Environmentally responsive changes in mucus indicators and microbiota of Chinese sturgeon Acipensersinensis.

The impact of environmental factors on the health of the endangered Chinese sturgeon (Acipenser sinensis) and the potential hazards associated with sample collection for health monitoring pose urgent need to its conservation. In this study, Chinese sturgeons were selected from indoor and outdoor environments to evaluate metabolic and tissue damage indicators, along with a non-specific immune enzyme in fish mucus. Additionally, the microbiota of both water bodies and fish mucus were determined using 16S rRNA high-throughput sequencing. The correlation between the indicators and the microbiota was investigated, along with the measurement of multiple environmental factors. The results revealed significantly higher levels of two metabolic indicators, total protein (TP) and cortisol (COR) in indoor fish mucus compared to outdoor fish mucus (p < 0.05). The activities of acid phosphatase (ACP), alkaline phosphatase (ALP), creatine kinase (CK), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were significantly higher in indoor fish, serving as indicators of tissue damage (p < 0.05). The activity of lysozyme (LZM) was significantly lower in indoor fish (p < 0.01). Biomarker analysis at the phylum and genus levels in outdoor samples revealed that microorganisms were primarily related to the catabolism of organic nutrients. In indoor environments, microorganisms displayed a broader spectrum of functions, including ecological niche establishment, host colonization, potential pathogenicity, and antagonism of pathogens. KEGG functional enrichment corroborated these findings. Dissolved oxygen (DO), electrical conductivity (EC), ammonia nitrogen (NH3-N), turbidity (TU), and chemical oxygen demand (COD) exerted effects on outdoor microbiota. Temperature (TEMP), nitrate (NO3-), total phosphorus (TP), and total nitrogen (TN) influenced indoor microbiota. Changes in mucus indicators, microbial structure, and function in both environments were highly correlated with these factors. Our study provides novel insights into the health impacts of different environments on Chinese sturgeon using a non-invasive method.

Effects of Citrobacter freundii on sturgeon: Insights from skin mucosal immunology and microbiota.

Skin mucus analysis has recently been used as a non-invasive method to evaluate for fish welfare. The present research study was conducted to examine the skin mucosal immunity and skin microbiota profiles of sturgeons infected with Citrobacter freundii. Our histology results showed that the thickness of the epidermal layer of skin remained thinner, and the number of mucous cells was significantly decreased in sturgeons after infection (p < 0.05). Total protein, alanine aminotransferase, aspartate aminotransferase, superoxide dismutase, and creatine kinase levels in the mucus showed biphasic pattern (decrease and then increase). Lactate dehydrogenase, lysozyme, and acid phosphatase activities in the mucus showed an increasing trend after infection. Furthermore, 16S rRNA sequencing also revealed that C. freundii infection also affected the diversity and community structure of the skin mucus microbiota. An increase in microbial diversity (p > 0.05) and a decrease in microbial abundance (p < 0.05) after infection were noted. The predominant bacterial phyla in the skin mucus were Proteobacteria, Fusobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Specifically, the relative abundance of Fusobacteria increased after infection. The predominant bacterial genera in the skin mucus were Cetobacterium, Pelomonas, Bradyrhizobium, Flavobacterium, and Pseudomonas. The relative abundance of Cetobacterium, Pseudomonas, and Flavobacterium increased after infection. Our current research findings will provide new insights into the theoretical basis for future research studies exploring the mechanism of sturgeon infection with C. freundii.

Pharmaceutical Residues in Edible Oysters along the Coasts of the East and South China Seas and Associated Health Risks to Humans and Wildlife.

The investigation of pharmaceuticals as emerging contaminants in marine biota has been insufficient. In this study, we examined the presence of 51 pharmaceuticals in edible oysters along the coasts of the East and South China Seas. Only nine pharmaceuticals were detected. The mean concentrations of all measured pharmaceuticals in oysters per site ranged from 0.804 to 15.1 ng g-1 of dry weight, with antihistamines being the most common. Brompheniramine and promethazine were identified in biota samples for the first time. Although no significant health risks to humans were identified through consumption of oysters, 100-1000 times higher health risks were observed for wildlife like water birds, seasnails, and starfishes. Specifically, sea snails that primarily feed on oysters were found to be at risk of exposure to ciprofloxacin, brompheniramine, and promethazine. These high risks could be attributed to the monotonous diet habits and relatively limited food sources of these organisms. Furthermore, taking chirality into consideration, chlorpheniramine in the oysters was enriched by the S-enantiomer, with a relative potency 1.1-1.3 times higher when chlorpheniramine was considered as a racemate. Overall, this study highlights the prevalence of antihistamines in seafood and underscores the importance of studying enantioselectivities of pharmaceuticals in health risk assessments.

Indexing serum and mucous biochemical parameters of endangered Chinese sturgeon Acipenser sinensis with implications for health assessment.

The Chinese sturgeon (Acipenser sinensis) is a critically endangered aquatic fish. Health monitoring and welfare assessments are critical for the conservation of Chinese sturgeon. In this study, biochemical parameters of serum and skin mucus in Chinese sturgeon were examined to evaluate the potential biomarkers. Serum and mucous samples were obtained from Chinese sturgeon, and the levels of total protein (TP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatine kinase (CK), lactic acid (LD), acid phosphatase (ACP), lysozyme (LYZ), glucose (GLU), and cortisol were determined. The concentrations of ALT, AST, cortisol, and LYZ were significantly higher in the mucous group than those in the serum group (p < 0.05). In addition, the concentrations of ALP, ACP, LD, LDH, CK, and TP were significantly higher level in the serum group than those in the mucous group (p < 0.05). Moreover, the correlations between serum and mucous biochemical parameters were established. Statistical analysis showed a positive correlation between serum and skin mucous markers (ACP, cortisol, and LYZ). AST versus ALT in serum and mucus showed a significant positive correlation (p < 0.01). A significant positive correlation was found between cortisol and CK in mucus (p < 0.01). Moreover, LD versus LDH in serum showed a significant but weak positive correlation (p < 0.01). Principal component analysis revealed a complete separation between the serum and mucous groups, with the biomarkers that contributed the most being ALP, TP, ALT, and AST. This study provides baseline data and reference intervals for serum and mucous biochemical parameters in presumably healthy Chinese sturgeons. The current study has important implications for the development of conservation strategies and the conservation status of critically endangered species.

Enhancing immune and antioxidant responses in Nile tilapia through dietary supplementation with Ulva fasciata extract: A study on gene expression and resistance to Aeromonas hydrophila.

BACKGROUND: The study focused on the impact of Ulva fasciata extract (UFE) supplementation in the diets of Nile tilapia (Oreochromis niloticus) on blood and biochemical markers, immune and oxidative responses, and the expression of related genes, with a specific interest in their condition following exposure to Aeromonas hydrophila. METHODS: Four different levels of UFE were tested in the diets: 0% (0 mg kg- 1) for the control group (U0), and incremental additions of 0.05% (50 mg kg-1), 0.1% (100 mg kg-1), and 0.15% (150 mg kg-1) for the experimental groups U50, U100, and U150 respectively. Groups of 45 fish weighing 3.126 ± 0.120 g were fed these diets over 90 days. RESULTS: The study found that groups treated with UFE showed statistically significant enhancements (p < 0.05) compared to the control group. These improvements included increased red and white blood cell counts, higher haemoglobin concentrations, greater packed cell volume, and elevated enzyme activities-specifically, superoxide dismutase, catalase, alanine aminotransferase, and aspartate aminotransferase. Additionally, lysozyme and phagocytic activities were notably higher, especially in the U100 group after exposure. Before exposure to Aeromonas hydrophila, all levels of UFE supplementation led to increased expression of TNF-α and COXII genes and decreased NFκ-B expression. After the challenge, UFE intake resulted in varied expression levels of immune and antioxidant genes (TNF-α, NFκ-B, SOD, and COXII) in the liver, with the most effective responses observed in the U50, U100, and U150 groups. CONCLUSIONS: The findings underscore the potential of dietary UFE as a natural antioxidant and immune booster for Nile tilapia.

Effects of phytase enzyme supplementation on growth performance, intestinal morphology and metabolism in Nile tilapia (Oreochromis niloticus).

Phytase is crucial in enhancing the bioavailability and release of phosphorus and other nutrients bound to phytic acid, making them more bioavailable for animal absorption. This study was carried out to inspect the effect of supplementing low phosphorus (P) diet with di-calcium phosphate (DCP) and liquid phytase enzyme (LP), which contains 1500 FTU/kg, on growth performance, intestinal morphometry, proximate body chemical composition, blood profile, immunity status, liver mitochondrial enzyme activities, the expression response and economic returns of Nile tilapia (Oreochromis niloticus). Three triplicate groups of fish (initial weight 5.405 ± 0.045 g, N = 90) were fed on three different diets for 90 days. The first was a control diet with zero DCP; the second was a control diet supplemented with 0.71% DCP; the third was a control diet supplemented with 0.03% LP. The groups were designated as CG, DCP and LP, respectively. Results showed that LP induced considerable improvements (p < 0.05) in FBW, body weight gain, weight gain rate, specific growth rate, HIS, viscero-somatic index, spleen-somatic index, feed conversion ratio, blood parameters and the histomorphometry assessment of intestinal villi absorptive capacity, compared with the other groups. Also, whole-body protein and lipid contents pointedly (p < 0.05) increased by LP, compared with the DCP group. A positive response (p < 0.05) to the phytase enzyme was noted in complexes I, III and IV of the mitochondrial liver complex enzyme activity. Likewise, the relative gene expression levels of (GHr-1, IGF-1, FAS and LPL) were notably (p < 0.05) upregulated by phytase enzyme, associated with DCP and control groups. Further, phytase recorded the highest total return and profit percentage. It can be concluded that Nile tilapia benefits from using phytase enzyme 1500 FTU/kg at 0.03% without adding DCP in terms of good performance and profits.

Predator Presence Alters Intestinal Microbiota in Mussel.

Intestinal microbes are essential participants in host vital activities. The composition of the microbiota is closely related to the environmental factors. Predator presence may impact on intestinal microbiota of prey. In the present study, stone crab Charybdis japonica was used as potential predator, an external stress on mussel Mytilus coruscus, to investigate the intestinal microbiota alteration in M. coruscus. We set up two forms of predator presence including free crab and trapped crab, with a blank treatment without crab. The composition of intestinal microbiota in mussels among different treatments showed significant differences by 16S rRNA techniques. The biodiversity increased with trapped crab presence, but decreased with free crab presence. Neisseria, the most abundant genus, fell with the presence of crabs. Besides, the Arcobacter, a kind of pathogenic bacteria, increased with free crab presence. Regarding PICRUTs analysis, Environmental Information Processing, Genetic Information Processing and Metabolism showed differences in crab presence treatments compared with the blank, with a bit higher in the presence of free crab than trapped crab. In conclusion, trapped crab effects activated the metabolism and immunity of the intestinal flora, but free crabs made mussels more susceptible to disease and mortality, corresponding to the decreased biodiversity and the increased Arcobacter in their intestine.

Effects of Ocean Acidification and Microplastics on Microflora Community Composition in the Digestive Tract of the Thick Shell Mussel Mytilus coruscus Through 16S RNA Gene Sequencing.

Ocean acidification and microplastic pollution is a global environmental threat, this research evaluated the effects of ocean acidification and microplastics on mussel digestive tract microbial community. The 16S rRNA gene was sequenced to characterize the flora. Species diversity in the samples was assessed by clustering valid tags on 97% similarity. Bacteroidetes, Firmicutes and Proteobacteria were the three most abundant genera in the four groups, with Bacteroidetes showing the highest diversity. However, no differences in flora structure were evident under various treatments. Phylogenetic relationship analysis revealed Bacteroidetes and Firmicutes had the highest OTU diversity. The weighted UniFrac distance, principal coordinate analysis (PCoA), unweighted pair group method with arithmetic mean (UPGMA) cluster tree and analysis of molecular variance (AMOVA) evaluation results for all samples also showed that changes in pH and microplastics concentration did not significantly affect the microbial community structure in the mussel digestive tract. The results presented the no significant effects of ocean acidification and microplastics intake on mussel intestinal diversity.

Toxic effects of nano-TiO2 in bivalves-A synthesis of meta-analysis and bibliometric analysis.

Since the beginning of the 21st century, the increasing production and application of nano-TiO2 in consumer products have inevitably led to its release into aquatic systems and therefore caused the exposure of aquatic organisms, resulting in growing environmental concerns. However, the safety of nano-TiO2 in aquatic environments has not been systematically assessed, especially in coastal and estuary waters where a large number of filter-feeding animals live. Bivalves are considered around the world to be a unique target group for nanoparticle toxicity, and numerous studies have been conducted to test the toxic effects of nano-TiO2 on bivalves. The aim of this review was to systematically summarize and analyze published data concerning the toxicological effects of nano-TiO2 in bivalves. In particular, the toxicity of nano-TiO2 to the antioxidant system and cell physiology was subjected to meta-analysis to reveal the mechanism of the toxicological effects of nano-TiO2 and the factors affecting its toxicological effects. To reveal the cooperation, hot keywords and co-citations in this field, bibliometric analysis was conducted, and the results showed that the toxicological molecular mechanisms of nano-TiO2 and the combined effects of nano-TiO2 and other environmental factors are two major hot spots. Finally, some perspectives and insights were provided in this review for future research on nano-TiO2 toxicology in bivalves.

Rethinking Nano-TiO2 Safety: Overview of Toxic Effects in Humans and Aquatic Animals.

Titanium dioxide nanoparticles (nano-TiO2 ) are widely used in consumer products, raising environmental and health concerns. An overview of the toxic effects of nano-TiO2 on human and environmental health is provided. A meta-analysis is conducted to analyze the toxicity of nano-TiO2 to the liver, circulatory system, and DNA in humans. To assess the environmental impacts of nano-TiO2 , aquatic environments that receive high nano-TiO2 inputs are focused on, and the toxicity of nano-TiO2 to aquatic organisms is discussed with regard to the present and predicted environmental concentrations. Genotoxicity, damage to membranes, inflammation and oxidative stress emerge as the main mechanisms of nano-TiO2 toxicity. Furthermore, nano-TiO2 can bind with free radicals and signal molecules, and interfere with the biochemical reactions on plasmalemma. At the higher organizational level, nano-TiO2 toxicity is manifested as the negative effects on fitness-related organismal traits including feeding, reproduction and immunity in aquatic organisms. Bibliometric analysis reveals two major research hot spots including the molecular mechanisms of toxicity of nano-TiO2 and the combined effects of nano-TiO2 and other environmental factors such as light and pH. The possible measures to reduce the harmful effects of nano-TiO2 on humans and non-target organisms has emerged as an underexplored topic requiring further investigation.

Impact of Initial Feeding and Molting on Tachypleus tridentatus Gut Microbiota.

Tri-spine horseshoe crabs (HSCs) Tachypleus tridentatus have been facing the threat of population depletion for decades, and the physiology and microbiology of their early life stages are lacking. To explore what directs the change of juvenile T. tridentatus gut microbiota and how gut microbiota change, by using 16S rRNA sequencing of gut samples we detected the intestinal microbiome of juvenile HSCs and compared the impact of initial molting and initial feeding, as well as the effect of environment. Results showed that the predominant phyla in the gut microbial community of juvenile HSCs are Proteobacteria and Bacteroidetes. The richness and diversity of intestinal microbes greatly decreased after initial molting. Microbial-mediated functions predicted by PICRUSt showed that "Signal Transduction", "Cellular Processes and Signaling", "Infective Diseases" and "Digestive System" pathways significantly increased in 2nd instars. As for the effect of environment, the connection between living environment and the intestinal microbiome started to manifest after initial molting. Unexpectedly, initial feeding treatment slightly affected the intestinal microbiome of T. tridentatus in the early life stage, whereas the effect of initial molting was significant. The present study provided the first insight into the gut microbiota of T. tridentatus, and the findings led a new sight to explain what guide the change of gut microbiota.

Modulatory effect of glutamate GluR2 receptor on the caudal neurosecretory Dahlgren cells of the olive flounder, Paralichthys olivaceus.

A neuromodulatory role for glutamate has been reported for magnocellular neuroendocrine cells in mammalian hypothalamus. We examined the potential role of glutamate as a local intercellular messenger in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) in the euryhaline flounder Paralichthys olivaceus. In pharmacological experiments in vitro, glutamate (Glu) caused an increase in electrical activity of Dahlgren cells, recruitment of previously silent cells, together with a greater proportion of cells showing phasic (irregular) activity. The glutamate substrate, glutamine (Gln), led to increased firing frequency, cell recruitment and enhanced bursting activity. The glutamate effect was not blocked by the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801, or the GluR1/GluR3 (AMPA) receptor antagonist IEm1795-2HBr, but was blocked by the broad-spectrum α-amino-3-hydroxy- 5- methyl-4-isoxazo-lepropionic acid (AMPA) receptor antagonist ZK200775. Our transcriptome sequencing study revealed three AMPA receptor (GluR1, GluR2 and GluR3) in the olive flounder CNSS. Quantitative RT-PCR revealed that GluR2 receptor mRNA expression was significant increased following dose-dependent superfusion with glutamate in the CNSS. GluR1 and GluR3 receptor mRNA expression were decreased following superfusion with glutamate. L-type Ca2+ channel mRNA expression had a significant dose-dependent decrease following superfusion with glutamate, compared to the control. In the salinity challenge experiment, acute transfer from SW to FW, GluR2 receptor mRNA expression was significantly higher than the control at 2 h. These findings suggest that GluR2 is one of the mechanisms which can medicate glutamate action within the CNSS, enhancing electrical activity and hence secretory output.

Dynamic responses of prolactin, growth hormone and their receptors to hyposmotic acclimation in the olive flounder Paralichthys olivaceus.

Prolactin (PRL) and growth hormone (GH) play important roles in regulating salt and water balance through osmoregulatory organs in vertebrates. The aim of this study was to investigate the dynamic changes of GH/PRL hormone gene expressions in the pituitary gland and their receptors in gill and kidney, as well as the plasma osmolality when the olive flounder fish Paralichthys olivaceus were acclimated in freshwater (FW) conditions. After transfer from seawater (SW) to freshwater (FW), the osmolality of FW-adaption fish reached the lowest level at 1d which rose slightly afterwards. However, the hormone gene expression of PRL increased from 2d, reaching its peak at 5d, and then decreased at 14d. At this time, the value was still significantly higher than the control, showing a similar trend to the plasma hormone PRL. In contrast, the pituitary mRNA level of GH significantly decreased at 1d and then returned to normal levels. The mRNA levels of PRL receptor (PRLR) in both gill and kidney displayed a similar trend to the pituitary PRL. We also observed the synchronous expression trend of the renal PRLR with pituitary PRL (5d) and the asynchronous expression peaks between branchial (8d) and renal PRLR (5d). Significant responses of GH and its receptor (GHR) in both gill and kidney during the FW-acclimation were not observed. Nevertheless, the gene expression of GH receptor variant (GHR-V) in both gill and kidney declined at 2d, indicating unknown osmoregulatory functions of GHR-V. Collectively, our results provided more insights of the PRL, GH and their corresponding receptors in modulating osmoregulatory responses, representing an important aspect of FW-acclimation in flounder fish.

Antioxidant response of the hard shelled mussel Mytilus coruscus exposed to reduced pH and oxygen concentration.

Ocean acidification (OA) and hypoxic events are increasing worldwide problems, their interactive effects have not been well clarified, although their co-occurrence is prevalent. The East China Sea (the Yangtze River estuary area) suffers from not only coastal hypoxia but also pH fluctuation, representing an ideal study site to explore the combined effect of OA and hypoxia on marine bivalves. We experimentally evaluated the antioxidant response of the mussel Mytilus coruscus exposed to three pH levels (8.1, 7.7 and 7.3) at two dissolved oxygen (DO) levels (2.0mgL-1 and 6.0mgL-1) for 72h. Activities of superoxide dismutase, catalase, glutathione peroxidase, acid phosphatase, and alkaline phosphatase and levels of malondialdehyde were measured in gills and hemolymph. All enzymatic activities in hemolymph and gills followed a similar pattern throughout the experiment duration. Generally, low DO showed greater effects on enzyme activities than elevated CO2. Significant interactions between DO, pH and time were only observed at superoxide dismutase and catalase in both tissues. PCA revealed positive relationships between most enzyme activities in both gills and hemolymph with the exception of alkaline phosphatase activity and the level of malondialdehyde in the hemolymph. Overall, our results suggested that decreased pH and low DO induced similar antioxidant responses in the hard shelled mussel, and showed an additive effect on most enzyme activities. The evaluation of multiple environmental stressors, a more realistic scenario than single ones, is crucial to predict the effect of future global changes on coastal species and our results supply some insights on the potential combined effects of reduced pH and DO on marine bivalves.

Combined effects of seawater acidification and high temperature on hemocyte parameters in the thick shell mussel Mytilus coruscus.

In this work, flow cytometry was used to examine the immune responses of hemocytes in the thick shell mussel Mytilus coruscus exposed to six combinations of pH (7.3, 7.7, and 8.1) and temperature (25 °C and 30 °C) for 14 days. Temperature showed significant effects on all immune parameters throughout the experiment. Generally, the total hemocyte count (THC), phagocytosis (Pha), esterase (Est), and lysosomal content (Lyso) significantly decreased at high temperature. By contrast, the hemocyte mortality (Hm) and reactive oxygen species (ROS) levels increased at high temperature. Moreover, pH significantly influenced all the immune parameters, but its effects are not as strong as those of temperature; only Hm, Est, and THC were negatively affected by pH throughout the experiment. After 7 days, low pH resulted in decreased Lyso and increased Hm and ROS levels. Significant interactions between temperature and pH in most measured parameters from 7 days suggested that long-term combined stress, i.e., low pH and high temperature, would cause more severe effects on mussel health than an individual stressor in the field.

Effect of pH and temperature on antioxidant responses of the thick shell mussel Mytilus coruscus.

This study evaluated the combined effects of seawater pH decrease and temperature increase on the activity of antioxidant enzymes in the thick shell mussel Mytilus coruscus, an ecological and economic bivalve species widely distributed along the East China Sea. Mussels were exposed to three pH levels (8.1, 7.7 and 7.3) and two temperatures (25 °C and 30 °C) for 14 days. Activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione (GSH), acid phosphatase (ACP), alkaline phosphatase (AKP) and glutamic-pyruvic transaminase (GPT) were measured in gills and digestive glands after 1, 3, 7 and 14 days of exposure. All enzymatic activities were significantly impacted by pH, temperature. Enzymatic activities at the high temperature were significantly higher than those at the low temperature, and the mussels exposed to pH 7.3 showed significantly higher activities than those under higher pH condition for all enzymes except ACP. There was no interaction between temperature and pH in two third of the measured activities suggesting similar mode of action for both drivers. Interaction was only consistently significant for GPX. PCA revealed positive relationships between the measured biochemical indicators in both gills and digestive glands. Overall, our results suggest that decreased pH and increased temperature induce a similar anti-oxidative response in the thick shell mussel.

The effects of bivalve aquaculture on carbon storage in the water column and sediment of aquaculture areas.

Many researchers have evaluated the fishery carbon sink potential of bivalve aquaculture, with most studies focusing on the Life Cycle Assessment (LCA) of individual bivalves, and there is currently no consensus on whether bivalves are carbon sinks or carbon sources. It is worth noting that most studies have not considered the impact of bivalve aquaculture on ecosystems when evaluating its carbon sink potential. In this context, based on existing literature, this article aims to comprehensively review the effects of bivalve aquaculture on carbon storage in the water column and sediment of aquaculture areas. In general, our findings revealed that moderate and low stocking densities of bivalve aquaculture do not lead to significant changes in the abundance of phytoplankton, but it does indeed alter the phytoplankton community structure from dominated by huge diatom with lower carbon densities to dominated by small phytoplankton with higher carbon densities. Therefore, bivalve aquaculture may increase the total carbon storage in the water column. In addition, bivalve aquaculture also increases the sedimentation rate of suspended particles, increasing the rate of carbon burial, especially in low-energy environment and shallow water areas. The findings of this article fill the knowledge gap of fishery carbon sink in bivalve aquaculture from an ecosystem perspective.

Nano titanium dioxide alleviates the toxic effects of tris (2-chloropropyl) phosphate on the digestive gland and hemolymph of thick-shell mussel Mytilus coruscus.

In the marine environment, nanoparticles play a role in adsorbing and catalytically degrading organic pollutants, thereby mitigating their toxic effects on aquatic organisms. This study aimed to investigate the impact of nano titanium dioxide (nTiO2) and tris (2-chloropropyl) phosphate (TCPP) on the hemolymph and digestive function of the thick-shell mussel Mytilus coruscus. Mussels were divided into a control group, a group exposed to TCPP alone, a group exposed to a combination of TCPP and 0.5 mg/L nTiO2, and a group exposed to a combination of TCPP and 1 mg/L nTiO2. After 14 days of exposure, oxidative stress responses, including superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, immune defense responses, including acid phosphatase (ACP) and alkaline phosphatase (AKP) activities, and gene expression, including HSP70 expression, were measured in the hemolymph and digestive glands of the mussels. Compared to the control group, mussels solely exposed to 100 µg/L TCPP exhibited a significant reduction in SOD activity in the hemolymph. When TCPP was co-exposed with 0.5 mg/L nTiO2, there were significant increases in MDA content and AKP activity in both the digestive gland and hemolymph compared to the control group. Upon co-exposure of TCPP with 1 mg/L nTiO2, MDA content and AKP activity in the digestive gland significantly decreased, while SOD, ACP, and AKP activity in the hemolymph significantly increased and MDA content significantly decreased, returning to the control group levels. Furthermore, in the combined exposure, HSP70 gene expression significantly decreased as the nTiO2 concentration increased from 0.5 mg/L to 1 mg/L. In summary, TCPP impacted the hemolymph and digestive function of mussels, whereas a concentration of 1 mg/L nTiO2 effectively alleviated the toxic effects of TCPP. This study is crucial for assessing the ecological risks of nanoparticles and emerging organic pollutants in marine environments, and provides new insights into the interaction between nTiO2 and TCPP, as well as the influence of nTiO2 concentration on mitigating TCPP toxicity.

Saving the overlooked mangrove horseshoe crabs-A perspective from enhancing mangrove ecosystem conservation.

Despite being widely distributed in Asia, Carcinoscorpius rotundicauda is often overlooked and, its population status remains unclear. Moreover, it is threatened by illegal harvesting and degradation of mangrove ecosystems. Protecting its habitat is essential for population and biodiversity conservation, as mangroves provide nursery grounds and food supply for C. rotundicauda. This review discusses the biological characteristics of C. rotundicauda, including ecology, nutrition, life history, toxicology, and immunology. It also presents information about its distribution and population status. The review emphasizes the challenges faced by C. rotundicauda and proposes a conservation framework that involves the participation of local residents to facilitate conservation efforts. Collaboration between local residents and communities is proposed to protect and monitor the mangrove ecosystem. Additionally, this framework can support field research, protect C. rotundicauda juveniles and other species, and ensure the livelihood of local residents through participation in carbon trading markets and eco-industries such as eco-farming and eco-tourism.

Combined toxic effects of nanoplastics and norfloxacin on antioxidant and immune genes in mussels.

Nanoplastics (NPs) and antibiotics (ABs) are two of the emerging marine contaminants that have drawn the most attention in recent years. Given the necessity of figuring out the effects of plastic and antibiotic contamination on marine organism life and population in the natural environment, it is essential to apply rapid and effective biological indicators to evaluate their comprehensive toxic effects. In this study, using mussel (Mytilus coruscus) as a model, we investigated the combined toxic effects of NP (80 nm polystyrene beads) and AB (Norfloxacin, NOR) at environmental-relevant concentrations on antioxidant and immune genes. In terms of the antioxidant genes, NPs significantly increased the relative expression of Cytochrome P450 3A-1 (CYP3A-1) under various concentrations of NOR conditions, but they only significantly increased the relative expression of CYP3A-2 in the high concentration (500 µg L-1 NOR) co-exposure group. In the NP-exposure group which exposed to no or low concentrations of NOR, nuclear factor erythroid 2-related factor 2 (Nrf2) was upregulated. In terms of the immune genes, interleukin-1 receptor-associated kinase (IRAK) -1 showed a significant increase in the low-concentration NOR group while a significant inhibition in the high-concentration NOR group. Due to the presence of NPs, exposure to NOR resulted in a significant increase in both IRAK-4 and heat shock protein (HSP) 70. Our findings indicate that polystyrene NPs can exacerbate the effects of NOR on the anti-oxidant and immune defense performance of mussels. This study delves into the toxic effects of NPs and ABs from a molecular perspective. Given the expected increase in environmental pollution due to NPs and ABs, future research is needed to investigate the potential synergistic effect of NPs and ABs on other organisms.