Search Results (63)

The gonadal development of Japanese eels (Anguilla japonica) plays a crucial role in the success of artificial breeding. Soy isoflavones, a class of phytoestrogens commonly found in aquafeeds, have shown potential in enhancing gonad development in fish. The present study evaluated the effects of dietary soy isoflavones on gonadal development, growth performance, histology, sex hormone levels, vitellogenin content, and expression of related genes in female Japanese eel broodstock. A 4-week feeding trial was conducted with 120 two-year-old female eels randomly assigned to four groups and fed diets containing 0 (C), 0.1 (L), 0.5 (M), and 0.9 (H) mg/g of soy isoflavones. The results indicated that gonadal development was enhanced in the M and H groups, as evidenced by a significantly higher gonadosomatic index (GSI) and increased oocyte cross-sectional area (CSA) in M group, and greater nutrient accumulation in both the M and H groups. The expression of er and cyp19a genes in the ovary was downregulated in the treatment groups, leading to decreased serum estradiol (E₂) and increased testosterone levels. Furthermore, hepatic vtg gene expression was upregulated in the M and H groups, though VTG protein content remained unchanged, suggesting an initiation of vitellogenesis at the transcriptional level. In conclusion, dietary soy isoflavones at 0.5–0.9 mg/g provide an effective pretreatment strategy to enhance early ovarian development in Japanese eel broodstock, potentially improving their responsiveness to subsequent hormonal induction in artificial breeding programs. Full article

Polyester microfibers (MF) are widespread in aquatic environments and increasingly recognized as an emerging factor affecting fish physiology. This study aimed to investigate the effects of intestinal accumulation of MF on gut tissue and cellular alterations, as well as on the HPG axis and oocyte maturation in adult female zebrafish. Adult female zebrafish were exposed to environmentally relevant concentrations of MF (1000 and 3000 particles/L) for 14 days to examine endocrine-regulated physiological and reproductive responses. For comparative reference, a bisphenol A (BPA) exposure group was included to contextualize endocrine-related responses. MF exposure resulted in intestinal accumulation. Gene expression analyses showed increased expression of vtg1 and esr2a, along with decreased expression of gnrh3, fshβ, lhβ, cyp17, and cyp19a1, indicating altered regulation of the HPG axis and steroidogenic pathways. Ovarian histology revealed alterations in oocyte development, especially at the higher MF concentration, indicating that MF can affect endocrine-regulated physiology and reproduction in fish. Together, these findings provide new evidence that intestinal accumulation of microfibers, along with associated histological and transcriptional alterations, elicits estrogen-responsive physiological patterns that influence HPG axis regulation and oocyte maturation in fish. Full article

The red swamp crayfish (Procambarus clarkii) is a globally important freshwater crustacean that exhibits pronounced sexual dimorphism, with males growing faster than females. However, the molecular mechanisms underlying sex differentiation in crustaceans remain poorly understood. In this study, Oxford Nanopore-based Direct RNA Sequencing (DRS) was employed to analyze the gonadal transcriptomes of male and female P. clarkii, identifying 20,001 previously unannotated genes and revealing extensive sex-specific differences in transcript structure, alternative splicing, and RNA modifications. Ovarian transcripts had shorter poly(A) tails and more frequent alternative splicing, while male gonads showed greater enrichment of m⁶A and psU modifications in the 3′ UTRs. qPCR validation confirmed the sex-biased expression of key candidate genes, including Dmrt7, FR, Fruitless, IAGBP, RDH, and Vtg. Collectively, these findings provide the first comprehensive epitranscriptomic landscape of P. clarkii gonads, underscoring the pivotal role of post-transcriptional regulation in sex determination and offering valuable insights for mono-sex breeding strategies in aquaculture. Full article

Endocrine-disrupting chemicals (EDCs) are widespread contaminants that interfere with hormonal signaling and compromise reproductive success in aquatic organisms. Vitellogenin (VTG) is one of the most widely established biomarkers of estrogenic exposure, especially in males and juveniles. However, evidence from multi-omics studies indicates that VTG induction occurs within broader transcriptional and regulatory networks, involving genes such as cyp19a1 (aromatase), cyp1a (cytochrome P4501A), and other stress-responsive genes, underscoring the complexity of endocrine disruption. This review focuses on nuclear receptor isoforms, including estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and androgen receptor (AR) variants. We examine the diversification of vtg gene repertoires across teleost genomes and epigenetic mechanisms, such as DNA methylation and microRNAs, that modulate sex-dependent sensitivity. In addition, we discuss integrative approaches that combine VTG with transcriptomic, epigenetic, and histological endpoints. Within the Adverse Outcome Pathway (AOP) and weight-of-evidence (WoE) frameworks, these strategies provide mechanistic links between receptor activation and reproductive impairment. Finally, we outline future directions, focusing on the development of sex-specific biomarker panels, the integration of omics-based data with machine learning, and advances in ecogenomics. Embedding molecular responses into ecological and regulatory contexts will help bridge mechanistic insights with environmental relevance and support sustainability goals such as SDG 14 (Life Below Water). Full article

The swimming crab is a commercially and nutritionally important marine resource with the highest catch volumes in Mexico occurring along the East Pacific coast. Among the Pacific species of the genus Callinectes, the blue crab C. arcuatus has the widest distribution and is found throughout the year. Its close resemblance to the well-studied Atlantic blue swimming crab (C. sapidus) makes it an excellent model for molecular reproductive studies in the Mexican Pacific. Using next-generation sequencing, this study aimed to characterize maturation-associated genes in an ovary–hepatopancreas transcriptome of C. arcuatus, with a particular focus on vitellogenin (Vtg) and its expression in the ovaries and hepatopancreas across different gonadal maturity stages. The transcriptome library generated from pooled samples produced 27,729 unigenes, of which, 196 (1.81%) were identified as reproduction-related genes. Notably, 33 of these genes, including the complete Vtg sequence, have not been previously reported in this species. Vtg expression was found to be tissue-specific, with levels in the hepatopancreas up to 13 orders of magnitude higher than in the ovary. In the hepatopancreas, Vtg expression increased exponentially from stage I to stage V of gonadal maturity, whereas in the ovaries, its expression showed the opposite trend. These findings highlight that the hepatopancreas, with its abundant nutrient reserves, serves as the primary site of Vtg expression and synthesis. Full article

Microplastics (MPs) are a growing environmental concern due to their ability to adsorb hazardous chemicals, such as estrogens, and be ingested by marine organisms. This study focuses on low-density polyethylene (LDPE), a polymer widely used in Kuwait, to assess its role as a carrier of endocrine-disrupting chemicals (EDCs), specifically estrogens. Biological effects were evaluated using biomarkers such as cytochrome P450 1A (CYP1A) and vitellogenin (Vtg) gene expression. Virgin LDPE MPs were exposed to influent and effluent from a wastewater treatment plant (WWTP) for four weeks to facilitate estrogen absorption. The MPs were then incorporated into fish feed pellets for dietary exposure experiments. Fish were divided into three treatment groups—exposed to either virgin MPs, WWTP-influent MPs, or WWTP-effluent MPs—and monitored over four weeks. The results showed that WWTP-exposed MPs carried detectable levels of estrogen, leading to physiological effects on yellowfin bream. Fish in the control group, which received MP-enriched diets without estrogen, experienced significant weight loss due to nutrient deprivation. In contrast, weight patterns in the treatment groups were influenced by estrogen exposure. The condition factor (CF) decreased across groups during the experiment but remained within acceptable health ranges. A significant reduction in the hepatosomatic index (HSI) was observed in the effluent-exposed group, likely due to lower estrogen levels reducing physiological stress. The findings confirm that LDPE MPs can act as carriers for estrogens, impairing fish growth and metabolism while disrupting biological processes such as cytochrome oxidase function. These results highlight the potential risks of MPs in marine ecosystems and underscore the need for further research to understand their long-term effects. Full article

Video temporal grounding (VTG) aims to localize a semantically relevant temporal segment within an untrimmed video based on a natural language query. The task continues to face challenges arising from cross-modal semantic misalignment, which is largely attributed to redundant visual content in sensor-acquired video streams, linguistic ambiguity, and discrepancies in modality-specific representations. Most existing approaches rely on intra-modal feature modeling, processing video and text independently throughout the representation learning stage. However, this isolation undermines semantic alignment by neglecting the potential of cross-modal interactions. In practice, a natural language query typically corresponds to spatiotemporal content in video signals collected through camera-based sensing systems, encompassing a particular sequence of frames and its associated salient subregions. We propose a text-guided visual representation optimization framework tailored to enhance semantic interpretation over video signals captured by visual sensors. This framework leverages textual information to focus on spatiotemporal video content, thereby narrowing the cross-modal gap. Built upon the unified cross-modal embedding space provided by CLIP, our model leverages video data from sensing devices to structure representations and introduces two dedicated modules to semantically refine visual representations across spatial and temporal dimensions. First, we design a Spatial Visual Representation Optimization (SVRO) module to learn spatial information within intra-frames. It selects salient patches related to the text, capturing more fine-grained visual details. Second, we introduce a Temporal Visual Representation Optimization (TVRO) module to learn temporal relations from inter-frames. Temporal triplet loss is employed in TVRO to enhance attention on text-relevant frames and capture clip semantics. Additionally, a self-supervised contrastive loss is introduced at the clip–text level to improve inter-clip discrimination by maximizing semantic variance during training. Experiments on Charades-STA, ActivityNet Captions, and TACoS, widely used benchmark datasets, demonstrate that our method outperforms state-of-the-art methods across multiple metrics. Full article

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure has long been associated with reproductive dysfunction in males and females even at miniscule levels, which can persist across generations. Given the continued industrial use and detection of other aryl hydrocarbon receptor (AhR) agonists in the general population and the demonstrated heritable phenotypes of TCDD exposure, further work is justified to elucidate reproductive pathologies and minimize exposure risk. In females, multi- and transgenerational subfertility has been demonstrated in a zebrafish (Danio rerio) model exposed to 50 pg/mL TCDD once at 3 and 7 weeks post fertilization (wpf). We further characterize the histopathologic, hormonal and transcriptomic outcomes of the mature female zebrafish ovary following early-life TCDD exposure. Exposure was associated with significantly increased ovarian atresia in the F0 and F1, but not F2 generation. Other oocyte staging and vitellogenesis were unaffected in all generations. Exposed F0 females showed increased levels of whole-body triiodothyronine (T3) and 17β-estradiol (E2) levels, but not vitellogenin (Vtg), 11-ketotestosterone (11-KT), cortisol, thyroxine (T4), or testosterone (T). Ovarian transcriptomics were most dysregulated in the F2. Both F0 and F2, but not F1, showed changes in epigenetic-related gene expression. Rho signaling was the top pathway for both F0 and F2. Full article

Estrogen plays some important roles in many physiological processes in animals. This hormone is used as a type of medication for humans and animals, including fish, but is associated with serious side effects and environmental persistence, which has led to a growing interest in phytoestrogens as an alternative. Phytoestrogens are compounds derived from plants that are structurally similar to estrogen and may exhibit similar behavior in the body. To date, no studies have investigated the activity of phytoestrogens in relation to the maturation of eels. In the present study, we investigated the effects of ten different plant extracts on vitellogenin (vtg) and estrogen receptor (esr1, esr2) gene expression in eel hepatocytes. As a result, Schisandra and Astragalus extracts induced higher levels of vtg mRNA expression compared to the other extracts. However, increased esr mRNA expression was observed only in the Schisandra and soybean extract-treated groups. The phytoestrogens known to be present in Schisandra and Astragalus were analyzed using HPLC. Schizandrin, gomisin A, and gomisin N were detected in Schisandra extract, and calycosin and formononetin were detected in Astragalus extract. We then examined whether these phytoestrogens could induce vtg mRNA expression in eel hepatocytes. As a result, gomisin N and formononetin significantly induced vtg mRNA expression. In conclusion, among the 10 plant extracts treated in this study, Schisandra and Astragalus extracts induced estrogenic activity in eel hepatocytes. These extracts were found to contain phytoestrogens, with gomisin N and formononetin identified as the primary active components responsible for the observed estrogenic activity in eel hepatocytes. Full article

Global consumption led to increased and persistent plastic pollution in aquatic environments, affecting aquatic biota. Polystyrene (PS) is a synthetic polymer and one of the most widely used plastics. This study aims to investigate the acute and chronic effects of PS microplastics on Cyprinus carpio using an adapted OECD methodology. For the acute test, PS was tested in different particle sizes (20, 200, and 430 µm), each at concentrations of 0, 1, 10, and 100 mg PS/L. Mortality and clinical signs were monitored after 96 h of exposure. No acute effects were recorded. In the chronic test, a mix of PS particles of different sizes (20, 200, and 430 µm) at a total concentration of 1.2 mg PS/L was used for a 75-day fish exposure. Mortality, biometric parameters, physiological indices, and antioxidant enzyme activities, including catalase (CAT), glutathione reductase (GRed), glutathione S-transferase (GST), 7-ethoxyresorufin-O-deethylase (EROD), lipid peroxidation (MDA), hepatic enzymes (alanine aminotransferase—ALT and aspartate aminotransferase—AST), vitellogenin (VTG), and acetylcholinesterase (ACh), were assessed. Fish exposed to the PS mix exhibited a 40% change in hepatosomatic indices after 75 days. Additionally, the PS mix induced oxidative stress in fish organs. CAT activity increased fourfold in the intestine, GRed activity increased thirtyfold in the gonads, and GST activity doubled in the brain. GRed activity also increased in the gills but was not statistically significant compared to the control. Lipid peroxidation was observed in the kidney (twofold increase) and was also detected in the gills and intestine; however, these changes were not statistically significant. EROD activity increased by 15% compared to the control group, indicating an amplification of stress enzyme expression. The activity of hepatic enzymes ALT and AST increased nine to tenfold compared to the control. VTG activity increased by 47%, and ACh activity showed more than 80% inhibition in the brain and muscle. Furthermore, an overall amplification of protein expression in the intestine and liver was observed compared to the control group. Our study revealed the incidence and severity of PS microplastic effects on freshwater fish and emphasized the urgent need for prevention, monitoring, and mitigation measures to combat microplastic pollution. Full article

Photoperiod regulates reproductive physiology in many fishes, but its sex-specific molecular effects under artificial manipulation remain unclear, especially in cold-water species. In this study, we investigated whether photoperiod manipulation during the reproductive season could modulate the rate and efficiency of gonadal development in the Amur minnow (Phoxinus lagowskii). High-throughput RNA sequencing was used to analyze transcriptomic responses of gonadal tissues under three photoperiod regimes: natural light (12L:12D), continuous light (24L:0D), and continuous darkness (0L:24D) over a 9-week experimental period. Our results revealed distinct sex-specific gonadal responses to photoperiodic changes. In males, continuous light significantly promoted spermatogenesis by upregulating meiosis-related genes (REC114 and syp3) and steroid biosynthesis. In females, prolonged light exposure induced ovarian stress, evidenced by vitellogenin (Vtg3) upregulation and retinoic acid suppression, whereas continuous darkness promoted lipid storage via downregulation of gluconeogenesis (PC and Fbp2) and fatty acid oxidation (ACSL1a). Additionally, immune activation, marked by IL1RAPL1-A upregulation, was observed in all groups except continuous-light males, with females exhibiting broader immune pathway engagement. These findings provide novel insights into the regulatory mechanisms of photoperiod-induced gonadal development and highlight potential strategies for optimising photoperiod management in cold-water fish aquaculture. Full article

The great white shark (Carcharodon carcharias), a keystone predator vital to marine ecosystem stability, is increasingly exposed to anthropogenic threats, including endocrine-disrupting chemicals (EDCs). This study highlights the use of non-invasive epidermal biopsies to assess physiological and ecological parameters in 28 live specimens sampled from the Dyer Island Nature Reserve, South Africa. Epidermal tissue was analyzed for vitellogenin (Vtg), a biomarker of estrogenic exposure, while dermal tissue was used for stable isotope analyses of carbon and nitrogen, essential for understanding the feeding habitat of white sharks. Vitellogenin, typically restricted to sexually mature females, was unexpectedly detected in males and immature females, indicating significant exposure to estrogenic pollutants. This finding raises concerns about the potential reproductive and population-level impacts on this vulnerable species. Stable isotope analyses confirmed that dermal tissue alone is sufficient for trophic studies, eliminating the need for deeper muscle sampling. By demonstrating that epidermal and dermal tissues provide critical data for both biomarkers and isotopic studies, this research supports the adoption of minimally invasive techniques. Shallower biopsies reduce stress on the animals, making this method a valuable tool for conservation research and management of C. carcharias. Full article

Valine-glutamine (VQ) motif-containing proteins play important roles in diverse plant developmental processes and signal transduction in response to biotic and abiotic stresses. However, no systematic investigation has been conducted on VQ genes in watermelon. In this study, we identified 31 watermelon VQ genes, which were classified into six subfamilies (I–VI). All of the deduced proteins contained a conserved FxxxVQxL/F/VTG motif. Eleven ClVQs were involved in segment duplication, which was the main factor in the expansion of the VQ family in watermelon. Numerous stress- and hormone-responsive cis-elements were detected in the putative promoter region of the ClVQ genes. Green fluorescent protein fusion proteins for ten selected ClVQs were localized in the nucleus, but three ClVQs also showed signals in cell membranes and the cell wall, thus confirming their predicted divergent functionality. Quantitative real-time PCR (qRT-PCR) analysis indicated that the majority of ClVQ genes were specifically or preferentially expressed in certain tissues or organs, especially in the male flower. Analyses of RNA-sequencing data under osmotic, cold, and drought stresses and Cucumber green mottle mosaic virus (CGMMV) infection revealed that the majority of ClVQ genes, especially those from subfamily IV, were responsive to these stresses. The results provide useful information for the functional characterization of watermelon ClVQ genes to unravel their biological roles. Full article

Vitellogenins (Vtgs) are key yolk precursor proteins in fish, serving as critical indicators of gonadal maturation in females and reliable biomarkers for detecting xeno-oestrogenic pollution, particularly through their expression in juveniles or males. The vtg gene family comprises multiple subtypes that are species-specific, necessitating precise characterisation and quantification for effective use as biomarkers in studies on estrogenic endocrine-disrupting chemicals (EEDCs). In this study, we successfully cloned and characterised the full-length cDNAs of three vtg subtypes (vtgAa, vtgAb, and vtgC) from Scatophagus argus. Differential expression analysis revealed that vtgAb exhibited the highest responsiveness to 17α-ethynylestradiol (EE2) exposure, with a 3-fold increase in vivo at 10.0 μg/g EE2 and a 30-fold increase in vitro at 10⁻⁷ mol/L EE2. The expression patterns were dose- and time-dependent, with peak expression observed 72 h post-exposure. While in vivo assays indicated moderate upregulation, in vitro experiments demonstrated significantly higher expression, attributed to direct hepatocyte interaction with EE2. These findings confirm vtgAb as the most responsive subtype to oestrogen exposure in S. argus and highlight the species’ tolerance to EE2, as compared to more sensitive species like Danio rerio. This study shows the evolutionary conservation of vtg transcripts across teleost species and reinforces the importance of subtype-specific characterisation to advance their application as biomarkers for EEDCs, with significant implications for environmental monitoring and pollution regulation. Full article

Antarctic krill oil has been proven to be able to promote the ovarian development of crustaceans, but its optimal application dose and potential regulatory mechanism in Macrobrachium rosenbergii are still unclear. In this study, five isonitrogenous and isolipidic diets with gradient additions of Antarctic krill oil (0%, 1.5%, 3%, 4.5%, and 6%) were served exposed to 8 weeks of feeding. The results show that 3–4.5% Antarctic krill oil supplementation significantly increases the weight gain rate and specific growth rate of M. rosenbergii (p < 0.05). In addition, 3–4.5% Antarctic krill oil supplementation significantly increased the content of hemolymph vitellogenin (VTG) and the levels of reproductive hormones, including methyl farnesoate (MF), estradiol (E₂), and progesterone (P₄) (p < 0.05). The differences in ovarian index, oocyte volume, yolk granule deposition in oocytes, and the transcription levels of VTG genes in hepatopancreas and ovarian tissues demonstrated that the addition of Antarctic krill oil significantly promoted ovarian development and vitellogenesis, especially at the 4.5% addition level. In terms of molecular signaling, this study confirms that the retinol metabolic signaling pathway, MF signaling pathway, steroid hormone signaling pathway, and ecdysone signaling pathway, along with their specific molecules, such as Farnesoic acid-O-methyltransferase (FAMeT), retinoid x receptor (RXR), ecdysone receptor (EcR), and estrogen-related receptor (ERR), are involved in the regulation of the ovarian development of M. rosenbergii by adding Antarctic krill oil at appropriate doses. The findings indicate that the supplementation of 4.5% Antarctic krill oil in the diet is optimal for stimulating the secretion of reproductive hormones in female M. rosenbergii, thereby promoting vitellogenesis and ovarian development. Full article