Explore the vast range of titles available.

Singapore grouper iridovirus (SGIV) is a virus with high fatality rate in the grouper culture industry. The outbreak of SGIV is often accompanied by a large number of grouper deaths, which has a great impact on the economy. Therefore, it is of great significance to find effective drugs against SGIV. It has been reported that edaravone is a broad-spectrum antiviral drug, most widely used clinically in recent years, but no report has been found exploring the effect of edaravone on SGIV infections. In this study, we evaluated the antiviral effect of edaravone against SGIV, and the anti-SGIV mechanism of edaravone was also explored. It was found that the safe concentration of edaravone on grouper spleen (GS) cells was 50 µg/mL, and it possessed antiviral activity against SGIV infection in a dose-dependent manner. Furthermore, edaravone could significantly disrupt SGIV particles and interference with SGIV binding to host cells, as well as SGIV replication in host cells. However, edaravone was not effective during the SGIV invasion into host cells. This study was the first time that it was determined that edaravone could exert antiviral effects in response to SGIV infection by directly interfering with the processes of SGIV infecting cells, aiming to provide a theoretical basis for the control of grouper virus disease.

(1) Background: Singapore grouper iridovirus (SGIV) can cause extensive fish deaths. Therefore, developing treatments to combat virulent SGIV is of great economic importance to address this challenge to the grouper aquaculture industry. Green tea is an important medicinal and edible plant throughout the world. In this study, we evaluated the use of green tea components against SGIV infection. (2) Methods: The safe working concentrations of green tea components were identified by cell viability detection and light microscopy. Additionally, the antiviral activity of each green tea component against SGIV infection was determined with light microscopy, an aptamer (Q5c)-based fluorescent molecular probe, and reverse transcription quantitative PCR. (3) Results: The safe working concentrations of green tea components were green tea aqueous extract (GTAE) ≤ 100 μg/mL, green tea polyphenols (TP) ≤ 10 μg/mL, epigallocatechin-3-gallate (EGCG) ≤ 12 μg/mL, (-)-epigallocatechin (EGC) ≤ 10 μg/mL, (-)-epicatechin gallate (EGC) ≤ 5 μg/mL, and (-)-epicatechin (EC) ≤ 50 μg/mL. The relative antiviral activities of the green tea components determined in terms of MCP gene expression were TP > EGCG > GTAE > ECG > EGC > EC, with inhibition rates of 99.34%, 98.31%, 98.23%, 88.62%, 73.80%, and 44.31%, respectively. The antiviral effect of aptamer-Q5c was consistent with the results of qPCR. Also, TP had an excellent antiviral effect in vitro, wherein the mortality of fish in only the SGIV-injection group and TP + SGIV-injection group were 100% and 11.67%, respectively. (4) Conclusions: In conclusion, our results suggest that green tea components have effective antiviral properties against SGIV and may be candidate agents for the effective treatment and control of SGIV infections in grouper aquaculture.

This study aimed to investigate the correlation between melatonin and the reproductive mechanism of farmed female red‐spotted groupers, Epinephelus akaara. Through the reproductive cycle experiment, the sexual maturity period was determined to be from June to July, following which the spawning season occurred in August. In addition, kiss1, kiss2, and GPR54 mRNA expression levels peaked in January, whereas that of sbGnRH mRNA remained at high levels from January to May and decreased during the sexual maturity and spawning seasons. During the day–night cycle, a nocturnal rhythm of AANAT2 mRNA expression was observed in the brain, and AANAT2 mRNA expression showed a seasonal pattern with increased expression during summer compared with that in winter. A correlation between melatonin and reproduction‐related genes could not be observed via melatonin administration, and sexual maturity was observed to be more induced under long photoperiod conditions compared with short photoperiod conditions. These results indicate that the reproductive mechanism of the farmed female red‐spotted grouper is related to changes in photoperiod and melatonin, and further research is needed to clarify the reproductive mechanism. Our findings provide basic information for identifying the reproductive mechanisms of farmed E. akaara.

Cholesterol 25-hydroxylase (CH25H) is an interferon (IFN)-induced gene that catalyzes the oxidation of cholesterol to 25-hydroxycholesterol (25HC), which exerts broad-spectrum antiviral function. To investigate the roles of fish CH25H in Singapore grouper iridovirus (SGIV) and red-spotted grouper nervous necrosis virus (RGNNV) infection, we cloned and characterized a CH25H homolog from orange-spotted grouper ( ) (EcCH25H). EcCH25H encoded a 271-amino-acid polypeptide, with 86 and 59% homology with yellow croaker ( ) and humans, respectively. EcCH25H contained a conserved fatty acid (FA) hydroxylase domain and an ERG3 domain. EcCH25H expression was induced by RGNNV or SGIV infection, lipopolysaccharide (LPS) or poly (I:C) treatment . Subcellular localization showed that EcCH25H and mutant EcCH25H-M were distributed in the cytoplasm and partly colocalized with the endoplasmic reticulum. SGIV and RGNNV replication was decreased by EcCH25H overexpression, which was reflected in the reduced severity of the cytopathic effect and a decrease in viral gene transcription, but replication of both viruses was increased by knockdown of EcCH25H. Besides, the antiviral activity was dependent on its enzymatic activity. Treatment with 25HC significantly inhibited replication of SGIV and RGNNV. EcCH25H overexpression positively regulated the IFN-related molecules and proinflammatory cytokines, and increased both IFN and ISRE promoter activities. Moreover, 25HC treatment significantly suppressed SGIV and RGNNV entry into host cells. The similar inhibitory effect on SGIV entry was observed in EcCH25H overexpression cells. Taken together, our findings demonstrated that EcCH25H inhibited SGIV and RGNNV infection by regulating IFN signaling molecules, and might also influence viral entry via an effect on cholesterol.

Singapore grouper iridovirus (SGIV) infection is associated with high mortality in mariculture, and effective treatments are urgently required. Given the wide‐ranging applications of metformin, we aimed to assess the effects of metformin against SGIV. The safe and effective concentration of metformin in grouper spleen cells was determined as 250 μg/mL. We detected the inhibitory activity of metformin against SGIV infection in grouper spleen cells using an aptamer‐based fluorescent molecular probe and reverse transcription‐quantitative real‐time polymerase chain reaction. Metformin effectively inhibited SGIV infection in a dose‐dependent manner and showed an excellent inhibitory effect against SGIV in vitro (70%). We further investigated metformin's possible antiviral mechanism and showed that metformin did not damage SGIV invading host cells, but could damage SGIV particles (59.57%) and interfere with SGIV binding (23.25%) and replication (29.48%) in host cells. Metformin mainly inhibited SGIV by damaging SGIV particles. Overall, these results suggested that metformin had direct and host‐mediated antiviral effects against SGIV and thus had great potential for the development of effective drugs to control SGIV infection in aquaculture.

The original objective was to explore the potential benefiting effects of three prebiotics in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). Therefore, three experimental diets (basal diet + 1% fructooligosaccharide, Diet F; basal diet + 1% inulin, Diet I; basal diet + 0.3% mannan-oligosaccharide, Diet M) and one basal diet (Diet C) were prepared and a feeding trial was conducted. However, at the end of the fourth week into the feeding experiment, a water-leaking accident occurred and fishes of all groups went through an unexpected air exposure event. Surprisingly, different prebiotic-supplemented groups showed significantly different air exposure tolerance: the mortality of M group was significantly lower (P ≤ 0.05) than all the other groups. Examination of antioxidant, non-specific immunity, and stress parameters revealed that comparing to control group, M group showed significantly increased catalase (CAT), acid phosphatase (ACP), and alkaline phosphatase (AKP) activities, decreased superoxide dismutase (SOD) activity, and similar cortisol level (P ≤ 0.05). Real-time PCR experiment revealed that M group significantly increased the expression of CAT, glutathione peroxidase (GPx), and manganese superoxide dismutase (MnSOD) genes in head kidney (P ≤ 0.05). Overall, M exhibited the best anti-air exposure/antioxidative stress effects among the three prebiotics and could be considered a promising feed additive to relieve air exposure/oxidative stress in hybrid grouper culture.

The importance of the temperature tolerance of fish is increasing due to climate change caused by global warming. This study examined the expression of the heat shock protein 70 (HSP70) gene, and plasma cortisol and glucose levels, as a stress response in red-spotted and hybrid groupers during exposure to heat and cold shock. Temperature in the tank where fishes acclimated at 20℃ was gradually increased or decreased, respectively, to examine the survival rate of fish. The result showed a higher survival rate of the hybrid than that of the red-spotted grouper upon exposure to a higher temperature. To further analyze the factors associated with temperature-associated stress, fishes were collected from different temperatures which changed from 20 to 30℃ or 10℃, respectively, and then back to 20℃. The expression levels of the gene encoding heat shock protein 70 (HSP70) were analyzed by qPCR using cDNA prepared from RNA extracted from the brain. A higher level of HSP70 transcript was detected in the hybrid during heat shock exposure. Analysis of cortisol and glucose from the blood of fish collected during the acclimation periods clearly indicated that the level of cortisol was increased upon temperature shift although a slight difference in the degrees of changes timing was slightly different between red-spotted grouper and hybrid. The results showed a correlation between the level of HSP70 and survival rate upon exposure to higher temperature shock. This study provides basic information regarding whether HSP70 expression increases the survival rate of fish subjected to rapid temperature changes.

Groupers are valuable economic fish in the southern sea area of China, but the threat of disease is becoming more and more serious. Vibrio harveyi, V. parahaemolyticus, and Singapore grouper iridovirus (SGIV) are three important pathogens that cause disease in groupers, and infection with either a single one or a mix of these pathogens poses a serious threat to the healthy development of grouper culture. To enhance the rapid diagnosis and screening in the early stages, it is necessary to develop rapid detection methods of these pathogens. To simultaneously and rapidly detect the three pathogens, in this study, we utilized the TolC of V. harveyi, DNAJ of V. parahaemolyticus, and RAD2 of SGIV as the target genes and established a triple visual loop-mediated isothermal amplification (LAMP) method. This LAMP method showed a detection time as fast as 30 min and a high sensitivity of 100 fg/μL. Moreover, this method exhibited strong specificity and no cross-reaction with seven types of Vibrio and Staphylococcus aureus, as well as five common viruses in aquatic animals. Then, the LAMP products were enzymically cut, and three characteristic strips were used to identify the pathogen species. The results of the clinical trials demonstrated that the method could accurately and specifically detect V. harveyi, V. parahaemolyticus, and SGIV in grouper tissues. In summary, this study successfully established a triple visual LAMP rapid detection method for V. harveyi, V. parahaemolyticus, and SGIV. The method offers several advantages including simple equipment, easy operation, rapid reaction, high specificity, high sensitivity, and visual results. It is suitable for the early and rapid diagnosis of groupers infected with V. harveyi, V. parahaemolyticus, and SGIV, thereby providing useful technical support for further application in the large-scale disease surveillance of aquaculture animals.

Regional abundances of Nassau grouper Epinephelus striatus and yellowfin grouper Mycteroperca venenosa have declined due to overfishing of their spawning aggregations, prompting permanent and seasonal fisheries closures in the US Virgin Islands (USVI). As both species produce sounds associated with reproductive behaviors (courtship-associated sounds; CAS), passive acoustic and acoustic telemetry methods were used to determine temporal patterns of reproductive activity, site usage, and fish movements in order to assess the effectiveness of current management strategies at 2 marine protected areas (MPAs) in the USVI: the Grammanik Bank (GB) and Hind Bank Marine Conservation District (MCD). Patterns of sound production and ultrasonic acoustic tag detections showed that both species formed spawning aggregations from January through May at the GB, highlighting the current seasonal regulations (1 February to 30 April) as insufficient for protecting spawning stocks during the entire reproductive season. Acoustic tagging confirmed connectivity between the GB and MCD and exposed the broad extent of habitat used, including non-protected areas, during the spawning season. Spawning did not likely occur within the MCD, but the MPA did support abundances of calling individuals during spawning periods, indicating that both species produce CAS away from their spawning sites. This finding coupled with the detection of routine migrations between spawning and non-spawning sites presents a potential mechanism to lead conspecifics to the aggregation site and thereby increase reproductive fitness and spawning output.

Grouper aquaculture is a rapidly growing and dynamic industry within the Taiwan aquaculture sector that serves as an important source of income generation. Farming fishes at a better location (FFABL) is a promising production strategy. This study evaluated the production and economic performance of grouper farming in Taiwan. This investigation employed two steps: (1) a cost–benefit analysis to determine the main component affecting profitability; and (2) multivariate statistics to clarify the relationship between biological and economic factors. The findings suggest that the best choice of species is hybrid giant grouper that generates and highlights a positive income, viable benefit–cost ratio and profit rate. The study found the feed management of hybrid giant groupers requires more consideration due to its low feed conversion ratio. The producers need to replace trash fish in commercial feed during the production cycle to ensure better feed management. Finally, this paper argues that feed is the main constraint for grouper farming, which is sensitive to any change in feed productivity, and this constraint must be solved to sustain the grouper industry in Taiwan.