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Microplastics and antibiotic resistance genes are two new pollutants in water environments, and they have potential risks to human health and ecological safety. On the basis of the accumulation of pollutants and microorganisms in sediment, macrobenthic invertebrates are considered as potential practitioners of microplastic degradation and antibiotic resistance gene (ARG) transfer. However, whether microplastic degradation can affect ARG transfer in aquatic environments, especially in the gut of macrobenthic invertebrates, remains unclear. In this study, we demonstrated that microplastics including polyethylene terephthalate (PET), polyvinyl chloride(PVC), polyamide (PA), polystyrene (PS), polypropylene (PP), polyethylene (PE), and polyurethane (PU), and ARGs including tetA, sul1, sul2, and sul3 were widely distributed in sediment and benthic invertebrates in Nansi lake. The distribution of ARGs was related to the number and size of microplastic particles. In particular, it was found for the first time that the content of ARGs corresponding to individual particles was linearly and negatively correlated with the size of microplastics. The results of animal feeding experiments showed that microplastic degradation in the gut of Chironomidae larvae could promote the conjugative transfer of ARGs. The underlying molecular mechanism was SOS response. This study provides a new method for the analysis of the interaction effect of multiple pollutants in freshwater environments. more...

This study explored the effects of water flow on the muscle quality, nutrient composition, and volatile compounds in Cyprinus carpio. Fish were exposed to three treatments: sustained water flow (SG, 1 bl/s, 24 h/d), intermittent water flow (IG, 1 bl/s, 8 h/d), and control group (CG, 3 cm/s). Results indicated that SG improved water-holding capacity, muscle fiber density, hardness, and chewiness, while IG enhanced gumminess, springiness, and resilience. Nutritionally, CG exhibited higher crude lipid content and the highest levels of ΣSFA. Conversely, SG showed elevated ∑EPA + DHA and ω-3 fatty acid levels compared to IG. Volatile compound analysis demonstrated that CG contained higher levels of aldehydes and alcohols, associated with off-flavors, whereas IG and SG produced fresher and sweeter aroma profiles, enhancing sensory quality. These findings provide valuable insights into improving the muscle quality, nutritional value, flavor characteristics, processing, and preservation of common carp through water flow treatment. more...

To reveal the effects of recirculating aquaculture modes on the muscle quality of common carp, the impacts of land-based containers recirculating aquaculture system (C-RAS) and traditional pond system (TP) on the physical properties, nutrient composition, mineral elements, and volatile substances of common carp were analyzed in this experiment. The results showed that dripping, storage, and frozen loss were significantly lower in C-RAS than in TP, while the cooked meat rate was significantly higher than in the TP (P more...

Cylindrospermopsin (CYN), a cyanobacterial toxin, has been detected in the global water environment. However, information concerning the potential environmental risk of CYN is limited, since the majority of previous studies have mainly focused on the adverse health effects of CYN through contaminated drinking water. The present study reported that CYN at environmentally relevant levels (0.1–100 μg/L) can significantly enhance the conjugative transfer of RP4 plasmid in Escherichia coli genera, wherein application of 10 μg/L of CYN led to maximum fold change of ∼6.5- fold at 16 h of exposure. Meanwhile, evaluation of underlying mechanisms revealed that environmental concentration of CYN exposure could increase oxidative stress in the bacterial cells, resulting in ROS overproduction. In turn, this led to an upregulation of antioxidant enzyme-related genes to avoid ROS attack. Further, inhibition of the synthesis of glutathione (GSH) was also detected, which led to the rapid depletion of GSH in cells and thus triggered the SOS response and promoted the conjugative transfer process. Increase in cell membrane permeability, upregulation of expression of genes related to pilus generation, ATP synthesis, and RP4 gene expression were also observed. These results highlight the potential impact on the spread of antimicrobial resistance in water environments. more...

Ribosomal proteins (RPs) not only play an important role in protein synthesis but also have extraribosomal functions. In this study, the entire cDNA sequence of the RPL10a gene of Macrobrachium nipponense (MnRPL10a) was cloned by RACE-PCR. The obtained complete cDNA sequence of the MnRPL10a gene was 885 bp encoding 217 amino acids (AAs). The expression pattern of the MnRPL10a gene was analysed by quantitative real-time fluorescence PCR (qPCR), and its mRNA location was determined by fluorescence in situ hybridization (FISH). The results showed that during development, the highest expression of MnRPL10a in the fertilized ovum. Among tissues, it was mostly expressed in the ovary, and its highest expression was found in stage V ovaries. MnRPL10a mRNA was mainly distributed in the cytoplasm of oogonia and oocytes. The role of the MnRPL10a gene in ovarian development was verified by RNA interference (RNAi) and ovarian explant incubation with 5-hydroxytryptamine (5-HT) and dopamine (DA) experiments. The results indicated that the expression of the genes that positively regulate ovarian development, including vitellogenin (Vg), vitellogenin receptor (Vgr), cell cycle protein B (CyclinB) and cell division cyclin 2 (cdc2), decreased, while the expression of the genes that negatively regulate ovarian development, including Wee1 kinase (Wee1) and OTU domain-containing ubiquitin aldehyde-binding protein B (OTUB), increased with the decrease in MnRPL10a expression after RNAi and DA incubation. However, 5-HT incubation showed the opposite results. In summary, the MnRPL10a gene may regulate the development of the ovary in M. nipponense by affecting vitellin synthesis, oocyte meiosis and the oestrogen signalling pathway. more...

Cyclooxygenase (COX) is the rate-limiting enzyme in the synthesis of prostaglandins (PGs), which are involved in ovarian development and ovulation in crustaceans. In this study, complementary DNA (cDNA) of COX in Macrobrachium nipponense (MnCOX) was identified, and its function in ovarian development and ovulation was investigated by quantitative real-time PCR (qPCR), fluorescence in situ hybridization (FISH), RNA interference (RNAi) and arachidonic acid (AA), dexamethasone (DEX) and DEX+ prostaglandin E2 (PGE2) administration. The results showed that the complete cDNA of MnCOX is 3238 bp, including an 1848 bp open reading frame (ORF) that encodes 615 amino acids. The MnCOX protein conservatively possesses a membrane-binding domain, an epidermal growth factor-like (EGF-like) domain, an animal haem peroxide domain, three N-glycosylation sites and seven essential catalytic residues. The richest MnCOX transcript of nine tissues was found in the gill, followed by the ovary and intestine. In six ovarian development stages, the MnCOX transcript was the richest in the stage Ⅴ ovary. FISH showed that the MnCOX transcript was present in the cytoplasm of oocytes. MnCOX knockdown led to decreases in PGE2 content, expression levels of the vitellogenin (Vg) and vitellogenin receptor (Vgr) genes and the gonadsomatic index (GSI) of prawns. Moreover, oocyte development was delayed, and the oviposition rate and the number of eggs ovulated were reduced after MnCOX knockdown. AA administration increased the expression of MnCOX, PGE2 content and the oviposition rate of prawns. However, DEX administration decreased the expression of MnCOX, PGE2 content, oviposition rate, and the number of eggs ovulated by prawns. The addition of PGE2 to DEX injection rescued the negative effect of DEX on the ovulation of M. nipponense. This investigation illustrates that MnCOX plays an important role in regulating ovarian development and ovulation in M. nipponense by affecting the synthesis of PGs. more...

This study reveals the fluid-structure interaction simulation of the ballistic impact of shear thickening fluid (STF) impregnated with ultra-high molecular weight polyethylene (UHMWPE) fiber composites. The STF/UHMWPE composites pull-out test results are fitted to obtain a similar STF rheological curve. The STF/UHMWPE composites fluid-structure interaction (FSI) model was established to reproduce the local failure and stress distribution at each stage of the ballistic impact process. The comparison of the finite element analysis (FEA) and the experimental results showed that the fitting degree of the STF/UHMWPE composites to the impact energy absorption was 94.74%. STF treatment has dual effects on the impact resistance of fabrics, increasing the friction and enhancing the thickening effect. more...