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: Lotic ecosystems are especially vulnerable to the adverse effects of urbanization because of their close connectivity with the surrounding terrestrial ecosystems. There is, however, a knowledge gap in how the taxa and functions of benthic macroinvertebrate assemblages respond to a gradient of urban land use and where their tipping points are along this gradient. Thus, we quantified how urban land use in stream catchments influenced benthic macroinvertebrate assemblages functionally and taxonomically. We found that urbanization affected benthic macroinvertebrate assemblage taxa and functions at tipping points of <10% of stream catchment urbanization. Greener human settlements are needed to minimize losses of sensitive macroinvertebrate taxa and their functions.

摘要: Nature reserves in the Yangtze River, China, are crucial for protecting the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) and their habitats. Despite a 10-year fishing ban along the middle and lower reaches of the Yangtze River instated on January 2020 to alleviate pressures on the porpoise's prey, other stressors, particularly underwater noise, continue to impact these rare cetaceans, which rely heavily on vocalization for prey detection, communication and navigation. Between September 2020 and September 2021, underwater noise monitoring was carried out in the Xinluo Baiji National Nature Reserve, located in Hubei province, China, with the aim of assessing the potential impact of underwater noise pollution on the Yangtze finless porpoise. The reserve was divided into 30 sub-sections to systematically monitor underwater noise across the reserve. Passive acoustic monitoring was conducted at each site within these sub-sections during four sampling periods, and these data were subjected to comparative analysis with data collected in 2012 and 2017. The results showed that the root mean square sound pressure levels at each site ranged from 117 to 162 dB. Power spectral levels (11.2-152 kHz) exceeded the average audiogram levels for the porpoise at most sites. 94.2% and 93.3% of the sites exceeded underwater acoustic thresholds known to induce a hearing threshold shift for the porpoise in terms of both the averaged cumulative unweighted sound exposure level, and cumulative weighted sound exposure level respectively. Noise levels in this section during 2020-2021 were approximately 25 and 30 dB higher compared to the levels recorded in 2012 and 2017, and likely due to increased shipping activity and the proximity of sampling sites to the shipping channel. The rise in noise levels might contribute to the observed declines in the porpoise population within this area. To mitigate these impacts, implementing noise control measures is essential, such as regulating navigation speed and limiting the number of vessels in the reserve.

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: Biological invasions threaten water resources worldwide owing to interrelated biological and anthropogenic drivers of change. Though the role of people in the (un)intentional spread of aquatic invasive species is increasingly recognized as a priority, there are widespread assumptions about the importance of public awareness in explaining biosecurity behaviors. A disconnect exists between what people think and what they do-as articulated by the simple but powerful knowledge-action gap-that warrants attention to clarify how environmental social science research can most effectively advance invasive species prevention. Using survey data collected from aquarium hobbyists in the U.S. state of Illinois, we investigated the role of belief systems in shaping intentions to engage in biosecurity behaviors, such as purchasing only native species as pets. We also examined how beliefs were rooted in multiple forms of knowledge. Self-efficacy was the strongest driver of intended biosecurity behavior, whereas both perceived benefits and risk perceptions were instrumental in explaining hobbyists' decisions. Beliefs were informed by two types of reported knowledge, which in turn, were influenced by a range of information sources. Our results suggest that a more nuanced conceptualization of public awareness is urgently needed given its critical but often misunderstood role in the formation of beliefs that influence participation in biosecurity behaviors. Knowledge of both biological invasions and biosecurity behaviors, in addition to information sources, needs to be distinguished in future research. These multiple forms of knowledge serve as the foundation for belief systems that activate behavior change among aquarium hobbyists. We also argue that science communication and outreach campaigns that highlight the risks of invasive species while strengthening selfefficacy and perceived benefits of prevention will be the most effective pathways for fostering hobbyist engagement in biosecurity behaviors.

摘要: Members of the genus Hypotrichidium are adapted to a planktonic lifestyle and are characterized among hypotrichs by their unique pyriform body with pointed tail and spiral cirral rows around the whole body. During a survey of Korean freshwater ciliates, we discovered a new Hypotrichidium species that changes its cortical granules color. Observations on the morphology and behavior of Hypotrichidium bichromum n. sp. revealed several other unusual features such as the polymorphic life cycle and cannibalistic behavior. When grown in a fresh culture, well-nourished specimens are characterized by a pyriform body, yellow cortical granules, and two macronuclear nodules. In declining cultures, two morphologically different morphs occur, both with ruby-red cortical granules: (1) a well-nourished morph with a pyriform body and 2-4 macronuclear nodules, which shows a cannibalistic behavior feeding on other well-nourished cells, encysting cells, and reorganizers; (2) a fast-swimming, non-feeding morph with slender body, two macronuclear nodules, and highly degenerated undulating membranes. The complete ontogenetic process of the new species is described to show the origin of each structure. Moreover, phylogenetic analyses based on 18S rRNA gene sequences show that the new species is placed in a clade containing sequences of three congeners.

摘要: The largemouth bass virus (LMBV) exhibits high pathogenicity in both adult and juvenile largemouth bass, causing substantial economic losses within the aquaculture industry. MicroRNAs (miRNAs) are crucial in controlling viral infections and the host's immune responses, making them significantly valuable in the treatment and diagnosis of diseases. Nevertheless, research on miRNA expression profiles associated with LMBV infection in largemouth bass is currently insufficient. This research attempts to investigate the roles and molecular mechanisms of miRNAs in the potential immune response and metabolic alterations triggered by LMBV infection in largemouth bass using miRNA sequencing. Following quality screening, the infection group and control group yielded a combined total of 142.73 million clean reads, with lengths predominantly at 22 nt. 1718 known miRNAs were identified, including 238 differentially expressed miRNAs (DEMs). In addition, 400 novel miRNAs were predicted, 36 of which were DEMs. To gain further insight into the immune and metabolic related biological functions of DEMs, target gene prediction was conducted. KEGG pathway analysis revealed that LMBV impacted pathways such as Endocytosis, Purine metabolism, Phosphatidylinositol, Fatty acid Biosynthesis, and Phagosome signaling systems, highlighting the vital role of miRNAs in immune responses and metabolic alterations. Furthermore, the miRNA-mRNA interaction network revealed crucial miRNAs and their corresponding target genes involved in conferring resistance against viral infections by utilizing metabolic and immune related pathways as the foundation. Ten DEMs were selected at random for real-time quantitative PCR (qRT-PCR), and results exhibited expression patterns that were consistent with sequencing data. These findings validate the immune and metabolic regulatory function of miRNAs against LMBV in largemouth bass, offering valuable perspectives for the prevention and management of illnesses linked to iridoviruses.

摘要: Olfaction, the sense of smell, is vital for the survival of many species and serves as an excellent system for investigating the molecular basis of behavior. Fishes possess a well-developed olfactory system that governs various behaviors related to feeding, reproduction, and fear. However, the cellular diversity and heterogeneity of the fish olfactory epithelium remains largely unexplored. This study presents a single-cell atlas of the zebrafish olfactory epithelium using single-cell RNA sequencing (scRNA-seq). Through scRNA-seq analysis of approximately 10,587 cells, we identified nine distinct cell types with unique transcriptional profiles, including immature and mature olfactory sensory neurons (OSNs), horizontal basal cells, globose basal cells, and sustentacular cells, as well as lymphocyte and myeloid cells expressing immune signals. Further subcluster analysis revealed selective and combinatorial expression of key components in odorant-mediated signal transduction by distinct OSN populations. Additionally, we discovered transcriptional changes specific to certain OSN populations following exposure to a conspecific alarm substance. The single-cell transcriptional atlas of the zebrafish olfactory epithelium provided in this study serves as a valuable tool for exploring cell diversity and assessing genetic profiles from functional and behavioral perspectives in fish.

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: 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.