摘要: Given their varied physiological and ecological attributes, phytoplankton frequently exhibit disparate responses to changes in environmental conditions. Therefore, when studying modifications in the structure of a phytoplankton community, it is necessary to consider such differences and investigate the underlying mechanisms. Through a field sampling study of 26 lakes, we found that the differing responses of phytoplankton to changes in environmental factors were partly related to their genome size. The Cyanobacteria and Chrysophyta, which possess smaller genomes, exhibited a relatively low degree of sensitivity to alterations in nutrient concentrations. However, they demonstrated a stronger dependence on the metabolic processes of environmental microorganisms compared to other phytoplankton with larger genomes. Furthermore, the Cyanobacteria and Chrysophyta were more closely associated with environmental nutrients and water chemistry and were more actively involved in interspecific interactions among phytoplankton. By randomly deleting sample points, we verified the generality of the above conclusions. However, more refined grouping analyses indicate that diatoms exhibited different ecological characteristics due to their physiological and morphology. The present study offers new insights into the mechanisms underlying the ecological adaptations of phytoplankton and may provide new guidance for the management of Cyanobacterial blooms. Further studies could take a more refined approach to investigate the effect of phytoplankton effective genome size on their adaptive capacity.

摘要: Hypoxia is one of the major environmental stressors, frequently resulting in serious yield losses for maricultured large yellow croaker (Larimichthys crocea). We know that pyroptosis contributes to tissue damage under hypoxic conditions. However, whether GSDMEs-mediated pyroptosis is involved in hypoxia-induced tissue damage in fish remains unclear. In the present study, two Lcgsdme genes, Lcgsdmea/b, were cloned and characterized from the large yellow croaker. Both genes contain a conserved N-terminal pore-forming domain, a C-terminal autoinhibitory domain, and a flexible hinge region. After hypoxia stress, the expression of Lcgsdmea/b transcripts and proteins in the liver were significantly higher than in unstressed fish. The proteins of LcGSDMEa/b could be cleaved under hypoxic conditions. Compared to LcGSDMEb, the expression of LcGSDMEa was higher in both mRNA and protein levels, thus exhibiting a stronger response during hypoxia stress. Furthermore, after 48 h of hypoxia stress, approximately 65% liver cells exhibited abnormalities, with pyroptosis being detected using a transmission electron microscope. TUNEL/LcGSDMEa double staining assay revealed a high expression of LcGSDMEa in the dead cells. We observed a significant up-regulation of pyroptosis pathway genes (asc, caspase-3) and pro-inflammatory cytokine genes (il-1 beta, il-18). After simultaneous knockdown of Lcgsdmea/b in vivo, the liver exhibited better health compared to the control group, with less cell swelling and vacuolation. Taken together, these findings demonstrate that hypoxia stress could activate LcGSDMEa/b and induce pyroptosis in the liver of large yellow croakers, thereby contributing to tissue damage. Our study improves the understanding of hypoxiainduced tissue damage in fish, and provides new clues for protecting fish against hypoxia-induced damage.

摘要: Aquaculture of red swamp crayfish Procambarus clarkii is an emerging farming industry in China. As shown recently, one of the most significant diseases affecting the red swamp crayfish is caused by overabundance of epibiotic peritrichs, a group of ciliated protists that are commonly found living as epibionts on aquatic animals. Nevertheless, few studies focusing on this issue have been performed. As part of a faunal study carried out in the Lake Weishan Wetland, China, four colonial sessilid peritrichs, namely Epicarchesium granulatum, Epistylis bimarginata, Epistylis semiciculus, and Zoothamnium procerius, attached to P. clarkii are documented. For each species, redescriptions and improved diagnoses are supplied. As a further aid to identification, 14 new rDNA sequences of these four and a closely related species were obtained. In addition, as an aid for future studies on epibiotic ciliates, we supply a list and information about recent integrative studies that document the geographic distributions of related taxa.

摘要: Freshwater aquaculture plays an important role in the global aquaculture industry. The success of freshwater aquaculture relies on the integration of bio-ecological remediation technologies to ensure its sustainable development. This paper systematically reviews the global literatures on bio-ecological remediation of freshwater aquaculture environments from 1990 to 2021, and discusses in detail the research progress and status quo in this field using both bibliometric analysis and content analysis. Our results indicate that the number of publications per year has increased year by year, with a particularly rapid increase after 2015. Institutions and researchers from China and the USA publish the greatest number of papers and contribute the most to this field. By analyzing the research progress in this field, we also find that the protection and restoration of freshwater aquaculture environments has received attention since as early as 1990, such as the application of constructed wetlands and recirculating aquaculture systems. Recently, researchers have increasingly focused on the use of microbial communities in remediation. Furthermore, vanRijn, J's papers are of great value to the research in this field. In content analysis, the application of primary technologies, including plant selection, aquatic animals, microorganisms, and biological filtration and purification equipment, as well as ecological engineering technologies with combinations of various types of organisms, is described to improve the effectiveness and efficiency of remediation. The performance, advantages, disadvantages, or limitations and prospects of these technology applications are analyzed in detail. By comparison, ecological engineering is shown to be the best remediation technology, being most comprehensive, and well-established. Taken together, this paper composes and summarizes existing work in this field, and provides guidance for future research on the improvement of existing technologies and the development of new technologies, with the aim of enhancing remediation capability, improving ecological sustainability and ensuring economic viability.

摘要: Fish passage facilities are constructed worldwide to enable fish to pass anthropogenic obstacles (i.e., dams) and re-establish river connectivity. The construction of these facilities involves sophisticated engineering designed to attract fish and enable passage. The behavior of fish encountering these structures, particularly in long vertical slot fishways, has been poorly studied. This study was conducted on the Daduhe River in Southwest China to quantify the upstream passage efficiency and performance of tagged Schizothorax davidi in different sections of a long vertical slot fishway spanning 1228.3 m. The overall passage efficiency was 13% although the passage efficiency in seven sections (A0-A1, A1-A2, A2-A3, A3-A4, A4-A5, A5-A6, A6-A7) ranged from 43% to 100% reflecting differences in slope among sections. The highest passage efficiency was documented in rest pool sections with a slope of 0 (A3-A4, 100% and A6-A7, 100%) and during passage through the dam itself (A5-A6, 90.0%). The lowest passage efficiency was section A2-A3, where a garbage interception facility affected passage efficiency. Average transit time from A0 to A7 was 85.2 h and ranged from 8.8 to 237.6 h. Transit speed varied over various sections. The first section (i.e., A0-A1) had slow transit speeds which presumably was influenced by acclimation and recovery from tag implantation. After this, the transit speed had a slight increase but decreased again. Additionally, more than half (5 out of 9 fish) of the fish fell back after reaching the most upstream section and reascended the fishway which tripled the total passage time for those individuals. No significant diel activity rhythms were observed, but a strong bimodal distribution was noted in fish transit time when passing the first monitoring site. Cox-proportional hazards model showed that transit time was negatively correlated with body size but positively correlated with water level and water temperature. Our study provides valuable insights into activity when passing through a long fishway, which can inform design of fishway structures and operational patterns to improve upstream passage efficiency. Specifically, we recommend increasing the number of resting pools and maintaining appropriate water levels to reduce transit time and fallback frequency in long fishways.

摘要: Seahorses are specialized teleosts due to their unique male pregnancy and reproductive physiology. In particular, they have distinct gonad structures and different patterns of gametogenesis development in both sexes. However, the molecular mechanism of germ cell development in seahorses remains unknown. Nanos, which encodes conserved zinc-finger RNA-binding proteins, play essential roles for germline development in both vertebrates and invertebrates. In this study, we characterized the nanos gene family members and their potential roles in germline development in the lined seahorse, Hippocampus erectus. We showed that the nanos family members in the seahorse are the nanos1a, nanos1b, and nanos3 genes, while nanos2, a key germline stem cell (GSC) maintenance factor, is intriguingly absent. More interestingly, nanos3, which is reported to be a female-specific gene, was also highly expressed in male gonads, as well as in the early developmental stages of testes and ovaries. Our results also showed that nanos3 was highly expressed in early meiotic germ cells, and that expression levels of nanos3 were lower in the gonad after TBT exposure. These findings suggest that nanos3 may function during male germ cell development, and in female initial germ cell production - processes which are regulated by nanos2 in other teleosts. This is the first research into how nanos governs germ cell development in an ovoviviparous fish. Our study provides insights into the regulatory mechanisms of germ cells development, as well as the early events during gametogenesis in the family Syngnathidae.

摘要: The Chinese soft-shelled turtle (Pelodiscus sinensis) exhibits sexual dimorphism. Compared with females, males are considered to have higher economic value due to their accelerated growth, greater body mass, and longer skirt width. Studies focused on these sex disparities have largely neglected potential sex differences in growth. Here, we performed RNA sequencing of muscle tissue components from 1-year-old specimens to reveal gene expression patterns in P. sinensis. In our male and female cohorts, our analysis revealed, respectively, 388 and 526 upregulated differentially expressed genes (DEGs) and 1129 and 635 downregulated DEGs. Through weighted coexpression network analysis (WGCNA) and integration with phenotype data, we established two main gene modules: a light yellow module encompassing 191 genes (e.g., ACACB, CTH, HADHA, and CTNNB) that demonstrated a positive correlation with population traits, and a black module comprising 298 genes (e.g., CAV3, PIK3CD, SMAD3, and VEGFA) that demonstrated a negative correlation with population traits. We also performed a DEG evaluation and gene set enrichment analysis across individuals of different sizes and noted that pathways such as protein digestion and assimilation (ko04974), were substantially augmented in larger specimens. In these pathways, the collagen (COL) and solute carrier (SLC) gene families were noted to be crucial for sustaining body structure and facilitating nutrient and metabolite transportation. In conclusion, we elucidated the essential modules, pivotal genes, and pathways involved in gene expression differences among various P. sinensis size groupings. Our results provide novel insights for future studies on growth discrepancies in P. sinensis.

摘要: Aeromonas salmonicida is a common pathogen of salmonid fishes that poses a significant threat to the fresh water and marine culture industry, potentially resulting in huge economic losses. To prevent and control fish diseases caused by A. salmonicida , rapid and effective diagnostic approaches must be developed, and which are important for routine monitoring and clinical care. By combining recombinase polymerase amplification (RPA) technology with a visible lateral flow strip (RPA-LF), we have enhanced both the precision of RPA detection and the convenience of real-time monitoring. In this study, we introduce a robust method for detecting A. salmonicida using RPA-LF. This assay specifically targets the ASA_1441 gene of A. salmonicida , ensuring high specificity, without cross-reactivity with other prevalent fresh water or marine pathogens. The optimal amplification temperature of the RPA assay was 39 degrees C. Its sensitivity extends to as low as 100 fg of purified DNA, representing more than 1000fold higher sensitivity than conventional PCR methods. Furthermore, to enhance the usability of the RPA-LF assay, we developed a rapid sample preparation method using cellulose dipsticks for nucleic acid extraction. This method achieves a limit of detection (LOD) as low as 1.67 CFU/ mu L and completes the entire process within 20 min. In conclusion, our findings present a rapid and precise tool for monitoring A. salmonicida infection in aquaculture and marine culture. This advancement offers valuable insights for effective disease prevention and control strategies.

摘要: The intestine serves as the primary digestive and essential mucosal immune organ, harboring diverse microbiota that play crucial roles in digestion, absorption, and host immunity. However, the association between the intestinal microbiota and host growth and immunity remains insufficiently established, particularly in ectothermic animals where microbiota are easily influenced by external environments. Herein, a comparative analysis of histology, gene expression, transcriptome, and microbiome was deployed to systematically investigate the potential relevance of growth traits, immune responses, and gut microbiota between Reeves' turtles with inferior (IGP) or superior growth performance (SGP). Our results revealed that, in comparison to the IGP group, the SGP group exhibited histological intestinal structures that were more conducive to digestion and absorption, thereby aligning with its superior growth traits. Moreover, transcriptomic annotation identified 50 differentially expressed genes (DEGs) associated with growth and 70 DEGs involved in immunity. These DEGs showed significant enrichment in growth- and immunity-related GO terms and KEGG pathways. Further RT-PCR analyses validated the expression profiles of several genes related to growth and immunity across multiple tissues. In addition, analysis of microbial abundance revealed the presence of various sensitive indicator genera, such as Lactobacillus and Brevundimonas, which potentially imply host growth performance and immune response. At the phylum level, a more diverse and stable microbial interaction between intestinal microbiota in the SGP group and aquaculture water was predicted to contribute to superior growth performance and immunity. Furthermore, correlation analyses revealed a potential interplay between indicator genera with DEGs associated with growth and immune responses. Taken together, these findings highlight the intricate interplay of intestinal microbiota, environmental microbiota, as well as growth- and immunity-related genes in shaping host traits, providing valuable insights into promoting healthy culture practices for Reeves' turtles from both molecular and microbiological perspectives.

摘要: Water level variations (WLVs) substantially affect the spatial distribution of riparian vegetation. Accurately quantifying the water level fluctuation requirements (WLFRs) of aquatic macrophytes is essential for effective ecological water level management. Nevertheless, studies on the WLFRs of herbaceous plants in large river floodplains, such as Phragmites australis (common reed) and Phalaris arundinacea (reed canarygrass), are limited. Herein, we investigated the WLFRs of the two plants across water bodies with different WLVs in the Yangtze River Basin. We focused on the effects of sub-monthly and sub-daily WLVs on their average monthly water depth requirements (WDRs) during critical growth periods. Our findings indicated: (1) For Phragmites, during the emergence period, the upper limits of WDRs decreased with increased amplitudes of sub-monthly WLVs and with greater frequency and amplitude of sub-daily WLVs, in which sub-daily variations had a more pronounced effect. Conversely, during the rapid growth period, the upper limits increased with larger sub-monthly WLVs amplitudes, but decreased with higher frequency and amplitude of sub-daily WLVs. (2) For Phalaris, during both the emergence and rapid growth periods, intensified sub-daily WLVs led to decreased upper limits of WDRs. In summary, although distinct disparities existed in the WLFRs of Phragmites and Phalaris across various water bodies, the trends in WDRs during the emergence and rapid growth periods were consistent for both species. These findings provide essential quantitative data to restore aquatic vegetation and carry out effective ecological water level management in large-scale riparian ecosystems.