Aquaculture Industry Research Articles

Leader RNA facilitates snakehead vesiculovirus (SHVV) replication by interacting with CSDE1 and hnRNP A3

Leader RNAs are viral small non-coding RNAs that has been proved to play important roles in viral replication. Snakehead vesiculovirus (SHVV) is an aquatic virus that has caused huge economic loss in Chinese snakehead fish aquaculture industry. It has been proved that SHVV would generate leader RNA during the process of infection, and leader RNA could interact with viral nucleoprotein to promote viral replication. In this study, we identified that leader RNA could also interact with cellular protein Cold Shock Domain containing E1 (CSDE1) and heterogeneous nuclear ribonucleoproteins A3 (hnRNP A3). Further investigation reveals that overexpression of CSDE1 and hnRNP A3 facilitated SHVV replication. Downregulation of CSDE1 and hnRNP A3 by siRNA inhibited SHVV replication. This study provided a new sight into understand the mechanism of SHVV replication, and a potential anti-SHVV target for drug research.

Source elimination of antibiotic resistance risk in aquaculture water by VUV/sulfite pretreatment

Antibiotic resistance risk in the aquaculture industry is increasing with the excessive consumption of antibiotics. Although various efficient technologies for the degradation of antibiotics are available, the potential risk from antibiotic resistance in treated waters is often overlooked. This study compared the risks of antibiotic resistance in anaerobic sludge fed with pretreated florfenicol (FLO) containing wastewater after four UV or vacuum UV (VUV)-driven ((V)UV-driven) pretreatments, and established the VUV/sulfite recirculating water system to validate the effect of controlling the antibiotic resistance risk in the actual aquaculture water. Metagenomics sequencing revealed that a remarkable decrease in the abundance of antibiotic resistance genes (ARGs) was observed in four different pretreated groups, and results among the four pretreated groups were sorted in descending order based on ARG abundance: UV > VUV > UV/sulfite > VUV/sulfite. The low abundance of ARGs from VUV/sulfite group was close to that in the CK group (wastewater without FLO and without any pretreatments), which was 0.41 copies/cell. From the perspective of the temporal changes in the relative abundance of floR, the abundance in VUV/sulfite group remained lower than 11.67 ± 0.73 during the cultivation time. Additionally, microbial diversity analysis found that Proteobacteria and Firmicutes were major carriers of ARGs. Two species from Burkholderiaceae and Rhodocyclales were identified as potential co-hosts to spread by the correlation analysis of the abundances between floR or intI1 and the top 50 genera. Finally, the abundances of ARGs and MGEs in the VUV/sulfite recirculating water system with actual aquaculture water were reduced by 39.15% and 46.04%, respectively, compared to that in the blank group without any pretreatment. This study verified that VUV/sulfite pretreatment system could effectively control the antibiotic resistance risk of ARGs proliferation and transfer in aquaculture water. Furthermore, the study demonstrated that the reduction of antibiotic antibacterial activity plays an important role in the source control of resistance risk.

Effects of dietary primary bile acids on the growth, intestinal morphology, gene expression, serum metabolites and intestinal microbiota in pearl gentian grouper fed a high lipid diet

The grouper aquaculture industry flavors high lipid diets for economic reasons, yet this inevitably produces negative effects on the growth performance and intestinal function. Bile acids have been extensively reported to mitigate the negative effects on fish fed a high lipid diet, but it remains unclear whether this mechanism is bile acid type dependent. Therefore, an eight-week feeding trial was conducted to investigate the response of growth and intestinal health parameters in pearl gentian grouper Epinephelus fuscoguttatus♂ × E. lanceolatus♀ fed with high lipid diets to different types of bile acids. A high lipid diet (diet HL) containing 167 g/kg crude lipid served as the control diet, and three of primary bile acids glycocholic acid, taurocholic acid, and cholic acid were added at a dose of 900 mg/kg to generate the bile acid diets HBG, HBT, and HBC, respectively. Results revealed that dietary supplementation with glycocholic acid, taurocholic acid, or cholic acid does not affect the feed intake and growth of pearl gentian grouper fed a high lipid diet, while increasing the relative abundance of intestinal opportunistic pathogens such as Staphylococcus and Pseudomonas in this species. Dietary supplementation with glycocholic acid or cholic acid decreases muscle layer thickness and villus height, while increases intestinal injury score. Grouper fed with taurocholic acid showed higher villus width and serum antioxidant enzyme activity, along with lower intestinal injury score and serum lipid peroxidation level. For the protein and gene involved in the PI3K/AKT/mTOR pathways, S6K1 signaling, and bile acids metabolism, grouper fed with taurocholic acid exhibited an increase in the protein expression of PP70 and the mRNA expression of nrf2, pi3k, pdk1, tsc2, akt, mtorc1, fxr and tgr5. Moreover, the serum metabolites can be significantly influenced by the intestinal bacteria. Overall, dietary supplementation of 900 mg/kg taurocholic acid is recommended when feeding high lipid diets to grouper.

Advancements in rapid diagnostics and genotyping of Piscirickettsia salmonis using Loop-mediated Isothermal Amplification.

Piscirickettsia salmonis, the causative agent of Piscirickettsiosis, poses a significant threat to the Chilean aquaculture industry, resulting in substantial economic losses annually. The pathogen, first identified as specie in 1992, this pathogen was divided into two genogroups: LF-89 and EM-90, associated with different phenotypic mortality and pathogenicity. Traditional genotyping methods, such as multiplex PCR, are effective but limited by their cost, equipment requirements, and the need for specialized expertise. This study validates Loop-mediated Isothermal Amplification (LAMP) as a rapid and specific alternative for diagnosing P. salmonis infections. We developed the first qPCR and LAMP assay targeting the species-conserved tonB receptor gene (tonB-r, WP_016210144.1) for the specific species-level identification of P. salmonis. Additionally, we designed two genotyping LAMP assays to differentiate between the LF-89 and EM-90 genogroups, utilizing the unique coding sequences Nitronate monooxygenase (WP_144420689.1) for LF-89 and Acid phosphatase (WP_016210154.1) for EM-90. The LAMP assays demonstrated sensitivity and specificity comparable to real-time PCR, with additional benefits including rapid results, lower costs, and simplified operation, making them particularly suitable for field use. Specificity was confirmed by testing against other salmonid pathogens, such as Renibacterium salmoninarum, Vibrio ordalii, Flavobacterium psychrophilum, Tenacibaculum maritimum, and Aeromonas salmonicida, with no cross-reactivity observed. The visual detection method and precise differentiation between genogroups underscore LAMP's potential as a robust diagnostic tool for aquaculture. This advancement in the specie detection (qPCR and LAMP) and genotyping of P. salmonis represents a significant step forward in disease management within the aquaculture industry. The implementation of LAMP promises enhanced disease surveillance, early detection, and improved management strategies, ultimately benefiting the salmonid aquaculture sector.

Isolation, Identification and Genomic Analysis of Orange-Spotted Grouper Iridovirus Hainan Strain in China.

The orange-spotted grouper (Epinephelus coioides) is an important mariculture fish in China. However, in recent years, with the rapid development of aquaculture activities, outbreaks of viral diseases have affected the grouper aquaculture industry, causing severe economic losses. In the present study, we isolated and identified a virus from diseased, orange-spotted groupers from an aquaculture farm in Hainan Province, China. The isolated virus was identified as orange-spotted grouper iridovirus, hence named the orange-spotted grouper iridovirus Hainan strain (OSGIV-HN-2018-001). OSGIV-HN-2018-001 induces a cytopathic effect after the infection of mandarin fish (Siniperca chuatsi) brain clonal passage (SBC) cells. In addition, the cytoplasm of the OSGIV-HN-2018-001-infected SBC cells was found to contain a large number of hexagonal virus particles with a diameter of approximately 134 nm. Using the Illumina NovaSeq system, we assembled the sequence data and annotated the complete genome of OSGIV-HN-2018-001 (GenBank accession number: PP974677), which consisted of 110,699 bp and contained 122 open reading frames (ORFs). Phylogenetic tree analysis showed that OSGIV-HN-2018-001 was most closely related to ISKNV-ASB-23. The cumulative mortality rate of groupers infected with OSGIV-HN-2018-001 reached 100% on day 8. The spleens were enlarged and blackened after the dissection of the dying groupers. These results contribute to the understanding of the molecular regulatory mechanism of the iridovirus infection and provide a basis for iridovirus prevention.

Luteolin-borneol complex, a novel pharmaceutical preparation for aquaculture against NNV infection

Nervous necrosis virus poses a significant challenge to the aquaculture industry, resulting in substantial financial losses globally. In this study, we evaluated the anti-NNV activity of luteolin, a flavonoid natural product. The results demonstrated that luteolin, at a concentration of 27.95 μM, significantly inhibited NNV-induced cytopathic effects. Additionally, the half-inhibitory concentration for luteolin against NNV replication was determined to be 9.87 μM. Importantly, luteolin was shown to inhibit NNV proliferation by suppressing NNV-induced late apoptosis. Furthermore, luteolin demonstrated a preventive effect against NNV infection. To enhance the in vivo antiviral efficacy of luteolin and address the selective permeability of the blood-brain barrier (BBB), we prepared a luteolin-borneol complex. The presence of borneol significantly enhanced the in vivo antiviral activity of luteolin, likely due to its ability to improve BBB permeability, thereby enhancing luteolin's bioavailability. These findings suggested that luteolin is a potent anti-NNV agent, and that the luteolin-borneol complex represented a novel therapeutic approach with promising applications for combating NNV infections.

Longline and mesocosm cultivation of serrated wrack Fucus serratus (Phaeophyceae)

ABSTRACT Seaweed aquaculture is becoming increasingly important as the global seaweed market is set to exceed £20 billion by 2030, leaving natural populations at risk of overexploitation. Fucoids, such as Fucus serratus, are intertidal seaweeds hand-harvested for their use in agricultural, pharmaceutical, and biomedical industries. Despite many aspects of the biology of fucoids being well researched, there have been very few studies on their aquaculture. In this study, we grew F. serratus biomass from gamete life stages in the Queen’s University Marine Laboratory for 8 months and monitored their growth, amino acid and phenolic contents in a subtidal field trial. Gametes of F. serratus were successfully fertilized in vitro and attached to substrata: Tiles (mesocosm) and Dyneema Twine (subtidal). The growth of F. serratus on each substrate was monitored for 6 months in the laboratory facility with juveniles reaching 2–4 mm in length. The juveniles on twine were then deployed at the Strangford Lough test site and growth was compared against the juveniles on tiles after an additional two months. Prior to field deployment, individuals grown on tiles were significantly longer (~17%) than those on twine growing to ~3 cm, however, after the two-month deployment, the twine thalli grew significantly longer than those on the tiles (~33%) reaching ~6 cm in length. Subtidal F. serratus grown on twine had significantly higher amino acid content, whereas the phenolic content was significantly lower (~62 mg PGE g−1) than seaweed grown on the tiles (~128 mgPGE g−1). Growing F. serratus successfully in subtidal areas is highly important for providing sustainably sourced biomass to reduce reliance on wild harvesting. Further, cultivating in the subtidal zone will help to avoid competition for space from other aquaculture industries operating in the intertidal zone.

Temperature-dependent alterations in the proteome of the emergent fish pathogen Edwardsiella piscicida.

Edwardsiella piscicida is an emerging bacterial pathogen and the aetiological agent of edwardsiellosis among cultured and wild fish species globally. The increased frequency of outbreaks of this Gram-negative, facultative intracellular pathogen pose not only a threat to the aquaculture industry but also a possible foodborne/waterborne public health risk due to the ill-defined zoonotic potential. Thus, understanding the role of temperature on the virulence of this emerging pathogen is essential for comprehending the pathogenesis of piscine edwardsiellosis in the context of current warming trends associated with climate change, as well as providing insight into its zoonotic potential. In this study, significant temperature-dependent alterations in bacterial growth patterns were observed, with bacterial isolates grown at 17°C displaying higher peak growth sizes, extended lag times, and slower maximal growth rates than isolates grown at 27or 37°C. When E. piscicida isolates were grown at 37°C compared to 27 and 17°C, mass spectrometry analysis of the E. piscicida proteome revealed significant downregulation of crucial virulence proteins, such as Type VI secretion system proteins and flagellar proteins. Although invivo models of infection are warranted, this invitro data suggests possible temperature-associated alterations in the virulence and pathogenic potential of E. piscicida in poikilotherms and homeotherms.

Impact of Chaetomorpha aerea-enriched diet on growth, feed utilization, and haemato-immunological responses in Clarias batrachus challenged with Aeromonas hydrophila

The bacteria Aeromonas hydrophila, which causes motile Aeromonas septicemia (MAS), is dangerous to aquaculture because it affects the fish's well-being and production. As the aquaculture industry seeks sustainable and effective methods to enhance fish immunity and growth, natural supplements such as marine algae have gained attention. This study explored the potential benefits of incorporating the green marine algae Chaetomorpha aerea into the fish diet, focusing on disease resistance, growth, feed utilization, and hematological and immunological responses. Five diets were prepared, varying concentrations of C. aerea (0 control, T1: 1 g/kg; T2: 2 g/kg: T3: 5 g/kg: and T4: 10 g/kg) and administered to fish over 30 days. Following the feeding trial, the fish were exposed to A. hydrophila, and their survival rates were observed for the next 14 days. The findings demonstrated that the final weight, weight gain, relative growth rate, specific growth rate, and daily growth rate were all positively impacted by a diet containing 5 g/kg of C. aerea. Additionally, fish in the 5 g/kg C. aerea group demonstrated improved feed conversion efficiency compared to the control group. While there were no significant changes in red and white blood cell counts on the initial day, serum lysozyme activity and overall resistance to infection were enhanced in fish receiving C. aerea at 2 and 5 g/kg. These results imply that C. aerea supplementation with fish supplements may be a useful immunostimulant, boosting improved health and growth in sustainable aquaculture practices.

Development of an image binarization software tool for net occlusion estimations

Marine biofouling poses a set of challenges to the salmon aquaculture industry, where an accumulation of biota on pens can lead to significant net mesh occlusion. This can reduce flow rates, risking oxygen depletion. The industry currently manages this challenge through regular cleaning of nets, with sporadic manual visual estimations of net occlusion an important but time-consuming task. This study developed a simple automated desktop application to more regularly and more robustly quantify pen net occlusion caused by biofouling. This software application pre-processes and binarizes images collected from cameras currently used by the industry into water and non-water pixels. The percentage of net occlusion is then calculated from the binary image. Accurate binarization of representative images was achieved by training a deep learning network on images collected in situ. The resulting network attained a validation accuracy of 96.4 % and a mean test accuracy of 93.5 %. From the test images, 98.3 % of pixels annotated as non-water and 88.8 % of pixels annotated as water were correctly classified by the network. This automated tool has the capacity to better inform industry and create a more efficient cleaning framework based on the needs of individual pens, based on data that can be more readily obtained as compared to manual net inspections.

Nectin1 is a pivotal host factor involved in attachment and entry of red-spotted grouper nervous necrosis virus in the early stages of the viral life cycle.

Nervous necrosis virus (NNV) is a highly neurotropic virus that poses a persistent threat to the survival of multiple fish species. However, its inimitable neuropathogenesis remains largely elusive. To rummage potential partners germane to the nervous system, we investigated the interaction between red-spotted grouper NNV (RGNNV) and grouper brain by immunoprecipitation coupled with mass spectrometry and discerned Nectin1 as a novel host factor subtly involved in viral early invasion events. Nectin1 was abundant in neural tissues and implicated in the inception of tunnel nanotubes triggered by RGNNV. Its overexpression not only dramatically potentiated the replication dynamics of RGNNV in susceptible cells, but also empowered non-sensitive cells to expeditiously capture free virions within 2 min. This potency was impervious to low temperatures but was dose-dependently suppressed by soluble protein or specific antibody of Nectin1 ectodomain, indicating Nectin1 as an attachment receptor for RGNNV. Mechanistically, efficient hijacking of virions by Nectin1 strictly depended on intricate linkages to different modules of viral capsid protein, especially the direct binding between the IgC1 loop and P-domain. More strikingly, despite abortive proliferation in Nectin1-reconstructed CHSE-214 cells, a non-sensitive cell, RGNNV could gain access to the intracellular compartment by capitalizing on Nectin1, thereby inducing canonical cytoplasmic vacuolation. Altogether, our findings delineate a candidate entrance for RGNNV infiltration into the nervous system, which may shed unprecedented insights into the exploration and elucidation of RGNNV pathogenesis.IMPORTANCENervous necrosis virus (NNV) is one of the most virulent pathogens in the aquaculture industry, which inflicts catastrophic damage to ecology, environment, and economy annually around the world. Nevertheless, its idiosyncratic invasion and latency mechanisms pose enormous hardships to epidemic prevention and control. In this study, deploying grouper brain as a natural screening library, a single-transmembrane glycoprotein, Nectin1, was first identified as an emergent functional receptor for red-spotted grouper NNV (RGNNV) that widely allocated in nervous tissues and directly interacted with viral capsid protein through distinct Ig-like loops to bridge virus-host crosstalk, apprehend free virions, and concomitantly propel viral entry. Our findings illuminate the critical role of Nectin1 in RGNNV attachment and entry and provide a potential target for future clinical intervention strategies in the therapeutic race against RGNNV.

Liquid-liquid phase separation is essential for reovirus viroplasm formation and immune evasion.

Grass carp reovirus (GCRV) poses a significant threat to the aquaculture industry, particularly in China, where grass carp is a vital commercial fish species. However, detailed information regarding how GCRV viroplasms form and their specific roles in GCRV infection remains largely unknown. We discovered that GCRV viroplasms exhibit liquid-like properties and are formed through a physico-chemical biological phenomenon known as liquid-liquid phase separation (LLPS), primarily driven by the nonstructural protein NS80. Furthermore, we confirmed that the liquid-like properties of viroplasms are essential for virus replication, assembly, and immune evasion. Our study not only contributes to a deeper understanding of GCRV infection but also sheds light on broader aspects of viroplasm biology. Given that viroplasms are a universal feature of reovirus infection, inhibiting LLPS and then blocking viroplasms formation may serve as a potential pan-reovirus inhibition strategy.

Phaeobacter italicus JN-W1: A pathogenic bacterium causing bleaching disease in Porphyra sensu lato (Bangiales, Rhodophyta)

The recent emergence of bleaching disease in the shell-borne conchocelis (SBC) of Porphyra sensu lato has escalated with alarming speed, inflicting severe economic losses on the Porphyra aquaculture industry. Despite the severity of the outbreak, the causative agents of this disease have remained elusive. In this study, we successfully isolated and purified the pathogenic bacterium JN-W1 from SBC affected by bleaching disease. Our infection assays revealed that the bacterium induced the degradation of algal cell organelles and the formation of autophagosomes, ultimately leading to the conversion of dead cells into empty-walled remnants, likely accounting for the bleaching symptoms observed in Porphyra. Additionally, the infection caused severe impairment of the algal photosynthetic apparatus, evidenced by a marked reduction in photosynthetic efficiency as the infection advanced. Through a combination of single-copy orthologous gene analysis and detailed morphological, physiological, and biochemical characterization, strain JN-W1 was definitively classified as Phaeobacter italicus JN-W1. The bacterium demonstrated optimal growth and infection capabilities at 25 °C, pH 7.0, and a salinity of 20. JN-W1's pathogenicity was found to be contact-dependent, mediated by intracellular substances. This study laid a crucial foundation for further exploration of JN-W1's virulence mechanism and the development of effective strategies to prevent and control the outbreaks of Porphyra bleaching disease.

The Liver-Protective Effects of the Essential Oil from Amomum villosum in Tilapia (Oreochromis niloticus): Antioxidant, Transcriptomic, and Metabolomic Modulations.

This study investigates the effects of the essential oil from Amomum villosum (EOA) on liver-protective effects in Nile tilapia (Oreochromis niloticus), utilizing a multidisciplinary approach that integrates physiological assessments and transcriptomic and metabolomic analyses. Fish were fed diets containing 2 g/kg of EOA over a 56-day trial, with a no-EOA diet serving as the control. The results demonstrate that EOA supplementation improves liver histology, enhances antioxidant capacities, and reduces inflammation in tilapia. The transcriptomic analysis revealed significant alterations in gene expression profiles related to RNA splicing, metabolism, and disease pathways. The identification of differential genes and disease databases identified key target genes associated with the primary component of EOA for its anti-hepatobiliary disease effects. Furthermore, a molecular docking analysis of EOA major components with core differentially expressed genes in the hepatobiliary syndrome indicated that α-pinene is a potential Hsp90 inhibitor, which may prevent inflammation. A metabolomic analysis further demonstrated that EOA supplementation leads to notable changes in liver phospholipids, fatty acids, and carbohydrate metabolism. These findings underscore the potential of EOA as a natural additive for improving liver health in tilapia, offering valuable insights to the aquaculture industry for enhancing fish health and welfare in intensive farming systems.

Climate resilience in aquaculture: A cluster analysis of Chinese coastal regional production and farming practices in the face of climatic shifts 2017–2021

This study conducts a comprehensive analysis of the aquaculture industry across 11 coastal regions in eastern China from 2017 to 2021 to assess their adaptability and resilience in the face of climate change. Cluster analysis was employed to examine regional variations in aquaculture adaptation by analyzing data on annual average temperatures, annual extreme high/low temperatures, annual average relative humidity, annual sunshine duration, and total yearly precipitation alongside various aquaculture practices. The findings reveal that southern regions, such as Fujian and Guangdong, demonstrate higher adaptability and resilience due to their stable subtropical climates and advanced aquaculture technologies. In contrast, northern regions like Liaoning and Shandong, characterized by more significant climatic fluctuations, exhibit varying degrees of cluster changes, indicating a continuous need to adjust aquaculture strategies to cope with climatic challenges. Additionally, the study explores the specific impacts of climate change on species selection, disease management, and water resource utilization in aquaculture, emphasizing the importance of developing region-specific strategies. Based on these insights, several strategic recommendations are proposed, including promoting species diversification, enhancing disease monitoring and control, improving water quality management techniques, and urging governmental support for policies and technical guidance to enhance the climate resilience and sustainability of the aquaculture sector. These strategies and recommendations aim to assist the aquaculture industry in addressing future climate challenges and fostering long-term sustainable development.

Investigating the Effect of Bacilli and Lactic Acid Bacteria on Water Quality, Growth, Survival, Immune Response, and Intestinal Microbiota of Cultured Litopenaeus vannamei.

Shrimp is one of the most important aquaculture industries. Therefore, we determined the effect of nitrifying-probiotic bacteria on water quality, growth, survival, immune response, and intestinal microbiota of Litopenaeus vannamei cultured without water exchange. In vitro, only Bacillus licheniformis used total ammonia nitrogen (TAN), nitrites, and nitrates since nitrogen bubbles were produced. TAN decreased significantly in the treatments with B. licheniformis and Pediococcus pentosaceus and Leuconostoc mesenteroides, but no differences were observed in nitrites. Nitrates were significantly higher in the treatments with bacteria. The final weight was higher only with bacilli and bacilli and LAB treatments. The survival of shrimp in the bacterial treatments increased significantly, and superoxide anion increased significantly only in lactic acid bacteria (LAB) treatment. The activity of phenoloxidase decreased significantly in the treatments with bacteria compared to the control. Shrimp treated with bacilli in the water showed lower species richness. The gut bacterial community after treatments was significantly different from that of the control. Linoleic acid metabolism was positively correlated with final weight and superoxide anion, whereas quorum sensing was correlated with survival. Thus, bacilli and LAB in the water of hyperintensive culture systems act as heterotrophic nitrifers, modulate the intestinal microbiota and immune response, and improve the growth and survival of shrimp. This is the first report on P. pentosaceus and L. mesenteroides identified as nitrifying bacteria.

Functional allocation of Mitogen-activated protein kinases (MAPKs) unveils thermotolerance in scallop Argopecten irradians irradians

Global warming has significantly impacted agriculture, particularly in animal husbandry and aquaculture industry. Rising ocean temperatures due to global warming are severely affecting shellfish production, necessitating an understanding of how shellfish cope with thermal stress. The mitogen-activated protein kinases (MAPK) signaling pathway plays a crucial role in cell growth, differentiation, adaptation to environmental stress, inflammatory response, and managing high temperature stress. To investigate the function of MAPKs in bay scallops, a comparative genomics and bioinformatics approach identified three MAPK genes: AiERK, Aip38, and AiJNK. Structural and phylogenetic analyses of these proteins were conducted to determine their evolutionary relationships. Spatiotemporal expression patterns were examined at different developmental stages and in various tissues of healthy adult scallops. Additionally, the expression regulation of these genes was studied in selected tissues (hemocyte, gill, heart, mantle) following exposure to high temperatures (32 °C) for different durations (0 h, 6 h, 12 h, 24 h, 3 d, 6 d, 10 d). The spatiotemporal expressions of AiMAPKs were ubiquitous, with significant increases in AiERK expression observed at the umbo larval stage (3.09-fold), while Aip38 and AiJNK were identified as potential maternal effect genes. In adult scallops, different gene expression patterns of AiMAPKs were observed across eight tissues, with high expressions in the foot and gill, and lower expressions in the striated muscle. Following high temperature stress, AiMAPKs expressions in the gill and mantle were mainly up-regulated, while in the hemocyte, they were primarily down-regulated. These findings indicate time- and tissue-dependent expression patterns with functional allocation in response to different thermal durations. This study enhances our understanding of the function and evolution of AiMAPKs genes in shellfish and provides a theoretical basis for elucidating the energy regulation mechanism of bay scallops in response to high temperature stress.

Genomic evaluation for body weight, length and growth estimates in meagre Argyrosomus regius

Meagre (Argyrosomus regius) is a fast-growing sciaenid species which recently received a rising interest in aquaculture diversification and industry sustainability. The present study illustrates the first complete genomic evaluation of meagre for body weight, length and growth parameters using 810 offspring genotyped with a double-digest RAD sequencing approach. Offspring were assigned to both parents using SNP markers and a QTL associated with growth explaining approximately 3.25 % of the phenotypic variance was found. Using pedigree and genomic relationship matrix, moderate to high heritability estimates along with high genetic/genomic correlations between all studied traits were detected with the exception of the initial body weight. The predicted ability of the breeding values was higher using the genomic than the pedigree relationship matrix for body weight and growth. Present findings provide a better genetic insight of the production traits, as well as evidence that the implementation of the genomic information in breeding programs could be beneficial for the parental assignment as well as for the aquaculture production increase through genetic improvement using marker assisted or genomic selection.

Propagation of koi herpesvirus using embryonated chicken eggs: a potential substitute method for fish vaccine production?

Koi herpesvirus disease (KHVD) is caused by a large DNA virus that commonly infects carp, Cyprinus carpio (koi and common carp). KHVD has spread rapidly across the globe and caused high mortality in all ages of common carp and koi. Until now, no effective treatment has been applied to prevent KHV infection impacting the mass production of koi and common carp . An environmentally friendly alternative strategy for controlling fish disease is vaccination. One of the challenges facing conventional viral vaccine production is the requirement for koi or common carp cell cultures, which must be frequently maintained with expensive materials required for virus propagation. This study aims to obtain KHV that has been propagated in embryonated chicken eggs (ECE) to formulate an affordable KHV vaccine for the aquaculture industry. This research consisted of three stages; the first stage was virus inoculation into various parts of eggs (allantoic fluid, chorioallantoic membrane, amniotic fluid, and egg yolk). The second stage was observing viral growth and collecting ECE fluid and membranes. The third stage involved quantitatively determining the viral genomic copy numbers using the quantitative Polymerase Chain Reaction (qPCR) assay. KHV propagation in various parts of ECE resulted in varying viral genomic copy numbers with a high DNA copy number reported in allantoic fluid on the third day after inoculation. Further work is required to monitor virus titer in later passages and optimize methodology for using ECE as the potential alternative to cultured cells as the medium for virus propagation. In the future the system could be developed to produce promising vaccine candidates with more affordable vaccine prices for the Indonesian fish farming industry.

Transcriptomic analysis provides insights into the mechanisms underlying the resistance of Penaeus vannamei to Enterocytozoon hepatopenaei (EHP)

The Penaeus vannamei aquaculture industry is facing a significant challenge in the form of hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP), resulting in substantial economic losses. However, the extent of knowledge regarding the mechanisms by which shrimp resist EHP is limited. We screened resistant and susceptible shrimp and found that resistant shrimp had lower EHP load and less tissue damage. To gain insight into the molecular mechanisms underlying the EHP resistance of shrimp, a comparison was conducted at the transcriptional level between the resistant and susceptible families. Transcriptomic analysis of shrimp hepatopancreas revealed significant differences between the resistant and susceptible families. Compared to the susceptible family, the immune system of the resistant family was activated. The resistant family showed up-regulation in the expression of cathepsin L, C-type lectin, penaeidin, chitinase genes, and metabolism of xenobiotics by cytochrome P450-related genes. Additionally, the resistant shrimp exhibited a higher capacity for amino acid uptake. The observed differences in the resistant and susceptible family transcriptome may contribute to the shrimp's resistance to EHP.