ITGB1b-Deficient Rare Minnows Delay Grass Carp Reovirus (GCRV) Entry and Attenuate GCRV-Triggered Apoptosis

Silver Nanoparticles Exposure Impairs Cardiac Development by Suppressing the Focal Adhesion Pathway in Zebrafish

Introduction

The potential toxic effects of wastewater discharges containing silver nanoparticles (AgNPs) and their release into aquatic ecosystems on aquatic organisms are becoming a major concern for environmental and human health. However, the potential risks of AgNPs to aquatic organisms, especially for cardiac development by Focal adhesion pathway, are still poorly understood.

Methods

The cardiac development of various concentrations of AgNPs in zebrafish were examined using stereoscopic microscope. The expression levels of cardiac development-related genes were analyzed by qRT-PCR and Whole-mount in situ hybridization (WISH). In addition, Illumina high-throughput global transcriptome analysis was performed to explore the potential signaling pathway involved in the treatment of zebrafish embryos by AgNPs after 72 h.

Results

We systematically investigated the cardiac developing toxicity of AgNPs on the embryos of zebrafish. The results demonstrated that 2 or 4 mg/L AgNPs exposure induces cardiac developmental malformations, such as the appearance of pericardial edema phenotype. In addition, after 72 h of exposure, the mRNA levels of cardiac development-related genes, such as myh7, myh6, tpm1, nppa, tbx5, tbx20, myl7 and cmlc1, were significantly lower in AgNPs-treated zebrafish embryos than in control zebrafish embryos. Moreover, RNA sequencing, KEGG (Kyoto Encyclopedia of Genes) and Genomes and GSEA (gene set enrichment analysis) of the DEGs (differentially expressed genes) between the AgNPs-exposed and control groups indicated that the downregulated DEGs were mainly enriched in focal adhesion pathways. Further investigations demonstrated that the mRNA levels of focal adhesion pathway-related genes, such as igf1ra, shc3, grb2b, ptk2aa, akt1, itga4, parvaa, akt3b and vcla, were significantly decreased after AgNPs treatment in zebrafish.

Conclusion

Thus, our findings illustrated that AgNPs could impair cardiac development by regulating the focal adhesion pathway in zebrafish.

CRISPR/Cas9 Technology for Enhancing Desirable Traits of Fish Species in Aquaculture

Aquaculture, the world's fastest-growing food production sector, is critical for addressing food security concerns because of its potential to deliver high-quality, nutrient-rich supplies by 2050. This review assesses the effectiveness of CRISPR/Cas9 genome editing technology in enhancing desirable traits in fish species, including growth rates, muscle quality, disease resistance, pigmentation, and more. It also focuses on the potential effectiveness of the technology in allowing precise and targeted modifications of fish DNA to improve desirable characteristics. Many studies have reported successful applications of CRISPR/Cas9, such as knocking out reproductive genes to control reproduction and sex determination, enhancing feed conversion efficiency, and reducing off-target effects. Additionally, this technology has contributed to environmental sustainability by reducing nitrogen-rich waste and improving the nutritional composition of fish. However, the acceptance of CRISPR/Cas9 modified fish by the public and consumers is hindered by concerns regarding public perception, potential ecological impacts, and regulatory frameworks. To gain public approval and consumer confidence, clear communication about the editing process, as well as data on the safety and environmental considerations of genetically modified fish, are essential. This review paper discusses these challenges, provides possible solutions, and recommends future research on the integration of CRISPR/Cas9 into sustainable aquaculture practices, focusing on the responsible management of genetically modified fish to enable the creation of growth and disease-resistant strains. In conclusion, this review highlights the transformative potential of CRISPR/Cas9 technology in improving fish traits, while also considering the challenges and ethical considerations associated with sustainable and responsible practices in aquaculture.

In Search of a Target Gene for a Desirable Phenotype in Aquaculture: Genome Editing of Cyprinidae and Salmonidae Species

Aquaculture supplies the world food market with a significant amount of valuable protein. Highly productive aquaculture fishes can be derived by utilizing genome-editing methods, and the main problem is to choose a target gene to obtain the desirable phenotype. This paper presents a review of the studies of genome editing for genes controlling body development, growth, pigmentation and sex determination in five key aquaculture Salmonidae and Cyprinidae species, such as rainbow trout (Onchorhynchus mykiss), Atlantic salmon (Salmo salar), common carp (Cyprinus carpio), goldfish (Carassius auratus), Gibel carp (Carassius gibelio) and the model fish zebrafish (Danio rerio). Among the genes studied, the most applicable for aquaculture are mstnba, pomc, and acvr2, the knockout of which leads to enhanced muscle growth; runx2b, mutants of which do not form bones in myoseptae; lepr, whose lack of function makes fish fast-growing; fads2, Δ6abc/5Mt, and Δ6bcMt, affecting the composition of fatty acids in fish meat; dnd mettl3, and wnt4a, mutants of which are sterile; and disease-susceptibility genes prmt7, gab3, gcJAM-A, and cxcr3.2. Schemes for obtaining common carp populations consisting of only large females are promising for use in aquaculture. The immobilized and uncolored zebrafish line is of interest for laboratory use.

Genome-wide characterization of integrin (ITG) gene family and their expression profiling in half-smooth tongue sole (Cynoglossus semilaevis) upon Vibrio anguillarum infection

Integrins (ITGs) are transmembrane heterodimer receptors with ITGα subunit and ITGβ subunit, participating in various physiological processes, including immunity. At present, systematic research on ITGs in teleost is scarce, especially in half-smooth tongue sole (Cynoglossus semilaevis). In this study, a set of 28 ITG genes in half-smooth tongue sole have been identified and characterized. The phylogenetic analysis showed that ITGα and ITGβ subunits were respectively classified into five and two clusters, consistent with previous studies. The selection pressure analysis indicated that most of ITG genes were under purifying selection, except for ITGα11b and ITGαL with positive selection. The expression profiles of eight selected ITG genes, including ITGα1, ITGα5, ITGα8, ITGα11, ITGβ1, ITGβ2, ITGβ3, and ITGβ8, were analyzed in healthy tissues and after infection with Vibrio anguillarum, revealed their implications in immune response. The study provided a comprehensive characterization and expression analysis of ITG genes in half-smooth tongue sole, setting a solid foundation for further functional studies and promising potential in disease control.

Establishment of an Integrated CRISPR/Cas9 Plasmid System for Simple and Efficient Genome Editing in Medaka In Vitro and In Vivo

Although CRISPR/Cas9 has been used in gene manipulation of several fish species in vivo, its application in fish cultured cells is still challenged and limited. In this study, we established an integrated CRISPR/Cas9 plasmid system and evaluated its efficiency of gene knock-out or knock-in at a specific site in medaka (Oryzias latipes) in vitro and in vivo. By using the enhanced green fluorescent protein reporter plasmid pGNtsf1, we demonstrate that pCas9-U6sgRNA driven by endogenous U6 promoter (pCas9-mU6sgRNA) mediated very high gene editing efficiency in medaka cultured cells, but not by exogenous U6 promoters. After optimizing the conditions, the gene editing efficiencies of eight sites targeting for four endogenous genes were calculated, and the highest was up to 94% with no detectable off-target. By one-cell embryo microinjection, pCas9-mU6sgRNA also mediated efficient gene knock-out in vivo. Furthermore, pCas9-mU6sgRNA efficiently mediated gene knock-in at a specific site in medaka cultured cells as well as embryos. Collectively, our study demonstrates that the genetic relationship of U6 promoter is critical to gene editing efficiency in medaka cultured cells, and a simple and efficient system for medaka genome editing in vitro and in vivo has been established. This study provides an insight into other fish genome editing and promotes gene functional analysis.

Review of Medicinal Plants and Active Pharmaceutical Ingredients against Aquatic Pathogenic Viruses

Aquaculture offers a promising source of economic and healthy protein for human consumption, which can improve wellbeing. Viral diseases are the most serious type of diseases affecting aquatic animals and a major obstacle to the development of the aquaculture industry. In the background of antibiotic-free farming, the development and application of antibiotic alternatives has become one of the most important issues in aquaculture. In recent years, many medicinal plants and their active pharmaceutical ingredients have been found to be effective in the treatment and prevention of viral diseases in aquatic animals. Compared with chemical drugs and antibiotics, medicinal plants have fewer side-effects, produce little drug resistance, and exhibit low toxicity to the water environment. Most medicinal plants can effectively improve the growth performance of aquatic animals; thus, they are becoming increasingly valued and widely used in aquaculture. The present review summarizes the promising antiviral activities of medicinal plants and their active pharmaceutical ingredients against aquatic viruses. Furthermore, it also explains their possible mechanisms of action and possible implications in the prevention or treatment of viral diseases in aquaculture. This article could lay the foundation for the future development of harmless drugs for the prevention and control of viral disease outbreaks in aquaculture.

Sustainable use of CRISPR/Cas in fish aquaculture: the biosafety perspective

Aquaculture is becoming the primary source of seafood for human diets, and farmed fish aquaculture is one of its fastest growing sectors. The industry currently faces several challenges including infectious and parasitic diseases, reduced viability, fertility reduction, slow growth, escapee fish and environmental pollution. The commercialization of the growth-enhanced AquAdvantage salmon and the CRISPR/Cas9-developed tilapia (Oreochromis niloticus) proffers genetic engineering and genome editing tools, e.g. CRISPR/Cas, as potential solutions to these challenges. Future traits being developed in different fish species include disease resistance, sterility, and enhanced growth. Despite these notable advances, off-target effect and non-clarification of trait-related genes among other technical challenges hinder full realization of CRISPR/Cas potentials in fish breeding. In addition, current regulatory and risk assessment frameworks are not fit-for purpose regarding the challenges of CRISPR/Cas notwithstanding that public and regulatory acceptance are key to commercialization of products of the new technology. In this study, we discuss how CRISPR/Cas can be used to overcome some of these limitations focusing on diseases and environmental release in farmed fish aquaculture. We further present technical limitations, regulatory and risk assessment challenges of the use of CRISPR/Cas, and proffer research strategies that will provide much-needed data for regulatory decisions, risk assessments, increased public awareness and sustainable applications of CRISPR/Cas in fish aquaculture with emphasis on Atlantic salmon (Salmo salar) breeding.

Molecular mechanisms of intermuscular bone development in fish: a review

Intermuscular bones (IBs) are slender linear bones embedded in muscle, which ossify from tendons through a process of intramembranous ossification, and only exist in basal teleosts. IBs are essential for fish swimming, but they present a choking risk during human consumption, especially in children, which can lead to commercial risks that have a negative impact on the aquaculture of these fish. In this review, we discuss the morphogenesis and functions of IBs, including their underlying molecular mechanisms, as well as the advantages and disadvantages of different methods for IB studies and techniques for breeding and generating IB-free fish lines. This review reveals that the many key genes involved in tendon development, osteoblast differentiation, and bone formation, e.g., scxa, msxC, sost, twist, bmps, and osterix, also play roles in IB development. Thus, this paper provides useful information for the breeding of new fish strains without IBs via genome editing and artificial selection.

Molecular cloning, functional characterization and expression analysis of P65 subunit in response to GCRV infection in rare minnow (Gobiocypris rarus)

P65, the all-important subunit of the transcription factor NF-κB, plays an important role in the regulation of immune response. In this study, the cDNA of P65 subunit of rare minnow Gobiocypris rarus (GrP65) was cloned, and its expression patterns and functional role in rare minnow were investigated. The GrP65cDNA encodes a polypeptide of 573 amino acids, containing a well-conserved Rel-homology domain (RHD). The amino acid sequence analysis showed that GrP65 shared 81% and 69% identity to the grass carp (Ctenopharyngodon idella) and human (Homo sapiens) orthologous, respectively. Phylogenetic analysis revealed that GrP65 clustered with homologues from other teleosts. Cellular distribution anallysis demonstrated that GrP65 was located in the cytoplasm and nucleus. Quantitative real-time PCR analysis showed that GrP65 was ubiquitously expressed in all examined tissues, but especially highly in liver. Temporal expression analysis in vivo showed that the expression levels of GrP65 were significantly up-regulated in liver in response to GCRV infection, which suggested that GrP65 might play a crucial role in recognition and responses to GCRV infection in fish. In addition, GrP65 activated several interferon (IFN) promoters and induced the expression of downstream IFN-stimulated genes (ISGs). Furthermore, overexpression of P65 remarkably decreased the GCRV proliferation, while knockdown of P65 obtained opposite effects. In summary, we systematically characterized GrP65 and demonstrated its role in the innate immune response to GCRV infections.

Establishment of a cell line from egg of rare minnow Gobiocypris rarus for propagation of grass carp reovirus genotype II

The rare minnow, Gobiocypris rarus, is small experimental fish proven to be sensitive to Grass Carp Reovirus (GCRV) infection. In present study we established a new cell (GrE) from eggs of G. rarus. GrE cells grew well at 28 °C in M199 medium containing 10% fetal bovine serum, and has been subcultured for over 70 passages. Chromosome analysis indicated that 40% of the cells were diploid 2n = 66 while the chromosome number of the fish is 2n = 50. Viral replication in GrE cells was confirmed by transmission electron microscopy, immunofluorescence assays and virus titration experiments. GrE cells and Cyenopharyngodon idellus kidney cells were infected with two GCRV genotypes while the virus copies of GCRV II in GrE peaked at 2.25 × 10⁵ on 12th dpi. In vivo challenge experiments using GCRV I and II isolates at generations 1 and 20 indicated that GCRV II reproduce similar symptoms and histopathological changes of the disease in the rare minnow. These results indicated that GrE is permissive for GCRV genotype II propagation and can be used for pathogenesis studies and vaccine development of the predominant genotype of GCRV.