The present study assessed the added diagnostic value of histopathology in complementing molecular detection of World Organization for Animal Health-listed viral pathogens during Colombia's national shrimp health surveillance program. Pooled samples of pleopods from 1,470 whiteleg shrimp Penaeus vannamei (5 animals/pool for a total of 294 pooled samples) were screened for white spot syndrome virus, Taura syndrome virus, and yellow head virus using standardized PCR/reverse transcription PCR assays in accordance with Instituto Colombiano Agropecuario protocols. A subset of 81 shrimp was taken for whole-body histopathology analysis following standardized protocols and a semiquantitative G0-G4 lesion grading scale. Lesions were classified by organ system, and histopathological findings were compared to molecular results. All PCR assays were negative, with internal and external controls performing as expected. Using histopathology, lesions were identified in 77% of the shrimp examined, and lesions were primarily mild. Frequent findings included integumentary and gill colonization by Zoothamnium spp.; hepatopancreatic tubular necrosis with hemocytic granuloma-like reactions compatible with bacterial infection; intranuclear inclusion-like bodies, possibly of parvoviral origin; and focal myofiber necrosis, with organisms consistent with microsporidia. Autolysis was common but did not preclude lesion interpretation. Histopathology provided diagnostic information that was not captured by targeted molecular assays, revealing subclinical, opportunistic, and nonviral processes relevant to shrimp health. Incorporating histopathology into routine surveillance programs enhances pathogen detection and strengthens health assessments to certify disease-free status of shrimp production systems, as recommended by the World Organization for Animal Health. Integrating histopathology with PCR improved shrimp health surveillance by detecting lesions and opportunistic pathogens not captured by molecular tests alone, providing a more comprehensive overview of shrimp health in Colombian farms.
In recent years, the residue of psychotropic drugs such as diazepam in aquatic products has attracted widespread attention and is one of the important hidden dangers to the quality and safety of agricultural products. This study developed a modified QuEChERS method combined with UPLC-MS/MS to determine the residues of diazepam and its active metabolites, nordiazepam, oxazepam, and temazepam, in aquatic products and aquaculture environments. The important variables of the QuEChERS procedure were screened and optimized through single-factor experiments and response surface methodology. The recoveries of analytes in five aquatic products, pond water, and sediment were 87.4-97.8%, 90.4-96.4%, and 85.2-94.7%, respectively, with relative standard deviations of less than 15%. The limits of quantification were 0.1 μg kg-1 for the four analytes in aquatic products and sediments, and 5 ng L-1 in pond water. This method has been successfully applied to the analysis of diazepam and its active metabolite residues in 28 freshwater aquaculture farms in South China. The detected concentrations of the four analytes in aquatic products, sediments and pond water were 0.18-3.03 μg kg-1, 0.21-17.5 μg kg-1 and 5.56-391 ng L-1, respectively. The illegal abuse of diazepam in fishing bait may be an important source of pollution in aquatic products. The risk assessment results showed that the residues of diazepam in aquaculture posed an acceptable risk to human health and a medium risk to the ecosystem. These results confirmed that the established method is suitable for the simultaneous analysis of diazepam and its active metabolites in aquatic products and aquaculture environments.
The Blue Catfish Ictalurus furcatus is commonly raised in warmwater aquaculture in the United States to produce Channel Catfish I. punctatus × Blue Catfish hybrids. It is also a prominent aquatic invasive species of concern in the mid-Atlantic region of the United States. Here, Yersina ruckeri was isolated from moribund Blue Catfish and hybrid catfish from disparate regions of the USA. The goal of the research here was to compare these Y. ruckeri strains to each other and other known strains for which adequate sequence data was available. In addition, we sought to determine if the strain from Blue Catfish was pathogenic to Rainbow Trout Oncorhynchus mykiss. Moribund hybrid catfish from culture ponds in Mississippi were processed for diagnostic evaluation in March 2016. In April 2022, a moribund Blue Catfish specimen was collected from a tributary of the Nanticoke River in Maryland. Bacterial isolates were identified and characterized using biochemical tests, antimicrobial sensitivity screening, serotyping, and complete or partial genome sequencing. Disease pathology was described via histology. The isolate from Blue Catfish was used in challenge experiments to determine if it was pathogenic to Rainbow Trout. Multilocus sequencing typing was conducted using the PubMLST database. Biochemical testing was consistent with Y. ruckeri. A draft genome of the Y. ruckeri isolate was assembled based on Oxford Nanopore Technology sequencing and identified a single genomic replicon (3,791,418 bp) consistent in size to other Y. ruckeri genomes and a pLT plasmid (60, 933 bp). The challenge study demonstrated no significant virulence of this isolate for Rainbow Trout (Y. ruckeri). This isolate was most similar to other strains isolated from ictalurids. Notably, the gyrase B gene from this isolate was identical to that of archived strains isolated from moribund Mississippi hybrid catfish aquaculture during 2016 and these isolates share identical PubMLST sequence type profiles. Similarly, they shared a pLT plasmid that differed by only 6 bp. This plasmid has never been reported from trout isolates and appears to be unique to ictalurids. Analyses here provide preliminary genetic evidence that geographically distant (Maryland and Mississippi, USA) isolates of Y. ruckeri from ictalurids are genetically similar to each other and Y. ruckeri (strain SC09) that infects ictalurids in China. This strain is not a biothreat to Rainbow Trout at typical culture temperatures. Blue Catfish were introduced into lower Chesapeake Bay tributaries in the 1970s, and their range has since expanded into the north throughout the Chesapeake Bay watershed. The success and spread of this invasive species has raised concerns over their effect on native fish populations, including competition for food, predation, and the spread of infectious disease. Blue Catfish are also used to establish hybrid catfish as part of commercial aquaculture practices in the southeastern United States. The report here documents the identification and characterization separate cases of yersiniosis, a disease caused by the bacterium Yersinia ruckeri, in a wild Blue Catfish from the northeastern USA and cultured hybrid catfish in the southeastern USA. Yersiniosis is a serious disease affecting both wild and farmed fish. This research demonstrates that this strain of the bacterium is not geographically restricted and that wild Blue Catfish could be a source of Y. ruckeri infection in catfish production ponds. While this strain of the bacterium clearly causes disease in catfishes, it does not appear to be a threat to Rainbow Trout.
Food consumption patterns are significant drivers of environmental burdens, prompting increasing interest in dietary transitions. The possibility of adjusting animal-based dietary patterns with different consumption compositions, and the consequent large environmental implications considering the evolution of society and ecosystems in different shared socioeconomic pathways (SSPs), however, have rarely been quantified. Furthermore, their connections with sustainable development goals (SDGs) require clearer elucidation. Taking into account the various eating habits among different groups of people in different regions, we systematically quantified the future consumption of animal-based foods with and without a dietary transition to the healthy pattern and their environmental footprints in China under SSPs 1-5 in 2030 and 2060. Historically, meat consumption in China, dominated by pork, exceeded 66.48% of the recommendations for a healthy dietary pattern. The shift in dietary patterns would greatly increase the demand for aquatic products in the future, reaching a maximum of 1445.61 × 104 t in SSP3 by 2060 (87.36%). The animal-based dietary transition to recommendations would embody environmental benefits by reducing the footprints of carbon, water, land, and nitrogen (by 3.80-10.45%, 5.84-14.46%, 15.83-23.18%, and 0.75-9.49%, respectively) in SSPs in China. A dietary transition would also benefit achieving SDGs from natural and socioeconomic aspects, like SDGs 2 (Zero hunger), 3 (Good health and well-being), 13 (Climate action), and 15 (Life on land). Dietary transitions to more aquatic products offer a promising pathway to sustainably nourish the growing population while limiting damage to the planet's integrity. © 2025 Society of Chemical Industry.
Pyrimidine has a broad range of biological actions and may be an eco-friendly substitute for health management. To explore bioefficiency in fish, different concentrations (10 fg/mL to 1 mg/mL) of a pyrimidine analog (4,6-dimethyl-2-hydroxypyrimidine hydrochloride) were prepared from stock solution in water with Stinging Catfish Heteropneustes fossilis for 24 h to determine the effective concentration based on hematological parameters. The effective concentration of pyrimidine (10 pg/mL) was further examined for a study of duration effects (1, 5, and 21 d), followed by a 1-week recovery period (in only water). The pyrimidine analog improved health-supportive hematological parameters and moderated antioxidative stress. Pyrimidine treatment significantly increased red blood cell count and hemoglobin in Stinging Catfish. It also significantly decreased the white blood cell count, myeloperoxidase activity, and nitroblue tetrazolium in a time-dependent manner, thus helping to manage stress. Nutrient levels (protein, carbohydrate, and lipid) also were improved in pyrimidine-treated fish compared to control fish without treatment. Results supported the stimulatory effect of pyrimidine on fish immunity, nutrient level, and health parameters. During the recovery period, the levels of the analyzed parameters remained close to those measured at 21 d of treatment compared to the control fish. A reduction in health-supportive parameters 1 week after pyrimidine treatment supported the metabolized nature of the pyrimidine analog compared to other contemporary bioaccumulative drugs. There was no side effect of the effective concentration of the pyrimidine analog, and it did not cause any change in body weight and growth after treatment. This study suggests that a pyrimidine analog (4,6-dimethyl-2-hydroxypyrimidine hydrochloride) significantly improves the health parameters of Stinging Catfish in a duration-dependent manner. Results indicated overall health improvement (regulating nutrient, stress, and immunity parameters) after pyrimidine treatment without any adverse effects, and pyrimidine was further cleared from the biological system.
This study presents the development and validation of a Health Index (HI) to assess the overall health of stranded marine tetrapods (seabirds, sea turtles, and marine mammals). The HI is based on parameters collected during necropsies and histopathological analyses, including body condition, systemic conditions (macroscopic and by histopathology), cutaneous injuries, organized lesions, parasitosis, lymphoid depletion, and thyroid alterations. The HI was applied to data from 6,332 marine tetrapods stranded along the Brazilian coast. Results showed that the HI effectively differentiated between animals with good, fair, and poor health, as evaluated by independent veterinary assessments. Sea turtles exhibited the lowest average HI, suggesting poorer health conditions compared to seabirds and marine mammals. The HI has proven to be a valuable tool for monitoring the health of marine tetrapod populations. Using a quantitative measure of an animal's health enables the evaluation of spatial and temporal variations in health status and the identification of more subtle impacts on species or populations. Thus, the HI allows for an objective assessment and comparison of wildlife health, supporting conservation efforts and helping to identify potential threats.
This study evaluated the effect of commercial Bacillus spp. probiotics on growth performance, immunity, gut microbiota composition, and disease resistance to Vibrio parahaemolyticus in Pacific white shrimp Litopenaeus vannamei that were reared under biofloc conditions. A 56-d feeding trial was conducted in a static biofloc system with postlarval shrimp (1.00 ± 0.03 g). A total of 1,080 shrimp were randomly assigned to three groups: two treatment levels (recommended dose [PRO × 1] and a doubled dose [PRO × 2]) of a commercial probiotic blend, PRO4000X, alongside a control group (CTL; no probiotics). At the trial end point, hepatopancreas and gut samples were collected for gene expression. Gut samples were also obtained for gut microbiota analysis via 16S ribosomal RNA sequencing, and hemolymph samples were withdrawn to measure the total hemocyte count. Probiotic applications did not significantly affect growth performance, including final biomass, mean weight, survival, and feed conversion ratio under the experimental conditions. The probiotic-treated shrimp exhibited enhanced survival during a V. parahaemolyticus (strain A3) challenge, with significantly lower mortality rates (P < 0.001; 42.5 ± 4.3% for PRO × 1 and 60 ± 6.5% for PRO × 2) relative to the CTL (100 ± 0.00%). Immune parameters, such as total hemocyte count, did not differ. Interestingly, the expression of the antioxidant gene sod (superoxide dismutase) in the shrimp gut was significantly downregulated in the PRO × 1 group relative to the control (P = 0.030), which suggests reduced oxidative stress under probiotic supplementation. The analysis of the gut microbiota revealed differences in alpha diversity, specifically in evenness and Shannon index, which were significantly higher in the PRO × 1 group. The analysis of the bacterial composition also revealed minor shifts in the dominant genera. Notably, Lysobacter was more abundant in the PRO × 1 group, which potentially reflects positive modulation of gut microbial communities in response to probiotic supplementation. Overall, the application of PRO4000X probiotics significantly reduced the V. parahaemolyticus infection in the shrimp that were reared in biofloc water and supported the regulation of immunity and microbial communities in the gut. These findings indicate that probiotics potentially help to improve shrimp health when shrimp are cultured in biofloc systems. With the growing demand for shrimp, shrimp farming has been expanding rapidly. However, the risk of disease outbreaks, especially Vibrio parahaemolyticus infections, remains a major concern. This study demonstrated that after 56 d, the commercial probiotic PRO4000X enhanced immune responses, improved gut microbiota, and contributed to better disease resistance in shrimp.
This study engaged representative native freshwater mussel propagation biologists in focus group discussions to learn their views and priorities related to the development and adoption of freshwater mussel health metrics. It provides a case study on how early consultation with practitioners can better inform research questions and improve imperiled species conservation. Two focus group discussions were conducted with freshwater mussel propagation biologists from across the United States to understand the needs of conducting mussel health assessments, current approaches, technical capacity, and where advances may be most beneficial. Propagation biologists identified how they currently measure freshwater mussel health, listed the largest threats to health, explained similarities among approaches, and made recommendations for future research. Propagation biologists called for quantitative metrics that complement current procedures that could be measured nonlethally and were reflective of health and resilience rather than presence or absence of disease. Further conservation research could benefit from early engagement with propagation biologists to better ensure adoption of research products and tools. This study explored the challenges and needs of assessing the health of freshwater mussels, a group of highly imperiled species. We conducted focus group discussions with mussel propagation biologists who highlighted the need for standardized health metrics to avoid health declines.
Methyl parathion, a potent organophosphorus insecticide, is extensively employed in agriculture and animal husbandry, leading to significant environmental contamination with pesticide residues, posing a grave threat to human health. This compound irreversibly inhibits acetylcholinesterase (AChE) in the human nervous system, resulting in the accumulation of acetylcholine (ACh), which is detrimental. Various enzyme activity-based assays have been explored due to its pathogenic mechanism, yet these methods are fraught with limitations. Thus, the development of a highly selective, sensitive, rapid, and effective method for detecting methyl parathion residues is crucial. In this study, we introduce a novel, non-enzymatic fluorescent probe for methyl parathion detection. This probe is designed to specifically trigger the fluorescence signal of TAPB-DMTA-COF through the interaction of copper ions with the imine moiety within the TAPB-DMTA-COF structure. The detection of methyl parathion in aqueous environments is facilitated by the Inner filter effect. Compared to previously reported enzyme-catalyzed reaction probes, this probe exhibits a faster reaction time, is not influenced by enzyme activity, and demonstrates high specificity and sensitivity. The probe exhibits a good linear response in the concentration range of 0.56-5.46 μM, with a detection limit of 30.698 nM. Furthermore, the probe yielded satisfactory recoveries of methyl parathion (93.47 %-99.5 %) in different real water samples through spiking recovery experiments. The fluorescent probe based on Cu2+/TAPB-DMTA-COF realizes the fluorescence detection of methyl parathion. The establishment of this simple, efficient, and rapid detection platform offers a new approach for the detection of pesticide residues in aquatic environments. The introduction of metal ions, along with the construction of COF materials and the use of fluorescence signal turn-on, provides a rational design strategy for such detection methods.
Albendazole is a commonly-used antiparasitic drug that has been extensively applied in animal husbandry and aquaculture to prevent and treat various parasitic infections. However, the potential residues of albendazole in animal-derived foods and the aquatic environment can pose risks to human health and ecological balance. Hence, the development of a highly sensitive and rapid analytical method for albendazole is of utmost importance to safeguard food safety and preserve the ecological environment. MXene nanosheets (Ti3C2Tx) are emerging as promising precursors for the design of such detection systems. (86) RESULTS: In this work, MXene nanosheets (Ti3C2Tx) were alkalized in NaOH solution to form alkalized Ti3C2Tx (Al-MXene). The treatment caused structural changes such as expanded interlayer spacing, reduced particle size, enhanced Zeta potential, and the formation of amorphous TiO2 on the surface. These modifications gave Al-MXene larger electrochemical active specific area and stronger physical adsorption capacity for albendazole compared to the original MXene nanosheets. When Al-MXene was decorated on the surface of laser-induced graphene (LIG), albendazole was efficiently oxidized due to the unique surface activity of Al-MXene and the abundant three-dimensional porous structure of LIG. An integrated three-electrode device based on the Al-MXene/LIG structure was fabricated for the electrochemical detection of albendazole in micro-droplets for milk sample. The device showed a linear detection range from 10 nM to 1 μM, a sensitivity of 411 μA μmoL-1 cm-2, and a detection limit of 7.5 nM (143) SIGNIFICANCE: The development of the integrated three-electrode device based on Al-MXene/LIG provides a highly sensitive and efficient method for detecting albendazole in milk samples. Moreover, it can also offer guidance for fabricating more innovative electrochemical sensors for the rapid screening of veterinary drug residues. This contribution is of great significance in ensuring food safety and protecting public health. (57).
Zoonotic diseases pose a significant risk to human health globally. The interrelationship between humans, animals, and the environment plays a key role in the transmission of zoonotic infections. Human-animal contact (HAC) is particularly important in this relationship, where it serves as the pivotal interaction for pathogen spillover to occur from an animal reservoir to a human. In the context of disease emergence linked to land-use change, increased HAC as a result of land changes (e.g., deforestation, agricultural expansion, habitat degradation) is frequently cited as a key mechanism. We propose to conduct a systematic literature review to map and assess the quality of current evidence linking changes in HAC to zoonotic disease emergence as a result of land-use change. We developed a search protocol to be conducted in eight (8) databases: Medline, Embase, Global Health, Web of Science, Scopus, AGRIS, Africa-Wide Info, and Global Index Medicus. The review will follow standard systematic review methods and will be reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. The search will consist of building a search strategy, database search, and a snowballing search of references from retrieved relevant articles. The search strategy will be developed for Medline (through PubMed) and EMBASE databases. The search strategy will then be applied to all eight (8) databases. Retrieved articles will be exported to EndNote 20 where duplicates will be removed and exported to Rayyan®, to screen papers using their title and abstract. Screening will be conducted by two independent reviewers and data extraction will be performed using a data extraction form. Articles retrieved will be assessed using study quality appraisal tools (OHAT-Office for Health Assessment and Technology Risk of Bias Rating Tool for Human and Animal Studies, CCS-Case Control Studies, OCCSS-Observational Cohort and Cross-Sectional Studies, and CIS-Controlled interventional studies). Data will be analysed using descriptive statistics and a meta-analysis where data permits. The review will provide an important systematic literature aggregate of existing evidence on the role and evidence quality linking HAC to the emergence of zoonoses via land-use change. The outcome of the proposed review will produce a high-level evidence document that could inform intervention points and further research priorities. The review will be registered with PROSPERO.
This study aimed to characterize the effects of Prochristianella sp. infection (Cestoda: Trypanorhyncha) in the Octopus maya, with focus on tissue pathology, immune response, and potential implications for host health. Molecular analyses of 28S ribosomal DNA were performed to confirm the identity of collected parasites from the buccal mass of octopus hosts. Macro- and microscopic observations of O. maya tissues, hemocyte counts, and histological analyses were conducted to assess the damage caused by the infection. Comparisons were made between naturally infected octopuses from Río Lagartos, Yucatán (the affected group), and minimally infected octopuses from Campeche (the control group) to establish a reference baseline for health and tissue morphology. Prochristianella sp. 1 was the only parasitic species infecting the buccal mass of octopuses collected from Río Lagartos, contrasting with the absence of the parasite in octopuses from Campeche, which were used as a reference group to characterize the infection. The affected group exhibited an undescribed capsular structure on the superior mandibular muscle of the buccal mass, containing cestodes and mucus and associated with tissue alterations, such as fibrosis, hemocyte infiltration, and focal necrosis. These findings led to the provisional designation of this condition as "myocestodiasis in cephalopods." This work provides new findings on helminth-induced pathologies, generating hypotheses about the underlying mechanisms in infected cephalopods. The study highlights the importance of multidisciplinary approaches to understanding host-parasite interactions. Furthermore, it lays the groundwork for managing and conserving the O. maya, an important marine resource of the Yucatán Peninsula. This study describes a new parasite-caused disease in octopuses, revealing how these infections affect octopus health and highlighting the importance of understanding diseases in marine animals.
To address the issues of operational complexity, long duration association, and reliance on specialized equipment with existing detection methods for Vibrio parahaemolyticus, this study established a rapid detection method for V. parahaemolyticus in exported aquatic products based on the domestically developed Enzymatic Recombinase Amplification (ERA) technology. To target the thermolabile hemolysin gene (tlh) and the iron-regulated virulence regulatory protein gene (irgB) of V. parahaemolyticus, highly specific ERA primers and probes were designed and screened. Two detection platforms, a colorimetric method and a fluorescent method, were developed. Method validation results showed that this detection system achieved specific amplification for all 30 tested V. parahaemolyticus strains, with no cross-reactivity observed with 30 other common foodborne pathogenic bacteria. The detection sensitivity for both the fluorescent and colorimetric methods reached 10-1 ng/μL, with a minimum detection limit of 10 CFU/25 g for artificially contaminated samples. The entire detection process, including sample preparation, requires only approximately 20 min-significantly faster than traditional culture (24-72 h) or even conventional PCR methods. Collaborative validation across five independent laboratories confirmed excellent reproducibility, with inter-laboratory agreement yielding a Kappa coefficient of 0.98. The ERA method operates at a low, constant temperature (37-39 °C), eliminating the need for thermal cyclers. When combined with portable isothermal amplification devices and visual (colorimetric) readout, it offers a distinct advantage in terms of speed, cost-effectiveness, and suitability for resource-limited or field settings compared to existing PCR-based or culture-based platforms. This method is simple to operate, rapid, sensitive, and highly suitable for on-site application, providing a reliable and practical technical solution for the rapid screening and risk monitoring of V. parahaemolyticus in exported aquatic products.
The present study examined the effect of humic substance and butyric acid blend (HSB) supplementation, with and without yeast cell wall (YCW), on gut morphology, immunity, and resistance to Flavobacterium covae, Edwardsiella ictaluri, and their coinfection in juvenile Channel Catfish Ictalurus punctatus. A feeding trial was conducted in a recirculating aquaculture system with Channel Catfish fingerlings (19.7 ± 0.2 g). Thirty-seven Channel Catfish were randomly assigned into four dietary groups with supplemented feed (g/kg): HSB (2.0 HSB), YCW (0.5 YCW), HSB + YCW (1.0 HSB, 0.25 YCW), and a control group (not supplemented), each consisting of eight replicates. After 45 d of feeding the diets, growth performance was assessed and head kidney, spleen, and gill tissues were sampled for gene expression, while serum was collected for lysozyme activity. Subsequently, fish were pooled by treatment and challenged by immersion with either E. ictaluri (S97-773; 7.4 × 106 CFU/mL), F. covae (ALG-00-530; 1.2 × 106 CFU/mL), or coinfection with simultaneous half-doses of both bacteria. No significant differences were observed in fish growth performance and survival across treatments. However, Fulton's K-factor was significantly higher in the HSB group compared with the control. Serum lysozyme activity was significantly higher in the HSB group, while a numerically higher body mucus lysozyme activity was observed in the HSB + YCW group. No diet-related cytokine gene expression differences were observed in the kidney and splenic tissues. However, differences were observed in the expression of lysozyme genes lysc and lysg in the gill, with the highest expression in the YCW group. Furthermore, expression of ctsd (cellular protease) and defb (antimicrobial peptide) were different across all groups. Specifically, ctsd was upregulated in the HSB group when compared with the control. The expression of defb was upregulated in all treated groups, including HSB, YCW, and HSB + YCW, compared with the control group. After a 14-d bacterial challenge with either F. covae, E. ictaluri, or simultaneous exposure to both, significant differences in survival probabilities were observed across the treatment groups in the single E. ictaluri and coinfection groups but not in the F. covae group. Survival following E. ictaluri challenge varied among groups, with higher survival observed in the HSB group (79%) compared with the control fish (52%). Similarly, the HSB group showed improved survival (72%) compared with YCW (30%), HSB + YCW (45%), and the control group (30%) within the coinfected groups. Furthermore, the survival rate of Channel Catfish was lower in the coinfected groups than in those solely infected with E. ictaluri. Feeding Channel Catfish with a dietary humic substance and buryate blend reduced the susceptibility of Channel Catfish to E. ictaluri and coinfection with F. covae. These research findings have potential practical implications for fish health and provide an alternative tool for the management of coinfections in the catfish industry. Diseases affecting catfish reared in ponds often result from the interaction of multiple bacteria, causing increased fish loss and treatment difficulties. This study demonstrated that feeding of Channel Catfish with a humic substance and butyrate blend in the diet for 45 d resulted in higher antimicrobial activity and resistance to common bacterial diseases affecting the catfish industry.
The objective of this study was to evaluate the potential influence of skeletal muscle mercury (Hg) concentrations on the biometric parameters and the frequency of lesions in Smallmouth Bass Micropterus dolomieu that were captured from three streams in Great Smoky Mountains National Park. By investigating the correlations between lesions, parasitism, and Hg concentrations, this study details the potential sublethal Hg contamination in fish in protected stream ecosystems. Postmortem examinations with comprehensive histopathological analysis were performed on Smallmouth Bass (n = 62) that were collected from three streams in Great Smoky Mountains National Park, Abrams Creek (nAC = 27), Little River (nLR = 19), and Middle Prong Little Pigeon River (nMP = 16), from June to October 2022. Postmortem and histopathological data were matched to existing data on the concentrations of Hg in skeletal muscle to determine relationships between Hg concentration and pathology. Smallmouth Bass from Abrams Creek had higher total Hg concentrations, higher proportions of gill lesions, lymphohistiocytic epicarditis, and increased percentages of splenic pigmented macrophage aggregates but lower proportions of myxozoan cysts relative to the fish from other streams. Smallmouth Bass with high concentrations of Hg exhibited increased total length and body mass and more frequently showed the presence of glycogen-like vacuolation and increased pigmented macrophage aggregates in kidney tissue. Myxozoan cysts were more common in fish with lower total Hg levels, signifying the possible role of environmental impacts on myxozoan infection pressure. These findings highlight the complex health profiles of Smallmouth Bass in a protected stream ecosystem, including high levels of Hg, parasitism, and lesions. Furthermore, this study underscores the importance of monitoring and mitigating heavy metal contaminants to safeguard wildlife health and recreational fishing resources. Smallmouth Bass from three streams demonstrated that mercury accumulation was higher in larger fish, indicating bioaccumulation. Also, fish with lower levels of mercury were more likely to have certain parasites, suggesting that environmental mercury may affect the health and abundance of parasites and intermediate hosts.
Vibrio parahaemolyticus is a major cause of seafood-associated gastroenteritis and aquatic animal diseases, posing persistent threats to public health and aquaculture. Rapid and accurate on-site quantitative detection is essential for risk assessment and early intervention. Although qPCR and digital PCR provide reliable quantification, their reliance on complex instrumentation limits field deployment. RPA-CRISPR-based isothermal assays offer a low-equipment alternative; however, existing approaches lack robust methodological strategies to achieve standard-curve-based quantitative reliability under field-deployable conditions. Here, we propose a methodological framework that enables in-run calibration and variance control for quantitative isothermal amplification by integrating reaction-volume locking and simultaneous standard-curve generation, implemented here within a closed centrifugal microfluidic system. A multi-unit microfluidic platform preloaded with gradient concentration standard plasmids allows concurrent construction of standard curves and sample analysis in a single run, reducing the impact of environmental and batch-to-batch variability. Signal generation was achieved using a one-pot RPA-CRISPR/Cas12a assay, in which balanced amplification and cleavage kinetics were obtained by screening crRNAs targeting suboptimal PAM sites and optimizing reaction conditions. The platform achieved a detection limit of 6.08 copies/μL and a linear quantitative range of 100-104 copies/μL (R2 > 0.96), with performance comparable to qPCR (AUC = 0.984), and acceptable intra- and inter-assay variability under the tested conditions, with relative standard deviations of 2.63-6.07 %, at a cost of approximately $3.30 per test. Validation using spiked and real seafood samples demonstrated reliable on-site quantification. This work establishes a transferable quantitative methodology for RPA-CRISPR-based isothermal assays, advancing field-deployable pathogen detection in aquaculture and food safety.
Anthropogenic activities exert significant pressures on the dynamics and health of dominant fish species in aquatic ecosystems. In this study, we evaluated how human activities impact the community structure, length-weight relationships, and condition factors of key fish species in a north-central Nigeria river. Sampling was conducted over 14 months across four sites with varying levels of disturbance: Zhabyala (minimal), Tunga Waya, Chanchaga, and Korokpan (severe). A total of 1361 fish individuals, representing diverse orders and families, were collected. Dominant species such as Tilapia zillii and Tilapia guineensis featured prominently in our analysis. Site 1 exhibited the highest abundance (n = 594), while site 4 had the lowest (n = 238). Characiformes dominated the assemblage, followed by Cypriniformes and Mormyriformes. Correlation analysis highlighted strong associations between environmental factors and the length-weight relationships of dominant species. Tilapia zillii showed the highest mean standard length and body weight at site 1, whereas Tilapia guineensis demonstrated the highest standard length at site 1 and the greatest body weight at site 3. Despite favorable health indicators for many dominant species, environmental stress was evident at specific sites. This study provides crucial insights into the condition factors and ecological dynamics of dominant fish species, serving as a valuable reference for future conservation and management efforts.
<p>Introduction: Given the lack of effective pharmacotherapy for vascular dementia (VaD) and the reported benefits of exercise, this study examined the impact of water temperature during aquatic exercise (AE) on cognitive and pathological outcomes in a mouse model of VaD. Twelve-month-old male mice underwent bilateral common carotid artery stenosis (BCAS) to induce chronic cerebral hypoperfusion. Groups included sham, BCAS control (no exercise), and BCAS mice assigned to AE in water baths at 25°C, 30°C, or 35°C. Cognitive performance was assessed using the elevated plus maze, Y-maze, and novel object recognition test (NORT). Brain tissues were analyzed for microglial marker CD68, astrocytic marker GFAP, and myelin basic protein (MBP) in the corpus callosum. The 30°C AE group showed the greatest improvement in NORT performance and swim activity. CD68 expression was unchanged across groups, but GFAP expression was significantly reduced at 30°C, suggesting suppressed astrocyte activation. Furthermore, the decline in MBP expression after BCAS was attenuated in this group, indicating preserved white matter integrity. AE at approximately 30°C alleviated cognitive deficits in a VaD model, likely by reducing neuroinflammation and protecting myelin. These findings highlight the therapeutic potential of optimizing AE conditions, particularly water temperature, for dementia-related rehabilitation. </p>.
In aquaculture, the trend is shifting towards using plant-derived alternatives that are abundant in phytochemicals as effective replacements for traditional antibiotics and synthetic feed additives. In the present study, the effects of tulsi Ocimum sanctum extract on growth performance, hemato-biochemical indices, serum immune parameters, and antioxidant parameters in Common Carp Cyprinus carpio were investigated. Common Carp (mean body weight ± SD = 10.6 ± 0.13 g) were fed experimental diets that contained tulsi leaf extract at 0.0 (control), 0.5, 1.0, and 1.5% for 60 d (25 fish/treatment). The findings revealed a considerable enhancement in growth performance and a decreased feed conversion ratio, especially for the 1.0% tulsi-based diet. Additionally, weight gain and feed conversion ratio exhibited significance at both the linear and quadratic levels, as indicated by polynomial contrasts. The hematological and biochemical profiles exhibited improvements in groups receiving tulsi-enriched diets. The antioxidant status of fish serum exhibited a notable increase, as evidenced by elevated activities of total antioxidant capacity, superoxide dismutase, and catalase in fish that received the 1.0% and 1.5% tulsi-based diets. Tulsi-supplemented diets led to remarkable enhancements in serum lysozyme activity, alternative complement activity, and total immunoglobulin content. Moreover, tulsi supplementation at 1.0% and 1.5% showcased a significant reduction in serum glucose and cortisol levels compared to the other groups. In conclusion, tulsi extract emerged as a valuable asset, positively influencing growth, blood parameters, antioxidant balance, and serum immune response in Common Carp, particularly at supplementation levels ranging from 1.0% to 1.5% in the diet. This research provides compelling evidence of the remarkable benefits of tulsi extract in Common Carp aquaculture. By enhancing growth performance, feed conversion efficiency, and key hematological and biochemical parameters, tulsi emerges as a powerful natural supplement. Additionally, its significant role in boosting antioxidant status and immune responses further underscores its potential in promoting overall fish health. These findings open new avenues for sustainable and natural approaches in aquaculture, reinforcing the value of tulsi as a functional feed additive.
We sought to establish a current understanding of the histopathology of bivalves following exposure to heavy metal and to standardize the related terminology and microscopic diagnostic techniques, highlight limitations that hinder understanding, and discuss future research perspectives. We conducted a literature review, looking for studies that implemented histopathological analyses to describe the damage that is caused by heavy metal bioaccumulation. For further description, we categorized lesions as regressive, defensive, or progressive. We analyzed 49 articles that employed histopathological techniques to describe the morphological changes that are associated with heavy metal bioaccumulation in bivalves. Since the 1980s, a growing interest in understanding how heavy metals affect bivalves has been evident, given the increasing number of published articles. Most studies were descriptive, although some contained experimental methods. The descriptive studies described damage to the digestive gland, gonads, gills, and kidneys. Defensive lesions were the most common response in the literature, with inflammation events reported in most cases. Regressive and progressive lesions were also documented, with necrosis (regressive change) and fibrosis (progressive change) being the most commonly reported, although not always correctly identified using microscopy. Histopathological studies on the effects of heavy metals on bivalve health are abundant, and the resulting morphologic lesions have been described extensively. However, most studies on heavy metal accumulation in bivalves have not followed a microscopic approach, focusing instead on using bivalves solely as sentinel or bioindicator species. A histopathologic evaluation is a common and important facet of pathologic analyses; however, we identified inconsistencies among diagnoses and misleading use of pathological terms. Therefore, we highlight the need to establish a systematic and standardized characterization of lesions at the microscopical level and their subsequent categorization to reduce the ambiguity of pathological descriptions. Implementing other methodological approaches in combination with histopathological analysis will improve our understanding of how heavy metals affect the health of bivalves. Scientists who are trained in histopathology are needed to improve our understanding of bivalve biology and the damage that heavy metals cause in these organisms. We propose a systematic approach to categorizing morphological changes and standardizing terms to avoid ambiguity in diagnoses.