential to look for potential pathogens or dysbiosis that could threaten wild populations. Here, we concluded that Arctic char gill microbiota was mainly influenced by latitude and air temperature, the latter being correlated with water temperature. In addition, a dysbiosis signature detected in gill microbiota was potentially associated with poor fish health status recorded in these disturbed environments. With those results, we hypothesized that rapid climate change and increasing anthropic activities in the Arctic might profoundly disturb Arctic char gill microbiota, affecting their survival.

Interspecies Differences in 6PPD-Quinone Toxicity Across Seven Fish Species: Metabolite Identification and Semiquantification.

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) is a recently identified contaminant that originates from the oxidation of the tire antidegradant 6PPD. 6PPD-Q is acutely toxic to select salmonids at environmentally relevant concentrations, while other fish species display tolerance to concentrations that surpass those measured in the environment. The reasons for these marked differences in sensitivity are presently unknown. The objective of this research was to explore potential toxicokinetic drivers of species sensitivity by characterizing biliary metabolites of 6PPD-Q in sensitive and tolerant fishes. For the first time, we identified an O-glucuronide metabolite of 6PPD-Q using high-resolution mass spectrometry. The semiquantified levels of this metabolite in tolerant species or life stages, including white sturgeon (Acipenser transmontanus), chinook salmon (Oncorhynchus tshawytscha), westslope cutthroat trout (Oncorhynchus clarkii lewisi), and nonfry life stages of Atlantic salmon (Salmo salar), were greater than those in sensitive species, including coho salmon (Oncorhynchus kisutch), brook trout (Salvelinus fontinalis), and rainbow trout (Oncorhynchus mykiss), suggesting that tolerant species might detoxify 6PPD-Q more effectively. Thus, we hypothesize that differences in species sensitivity are a result of differences in basal expression of biotransformation enzyme across various fish species. Moreover, the semiquantification of 6PPD-Q metabolites in bile extracted from wild-caught fish might be a useful biomarker of exposure to 6PPD-Q, thereby being valuable to environmental monitoring and risk assessment.

Divergent Temporal Trends of Mercury in Arctic Char from Paired Lakes Influenced by Climate-Related Drivers.

Climate-driven changes including rising air temperatures, enhanced permafrost degradation, and altered precipitation patterns can have profound effects on contaminants, such as mercury (Hg), in High Arctic lakes. Two physically similar lakes, East Lake and West Lake at the Cape Bounty Arctic Watershed Observatory on Melville Island, Nunavut, Canada are being affected by climate change differently. Both lakes have experienced permafrost degradation in their catchments; however, West Lake has also undergone multiple underwater Mass Movement Events (MMEs; beginning in fall 2008), leading to a sustained 50-fold increase in turbidity. This provided the unique opportunity to understand the potential impacts of permafrost degradation and other climate-related effects on Hg concentrations and body condition of landlocked Arctic char (Salvelinus alpinus), an important sentinel species across the Circum-Arctic. Our objectives were to assess temporal trends in char Hg concentrations and to determine potential mechanisms driving the trends. There was a significant decrease in Hg concentrations in East Lake char, averaging 6.5%/year and 3.8%/year for length-adjusted and age-adjusted means, respectively, from 2008 to 2019. Conversely, in West Lake there was a significant increase, averaging 7.9%/year and 8.0%/year for length-adjusted and age-adjusted mean Hg concentrations, respectively, for 2009 to 2017 (the last year with sufficient sample size). The best predictors of length-adjusted Hg concentrations in West Lake were carbon and nitrogen stable isotope ratios, indicating a shift in diet including possible dietary starvation brought on by the profound increase in lake turbidity. Our study provides an example of how increasing lake turbidity, a likely consequence of climate warming in Arctic lakes, may influence fish condition and Hg concentrations. Environ Toxicol Chem 2023;42:2712-2725. © 2023 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

The late-evolving salmon and trout join the GnRH1 club.

Although it is known that the whitefish, an ancient salmonid, expresses three distinct gonadotropin-releasing hormone (GnRH) forms in the brain, it has been thought that the later-evolving salmonids (salmon and trout) had only two types of GnRH: GnRH2 and GnRH3. We now provide evidence for the expression of GnRH1 in the gonads of Atlantic salmon by rapid amplification of cDNA ends, real-time quantitative PCR and immunohistochemistry. We examined six different salmonid genomes and found that each assembly has one gene that likely encodes a viable GnRH1 prepropeptide. In contrast to both functional GnRH2 and GnRH3 paralogs, the GnRH1 homeolog can no longer express the hormone. Furthermore, the viable salmonid GnRH1 mRNA is composed of only three exons, rather than the four exons that build the GnRH2 and GnRH3 mRNAs. Transcribed gnrh1 is broadly expressed (in 17/18 tissues examined), with relative abundance highest in the ovaries. Expression of the gnrh2 and gnrh3 mRNAs is more restricted, primarily to the brain, and not in the gonads. The GnRH1 proximal promoter presents composite binding elements that predict interactions with complexes that contain diverse cell fate and differentiation transcription factors. We provide immunological evidence for GnRH1 peptide in the nucleus of 1-year-old type A spermatogonia and cortical alveoli oocytes. GnRH1 peptide was not detected during other germ cell or reproductive stages. GnRH1 activity in the salmonid gonad may occur only during early stages of development and play a key role in a regulatory network that controls mitotic and/or meiotic processes within the germ cell.

Growth regulation in brook charr Salvelinus fontinalis.

Fish growth can be modulated through genetic selection. However, it is not known whether growth regulatory mechanisms modulated by genetic selection can provide information about phenotypic growth variations among families or populations. Following a five-generation breeding program that selected for the absence of early sexual maturity and increased growth in brook charr we aimed to understand how the genetic selection process modifies the growth regulatory pathway of brook charr at the molecular level. To achieve this, we studied the regulation of growth traits at three different levels: 1) between lines-one under selection, the other not, 2) among-families expressing differences in average growth phenotypes, which we termed family performance, and 3) among individuals within families that expressed extreme growth phenotypes, which we termed slow- and fast-growing. At age 1+, individuals from four of the highest performing and four of the lowest performing families in terms of growth were sampled in both the control and selected lines. The gene expression levels of three reference and ten target genes were analyzed by real-time PCR. Results showed that better growth performance (in terms of weight and length at age) in the selected line was associated with an upregulation in the expression of genes involved in the growth hormone (GH)/insulin growth factor-1 (IGF-1) axis, including the igf-1 receptor in pituitary; the gh-1 receptor and igf-1 in liver; and ghr and igf-1r in white muscle. When looking at gene expression within families, family performance and individual phenotypes were associated with upregulations of the leptin receptor and neuropeptid Y-genes related to appetite regulation-in the slower-growing phenotypes. However, other genes related to appetite (ghrelin, somatostatin) or involved in muscle growth (myosin heavy chain, myogenin) were not differentially expressed. This study highlights how transcriptomics may improve our understanding of the roles of different key endocrine steps that regulate physiological performance. Large variations in growth still exist in the selected line, indicating that the full genetic selection potential has not been reached.

Molecular cloning and characterization of Cu-Zn superoxide dismutase (sod1) gene in brown trout and its expression in response to acute aquaculture stressors.

Aquaculture species are often exposed to acute stressors such as low water levels and handling during routine aquaculture procedures. This might result in oxidative stress by the increased reactive oxygen species (ROS)' production (e.g., superoxide anion). The harmful effects of ROS are eliminated by a defense system, referred antioxidant defense system (ADS). sod1 is the first gene involved in the ADS. Therefore, we cloned and characterized the open reading frame of the sod1 in brown trout. Then, we determined the effects of low water level and handling stress on sod1 mRNA expression in the liver and gills at 0 min, 1 and 2 h. The total RNA isolated was used to synthesize cDNA for RT-qPCR analysis. Phylogenetic tree, identity/similarity percentages, genomic organization, and conserved gene synteny analyses were applied to characterize Sod1/sod1. While low water level stress upregulated sod1 expression in the liver compared to the control group, no significant differences were observed in the gills between experimental groups. However, brown trout differently responded to handling stress at different time intervals in both tissues. Transcriptional differences were also noted between the sexes. This study contributes to the current understanding of the molecular mechanism between oxidative stress and ADS.

Eubiotic Effect of a Dietary Bio-Aqua® and Sodium Diformate (NaDF) on Salmo trutta caspius: Innate Immune System, Biochemical Indices, Antioxidant Defense, and Expression of Immunological and Growth-Related Genes.

The present study investigated the effects of combined and singular oral administration of Bio-Aqua® with different dosages of sodium diformate (NaDF) on biochemical indices, innate immune responses, antioxidant effects, and expressions of immunological related genes of Caspian brown trout (Salmo trutta caspius). Fingerlings Salmo trutta caspius (n = 1800; initial weight 15 ± 3 g) were randomly allocated into five groups (120 fish group-1 in triplicates). Control diet: without any addition, G1, G2, G3, and G4 received diets containing 0.2 g kg-1 commercial probiotic Bio-Aqua® combined with 0, 0.5, 1.0, and 1.5% NaDF to the basal diet for 60 days according to recommended dosages reported in previous studies. Results indicated that serum bactericidal activity (G3 on day 60 and G1 on day 30) and classic complement in all groups (on day 60) (G1 and G2 on day 30) were significantly elevated (P < 0.05). The serum lysozyme, glucose, globulin, and albumin levels showed no significant differences between all groups compared to the control group (P > 0.05). On days 30 and 60 of the sampling, no significant difference was observed in the amount of superoxide disotase (SOD) and catalase (CAT) between the treatments (P > 0.05) but activity of malondialdehyde (MDA) was lower in G1 than the control (P < 0.05). The expression of the immune-regulating genes IL-10, IL-1ß, GTP, FATP, and IGF was significantly improved in all probiotic + acidifier-treated groups (P < 0.05). The current findings showed that mixture of Bio-Aqua® and NaDF (1.5% + pro) is beneficial, as it effectively improves some immune parameters and expression of immunological and growth-related genes in Caspian brown trout.

Effect of Astaxanthin on the Antioxidant Capacity and Intestinal Microbiota of Tsinling Lenok Trout (Brachymystax lenok tsinlingensis).

Astaxanthin (Ast) has been shown to be beneficial for the antioxidant capacity, immune system, and stress tolerance of fish. This study was conducted to investigate the effects of dietary supplementation of Ast on the antioxidant capacity and intestinal microbiota of tsinling lenok trout. We formulated four diets with 0 (CT), 50 (A50), 100 (A100), and 150 (A150) mg/kg Ast. The results showed that Ast increased total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px), lysozyme (LZM), and catalase (CAT) activities. Malondialdehyde (MDA) content was lower in A150 and A100 than in CT (P < 0.05). Furthermore, the activities of acid phosphatase (ACP) were higher in A100 and A150 than in CT (P < 0.05). We harvested the midgut and applied next-generation sequencing of 16S rDNA. Compared to the control group, the Ast group had a greater abundance of Halomonas. Functional analysis showed that polycyclic aromatic hydrocarbon degradation was significantly higher with Ast, while novobiocin biosynthesis and C5-branched dibasic acid metabolism were significantly lower with Ast. In conclusion, Ast could enhance the antioxidant capacity, non-specific immunity, and intestinal health of tsinling lenok trout.

Establishing brown trout primary hepatocyte spheroids as a new alternative experimental model-Testing the effects of 5α-dihydrotestosterone on lipid pathways.

Three-dimensional (3D) fish liver cultures mimic the in vivo cellular microenvironment, which is ideal for ecotoxicological research. Despite that, the application of these cultures to evaluate toxic effects in fish is scarce. A 3D model of brown trout (Salmo trutta f. fario) primary hepatocyte spheroids was optimized in this study by using DMEM/F-12 with 15 mM of HEPES, 10 mL/L of an antibiotic and antimycotic solution and FBS 10% (v/v), at 18 °C with ∼100 rpm. The selection of optimal conditions was based on a multiparametric characterization of the spheroids, including biometry, viability, microanatomy and immunohistochemistry. Biometric and morphologic stabilization of spheroids was reached within 12-16 days of culture. To our knowledge, this study is the first to culture and characterize viable spheroids from brown trout primary hepatocytes for over 30 days. Further, the 3D model was tested to explore the androgenic influences on lipidic target genes after 96 h exposures to control, solvent control, 10 and 100 µM of 5α-dihydrotestosterone (DHT), a non-aromatizable androgen. Spheroids exposed to 100 µM of DHT had decreased sphericity. DHT at 100 µM also significantly down-regulated Acox1-3I, PPARγ and fatty acid synthesis targets (i.e., ACC), and significantly up-regulated Fabp1. Acsl1 was significantly up-regulated after exposure to both 10 and 100 µM of DHT. The results support that DHT modulates distinct lipidic pathways in brown trout and show that this 3D model is a new valuable tool for physiological and toxicological mechanistic studies.

Evaluation of Proteomic and Lipidomic Changes in Aeromonas-Infected Trout Kidney Tissue with the Use of FT-IR Spectroscopy and MALDI Mass Spectrometry Imaging.

Aeromonas species are opportunistic bacteria causing a vast spectrum of human diseases, including skin and soft tissue infections, meningitis, endocarditis, peritonitis, gastroenteritis, and finally hemorrhagic septicemia. The aim of our research was to indicate the molecular alterations in proteins and lipids profiles resulting from Aeromonas sobria and A. salmonicida subsp. salmonicida infection in trout kidney tissue samples. We successfully applied FT-IR (Fourier transform infrared) spectroscopy and MALDI-MSI (matrix-assisted laser desorption/ionization mass spectrometry imaging) to monitor changes in the structure and compositions of lipids, secondary conformation of proteins, and provide useful information concerning disease progression. Our findings indicate that the following spectral bands' absorbance ratios (spectral biomarkers) can be used to discriminate healthy tissue from pathologically altered tissue, for example, lipids (CH2/CH3), amide I/amide II, amide I/CH2 and amide I/CH3. Spectral data obtained from 10 single measurements of each specimen indicate numerous abnormalities concerning proteins, lipids, and phospholipids induced by Aeromonas infection, suggesting significant disruption of the cell membranes. Moreover, the increase in the content of lysolipids such as lysophosphosphatidylcholine was observed. The results of this study suggest the application of both methods MALDI-MSI and FT-IR as accurate methods for profiling biomolecules and identifying biochemical changes in kidney tissue during the progression of Aeromonas infection.

Alteration of eggs biochemical composition and progeny survival by maternal high carbohydrate nutrition in a teleost fish.

Reproductive performances, and the factors affecting them, are of major importance especially for farmed fish in the context of the development of a sustainable aquaculture. Dietary maternal lipids have been identified as a major factor affecting reproductive performances. Nevertheless, the consequences of carbohydrates have been little studied while plant-derived carbohydrates could be increasingly used in broodstock diets. To explore this issue, 2-year-old female trout were fed either a control diet that contains no carbohydrate and a high protein content (65.7%) or a diet formulated with plant-derived carbohydrates containing 32.5% carbohydrate and 42.9% protein ('HC diet') for an entire reproductive cycle. The reproductive performances, the quality of the unfertilized eggs and the development of the progeny were carefully monitored. Although the one year HC nutrition had not impaired female growth nor spawns quality, such nutrition had increased the variability of eggs size within spawns (+ 34.0%). Moreover, the eggs produced had a modified fatty acid profile, including a significant reduction in EPA content (- 22.9%) and a significant increase in the AA/EPA ratio (+ 33.3%). The progeny were impacted by such alterations as their survival rates were significantly reduced. A lower plant-derived carbohydrate inclusion (20%) should be considered in aquafeed for female broodstock in trout.

Pro-oxidative activity of trout and bovine hemoglobin during digestion using a static in vitro gastrointestinal model.

The degradation of trout and bovine hemoglobin (Hb) and their pro-oxidant activities in washed cod muscle mince (WCM) were studied using simple pH-shifts to simulate gastrointestinal (GI) conditions (pH 7 â†’ 6 â†’ 3 â†’ 7), as well as full static in vitro GI digestion. Following gastric acidification to pH 6, metHb formation increased, especially for trout Hb. Subsequent acidification to pH 3 promoted Hb unfolding and partial or complete heme group-loss. During full GI digestion, polypeptide/peptide analyses revealed more extensive Hb-degradation in the gastric than duodenal phase, without any species-differences. When digesting WCM +/-Hb, both Hbs strongly promoted malondialdehyde (MDA), 4-hydroxy-2-hexenal (HHE), and 4-hydroxy-2-nonenal (HNE) formation, peaking at the end of the gastric phase. Trout-Hb stimulated MDA and HHE more than bovine Hb in the first gastric phase. Altogether, partially degraded Hb, and/or free hemin -both mammal and fish-derived- stimulated oxidation of PUFA-rich lipids under GI-conditions, especially gastric ones.

The effect of temperature on growth performance and aerobic metabolic scope in Arctic charr, Salvelinus alpinus (L.).

In recent years, Arctic char populations in Iceland have declined and the objective of this experiment was to throw further light on these changes by examining the effect of temperature (5, 9, 13, 17, and 21 °C) on the survival, growth rate, metabolism, and physiological indices of juvenile Arctic charr (initial mean body mass 4.02 ± 0.8 g). Mortality was 60% at 21 °C while at lower temperatures it was below 5%. However, Arctic charr populations in Iceland are declining in locations where the ambient temperature is lower, suggesting that other factors may be more important in determining the abundance of the species. The optimum temperature for growth was near 14 °C. The growth rate was progressively reduced at supra-optimum temperatures with almost no growth at 21 °C. Indicators of energy reserves: condition factor, relative intestinal mass, and hepatosomatic index are all consistent with reduced feed intake at supra-optimum temperatures. The standard and maximum metabolic rate (SMR; MMR), as well as the aerobic scope for activity (AS), were maximum at 13 °C. The routine metabolic rate (RMR) increased exponentially with temperature and, at T21, it was equal to the MMR suggesting, that the RMR was limited by the MMR. Moreover, increased heart- and gill mass at 21 °C are consistent with increased stress on the cardiovascular system. These findings are in keeping with the OCLTT hypothesis that the thermal tolerance of fish is limited by the capacity of the cardiovascular system to deliver oxygen and support metabolism. Taken together, the results of this experiment suggest, that growth rate is reduced at supra-optimum temperatures because of reduced energy intake, increased metabolic demand, and limitations in the capacity of the cardiovascular system to support metabolic rate at high temperatures. At lower temperatures, growth does not appear to be limited by the AS.

Vitellogenin Induction in Mucus from Brook Trout (Salvelinus fontinalis).

Induction of vitellogenin (VTG) is widely used as a biomarker of exposure of male or immature fish to chemicals that are agonists of the estrogen receptor (i.e., xenoestrogens). Analysis of VTG in samples of epidermal mucosa collected from fish is a non-invasive method for evaluating whether wild fish are exposed to xenoestrogens. In this study, the mean levels of VTG in the mucus of immature brook trout (Salvelinus fontinalis) collected from the Credit River in Ontario, Canada downstream of aging residential septic systems and in an agricultural watershed were 0.67 ng per mg protein, which was significantly elevated relative to the mean VTG levels of 0.22 ng per mg protein in the mucus of immature brook trout collected from a less impacted site. To validate the mucus assay, immature brook trout were exposed in the laboratory to 17α-ethinylestradiol (EE2) at nominal concentrations of 10, 50 and 100 ng/L and VTG levels in mucus from these fish showed a concentration-dependent increase relative to fish from the control treatment. This study illustrates the utility of this non-lethal method for assessing whether wild fish have been exposed in situ to xenoestrogens. Exposures to xenoestrogens from non-point sources may be impacting brook trout populations in urban watersheds in southern Ontario.

Proteomic analysis of the lake trout (Salvelinus namaycush) heart and blood: The beginning of a comprehensive lake trout protein database.

Lake trout (Salvelinus namaycush) are a top-predator species in the Laurentian Great Lakes that are often used as bioindicators of chemical stressors in the ecosystem. Although many studies are done using these fish to determine concentrations of stressors like legacy persistent, bioaccumulative and toxic chemicals, there are currently no proteomic studies on the biological effects these stressors have on the ecosystem. This lack of proteomic studies on Great Lakes lake trout is because there is currently no complete, comprehensive protein database for this species. Here, we employed proteomics approaches to develop a lake trout protein database that could aid in future research on this fish, in particular exposomics and adductomics. The current study utilized heart tissue and blood from two lake trout. Our previous work using lake trout liver revealed 4194 potential protein hits in the NCBI databases and 3811 potential protein hits in the UniProtKB databases. In the current study, using the NCBI databases we identified 838 proteins for the heart and 580 proteins for the blood tissues in the biological replicate 1 (BR1) and 1180 potential protein hits for the heart and 561 potential protein hits for the blood in BR2. Similar results were obtained using the UniProtKB databases. This study builds on our previous work by continuing to build the first comprehensive lake trout protein database and provides insight into protein homology through evolutionary relationships. This data is available via the PRIDE partner repository with the dataset identifier PXD023970.

Health benefits and risks associated with element uptake from grilled fish and fish products.

BACKGROUND: The content of essential and toxic elements in grilled fish (Atlantic salmon, trout) and in 20 assortments of fish products was examined. The aim of this study was to assess the fulfilment of the demand for Zn, Fe, Mn and Cu based on recommended dietary allowances (RDAs) or adequate intakes (AIs) and to assess the health risk associated with the consumption of Al, Pb and Cd. The risk assessment was based on estimated weekly intake (EWI), hazard index (HI), target risk ratio (THQ) and percentage: provisional tolerable weekly intake (PTWI) for Al, tolerable weekly intake (TWI) for Cd and reference dose lower bound (BMDL) for Pb. RESULTS: Taking into account the health benefits, the best source of Fe, Cu and Mn was found to be fish products in cans and jars, 150 g of which covered the daily requirement: Fe 9.39%, Cu 2.91% and Mn 1.21%. Smoked fish covered the RDA for Zn to 5.69%. Moreover, the uptake of toxic elements was as follows: Al 0.45% PTWI: Pb 0.74% BMDL10 and Cd 2.20% TWI. The THQ values for Pb and Cd were significantly lower than 1, whereas for Al it reached as high as 4.0. CONCLUSION: The obtained results indicate that there is no risk related to the intake of Pb and Cd with the consumption of the tested fish products. Low consumption of fish by Poles, however, contributes to their small share in covering the demand for microelements, i.e. Zn, Fe, Mn and Cu. © 2021 Society of Chemical Industry.

Life through a wider scope: Brook Trout (Salvelinus fontinalis) exhibit similar aerobic scope across a broad temperature range.

Brook Trout (Salvelinus fontinalis) have been widely introduced throughout the world and are often considered as direct competitors with native salmonid species. Metabolic rate is one metric we can examine to improve our understanding of how well fish perform in different habitats, including across temperature gradients, as metabolism can be directly influenced by environmental temperatures in ectotherms. We estimated the standard metabolic rate, maximum metabolic rate, and aerobic scope of lab-reared juvenile Brook Trout (~1 year) using intermittent-flow respirometry across a range of temperatures (5-23 °C) likely experienced in the wild. We included a diurnal temperature cycle of ±1.5 °C for each treatment temperature to simulate temporal variation observed in natural waterbodies. Standard metabolic rate and maximum metabolic rate both increased with acclimation temperature before appearing to plateau around 20 °C, while mass specific aerobic scope was found to increase from a mean of 287.25 ± 13.03 mg O2·kg-1·h-1 at 5 °C to 384.85 ± 13.31 mg O2·kg-1·h-1 at 15 °C before dropping at higher temperatures. Although a slight peak was found at 15 °C, the generally flat thermal performance curve for aerobic scope suggests Brook Trout are capable of adjusting to a relatively wide range of thermal regimes, appearing to be eurythermal, or a thermal generalist, at least for salmonids. The ability of this population to maintain similar physiological performance across a wide range of temperatures may help explain why Brook Trout succeed in a variety of different thermal habitats.

Deciphering influences of testosterone and dihydrotestosterone on lipid metabolism genes using brown trout primary hepatocytes.

Despite of physiological and toxicological relevance, the potential of androgens to influence fish lipid metabolism remains poorly explored. Here, brown trout primary hepatocytes were exposed to six concentrations (1 nM to 100 µM) of dihydrotestosterone (DHT) and testosterone (T), to assess changes in the mRNA levels of genes covering diverse lipid metabolic pathways. Acsl1, essential for fatty acid activation, was up-regulated by T and DHT, whereas the lipogenic enzymes FAS and ACC were up-regulated by the highest (100 µM) concentration of T and DHT, respectively. ApoA1, the major component of high-density lipoprotein (HDL), was down-regulated by both androgens. PPARγ, linked to adipogenesis and peroxisomal ß-oxidation, was down-regulated by T and DHT, while Acox1-3I, rate-limiting in peroxisomal ß-oxidation, was down-regulated by T. Fabp1, StAR and LPL were not altered. Our findings suggest that androgens may impact on lipid transport, adipogenesis and fatty acid ß-oxidation and promote lipogenesis in fish liver.

Bisphenol A and Bisphenol S Induce Endocrine and Chromosomal Alterations in Brown Trout.

Bisphenol A is a widely used compound found in large amount of consumer products. As concerns have been raised about its toxicological and public health effect, the use of alternatives to bisphenol A are now increasing. Bisphenol S is one of the analogues being used as a replacement for bisphenol A despite the fact that little is known about the effects of bisphenol S on living organisms. In this study, we investigated the potential endocrine and genotoxic effects of bisphenol A and bisphenol S in juvenile brown trout (Salmo trutta). The fish were exposed to the compounds for either 2 weeks or 8 weeks via sustained-release cholesterol implants containing doses of 2 mg/kg fish or 20 mg/kg fish of the substances. The effects on the thyroid hormone levels and the estrogenic disrupting marker vitellogenin were evaluated, along with the genotoxic markers micronucleated cells and erythrocyte nuclear abnormalities. An increase in plasma vitellogenin was observed in fish exposed to the high dose of bisphenol A for 2 weeks. At this experimental time the level of the thyroid hormone triiodothyronine (T3) in plasma was elevated after bisphenol S exposure at the high concentration, and paralleled by an increase of micronucleated cells. Moreover, bisphenol A induced an increase of micronuclei frequency in fish erythrocytes after the exposure at the lowest dose tested. Taken together the results indicate that both bisphenol A and its alternative bisphenol S cause endocrine disrupting and genotoxic effects in brown trout, although suggesting two different mechanisms of damage underlying bisphenol A and bisphenol S activity.