Search Results (7)

Groupers are important aquaculture species, and hybridization is an effective breeding method for genetic improvement and to enhance production efficiency in groupers. The ShanHu grouper (Epinephelus fuscoguttatus ♀ × Epinephelus polyphekadion ♂) is a hybrid grouper with potential for aquaculture development and research value. Using Illumina and PacBio sequencing platforms, as well as PacBio SMRT technology and Hi-C auxiliary mounting technology, the whole genome sequencing and assembly of the ShanHu grouper were completed, resulting in a chromosome-level genome information for this hybrid grouper. The genome assembly has a total length of 1.17 Gb with a scaffold N50 of 46.12 Mb, and 171 contigs were anchored into 24 chromosomes. Additionally, its repeat sequences and non-coding RNAs were annotated and 26,102 genes were predicted. Through comparative genomic analysis of the hybrid species ShanHu grouper and its parents, we found that comparative genomic analyses revealed centric inversion structural variations on the chromosomes of the hybrid ShanHu grouper in relation to the brown-marbled grouper and the camouflage grouper. Furthermore, the gene families of the hybrid species have expanded in pathways related to immunity and growth development. This study is the first to provide complete genomic information for a hybrid grouper, offering its full genetic information, exploring the genetic variations in the genomes of hybrid offspring, and providing data references for foundational theoretical research and grouper production practices. Full article

Vibriosis caused by Vibrio vulnificus is a major problem in aquatic animals, particularly brown marble groupers (Epinephelus fuscoguttatus). V. vulnificus biotype I has recently been isolated and classified into subgroups SUKU_G1, SUKU_G2, and SUKU_G3 according to the different types of virulence genes. In a previous study, we have shown that biotype I V. vulnificus strains were classified into three subgroups according to the different types of virulence genes, which exhibited different phenotypes in terms of growth rate and virulence. To gain insight into the different genetic features revealed by the potential virulence mechanisms of V. vulnificus in relation to a spectrum of pathogenesis, comparative genomic analyses of three biotype I V. vulnificus strains belonging to different subgroups (SUKU_G1, SUKU_G2, and SUKU_G3) were performed. The V. vulnificus genome is composed of two circular chromosomes with average sizes of 3 Mbp and 1.7 Mbp that are evolutionarily related based on the analysis of orthologous genes. A comparative genome analysis of V. vulnificus revealed 5200 coding sequences, of which 3887 represented the core genome and the remaining 1313 constituted the dispensable genome. The most virulent isolate (SUKU_G1) carries unique enzymes that are important for lipopolysaccharide (LPS) and capsular polysaccharide (CPS) synthesis, as well as flagellar glycosylation, and harbors another type of repeat in toxin (RTX) and bacterial defense mechanisms. The less virulent isolate (SUKU_G2) shares enzymes related to CPS biosynthesis or flagellar glycosylation, while the avirulent isolate (SUKU_G3) and a less virulent isolate (SUKU_G2) share enzymes related to the production of rare sugars. Interestingly, the isolates from the three subgroups containing specific CMP-N-acetylneuraminate-producing enzymes that are correlated with their growth abilities. Collectively, these observations provide an understanding of the molecular mechanisms underlying disease pathogenesis and support the development of strategies for bacterial disease prevention and control. Full article

Sperm cryopreservation is a valuable tool for breeding, conservation, and genetic improvement in aquatic resources, while oxidative damage will cause a decline in sperm quality during this progress. Melatonin (MT), a natural antioxidant hormone, is used as an additive in sperm cryopreservation to reduce cellular damage from oxidative stress. Here, we aimed to investigate the effect of adding MT to the freezing medium in sperm cryopreservation of brown-marbled grouper (Epinephelus fuscoguttatus). Different concentrations of MT (0, 0.1, 0.25, and 0.5 mg/mL) were tested. We evaluated sperm motility, viability, apoptosis, mitochondrial membrane potential (MMP), and fertilization ability to assess the effects of MT supplementation. Our results demonstrated that the addition of MT to the extender improved the post-thaw motility, MMP, and fertilization ability of brown-marbled grouper sperm. The total motility, curvilinear velocity, straight linear velocity, and average path velocity in MT-treated groups (0.1 and 0.25 mg/mL) exhibited significantly higher values than that of the control group. A higher MMP (p < 0.05) was observed in the group treated with 0.25 mg/mL MT, suggesting that supplementation of MT in the extender might be able to protect mitochondrial membrane integrity effectively. Regarding fertilizing ability, 0.25 mg/mL MT yielded a significantly higher hatching rate than the control. An adverse effect was found with the concentration of MT up to 0.5 mg/mL, suggesting the possible toxicity of a high-dose addition. In this study, we optimized the sperm cryopreservation protocol of brown-marbled grouper, which might be valuable for sperm cryopreservation and sample commercialization of groupers and other fish. Full article

The hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus) is a new species of grouper crossed from giant grouper (E. lanceolatus) as the male parent and brown-marbled grouper (E. fuscoguttatus) as the female parent. We hypothesized that optimal levels of dietary protein may benefit liver function. High-lipid diets are energetic feeds that conserve protein and reduce costs, and are a hot topic in aquaculture today. Therefore, the objective of the research is to investigated the effects of dietary protein level in high-lipid diets on serum and liver biochemistry, liver histology, and liver immune and antioxidant indexes and gene mRNA expression of the juvenile hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus). Six iso-lipidic (161 g/kg) diets were formulated containing graded levels of protein (510 as control, 480,450, 420, 390 and 360 g/kg). Each treatment consisted of three replicates and 30 fish (6.70 ± 0.02 g) in one replicate. After an 8-week feeding experiment, the results indicated the following: (1) With the decreasing of dietary protein level, the specific growth rate (SGR) of groupers increased gradually and then decreased; SGRs of the 390 and 360 g/kg groups were significantly lower than other groups (p < 0.05). (2) In terms of serum and liver, the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD), and the total antioxidant capacity (T-AOC) content, and the activity of immune enzymes such as lysozyme (LYS) and immunoglobulin (IgM) was significantly increased under the appropriate protein level. (3) Based on liver histology, we know that high or low dietary protein levels cause liver damage. (4) Dietary protein levels can significantly affect the mRNA expression levels of an anti-inflammatory factor gene (tgfβ), pro-inflammatory factor genes (il6, il8), heat shock proteins, and antioxidant and immune genes (hsp70 and hsp90, gpx, nrf2, keap1). It is concluded that the appropriate protein level can promote the growth performance of groupers, improve antioxidant activity and immune enzyme activity in serum and liver, and enhance the expression of immune genes. Full article

The Hulong hybrid grouper was bred from the brown-marbled grouper (Epinephelus fuscoguttatus) ♀ and the giant grouper (E. lanceolatus) ♂, combining the advantageous traits of both parents. Possessing an excellent performance, this hybrid’s cultivation promotes the development of the grouper industry. Its male parent, the giant grouper, possesses the fastest growth and the largest body size among all coral-reef-dwelling fish. This species is not only an economically important species in marine aquaculture, but it is also an ideal male parent in the interspecific crossing of grouper species. In the present study, a high-quality chromosome-level genome of the giant grouper was constructed with a total length of 1.06 Gb, consisting of 24 chromosomes and 69 scaffolds. To analyze the genetic differences between the parents of the Hulong hybrid grouper, the structural variations (SVs) between both parental genomes were detected, and a total of 46,643 SVs were obtained. High-quality SNPs were identified from resequencing data. There were significant differences between the two genomes, and the average F_ST reached 0.685. A total of 234 highly differentiated regions were detected with an F_ST > 0.9. The protein-coding genes involved in SVs and highly differentiated regions were significantly enriched in metabolic pathways, including fatty metabolism, carbohydrate metabolism, amino acid metabolism and the TCA cycle. These genes may be related to the differences in feeding preferences and the ability to digest carbohydrates between the two grouper species under natural conditions. In addition, protein-coding genes related to the cell cycle and p53-signaling pathway were also detected. These genes may play important roles in the regulation of body size and growth performance. This research provides genomic resources for further breeding works and evolutionary analyses. Full article

Brown-marbled grouper is one of the most important mariculture species in China and is widely used as a crossbreeding parent in the grouper industry. Enhancing growth rates is a key target in fish breeding, and gaining insight into the underlying mechanisms responsible for growth differences between individuals can aid in the improvement of grouper growth rates. However, the mechanism behind growth differences in this fish remains unclear. We analyzed the transcriptome profiles of muscle tissues between fast- and slow-growing brown-marbled grouper using RNA-seq and identified 77 significantly up-regulated genes and 92 significantly down-regulated genes in the extreme growth groups. Our findings suggest that up-regulated genes such as ghr and tnni2, as well as down-regulated genes such as stc2 and pdp1, are associated with growth advantages in brown-marbled grouper. We used differentially expressed genes (DEGs) for GO and KEGG enrichment analyses. The results of the GO enrichments showed that the significantly up-regulated genes in the fast-growing group were involved in protein folding, the actin cytoskeleton, the myosin complex, and other processes. The results of the KEGG enrichments showed that the significantly up-regulated genes in the fast-growing group were involved in various pathways such as glycolysis/gluconeogenesis, adipocytokine signaling, MAPK signaling, carbon metabolism, and PI3K-Akt signaling. Additionally, gene set enrichment analysis (GSEA) showed that the PI3K/AKT/mTOR pathway was up-regulated in the fast-growing group, which may be responsible for the higher nutrient absorption efficiency and muscle growth in these fish. Our results contribute to a better understanding of the molecular mechanisms and regulatory pathways underlying fast growth in brown-marbled grouper. However, further studies are necessary to fully elucidate the mechanisms behind growth differences between individuals. Full article

Brown marbled grouper (Epinephelus fuscoguttatus) is an apex predator from coral reefs of the Indo-Pacific region. All five published case series of ciguatera after consumption of brown marbled grouper were reviewed to characterize the types, severity and chronicity of ciguatera symptoms associated with its consumption. Three of these case series were from large outbreaks affecting over 100–200 subjects who had eaten this reef fish served at banquets. Affected subjects generally developed a combination of gastrointestinal, neurological and, less commonly, cardiovascular symptoms. Gastrointestinal symptoms occurred early and generally subsided in 1–2 days. Some neurological symptoms (e.g., paresthesia of four limbs) could last for weeks or months. Sinus bradycardia and hypotension occurred early, but could be severe and prolonged, necessitating the timely use of intravenous fluids, atropine and dopamine. Other cardiovascular and neurological features included atrial ectopics, ventricular ectopics, dyspnea, chest tightness, PR interval >0.2 s, ST segment changes, polymyositis and coma. Concomitant alcohol consumption was associated with a much higher risk of developing bradycardia, hypotension and altered skin sensation. The public should realize that consumption of the high-risk fish (especially the ciguatoxin-rich parts and together with alcohol use) and repeated ciguatoxin exposures will result in more severe and chronic illness. Full article