摘要: eDNA-based methods offer a non-invasive, easy-to-use approach for monitoring aquatic biodiversity, particularly for tracking invasive or cryptic species. While Illumina sequencing is commonly used, few studies have explored pairing eDNA sampling with Nanopore sequencing, a third-generation technology that allows for on-site sequencing but with a higher error rate. Here, we compared the performance of both technologies in detecting the invasive host-parasite complex Pseudorasbora parva-Sphaerothecum destruens. Water samples were collected from sites in Camargue and Corsica (Southern France), followed by DNA extraction, PCR amplification, and sequencing using either Illumina or Nanopore. Both technologies showed similar detection rates of P. parva, but only when Nanopore sequencing was performed under optimal conditions. However, for S. destruens, results varied: Illumina failed to detect the parasite, while Nanopore identified its DNA in multiple sites. We suggest that this discrepancy may be due to the different bioinformatic approaches used to process the reads and/or the higher error rate of Nanopore sequencing which could result in misassignments during species identification.

摘要: The Atlantic killifish Fundulus heteroclitus represents a remarkable estuarine model for studying physiological adaptation to environmental stress and even industrial pollution. Assessing cell death, including apoptosis and necrosis, is essential to understanding its phenotypic plasticity and adaptability. However, previous studies predominantly focus on apoptosis, while the regulation of necrosis remains largely unexplored. Pyroptosis is a type of regulated necrotic cell death executed by the pore-forming protein, gasdermin. Herein, we revealed the presence of three phylogenetically segregated gasdermin E (GSDME) homologs, designated GSDMEa/b/c, in killifish. All three GSDME orthologs harbor the pore-forming N-terminal domain, which is capable of perforating the cell membrane and inducing pyroptosis. Mechanistically, GSDMEa is activated by the cleavage of proinflammatory caspase-1 and apoptotic caspase-3/7, GSDMEb is proteolytically activated by proinflammatory caspase-1 and apoptotic caspase-3/7/8, while GSDMEc specifically relies on activation by apoptotic caspase-7. Following cleavage, the pyroptosis-inducing NT fragment is liberated from the auto-inhibitory C-terminal domain, and executes pyroptosis with massive release of intracellular contents. Site-directed mutagenesis reveals that GSDMEa and GSDMEb possess evolutionarily conserved functional residues required for pore-forming activity, whereas the functional residues involved in the C-terminal auto-inhibition are highly diverged among these three orthologs. Our findings collectively unveil a sophisticated and intertwined signaling pathway in regulating killifish pyroptosis, improving our understanding of cell death in killifish phenotypic adaptability and plasticity.

摘要: Recirculating aquaculture systems (RASs) are recognized for their eco-friendly and efficient approach in aquaculture. This study constructed a novel system: a land-based tank aquaculture system coupled with effluent treatment ponds (LBTAS). The system includes land-based tanks, an oxygen supply system, a water inlet system, a sewage collection system, and an effluent treatment system. We evaluated the impact of different stocking densities on the growth, health, aquaculture yield, and economic benefits of gibel carp (Carassius gibelio) in the LBTAS. The yields of the high stocking density (HSD) group and the low stocking density (LSD) group were similar, which was more than three times that of traditional pond farming. But the LSD group significantly improved final weight (FW), final length (FL), weight gain ratio (WGR), specific growth rate (SGR), feed conversion ratio (FCR), ingestion rate (IR), and viscerosomatic index (VSI) compared to HSD groups (P ​< ​0.05). While survival rates and the hepatosomatic index (HSI) were similar across groups, the low-density group exhibited better overall health. Serum biochemical indicators such as glucose (GLU), cholesterol (CHO), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) were unaffected by density. However, levels of alanine aminotransferase (ALT), triglycerides (TG), lactate acid (LD), and cortisol were significantly higher in the HSD group (P ​< ​0.05), indicating increased stress. Hepatic antioxidant analysis showed stable levels of glutathione peroxidase (GSH-PX) and total superoxide dismutase (T-SOD), but higher levels of catalase (CAT) and malondialdehyde (MDA) in the high-density group (P ​< ​0.05), suggesting increased oxidative stress. Muscle histology analysis revealed significantly higher muscle fiber density in the LSD group (P ​< ​0.05), with no significant effect on muscle fiber diameter. Water quality analysis indicated poorer quality in the HSD group, with lower dissolved oxygen and significantly higher concentrations of total phosphorus (TP) and nitrite nitrogen (NO2⁻-N) compared to the LSD group (P ​< ​0.05). Despite the initial lower cost, the LSD group achieved a higher economic return on investment (ROI) of 16.92%. Our research results demonstrate that the aquaculture yield of gibel carp in the LBTAS is more than three times that of traditional ponds, with a return on investment reaching up to 16.92%. However, the HSD can negatively impact the growth performance, health status, and economic benefit of gibel carp. These results preliminary confirm the feasibility of the LBTAS, highlighting the importance of balanced aquaculture practices for sustainability and profitability.

摘要: Global warming and extreme weather events are exerting significant thermal stress on aquatic species, particularly fish, affecting their metabolism, behavior, immunity, and reproductive strategies. Despite extensive research on the effects of thermal stress on aquatic organisms, there is a gap in understanding how short-term temperature fluctuations influence both behavior and transcriptional dynamics in high-elevation stream fish. We addressed this gap by investigating the effects of temperature variability on the behavior and transcriptomic profiles of Acrossocheilus fasciatus, a commercially valuable, widely distributed, eastern Asian stream fish. We applied two temperature treatments (32 ​°C and 16 ​°C) and two conditions (continuous exposure and temperature recovery) to assess behavioral responses and changes in cortisol and 5-hydroxytryptamine(5-HT) levels. High temperatures increased movement speed and turning angles, whereas low temperatures decreased movement frequency and speed. Low temperatures led to a significant rise in 5-HT, whereas high temperatures caused a decrease. Concurrently, brain transcriptomic analysis identified substantial differential gene expression related to behavioral plasticity and cellular stress responses. Key enriched pathways included circadian rhythm, oxidative phosphorylation, and prolactin signaling, indicating the fish's physiological adaptation to temperature changes. We conclude that high temperatures have a substantial affect on the behavior and transcriptional dynamics of A. fasciatus, including increased aggression and cellular damage, whereas cold temperatures have minimal effects. Fish exposed to temperature recovery conditions demonstrated effective behavioral adaptation. These findings highlight the heightened sensitivity of stream-dwelling fish to thermal extremes and underscore the need for further research on their adaptive mechanisms and long-term effects.

摘要: Antibiotics are widely used in humans, livestock, and aquaculture, but they are not removed fully during wastewater treatment, leading to their accumulation in aquatic environments. This contributes to the spread of antibiotic-resistant bacteria (ARB), posing public health and ecosystem risks. Although antibiotic use has decreased, the transfer of antibiotic resistance genes via integrons among ARB remains a concern. Traditionally, methods such as antibiotic susceptibility testing (AST) and minimum inhibitory concentration (MIC) tests have been used to identify ARBs. However, these methods are limited by their variability, the necessity for time-consuming reculture, and the inability to detect viable but non-culturable (VBNC) bacteria. To overcome such limitations, the ability of propidium monoazide quantitative PCR (PMA-qPCR) to selectively detect only viable bacteria, excluding dead cells, was evaluated. This study assessed ARBs in oyster, sea pineapple, and fish farms along Korea's coast using both conventional AST and MIC tests alongside PMA-qPCR. Vibrio spp., frequently detected at all sites, were used as the target species. PMA-qPCR successfully detected VBNC bacteria that were undetectable in MIC tests, highlighting the potential for VBNC bacteria to be regenerated under favorable conditions and contribute to the spread of resistance genes. The discrepancies between MIC and PMA-qPCR results underscore the need for further development of PMA-qPCR methods to better assess antibiotic resistance and to determine optimal antibiotic dosages.

摘要: Globally, lakes are currently under considerable stress, with endogenous nutrients a critical driver of eutrophication. This study focused on the release of endogenous nutrients and the ecological response mechanisms in degraded shallow lakes, using Honghu Lake as a case study. Ecological surveys and simulation experiments revealed that the average concentrations of total nitrogen, total phosphorus, and organic matter (OM) in the surface sediments of Honghu Lake are 5148.20 ​mg/kg, 688.10 ​mg/kg, and 13.82%, respectively, but varied spatially. The potential diffusion fluxes of NH4⁺-N and PO4^3--P at the sediment-water interface ranged from 0.4471 to 2.1938 mg/(m²·day) (average 1.3130 mg/(m²·day)) and 0.0041–0.0482 mg/(m²·day) (average 0.0237 mg/(m²·day)), respectively. The comprehensive release model indicated that elevated temperature enhanced the release of endogenous nutrients from sediments. At 30 ​°C, the release potentials of total nitrogen and total phosphorus were 3.19 ​± ​0.97 ​g/m² and 0.17 ​± ​0.07 ​g/m², respectively. Annually, the lake sediments released approximately 192.4 tons of NH4⁺-N and 3.37 tons of PO4^3--P, contributing to 79.52% and 5.66% of the needed nitrogen and phosphorus control requirements, respectively. The release of endogenous sediment nutrients played a vital role in influencing the distribution of various aquatic organisms. Notably, the release of endogenous phosphorus significantly affected the distribution of macrobenthos, whereas zooplankton exhibited greater sensitivity to the release of endogenous nitrogen.