Application potential of albendazole as an aquatic animal drug based on its safety, efficacy, and residue profiles.

The number of available drugs for treating aquatic animals is insufficient, given the occurrence of a variety of parasites and difficulties in developing appropriate treatments, such as vaccines or immunostimulants. Consequently, repurposing livestock drugs for treating aquatic animals is a viable alternative. Several studies have demonstrated that albendazole (ABZ) is a good anthelmintic for humans and animals such as ruminants, poultry, and honeybees. Therefore, we investigated the toxicological studies, metabolic and residue depletion studies, and efficacy trials of ABZ in aquatic animals to identify its application potential as a drug for aquatic animals. ABZ was depleted within 24 h in the muscle tissues of hybrid striped bass, rainbow trout, and tilapia. In muscle tissue with adhering skin obtained from tilapia and largemouth bass, a significant quantity of the amino-sulfone metabolite of ABZ (ABZ-SO2NH2) was present, while no ABZ-SO2NH2 was detected in hybrid striped bass, channel catfish, and patinga. Fish exposed only to high doses of ABZ showed reduced red blood cell counts and hemoglobin levels and increased lymphocytes. Such signs of toxicity have also been observed in human patients and animal studies. At a dose of 100 mg/L, ABZ showed 100% efficacy in eels. In addition, albendazole sulfoxide (ABZSO) demonstrated efficacies of 96.1% and 100% in pirapatinga and ray-finned fish, respectively, at a dose 500 mg/L. ABZ was also highly effective in treating an intracellular parasite E. hepatopenaei in white shrimp. The application of ABZ in aquatic animals under the low-dose and short-term conditions is considered a reasonable solution to manage parasite infections. The types and residual periods of degradation products differed among fish species, suggesting dissimilar metabolic pathways. With a high demand for new alternative veterinary drugs in aquaculture by fish farmers, this review offers important evidence for considering the use of ABZ in Korean farmed fish, taking food safety issues into account.

Interactions between lipid metabolism and the microbiome in aquatic organisms: A review.

Marine organisms' lipid metabolism contributes to marine ecosystems by producing a variety of lipid molecules. Historically, research focused on the lipid metabolism of the organisms themselves. Recent microbiome studies, however, have revealed that gut microbial communities influence the amount and type of lipids absorbed by organisms, thereby altering the organism's lipid metabolism. This has highlighted the growing importance of research on gut microbiota. This review highlights mechanisms by which gut microbiota facilitate lipid digestion and diversify the lipid pool in aquatic animals through the accelerated degradation of exogenous lipids and the transformation of lipid molecules. We also assess how environmental factors and pollutants, along with the innovative use of probiotics, interact with the gut microbiome to influence lipid metabolism within the host. We aim to elucidate the complex interactions between lipid metabolism and gut microbiota in aquatic animals by synthesizing current research and identifying knowledge gaps, providing a foundation for future explorations.

Harmful effects of microplastics on respiratory system of aquatic animals: A systematic review and meta-analysis.

The presence of microplastics in the aquatic environment has attracted widespread attention. A large number of studies have assessed the effects of microplastics on the respiratory system of aquatic animals, but the results are not directly comparable across studies due to inconsistent evaluation criteria. Therefore, we adopted an integrated research approach that can integrate and parse complex data to improve reliability, conducted a systematic review and meta-analysis of 35 published studies, and elucidated the mechanisms of microplastic damage to cells. The results showed that PE had the greatest impact on aquatic animals, and fish were the most sensitive to the effects caused by microplastics, with oxidative stress induced by exposure concentrations exceeding 1000 µg/L or exposure times exceeding 28 days, leading to depletion of antioxidant defenses, cellular damage, inflammatory responses, and behavioral abnormalities. As this review is based on existing studies, there may be limitations in terms of literature quality, data availability and timeliness. In conclusion, we suggest to combat microplastic pollution by limiting plastic use, promoting plastic substitution and recycling, and enhancing microplastic capture degradation technologies.

Physical Pretreatments of Cassava Chips Influenced Chemical Composition, Physicochemical Properties, and In Vitro Digestibility in Animal Models.

Physical pretreatment procedures can significantly influence the quality of food and feed raw materials. To increase the ability to be digested in animals, cassava chips were pretreated by four alternative methods (extrusion, microwave irradiation, gamma irradiation, or NaOH hydrolysis), and then the chemical composition, physicochemical properties, and in vitro digestibility of the pretreated samples were assessed and compared with unprocessed cassava chips (control). The chemical compositions (crude protein, ether extract, neutral detergent fiber, acid detergent fiber, ash, non-fiber carbohydrate, and gross energy) were significantly altered due to the pretreatment methods (p < 0.05). The nutritive profile was qualitatively changed when assessed through Fourier-transform infrared spectroscopy. Some physicochemical properties in association with enzymatic hydrolysis, which include pH, water solubility, water absorption capacity, thermal properties (differential scanning calorimetry), diffraction pattern (X-ray diffractometry), and microstructure (scanning electron microscopy), were significantly changed. In vitro carbohydrate digestibility based on digestive enzyme extracts from Nile tilapia (Oreochromis niloticus) suggests the microwaving method for cassava chips preparation, while microwaving, followed by extrusion or gamma irradiation, was suggested for broiler (Gallus gallus domesticus). There were no differences in the pepsin-cellulase digestibility values tested for the ruminant model. These findings suggest the use of pretreated cassava chips in animal feeding.

An easily implemented single-visit survey method for intermittently available and imperfectly detectable wildlife applied to the Florida east coast diamondback terrapin (Malaclemys terrapin tequesta).

Single-visit surveys of plots are often used for estimating the abundance of species of conservation concern. Less-than-perfect availability and detection of individuals can bias estimates if not properly accounted for. We developed field methods and a Bayesian model that accounts for availability and detection bias during single-visit visual plot surveys. We used simulated data to test the accuracy of the method under a realistic range of generating parameters and applied the method to Florida's east coast diamondback terrapin in the Indian River Lagoon system, where they were formerly common but have declined in recent decades. Simulations demonstrated that the method produces unbiased abundance estimates under a wide range of conditions that can be expected to occur in such surveys. Using terrapins as an example we show how to include covariates and random effects to improve estimates and learn about species-habitat relationships. Our method requires only counting individuals during short replicate surveys rather than keeping track of individual identity and is simple to implement in a variety of point count settings when individuals may be temporarily unavailable for observation. We provide examples in R and JAGS for implementing the model and to simulate and evaluate data to validate the application of the method under other study conditions.

Development, validation, and implementation of an ultratrace analysis method for the determination of moenomycin A, in aquatic animal products.

Moenomycin A, an antimicrobial growth promoter widely used as an additive in aquaculture feedstuffs, has been restricted for use in the European Union and China due to its potential risk of promoting resistant strains of pathogenic bacteria and causing residues in aquatic animal products. Although methods for analyzing moenomycin A in feedstuffs have been developed, no established method exists for aquatic matrices. In this study, we present, for the first time, a sensitive and validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of moenomycin A in aquatic animal products. Samples were extracted using methanol and purified with the QuEChERS method employing C18 sorbent. The aliquot was dried under a nitrogen stream, reconstituted with methanol-water solvent, and analyzed by HPLC-MS/MS. The developed method exhibited good linearity (r2 > 0.995) over a wide concentration range (1-100 µg/L) and a low limit of detection (1 µg/kg). Average recoveries ranged between 70 and 110% at spiked concentrations of 1, 50, and 100 µg/kg, with associated intra- and inter-day relative standard deviations of 1.25 to 7.32% (n = 6) and 2.91 to 10.08% (n = 3), for different representative aquatic animal production, respectively. To the best of our knowledge, this is the first reported HPLC-MS/MS method for the quantification of moenomycin A in aquatic animal products. The new approach was effectively employed in the analysis of moenomycin A across various aquatic samples.

Genotype diversity and antibiotic resistance risk in Aeromonas hydrophila in Sichuan, China.

Sichuan is a significant aquaculture province in China, with a total aquaculture output of 1.72 × 106 tons in 2022. One of the most significant microorganisms hurting the Sichuan aquaculture is Aeromonas hydrophila, whose genotype and antibiotic resistance are yet unknown. This study isolated a total of 64 strains of A. hydrophila from various regions during September 2019 to June 2021 within Sichuan province, China. The technique of Multi-Locus Sequence Typing (MLST) was used for the purpose of molecular typing. Meanwhile, identification of antibiotic resistance phenotype and antibiotic resistance gene was performed. The findings of the study revealed that 64 isolates exhibited 29 sequence types (ST) throughout different regions in Sichuan, with 25 of these ST types being newly identified. Notably, the ST251 emerged as the predominant sequence type responsible for the pandemic. The resistance rate of isolated strains to roxithromycin was as high as 98.3%, followed by co-trimoxazole (87.5%), sulfafurazole (87.5%), imipenem (80%), amoxicillin (60%), and clindamycin (57.8%). Fifteen strains of A. hydrophila exhibited resistance to medicines across a minimum of three categories, suggesting the development of multidrug resistance in these isolates. A total of 63 ARGs were detected from the isolates, which mediated a range of antibiotic resistance mechanisms, with deactivation and efflux potentially serving as the primary mechanisms of antibiotic resistance. This study revealed the diversity of A. hydrophila genotypes and the risk of antibiotic resistance in Sichuan, providing reference for scientific and effective control of A. hydrophila infection.

Dynamics of Cardicola spp. Infection in Ranched Southern Bluefin Tuna: First Observation of C. orientalis at Transfer.

Aporocotylid blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for the Southern Bluefin Tuna (Thunnus maccoyii, SBT) industry, where infections can lead to morbidity and mortality in ranched SBT populations. This study compared blood fluke infection in SBT from two companies during the 2021 ranching season. Both companies administered the same dosage of praziquantel approximately 5 weeks after transfer, feeding with frozen baitfish daily; the only difference in the company's practices was that the pontoons were located 2.5 km apart. Infection severity was measured as prevalence and intensity by quantifying adult C. forsteri in SBT heart and copy numbers of C. forsteri and C. orientalis ITS-2 DNA in SBT heart and gills. Data from the 2018 and 2019 harvests of SBT were used to make comparisons with 2021 harvest data. Cardicola orientalis was detected at transfer and no longer detected after treatment with praziquantel. Cardicola spp. were present in 83% of sampled SBT in 2021. Both companies demonstrated similar patterns of infection, and Company A had higher prevalence and intensity of Cardicola spp. infection. Based on C. forsteri ITS-2 DNA, infection intensity at harvest was significantly greater for both companies in 2021 when compared to 2018 and 2019. Continued monitoring of Cardicola spp. in SBT and improvements in diagnostics contribute to our understanding of Cardicola spp. epizootiology and the detection of changes in treatment efficacy.

The aquaculture disease network model (AquaNet-Mod): A simulation model to evaluate disease spread and controls for the salmonid industry in England and Wales.

Infectious disease causes significant mortality in wild and farmed systems, threatening biodiversity, conservation and animal welfare, as well as food security. To mitigate impacts and inform policy, tools such as mathematical models and computer simulations are valuable for predicting the potential spread and impact of disease. This paper describes the development of the Aquaculture Disease Network Model, AquaNet-Mod, and demonstrates its application to evaluating disease epidemics and the efficacy of control, using a Viral Haemorrhagic Septicaemia (VHS) case study. AquaNet-Mod is a data-driven, stochastic, state-transition model. Disease spread can occur via four different mechanisms, i) live fish movement, ii) river based, iii) short distance mechanical and iv) distance independent mechanical. Sites transit between three disease states: susceptible, clinically infected and subclinically infected. Disease spread can be interrupted by the application of disease mitigation measures and controls such as contact tracing, culling, fallowing and surveillance. Results from a VHS case study highlight the potential for VHS to spread to 96% of sites over a 10 year time horizon if no disease controls are applied. Epidemiological impact is significantly reduced when live fish movement restrictions are placed on the most connected sites and further still, when disease controls, representative of current disease control policy in England and Wales, are applied. The importance of specific disease control measures, particularly contact tracing and disease detection rate, are also highlighted. The merit of this model for evaluation of disease spread and the efficacy of controls, in the context of policy, along with potential for further application and development of the model, for example to include economic parameters, is discussed.

Transcription Pattern of Neurotrophic Factors and Their Receptors in Adult Zebrafish Spinal Cord.

In vertebrates, neurotrophins and their receptors play a fundamental role in the central and peripheral nervous systems. Several studies reported that each neurotrophin/receptor signalling pathway can perform various functions during axon development, neuronal growth, and plasticity. Previous investigations in some fish species have identified neurotrophins and their receptors in the spinal cord under physiological conditions and after injuries, highlighting their potential role during regeneration. In our study, for the first time, we used an excellent animal model, the zebrafish (Danio rerio), to compare the mRNA localization patterns of neurotrophins and receptors in the spinal cord. We quantified the levels of mRNA using qPCR, and identified the transcription pattern of each neurotrophin/receptor pathway via in situ hybridization. Our data show that ngf/trka are the most transcribed members in the adult zebrafish spinal cord.

Effect of lipid oxidation on quality attributes and control technologies in dried aquatic animal products: a critical review.

Aquatic animals are viewed as a good source of healthy lipids. Although drying is an effective method for the preservation of aquatic animal products (AAPs), the whole process is accompanied by lipid oxidation. This article reviews the main mechanism of lipid oxidation in the drying process. It also summarizes the effects of lipid oxidation on the quality of dried aquatic animal products (DAAPs), including nutrients, color, flavor, and hazard components, especially for those harmful aldehydes and heterocyclic amines. In addition, it concluded that moderate lipid oxidation contributes to improving the quality of products. Still, excessive lipid oxidation produces hazardous substances and induces health risks. Hence, to obtain high-quality DAAPs, some effective control technologies to promote/prevent lipid oxidation are introduced and deeply discussed, including salting, high-pressure processing, irradiation, non-thermal plasma technology, defatting treatments, antioxidants, and edible coating. A systematic review of the effect of lipid oxidation on quality attributes and control technologies in DAAPs is presented, and some perspectives are made for future research.

Ecosystem sustainability of rice and aquatic animal co-culture systems and a synthesis of its underlying mechanisms.

Integrated planting and breeding of rice and aquatic animals, including traditional rice-fish co-culture (RF), has been conducted for over 1200 years. It is one of the primary modes of modern ecologically sustainable agriculture. Rice and aquatic animal (RA) co-culture systems reduce risks of environmental pollution, reduce greenhouse gas emissions, maintain soil fertility, stabilize grain incomes, and preserve paddy field biodiversity. Nevertheless, the mechanisms that underlie the ecological sustainability of these systems remain controversial and poorly understood, restricting their practice at a larger scale. Here, the latest advance in understanding the evolution and extension of RA systems is synthesized, in addition to a discussion of the underlying ecological mechanisms of taxonomic interactions, complementary nutrient use, and microbially-driven elemental cycling. Specifically, the aim of this review is to provide a theoretical framework for the design of sustainable agricultural systems by integrating traditional knowledge and modern technologies.

Epigenetic analytical approaches in ecotoxicological aquatic research.

Environmental epigenetics has become a key research focus in global climate change studies and environmental pollutant investigations impacting aquatic ecosystems. Specifically, triggered by environmental stress conditions, intergenerational DNA methylation changes contribute to biological adaptive responses and survival of organisms to increase their tolerance towards these conditions. To critically review epigenetic analytical approaches in ecotoxicological aquatic research, we evaluated 78 publications reported over the past five years (2016-2021) that applied these methods to investigate the responses of aquatic organisms to environmental changes and pollution. The results show that DNA methylation appears to be the most robust epigenetic regulatory mark studied in aquatic animals. As such, multiple DNA methylation analysis methods have been developed in aquatic organisms, including enzyme restriction digestion-based and methyl-specific immunoprecipitation methods, and bisulfite (in)dependent sequencing strategies. In contrast, only a handful of aquatic studies, i.e. about 15%, have been focusing on histone variants and post-translational modifications due to the lack of species-specific affinity based immunological reagents, such as specific antibodies for chromatin immunoprecipitation applications. Similarly, ncRNA regulation remains as the least popular method used in the field of environmental epigenetics. Insights into the opportunities and challenges of the DNA methylation and histone variant analysis methods as well as decreasing costs of next generation sequencing approaches suggest that large-scale epigenetic environmental studies in model and non-model organisms will soon become available in the near future. Moreover, antibody-dependent and independent methods, such as mass spectrometry-based methods, can be used as an alternative epigenetic approach to characterize global changes of chromatin histone modifications in future aquatic research. Finally, a systematic guide for DNA methylation and histone variant methods is offered for ecotoxicological aquatic researchers to select the most relevant epigenetic analytical approach in their research.

Research advance in the distribution and ecotoxicological effects of microcystins in aquatic ecosystem.

Cyanotoxins produced by the toxic cyanobacteria is a great threat to global freshwater ecosystems, with hepatotoxic microcystins (MCs) as the most widely distributed and harmful ones. MCs have negative impacts on the structure, function and stability of aquatic ecosystems, posing threats to human health. In this study, we reviewed the distribution of MCs in waterbody, sediments, and different groups of aquatic animals. The toxicity mechanisms of MCs were also reviewed. The ecotoxicological effects of MCs on aquatic animals, aquatic and terrestrial plants, human health risk were summarized. Several biological methods about the prevention and control of MCs were mentioned. Many aspects about MCs that need to be further studied were proposed, aiming to provide a scientific basis for risk assessment and management of MCs.

First Report of Potentially Pathogenic Klebsiella pneumoniae from Serotype K2 in Mollusk Tegillarca granosa and Genetic Diversity of Klebsiella pneumoniae in 14 Species of Edible Aquatic Animals.

Klebsiella pneumoniae can cause serious pneumonitis in humans. The bacterium is also the common causative agent of hospital-acquired multidrug-resistant (MDR) infections. Here we for the first time reported the genetic diversity of K. pneumoniae strains in 14 species of edible aquatic animals sampled in the summer of 2018 and 2019 in Shanghai, China. Virulence-related genes were present in the K. pneumoniae strains (n = 94), including the entB (98.9%), mrkD (85.1%), fimH (50.0%), and ybtA (14.9%) strains. Resistance to sulfamethoxazole-trimethoprim was the most prevalent (52.1%), followed by chloramphenicol (31.9%), and tetracycline (27.7%), among the strains, wherein 34.0% had MDR phenotypes. Meanwhile, most strains were tolerant to heavy metals Cu2+ (96.8%), Cr3+ (96.8%), Zn2+ (91.5%), Pb2+ (89.4%), and Hg2+ (81.9%). Remarkably, a higher abundance of the bacterium was found in bottom-dwelling aquatic animals, among which mollusk Tegillarca granosa contained K. pneumoniae 8-2-5-4 isolate from serotype K2 (ST-2026). Genome features of the potentially pathogenic isolate were characterized. The enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR)−based genome fingerprinting classified the 94 K. pneumoniae strains into 76 ERIC genotypes with 63 singletons, demonstrating considerable genetic diversity in the strains. The findings of this study fill the gap in the risk assessment of K. pneumoniae in edible aquatic animals.

Environmental Factors and Their Threshold Affecting the Survival of Five Aquatic Animal Viruses in Different Animal Cells.

Aquatic animal viruses infect and transmit in aquatic environments, causing serious harm to the aquaculture industry and a variety of wild aquatic animals. How are they affected by environmental factors and do they represent potential threat to mammalian heath or not? Here, the effects of environmental factors (ultraviolet radiation (UV), temperature, pH, and drying) and their threshold on five epidemic aquatic animal viruses infecting amphibians and bony fish, including Rana grylio virus (RGV), Andrias davidianus ranavirus (ADRV), Grass carp reovirus (GCRV), Paralichthys olivaceus rhabdovirus (PORV), and Scophthalmus maximus rhabdovirus (SMRV), were measured and compared in a fish cell line. The examination of virus titers after different treatment in fish cells showed that the two iridoviruses, RGV and ADRV, had a higher tolerance to all of the environmental factors, such as they only had a decay rate of 22-36% when incubated at 37 °C for 7 days. However, the rhabdovirus SMRV was sensitive to all of the factors, with a decay rate of more than 80% in most of the treatments; even a complete inactivation (100%) can be observed after drying treatment. To address the potential threat to mammals, infectivity and limitation factors of the five viruses in Baby hamster kidney fibroblast cells (BHK-21) were tested, which showed that three of the five viruses can replicate at a low temperature, but a high temperature strongly inhibited their infection and none of them could replicate at 37 °C. This study clarified the sensitivity or tolerance of several different types of aquatic animal viruses to the main environmental factors in the aquatic environment and proved that the viruses cannot replicate in mammalian cells at normal physiological temperature.

Environmental DNA study on aquatic ecosystem monitoring and management: Recent advances and prospects.

Environmental DNA (eDNA) is organismal DNA that can be detected in the environment and is derived from cellular material of organisms shed into aquatic or terrestrial environments. It can be sampled and monitored using molecular methods, which is important for the early detection of invasive and native species as well as the discovery of rare and cryptic species. While few reviews have summarized the latest findings on eDNA for most aquatic animal categories in the aquatic ecosystem, especially for aquatic eDNA processing and application. In the present review, we first performed a bibliometric network analysis of eDNA studies on aquatic animals. Subsequently, we summarized the abiotic and biotic factors affecting aquatic eDNA occurrence. We also systematically discussed the relevant experiments and analyses of aquatic eDNA from various aquatic organisms, including fish, molluscans, crustaceans, amphibians, and reptiles. Subsequently, we discussed the major achievements of eDNA application in studies on the aquatic ecosystem and environment. The application of eDNA will provide an entirely new paradigm for biodiversity conservation, environment monitoring, and aquatic species management at a global scale.

Modern biotechnological strategies for vaccine development in aquaculture - Prospects and challenges.

Advances in genomics and the gradual reduction of cost for technologies like whole-genome sequencing have provided exciting opportunities for developing modern biotechnological-based vaccines in aquaculture. This systemic review describes the prospects and challenges of implementing these high-tech vaccines in fish species. The majority of the commercial vaccines in aquaculture utilize conventional procedures for which cost of administration, protective immunity and safety issues are the major challenges. In recent years, more efficient vaccines are being developed by adopting the advances in vaccine technology. Vaccines based on surface antigens, protein/peptide/polysaccharide subunits, recombinant DNA/mRNA/plasmids, novel antigen expression and delivery systems (bacteriophage particles, virus like particles/VLPs, recombinant yeast, mucosal vaccines), novel molecular adjuvants (IL-8, IL-12, HSPs), and encapsulation polymers and polysaccharides like chitosan nanoparticles and PLGA microcapsule were successfully developed. These biotechnology-based vaccines have proved to be very efficient in field trials, but are always in the research pipeline or as patents. Only very few of them are licensed for use, that too, in high-valued fishes like salmonids. Currently, commercial aquaculture vaccines are available for Aeromonas salmonicida, Vibrio salmonicida, Yersinia ruckeri, Vibrio anguillarum, Edwardsiella ictalurid, and for certain Betanodaviruses. Nevertheless, no registered vaccines are available for other major infectious diseases/pathogens such as viral hemorrhagic septicemia virus (VHSV), viral nervous necrosis virus (VNN) and certain other betanodaviruses, channel catfish virus (CCV), gill disease bacteria, mycobacteria, flavobacterium, Edwardsiella tarda, and certain streptococci. Despite the important economic losses that the pathogens cause to aquaculture worldwide, the commercialization of vaccines remains limited due to immunological pitfalls in aquatic species, large-scale vaccination issues, unregulated use of antibiotics and chemicals, gene-based vaccine regulations and commercial viability. If attempts are to be made to develop novel delivery methods, cost-effective procedures, and relaxations in DNA vaccine regulations, biotechnology-based vaccination could circumvent the emerging disease challenges in aquaculture.

Evaluation of establishment and maintenance of primary cell cultures from several strains of common carp (Cyprinus carpio L.).

As a surrogate for the whole organism, primary cultures and cell lines serve as valuable tools for investigating exogenous and endogenous cytopathy. Studying cell responsiveness to diseases and contaminants is considered a less demanding and more readily accessible research approach that minimizes animal distress and provides more specific data. In the current work, the authors established primary cultures from several different organs and tissues of common carp (Cyprinus carpio L.) for subsequent use in other applications. They investigated the technical challenges in obtaining successful and durable carp-derived tissue cultures. The trials indicate that the type of tissue grown, carp strain and fish age impact equally upon culturing success, as do the cultivating conditions. Cells from gill epithelia, head and trunk kidneys, spleen, skin, gonads and ocular tissue were successfully established and maintained for further use in in-vitro testing. The primary cultures were, therefore, used to investigate and assess pathogens and pollutants emerging in carp's environment.