摘要: Marine microplastics (MPs) are an increasingly important concern worldwide. This study aimed to investigate the occurrence and characteristics of microplastics in an intertidal sea snail, the common periwinkle (Littorina littorea) sampled from Saint Martin's Island, Bay of Bengal. The results revealed that 100% of the common periwinkle snails ingested microplastics (MPs), with a mean abundance ranging from 2.63 +/- 1.07 to 23.89 +/- 3.53 MP/g (average: 7.76 +/- 5.77 MP/g). Microplastic particles in the 100-1500 mu m size class were the most abundant (63%), whereas black and red fibers were the most abundant colors and shapes. Polypropylene (PP, 34%) and polyethylene (PE, 38%) were the major polymer types, followed by polystyrene (PS, 15%) and polyethylene terephthalate (PET, 13%). Although the polymer hazard index (PHI) showed risk categories III to IV due to highly hazardous polymers such as PS and PE in the soft tissue of the common periwinkle snails, the pollution load index (PLI <10) revealed minor contamination across the sampling site of Saint Martin's Island. Gastropod feeding patterns and food items impacted MP abundance in the studied area.

摘要: The ricefield eel (Monopterus albus), a protogynous hermaphrodite, is an important aquaculture freshwater fish in China. Intensive studies have focused on the sex reversal of this species, but the underlying mechanisms remain elusive. We performed comparative transcriptome analysis for gonadal tissues of female, intersex, and male ricefield eels. The results suggest that temperature may play a role in inducing the sex reversal. Moreover, an epithelial-mesenchymal transition (EMT) gene signature was found, suggesting an involvement of germinal epithelium in contributing to gonadal transformation. Our in vitro and in vivo experiments show that thermal cues are sensed by thermosensors such as Trpv4 in the gonadal cells of ricefield eels, which can be transduced to the sex determination cascades. The epithelial cells of germinal epithelium can become Sertoli cells via an EMT. Our study provides new insights into the molecular mechanisms underlying the sex reversal of ricefield eels.

摘要: Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morphological characterization and phylogenetic tree based on the rbcL gene confirmed its attribution to Heribaudiella fluviatilis. The complete organelle genomes of H. fluviatilis were determined and assembled from highthroughput sequencing. A circular tetrad structure of 128,880 bp was identified for the chloroplast, and the mitochondrial genome was assembled as a circle with 43,657 bp in length. This study provides the first and only record of organelle genomic information of the freshwater Phaeophyceae, which are important for understanding the endosymbiosis theories. Concatenated (Bayesian inference, maximum likelihood under MFP and GHOST models) and coalescent methods were used to construct the phylogenetic relationship among secondary plastidbearing lineages based on organelle genomes. Obvious conflicts were observed in grouping relationships of chloroplast and mitochondrial genomes, even among different evolutionary models and tree-constructing methods. The transcriptome of H. fluviatilis was sequenced and used to construct the phylogenetic relationship among secondary plastid-bearing lineages. The phylogenetic relationships in nuclear and mitochondrial genomes were consistent in grouping CHSR taxa (cryptophytes, haptophytes, stramenopiles and rhizarians) in an independent branch. The phylogenetic relationship constructed from nuclear transcriptomes was highly reliable by owning robust supporting values on each node and was consistent with the serial endosymbiosis theory on evolution of red secondary plastid-derived lineages.

摘要: The objective of this study is to investigate the effects of free gossypol in cottonseed meal (CM) on the growth and intestinal health of grass carp, as well as to determine whether free gossypol is the primary factor restricting highlevel inclusion of cottonseed meal. This study was designed with five groups: the control group (32% soybean concentrate protein), the CM group (44% CM), the cottonseed protein concentrate (CPC) group (33% CPC), and the CPC and control groups with 400 and 600 mg/kg gossypol added, designated as CON, CM, CPC, CPC & thorn; GP, and CON & thorn; GP, respectively. The experiment lasted eight weeks, and each group had three replicates. This experiment employed one-way ANOVA and Duncan's multiple comparisons of the means. The findings revealed that in comparison to the CON group, the growth of fish in the CM, CPC & thorn; GP, and CON & thorn; GP groups significantly decreased. Intestinal inflammation damage was observed. This was indicated by a significant upregulation of pro- inflammatory factors, including tnf-alpha, nf-kappa b, il-6, il-8, il-12/3, and il-1/3, along with significant downregulation of anti-inflammatory factors, including tgf-/31, il-15, and il-10. Additionally, significant downregulation of antioxidant enzyme-related genes, including nrf2, cat, CuZnsod, gpx4, and gpx1, was observed and the intestinal physical barrier function was compromised. In addition, the intestinal microbiota composition was affected, with a significant reduction in Bacillus and Cetobacterium abundances and a remarkable increase in the abundance of Aeromonas, resulting in dysregulation of the intestinal microbiota function. However, in comparison to the CM group, the growth rate of fish in the CPC group exhibited a marked increase; nonetheless, it persisted at a level lower than that observed in the CON group and the degree of intestinal damage was significantly improved. Additionally, the intestinal microbiota structure was found to be similar to that of the CON group. In conclusion, excessive CM negatively affects grass carp growth and intestinal health, whereas replacing CM with CPC mitigates these effects. Adding gossypol equivalent to CM group in CON and CPC diets reduces growth performance and impairs intestinal function, indicating gossypol as a primary limiting factor for high CM inclusion in diets.

摘要: Frequent outbreaks of emerging infectious diseases in fish, such as Carassius auratus herpesvirus (CaHV) infection has caused great economic losses in China. However, the lack of a sensitive cell culture system has limited studies of CaHV. In the present study, a new cell line (gibel carp skin cell, GiCS) derived from gibel carp ( Carassius gibelio ) skin tissue was established to create a valuable tool for research of the virus. The GiCS cells consisted mainly of epithelial-like cells, which grew well at 25 degrees C in L-15 medium supplemented with 10 -20% fetal bovine serum. Chromosomal analysis revealed that the skin cell line remained amphitriploid, with most chromosome counts being 156 (54%). The GiCS cells can be efficiently transfected and expressed exogenous genes. In particular, the GiCS cells showed high susceptibility to CaHV infection, which was confirmed by virus infection tests, detection of viral gene expression, and ultrastructural observation. To our knowledge, it is the first cell line that is highly permissive to CaHV infection. In addition, the cells also showed susceptibility to several aquatic animal viruses from different families including Iridoviridae , Rhabdoviridae , and Reoviridae . In conclusion, these results indicated that the establishment of the GiCS cell line isa significant advance that will be beneficial to future studies of CaHV and other aquatic animal viruses.

摘要: Filamentous algae blooms (FABs) have been increasing globally in recent years, and their presence can have both harmful and beneficial effects on aquatic ecosystems. As one of the most common FABs, Cladophora blooms have been reported in the lakes of the Qinghai-Tibet Plateau during the past few years. However, there have been few studies focused on how FABs impact other aquatic organisms, especially in alpine lakes since these are at the forefront of responding to global climate change. In this study, the phytoplankton communities in different regions of Qinghai Lake were profiled in different seasons using meta-barcode sequencing. The phytoplankton assemblages in areas with Cladophora blooms were compared to those without Cladophora. The phytoplankton community structure correlated with physicochemical properties including water temperature, electrical conductivity, nitrate, and the presence or absence of Cladophora blooms. The relative abundance of Bacillariophytes was found to be higher in zones with Cladophora blooms than in other regions. Significant seasonal changes in phytoplankton biomass and beta diversity were observed in zones with Cladophora blooms. Growth and microbial degradation of Cladophora can change the pH, dissolved oxygen, secchi depth, and nitrate. Together with seasonal temperature and electrical conductivity changes, Cladophora growth can significantly impact the phytoplankton biomass, community dissimilarity and assembly process. These results showed that Cladophora plays a key role in littoral aquatic ecosystem ecology.

摘要: High-mountain stream ecosystems are recognized as ideal arenas for natural experiments and for ecological monitoring and assessment research, owing to their sensitivity to climate gradients and human-mediated disturbances. In this study, we chose a subtropical mountainous stream system in southwestern China, to explore the spatiotemporal patterns and driving factors of taxonomic, phylogenetic, and functional beta diversity of macro-invertebrate assemblages. We found that taxonomic beta diversity was highest (on average, 0.577 in spring and 0.645 in autumn) across seasons, followed by phylogenetic (0.491 and 0.545) and functional (0.350 and 0.383) beta diversity, with the replacement component predominantly (57%-73%) contributing to all three facets of diversity. The taxonomic local contributions to beta diversity (LCBD) values were roughly equivalent among different sites in both spring and autumn, whereas phylogenetic LCBD (PLCBD) and functional LCBD (XLCBD) indices varied from site to site. Therefore, we recommend prioritizing site conservation based on LCBD, PLCBD, and XLCBD values to optimize biodiversity conservation strategies. The three-facets of dissimilarities were all somewhat higher in autumn than spring, possibly due to recolonization events in the metacommunity after the summer flood. Variation partitioning analysis indicated that environmental factors were more important than spatial factors in structuring all three facets of beta diversity and their components, although different sets of variables were identified as important for different diversity facets and between seasons. In summary, our study offers valuable insights into the patterns and drivers of macroinvertebrate beta diversity in high mountain streams and lays a baseline for targeted conservation strategies in these ecosystems.

摘要: Proteins in aquatic products satisfy the increasing demand of high-quality proteins of humans, resulting in a rapid development of freshwater aquaculture. However, bacterial diseases in aquatic animals often cause economic losses worldwide. Antibiotics are frequently used in aquaculture to deal with bacterial infections, but antibiotic resistance has restricted its application. Therefore, it is necessary to develop drugs on account of novel strategies. Here, aerolysin, the main virulence factor of Aeromonas hydrophila (A. hydrophila), was defined as a target to develop anti-virulence drugs. The results showed that Licochalcone A (LCA) with little bacteriostatic activity could decrease the hemolytic activity of aerolysin without affecting its production. The binding mode and potential binding sites were determined following molecular docking and dynamic simulation. Ser33 and Pro365 were confirmed to be the main binding sites according to the results of fluorescence quenching assay with mutated aerolysin. The mechanism by which LCA inhibited aerolysin was hindering its pore-forming activity. Moreover, cell viability assays and animal studies demonstrated that LCA could provide a significant protection to human alveolar epithelial cells from aerolysin-mediated cell damage and decrease the pathogenicity of A. hydrophila to channel catfish. These findings suggested that LCA might be a novel candidate for treating A. hydrophila infections and partly determined the mechanism of herbal medicine in dealing with bacterial infections.

摘要: The presence of microplastics in the marine environment poses a potential threat to juvenile and adult sea cucumbers; however, the effects of microplastics on the early developmental stages of sea cucumbers are poorly understood. In this study, the larvae of Holothuria leucospilota were exposed to polystyrene (PS) particles of varying sizes (1-60 mu m) to investigate the influences of microplastics on food ingestion, digestion, and performance of larval H. leucospilota at different developmental stages. The fluorescence tracing experiment revealed that the early- and mid-auricularia were capable of ingesting particles up to 20 mu m in size, whereas lateauricularia larvae could ingest particles up to 40 mu m in size. It was observed that microplastic particles accumulated in the stomach of larvae over a certain period, making it difficult for them to eliminate. Microplastic particles of 10 mu m could be observed aggregating in the stomach of larvae at all developmental stages. The 20 mu m and 40 mu m particles had limited effects on larval survival but caused developmental retardation. Larvae that were exposed to 10 mu m and 60 mu m particles had significantly lower survival rates compared to the control group. Moreover, microplastics had a negative effect on the growth of larvae, and larger particles (20 mu m, 40 mu m and 60 mu m) had greater effects than smaller ones (1 mu m, 5 mu m and 10 mu m). The presence of microplastics hindered the development and metamorphosis of larvae, in particular by inhibiting the maturation of their ciliary band and esophagus. In conclusion, microplastics have negative impacts on larval H. leucospilota, and therefore, effective measures should be taken to prevent the introduction of microplastics into hatcheries artificially breeding sea cucumbers.

摘要: Twenty USA states or jurisdictions and 125 nations have modeled national environmental policies after the National Environmental Policy Act. That act mandates that federal agencies initiate environmental impact statements (EISs) when substantive environmental or human health consequences are likely because of an agency action related to proposed development projects. The science used to inform the EIS process, however, does not require independent scientific peer review (ISPR) in the USA or most other nations. But ISPR is needed for governments to accurately inform the EIS decision-making and public reporting processes. Instead, science is routinely manipulated during EIS reviews to generate expedient project outcomes with substantially negative ecological, political, and long-term economic consequences. We provide four examples of EISs that lack ISPR, as well as four examples where reviews by independent scientists were helpful to improve agency decisions. We also recommend that independent scientists (no affiliation with the project proponents or agencies overseeing projects) be used to help assess potential environmental and socio-economic impacts, as well as offer appropriate risk assessments, study designs, and monitoring timeframes. We conclude that nations should convene formal reviews using independent scientists as a form of peer review in the EIS process.