Fish Liver Research Articles

The effects of Pediococcus acidilactici MA18/5M on growth performance, gut integrity, and immune response using in vitro and in vivo Pacific salmonid models.

Microbial management is central to aquaculture's efficiency. Pediococcus acidilactici MA18/5M has shown promising results promoting growth, modulation of the immune response, and disease resistance in many fishes. However, the mechanisms through which this strain confers health benefits in fish are poorly understood, particularly in Pacific salmonid models. Briefly, the aims of this study were to i) assess the protective effects of P. acidilactici MA18/5M by examining gut barrier function and the expression of tight junction (TJ) and immune genes in vitro and in vivo, and ii) to determine the protective effects of this strain against a common saltwater pathogen, Vibrio anguillarum J382. An in vitro model of the salmonid gut was employed utilizing the cell line RTgutGC. Barrier formation and integrity assessed by TEER measurements in RTgutGC, showed a significant decrease in resistance in cells exposed only to V. anguillarum J382 for 24 h, but pre-treatment with P. acidilactici MA18/5M for 48 h mitigated these effects. While P. acidilactici MA18/5M did not significantly upregulate tight junction and immune molecules, pre-treatment with this strain protected against pathogen-induced insults to the gut barrier. In particular, the expression of ocldn was significantly induced by V. anguillarum J382, suggesting that this molecule might play a role in the host response against this pathogen. To corroborate these observations in live fish, the effects of P. acidilactici MA18/5M was evaluated in Chinook salmon reared in real aquaculture conditions. Supplementation with P. acidilactici MA18/5M had no effect on Chinook salmon growth parameters after 10 weeks. Interestingly, histopathological results did not show alterations associated with P. acidilactici MA18/5M supplementation, indicating that this strain is safe to be used in the industry. Finally, the expression pattern of transcripts encoding TJ and immune genes in all the treatments suggest that variation in expression is more likely to be due to developmental processes rather than P. acidilactici MA18/5M supplementation. Overall, our results showed that P. acidilactici MA18/5M is a safe strain for use in fish production, however, to assess the effects on growth and immune response previously observed in other salmonid species, an assessment in adult fish is needed.

A multi-scale tracking approach for conserving large migratory fish in an open coastal environment

Coastal habitats serve essential roles in the life cycles of migratory fishes, impacting both local and regional population stability. Conservation efforts for coastal fish often rely on spatial approaches within designated boundaries to mitigate threats and enhance production. However, in open coastal environments, migratory behaviours can extend beyond these protected areas, exposing individuals to potential threats or population bottlenecks elsewhere in their range. To improve conservation outcomes, a comprehensive understanding of movements across the entire migratory range is essential. Aquatic telemetry is a valuable tool for studying these behaviours, but must be adapted to address questions at multiple spatial and temporal scales. In this study we demonstrate how a combination of telemetry techniques can capture both local and regional fish behaviours. We begin by introducing the implications of migratory behaviours for fish conservation in open coastal environments, using the Wadden Sea as an example where additional research and management are needed to address fish declines. We then present a case study which uses the Dutch Wadden Sea to illustrate how a multi-scale telemetry approach can enhance both fundamental knowledge and conservation strategies for migratory fish. Within this case study, we present the general movement strategies exhibited by coastal migrants, alongside an overview of telemetry techniques applicable for open coastal systems. We then apply a size-based assessment using a reference tag to estimate the suitability of common Wadden Sea species for long-term tracking. Drawing from these results, we select four example species to showcase how species-specific understanding of fish life history and abundance can guide tracking studies, accompanied by illustrative examples using telemetry data. Expanding from this case study, we transition to a broader discussion were we provide overarching perspectives on tracking in open coastal ecosystems and offer recommendations to enhance future tracking studies in the Wadden Sea. The integration of telemetry methodologies aligns research and management with fish movement over multiple scales, improving our understanding of fish behaviors and contributing to more effective conservation strategies.

Sistem Monitoring Kualitas Air dan Pakan Otomatis Pada Akuarium Ikan Mas Koki Terintegrasi IoT

Water is a living medium for goldfish, which greatly influences their lives. Water quality as a living medium for fish greatly influences the growth and development of goldfish; therefore, water quality must meet the needs of goldfish. Several water quality parameters that greatly influence fish life are temperature, degree of acidity (pH), and solid substances dissolved in water (TDS). The aim of this research is to design a monitoring system capable of measuring temperature, degree of acidity (pH), and solid substances dissolved in water based on the Internet of Things. This tool is used for an Internet of Things-based water quality monitoring system in goldfish aquariums, where the results obtained will be sent via smartphone to the Blynk application. And it can also provide food automatically and provide notifications if the water becomes cloudy. This tool is designed using an Arduino Uno, a Wemos D1 R2 controller, and sensors used to measure each parameter, namely the DS18B20 sensor, pH sensor, and TDS sensor. Then the feeder uses a servo to open the feed and an RTC as a timer. The results of this research conclude that the calibration results for the DS18B20 sensor have an average accuracy rate of 99% with a sensor error percentage of 1%, the pH sensor has an accuracy rate of 98.7% with an error percentage of 1.3%, and the TDS sensor has an accuracy rate of 94.59% with an error percentage of 5.41%.

Spatiotemporal variability and drivers of water microchemistry in the upper Nu-Salween river: With implications for fish habitat conservation

Microchemical maps, also known as “chemoscapes”, hold immense potential for reconstructing fish habitat utilization and guiding conservation efforts. This approach relies on matching the microchemical composition of fish calcified structures (e.g., otoliths) with the surrounding water's microchemistry. However, applying this method faces a major challenge: a clear understanding of the spatiotemporal variability and drivers of water microchemistry, particularly in vast, free-flowing river ecosystems like the Nu-Salween River, Southeast Asia's longest free-flowing river. We analyzed the spatiotemporal variability and influencing factors of water microchemistry (i.e., Na:Ca, Mg:Ca, Mn:Ca, Cu:Ca, Zn:Ca, Se:Ca, Sr:Ca, and Ba:Ca) in the upper Nu-Salween River, based on a two-year sampling. Five elemental ratios (excluding Na:Ca, Mg:Ca, and Zn:Ca) in water demonstrated significant spatiotemporal variability, with Cu:Ca having the largest spatial variation, and Mn:Ca and Sr:Ca showing the greatest temporal variation. More specifically, four elemental ratios (Cu:Ca, Se:Ca, Sr:Ca, and Ba:Ca), exhibited significant variations along the longitudinal gradient, and Mn:Ca, Cu:Ca, Sr:Ca, and Ba:Ca, showed significant differences between mainstreams and tributaries. Temporally, Mn:Ca, Cu:Ca, and Ba:Ca displayed higher values and variations during the wet season, opposing the seasonal patterns of Na:Ca, Mg:Ca, and Sr:Ca. The four-element (Ba:Ca, Sr:Ca, Mg:Ca, and Mn:Ca) forest model showed the highest classification accuracy of 93%. Linear mixed-effects models showed that spatial factors have the largest influence on the variances in water microchemistry (56.36 ± 28.64%). Our study highlights the feasibility and reliability of utilizing microchemistry to reconstruct fish habitat utilization, thereby unveiling promising avenues for a more accurate understanding of fish life history in large rivers characterized by high heterogeneity in water microchemistry. By proportionally accounting for contribution of different factors to water microchemistry variability and relating them to microchemical composition of fish calcified structures, key fish habitats (e.g., spawning grounds) and migratory routes can be more precisely identified and thus protected.

High biocompatible FITC-conjugated silica nanoparticles for cell labeling in both in vitro and in vivo models

Fluorescence nanosilica-based cell tracker has been explored and applied in cell biological research. However, the aggregation of these nanoparticles at physiological pH is still the main limitation. In this research, we introduced a novel fluorescence nano-based cell tracker suitable for application in live cells. The silica-coated fluorescein isothiocyanate isomer (FITC-SiO2) nanoparticles (NPs) were modified with carboxymethylsilanetriol disodium salt (FITC-SiO2-COOH), integrating the dianion form of FITC molecules. This nanosystem exhibited superior dispersion in aqueous solutions and effectively mitigated dye leakage. These labeled NPs displayed notable biocompatibility and minimal cytotoxicity in both in vitro and in vivo conditions. Significantly, the NPs did not have negative implications on cell migration or angiogenesis. They successfully penetrated primary fibroblasts, human umbilical vein endothelial cells and HeLa cells in both 2D and 3D cultures, with the fluorescence signal enduring for over 72 h. Furthermore, the NP signals were consistently observed in the developing gastrointestinal tract of live medaka fish larvae for extended periods during phases of subdued digestive activity, without manifesting any apparent acute toxicity. These results underscore the promising utility of FITC-SiO2-COOH NPs as advanced live cell trackers in biological research.

Possible beneficial effects of nano chitosan against doxycycline toxicity in Nile tilapia (Oreochromis niloticus)

In aquaculture, improper and illogical antibiotic use could yield negative outcomes. Therefore, this study investigates the ameliorative effects of chitosan (CS) and chitosan nanoparticles (CSNPs) against the toxicity of the antibiotic doxycycline in Nile tilapia fish. The fish were divided into four distinct categories: the first group served as the control, the second group was subjected to doxycycline (40 mg/L), the third group experienced doxycycline (40 mg/L) and CS (0.5% in fish diet), and the fourth group was exposed to doxycycline (40 mg/L) with CSNPs (0.5% in fish diet) for 15 days. Levels of creatinine, uric acid, and aspartate aminotransferase activities notably elevated (p < 0.05) in the doxycycline-treated group when compared with the control group. Meanwhile, fish in the doxycycline-exposed group demonstrated significantly lower (p < 0.05) levels of red blood cells, hemoglobin, packed cell volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and neutrophils. Conversely, mean corpuscular volume, platelets, white blood cells, and lymphocytes exhibited notably higher (p < 0.05) levels in the doxycycline group. Other hematological indicators, including monocytes and eosinophils, showed no notable variances (p > 0.05) among the studied groups. Fish treated with doxycycline exhibited notably higher (p < 0.05) interleukin-1β and interleukin-6 activity in comparison to the control group. Additionally, histopathological changes were detected in the gills, liver, and kidney tissues of doxycycline-exposed fish when contrasted with the control group. Co-exposure of CS and CSNPs significantly restored most hematological, biochemical, and immunological parameters, as well as histopathological indices, in the fish, aligning these values closer to those observed in the control group in comparison to the fish treated solely with doxycycline. In conclusion, both CS and CSNPs played an important role in moderating the negative effects of doxycycline on fish, through improving hematological indices, reductions in creatinine, uric acid, and aspartate aminotransferase activity, as well as anti-inflammatory action through reductions in interleukin-1β and interleukin-6 activity.

A novel, low-cost, and efficient separation strategy based on S-doped C3N4 for the analysis of PCDD/Fs and dioxin-like PCBs

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) are widespread and highly toxic persistent organic pollutants with similar chemical structure. The popular process for the separation of PCDD/Fs and dl-PCBs in one sample often relies on imported and expensive activated carbon, giving rise to an urgent need of inexpensive and efficient separation method. Herein, a novel, simple, and low-cost separation strategy based on sulfur-doped carbon nitride (S-C3N4) is reported. The S-C3N4 material was synthesized through simple thermal annealing with precursor of thiocyanuric acid. After recovery experiments, the optimal addition ratio of S-C3N4 was determined to be 40% mixed with silica gel. The recoveries for PCDD/Fs and dl-PCBs congeners are 32% - 105% and 60% - 70% respectively, which not only meets USEPA and Chinese standards but also shows comparable performance to activated carbon. Moreover, the proposed S-C3N4 strategy exhibits excellent performance for the analysis of PCDD/Fs and dl-PCBs in real complex samples (sediment and fish liver) in terms of detected concentrations and toxic equivalents. Overall, this study puts forward a new and low-cost avenue for the separation of PCDD/Fs and dl-PCBs, which is of remarkable meaning for motivating the development of detection techniques and domestic equipment for dioxins and other pollutants in the environment.

Acute hypoxia and reoxygenation alters glucose and lipid metabolic patterns in Hulong hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Dissolved oxygen (DO) is crucial for fish's biological functions, affecting metabolism, growth, and survival. Intensive aquaculture and live fish transportation, prevalent in the growing live fish market, often expose Hulong hybrid groupers (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) to acute hypoxic stress. This study explores the impact of acute hypoxia and subsequent reoxygenation on these groupers, focusing on their metabolic response and the underlying mechanisms in different tissues. By inducing acute hypoxic stress until mobility loss and then allowing recovery to normal DO levels, we comprehensively assessed glycolipid metabolism using RNA-seq to map regulatory networks in stress and recovery phases. This revealed significant transcriptional regulation related to hypoxic stress and glycolipid metabolism, with pathways like Insulin, HIF-1, FoxO, and cAMP playing key roles. Gill and brain tissues showed rapid changes, with significant upregulation in genes like irs, pi3k, hif-1α, and hk, whereas the liver had a more subdued response, upregulating genes linked to glycolipid metabolism like gdpd5 and amy1. During reoxygenation, lipid metabolism genes were downregulated in gills and brain, while the liver showed enhanced lipid oxidation, upregulating genes like apoa1 and fabp3, suggesting a metabolic shift from anaerobic to aerobic processes. These findings illuminate the molecular mechanisms of grouper adaptation to DO fluctuations, offering insights to mitigate acute hypoxia damage in aquaculture.

Acanthopanax senticosus cultures fermented by Lactobacillus rhamnosus enhanced immune response through improvement of antioxidant activity and inflammation in crucian carp (Carassius auratus)

Lactic acid bacteria (LAB) have been recognized as safe microorganism that improve micro-flora disturbances and enhance immune response. A well-know traditional herbal medicine, Acanthopanax senticosus (As) was extensively utilized in aquaculture to improve growth performance and disease resistance. Particularly, the septicemia, skin wound and gastroenteritis caused by Aeromonas hydrophila threaten the health of aquatic animals and human. However, the effects of probiotic fermented with A. senticosus product on the immune regulation and pathogen prevention in fish remain unclear. Here, the aim of the present study was to elucidate whether the A. senticosus fermentation by Lactobacillus rhamnosus improve immune barrier function. The crucian carp were fed with basal diet supplemented with L. rhamnosus fermented A. senticosus cultures at 2 %, 4 %, 6 % and 8 % bacterial inoculum for 8 weeks. After trials, the weight gain rate (WGR), specific growth rate (SGR) were significantly increased, especially in LGG-6 group. The results confirmed that the level of the CAT, GSH-PX, SOD, lysozyme, and MDA was enhanced in fish received with probiotic fermented product. Moreover, the L. rhamnosus fermented A. senticosus cultures could trigger innate and adaptive immunity, including the up-regulation of the C3, C4, and IgM concentration. The results of qRT-PCR revealed that stronger mRNA transcription of IL-1β, IL-10, IFN-γ, TNF-α, and MyD88 genes in the liver, spleen, kidney, intestine and gills tissues of fish treated with probiotic fermented with A. senticosus product. After infected with A. hydrophila, the survival rate of the LGG-2 (40 %), LGG-4 (50 %), LGG-6 (60 %), LGG-8 (50 %) groups was higher than the control group. Meanwhile, the pathological damage of the liver, spleen, head-kidney, and intestine tissues of probiotic fermentation-fed fish could be alleviated after pathogen infection. Therefore, the present work indicated that L. rhamnosus fermented A. senticosus could be regard as a potential intestine-target therapy strategy to protecting fish from pathogenic bacteria infection.

Structural modeling and gene expression analysis of phosvitinless vitellogenin (vgc) in the Indian freshwater murrel, Channa punctatus (Bloch, 1793)

Vitellogenin (Vg) is a female-specific egg-yolk precursor protein, synthesized in the liver of fish in response to estrogens. In the present study, complete gene of phosvitinless vitellogenin (vgc) was sequenced, its 3D structure was predicted and validated by web-based softwares. The complete nucleotide sequence of vgc was 4126 bp which encodes for 1272 amino acids and showed the presence of three conserved domains viz. LPD_N, DUF1943 and DUF1944. The retrieved amino acid sequence of VgC protein was subjected to in silico analysis for understanding the structural and functional properties of protein. mRNA levels of multiple vg genes have also been quantified during annual reproductive cycle employing qPCR. A correlation has been observed between seasonal changes in gonadosomatic index with estradiol levels and hepatic expression of three types of vg genes (vga, vgb, vgc) during ovarian cycle of murrel. During preparatory phase, when photoperiod and temperature are low; low titre of E2 in blood induces expression of vgc gene. A rapid increase in the levels of E2 favours induction of vgb and vga genes in liver of murrel during early pre-spawning phase when photoperiod is long and temperature is high in nature. These results suggest that among three vitellogenin proteins, VgC is synthesized earlier than VgA and VgB during oogenesis.

Integration of Multi-Omics, Histological, and Biochemical Analysis Reveals the Toxic Responses of Nile Tilapia Liver to Chronic Microcystin-LR Exposure.

Microcystin-LR (MC-LR) is a cyanobacterial metabolite produced during cyanobacterial blooms and is toxic to aquatic animals, and the liver is the main targeted organ of MC-LR. To comprehensively understand the toxicity mechanism of chronic exposure to environmental levels of MC-LR on the liver of fish, juvenile Nile tilapia were exposed to 0 μg/L (control), 1 μg/L (M1), 3 μg/L (M3), 10 μg/L (M10), and 30 μg/L (M30) MC-LR for 60 days. Then, the liver hepatotoxicity induced by MC-LR exposure was systematically evaluated via histological and biochemical determinations, and the underlying mechanisms were explored through combining analysis of biochemical parameters, multi-omics (transcriptome and metabolome), and gene expression. The results exhibited that chronic MC-LR exposure caused slight liver minor structural damage and lipid accumulation in the M10 group, while resulting in serious histological damage and lipid accumulation in the M30 group, indicating obvious hepatotoxicity, which was confirmed by increased toxicity indexes (i.e., AST, ALT, and AKP). Transcriptomic and metabolomic analysis revealed that chronic MC-LR exposure induced extensive changes in gene expression and metabolites in six typical pathways, including oxidative stress, apoptosis, autophagy, amino acid metabolism, primary bile acid biosynthesis, and lipid metabolism. Taken together, chronic MC-LR exposure induced oxidative stress, apoptosis, and autophagy, inhibited primary bile acid biosynthesis, and caused fatty deposition in the liver of Nile tilapia.

Feasibility of replacing fish oil with sunflower oil on the growth, body composition, fatty acid profile, antioxidant activity, stress response, and blood biomarkers of Labeo rohita.

A 90-day study was conducted to investigate the effects of substituting sunflower oil (SFO) for fish oil (FO) on various parameters in Labeo rohita (initial weight 18.21 ± 0.22 g). Five experimental diets with different levels of SFO (up to 7%) substitution for FO (0%, 25%, 50%, 75%, and 100%) were formulated, ensuring equal levels of nitrogen and lipids. The results indicated that even with 100% substitution of SFO with FO, there were no significant differences (P>0.05) were observed in growth performance. The survival rate (SR), hepato-somatic index (HSI), and viscero-somatic index (VSI) as well as whole-body composition were also nonsignificant by SFO substitution. However, the fatty acid profiles in both muscle and liver were influenced (P<0.05) by dietary substitution. Saturated fats (SFA) decreased, while monounsaturated fats (MUFA), and linoleic acid (LA) increased (P<0.05). On the other hand, the contribution of linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) decreased (P<0.05) as the amount of SFO in the diet increased. Hematology parameters, including red blood cells (RBCs), hemoglobin (Hb), and hematocrit (Hct), were not affected. Globulin (GLO) levels decreased significantly (P<0.05), while alanine transaminase (ALT) and aspartate transaminase (AST) activity showed nonsignificant increases (P>0.05). Total protein (TP) increased (P<0.05) at 100% SFO inclusion in the diet, and albumin (ALB) levels increased (P<0.05) at 75% and 100% SFO inclusion in the diet. Cholesterol (CHOL), triacylglycerol (TG), and high-density lipids (HDL) were not significantly affected (P>0.05), while low-density lipids (LDL) were significantly increased (P<0.05) compared to the control group. Cortisol (CORT) and glucose (GLU) levels showed nonsignificant (P>0.05) changes. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities in the liver and serum were not significantly (P>0.05) affected, while malondialdehyde (MDA) status was significantly (P<0.05) reduced. In conclusion, the fatty acid profile of the muscle and liver of fish was modified by the diets, and FO can be substituted with SFO up to 100% for L. rohita, which is beneficial for growth and immunity while marinating the lipid contents in fish. Our study revealed that fully replacing fish oil with SFO shows promise in fully replacing FO without compromising the growth and overall health status of the fish.

The fish–mangrove link is context dependent: Tidal regime and reef proximity determine the ecological role of tropical mangroves

AbstractTropical mangroves are known to support fish production, but natural variability in the link between mangrove habitats and fish populations undermines our ability to manage, conserve and restore this ecological relationship. This is largely due to undefined context‐dependence in the use of mangroves by fish. We collected a spatially extensive dataset of 494 mangrove fish assemblages using standardised Remote Underwater Video surveys of mangrove edge habitats from five environmentally heterogenous regions in the Indo‐Pacific. We used machine learning methods to define contextual limits of the use of mangroves by reportedly mangrove‐affiliated fish. We found that tidal range and proximity to coral reefs were the most important contextual predictors of the use of mangroves by most taxa. We established data‐driven threshold values for important contextual predictors of the use of mangroves by fish, offering new insights into the variable role played by tropical mangroves in supporting fish life histories. Where mangroves occur as part of reef seascapes in regions with limited tidal range (&lt;1.5 m), they appear to serve an important juvenile habitat function for a wide spectrum of reef fish. In regions with substantially larger tidal ranges, mangroves appear to only support certain reef species with coastal life histories. Coastal and estuary fish were able to use mangroves in a wide variety of non‐reef contexts. We demonstrate that key thresholds in environmental context can govern the functional role of mangroves, with strong implications for the role of other habitats in coastal seascapes.

Transcriptome analysis of the Nile tilapia (Oreochromis niloticus) reveals altered expression of immune genes by cadmium

Nile tilapia (Oreochromis niloticus) is a worldwide farmed fish and has been widely used for the study on comparative immunology in teleosts. It is well known that cadmium (Cd) can cause a variety of adverse effects in fish. However, data on the effects of Cd in fish liver and the defensive mechanisms of these effects using transcriptome approach are relatively scarce to date. In this study, by using an RNA sequencing approach, the gene expression profiling was performed in livers of tilapia exposed to 0 (control), 50, 100, and 200 μg/L of Cd for 2 months. The results showed that exposure to 50 μg/L Cd altered the expressions of 911 genes, while exposure to 100 and 200 μg/L Cd resulted in 4318 and 3737 differentially expressed genes compared to the control. Weighted correlation network analysis (WGCNA) and gene ontology (GO) analysis identified a 14-gene network linked to the immune system development. Further, in a fuzzy analysis, the GO term immune system development was enriched in cluster 3, and gene expression decreased with increasing Cd levels in a concentration-dependent manner. The qPCR and RNA-seq results identified 4 genes, i.e., dnmt3bb.1, sf3b1, SMARCAL1, and zap70, as convenient potential biological indicators for detecting waterborne Cd. The present results help systematically understand the effects of Cd on the hepatic transcriptome in tilapia.

Effect of tea polyphenol-trehalose complex coating solutions on physiological stress and flesh quality of marine-cultured Turbot Scophthalmus maximus during waterless transport.

The waterless transport of live fish has changed the present situation of live-fish transport. However, the waterless transport environment may cause stress in fish. This research evaluated the effect of tea polyphenol-trehalose (TPT) coating solutions on Turbot Scophthalmus maximus during waterless transport. After cold acclimation, Turbot were coated and subsequently transported in a waterless environment for 18 h. Physiological and biochemical parameters were measured, including lysozyme (LZM) and immunoglobulin M (IgM) activities, serum creatinine (Cr) and uric acid (UA) concentrations, and nutritional flavor. The results showed that the nonspecific immunity of Turbot was inhibited during the waterless transport; the LZM activity first increased and then decreased, and the serum Cr and UA concentrations significantly increased. In addition, the waterless transport promoted the breakdown of Turbot flesh proteins, leading to changes in nucleotides and free amino acids (FAAs). After waterless transport, the LZM and IgM activities in the TPT-treated Turbot were higher than those in the control group (CK), and the changes in FAA content and nucleotides were smaller than those observed in the CK group. This study shows that the use of TPT coating solution can reduce the impact of waterless transportation stress on the immune and metabolic functions of Turbot and can maintain the meat quality and flavor of Turbot.

Fractional order memcapacitive neuromorphic elements reproduce and predict neuronal function

There is an increasing need to implement neuromorphic systems that are both energetically and computationally efficient. There is also great interest in using electric elements with memory, memelements, that can implement complex neuronal functions intrinsically. A feature not widely incorporated in neuromorphic systems is history-dependent action potential time adaptation which is widely seen in real cells. Previous theoretical work shows that power-law history dependent spike time adaptation, seen in several brain areas and species, can be modeled with fractional order differential equations. Here, we show that fractional order spiking neurons can be implemented using super-capacitors. The super-capacitors have fractional order derivative and memcapacitive properties. We implemented two circuits, a leaky integrate and fire and a Hodgkin–Huxley. Both circuits show power-law spiking time adaptation and optimal coding properties. The spiking dynamics reproduced previously published computer simulations. However, the fractional order Hodgkin–Huxley circuit showed novel dynamics consistent with criticality. We compared the responses of this circuit to recordings from neurons in the weakly-electric fish that have previously been shown to perform fractional order differentiation of their sensory input. The criticality seen in the circuit was confirmed in spontaneous recordings in the live fish. Furthermore, the circuit also predicted long-lasting stimulation that was also corroborated experimentally. Our work shows that fractional order memcapacitors provide intrinsic memory dependence that could allow implementation of computationally efficient neuromorphic devices. Memcapacitors are static elements that consume less energy than the most widely studied memristors, thus allowing the realization of energetically efficient neuromorphic devices.

МИКРОБИОЛОГИЧЕСКАЯ БЕЗОПАСНОСТЬ СВЕЖЕЙ РЫБЫ, ЗАРАЖЕННОЙ ТРЕМАТОДАМИ, С УЧЕТОМ САНИТАРНОГО СОСТОЯНИЯ ВОДОЕМОВ

The purpose of research is to study the relationship between the microbiological indicators of fish infected with diplostomosis and post-diplostomosis, and the indicators of veterinary and sanitary safety of water bodies involved in its cultivation. Objectives: determination of the main parasitological indicators of infected fish (intensity of invasion (II), extensiveness of invasion (EI), species predisposition of fish to pathogens of trematodes); conducting a microbiological analysis of the obtained fresh fish and the place of its cultivation, taking into account the degree of infestation of the fish by pathogens of diplostomosis and post-diplostomosis. The study was conducted in the conditions of the North Caucasus Zonal Research Veterinary Institute in the summer and autumn seasons of the year. The study material included fish of different species: Hypophthalmichthys molitrix (silver carp), Cyprinus carpio (carp), Ctenopharyngodon idella (grass carp), Abramis brama (Bream), both infected with trematodes and clinically healthy. The water of the fish catchment site, taken from the Nizhnedonsky canal, Veselovsky, Proletarsky and Tsimlyansky re¬servoirs, was studied. The lowest AI and EI were found in fish of the species Ctenopharyngodon idella (grass carp). AI in silver carp compared to grass carp was 11.3 times higher, in carp – 9.3 times, in bream – 6.6 times; EI was 11.3 times higher in silver carp and 11.0 times higher in carp; for bream – 3.3 times. In highly invasive fish of the species Hypophthalmichthys molitrix (silver carp), Cyprinus carpio (carp), mesophilic aerobes and facultative anaerobic microorganisms were found to be 14.7 and 4.24 times more, respectively, compared to healthy fish; according to the average value of detected coliform bacteria – 2.54 and 1.86; by the number of detected Staphylococcus sp. – at 24.3 and 33.15; Escherichia sp. – at 1.5 and 0.6; Klebsiella sp. – at 110 and 85; Salmonella sp. – 45 and 0.8 times more. A correlation was established between the total microbial number of water bodies and the number of mesophilic aerobes and facultative anaerobes in caught live fish (correlation coefficient 0.99).

Do Workplace Fish Tanks Influence Employee Wellbeing and Cognitive Performance? An Embedded Mixed-Methods Study

ABSTRACT Evidence from “pet-friendly” workplaces highlights potential benefits associated with taking companion animals to work, including reduced stress among employees. Ornamental fishes carry a much lower risk than other companion animals and may be a suitable alternative in situations where other animals would introduce too great a risk (e.g., allergy, accidental injury). The aim of this study was to investigate whether watching an aquarium during the working day influenced employee wellbeing through the reduction of stress and improvements in stress-related outcomes. An embedded mixed-methods study was conducted, comprising two within-subjects trials (Trials A and B) and a qualitative follow-up. Participants were university employees and research students who participated during their working day. In Trial A (n = 30), the immediate effects of watching live fishes on mood, physiological stress, and cognitive performance were compared with the effects of watching a fish video or resting quietly. Although some outcomes improved from pre- to post-activity, there was no evidence that watching fishes (live or video) had greater effects than resting quietly. In Trial B (n = 27), the effects of repeatedly engaging in the same three activities over several weeks were examined. Watching fish videos was associated with improvements in “high pleasure-low arousal” and overall job-related affective wellbeing, but no further effects of condition were found. Qualitative follow-up data collected from a subset of participants from the experimental trials (n = 13) indicated that all three activities may be beneficial as leaving their desks provided detachment from work for a short period. Qualitative data suggested that live fishes were perceived as more engaging, but this did not translate to quantitative findings. Locating fish aquaria within offices (rather than a separate workplace location) may promote wellbeing by encouraging “microbreaks”; further research is needed to investigate this hypothesis.

Dietary intakes of vitamin D promote growth performance and disease resistance in juvenile grass carp (Ctenopharyngodon idella).

Vitamin D3 (VD3) is an essential nutrient for fish and participates in a variety of physiological activities. Notably, both insufficient and excessive supplementation of VD3 severely impede fish growth, and the requirements of VD3 for fish vary considerably in different species and growth periods. The present study aimed to evaluate the appropriate requirements of VD3 for juvenile grass carp (Ctenopharyngodon idella) according to growth performance and disease prevention capacity. In this study, diets containing six supplemental levels of VD3 (0, 300, 600, 1200, 2400, and 4800IU/kg diet) were formulated to investigate the effect(s) of VD3 on the growth performance, antioxidant enzyme activities, and antimicrobial ability in juvenile grass carp. Compared with the VD3 deficiency group (0IU/kg), the supplementation of 300-2400IU/kg VD3 significantly enhanced growth performance and increased antioxidant enzyme activities in the fish liver. Moreover, dietary supplementation of VD3 significantly improved the intestinal health by manipulating the composition of intestinal microbiota in juvenile grass carp. In agreement with this notion, the mortality of juvenile grass carp fed with dietary VD3 was much lower than that in VD3 deficient group upon infection with Aeromonas hydrophila. Meanwhile, dietary supplementation of 300-2400IU/kg VD3 reduced bacterial load in the spleen and head kidney of the infected fish, and 1200IU/kg VD3 supplementation could decrease enteritis morbidity and increase lysozyme activities in the intestine. These findings strengthened the essential role of dietary VD3 in managing fish growth and antimicrobial capacity. Additionally, based on weight gain ratio and lysozyme activities, the appropriate VD3 requirements for juvenile grass carp were estimated to be 1994.80 and 2321.80IU/kg diet, respectively.

Feasibility study for test rig assessments of fish passage conditions in a Kaplan turbine

The assessment of fish passage conditions in hydroelectric turbines consists of identifying and quantifying physical magnitudes leading to increased risks of injury of fish passing through turbines in operation. Such assessments are usually carried out either with the use of computer-based methods during design or with field testing of live fish and sensors passing through prototypes. A method in between consists of test rig experimentation, which is critical for testing fish-focused design concepts and offers the opportunity for implementing the most effective design measures for improved fish survivability. However, fish-related assessments in test rigs are not sufficiently documented for industrial applications. This work presents the main findings of an experimental campaign to quantify fish-related hydraulic magnitudes in a physical model of a Kaplan turbine in a commercial test rig. Two operating conditions were tested by releasing miniaturized autonomous sensor devices (termed Sensor Fish Mini) at the turbine intake flow, passing them through the runner in motion and recovering them at the draft tube exit. During passage, time series of acceleration, absolute pressure and rotational velocity were recorded. The recordings were then interpreted to determine the magnitude and likely location of hydraulic stressors hazardous to fish. The statistical tests on the reported measurements indicated that low pressure, collisions on the runner and rotations in the draft tube were not different between the two tested operating points. On the other hand, pressure drop and collision rates on the distributor differed considerably as a function of net head. The outcomes of this investigation showed that test rig evaluations of fish-related properties with Sensor Fish Mini can contribute to an evidence-based development of turbine geometries designed for providing safer passage conditions. Future work will investigate the scaling of test rig measurements to hydraulically equivalent magnitudes in the prototype and their biological consequences.