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BACKGROUND RESULTS CONCLUSION The aquatic processing industry is increasingly aware of the need to ensure that slaughtering is carried out under high welfare standards, so there is a need to explore the impact of slaughter methods on fish fillets. This study aimed to investigate the effects of different slaughtering methods (M1, lethality by hammering; M2, gas mixture causing death; M3, lethality by clove oil anesthesia + ice slurry; M4, lethality by ice slurry; M5, lethality by gradient cooling) on the energy metabolism, apoptosis and flesh mass in grouper (Epinephelus fuscoguttatus).Therefore, 120 fish (24 per treatment) were slaughtered by the five methods. The results showed that the succinate dehydrogenase (SDH) enzyme activity of M5 sample was higher. The serum glucose level of M2 samples and DAPI staining fluorescence of M2 samples were the highest, indicating that the stress response of M2 was strong. In addition, the texture, pH, total volatile basic nitrogen (TVB‐N), thiobarbituric acid (TBA) and K value results showed M5 samples had better flesh quality.Gradient cooling lethality had the least effect on oxidative damage and apoptosis in grouper during cold storage as the gradient cooling lethality had the least effect on antioxidant enzyme activities. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten days post hatching) through laboratory experiments offering rotifers (Brachionus sp.) and copepod nauplii as food. High-speed cameras and imaging techniques including bright field microscopy, matched filters, and holography captured rapid displacements (up to 25 body lengths per second), peduncle caudal beats (up to 40 beats s−1), turns, and resting periods. Reynolds numbers ranged from <45 for routine swimming to 222 for burst swimming. Specific behaviors, including changes in swimming velocity and body movements, were observed from three days post hatching, when feeding begins, suggestive of an array of responses to environmental forcing, predator avoidance, food search, and feeding success. These findings provide insights into the critical movement performances of E. marginatus larvae, which help to unravel their ecological interactions and survival strategies. Understanding grouper larval swimming behavior is pivotal for devising effective cultivation strategies aimed at replenishing wild stocks and enhancing production for human consumption. [ABSTRACT FROM AUTHOR]

Groupers are economically important species in the fishery and aquaculture industries in Asian countries. Various species of grouper, including hybrids, have been brought to market even without precise species identification. In this study, we analyzed the structure and expression profile of the gene encoding prolactin (PRL) in the red-spotted grouper Epinephelus akaara based on genomic DNA and cDNA templates. The results showed that the PRL gene consists of five exons encoding an open reading frame of 212 amino acids, including a putative signal peptide of 24 amino acids and a mature structural protein of 188 amino acids. It showed amino acid identities of 99% with Epinephelus coioides, 83% with Amphiprion melanopus, 82% with Acanthopagrus schlegelii, 75% with Oreochromis niloticus, 70% with Coregonus autumnalis, and 67% with Oncorhynchus mykiss, indicating its closer similarity to E. coioides and other groupers but marked distinction from non-teleost PRLs. PRL mRNA expression was detected mostly in the brain, including the pituitary gland, with little expression in other tissues. While the 5-exon structure of the PRL gene of red-spotted grouper and the exon sizes were conserved, the sizes of the introns, particularly the first intron, were markedly different among the grouper species. To examine whether these differences can be used to distinguish groupers of similar phenotypes, exon-primed intron-crossing analysis was carried out for various commercially important grouper species. The results showed clear differences in size of the amplified fragment encompassing the first intron of the PRL gene, indicating that this method could be used to develop species-specific markers capable of discriminating between grouper species and their hybrids at the molecular level.

The effects of microalgae Chlorella pyrenoidosa on the hybrid groupers' (Epinephelus lanceolatus♂ × E. fuscoguttatus♀) growth, gut microbiome, and transcriptome were examined in this study. Feeding trials with a duration of 15 days (15d) and 60 days (60d) were conducted on three experimental groups (n = 3) as follows: (T1) grouper fed with basal diet and reared in filtered seawater (control treatment); (T2) grouper fed with basal diet and reared in C. pyrenoidosa monoculture water (CMW); and (T3) grouper fed with basal diet partially replaced with 15% of dried C. pyrenoidosa (CRM) and reared in filtered seawater. The findings revealed that groupers reared 15d in T2 treatment (T2-15d) had a higher fat content, with an apparent shift of microbial composition and functional pathways in the gut. Groupers reared 60d in T2 treatment (T2-60d) displayed an increased NADH dehydrogenase and cytochrome c oxidases gene expression, indicating more robust oxidative phosphorylation activity and ATP production crucial for metabolic homeostasis. The reduction in the total amino acid content was also detected in groupers raised in T2-60d. Gastritis, enteritis, and lipid malabsorption syndrome were observed in groupers raised 60d in T3 treatment (T3-60d), with the condition likely due to a higher intake of omega-6 to omega-3 fatty acids ratio in groupers raised 15 days in T3 (T3-15d) and T3-60d. All signs of intestinal inflammation may arise from the inclusion of dried C. pyrenoidosa. Overall, outcomes from this study revealed that introducing live C. pyrenoidosa to the culture water is advantageous for digestion and enhances the energy metabolism of juvenile groupers. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of hypoxia and ammonia-N co-exposure on oxygen consumption, glucose metabolism and amino acid metabolism in hybrid grouper. The results showed that elevated expression of GLUT1, MCT1, PFK, HK and LDH were induced by co-exposure to hypoxia and ammonia. In addition, co-exposure to hypoxia and ammonia reduced the tolerance of hybrid grouper to ammonia-N. Furthermore, ammonia-N exposure caused an increase in oxygen consumption in hybrid grouper. After ammonia-N exposure for 96 h, 10 amino acids contents and activities of AST and ALT elevated in hybrid grouper muscle. The study revealed that combined exposure to hypoxia and ammonia-N significantly increased glucose metabolism, oxygen consumption and amino acid metabolism in hybrid grouper, and presented significant synergistic effects. [ABSTRACT FROM AUTHOR]

Simple Summary: Probiotics, beneficial bacteria that contribute to the health of both humans and animals, play a crucial role in aquaculture by enhancing digestion and bolstering disease resistance in fish. However, the efficacy of probiotics can vary significantly, even among strains of the same species, based on their origin. This study focused on evaluating the effects of three different Bacillus subtilis strains, derived either from the host fish or external sources, on fish growth and disease resilience. Our findings indicate that the host-derived strain, 6-3-1, offered superior benefits in terms of growth enhancement and health improvement compared to the externally-derived strains. This research underscores the importance of the probiotic source, demonstrating that origin can significantly influence effectiveness. The outcomes suggest the potential for customized probiotic applications to advance aquaculture practices substantially. In the realm of modern aquaculture, the utilization of probiotics has gained prominence, primarily due to their ability to enhance growth, boost immunity, and prevent diseases in aquatic species. This study primarily investigates the efficacy of Bacillus subtilis strains, both host-derived and from other sources, in influencing fish growth, immunity, lipid metabolism, and disease resistance. Employing a 42-day feeding trial, we divided hybrid grouper into four distinct groups: a control group on a basal diet and three experimental groups supplemented with 1 × 108 CFU/g of different Bacillus subtilis strains-BS, 6-3-1, and HAINUP40. Remarkably, the study demonstrated that the 6-3-1 and HAINUP40 groups exhibited significant enhancements across key growth parameters: final body weight (FBW), weight gain rate (WGR), feed intake (FI), feed efficiency ratio (FER), and feed conversion ratio (FCR). The investigation into lipid metabolism revealed that the 6-3-1 strain upregulated seven metabolism-related genes, HAINUP40 affected four metabolism-related genes, and the BS strain influenced two metabolism-related genes, indicating diverse metabolic impacts by different strains. Further, a notable reduction in liver enzymes AST and ALT was observed across all supplemented groups, implying improved liver health. Noteworthy was the BS strain's superior antioxidative capabilities, positively affecting all four measured parameters (CAT, GSH-Px, MDA). In the sphere of immune-related gene expression, the BS strain significantly decreased the expression of both inflammation and apoptosis-related genes, whereas the HAINUP40 strain demonstrated an upregulation in these genes. The challenge test results were particularly telling, showcasing improved survival rates against Vibrio harveyi infection in the BS and 6-3-1 groups, unlike the HAINUP40 group. These outcomes highlight the strain-specific nature of probiotics and their varying mechanisms of action within the host. In conclusion, this study reveals that probiotic strains, varying by source, demonstrate unique, strain-specific effects in promoting growth and modulating immunity in hybrid grouper. This research highlights the promise of tailored probiotic applications in improving aquaculture practices. Such advancements contribute to more sustainable and efficient fish farming methods. [ABSTRACT FROM AUTHOR]

Abstract Background Hybridization is a useful strategy to produce offspring with more desirable phenotypic characteristics than those of parents. The hybrid grouper derived from the cross of Cromileptes altivelis (♀, 2n = 48) with Epinephelus lanceolatus (♂, 2n = 48) exhibits improved growth compared with its female parent, which makes it valuable to aquaculture. However, the genetic traits of the hybrid grouper are poorly understood. Results The observations showed that the hybrid grouper was diploid (2n = 48) and displayed intermediate morphology with the parent's measurable characteristics. The ribosomal DNA (rDNA) and mitochondria DNA (mtDNA) were characterized at molecular and phylogenetic level. High similarity and low genetic distance of 5S rDNA and mtDNA sequences between the hybrid grouper and C. altivelis showed that the hybrid grouper had a closer genetic relationship with female parents. The reconstructed phylogenetic tree based on COI gene and D-loop region of mtDNA recovered that mtDNA was maternally inherited in the hybrid grouper. Additionally, the DNA methylation level of 5S rDNA intergenic spacers (IGS) sequence was tested in here. The results showed that the DNA methylation status of the hybrid grouper was significantly lower than that of C. altivelis. Conclusion Results of this study provide important data on the genetic characteristics of the hybrid derived from the cross of C. altivelis and E. lanceolatus, and contribute the knowledge of both evolution and marine fish breeding.

Globally, groupers (Serranidae) are commercially important fish species. Hybridization within this family has been reported in captivity and natural environments, usually among congeneric species. However, intergeneric hybridization has been reported only occasionally. Given the commercial interest in these fish, artisanal or recreational fishermen easily notice "weird-looking" individuals. This is the case of an unidentified grouper noticed by a spearfisher in Lebanese Mediterranean waters. Visual comparisons raised the possibility that the observed specimen was a hybrid. Molecular analysis based on two mitochondrial and three nuclear markers was performed to investigate this potential hybrid's affinity. The discordance of the phylogenetic gene trees of the mitochondrial and nuclear markers indicates that E. marginatus and M. rubra are potential parent species of a hybrid individual in our samples. The subsequent haploweb analysis based on the S7 nuclear marker reveals the affinity of the hybrid individual to both E. marginatus and M. rubra. In this specific hybridization case, the nuclear marker S7 emerges as a valuable diagnostic tool for species delineation and hybrid detection. [ABSTRACT FROM AUTHOR]

Groupers are among the fish groups that are difficult to recognize due to their high morphological similarities. Therefore, molecular techniques, particularly DNA barcoding, are extensively utilized to differentiate this fish group. This study aimed to analyze and validate six grouper species belonging to the Epinephelidae family that were harvested from Langsa district waters in Aceh province, Indonesia, based on DNA barcode data. It was conducted from June to December 2021, with the fish specimens collected from fishers at fish landing sites and the fish market in Langsa City, Aceh province. A total of 22 grouper sequences belonging to six species were generated, namely Epinephelus coioides, E. bleekeri, E. malabaricus, E. erythrurus, E. sexfasciatus and Mycteroperca poecilonotus (formerly Epinephelus poecilonotus). Genetic distance within these species ranged from 0.10 to 0.73% (average: 0.40%). Notably, E. malabaricus and E. coioides exhibited the closest genetic kinship (4.07%), while E. sexfasciatus and M. poecilonotus displayed the greatest genetic distance (19.33%). This study provides the first DNA reference for grouper in Langsa district, Indonesia, with significant implications for future sustainable grouper management. [ABSTRACT FROM AUTHOR]

Animal body size variation is of particular interest in evolutionary biology, but the genetic basis remains largely unknown. Previous studies have shown the presence of two parallel evolutionary genetic clusters within the fish genus Epinephelus with evident divergence in body size, providing an excellent opportunity to investigate the genetic basis of body size variation in vertebrates. Herein, we performed phylotranscriptomic analysis and reconstructed the phylogeny of 13 epinephelids originating from the South China Sea. Two genetic clades with an estimated divergence time of approximately 15.4 million years ago were correlated with large and small body size, respectively. A total of 180 rapidly evolving genes and two positively selected genes were identified between the two groups. Functional enrichment analyses of these candidate genes revealed distinct enrichment categories between the two groups. These pathways and genes may play important roles in body size variation in groupers through complex regulatory networks. Based on our results, we speculate that the ancestors of the two divergent groups of groupers may have adapted to different environments through habitat selection, leading to genetic variations in metabolic patterns, organ development, and lifespan, resulting in body size divergence between the two locally adapted populations. These findings provide important insights into the genetic mechanisms underlying body size variation in groupers and species differentiation. [ABSTRACT FROM AUTHOR]

To investigate the effect of hydroalcoholic extract of rosemary (Rosmarinus officinalis) on chemical, microbial and sensory indices of grouper (Epinephelus coioides) in refrigerated conditions, four treatment groups: control treatment (uncoated fillets), fillet coated with rosemary 0.1%, Fillet covered with rosemary 0.2% and fillet covered with 0.4% rosemary were run. The 100 gr of samples were stored at refrigerator (4°C) for 15 days. The measurements were undertaken at 0, 5, 10 and15 days at the beginning of the experiment. Generally, peroxide value (PV), thiobarbituric acid (TBA), total volatile base nitrogen (TVN), pH, counting total bacteria, counting cold-loving bacteria were significantly increased with storage time (P<0.05). The results showed that the use of rosemary extract improved the quality of chilled grouper. [ABSTRACT FROM AUTHOR]

Astaxanthin (ASX) shows strong antioxidant property and is widely used as a fish feed additive. However, the underlying molecular mechanism of how ASX improves the ability of fish to resist bacterial infection remains largely unknown. To investigate the effects of dietary ASX from Haematococcus pluvialis on pearl gentian grouper, transcriptome combined with intestinal microbe analysis was conducted. The results of RNA-Seq analysis demonstrated that compared with the control group, the differently expressed genes of ASX-treated group were enriched in AMPK, autophagy, HIF-1, and PI3K-Akt signaling pathway. 16 s rDNA of intestinal microbiota analysis revealed that the dominant bacteria in the intestine of fish fed with ASX were Proteobacteria and Bacteroidetes. Moreover, ASX-fed significantly reduced the level of reactive oxygen species (ROS) and NF-κb mRNA expression in fish with bacterial infection. ASX treatment also prolonged the survival time of fish in the infection condition. Our work reveals that ASX systematically improves the antibacterial ability of grouper by regulating AMPK, autophagy, HIF-1, and PI3K-Akt signaling pathway and assisting in the colonization of intestinal dominant flora. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Investigations into the correlation between growth characteristics and DNA methylation levels, along with genetic variations, can provide fundamental insights to enhance growth performance in groupers. The Myostatin (mstn) gene plays a vital role in regulating skeletal muscle development and growth. This study scrutinized the DNA methylation levels of the mstn gene across hybrid groupers (E. fuscoguttatus (♀) × E. polyphekadion (♂)) and their parental species, to evaluate its impact on growth attributes in grouper fish. The nucleotide sequence of the mstn gene was directly sequenced in the hybrid grouper, exhibiting different growth performance to identify the single nucleotide polymorphisms (SNPs) of the mstn gene and explore their correlation with growth characteristics. The findings revealed no significant differences in global DNA methylation levels within muscle tissue among the hybrid grouper and parents. However, significant differences in DNA methylation sites were discovered between the hybrid grouper and E. polyphekadion at sites 824 and 1521 (located at exon 2 and intron 2, respectively), and between E. fuscoguttatus and E. polyphekadion at site 1521. These variations could potentially influence the mRNA expression of the mstn gene. The study also identified that SNP g.1003 T > C in exon 2 of the mstn gene was significantly associated with various growth traits including body weight, total length, body length, head length, caudal peduncle height, and body height (p < 0.01). Specimens with the TT genotype at site 1003 demonstrated superior growth performance compared to those with the TC genotype. Furthermore, microstructural analyses of muscle tissue showed that the average area and diameter of muscle fibers in TT genotype individuals were significantly greater than those in TC genotype individuals. Therefore, this research provides robust evidence linking the DNA methylation level and polymorphisms of the mstn gene with growth traits, which could be beneficial for grouper breeding programs. [ABSTRACT FROM AUTHOR]

Background: Hybridization is a useful strategy to produce offspring with more desirable phenotypic characteristics than those of parents. The hybrid grouper derived from the cross of Cromileptes altivelis (♀, 2n = 48) with Epinephelus lanceolatus (♂, 2n = 48) exhibits improved growth compared with its female parent, which makes it valuable to aquaculture. However, the genetic traits of the hybrid grouper are poorly understood. Results: The observations showed that the hybrid grouper was diploid (2n = 48) and displayed intermediate morphology with the parent's measurable characteristics. The ribosomal DNA (rDNA) and mitochondria DNA (mtDNA) were characterized at molecular and phylogenetic level. High similarity and low genetic distance of 5S rDNA and mtDNA sequences between the hybrid grouper and C. altivelis showed that the hybrid grouper had a closer genetic relationship with female parents. The reconstructed phylogenetic tree based on COI gene and D-loop region of mtDNA recovered that mtDNA was maternally inherited in the hybrid grouper. Additionally, the DNA methylation level of 5S rDNA intergenic spacers (IGS) sequence was tested in here. The results showed that the DNA methylation status of the hybrid grouper was significantly lower than that of C. altivelis. Conclusion: Results of this study provide important data on the genetic characteristics of the hybrid derived from the cross of C. altivelis and E. lanceolatus, and contribute the knowledge of both evolution and marine fish breeding. [ABSTRACT FROM AUTHOR]

In order to investigate the simultaneous exposure to hypoxia and ammonia-N on oxidative stress, immune response, and apoptosis of the hybrid grouper, 120 healthy groupers were selected for hypoxia and/or ammonia-N exposure experiment. The fish were divided into four experimental groups: hypoxia and ammonia-N group, hypoxia group, ammonia-N group, and control group. The results demonstrated that ammonia-N and hypoxia exposures induced the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities increased first and then decreased, and malondialdehyde (MDA) accumulated. Additionally, antioxidant genes (SOD, CAT, GSH-Px, HSP70, and HSP90), apoptosis genes (p53, bax, caspase 3, caspase 8, and caspase 9), and inflammatory genes (TNF-α, IL-1β, IL-6, and IL-8) were upregulated by hypoxia and ammonia-N exposure. Severe inflammatory features were noticed in fish under hypoxia and ammonia-N co-exposure and speculating that the p53-bax pathway may induce apoptosis in hybrid groupers. Furthermore, hybrid grouper exposed to hypoxia or ammonia-N revealed some abnormalities in liver histology, with combined exposure resulting in the most severe liver tissue lesions. In summary, the hypoxia and ammonia-N co-exposure induced oxidative stress, accelerating the cell damage and activated inflammation and apoptosis. [ABSTRACT FROM AUTHOR]

Orange spotted grouper (Epinephelus coioides) is an important mariculture fish, and genomic breeding of this grouper species has been hindered due to lack of efficient genotyping tools. Here, we developed a single nucleotide polymorphism (SNP) genotyping technology based on multiplex PCR enrichment capture sequencing, which mainly aims at target area for high-throughput sequencing, and 741 SNPs were designed for genomic selection (GS) of growth and ammonia tolerance traits at the same time. The multiplex PCR enrichment capture sequencing assay showed that the genotyping efficiency was more than 99% in the orange-spotted grouper and the predictive accuracy of body weight and ammonia tolerance traits was 82% and 96%, respectively. More importantly, the average identity of the sequences with these SNPs aligned to the genomes of giant grouper (E. lanceolatus) and brown-marbled grouper (E. fuscoguttatus) were both over 96%. Test data showed that the SNP genotyping efficiency was more than 94% in both giant grouper and brown-marbled grouper. In summary, these results indicated that the development of SNP loci and genotyping approach based on the multiple PCR enrichment capture sequencing are suitable for GS of growth and ammonia tolerance traits in various grouper species, and it would provide technical support for practical grouper breeding.

Groupers are a commercial group of reef fish found worldwide in the warmer waters, including Indonesia. Epinephelus is one of the dominant genus in the Indonesian waters of the Aceh province waters, where three species Epinephelus areolatus , Ephinephelus fasciatus , and Ephinephelus merra are frequently caught by fishermen in the northern region. However, information on the morphological and genetic variations of the species are limited. Therefore, the objective of the present study was to document morphological and genetic variations of the species in addition to validate their taxonomic and kinship status. The specimens were collected from June to December 2020 at Lampulo fishing port Banda Aceh, Aceh, Indonesia. A total of 180 Epinephelus samples representing 60 samples of each species were used for the morphometric analysis. Of these, ten individuals were randomly taken for DNA analysis based on the Cytochrome c oxidase I (COI) gene. One-way ANOVA and Discriminant Function Analysis (DFA) were performed to distinguish morphometric variations among species. Morphological analysis displayed that E. fasciatus and E. merra had high similarities, while E. areolatus was distinguished from others. The genetic analysis showed grouper samples were differentiated into three species namely of E. fasciatus, E. merra and E. areolatus. The closest genetic distance was between E. fasciatus and E. merra (12.81%), while the farthest genetic distance was between E. areolatus and E. merra (16.05%). The two methods used in this study can be used to validate the taxonomic status of a species. [ABSTRACT FROM AUTHOR]

Copyright of Marine Fisheries: Jurnal Teknologi & Manajemen Perikanan Laut is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some fish in tropical and subtropical waters exhibit moon-related rhythmicity in their reproduction and migration. We investigated the involvement of the subtypes of cryptochrome (mgCry) in moon-related rhythmicity of the Malabar grouper Epinephelus malabaricus, which spawns around the new moon period. Under natural photoperiodic conditions, the levels of mgCry1 and mgCry2 showed daily variation with peaks at 11:00 and 19:00, respectively, in the diencephalon (including the pituitary), regardless of the moon phase. The weekly changes in mgCry2, but not mgCry1, were moon-dependent, with higher levels around the new moon. When fish were reared under natural moonlight, mgCry2 in the pituitary was higher at 15:00 and 11:00 during the new moon period than the full moon period. Rearing fish under moonlight-exposed or moonlight-blocked conditions resulted in increases in mgCry genes in the pituitary during the night at full moon, suggesting that the pituitary is a target organ of the moonlight-dependent clock system. These findings indicate that mgCry genes in the brain of the Malabar grouper exhibits moon dependency, with changes according to the duration of darkness at night. We conclude that weekly changes in Cry genes in the brain play a role in entraining moon-dependent events in the Malabar grouper. [ABSTRACT FROM AUTHOR]

Cantang grouper (Epinephelus sp.) is a fish with a high economic value and has been widely cultivated. VNN disase, caused by Betanodavirus infection, can lead to mass mortality of cantang grouper. Precautions considered effective in preventing Viral nervous necrosis (VNN) disease include vaccination. This study aimed to determine the effect of administering recombinant Chlorella vulgaris protein nanovaccine based on chitosan hybrid nanoparticles in increasing the immune response of cantang grouper infected with VNN. The study consisted of five treatments: K+ (cantang grouper infected with VNN), K- (healthy cantang grouper), T1 (healthy cantang grouper given 33 µl of nanovaccine and then challenged with VNN), T2 (healthy cantang grouper given 66 µl of nanovaccine and then tested with a VNN challenge), and T3 (healthy cantang grouper given 112 µl of nanovaccine and then tested with a VNN challenge). The parameters observed were haematology, nanovaccine Relative percent survival (RPS), and Survival rate (SR) levels. The study results showed that administering the nanovaccine increased the immune response of the fish, as indicated by an increase in haematology response, RPS, and SR in cantang grouper compared to the treatment without nanovaccine administration. The best dose of nanovaccine in this study is 33 µl. [ABSTRACT FROM AUTHOR]

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten days post hatching) through laboratory experiments offering rotifers (Brachionus sp.) and copepod nauplii as food. High-speed cameras and imaging techniques including bright field microscopy, matched filters, and holography captured rapid displacements (up to 25 body lengths per second), peduncle caudal beats (up to 40 beats s−1), turns, and resting periods. Reynolds numbers ranged from E. marginatus larvae, which help to unravel their ecological interactions and survival strategies. Understanding grouper larval swimming behavior is pivotal for devising effective cultivation strategies aimed at replenishing wild stocks and enhancing production for human consumption.

To study the effects of L-Arginine (Arg) on immune responses and intestinal structure in a hybrid grouper (Epinephelus fuscoguttatus ♀× Epinephelus lanceolatus ♂), intraperitoneal injection of different Arg doses (0, 50, 100, 200 mg per kg body weight of grouper) was administered once every seven days, repeating the process three times in the present study. A total of 216 groupers (initial weight of 349.42 ± 0.67 g) were randomly divided into four groups with three replicates, and each of the replicates comprised 18 fish. Serum was sampled at the seven, 14, and 21 days post-injection. The results showed that injection of Arg had a significant effect on serum albumin, immunoglobulin M (IgM), total protein (TP) and nitric oxide (NO) content, as well as nitric oxide synthase (NOS) and lysozyme activity (P

To investigate the relationship between lipid oxidation and the development of volatile compounds (VOCs) in grouper lipid during cold storage, lipids were extracted from grouper as a single-factor study to avoid the complex interactions between microorganisms and proteins. Lipid oxidation during storage and the content of 12 long-chain fatty acids (FAs) in grouper lipids were evaluated. The HS-SPME-GC–MS technique was used to analyze the VOCs in grouper lipids, and a total of 13 key VOCs, primarily comprising alcohols and aldehydes, were screened. Pearson correlation analysis showed a strong acorrelation between these 13 key VOCs, which influenced the overall flavor of grouper lipids, and lipid oxidation, mainly involving secondary oxidation of lipids and the oxidation of long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Possible solutions for grouper lipid deterioration were proposed, providing a reference for maintaining the overall quality of grouper and regulating flavor formation.

Levels of dietary carbohydrates and lipids have important effects on the growth, health, and glycolipid metabolizing capacity of the hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). This experiment evaluated the effect of carbohydrate to lipid ratios (CHO:L ratio) on growth, serum biochemical indices, intestinal morphology and activity of digestive enzymes, and the ability to metabolize carbohydrates and lipids in the hybrid grouper. Six iso-nitrogenous (500 g/kg) and iso-energetic (190 MJ/kg) feeds with CHO:L ratios of 0.82, 1.03, 1.28, 1.58, 1.94, and 2.27 were formulated. The 720 groupers with an initial body weight of 7.76 ± 0.08 g were sorted into 24 fiberglass buckets of 30 fish each. Feed was delivered twice daily at 8:00 and 16:00 to apparent satiety for 56 days. The results showed that the growth performance of the groupers was not significantly affected by the diet. Based on the specific growth rate (SGR), the optimal CHO:L ratio was 1.72 for the groupers by the second-order polynomial regression model. The intestinal trypsin and lipase, and the hepatic trypsin activities of the groupers showed a maximum in the 1.58 group. The intestinal muscle thickness in the 1.94 group and the villus length in the 1.58 group were significantly greater than in the 0.82, 1.03, 1.28, and 2.27 groups. The glycogen synthase, pyruvate kinase, and hexokinase activities of the liver were significantly higher in the 1.58 group than in the 0.82 and 2.27 groups. The hormone-sensitive triglyceride lipase, adipose triglyceride lipase, acetyl-CoA carboxylase, and carnitine palmitoyl transferase of the liver showed significantly higher activities in the 1.58 group than those in the 0.82 and 1.03 groups. These results showed that based on the SGR of the groupers, the best CHO:L ratio was 1.72. An appropriate dietary CHO:L ratio can reduce the lipid deposition of the fish body, liver, and muscle, as well as improve the intestinal morphology and activities of liver carbohydrate and lipid metabolism enzymes. [ABSTRACT FROM AUTHOR]

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 FST reached 0.685. A total of 234 highly differentiated regions were detected with an FST > 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. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the impact of oleic acid supplements on the liver metabolome of hybrid grouper fingerlings (Epinephelus fuscoguttatus × Epinephelus lanceolatus) challenged with Vibrio vulnificus. Oleic acid was used as a fish feed supplement because it has been reported to enhance the immune response of fish. After six weeks of feeding trials with the control and experimental diets (oleic acid immunostimulant), 10 fish were randomly selected from each treatment and challenged with V. vulnificus by immersion for 30 min. After seven days of post-bacterial challenge, the liver samples of surviving infected groupers were dissected and used for metabolomics fingerprinting using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-qTOF-MS). The results were then analyzed using MetaboAnalyst 5.0 and SIMCA+P software. From the analyses conducted, out of 639 primary metabolites detected, a total of 66 metabolites were significantly identified from the liver samples of grouper fed control and oleic acid diets. Further analysis also showed that the control and oleic acid diets have significantly different metabolites by the discriminating clustering of samples based on the PLS-DA analysis. Based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, the known metabolites pathways with high impact values are alanine, aspartate, and glutamate metabolism (0.13) followed by purine metabolism pathways (0.05). Moreover, out of these highly impacted metabolic pathways, L-glutamine (8.71%), L-lysine (4.05%), L-carnitine (11.53%), and inosine (10.49%) were the several metabolites that were highly abundant in the liver sample of surviving infected hybrid groupers fed with dietary oleic acid. The changes of metabolites contributed to improving the immune system of the fish. Thus, our results advance our understanding of the immunological regulation of the hybrid groupers' immune response toward oleic acid immunostimulants against Vibrio infection. [ABSTRACT FROM AUTHOR]

Reef fish have a high economic value. Excessive fishing causes degradation of reef fish resources, as has occurred in the West Sumatera waters. Marine protected areas (MPA) offer one of the better management strategies in support of the restoration of the overexploited fish resources by protecting fish habitat and limiting exploitation. This study aims to analyze the impacts of the establishment of MPA on reef fish resources in its adjacent areas. The research was carried out in Pieh MPA and its adjacent areas located in the West Sumatra waters. Fishing experiments were conducted inside the core zone of the MPA and the catch was compared to similar experiments outside MPA. The result showed that the catch per unit effort (CPUE) of reef fishes in the core zone of MPA was 2.47 times higher than that of in the outside of MPA. However, the size composition was not significantly different between those two areas, except for Lutjanus russellii, which shows that the maximum length inside MPA was about 2.5 times higher. The length and weight of Epinephelus areolatus were analyzed to determine the biological condition of the grouper caught in both areas. The length-weight analysis shows that 86.67% of E. areolatus were matured. Nevertheless, the length of maturity in the MPA is smaller, indicating there is the impact of epreviously fishing pressure on E. areolatus. Research results showed that the MPA is double in fish abundance. [ABSTRACT FROM AUTHOR]

Understanding the patterns of genetic diversity of species and precise stock identification are important in fisheries conservation management. However, studies on genetic diversity, connectivity, population structure, and gene flow of groupers within the Indo-Malaya Archipelago (IMA) waters are limited. The objective of the present study was to examine the phylogeographic patterns of the family Epinephelidae in IMA waters based on a parallel study of five selected species utilizing the mitochondrial COI. The grouper species were: areolate grouper (Epinephelus areolatus), blacktip grouper (Epinephelus fasciatus), sixbar grouper (Epinephelus sexfasciatus), blue-lined hind (Cephalopholis formosa), and white-edged lyretail (Variola albimarginata). Specimens were obtained from fish landing sites and fish markets from 23 locations throughout the IMA waters. This study showed genetic structuring for two species (Epinephelus areolatus and Variola albimarginata) but genetic homogeneity for the other three investigated species across IMA. Various geological and demographic histories, local and regional oceanographic features, and biological characteristics are hypothesized to shape the present genetic pattern of each species across the IMA waters. The establishment of effective international cooperation is encouraged to manage grouper species stocks in this region. [ABSTRACT FROM AUTHOR]

In the realm of modern aquaculture, the utilization of probiotics has gained prominence, primarily due to their ability to enhance growth, boost immunity, and prevent diseases in aquatic species. This study primarily investigates the efficacy of Bacillus subtilis strains, both host-derived and from other sources, in influencing fish growth, immunity, lipid metabolism, and disease resistance. Employing a 42-day feeding trial, we divided hybrid grouper into four distinct groups: a control group on a basal diet and three experimental groups supplemented with 1 × 108 CFU/g of different Bacillus subtilis strains-BS, 6-3-1, and HAINUP40. Remarkably, the study demonstrated that the 6-3-1 and HAINUP40 groups exhibited significant enhancements across key growth parameters: final body weight (FBW), weight gain rate (WGR), feed intake (FI), feed efficiency ratio (FER), and feed conversion ratio (FCR). The investigation into lipid metabolism revealed that the 6-3-1 strain upregulated seven metabolism-related genes, HAINUP40 affected four metabolism-related genes, and the BS strain influenced two metabolism-related genes, indicating diverse metabolic impacts by different strains. Further, a notable reduction in liver enzymes AST and ALT was observed across all supplemented groups, implying improved liver health. Noteworthy was the BS strain’s superior antioxidative capabilities, positively affecting all four measured parameters (CAT, GSH-Px, MDA). In the sphere of immune-related gene expression, the BS strain significantly decreased the expression of both inflammation and apoptosis-related genes, whereas the HAINUP40 strain demonstrated an upregulation in these genes. The challenge test results were particularly telling, showcasing improved survival rates against Vibrio harveyi infection in the BS and 6-3-1 groups, unlike the HAINUP40 group. These outcomes highlight the strain-specific nature of probiotics and their varying mechanisms of action within the host. In conclusion, this study reveals that probiotic strains, varying by source, demonstrate unique, strain-specific effects in promoting growth and modulating immunity in hybrid grouper. This research highlights the promise of tailored probiotic applications in improving aquaculture practices. Such advancements contribute to more sustainable and efficient fish farming methods.

Separated drift tube linac (SDTL) structure, operating on the TM010 wave, does not contain focusing elements in the drift tubes. The use of SDTL at frequencies on the order of 300 MHz to accelerate hydrogen ions at low energies, on the order of several MeV, is hampered by the significant spreading of bunches in the intercavity gaps. We have proposed a technique for forming the geometry of SDTL cavities in which particles pass through one or two periods in phase—90°. The boundaries for tuning the field magnitude in grouping periods have been determined. Examples of cavities are given. [ABSTRACT FROM AUTHOR]

[Objectives] This study aimed to investigate the sequence structure and function of Myostatin (MSTN) gene in the hybrid grouper (Epinephelus fuscoguttatus, x Epinephelus polyphekadion, ). [Methods] Genetic DNA samples were extracted from the caudal fins of the hybrid grouper and its parents to amplify their MSTN genes. Then, MSTN gene sequences were analyzed using bioinformatics tools to predict their protein structures and functions. [Results] The hybrid grouper and its parents shared the same MSTN gene structure, consisting of three exons and two introns. Nucleotide sequence of the gene could be translated into 376 amino acids, including an N-terminal signal peptide, a proteolytic processing site (RXXR motif), and nine conserved cysteine residues at C-terminal, which were the typical features of transforming growth factor beta (TGF-β) superfamily proteins. Alignment of protein sequence showed that MSTN was highly conserved between the hybrid grouper and its parents. Especially, exon 3, an important functional domain, exhibited a sequence similarity of 100% among them. In addition, four variable amino acid residues were detected in exon 2 at positions 141, 153, 185 and 186 in the hybrid grouper, but they did not affect the secondary structure of the protein. [Conclusion] These results wiil provide molecular information for future investigation on the growth and heterosis of hybrid grouper species, and on the roles of MSTN gene in regulating the growth traits of the hybrid grouper. [ABSTRACT FROM AUTHOR]

Groupers (Family Epinephelidae) are important to commercial, subsistence, and recreational fisheries throughout the world. Grouper species have complex life histories that make them more vulnerable to exploitation. While there has been extensive research on some, the majority of groupers lack sufficient life history information for proper management. The yellow-edge lyretail grouper, Variola louti, has life history gaps that need to be filled and lacks regional life history information for Guam. Age, growth, and reproduction were assessed from fishery-dependent samples collected from around Guam from 2010 to 2017. Variola louti ranged from 19.4 to 49.7 cm fork length (FL) and 2 to 17 years old. Due to the size selectivity of the fishery, a Bayesian von Bertalanffy growth model was applied. The von Bertalanffy growth parameters were L∞ = 43.7 cm FL, k = 0.28, and t0 = − 0.2. Protogynous hermaphroditism was confirmed with females reaching reproductive maturity at 26.0 cm FL (L50) and 2.6 years (A50) and female to male sex change at 35.3 cm FL (LΔ50) and 6.1 years (AΔ50). Sex ratio was 1.5 females per male, excluding transitional individuals. Using Hoenig's method, natural mortality was estimated at 0.37 year−1. The life history of Variola louti suggests that it is a relatively fast growing and early maturing grouper that is not as vulnerable to exploitation as larger bodied, slower growing groupers. However, future monitoring of sex ratio, size at maturity, and size at sex change is recommended to track and manage fishery effects, such as the recent scuba spear ban in Guam, on the life history and population status of this species. [ABSTRACT FROM AUTHOR]

Vibrio alginolyticus is the common pathogen affecting various species of marine organisms. It has been demonstrated that fliR is a necessary virulence factor to adhere and infect their hosts for pathogenic bacteria. Frequent disease outbreaks in aquaculture have highlighted the necessity of developing effective vaccines. In the present study, in order to investigate the function of fliR in V.alginolyticus, the fliR deletion mutant ΔfliR was constructed and its biological properties were evaluated, additionally, the differences in gene expression levels between wildtype and ΔfliR were analyzed by transcriptomics. Finally, ΔfliR was used as a live attenuated vaccine to immunize grouper via the intraperitoneal route to evaluate its protective effect. Results show that fliR gene of V. alginolyticus was identified as being 783 bp in length, encoding 260 amino acids, and showing significant similarity to homologs of other Vibrio species. The fliR-deletion mutant ΔfliR of V. alginolyticus was successfully constructed, and its biological phenotype analysis showed no significant differences in growth capacity and extracellular enzyme activity compared to the wild-type. However, a substantial reduction of motility ability was detected in ΔfliR. Transcriptomic analysis revealed that the absence of fliR gene is responsible for a significantly decreased expression of flagellar genes, including flaA, flaB, fliS, flhB and fliM. The fliR-deletion mainly affects the related pathways involved in cell motility, membrane transport, signal transduction, carbohydrate metabolism, and amino acid metabolism in V. alginolyticus. The efficacy of ΔfliR as a candidate of live attenuated vaccine were evaluated by intraperitoneal injection in grouper. The ΔfliR provided the RPS (Relative protection rate) of 67.2% against V. alginolyticus in groupers. The DfliR efficiently stimulated antibody production with specific IgM still detected at 42 d post-vaccination, and significantly elevated the activity of antioxidant enzymes like Catalase (CAT), Superoxide dismutase (SOD), and lactate dehydrogenase (LDH) in the serum. The higher expression levels of immunerelated genes were observed in the immune tissues of inoculated grouper compared to the control. In conclusion, ΔfliR effectively improved the immunity of inoculated fish. The results suggest that DfliR is an effective live attenuated vaccine against vibriosis in in grouper. [ABSTRACT FROM AUTHOR]

The online intermediary connects merchants whose products and services it offers, and end-customers who do online shopping through the intermediary, but consume products and services traditionally. Specifically, this study focuses on two purchase processes, namely online transactions, and the retailer experience. Consequently, intermediaries need to know if e-loyalty can be threatened by poor service delivered by the merchants. Our goal is to identify and examine factors that determine e-loyalty towards a groupbuying site as an intermediary. We developed an integrative theoretical model based on the expectation confirmation model positing that satisfaction with the intermediary's eservice and merchants' service has a significant positive impact on e-loyalty towards the intermediary. We use structural equation modelling for evaluating the satisfaction and intentions for loyalty to the intermediary, employing collected survey data of 2.691 responses from Grouper customers. We measure the intermediary's e-service quality using IS scale and we add customer support as an important factor for e-loyalty. The findings suggested that satisfaction with e-service quality significantly affected customers' e‐loyalty towards intermediaries. This study provides insights for intermediaries in identifying e‐loyalty drivers, understanding customers' needs, and improving online performance to maintain satisfied customers who will continue using their services. [ABSTRACT FROM AUTHOR]

Protogynous groupers, belonging to the subfamily Epinephelinae, are among the most crucial fishery targets in the Asian countries. Currently, several grouper species are cultured, providing seed for the aquaculture industry. However, cultivation grouper larvae are unstable. Thus, the improvement of aquaculture technology of grouper production is needed. Appropriate managing the reproduction and sex of the target parent fish is vital to enhance the efficiency of aquaculture. This paper reviews new technologies for induction of gonadal maturation and control of sex in groupers. The dynamics of androgen-producing cells, which are essential for a sex change, are also discussed.

Water quality improvement was carried out by means of recirculation and bioremediation systems in grouper nurseries with high stocking density, thereby increasing production performance. The goal of this study was to evaluate the effectiveness of aquabusiness by analyzing the rise in grouper nursery stocking density using RAS and bioremediation systems. The test parameters consist of production performance, blood glucose levels, physic-chemistry-biology of water quality, and business efficiency based on productivity and business analysis. Treatment of 1,000 fish/m³ increased survival, blood glucose levels, total bacteria, Vibrio spp., ammonia, nitrite, and all productivity parameters. But it lowers all growth parameters, pH, and dissolved oxygen values. The recirculation system with bioremediation at up to 1,000 fish/m³ of stocking boosted the profit by 2.64 times. and 14.97% more efficient than 500 fish/m³ which could not be matched by the high production performance. [ABSTRACT FROM AUTHOR]

Published data were used to model the transfer of ciguatoxins (CTX) across three trophic levels of a marine food chain on the Great Barrier Reef (GBR), Australia, to produce a mildly toxic common coral trout (Plectropomus leopardus), one of the most targeted food fishes on the GBR. Our model generated a 1.6 kg grouper with a flesh concentration of 0.1 µg/kg of Pacific-ciguatoxin-1 (P-CTX-1 = CTX1B) from 1.1 to 4.3 µg of P-CTX-1 equivalents (eq.) entering the food chain from 0.7 to 2.7 million benthic dinoflagellates (Gambierdiscus sp.) producing 1.6 pg/cell of the P-CTX-1 precursor, P-CTX-4B (CTX4B). We simulated the food chain transfer of ciguatoxins via surgeonfishes by modelling Ctenochaetus striatus feeding on turf algae. A C. striatus feeding on ≥1000 Gambierdiscus/cm2 of turf algae accumulates sufficient toxin in <2 days that when preyed on, produces a 1.6 kg common coral trout with a flesh concentration of 0.1 µg/kg P-CTX-1. Our model shows that even transient blooms of highly ciguatoxic Gambierdiscus can generate ciguateric fishes. In contrast, sparse cell densities of ≤10 Gambierdiscus/cm2 are unlikely to pose a significant risk, at least in areas where the P-CTX-1 family of ciguatoxins predominate. The ciguatera risk from intermediate Gambierdiscus densities (~100 cells/cm2) is more difficult to assess, as it requires feeding times for surgeonfish (~4–14 days) that overlap with turnover rates of turf algae that are grazed by herbivorous fishes, at least in regions such as the GBR, where stocks of herbivorous fishes are not impacted by fishing. We use our model to explore how the duration of ciguatoxic Gambierdiscus blooms, the type of ciguatoxins they produce, and fish feeding behaviours can produce differences in relative toxicities between trophic levels. Our simple model indicates thresholds for the design of risk and mitigation strategies for ciguatera and the variables that can be manipulated to explore alternate scenarios for the accumulation and transfer of P-CTX-1 analogues through marine food chains and, potentially, for other ciguatoxins in other regions, as more data become available. [ABSTRACT FROM AUTHOR]

To further clarify the effect of lethal conditions on the quality of grouper(Epinephelus lanceolatus) and to improve the quality of grouper during refrigeration, five different lethal methods were used to treat grouper, with the following groups: Ⅰ: lethal by ice burial; Ⅱ: lethal by knocking on the head; Ⅲ: lethal by subjecting live grouper to temperature gradients of 18, 14, 10 and 6 ℃ (each temperature treatment for 20 min); Ⅳ: lethal by subjecting live grouper to temperature gradients of 18, 12 and 6 ℃ (20 min at each temperature); Ⅴ: lethal by subjecting live grouper to temperature gradients of 18, 6 ℃ (20 min at each temperature). The grouper was then rapidly reduced to 0 ℃ in the centre of the fish body by micro-freezing machine and refrigerated at 0-4 ℃. The effects of changes in the sensory evaluation, textural characteristics, pH, lactic acid content, sulfhydryl content, volatile salt nitrogen (TVB-N), total bacterial colony count and other quality evaluation indicators of the fish during the freezing period were subsequently measured and analyzed. The results showed that the five groups of lethal treatments had significant effects on the quality of fish meat during refrigeration, in descending order: sensory evaluation and TVB-N: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, texture: group Ⅳ> group Ⅴ> group Ⅱ> group Ⅰ> group Ⅲ, lactic acid content and pH: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, sulfhydryl content and total bacterial colony: group Ⅰ> group Ⅱ> group Ⅴ> group Ⅳ> group Ⅲ. > group Ⅳ > group Ⅲ. This indicated that the lethal treatment by gradient cooling was significantly better than the lethal treatment by head knocking and ice burying, and the temperature difference interval in gradient cooling should not be too wide. The results of the quality evaluation of all the indicators showed that group Ⅲ had the best lethal treatment, as the narrower temperature range made the process of grouper death less stressful, and the lactic acid content, pH and total sulfhydryl group were relatively stable, which was more effective than the other four groups in delaying the reduction of textural characteristics and sulfhydryl group content and inhibiting microbial activity, thus prolonging the shelf life of the fish samples. [ABSTRACT FROM AUTHOR]

Vibrio alginolyticus which becomes the main cause of vibriosis disease in grouper culture and causes great economic loss in Asian aquaculture industries. This study investigated the antibacterial activity of clove extract and the effect of adding clove powder to the diet on survival “cantang” hybrid grouper infected with V. alginolyticus. The clove extraction used a maceration method. Two dose levels of clove powder were used, namely 10 and 15 g/kg. The control treatments without clove powder supplementation contained positive control (CP) and negative control treatment (CN). The results found that the clove extract contained five major compounds. The highest compound was phenol, 2-methoxy-4-(2-propenyl)-eugenol (64.07%). Phytochemical analysis of clove extract contained phenolics, flavonoids, and tannins at (28.53 ± 0.00) mg/g, (0.38 ± 0.00) mg/g, and (0.15 ± 0.00) %, respectively. The diameter of the clove extract inhibition zone was significantly different in all treatments. The scanning electron microscopy (SEM) result presents that the clove extract can alter the V. alginolyticus cell morphology. The dietary supplementation of clove powder improves the survival rate significantly higher (P<0.05) post-challenge test. The conclusion of this research is that clove extract has antibacterial activity that can inhibit growth and cause cell morphological damage to V. alginolyticus. The application of clove powder at a dose of 15 g/kg was able to improve the survival value post-challenge test. [ABSTRACT FROM AUTHOR]

Surprisingly, the impacts of environmental changes on the physiology of tropical/subtropical marine fishes have received limited attention. Given that (i) temperature is considered to be a key factor controlling the biology of fishes; (ii) no published data are available on the swimming performance, metabolic capacity or cardiac function of any of the ~165 grouper species worldwide; and (iii) the Nassau grouper is an endangered species of great ecological and socioeconomic significance in The Bahamas, we investigated how current summer/early fall (30°C) and winter (22°C) temperatures in South Eleuthera affected the aerobic metabolism and heart function of wild Nassau grouper when swum to exhaustion (i.e. to their critical swimming speed, U crit). The Nassau grouper had a very low U crit at 30°C (i.e. <1 body lengths s−1), and a 30% lower swimming performance during the winter (at 22°C), and this was that was indicative of a reduced absolute aerobic scope (~185 vs. 290 mg O2 kg−1 h−1) and values of maximum heart rate (⁠|$f$| HMax) and scope for |$f$| H that were only one-half of that achieved at 30°C (~60 vs. 120 and 29 vs. 61 beats min−1, respectively). Overall, these data reveal that the Nassau grouper's aerobic and swimming capacity are well below values reported for other tropical/subtropical fishes and suggest that, despite a compensatory (~30–40%) increase in stroke volume, constraints on |$f$| H near this species' lower thermal limit negatively affect its cardiac output and swimming performance. These findings have considerable ecological implications as Bahamian grouper populations migrate over long distances to spawn during the winter months, and given the predicted increase in temperature variability with climate change. [ABSTRACT FROM AUTHOR]

Natural spawning of the leopard grouper (Mycteroperca rosacea) was studied in captivity from 2004 to 2008 under natural photoperiod conditions. Fish spawned naturally in 2006, but only 90,000 unfertilized eggs were collected. A total of 43 and 27 spawning days were observed in 2007 and 2008, respectively. Spawning season began in March and lasted until May–June and was related to an increase in water temperature from 21.1 to 23.8 °C. The mean (SE) number of eggs released each day was 101,705 (13,876) in 2007 and 40,510 (7,874) in 2008, and the total number of eggs collected in 2007 and 2008 was 4.37 × 106 and 1.07 × 106, respectively. The number of eggs collected per month was not significantly different within each year (P > 0.05), although a significant difference was observed between 2007 and 2008 (P < 0.05). The annual relative number of eggs released was 288,750 eggs·kg–1 in 2007 and 72,919 eggs·kg–1 in 2008, and viable egg production was 184,800 eggs kg–1 in 2007 and 25,375 eggs kg–1 in 2008. The fertilization rate (%) of the eggs collected daily differed significantly throughout the spawning season of 2007 (P < 0.05). The fertilization rate also differed (P < 0.05) between 2007 (61.10%) and 2008 (32.30%). Statistical analysis of the 2 consecutive spawning seasons indicated no correlation between the fertilization rate and fecundity. The effect of the moon phase on spawning was also considered. The fish spawned at dusk before total darkness. Mean (SD) egg diameter was 864.0 ± 22.0 μm.

Managing recreational fisheries requires balancing sustainability against allowing as much access and harvest as possible. Maintaining sustainability is made harder by discard mortality where any fishing activity, even catch and release, risks fish dying from injuries, predation, or other causes. This is especially a problem for Florida reef fish species that live at depths and habitats where barotrauma increases mortality and depredation by larger fish, sharks, or marine mammals increases it further. Harvest (or trip) tags could reduce overharvest, lower discard mortality, and allow anglers more freedom to choose when to fish. Harvest tags would limit the total fish harvested, but could eliminate one of the least popular current management restrictions, harvest seasons. This publication describes harvest tag approaches, discussing how they are already used in fishing and hunting and describing some of the potential benefits and costs if they were applied in Florida.

Signal transducer and activator of transcription 2 (STAT2) is an important molecule involved in the type I interferon signaling pathway. To better understand the functions of STAT2 in fish immune response, a STAT2 gene from orange-spotted grouper (Epinephelus coioides) (EcSTAT2) was cloned and characterized in this study. EcSTAT2 encoded a 802-amino acid peptide which shared 99.5% and 91.5% identity with giant grouper (Epinephelus lanceolatus) and leopard coral grouper (Plectropomus leopardus), respectively. Amino acid alignment analysis showed that EcSTAT2 contained five conserved domains, including N-terminal protein interaction domain, coiled coil domain (CCD), DNA binding domain (DBD), Src-homology 2 (SH2) domain, and C-terminal transactivation domain (TAD). Phylogenetic analysis indicated that EcSTAT2 clustered into fish STAT2 group and showed the nearest relationship to giant grouper STAT2. In healthy grouper, EcSTAT2 was distributed in all tissues tested, and the expression of EcSTAT2 was predominantly detected in spleen, kidney and gill. In vitro, EcSTAT2 expression was significantly increased in response to polyinosinic:polycytidylic acid [poly (I:C)] stimulation and red-spotted grouper nervous necrosis virus (RGNNV) infection. Subcellular localization showed that EcSTAT2 was located in the cytoplasm in a punctate manner. EcSTAT2 overexpression significantly inhibited RGNNV replication, as evidenced by the decreased severity of cytopathic effect (CPE) and the reduced expression levels of viral genes and protein. Consistently, knockdown of EcSTAT2 using small interfering RNA (siRNA) promoted RGNNV replication. Furthermore, EcSTAT2 overexpression increased both interferon (IFN) and interferon stimulated genes (ISGs) expression. In addition, EcSTAT2 knockdown decreased the transcription levels of IFN and ISGs. Together, our data demonstrated that EcSTAT2 exerted antiviral activity against RGNNV through up-regulation of host interferon response. • Identification of a STAT2 (EcSTAT2) homolog from orange-spotted grouper. • Subcellular localization and tissue distribution of EcSTAT2. • Expression pattern of EcSTAT2 in response to poly (I:C) and RGNNV. • EcSTAT2 inhibits RGNNV replication. • EcSTAT2 upregulates IFN and ISGs expression. [ABSTRACT FROM AUTHOR]

In the reproductive season, lunar-synchronized fish spawn during species-specific moon phases. It remains unknown how they perceive cues from the moon for initiating gonadal development and subsequent spawning. We hypothesized that fish use moonlight to synchronize reproductive events. Using the honeycomb grouper Epinephelus merra, a tropical Serranidae, spawns around the time of the full moon, we report the successful induction of spawning in this species by controlling light condition at night. Following 3 months of acclimatization under long days (14:10) at 28 ± 1.0°C, mature fish were reared under an artificial full (experimental group) or new (controls) moon during scotophase. Rearing fish under these conditions for 1 month resulted in successful spawning in the experimental group between 21h00 and 01h30. Similar results were obtained when control fish were subdivided into artificial full and new moon groups and reared for an additional month. Fish in the experimental group had a high gonadosomatic index and abundant yolk-laden oocytes in the ovary. Therefore, moonlight triggers gonadal development and subsequent spawning in lunar-synchronized fish with a full-moon preference. [ABSTRACT FROM AUTHOR]

Cystatin F (CyF), an inhibitor of cysteine protease, was widely studied in immune defense and cancer therapy. However, the function of CyF and its latent molecular mechanism during virus infection in fish remain vacant. In our research, we cloned the open reading frame (ORF) of CyF homology from orange-spotted grouper (Ec-CyF) consisting of 342 nucleotides and encoding a 114-amino acid protein. Ec-CyF included two cystatins family sequences containing one KXVXG sequence without the signal peptide, and a hairpin ring containing proline and tryptophan (PW). Tissue distribution analysis indicated that Ec-CyF was highly expressed in spleen and head kidney. Besides, further analysis showed that the expression of Ec-CyF increased during SGIV infection in grouper spleen (GS) cells. Subcellular localization assay demonstrated that Ec-CyF was mainly distributed in cytoplasm in GS cells. Overexpressed Ec-CyF demoted the mRNA level of viral genes MCP, VP19 and LITAF. Meanwhile, SGIV-induced apoptosis in fat head minnow (FHM) cells was impeded, as well as the restraint of caspase 3/7 and caspase 8. In addition, Ec-CyF overexpression up-regulated the expression of IFN related molecules including ISG15, IFN, IFP35, IRF3, IRF7, MYD88 and down-regulated proinflammatory factors such as IL-1β, IL-8 and TNF-α. At the same time, Ec-CyF-overexpressing increased the activity of IFN3 and ISRE promoter, but impeded NF-κB promoter activity by luciferase reporter gene assay. In summary, our findings suggested that Ec-CyF was involved in innate immunity response and played a key role in DNA virus infection. • Cystatin F gene from Epinephelus coioides (Ec-CyF) was identified and characterized. • Overexpression of Ec-CyF significantly inhibited SGIV infection in GS cells. • Overexpression of Ec-CyF significantly suppressed SGIV-induced apoptosis in FHM cells. • Overexpression of Ec-CyF positively regulated interferon immune response. [ABSTRACT FROM AUTHOR]