Apoptosis in fish: environmental factors and programmed cell death

Modulating responses of indicator genes in cellular homeostasis, immune defense and apoptotic process in the Macrophthalmus japonicus exposed to di(2-ethylhexyl) phthalate as a plastic additive

Di(2-ethylhexyl) phthalate (DEHP), have been increasingly used as plasticizers to manufacture soft and flexible materials and ubiquitously found in water and sediments in the aquatic ecosystem. The aim of the present study was to evaluate the effect of DEHP exposure on cellular homeostasis (HSF1 and seven HSPs), immune responses (ILF), and apoptotic responses (p53, BAX, Bcl-2). DEHP exposure upregulated the expression of HSF1 and ILF. Moreover, it altered the expression levels of HSPs (upregulation of HSP70, HSP90, HSP40, HSP83, and HSP67B2 and downregulation of HSP60 and HSP21) in conjunction with HSF1 and ILF in the gills and hepatopancreas of M. japonicus exposed to DEHP. At the protein level, DEHP exposure changed apoptotic signals in both tissues of M. japonicus. These findings indicate that chronic exposures to several DEHP concentrations could disturb cellular balance, damage the inflammatory and immune systems, and induce apoptotic cell death, thereby affecting the survival of M. japonicus.

Effects of ambient UVB light on Pacific oyster Crassostrea gigas mantle tissue based on multivariate data

Ambient ultraviolet radiation (UVB) from solar and artificial light presents serious environmental risks to aquatic ecosystems. The Pacific oyster, Crassostrea gigas, perceives changes in the external environment primarily through its mantle tissue, which contains many nerve fibers and tentacles. Changes within the mantles can typically illustrate the injury of ambient UVB. In this study, a comprehensive analysis of phenotypic, behavioral, and physiological changes demonstrated that extreme UVB radiation (10 W/m²) directly suppressed the behavioral activities of C. gigas. Conversely, under ambient UVB radiation (5 W/m²), various physiological processes exhibited significant alterations in C. gigas, despite the behavior remaining relatively unaffected. Using mathematical model analysis, the integrated analysis of the full-length transcriptome, proteome, and metabolome showed that ambient UVB significantly affected the metabolic processes (saccharide, lipid, and protein metabolism) and cellular biology processes (autophagy, apoptosis, oxidative stress) of the C. gigas mantle. Subsequently, using Procrustes analysis and Pearson correlation analysis, the association between multi-omics data and physiological changes, as well as their biomarkers, revealed the effect of UVB on three crucial biological processes: activation of autophagy signaling (key factors: Ca2+, LC3B, BECN1, caspase-7), response to oxidative stress (reactive oxygen species, heat shock 70, cytochrome c oxidase), and recalibration of energy metabolism (saccharide, succinic acid, translation initiation factor IF-2). These findings offer a fresh perspective on the integration of multi-data from non-model animals in ambient UVB risk assessment.

Temperature acclimation improves high temperature tolerance of rainbow trout (Oncorhynchus mykiss) by improving mitochondrial quality and inhibiting apoptosis in liver

Global warming is threatening the survival and growth of cold-water fish, and the methods to improve the high-temperature adaptability of cold-water fish need to be explored urgently. This study aims to explore the mechanism of improving high temperature tolerance of rainbow trout by temperature acclimation (TA). Rainbow trout were acclimated by two modes at 22 °C, including fluctuating TA (FA) and constant TA (CA), and thereafter subjected to heat stress (HS) at 25 °C. Results showed that TA markedly increased the critical temperature maximum (CTmax) of rainbow trout. Secondly, the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and malondialdehyde (MDA) in liver of CA + HS group significantly decreased compared to those in HS group without TA, indicating the reduction of liver injury by CA. Moreover, HS significantly induced ROS production and reduced mitochondrial membrane potential (MMP) in rainbow trout liver, but TA reduced the levels of ROS and increased the MMP in liver of rainbow trout after HS, indicating the reduced oxidative stress and mitochondrial damage. Furthermore, TA up-regulated the expression of genes related to mitochondrial autophagy, fusion, fission and biogenesis, as well as the expression of marker proteins of autophagy (LC3II) and mitophagy (Parkin) in the liver, so as to maintain mitochondrial homeostasis. Moreover, TA also inhibited the occurrence of apoptosis (decrease in bax/bcl-2), which may be owing to the reduced ROS and mitochondrial damage by TA. Interestingly, CA significantly up-regulated the genes expression of methyltransferase in the liver, which may inhibit the genes or transcription factors related to oxidative stress and apoptosis by DNA methylation. In conclusion, TA increased the upper limit of heat tolerance of rainbow trout by improving mitochondrial quality and inhibiting apoptosis in liver. This study will provide an effective solution to the risk of high temperature in cold-water fish culture.

The future of plant based green carbon dots as cancer Nanomedicine: From current progress to future Perspectives and beyond

BACKGROUND

The emergence of carbon dots (CDs) as anticancer agents had sparked a transformation in cancer research and treatment strategies. These fluorescent CDs, initially introduced in the early 2000 s, possess exceptional biocompatibility, tunable fluorescence, and surface modification capabilities, positioning them as promising tools in biomedical applications.

AIM OF REVIEW

The review encapsulates the transformative trajectory of green CDs as future anticancer nanomedicine, poised to redefine the strategies employed in the ongoing fight against cancer.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The versatility of CDs was rooted in their various synthesis approaches and sustainable strategies, enabling their adaptability for diverse therapeutic uses. In vitro studies had showcased CDs' selective cytotoxicity against cancer cells while sparing healthy counterparts, forming the basis for targeted therapeutic potential. This selectivity had been attributed to the reactive oxygen species (ROS) generation, which opened avenues for targeted interventions. The role of CDs in combination therapies, synergizing with chemotherapy, radiotherapy, and targeted approaches was then investigated to heighten their anticancer efficacy. Notably, in vivo studies highlight CDs' remarkable biocompatibility and minimal side effects, endorsing their translational promise. Integration with conventional cancer treatments such as chemotherapy, radiotherapy, and immunotherapy amplified the versatility and effectiveness of CDs. The exploration of CDs' applications in photo-induced treatments further solidified their significance, positioning them as photosensitizers (PS) in photodynamic therapy (PDT) and photothermal agents (PA) in photothermal therapy (PTT). In PDT, CDs triggered the generation of ROS upon light exposure, facilitating cancer cell elimination, while in PTT, they induced localized hyperthermia within cancer cells, enhancing therapeutic outcomes. In vitro and in vivo investigations validated CDs' efficacy in PDT and PTT, affirming their potential for integration into combination therapies. Looking ahead, the future of CDs in anticancer treatment encompasses bioavailability, biocompatibility, synergistic treatments, tumor targeting, artificial intelligence (AI) and robotics integration, personalized medicine, and clinical translation. This transformative odyssey of CDs as future anticancer agents is poised to redefine the paradigm of cancer treatment strategies.

Bisphenol A Induces Reactive Oxygen Species Production and Apoptosis-Related Gene Expression in Pacific Red Snapper Lutjanus peru Leukocytes

Bisphenol A is one of the most used components of the polycarbonate plastic industry in the word. This contaminant has disrupting effect in cells in in vitro and in vivo in fish. This study evaluated for the first time the cytotoxicity, oxidative stress and apoptosis induced by bisphenol A (BPA) in head-kidney and spleen leukocytes isolated from Pacific red snapper Lutjanus peru. Head-kidney and spleen leukocytes were exposed to 100, 1000 and 10,000 µg/mL of BPA at 2 and 24 h. Results showed cytotoxicity of BPA at 1000 and 10,000 µg/mL. Cell viability > 80% was observed in leukocytes exposed to 100 µg/mL for 2 h; thus, this concentration was selected for the remainder of the study. Reactive oxygen species (ROS) production, analyzed by DCF-DA and NBT assays, significantly increased in those leukocytes exposed to BPA compared to controls after 2 or 24 h. Superoxide dismutase and catalase activities increased in head-kidney leukocytes after 24 h of BPA exposure. Apoptosis was inferred from caspase (casp-1 and casp-3), granzyme A (granz-A) and perforin 1 (perf-1) gene expression, which was significantly up-regulated, at 2 h BPA exposure in head-kidney leukocytes, and from granz-A and perf-1, which were up-regulated, after 24 h BPA exposure in spleen leukocytes. Short cytoplasmic prolongations and membrane blebs, suggestive of apoptosis, were observed by scanning electron microscopy. These data suggest that BPA at 100 µg/mL induces cytotoxicity, oxidative stress, apoptosis in Pacific red snapper head-kidney and spleen leukocytes.

Application of the Fpg-modified comet assay on three-spined stickleback in freshwater biomonitoring: toward a multi-biomarker approach of genotoxicity

Aquatic species are exposed to a wide spectrum of substances, which can compromise their genomic integrity by inducing DNA damage or oxidative stress. Genotoxicity biomarkers as DNA strand breaks and chromosomal damages developed on sentinel species have already proved to be relevant in aquatic biomonitoring. However, these biomarkers do not reflect DNA oxidative lesions, i.e., the 8-oxodG, recognized as pre-mutagenic lesion if not or mis-repaired in human biomonitoring. The relevance to include the measure of these lesions by using the Fpg-modified comet assay on erythrocytes of the three-spined stickleback was investigated. An optimization step of the Fpg-modified comet assay considering enzyme buffer impact, Fpg concentration, and incubation time has been performed. Then, this measure was integrated in a battery of genotoxicity and cytotoxicity biomarkers (considering DNA strand breaks, DNA content variation, and cell apoptosis/necrosis and density) and applied in a freshwater monitoring program on six stations of the Artois Picardie watershed (3-week caging of control fish). These biomarkers allowed to discriminate the stations regarding the genotoxic potential of water bodies and specifically by the measure of oxidative DNA lesions, which seem to be a promising tool in environmental genotoxicity risk assessment.

Effects of heatwave events on the seagrass-dwelling crustacean Pandalus latirostris in a subarctic lagoon

Heatwaves often cause mass mortality of organisms in seagrass areas, and they eventually alter some ecological functions of seagrass ecosystems. In subarctic regions, however, the effects of heatwaves on seagrass areas are still unclear. In a subarctic lagoon of northern Japan, we examined the effects of heatwaves on the Hokkai shrimp, Pandalus latirostris, a commercially exploited species distributed in seagrass areas of northern Japan and eastern Russia. A long-term survey of the surface water temperature in the lagoon clarified a gradual increase in the frequency and intensity of heatwave events since 1999. Surveys of the water temperature at a seagrass area in the lagoon during summer have also demonstrated that the maximum water temperature had been exceeding 25 °C, unusually high for this location, regardless of water depth. These results indicate that the effects of heatwaves in seagrass areas in a subarctic region had become as severe as those in tropical and temperate regions. We also experimentally evaluated the effects of this unusually high water temperature (25 °C) on the survival of P. latirostris by changing the length of exposure time. Some individuals suffered damage to their intestinal mucosal structure after exposure for 12 h or longer, and all individuals died after exposure for 120 h. Our results suggest that heatwaves possibly cause mass mortality in P. latirostris in the following sequence: heat stress, damage to the intestinal epithelial mucosal structure, degradation of nutrient absorption and immunological function of the intestine, energy deficiency and disease infection, and finally mortality. This study, conducted in subarctic closed waters, concludes that it is essential to become familiar with not only trends in heatwaves but also the intermittent occurrence of unusually high water temperature in seagrass areas in order to better understand the process of mortality of organisms that inhabit these ecosystems.

Monitoring of Mycotoxigenic Fungi in Fish Farm Water and Fumonisins in Feeds for Farmed Colossoma macropomum

This study aimed to evaluate the occurrence of mycotoxigenic fungi in fish farm water and mycotoxins in feeds for farmed tambaqui (Colossoma macropomum). A total of 40 samples of freshwater from fish farms and 16 samples of feed were collected and analyzed for microbiology. A total of five species of free-living fungi were identified in fish farms: Aspergillus fumigatus, Penicillium citrinum, P. implicatum, Fusarium oxysporum and Alternaria alternata. These fungi species were counted in water samples at 35.14 CFU mL-1 and 24.69 CFU mL-1 in the dry seasons. In all fish farms, there was a higher abundance of fungi species in the rainy season. During visits to the fish farmers, it was possible to verify poor feed storage conditions. Concerning mutations in blood cells, in tambaqui (C. macropomum), a total of 159 anomalies were found, and in Leptodactylus petersii, 299 anomalies were found, with higher incidences in conditions above 1.0 CFU mL-1 in log10(x+1) fungi and in the rainy season. The occurrence of mycotoxicological contamination was confirmed in 81.25% of the analyzed samples. The quantified mycotoxin was Fumonisins B1 + B2 (375 to 1418 μg kg-1). Pearson's correlation analysis showed a significant positive correlation between Fumonisins and feed samples (r = 0.83). There was also a significant positive correlation between the abundance of fungi in water and the quantification of Fumonisins (r = 0.79). Based on the results obtained, it can be concluded that free-living fungi can be used as bioindicators of water quality in fish farms. Consequently, the lack of good management practices caused microbiological contamination of the aquatic environment.

Toxicological mechanism of ammonia-N on haematopoiesis and apoptosis of haemocytes in Litopenaeus vannamei

Ammonia, as an important pollutant, contributed to the reduction of immunity, disruption of physiology in animals. RNA interference (RNAi) was performed to understand the function of astakine (AST) in haematopoiesis and apoptosis in Litopenaeus vannamei under ammonia-N exposure. Shrimps were exposed to 20 mg/L ammonia-N from 0 to 48 h with injection of 20 μg AST dsRNA. Further, shrimps were exposed to 0, 2, 10 and 20 mg/L ammonia-N also from 0 to 48 h. The results showed that the total haemocytes count (THC) decreased under ammonia-N stress and the knockdown of AST resulted in a further decrease of THC, suggesting that 1) the proliferation was decreased through the reduction of AST and Hedgehog, the differentiation was interfered by Wnt4, Wnt5 and Notch, and the migration was inhibited by the decrease of VEGF; 2) oxidative stress was induced under ammonia-N stress, leading to the increase of DNA damage with the up-regulated gene expression of death receptor, mitochondrial and endoplasmic reticulum stress pathways; 3) the changes of THC resulted from the decrease of proliferation, differentiation and migration of haematopoiesis cells and the increase of apoptosis of haemocytes. This study helps to deepen our understanding of risk management in shrimp aquaculture.

Additive effects of microplastics on accumulation and toxicity of cadmium in male zebrafish

Microplastics (MPs) have emerged as contaminants of concern because of their ubiquitous presence in almost all aquatic environments. The ecological effects of MPs are complex and depend on multiple factors including their age, size and the ecological matrix. There is an urgent need for multifactorial studies to elucidate their impacts. We measured the effects of virgin and naturally aged MPs, alone, pretreated with cadmium (Cd), or in combination with ionic Cd, on the bioaccumulation of Cd, metallothionein expression, behavior, and histopathology of adult zebrafish (Danio rerio). Zebrafish were exposed to virgin or aged polyethylene MPs (0.1% MPs enriched diets, w/w) or waterborne Cd (50 μg/L) or a combination of the two for 21 days. There was an additive interaction between water-borne Cd and MPs on bioaccumulation in males but not in females, Cd accumulation increased by twofold when water-borne Cd and MPs were combined. Water-borne Cd significantly induced higher levels of metallothionein compared to MPs pre-exposed to Cd. However, Cd-treated MPs caused greater damage to the intestine and liver compared to untreated MPs suggesting that bound Cd could be released or modulate MPs toxicity. We also showed that co-exposure to water-borne Cd and MPs increased anxiety in the zebrafish, compared with water-borne Cd alone, suggesting using microplastics as a vector may increase toxicity. This study demonstrates that MPs can enhance the toxicity of Cd, but further study is needed to elucidate the mechanism.

Hypoxia stress induces hepatic antioxidant activity and apoptosis, but stimulates immune response and immune-related gene expression in black rockfish Sebastes schlegelii

Dissolved oxygen concentrations both in the open ocean and coast have been declining due to the interaction of global climate change and human activity. Fish have evolved different adaptative strategies to cope with possibly damage induced by hypoxic environments. Black rockfish as important economic fish widely reared in the offshore sea cage, whereas related physiological response subject to hypoxia stress remained unclear. In this study, hepatic anti-oxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px]), aminotransferase (AST) and alanine aminotransferase (ALT) activities, lipid peroxidation (LPO), malondialdehyde (MDA) and glutathione (GSH) content, immunological parameters and the expression of apoptosis (bax, bcl2, p53, caspase3, xiap) and immune-related genes (c3, il-1β, ccl25, saa, hap, isg15) of black rockfish were determined during hypoxia and reoxygenation to illustrate the underlying defense response mechanisms. Results showed that hypoxia stress remarkably increased hepatic LPO and MDA content, AST and ALT activity and proportion of pyknotic nucleus. Hepatic SOD, CAT and GSH-Px activity manifested similar results, whereas GSH levels significantly decreased under hypoxia stress. The apoptosis rate of hepatocyte increased during hypoxia stress and reoxygenation. Meanwhile, p53, caspase3, bax and xiap mRNAs and bax/bcl2 rations were significantly up-regulated under hypoxia stress. However, bcl2 mRNA was significantly down-regulated. Interestingly, hypoxia stress significantly increased NBT-positive cell percent, phagocytic index, respiratory burst and ACH50 activity, and lysozyme activity. The mRNA levels of c3, ilβ, ccl25, saa, hap and isg15 were significantly up-regulated in the liver, spleen and head-kidney under hypoxia stress. The above parameters recovered to normal status after reoxygenation for 24 h Thus, hypoxia stress impairs hepatic antioxidant capacity, induces oxidative damage and apoptosis via the xiap-p53-bax-bcl2 and the caspase-dependent pathways, but enhances host immunity by regulating nonspecific immune indices and related genes expression to maintain homeostasis in black rockfish. These findings will help fully understand the hypoxia tolerance mechanisms of black rockfish and provide more data for offshore open ocean farming.

Nigericin treatment activates endoplasmic reticulum apoptosis pathway in goldfish kidney leukocytes

Nigericin has been reported to induce apoptosis and pyroptosis in mammalian models. However, the effects and mechanism underlying the immune responses of teleost HKLs induced by nigericin remain enigmatic. To decipher the mechanism after nigericin treatment, the transcriptomic profile of goldfish HKLs was analyzed. The results demonstrated that a total of 465 differently expressed genes (DEGs) with 275 up-regulated and 190 down-regulated genes were identified between the control and nigericin treated groups. Among them, the top 20 DEG KEGG enrichment pathways were observed including apoptosis pathways. In addition, the expression level of selected genes (ADP4, ADP5, IRE1, MARCC, ALR1, DDX58) by quantitative real-time PCR showed a significant change after treatment with nigericin, which was generally identical to the expression patterns of the transcriptomic data. Furthermore, the treatment could induce cell death of HKLs, which was confirmed by LDH release and annexin V-FITC/PI assays. Taken together, our results support the idea that nigericin treatment might activate the IRE1-JNK apoptosis pathway in goldfish HKLs, which will provide insights into the mechanisms underlying HKLs immunity towards apoptosis or pyroptosis regulation in teleosts.

Mercury Induced Tissue Damage, Redox Metabolism, Ion Transport, Apoptosis, and Intestinal Microbiota Change in Red Swamp Crayfish (Procambarus clarkii): Application of Multi-Omics Analysis in Risk Assessment of Hg

As one of the most toxic elements, mercury (Hg) is a widespread toxicant in aquatic environments. Crayfish are considered suitable for indicating the impact of heavy metals on aquatic crustaceans. Nevertheless, Hg toxicity on Procambarus clarkii is largely unknown. In this research, the acute Hg-induced alterations of biochemical responses, histopathology, hepatopancreatic transcriptome, and intestinal microbiome of Procambarus clarkii were studied. Firstly, Hg induced significant changes in reactive oxygen species (ROS) and malonaldehyde (MDA) content as well as antioxidant enzyme activity. Secondly, Hg exposure caused structural damage to the hepatopancreas (e.g., vacuolization of the epithelium and dilatation of the lumen) as well as to the intestines (e.g., dysregulation of lamina epithelialises and extension of lamina proprias). Thirdly, after treatment with three different concentrations of Hg, RNA-seq assays of the hepatopancreas revealed a large number of differentially expressed genes (DEGs) linked to a specific function. Among the DEGs, a lot of redox metabolism- (e.g., ACOX3, SMOX, GPX3, GLO1, and P4HA1), ion transport- (e.g., MICU3, MCTP, PYX, STEAP3, and SLC30A2), drug metabolism- (e.g., HSP70, HSP90A, CYP2L1, and CYP9E2), immune response- (e.g., SMAD4, HDAC1, and DUOX), and apoptosis-related genes (e.g., CTSL, CASP7, and BIRC2) were identified, which suggests that Hg exposure may perturb the redox equilibrium, disrupt the ion homeostasis, weaken immune response and ability, and cause apoptosis. Fourthly, bacterial 16S rRNA gene sequencing showed that Hg exposure decreased bacterial diversity and dysregulated intestinal microbiome composition. At the phylum level, there was a marked decrease in Proteobacteria and an increase in Firmicutes after exposure to high levels of Hg. With regards to genus, abundances of Bacteroides, Dysgonomonas, and Arcobacter were markedly dysregulated after Hg exposures. Our findings elucidate the mechanisms involved in Hg-mediated toxicity in aquatic crustaceans at the tissue, cellular, molecular as well as microbial levels.

PacBio Full-Length and Illumina Transcriptomes of the Gill Reveal the Molecular Response of Corbicula fluminea under Aerial Exposure

Air exposure is a common stress for Corbicula fluminea, an economically important freshwater shellfish consumed in China, during aquaculture and transportation. However, little is known about its molecular responses to air exposure. Therefore, this study used a combination of PacBio full-length and Illumina transcriptomes to investigate its molecular responses to air exposure. A total of 36,772 transcripts were obtained using PacBio sequencing. Structural analysis identified 32,069 coding sequences, 1906 transcription factors, 8873 simple sequence repeats, and 17,815 long non-coding RNAs. Subcellular localization analysis showed that most transcripts were located in the cytoplasm and nucleus. After 96-h of air exposure, 210 differentially expressed genes (DEGs) in the gill were obtained via Illumina sequencing. Among these DEGs, most of the genes related to glycolysis, tricarboxylic acid cycle, lipid metabolism, and amino acid metabolism were upregulated. Additionally, many DEGs associated with immunity, cytoskeleton reorganization, autophagy, and ferroptosis were identified. These findings indicated that metabolic strategy change, immune response, cytoskeleton reconstruction, autophagy, and ferroptosis might be the important mechanisms that C. fluminea use to cope with air exposure. This study will enrich the gene resources of C. fluminea and provide valuable data for studying the molecular mechanisms coping with air exposure in C. fluminea and other freshwater mollusks.

Oxidative stress, autophagy, and apoptosis induced by doxycycline in loach fin cells in vitro

Cytotoxicity, molecular function disorder, mitophagy, and apoptosis were studied in loach fin cells in vitro after exposure to doxycycline (DOX). The semi-lethal concentration of DOX in loach cells was calculated as 668.96 ± 2.83 mol/L. Loss of cell viability and increases in vacuoles and autolysosomes were evident in cells exposed to DOX at 200 and 400 μmol/L, and apoptotic bodies occurred at 600 μmol/L. In addition, Superoxide Dismutase (SOD), catalase (CAT), Na⁺-K⁺-ATPase, and Ca²⁺-ATPase activities increased significantly in cells exposed to 200 μmol/L DOX, and dose-dependent inhibitory effects on activities were observed in cells exposed to 400 and 600 μmol/L DOX. Quantitative gene expression showed that 400 and 600 μmol/L DOX could induce caspase-3- and caspase-8-mediated apoptosis as well as caspase-activated DNase in loach cells. Transcriptome sequencing in DOX vs. control groups found 16,288 differentially expressed genes, among which protein binding (2633, 31.91%) was the most significant in Gene Ontology terms. Furthermore, 11,930 genes were enriched in 298 Kyoto Encyclopedia of Genes and Genomes (KEGG)pathways. The top three upregulated pathways included "lysosome", "protein processing in endoplasmic reticulum", and "proteasome". FPKM analysis indicated that most genes associated with autophagy and in "protein processing in the endoplasmic reticulum", "TNF signaling pathway", and "NF-kappa B signaling pathway" were upregulated. This suggests that at lower concentrations, DOX induces reactive oxidative species (ROS) in loach fin cells to reduce cell proliferation. ROS in turn stimulate oxidant stress, ion excretion capability and mitophagy to maintain cell homeostasis. Apoptosis was induced in cells subjected to higher concentrations of DOX. The transcriptome data and pathways determined in this study will provide a foundation for the analysis of DOX toxicity in loach cells, which must be examined thoroughly to further understand the cytotoxic mechanism of antibiotics in fish cells.

Magnetic nanoparticles-induced neurotoxicity and oxidative stress in brain of rainbow trout: Mitigation by ulexite through modulation of antioxidant, anti-inflammatory, and antiapoptotic activities

The prevalent exposition of metallic nanoparticles (MNPs) to the aquatic medium and their negative influence on human life is one of the major concerns global. Stress mechanization, as a non-specific and pervasive response, involves all physiological systems, particularly the closely interconnected neuroendocrine and immune systems. In this study, which was designed to obtain more data on the biological effects of ulexit, which prevents oxidative DNA damage by protecting against toxicity damage and offers new antioxidant roles. The concomitant use of ulexite (UX, as 18.75 mg/l) as a natural therapeutic agent against exposure to magnetic nanoparticles (Fe₃O₄-MNPs/0.013 ml/l) on Oncorhynchus mykiss was investigated for 96 h. The brain tissues were taken at the 48th and 96th hours of the trial period, the effects on neurotoxic, pro-inflammatory cytokine genes, antioxidant immune system, DNA and apoptosis mechanisms were analyzed. In the present study, it was determined that AChE activity and BDNF level in the brain tissue decreased over time in the Fe₃O₄-MNPs group compared to the control, and UX tried to depress this inhibition. While inhibition was determined in antioxidant system biomarkers (SOD, CAT, GPx, and GSH values), an induction was observed in lipid peroxidation indicators (MDA and MPO values) in Fe₃O₄-MNPs applied group. The same group data showed that TNF-α, IL-6, 8-OHdG and caspase-3 levels were increased, but Nrf-2 levels were decreased. The alterations in all biomarkers were found to be significant at the p < 0.05 level. In general, it was determined that Fe₃O₄-MNPs caused stress in O. mykiss and UX exhibited a positive effect on this stress management.

Grass carp (Ctenopharyngodon idella) DYRK2 modulates cell apoptosis through phosphorylating p53

In mammals, DYRK2 increases p53 phosphorylation level by interacting with it and then promotes cell apoptosis. However, the function of fish DYRK2 has not yet been elucidated. In this paper, we cloned and identified the coding sequence (CDS) of a grass carp DYRK2 (CiDYRK2) which is 1773 bp in length and encodes 590 amino acids. SMART predictive analysis showed that CiDYRK2 possesses a serine/threonine kinase domain. Subsequently, we used the dsRNA analog polyinosinic-polycytidylic acid (poly (I:C) and Grass carp reovirus (GCRV) to stimulate grass carp and CIK cells for different times and found that CiDYRK2 mRNA was significantly up-regulated both in fish tissues and cells. To explore the function of CiDYRK2, we carried out overexpression and knockdown experiments of CiDYRK2 in CIK cells. Real-time quantitative PCR (Q-PCR), TdT-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry were used to detect the ratio of BAX/BCL-2 mRNA, the number of TUNEL positive cells, the proportion of Annexin V-positive cells respectively. The results showed that CiDYRK2 significantly up-regulated BAX/Bcl-2 mRNA ratio and increased the number of TUNEL-positive cells, as well as the proportion of Annexin V-positive cells. On the contrary, knock-down of CiDYRK2 significantly down-regulated BAX/Bcl-2 mRNA ratio in the cells. Therefore, CiDYRK2 promoted cell apoptosis. To study the molecular mechanism by which CiDYRK2 promoting cell apoptosis, subcellular localization and immunoprecipitation experiments were used to study the relationship between grass carp DYRK2 and the pro-apoptotic protein p53. The results showed that CiDYRK2 and Cip53 were located and co-localized in the nucleus. Co-immunoprecipitation experiment also showed that CiDYRK2 and Cip53 can bind with each other. We further found that DYRK2 can increase the phosphorylation level of p53. In a word, our results showed that grass carp DYRK2 induces cell apoptosis by increasing the phosphorylation level of p53.

Potential mechanisms of Na+/K+-ATPase attenuation by heat and pesticides co-exposure in goldfish: role of cellular apoptosis, oxidative/nitrative stress, and antioxidants in gills

In this study, we examined the dose-dependent effects of an environmentally relevant pesticide cocktail (metalachlor, linuron, isoproturon, tebucanazole, aclonifen, atrazine, pendimethalin, and azinphos-methyl) and temperature change (22 vs. 32 °C for 4-week exposure) on Na⁺/K⁺-ATPase, 3-nitrotyrosine protein (NTP), dinitrophenyl protein (DNP), catalase (CAT), and superoxide dismutase (SOD) expressions in gills of goldfish (Carassius auratus). Histopathological analysis showed widespread damage to gill in elevated temperature (32 °C) and pesticide co-exposure groups, including fusion of secondary lamellae, club-shaped primary lamellae, rupture of epithelial layer, loss of normal architecture, and hemorrhaging. Immunohistochemical and qRT-PCR analyses showed significant decreases in Na⁺/K⁺-ATPase protein and mRNA expressions in gills exposed to higher temperature and pesticides; however, combined exposure to heat and pesticides significantly increases NTP, DNP, CAT, and SOD expressions. In situ TUNEL assay revealed elevated levels of apoptotic cells in response to combined exposure. Collectively, our results suggest the combined effects of heat and pesticide stress cause cellular damage, upregulate oxidative/nitrative stress biomarkers, and increase apoptotic cells, downregulate Na⁺/K⁺-ATPase expression in gills. This provides new evidence for oxidant/antioxidant-dependent mechanisms for downregulation of Na⁺/K⁺-ATPase expression in gills during combined exposure.

Exposure to Bisphenol A Caused Hepatoxicity and Intestinal Flora Disorder in Rats

Bisphenol A (BPA) is a globally utilized industrial chemical and is commonly used as a monomer of polycarbonate plastics and epoxy resins. Recent research reveals that BPA could cause potential adverse biological effects and liver dysfunction. However, the underlying mechanisms of BPA-induced hepatoxicity and gut dysbiosis remain unclear and deserve further study. In this study, male Sprague Dawley rats were exposed to different doses (0, 30, 90, and 270 mg/kg bw) of BPA by gavage for 30 days. The results showed that the high dose of BPA decreased superoxide dismutase (SOD), glutathione (GSH), and increased malondialdehyde (MDA) levels. Moreover, a high dose of BPA caused a significant increase in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C), while high-density lipoprotein cholesterol (HDL-C) was significantly decreased in BPA-treated rats. The gene expression of PGC-1α and Nrf1 were decreased in the liver of high doses of BPA-administrated rats, as well as the protein levels of SIRT1, PGC-1α, Nrf2, and TFAM. However, the protein expression of IL-1β was significantly increased in BPA-treated rats. In addition, BPA weakened the mitochondrial function of hepatocytes and promoted cell apoptosis in the liver by up-regulating the protein levels of Bax, cleaved-Caspase3, and cleaved-PARP1 while down-regulating the Bcl-2 in the liver. More importantly, a high dose of BPA caused a dramatic change in microbiota structure, as characterized at the genus level by increasing the ratio of Firmicutes to Bacteroidetes (F/B), and the relative abundance of Proteobacteria in feces, while decreasing the relative abundance of Prevotella_9 and Ruminococcaceae_UCG-014, which is positively correlated with the content of short-chain fatty acids (SCFAs). In summary, our data indicated that BPA exposure caused hepatoxicity through apoptosis and the SIRT1/PGC-1α pathway. BPA-induced intestinal flora and SCFA changes may be associated with hepatic damage. The results of this study provide a new sight for the understanding of BPA-induced hepatoxicity.

RNA-Seq and 16S rRNA Analysis Revealed the Effect of Deltamethrin on Channel Catfish in the Early Stage of Acute Exposure

Deltamethrin (Del) is a widely used pyrethroid insecticide and a dangerous material that has brought serious problems to the healthy breeding of aquatic animals. However, the toxicological mechanisms of Del on channel catfish remain unclear. In the present study, we exposed channel catfish to 0, 0.5, and 5 μg/L Del for 6 h, and analyzed the changes in histopathology, trunk kidney transcriptome, and intestinal microbiota composition. The pathological analyses showed that a high concentration of Del damaged the intestine and trunk kidney of channel catfish in the early stage. The transcriptome analysis detected 32 and 1837 differentially expressed genes (DEGs) in channel catfish trunk kidneys after exposure to 0.5 and 5 μg/L Del, respectively. Moreover, the KEGG pathway and GO enrichment analyses showed that the apoptosis signaling pathway was significantly enriched, and apoptosis-related DEGs, including cathepsin L, p53, Bax, and caspase-3, were also detected. These results suggested that apoptosis occurs in the trunk kidney of channel catfish in the early stage of acute exposure to Del. We also detected some DEGs and signaling pathways related to immunity and drug metabolism, indicating that early exposure to Del can lead to immunotoxicity and metabolic disorder of channel catfish, which increases the risk of pathogenic infections and energy metabolism disorders. Additionally, 16S rRNA gene sequencing showed that the composition of the intestinal microbiome significantly changed in channel catfish treated with Del. At the phylum level, the abundance of Firmicutes, Fusobacteria, and Actinobacteria significantly decreased in the early stage of Del exposure. At the genus level, the abundance of Romboutsia, Lactobacillus, and Cetobacterium decreased after Del exposure. Overall, early exposure to Del can lead to tissue damage, metabolic disorder, immunotoxicity, and apoptosis in channel catfish, and affect the composition of its intestinal microbiota. Herein, we clarified the toxic effects of Del on channel catfish in the early stage of exposure and explored why fish under Del stress are more vulnerable to microbial infections and slow growth.

Interactive effects of high temperature and pesticide exposure on oxidative status, apoptosis, and renin expression in kidney of goldfish: Molecular and cellular mechanisms of widespread kidney damage and renin attenuation

One of many noteworthy consequences of increasing societal reliance on pesticides is their predominance in aquatic environments. These pernicious chemicals interact with high temperatures from global climate change, heat waves, and natural variations to create unstable environments that negatively impact organisms' health. To understand these conditions, we examined the dose-dependent effects of environmentally relevant pesticide mixtures (metolachlor, linuron, isoproturon, tebuconazole, aclonifen, atrazine, pendimethalin, and azinphos-methyl) combined with elevated temperatures (22 control vs. 32°C for 4-week exposure) on renin, dinitrophenyl protein (DNP, an indicator of reactive oxygen species, ROS), 3-nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS), superoxidase dismutase (SOD, an antioxidant), and catalase (CAT, an antioxidant) expressions in the kidneys of goldfish (Carassius auratus). Histopathological analysis showed widespread damage to kidney tissues in high temperature and pesticide co-exposure groups, including rupture of the epithelial layer, hemorrhaging, and degeneration of tubular epithelium. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical analyses demonstrated significant declines in renin receptor-like mRNA and protein expressions in kidney tissues under combined exposure to high temperature and pesticides compared with controls; conversely, expression of DNP, NTP, SOD, and CAT increased in kidney tissues under the same conditions. Apoptotic cells were also increased in co-exposure groups as assessed by in situ terminal deoxynucleotidyl transferase dUTP nick labeling (TUNEL) assay. The enhanced apoptosis in kidneys of heat and pesticides co-exposed fish was associated with increased caspase-3 (a protease enzyme) mRNA levels. Our results demonstrated that high temperature and pesticides induced oxidative/nitrative stress (i.e., ROS/RNS), damaged tissues, increased cellular apoptosis, and suppressed renin expression in kidneys of goldfish.

Transcriptomic response in thermally challenged seahorses Hippocampus erectus: The effect of magnitude and rate of temperature change

Hippocampus erectus inhabiting the shallow coastal waters of the southern Gulf of Mexico are naturally exposed to marked temperature variations occurring in different temporal scales. Under such heterogeneous conditions, a series of physiological and biochemical adjustments take place to restore and maintain homeostasis. This study investigated the molecular mechanisms involved in the response of H. erectus to increased temperature using transcriptome analysis based on RNA-Seq technology. Data was obtained from seahorses after 0.5-h exposure to combinations of different target temperatures (26 °C: control, and increased to 30 and 33 °C) and rates of thermal increase (abrupt: < 5 min; gradual: 1-1.5 °C every 3 h). The transcriptome of seahorses was assembled de novo using Trinity software to obtain 29,211 genes and 30,479 transcripts comprising 27,520,965 assembled bases. Seahorse exposure to both 30 and 33 °C triggered characteristic processes of the cellular stress response, regardless of the rate of thermal change. The transcriptomic profiles of H. erectus suggest an arrest of muscle development processes, the activation of heat shock proteins, and a switch to anaerobic metabolism within the first 0.5 h of exposure to target temperatures to ensure energy supply. Interestingly, apoptotic processes involving caspase were activated principally in gradual treatments, suggesting that prolonged exposure to even sublethal temperatures results in the accumulation of deleterious effects that may eventually terminate in cellular death. Results herein validate 30 °C and 33 °C as potential upper limits of thermal tolerance for H. erectus at the southernmost boundary of its geographic distribution.

Transcriptomic responses and apoptosis in larval red drum (Sciaenops ocellatus) co-exposed to crude oil and ultraviolet (UV) radiation

Ultraviolet (UV) radiation can significantly increase the toxicity of polycyclic aromatic hydrocarbons (PAHs) in crude oil to early life stage (ELS) fishes through photo-induced /photo-enhanced toxicity. However, little is known about the sub-lethal effects and mechanisms of photo-induced PAH toxicity in ELS fishes. The present study investigated apoptosis and global transcriptomic effects in larval red drum (Sciaenops ocellatus) (24-72 h post-fertilization) following co-exposure to oil (0.29-0.30 μg/L ∑PAH₅₀) and UV. Apoptosis was quantified using the TUNEL assay, and transcriptomic effects were assessed using RNA sequencing analysis. Apoptotic fluorescence was greatest in the eyes and skin following 24 and 48 h co-exposure to oil and UV, indicating photo-induced toxicity. Consistent with these phenotypic responses, pathways associated with phototransduction, eye development, and dermatological disease were among the top predicted pathways impacted. The present study is the first to provide global transcriptomic analysis of UV and oil co-exposure in an ELS fish.

Biomarker responses in perch (Perca fluviatilis) under multiple stress: Parasite co-infection and multicomponent metal mixture exposure

Parasitic infections may cause damage to the host immune system (i.e. fish), thereby endangering its health and weakening its responses to other types of stressors. Therefore, exposure to different kinds of natural or anthropogenic stressors can lead to unexpected toxicity outcomes in aquatic organisms. This study examined the haematological, genotoxic and cytotoxic effects of the co-infection with the protozoan parasite (Trichodina sp.) and the pathogenic oomycete (Saprolegnia parasitica) in Perca fluviatilis alone and in combination with chemical stress (environmentally-relevant aqueous concentrations of metal mixtures). Haematological analyses such as red cell and white cell indices revealed that chemical and biological stressors, used singly and in combination, exerted adverse effects on fish health. Changes in haematological indices induced by exposure to each of the above-mentioned stressors separately and by combined exposure to all of them suggested the multiple stress-induced inflammation process in the exposed fish. The cytogenetic damage inflicted by the S. parasitica and Trichodina sp. co-infection and multiple stress was revealed in fish erythrocytes. This information is expected to contribute to the elucidation of how multiple stressors impact on responses of haematic indices, geno- and cytotoxicity endpoints in P. fluviatilis. Assessment of the risk associated with multiple stressors is expected to prove valuable for the effective aquatic environment management (Løkke et al., 2013 and references therein).

Evaluation of UV-B protective properties of leaves and seeds of Achyranthes aspera in Asian catfish Clarias batrachus (Linn.)

The ultraviolet-B (UV-B) radiation is harmful to the aquatic organisms. The UV-B protective properties of leaves and seeds of herb Achyranthes aspera were evaluated in Clarias batrachus. Fish were fed with four diets-EFL1, EFL2 containing 0.25 and 0.5% leaves, EFS containing 0.5% seeds and control, CF. After 83 days of feeding, fish were exposed to UV-B (157 µW/cm²) for 7 days at the rate of 15 min/day. One batch of fish in each treatment was kept unexposed. Significantly higher final weight was found in EFS followed by EFL2 and EFL1 treatments. It was higher in unexposed fish compared to the exposed ones. Among exposed fish, significantly higher lysozyme was found in EFS and myeloperoxidase in EFS and EFL2 compared to others. Nitric oxide synthase and superoxide dismutase levels were significantly higher in liver and head kidney of EFS diet fed fish compared to others. Thiobarbituric acid reactive substances (TBARS) and carbonyl protein levels were minimum in EFS followed by EFL2. The independent sample t-test showed that nitric oxide synthase was significantly higher and myeloperoxidase and TBARS levels were significantly lower in unexposed group compared to the exposed fish in respective treatment. There were up-regulations of TNF-α, iNOS, NF-kB, BAX, Cytochrome c, SOD-c, Caspase 3, Caspase 9, BCL2 in liver and head kidney of leaves and seeds incorporated diets fed fish compared to control. Supplementation of A. aspera seeds and leaves at 0.5% level in diets gave UV-B protection to the fish.

Evolutionary conservation of a regulative pathway of erythropoiesis in Poikilothermic vertebrates

Apoptosis, programmed cell death, plays a central role in haematopoiesis. Mature erythrocytes of non-mammalian vertebrates maintain a permanent nucleus; these cells can undergo apoptosis (eryptosis), as do other somatic cells of a given non-mammalian vertebrate. In this study, we have investigated the expression and subcellular distribution of Bcl-2, Bcl-X_L and Bax proteins in the maturation phases and after X-ray irradiation of nucleated erythrocytes of Torpedo marmorata and Caretta caretta and the effect of X-ray irradiation on nucleated circulating erythrocytes of Torpedo marmorata. The cellular distribution of proteins was detected in erythrocytes by using immunocytochemistry at light microscopy and immunoelectron microscopy. The electrophoretic separation and immunoblotting of pro- and anti-apoptotic proteins of immature and mature erythroid cells was performed too, after X-ray irradiation of torpedoes. The results of the immunocytochemical analyses show an increase, in the expression level of Bax in mature as compared to young erythrocytes and a corresponding decrease of Bcl-2 and Bcl-X_L. This maturation pattern of Bax, Bcl-2 and Bcl-X_L was abrogated in X-ray irradiated torpedo erythrocytes. On the basis of these observations, Bax, Bcl-2 and Bcl-X_L seems to play a role in the erythropoiesis of Torpedo marmorata Risso and in Caretta caretta. In conclusion, the same apoptotic proteins of somatic cells appear to be conserved in circulating nucleated erythrocytes thus suggesting to play a role in the maturation of these cells.

Toxicological assessment of low-dose bisphenol A, lead and endosulfan combination: chronic toxicity study in male rats

In the present study, toxic effects, both alone and combined, of bisphenol A (BPA), lead (Pb) and endosulfan (ES) in the low doses were investigated in rat liver and kidney functions. In the study, bisphenol A (BPA), lead (Pb) and endosulfan (ES) were chosen because although they are the chemicals people are most frequently exposed to, no combined toxic effect studies were conducted with these chemicals. Sixty-four male Wistar albino rats were used in the study, and they were randomly divided into eight groups (n = 8 per group); control, BPA (5 mg/kg), Pb (100 ppm), ES (0.61 mg/kg), BPA+Pb, BPA+ES, Pb+ES and BPA+P+ES. The rats were sacrificed after 65 days of treatment. Severe histopathological changes in the liver and kidney tissues were observed in the rats exposed to BPA+Pb+ES combination. Elevated malondialdehyde (MDA) in the liver and decreased superoxide dismutase activity (SOD) in the kidney tissue were detected in the BPA+Pb+ES group compared to those of the control group. It was found that serum alanine aminotransferase (ALT) and blood urea nitrogen (BUN) and creatinine (CREA) levels were higher in the BPA+Pb+ES combination group than the control group. Also, combined exposure of BPA, Pb and ES caused apoptotic cell numbers and inducible nitric oxide (iNOS) to increase in the liver and kidney tissues. The results of the present study suggested that the BPA, Pb and ES caused more dramatic changes to both histological architecture and cell apoptosis in the liver and kidney tissues when there was a combined exposure.

Alleviation of microcystin-LR-induced hepatic lipidosis and apoptosis in zebrafish by use of rice straw-derived biochar

Microcystin-LR (MC-LR), mainly released by Microcystis aeruginosa, is posing a tremendous risk to aquatic animals and human health. Meanwhile, biochar (BC) is gradually be used as a sustainable adsorbent to immobilize and remove water pollutants. In our study, we for the first time conducted a full-scale investigation on lipid metabolism and its regulation mechanism of female zebrafish (Danio rerio) exposed to 0, 10 μg/L MC-LR, 100 μg/L BC, and 10 μg/L MC-LR+ 100 μg/L BC. The results indicated that sub-chronic MC-LR exposure induced hepatic lipidosis and apoptosis, including the formation of lipid droplets, significantly elevation of hepatic triglyceride (TG) level as well as significant upregulated expression of lipogenesis-related genes (foxo1a, elovl5, pparγ) and pro-apoptotic genes (bax, casp3). Nevertheless, no significant alteration was observed in the single BC group and the combined exposure group, which indicated that BC may solely functioned as an absorbent agent to lower MC-LR bioaccumulation in zebrafish liver and alleviate MC-LR-induced hepatotoxicity. Our findings revealed that the utilization of rice straw-derived BC can adsorb and immobile MC-LR in the water, subsequently alleviated the MC-LR-induced hepatic lipidosis and apoptosis in female zebrafish. On the basis of fish health, it is urgent to explore the feasibility of using environmentally friendly materials like BC to adsorb pollutants in water.

Fish Paralog Proteins RNASEK-a and -b Enhance Type I Interferon Secretion and Promote Apoptosis

Type I interferon and apoptosis elicit multifaceted effects on host defense and various diseases, such as viral infections and cancers. However, the gene/protein network regulating type I interferon and apoptosis has not been elucidated completely. In this study, we selected grass carp (Ctenopharyngodon idella) as an experimental model to investigate the modulation of RNASEK on the secretion of type I interferon and apoptosis. We first cloned two paralogs RNASEK-a and -b in grass carp, defined three exons in each gene, and found the length of both coding regions is 306 bp with 73.27% of protein homology. The protein sequences of the two paralogs are highly conserved across species. Two proteins were mainly localized in early and late endosomes and endoplasmic reticulum. Further, quantitative real-time PCR demonstrated that dsRNA poly I:C and grass carp reovirus upregulated RNASEK-a and -b in grass carp cells and tissues. Overexpression of RNASEK-a and -b individually induced type I interferon expression and the phosphorylation of IRF3/IRF7 shown by Western blot and immunofluorescent staining, increased Bax/Bcl-2 mRNA ratio, DNA fragmentations, TUNEL-positive cells, and the proportion of Annexin V-positive signals in flow cytometry, and activated eIF2α, opposite to that observed when RNASEK-a and -b were knocked down in multiple cell types. Taken together, we claim for the first time that fish paralog proteins RNASEK-a and -b enhance type I interferon secretion and promote apoptosis, which may be involved in the phosphorylation of IRF3/IRF7 and eIF2α, respectively. Our study reveals a previously unrecognized role of RNASEK as a new positive regulator of type I interferon and apoptosis.

Effects of acute deltamethrin exposure on kidney transcriptome and intestinal microbiota in goldfish (Carassius auratus)

As a widely used synthetic pyrethroid insecticide, deltamethrin (DM) causes serious health problems to aquatic organisms. However, the comprehensive understanding of the adverse effect of DM on aquatic organisms has received limited attention. In this study, goldfish (Carassius auratus) were exposed to 0 (control group), 0.2 and 2 µg/L DM for 96 h. The kidney transcriptome and intestinal microbiota were investigated. Comparative transcriptome analysis identified 270 and 711 differentially expressed genes (DEGs) in goldfish kidneys after exposure to 0.2 and 2 µg/L DM, respectively. KEGG pathway analysis revealed that the apoptosis pathway was markedly regulated and the regulation of programmed cell death was significantly enriched by the GO analysis. Several apoptosis-related genes including cathepsin L and cytochrome c were also detected. These results indicated that apoptosis occurred in the goldfish kidney after acute exposure to sublethal concentration of DM. Besides, some immune and drug metabolism-related DEGs were identified, indicating that exposure to DM caused immunotoxicity and metabolic disruption in goldfish. Additionally, 16 S rRNA gene sequencing analysis revealed a remarkable alteration in the composition of the intestinal microbial community of DM-treated goldfish. At the phylum level, the abundance of Proteobacteria, Firmicutes and Fusobacteria was increased, whereas the abundance of Bacteroidetes was reduced significantly after DM exposure. At the genus level, the abundance of Aeromonas, Cetobacterium, Dielma and Pseudorhodobacter was reduced, whereas Akkermansia was increased after DM exposure. In summary, exposure to DM could induce apoptosis and immunotoxicity in goldfish kidneys and affect the composition of the intestinal microbiota in goldfish. This study provides a comprehensive analysis of the adverse effect of DM exposure on the goldfish and will be helpful for understanding the toxicological mechanisms of DM in fish.

Fish out of water: Genomic insights into persistence of rainbowfish populations in the desert

How populations of aquatic fauna persist in extreme desert environments is an enigma. Individuals often breed and disperse during favorable conditions. Theory predicts that adaptive capacity should be low in small populations, such as in desert fishes. We integrated satellite-derived surface water data and population genomic diversity from 20,294 single-nucleotide polymorphisms across 344 individuals to understand metapopulation persistence of the desert rainbowfish (Melanotaenia splendida tatei) in central Australia. Desert rainbowfish showed very small effective population sizes, especially at peripheral populations, and low connectivity between river catchments. Yet, there was no evidence of population-level inbreeding and a signal of possible adaptive divergence associated with aridity was detected. Candidate genes for local adaptation included functions related to environmental cues and stressful conditions. Eco-evolutionary modeling showed that positive selection in refugial subpopulations combined with connectivity during flood periods can enable retention of adaptive diversity. Our study suggests that adaptive variation can be maintained in small populations and integrate with neutral metapopulation processes to allow persistence in the desert.

Molecular Identification of Anion Exchange Protein 3 in Pacific White Shrimp (Litopenaeus vannamei): mRNA Profiles for Tissues, Ontogeny, Molting, and Ovarian Development and Its Potential Role in Stress-Induced Gill Damage

Bicarbonate (HCO3 -) transport mechanisms play an essential role in the acid-base homeostasis of aquatic animals, and anion exchange protein 3 (AE3) is a membrane transport protein that exchanges Cl-/HCO3 - across the cell membrane to regulate the intracellular pH. In this study, the full-length cDNA of AE3 (Lv-AE3) was obtained from the Pacific white shrimp (Litopenaeus vannamei). The Lv-AE3 cDNA is 4,943 bp in length, contains an open reading frame of 2,850 bp, coding for a protein of 949 amino acids with 12 transmembrane domains. Lv-AE3 shows high sequence homology with other AE3 at the protein level. Lv-AE3 mRNA was ubiquitously detected in all tissues selected, with the highest expression level in the gill, followed by the ovary, eyestalk and brain. By in situ hybridization, Lv-AE3-positive cells were shown predominant localization in the secondary gill filaments. The expression levels of Lv-AE3 were further investigated during the essential life processes of shrimp, including ontogeny, molting, and ovarian development. In this case, the spatiotemporal expression profiles of Lv-AE3 in L. vannamei were highly correlated with the activities of water and ion absorption; for example, increased mRNA levels were present after hatching, during embryonic development, after ecdysis during the molt cycle, and in the stage IV ovary during gonadal development. After low/high pH and low/high salinity challenges, the transcript levels of Lv-AE3 were reduced in the gill, while the cell apoptosis rate increased. In addition, knockdown of Lv-AE3 mRNA expression induced cell apoptosis in the gill, indicating a potential link between Lv-AE3 and gill damage. Altogether, this study thoroughly investigated the relationship between the mRNA expression profiles of Lv-AE3 and multiple developmental and physiological processes in L. vannamei, and it may benefit the protection of crustaceans from fluctuated aquatic environments.

Uncoupling Thermotolerance and Growth Performance in Chinook Salmon: Blood Biochemistry and Immune Capacity

Ocean warming and extreme sea surface temperature anomalies are threatening wild and domesticated fish stocks in various regions. Understanding mechanisms for thermotolerance and processes associated with divergent growth performance is key to the future success of aquaculture and fisheries management. Herein, we exposed Chinook salmon (Oncorhynchus tshawytscha) to environmentally relevant water temperatures (19–20 °C) approaching their upper physiological limit for three months and sought to identify blood biomarkers associated with thermal stress and resilience. In parallel, blood biochemical associations with growth performance were also investigated. Temperature stress-activated leukocyte apoptosis induced a minor immune response, and influenced blood ion profiles indicative of osmoregulatory perturbation, regardless of how well fish grew. Conversely, fish displaying poor growth performance irrespective of temperature exhibited numerous biomarker shifts including haematology indices, cellular-based enzyme activities, and blood clinical chemistries associated with malnutrition and disturbances in energy metabolism, endocrine functioning, immunocompetence, redox status, and osmoregulation. Findings provide insight into mechanisms of stress tolerance and compromised growth potential. Biochemical phenotypes associated with growth performance and health can potentially be used to improve selective breeding strategies.

Morphopathology and gill recovery of Atlantic salmon during the parasitic detachment of Margaritifera margaritifera

During the conservation aquaculture of the freshwater mussel Margaritifera margaritifera, fish health has become a concern due to the need of mussel larvae (glochidia) to parasitize the salmonid gills and metamorphose into juveniles. However, there is a lack of information about the impact on fish during the juvenile detachment and the subsequent gill healing. To evaluate the morphopathological changes and gill recovery after the parasitism of M. margaritifera, 51 Atlantic salmon fry (Salmo salar), infested with around 22 larvae/fish g, were necropsied during the synchronized detachment of the mussel juveniles, and gills were assessed by stereomicroscopy and by light and scanning electron microscopy. Salmon showed no clinical signs during the trial and gills recovered their normal morphology almost completely in a short time, suggesting a minimal impact on fish health after glochidiosis. In this sense, the non-erosive droplet detachment and the goblet cell hyperplasia favoured an effective gill remodelling mediated by apoptosis, polarization and cell shedding of the gill epithelia, providing insights to the defence, clearing and healing mechanisms of the gill. These morphopathological techniques could also be implemented to preserve fish welfare and to optimize the artificial breeding programmes of endangered freshwater mussels.

Upregulation Mitochondrial Carrier 1 (MTCH1) Is Associated with Cell Proliferation, Invasion, and Migration of Liver Hepatocellular Carcinoma

Among the primary causes of cancer-associated death in the world, liver hepatocellular carcinoma (LIHC) ranks the third. LIHC is defined as the sixth most frequently diagnosed carcinoma. The gene mitochondrial carrier 1 (MTCH1) is a protein-coding gene. Recent research suggests that MTCH1 may be associated with some diseases. Here, our study attempts to explore the role and implication of MTCH1 in LIHC. Kaplan Meier Plotter and GEPIA (Gene Expression Profiling Interactive Analysis) databases were employed to determine the expression of MTCH1 and its correlation with prognostic status in LIHC patients. For the first time, our results suggested that MTCH1 was aberrantly expressed in human pan-cancer and highly expressed in LIHC. Its high expression was closely associated with metastasis of tumor, stage of cancer, and poor survival of patients. Then, through enrichment analysis, MTCH1 was found to be closely related to RNA splicing in LIHC. Subsequently, we conducted a series of functional experiments. PCR data showed that LIHC cell lines and samples are highly expressed MTCH1. CCK-8 (Cell Counting Kit-8) assays and Transwell assays indicated that silencing MTCH1 certainly suppressed cell proliferation, migration, and invasion. These findings shed the clue that MTCH1 could be regarded as the potential prognosis biomarker of LIHC and a promising therapeutic target for LIHC.

Induction of apoptosis in SSN-1cells by Snakehead Fish Vesiculovirus (SHVV) via Matrix protein dependent intrinsic pathway

An increasing important area in immunology is the process cell death mechanism, enabling the immune system triggered thru extrinsic or intrinsic signals to effectively remove unwanted or virus infected cells called apoptosis. A recently isolated infectious Snakehead fish vesiculovirus (SHVV), comprising negative strand RNA and encoded viral matrix (M) proteins, is responsible for causing cytopathic effects in infected fish cells. However, the mechanism by which viral M protein mediates apoptosis has not been elucidated. Therefore, in the present experiments, it was investigated the regulatory potential of apoptosis signals during SHVV infection. By employing the model of SHVV infection in SSN-1 cells, the accelerated apoptosis pathway involves an intrinsic pathway requiring the activation of caspase-9 but not caspase-3 or -8. In the groups of infection (SHVV) or treatment (hydrogen peroxide) were induced apoptotic morphological changes and indicated the activation of the main caspases, i.e.; executioner caspase-3, initiators caspase-8 and caspase-9 using colorimetric assays. Turning to the role of viral M protein when it was overexpressed in SSN-1 cells, it was indicated that the viral M gene alone has the ability to induce apoptosis. To elucidate the mechanism of apoptosis in SSN-1 cells, the activation inhibitors of main caspases were used showing that inhibiting of caspase-3 or caspase-8 activation did not seize induction of apoptosis in virus-infected SSN-1 cells. However, the inhibiting of caspase-9 activation reduced significantly the apoptosis initiation process and sharply the expression of viral M gene, suggesting that SHVV plays a major role in the early induction of apoptosis by caspase-9. Interestingly, there were also differences in the mitochondrial membrane potential after the apoptotic induction of caspases, which confirm that caspase-9 is primarily responsible for the cleavage of caspases during apoptosis. Taken together, these findings can therefore be assumed that viral M protein induces apoptosis via the intrinsic apoptotic pathway in SHVV infecting SSN-1 cells.

Survival and malformations rates, oxidative status in early life stages of Cyprinus carpio due to exposure to environmentally realistic concentrations of paracetamol

Paracetamol (PCM) is among the most consumed analgesic and antipyretic drugs worldwide. Due to its high consumption, this drug has been reported ubiquitously on different water bodies, posing a real threat to aquatic organisms. Until now, several studies have pointed out that PCM may induce oxidative stress, histological damage and developmental disorders on different aquatic species. Nonetheless, there is still a huge knowledge gap about the toxic effects that PCM may induce in species of commercial interest such as the common carp Cyprinus carpio. The aim of this study was to evaluate survival and malformation rates induced by PCM (0.5 μg/L - 3.5 μg/L) in early life stages of common carp. Furthermore, oxidative stress biomarkers were evaluated at 72 and 96 h post fecundation. PCM reduced the survival rate of the embryos of up to 90%, as concentration increased. LC₅₀ and EC_50m were 1.29 μg/L and 2.84 μg/L, respectively. Biomarkers of cellular oxidation and antioxidant enzymes were modified in a concentration-dependent way with respect to the control group (p < 0.05). The main developmental alterations observed were lordosis, scoliosis, craniofacial malformations, hypopigmentation, growth retardation, pericardial edema and rachyschisis. These data indicate that environmentally realistic concentrations of PCM could be hazardous and affects the development in early stages of C. carpio. Moreover, our findings also indicate that C. carpio embryos may be a useful in vivo model to evaluate embryonic and teratogenic effects of drugs such as PCM.

Effects of elevated temperature on prooxidant-antioxidant homeostasis and redox status in the American oyster: Signaling pathways of cellular apoptosis during heat stress

Increasing seawater temperature affects growth, reproduction, development, and various other physiological processes in aquatic organisms, such as marine invertebrates, which are especially susceptible to high temperatures. In this study, we examined the effects of short-term heat stress (16, 22, 26, and 30 °C for 1-week exposure) on prooxidant-antioxidant homeostasis and redox status in the American oyster (Crassostrea virginica, an edible and commercially cultivated bivalve mollusk) under controlled laboratory conditions. Immunohistochemical and real-time quantitative PCR (qRT-PCR) analyses were performed to examine the expression of heat shock protein-70 (HSP70, a biomarker of heat stress), catalase (CAT, an antioxidant), superoxide dismutase (SOD, an antioxidant), dinitrophenyl protein (DNP, a biomarker of reactive oxygen species, ROS), and 3-nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS), in the gills and digestive glands of oysters. In situ TUNEL assay was performed to detect cellular apoptosis in tissues. Histological analysis showed an increase in mucus secretion in the gills and digestive glands of oysters exposed to higher temperatures (22, 26, and 30 °C) compared to control (16 °C). Immunohistochemical and qRT-PCR analyses showed significant increases in HSP70, DNP and NTP protein, and mRNA expressions in tissues at higher temperatures. Cellular apoptosis was also significantly increased at higher temperatures. Thus, heat-induced oxidative and nitrative stress likely occur due to overproduction of ROS and RNS. Interestingly, expression of CAT and SOD increased in oysters exposed to 22 and 26 °C, but was at or below control levels in the highest temperature exposure (30 °C). Collectively, these results suggest that elevated seawater temperatures cause oxidative/nitrative stress and induce cellular apoptosis through excessive ROS and RNS production, leading to inhibition of the antioxidant defense system in marine mollusks.

Embryo Buoyancy and Cell Death Gene Expression During Embryogenesis of Yellow-Tail Kingfish Seriola lalandi

In pelagic fish, embryo buoyancy is a noteworthy aspect of the reproductive strategy, and is associated with overall quality, survival, and further developmental success. In captivity, the loss of buoyancy of early embryos correlates with high mortality that might be related to massive cell death. Therefore, the aim of this study was to evaluate under captivity conditions the expression of genes related to the apoptosis process during the early embryonic development of the pelagic fish Seriola lalandi, and its relationship to the buoyancy of embryos. The relative expression of bcl2, bax-like, casp9, casp8, and casp3 was evaluated by RT-qPCR and FasL/Fas protein levels by western blot in five development stages of embryos sorted as floating or low-floating. All genes examined were expressed in both floating and low-floating embryos up to 24 h of development. Expression of the pro-apoptotic factors bax, casp9, casp8, and casp3 was higher in low-floating as compared with floating embryos in a developmental stage-specific manner. In contrast, there was no difference in expression of bcl2 between floating and low-floating embryos. Fas protein was detected as a single band in floating embryos without changes in expression throughout development; however, in low-floating embryos, three higher intensity reactive bands were detected in the 24-h embryos. Interestingly, FasL was only detected at 24-h in floating embryos, whereas in low-floating samples this ligand was present at all stages, with a sharp increase as development progressed. Cell death, as evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, was highly increased in low-floating embryos as compared to floating embryos throughout all developmental stages, with the highest levels observed during the gastrula stage and at 24 h. The results of this study suggest that an increase in cell death, probably associated with the intrinsic and extrinsic apoptosis pathways, is present in low-floating embryos that might explain their lower developmental potential under captivity conditions.

Identification of BAG5 from orange-spotted grouper (Epinephelus coioides) involved in viral infection

Bcl-2-associated athanogene 5 (BAG5) is a kind of molecular chaperone that can bind to the Bcl-2 and modulate cell survival. However, little is known about the functions of fish BAG5. In this study, we characterized a BAG5 homolog from orange-spotted grouper (Epinephelus coioides) gene (Ec-BAG5) and investigated its roles during viral infection. The Ec-BAG5 protein encoded 468 amino acids with four BAG domains, which shared high identities with reported BAG5. The highest transcriptional level of Ec-BAG5 was found in the peripheral blood lymphocyte (PBL). And the Ec-BAG5 expression were significantly up-regulated after red-spotted grouper nervous necrosis virus (RGNNV) or Lipopolysaccharide (LPS) stimulation in vitro. Furthermore, Ec-BAG5 overexpression could inhibited viral replication and the expression of viral genes (coat protein (CP) and RNA-dependent RNA polymerase (RdRp)). Also, overexpression of Ec-BAG5 significantly increased the expression of interferon pathway-related factors including interferon regulatory factor 3 (IRF3), interferon-stimulated gene 15 (ISG15), interferon-induced protein 35 (IFP35), myxovirus resistance gene 1 (Mx1) and inflammatory-related factors including tumor necrosis factor receptor-associated factor 6 (TRAF6), tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), as well as the activities of NF-κB, ISRE and IFN-1. These data indicate that Ec-BAG5 can affect viral infection through regulating the expression of IFN- and inflammation-related factors, which provide useful information to better understand the immune response against viral infection.

The Effects of Ozone on Atlantic Salmon Post-Smolt in Brackish Water-Establishing Welfare Indicators and Thresholds

Ozone is a strong oxidant, and its use in aquaculture has been shown to improve water quality and fish health. At present, it is predominantly used in freshwater systems due to the high risk of toxic residual oxidant exposure in brackish water and seawater. Here, we report the effects of ozone on Atlantic salmon (Salmo salar) post-smolts (~100 g), in a brackish water (12 ppt) flow-through system. Salmon were exposed to oxidation reduction potential concentrations of 250 mV (control), 280 mV (low), 350 mV (medium), 425 mV (high) and 500 mV (very high). The physiological impacts of ozone were characterized by blood biochemical profiling, histopathologic examination and gene expression analysis in skin and gills. Fish exposed to 425 mV and higher showed ≥33% cumulative mortality in less than 10 days. No significant mortalities were recorded in the remaining groups. The skin surface quality and the thickness of the dermal and epidermal layers were not significantly affected by the treatments. On the other hand, gill histopathology showed the adverse effects of increasing ozone doses and the changes were more pronounced in the group exposed to 350 mV and higher. Cases of gill damages such as necrosis, lamellar fusion and hypertrophy were prevalent in the high and very high groups. Expression profiling of key biomarkers for mucosal health supported the histology results, showing that gills were significantly more affected by higher ozone doses compared to the skin. Increasing ozone doses triggered anti-oxidative stress and inflammatory responses in the gills, where transcript levels of glutathione reductase, copper/zinc superoxide dismutase, interleukin 1β and interleukin were significantly elevated. Heat shock protein 70 was significantly upregulated in the skin of fish exposed to 350 mV and higher. Bcl-2 associated x protein was the only gene marker that was significantly upregulated by increasing ozone doses in both mucosal tissues. In conclusion, the study revealed that short-term exposure to ozone at concentrations higher than 350 mV in salmon in brackish water resulted in significant health and welfare consequences, including mortality and gill damages. The results of the study will be valuable in developing water treatment protocols for salmon farming.

Temperature-induced testicular germ cell loss and recovery in Nile tilapia Oreochromis niloticus

Water temperature is a critical external factor influencing gonadal development in fish. This research aimed to study the impact of elevated temperature on testicular germ cell survival and reproductive capacity of Nile tilapia. Male Nile tilapia were exposed to high temperatures of either 36 (HT1) or 37 °C (HT2) for 3000 degree-days (DD) and thereafter returned to the control temperature of 27 °C (CT) for 2200 DD. The deleterious effects on testicular germ and somatic cells were observed histologically, characterised by vacuolisation, atrophy and the loss of spermatogenic cells in testes with a more severe impact of HT2 compared to HT1. Interestingly, serum 11-ketotestosterone (11-KT) and testosterone (T) levels tended to be higher during the heat treatments than CT. Expression levels of germline-specific genes piwil1, piwil2 and nanos2 and Bcl-2 family genes, bcl-xLb and baxa were significantly reduced during the heat treatment compared to CT, more so in the HT2, while the levels of nanos3 and gfra1 transcripts were only significantly reduced in HT2, implying a significant loss of spermatogonial stem cell (SSC) and spermatogonia in HT2. The effect of HT2 is further evidenced by the significantly reduced sperm density and fertilisation rate compared to CT and HT1 at the end of the recovery period but complete sterility was not induced by HT2. Overall, the present study showed significant effects of HT2 on germ cell survival with histological changes in testes, reduced milt quality, increased 11-KT, and decreased expression of germline-specific genes, SSC marker genes and Bcl-2 family genes in testes which could therefore be potential target genes for sterilisation by genome editing.

Biochemical and molecular responses of cyprinids in two Mediterranean lacustrine ecosystems: Opportunities for ecological assessment and biomonitoring

Lacustrine ecosystems have been altered by accelerating pollution, excessive nutrient and organic load, water abstraction, and are susceptible to climate change. Hence, suggesting sensitive and reliable biomarkers for early assessments of their status is of urgent need. In this study, two freshwater commercial fish species, Cyprinus carpio (carp) and Carassius gibelio (prussian carp) from two lakes (i.e. Koronia and Volvi, Northern Greece) with different anthropogenic pressures were used and a battery of biochemical and molecular biomarkers related to stress response were analyzed in fish gills and liver. In parallel, water physicochemical parameters (T, DO, pH, conductivity, salinity), BOD₅ and nutrient (N-NO₃, N-NO₂, N-NH₄, P-PO₄) concentrations were measured. Results showed that Lake Koronia had higher conductivity and salinity values and N-NO₂ concentrations. Levels of Heat Shock Response (HSR), MAPK phosphorylation, protein carbonylation, lipid peroxidation products, Bax/Bcl-2 ratio, ubiquitination and caspases were increased in gills and liver of both fish species sampled from Lake Koronia in relation to those of Lake Volvi. Likewise, liver lipid content was increased in both fish species sampled from Lake Koronia compared to those sampled from Lake Volvi. The results indicate and reflect the higher environmental degradation that prevails in Lake Koronia ecosystem in comparison to that of Lake Volvi. The fish species studied showed different susceptibility depending on the biomarkers examined. In addition, our results from both examined species provide insight into the mechanisms involved in acclimatization to stressful environments and support the role of the studied biomarkers as sensitive and reliable tools for ecological assessments of lake ecosystems in biomonitoring studies.

Cordycepin-induced unfolded protein response-dependent cell death, and AKT/MAPK-mediated drug resistance in mouse testicular tumor cells

Testicular cancer is the most commonly diagnosed cancer in men at 15-44 years of age, and radical orchidectomy combined with chemotherapy is currently considered as the standard treatment. However, drugs resistance and side effects that impact the quality of life for patients with testicular cancer have not been markedly improved in recent decades. In this study, we characterized the pharmacological exacerbation of the unfolded protein response (UPR), which is an effective approach to kill testicular cancer cells, by carrying out a clustering analysis of mRNA expression profiles and the immunobloting examination of cordycepin-treated MA-10 cells. The UPR is executed in response to endoplasmic reticulum stress to complement by an apoptotic response if the defect cannot be resolved. Results showed that cordycepin significantly modulated FoxO/P15/P27, PERK-eIF2α (apoptotic), and the IRE1-XBP1 (adaptive) UPR pathways. Interestingly, a fraction of MA-10 cells survived after cordycepin treatment, the AKT, LC3 I/II, and MAPK signaling pathways were highly induced in attached cells as compared to the suspended cells, illustrating the drug resistance to cordycepin via activating AKT and MAPK pathways in MA-10 cells. In summary, PERK-eIF2α signaling pathway is required for pro-apoptotic UPR in MA-10 cell death following cordycepin treatment, suggesting a potential therapeutic application in treating testicular cancer. However, activation of AKT and MAPK pathways could possibly result in drug resistance to cordycepin in MA-10 cells.

Down-regulation expression of TGFB2-AS1 inhibits the proliferation, migration, invasion and induces apoptosis in HepG2 cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the leading cause of cancer mortality and without effective prognosis. Previous study has been confirmed that the abnormal expression of long non-coding RNAs (lncRNAs) TGFB2-AS1 was involved in tumorigenesis. However, the biological functions of TGFB2-AS1 in hepatocellular carcinoma (HCC) remain largely unclear.

OBJECTIVE

We comprehensively assess the clinical significance of TGFB2-AS1 and investigate the biological functions of TGFB2-AS1 on HCC HepG2 cells.

METHODS

We firstly confirmed the expression of TGFB2-AS1 between tumor and normal tissues using public available transcriptome data. We analyzed the clinical significance of TGFB2-AS1 using the TCGA HCC datasets. The biological functions of TGFB2-AS1 on HCC HepG2 cells were explored by multiple in vitro assays.

RESULTS

We found that TGFB2-AS1 was remarkably increased in HCC tissues (P = 0.00148) and exhibited a potential predictive marker for HCC, with an area under curve (AUC) of 0.708 (P = 0.0034) using the fifty pairs of matched HCC tissues of TCGA. Besides, higher expression of TGFB2-AS1 in HCC tissues was identified as being positively associated with advanced tumor (P = 0.012) and disease stage (P = 0.009) in 355 HCC cases using independent sample nonparametric test. Downregulation of TGFB2-AS1 expression significantly restrained proliferation (P < 0.01) and impaired colony formation (P < 0.05). Furthermore, TGFB2-AS1 depletion remarkably promoted the apoptosis of HepG2 cells (P < 0.05) and inhibited migration and invasion (P < 0.01).

CONCLUSION

Taken together, these findings suggested that TGFB2-AS1 might serve as a potential therapeutic target for HCC.

Glucocorticoid receptor in ayu (Plecoglossus altivelis): Genomic and non-genomic effects on monocytes/macrophages function

The glucocorticoid receptor (GR) is an important feedback regulator of the hypothalamic-pituitary-interrenal (HPI) axis. However, there are a limited number of studies focused on host-pathogen interactions in which an association between GR and immune response has been evaluated in monocytes/macrophages (MO/MФ) after being challenged with highly pathogenic bacteria. Here, we cloned the cDNA sequence of the glucocorticoid receptor (PaGR) gene from ayu fish. The PaGR transcript was expressed in all tissues, and changes in expression were observed in immune tissues and MO/MФ after live Vibrio anguillarum infection. Subsequently, PaGR was expressed and purified to prepare anti-PaGR antibodies. We analyzed the subcellular localization of PaGR. PaGR was expressed not only in the intracellular space but also in the plasma membrane. PaGR activation decreased the expression of pro-inflammatory cytokines and increased the expression of anti-inflammatory cytokines. However, PaGR activation suppressed the phagocytosis activity of V. anguillarum-infected ayu MO/MФ via a non-genomic pathway. Interestingly, PaGR activation could enhance MO/MФ bacterial killing capability and apoptosis. Therefore, PaGR may modulate the immune response in ayu MO/MФ by genomic and non-genomic pathways.

Laminarin enhances the quality of aged pig oocytes by reducing oxidative stress

Laminarin (LAM) is a β-glucan oligomer known to possess biological activities such as anticancer and antioxidant effects. This study explored the influence of LAM supplementation on in vitro aged porcine oocytes and the underlying mechanisms behind this influence. We found that LAM delayed the aging process and improved the quality of aged oocytes. LAM supplementation enhanced the subsequent developmental competence of aged oocytes during the in vitro aging process. The blastocyst formation rate was significantly increased in aged oocytes treated with 20 µg/ml LAM compared to non-treated aged oocytes (45.3% vs. 28.7%, P < 0.01). The mRNA levels of apoptosis-related genes, B cell lymphoma-2-associated X protein (Bax) and Caspase-3, were significantly lower in blastocysts derived from the LAM-treated aged oocytes during the in vitro aging process. Furthermore, the level of intracellular reactive oxygen species was significantly decreased and that of glutathione was significantly increased in aged oocytes following LAM treatment. Mitochondrial membrane potential was increased, and the activities of caspase-3 and cathepsin B were significantly reduced in the LAM-treated aged oocytes compared with the non-treated aged oocytes. Taken together, these results suggest that LAM is beneficial for delaying the aging process in porcine oocytes.