Bivalve breeding programs account for over 50% of global marine aquaculture, and growth is one of the most important traits of them. With the purpose of investigating the key genes related to growth performance of Yesso scallop (Patinopecten yessoensis), an economically important bivalve, we conducted transcriptome comparison between fast- and slow-growing individuals, and identified 1,531 differentially expressed genes (DEGs), with 656 up-regulated in fast-growing scallops, categorizing into six molecular function terms, of which the thyroxine 5'-deiodinase activity term exhibited the lowest p values. This term contained only two genes, and they were both type I iodothyronine deiodinase (D1), the enzyme catalyzing triiodothyronine (T) production in vertebrates. Meanwhile, T concentration was significantly higher in fast-growing scallops. To further understand D1 functions in bivalve growth, RNA interference (RNAi) was performed in the dwarf surf clam (Mulinia lateralis), a suitable bivalve for verifying the function of growth-related genes. Suppression of MlD1-1 and MlD1-2 expression was detected after RNAi, and in MlD1-1 RNAi group, dwarf surf clams exhibited significant reductions in growth, with shell length, shell width, shell height, and body weight decreasing by 9%, 9%, 9%, and 25%, respectively. Furthermore, the triiodothyronine (T) and thyroxine (T) levels of clams in MlD1-1 RNAi group were significantly decreased by 11% and increased by 5%, respectively, while no changes were observed in the MlD1-2 RNAi group. Our data imply that bivalve D1 could be a candidate gene for the breeding of fast-growing bivalve.

DOPA decarboxylase (DDC) plays a crucial role in the physiological functions of animals by participating in the dopaminergic system. However, the functions of DDC in shellfish remain poorly understood. The Pacific oyster (Crassostrea gigas) is an extensively cultivated shellfish. In this study, we characterized a DDC gene, designated CgDDC, from C. gigas. The CgDDC gene encodes a protein that contains a Pyridoxal_deC domain, which features specific binding sites for pyridoxal-5'-phosphate (PLP) and L-DOPA. CgDDC exhibits a significantly higher expression level in the black shell oyster strain than the white strain. In vitro enzymatic reaction assays demonstrated that CgDDC catalyzes the conversion of L-DOPA to dopamine. In vivo experiments revealed that inhibiting CgDDC activity reduced the expression of genes associated with tyrosine metabolism. Furthermore, the knockdown of CgDDC caused a decline in cAMP level and reduced transcription of genes involved in the cAMP-mediated melanogenesis. Additionally, treatment with L-α-DOPA inhibited CgDDC enzyme activity and cAMP-mediated melanogenesis; however, dopamine supplementation countered this inhibition, maintaining gene expression and melanin content at baseline levels. Collectively, our findings suggest that CgDDC is intricately involved in regulating tyrosine metabolism and melanogenesis in C. gigas.

Coral reefs are essential for biodiversity and ecosystem services, yet they face threats like bleaching and reduced resilience due to rising seawater temperatures and land-based pollution. This study examined phosphate accumulation in calcareous sediments and its relationship with coral populations in Sekisei Lagoon, Okinawa Islands, Japan. Sediment samples from 117 sites were analyzed for exchangeable phosphate in seawater (EPS), which could be released from the calcareous sediments. The EPS levels were negatively correlated with coral densities for adults (Pocillopora, Acropora, Galaxea, Favia, Favites, Goniastrea, and Cyphastrea) and juveniles (Pocillopora, Montipora, Acropora, Galaxea, Favia, Favites, and Goniastrea). No significant correlation was found for Porites or Millepora. The EPS levels were positively correlated with coral bleaching and the abundance of Sargassaceae algae. High coastal EPS levels suggest main pollution sources from livestock and shrimp farming. The threshold above which EPS impacts coral bleaching and density was estimated at 0.3-0.7 µg/g, providing insights for coral reef conservation.

Bromo-3-chloro-5,5-dimethylhydantoin (BCDMH), a widely used environmental disinfectant in aquaculture, may induce toxicity, adversely affecting the health and viability of aquatic organisms. Epigallocatechin-3-gallate (EGCG), a polyphenol present in green tea, exhibits antioxidant properties that can protect normal cells from oxidative stress. The findings suggest that exposure to BCDMH results in a reduction of antioxidant enzyme activity, whereas EGCG supplementation enhances crayfish immunity and alleviates damage. Moreover, BCDMH exposure is associated with a decrease in total hemocyte count and an increase in apoptosis rate; however, EGCG demonstrates a protective effect against BCDMH-induced cytotoxicity. Histopathological analysis indicates that exposure to BCDMH results in hepatopancreatic damage in crayfish, which is mitigated by EGCG. To identify the genes and pathways influenced by EGCG, a comparative transcriptome analysis was performed. Gene Ontology (GO) analysis revealed that proteolysis and innate immune response are significant biological processes induced by EGCG. Furthermore, KEGG pathway analysis identified endocytosis and phagosome as critical pathways modulated by EGCG. EGCG effectively enhanced the survival of crayfish challenged with V. alginolyticus following BCDMH exposure This study contributes to fully understand the mechanisms of EGCG in reducing the immunotoxicity of antibiotic residues on aquatic animals.

Angiotensin-I Converting Enzyme (ACE, EC 3.4.15.1) plays an essential role in controlling blood pressure. In this research, ACE inhibitors extracted from Arthrospira platensis thermolysin protease were provided using various chromatographic techniques, including reversed-phase high-performance liquid chromatography (RP-HPLC) and strong cation exchange chromatography (SCX). The amino acid sequence was determined by liquid-chromatography-tandem mass spectrometry (LC-MS/MS) and identified using two independent approaches: database-assisted identification and de novo sequencing. FY11 (FSESSAPEQHY) and IR5 (ILLYR) were established with the m/z 1281.54 and 677.37, respectively. The IC of IR5 from triplicate experiments was lower than FY11, with the value 10.54 ± 1.38 µM. IR5 was regarded as a non-competitive ACE inhibitor, with the docking interaction energy of - 106.842 kJ/mol. Docking results revealed that the interaction between ACE and peptide existed outside the ACE active site, excluding Arg 522, one of the Cl binding sites. Notably, the content of IR5 in 2 mg of crude thermolysin digest was determined to be 2.42 µg/mg using LC-MS/MS quantification. Based on all these features, Arthrospira peptides can be considered to be a potentially promising antihypertensive agent.

This review provides a general overview of collagen structure, biosynthesis, and biological properties, with a particular focus on marine collagen sources, especially fisheries discards and by-catches. Additionally, well-documented applications of collagen are presented, with special emphasis not only on its final use but also on the processes enabling sustainable and safe recovery from materials that would otherwise go to waste. Particular attention is given to the extraction process, highlighting key aspects essential for the industrialization of fish sidestreams, such as hygiene standards, adherence to good manufacturing practices, and ensuring minimal environmental impact. In this context, the EcoeFISHent projects have provided valuable insights, aiming to create replicable, systemic, and sustainable territorial clusters based on a multi-circular economy and industrial symbiosis. The main goal of this project is to increase the monetary income of certain categories, such as fishery and aquaculture activities, through the valorization of underutilized biomass.

Seaweed aquaculture is an expanding industry with innovative applications beyond the traditional uses as human foods and phycocolloids. Asparagopsis armata, a red seaweed, is cultivated as a feed supplement to reduce methane emission from ruminants. The manipulation of microbiota with seaweed beneficial microorganisms (SBMs) has shown promise in enhancing disease resistance and growth in seaweeds and has potential to aid the cultivation of A. armata. In this study, we developed a growth assay for the rapid selection of bacteria that promote the growth of A. armata tetrasporophytes. We tested bacterial strains from the genera Phaeobacter and Pseudoalteromonas for their impact on the growth of A. armata, as these bacteria have been recognized for their beneficial traits in other seaweeds. All strains significantly enhanced the specific growth rate (SGR) of A. armata tetrasporophytes compared to controls without bacterial treatment. Bacterial 16S rRNA gene amplicon sequencing confirmed the presence of the inoculated growth-promoting SBMs (SBM-Gs) in A. armata cultures with no significant impacts on the resident microbial community. Co-occurrence network analysis of the resulting communities demonstrated that the inoculated Phaeobacter spp. formed distinct modules, exclusively interacting with resident Phaeobacter species, while the Pseudoalteromonas sp. was absent from the network. These results demonstrate that microbial inoculation is an effective strategy for incorporating SBM-Gs into the A. armata microbiota to promote growth. The tested SBM-Gs may exert their influence by interacting with specific resident species or by directly affecting host physiology, resulting in minimal undesired effects on the microbiome.

Bacterial communities associated with living organisms play critical roles in maintaining health and ecological balance. While dominant bacteria have been widely studied, understanding the role of low-abundance bacteria has become increasingly important due to their unique roles, such as regulating bacterial community dynamics and supporting host-specific functions. However, detecting these bacteria remains challenging, as impurities in environmental samples mask signals and compromise the accuracy of analyses. This study explored the use of dielectrophoresis (DEP) as a practical approach to isolate low-abundance bacteria obscured by impurities, comparing its utility to conventional centrifugation methods. Using two shrimp species, Neocaridina denticulata and Penaeus japonicus, DEP effectively isolated bacterial fractions while reducing impurities, enabling the detection of bacteria undetected in centrifuged samples. These newly detected bacteria were potentially linked to diverse ecological and host-specific functions, such as nutrient cycling and immune modulation, highlighting DEP as a highly potential approach to support the study of host-microbial interactions. Overall, we believe that DEP offers a practical solution for detecting overlooked bacteria in conventional methods and exploring their diversity and functional roles, with potential contributions to aquaculture and environmental biotechnology.

Monocrotophos (MCP), an organophosphate insecticide commonly used in agriculture, has raised concerns due to its runoff into aquatic ecosystems and causes potential adverse effects on fish. The present study envisaged the understanding of the impact of MCP on the ovarian tissues of Anabas testudineus (climbing perch), an air-breathing food fish often found close to agricultural fields, making it a valuable bio-indicator of agrochemical contamination. Transcriptome profiling of ovarian tissues in response to 45 days of MCP exposure at sub-lethal concentrations was performed. Using Illumina platform sequencing, a total of 144.51 million reads were produced. After filtering and trimming, 138.82 million high-quality reads were obtained, of which 96.10% were mapped to the Anabas genome. Expression analysis revealed a total of 54 significant differentially expressed genes (DEGs), including 28 upregulated genes, and 26 downregulated genes compared to the control group (Log2 FC >  ± 1 and, adjusted p-value < 0.05). Gene ontology analysis of the DEGs revealed associations with molecular, biological, and cellular functions. Key detoxification genes, such as glutathione S-transferase and UDP-glucuronosyltransferase, were significantly upregulated, indicating an enhanced detoxification response to MCP. In contrast, cytochrome P450 family 1 subfamily A (cyp1a1), a gene critical for steroid hormone metabolism, was downregulated, suggesting disruptions in hormone regulation. Functional enrichment analysis highlighted several affected processes, including steroid hormone biosynthesis, oocyte meiosis, apoptosis, and progesterone-mediated oocyte maturation. The randomly selected eight DEGs using RT-qPCR confirmed consistent gene expression levels in line with the transcriptome data. This work identified significant genes associated with detoxification and reproduction events in the ovarian tissues for maintaining homeostasis. This will also serve as valuable information for further investigation of the association of the identified genes with the reproductive biology of fish in response to toxicants or pollutants.

The razor clam (Sinonovacula constricta) is a key species in marine aquaculture, known for its wide salinity adaptation, and potential for cultivation in saline-alkaline water. Understanding its response mechanisms is crucial for expanding its farming into these regions. This study reveals the response mechanisms of S. constricta in response to low-salinity alkaline stress through a combined analysis of transcriptomics and metabolomics. After 24 h of salt-alkali stress (SA group), 1378 differentially expressed genes (DEGs) were identified, with enriched pathways including glycerophospholipid metabolism, serine, taurine, and hypotaurine metabolism. Additionally, 341 significantly different metabolites (SDMs) were found, primarily involved in taurine and hypotaurine metabolism, purine metabolism, and the FoxO signaling pathway, etc. Both DEGs and SDMs were notably enriched in hypotaurine metabolism, glycerophospholipid metabolism, and the mTOR signaling pathway, showing significant upregulation in the SA group. Correlation analysis found that the integrated regulatory network was involved in the synthesis of taurine, glycerophospholipids, and L-glutamic acid, and the metabolism of 3-mercaptopropionic acid. These results suggest that low salinity and alkalinity induce stress responses in S. constricta by regulating osmotic balance, phospholipid synthesis, and lipid metabolism. This study offers insights into the molecular mechanisms of salt-alkali response in S. constricta.

Acetyl-coenzyme A carboxylases (ACCs) catalyze the initial reaction of fatty acid (FA) biosynthesis. The marine diatom Phaeodactylum tricornutum has two nuclear-encoded ACCs (PtACC1 (Phatr3_EG01955) and PtACC2 (Phatr3_J55209)), both which are homomeric and predicted to be localized in the plastids and the cytosol, respectively. In this study, we focused on stromal ACC1 by constructing P. tricornutum strains expressing GFP-tagged PtACC1 (ACCG strains) and confirmed that PtACC1 was localized in or around the pyrenoid. Here, we showed that unsaturated FAs (UFAs) composing the thylakoid membrane lipids increased in PtACC1 strains grown under high light conditions (190 µmol photons m s), and that the content of triacylglycerol (TAG) and unsaturation ratios in TAG increased under oxidative stresses (with added 50 µM HO). ACCG strains showed faster growth rates than wild type under high light and/or oxidative stress conditions. These results suggest that cell proliferation is maintained by an accelerated recovery of PSII due to the increased UFAs in the thylakoid membrane in ACCG strains grown in high light, and that increased UFAs in ACCG cells enhanced the tolerance to oxidative stresses presumably due to the increased scavenging capacity of UFAs against reactive oxygen species. The introduction of plastidic ACC resulted in stimulating supply of UFAs to specific lipids that in turn enhanced tolerance to various stresses.

High temperature restricts the survival and growth of aquatic organisms. Probiotics have significant potential for mitigating the negative effects of temperature stress on fish. In this study, the American shad (Alosa sapidissima), a temperature-sensitive freshwater fish, was selected as the experimental paradigm to dissect the underlying mechanisms governing the interactions between the host and its microbiome, with a particular focus on the impact exerted by the probiotic Lactococcus lactis within a high-temperature setting. We evaluated the effects of probiotics on the growth and biochemistry of A. sapidissima by measuring relevant parameters and enzyme activities and conducted an integrated microbiome-transcriptome analysis to assess the impacts on the gut microbiota and uncover probiotic-regulated metabolic pathways. The findings of our research indicated that probiotics had beneficial effects on growth; the activities of enzymes such as LPS, T-SOD, and GSH-PX; and the gut microbial composition. Furthermore, the configuration of the intestinal microbiota underwent a transformation, as evidenced by the increased relative prevalence of bacteria with potential beneficial properties, including Bacillus, Lactococcus, and Clostridium. Liver transcriptomic analysis revealed 586 differentially expressed genes (DEGs). The expression of immune-related genes (nfil3-2, il17d, and leap2) and lipid metabolism-related genes (pla2g3 and sc5d) was strongly upregulated. KEGG enrichment analysis revealed that the DEGs were predominantly clustered within metabolic pathways such as circadian rhythm and fatty acid degradation. This study revealed that probiotics enhanced intestinal bacterial diversity and eased stress by regulating the circadian rhythm, immunity, and lipid metabolism under high-temperature conditions. This study provides a reference for the use of probiotics in A. sapidissima at high temperatures.

This article aims to reveal the optimal peptide segment with antioxidant activity from Dalian Stichopus japonicus, investigate its anti-melanogenesis effect, and elucidate its mechanisms of action both in vitro and in vivo. The best antioxidant alcalase hydrolysates, identified by the previous screening of proteases, was isolated by ultrafiltration; it was found that the components with a molecular weight of ≤ 3 kDa exhibited the best activity. The chemical components were characterized using LC-MS/MS. Through molecular docking, GPIGF was identified as the peptide segment with the best antioxidant and melanogenesis-inhibitory activity. A search in the NCBI database revealed that GPIGF is a newly obtained natural oligopeptide. Further experiments with synthesized GPIGF in vitro showed that it effectively reduces cell apoptosis and damage, and inhibits the expression of melanin-related genes, including tyrosinase (TYR), and associated proteins TRP-1, TRP-2, and MITF. In vivo experiments with the zebrafish model demonstrated that GPIGF significantly inhibits AAPH-induced apoptosis in zebrafish larvae, reduces the production of ROS, and suppresses melanin generation on the skin surface without exhibiting embryotoxicity. This study provides a research foundation for the development of antioxidants from Dalian Stichopus japonicus, which could serve as natural whitening and anti-aging agents, supporting its integrated utilization and development.

Hepcidin is a cysteine-rich antimicrobial peptide that plays an important role in fish immunity. In the current study, we report a novel isoform of hepcidin (Jd-Hep) from Sin croaker, Johnius dussumieri, with an open reading frame (ORF) of 258 nucleotide bases that encodes 85 amino acids containing a signal peptide (24 amino acids), a prodomain (35 amino acids) and a biologically active mature peptide (26 amino acids). Phylogenetic tree analysis showed that J. dussumieri hepcidin belonged to the HAMP2 cluster of hepcidin. The tissue distribution showed that the expression of hepcidin was highest in the liver in wild-caught J. dussumieri. The mature peptide mJd-Hep was recombinantly expressed in a prokaryotic host, E. coli Rosetta-gami™B (DE3) pLysS cells, and the peptide was isolated and purified. The recombinant peptide, rJd-Hep, exhibited notable antibacterial activity against aquatic pathogens such as Aeromonas hydrophila, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio proteolyticus, and Vibrio fluvialis. The mode of action of the peptide was proven to be membrane-based (pore formation and depolarization). The rJd-Hep was found to be non-hemolytic to hRBCs and non-cytotoxic to the mammalian cell line. The peptide showed 85% growth inhibition of cancer cell line, MCF-7. These findings expand our knowledge of the potential application of hepcidin in aquaculture as a therapeutic agent.

Streptococcal disease results in major mortality events of both marine and freshwater fishes worldwide. Streptococcus iniae is among the prominent causative bacterial strains as it has been found to cause a higher incidence of mortality and act as a zoonotic pathogen. Here, we examine the susceptibility of two important aquaculture species in the USA, striped bass (Morone saxatilis) and white bass (Morone chrysops) to S. iniae. A high incidence of mortality was observed in both species, although striped bass succumbed more rapidly than white bass. Spleen gene expression at three time points following infection was analyzed to further elucidate the mechanisms underlying these observations. The down-regulation of gene transcripts associated with pathogen detection (tlr1, tlr8, tlr9), antigen processing (cd74a), immune cell recruitment and migration (ccr6b, ccr7), macrophage function (csf1ra), T-cell signaling, and NF-kB activation (card11, fyna, tirap) was detected in both species. These findings potentially indicate impairment in these critical early immune system processes such that both species were ultimately highly susceptible to S. iniae infection despite the detected up-regulation of transcripts typically associated with effective immune response, such as cytokines (il1β, il8, il12b2, il17rc, tnfα) and hepcidins (hamp, hamp2). The presented results collectively identify several candidate genes and associated pathways for further investigation to characterize the vulnerability of striped bass and white bass to S. iniae and that may be considered for selective breeding efforts, biotechnological intervention, and/or exploitation in the development of vaccines and alternative treatments.

Coastal hypoxia is an increasing environmental concern affecting marine ecosystems globally, particularly impacting benthic organisms such as bivalves. Although previous studies focused on the physiological responses of bivalves to hypoxic stress, the role of resident bacteria in the host response to hypoxia remains poorly understood. This study investigated changes in the resident bacterial communities in the gills and hepatopancreatic tissues of the ark shell (Anadara kagoshimensis) under hypoxic conditions. Specimens were assigned to three treatment groups: untreated control, hypoxia, and hypoxia with chloramphenicol supplementation (5.0 mg/L). After 3 days, specimens exposed to hypoxia exhibited black precipitation in the culture water, whereas antibiotic treatment reduced these effects. Amplicon sequencing revealed distinct bacterial communities between the tissues, with Arcobacteraceae and Alkalispirochaetaceae dominating in the gills and Metamycoplasmataceae being predominant in the hepatopancreas. The hepatopancreas displayed greater bacterial community changes than the gills under hypoxic conditions, including an increase in the abundance of Metamycoplasmataceae. The predicted metabolic functions suggested that these bacteria contribute to iron sulfide precipitation through sulfate reduction and iron respiration. The antibiotic-treated group displayed bacterial communities more similar to those of the control group, confirming the effectiveness of chloramphenicol in suppressing bacterial changes under hypoxia. This study provided new insights into tissue-specific bacterial responses to hypoxia in A. kagoshimensis and highlighted the potential role of Metamycoplasmataceae in the bivalve's response to hypoxic stress.

Flow velocity is a critical environmental factor influencing the growth, energy metabolism, and physiological health of aquaculture species. This study investigated the physiological and molecular responses of spotted sea bass (Lateolabrax maculatus) under experimental conditions simulating flow velocities typical of land-based recirculating aquaculture systems (RAS) and deep-sea cage systems. High flow velocities (HFV, 0.35-0.65 body lengths per second [BL/s]) enhanced growth performance compared to low flow velocity (LFV, 2.28-2.85 BL/s) conditions. Histological analysis revealed reduced hepatic lipid accumulation under HFV, while LFV promoted lipid storage. Serum analyses showed elevated antioxidant enzyme activity in the LFV group but higher oxidative stress markers in the HFV group. Transcriptomic profiling identified foxo3 as a key regulatory hub orchestrating metabolic and oxidative stress adaptations. Genes associated with oxidative damage repair, lipid catabolism, and glucose metabolism were significantly enriched under hydrodynamic stress. Enrichment of the FoxO signaling pathway highlighted its central role in mediating oxidative stress mitigation and energy mobilization. These findings demonstrate the dual effects of flow velocity, where higher velocities promote growth and metabolic activity at the cost of oxidative stress, and lower velocities conserve energy while maintaining oxidative stability. Tailored flow velocity conditions can optimize fish welfare and productivity across aquaculture systems. Future studies should investigate the systemic effects of hydrodynamic stress using multi-omics approaches to advance sustainable aquaculture practices.

The ploidy detection is crucial for the oyster industry. The objective of this study was to develop a method that verifies ploidy of the triploid Pacific oyster Crassostrea gigas by analyzing the diversity of triploid through microsatellite multiplex PCRs using fluorescent universal primers. We developed four information-rich multiplex PCR panels, comprising a total of 12 genomic microsatellites located in the genome of the C. gigas, distributed across seven chromosomes with an average of 14 alleles per locus. Each panel used M13(-21) primers labeled with specific fluorochrome dyes, and the forward primers for each locus were appended with M13(-21) sequences. We validated the approach to infer ploidy using flow cytometry as a reference, finding > 95% agreement between these methods, and demonstrated its potential utility to infer aneuploidy. Genotyping of 496 triploid samples from eight populations yielded 10 or more alleles per locus in 99.63% of samples in a single capillary electrophoresis. The correct assignment of triploidy depends on the number of markers with three unique allele fragments (MNM). Using semi-strict criteria of three unique alleles at one or more loci, the detection accuracy rate was 95.26% for triploids. Using the strict criteria of three unique alleles at two or more loci, the detection accuracy rate was 98.34%. Populations with reduced genetic diversity due to selective breeding were better suited for the semistrict criterion, maximizing triploid detection. And cultured populations were more suitable for evaluation using the strict criteria, which effectively reduced false-positive diploid assignment and increased triploid detection accuracy. The markers developed in this study were highly polymorphic and effective for assessing genetic diversity and distinguishing populations, providing a reliable tool for triploid detection and analysis in oyster breeding.

T-box transcription factor 2 (TBX2) plays a critical role in various biological processes, including cell cycle regulation, malignant transformation, and regulating melanogenesis. In our previous study, we identified a Crassostrea gigas TBX2 (CgTBX2) and investigated its regulatory role in melanin production in oysters. Here, the mechanism of CgTBX2 in regulating cell proliferation was investigated. First, we found that CgTBX2 promoted the proliferation of mouse melanoma (B16F10) cells. CgMITF-X3, a 1347 bp transcript isoform of MITF from C. gigas, was then cloned and it was also found to promote cell proliferation. Co-transfection of CgTBX2 and CgMITF-X3 into B16F10 cells had a synergistic effect on cell proliferation, suggesting that CgMITF-X3 enhanced the function of CgTBX2 in promoting cell proliferation. CgMITF-X3 promoted the transcriptional activation of CgTBX2 by directly binding to the TCTCACGCGG sequence in the CgTBX2 promoter region. In addition, CgTBX2 and CgMITF-X3 proteins were co-located in the nucleus, indicating that these two proteins may perform a certain function collectively in the nucleus. Taken together, our findings revealed that CgTBX2 is directly activated by CgMITF-X3 at the transcriptional level, and both CgTBX2 and CgMITF-X3 facilitate cell proliferation.

The increasing plastic production causes serious problems in the marine environment, and the main source of plastic waste comes from the fishing and aquaculture industries. Although there have been various efforts to develop aquaculture equipment with marine biodegradable plastics, an urgent need is to develop an assay to evaluate their biodegradation in aquaculture environments. This study focused on evaluating the biodegradation of biomass plastic in recirculating aquaculture systems (RAS) that mimic freshwater, brackish water, and saltwater aquacultures. The methods used to assess biomass plastic biodegradability included changes in physical properties, weight loss, biochemical oxygen demand, and microbial community investigation using poly(butylene succinate-co-adipate) (PBSA) as a model. Scanning electron microscopy studies indicated the erosion on the biomass plastic surface from 1 to 2 days in the RAS tank (salinity, 0-0.5%) harboring Nile tilapia (Oreochromis niloticus). 4',6-Diamidino-2-phenylindole fluorescence microscopy confirmed the presence of the microorganisms on the PBSA surface. The microorganisms in RAS tanks degraded 11.6% of 1 g/L PBSA in 7 days, demonstrating their biodegradation potential. 16S rRNA gene sequencing showed that Pseudomonas plays a major role as an early decomposer in the biodegradation process within 24 h. A multifaceted analytical method that provides sufficient evidence was developed to show that the erosion on the PBSA surface in RAS tanks results from biodegradation. The ability of RAS to control various aquatic environments (pH, salinity, temperature, and bacterial density) makes it suitable for testing the marine biodegradability of biomass plastics for use in aquaculture and fishery industries.