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Microcystins (MCs) are prevalent harmful contaminants within shrimp aquaculture systems, exhibiting a diverse array of variants. Gut microbiota can engage in mutual interactions with the host through the gut-liver axis. In this study, the shrimp Litopenaeus vannamei were subjected to three different variants of MCs (LR, YR, RR) at a concentration of 1 μg/L each, and elucidated the alterations in both intestinal microbiota and hepatopancreas physiological homeostasis. The results showed that all three variants of MCs prompted histological alterations in the hepatopancreas, induced elevated levels of oxidative stress biomarkers (H 2 O 2 , T-SOD, and CAT), disturbed the transcription levels of immune-related genes (Crus , ALF , and Lys), along with an increase in apoptotic genes (Casp-3 and P53). Furthermore, the metabolic profiles of the hepatopancreas were perturbed, particularly in amino acid metabolism such as "lysine degradation" and " β -alanine metabolism"; the mTOR and FoxO signaling were also influenced, encompassing alterations in the transcription levels of related genes. Additionally, the alterations were observed in the intestinal microbiota's diversity and composition, particularly potential beneficial bacteria (Alloprevotella , Bacteroides , Collinsella , Faecalibacterium , and Prevotellaceae UCG-001), which exhibited a positive correlation with the metabolite berberine. These findings reveal that the three MCs variants can impact the health of the shrimp by interfering with the homeostasis of intestinal microbial and hepatopancreas physiology. [Display omitted] • The homeostasis of oxidative stress, antimicrobial and apoptosis were affected in the hepatopancreas. • Lysine degradation and β -alanine metabolism were disturbed in the hepatopancreas. • The metabolism and gene transcription related to mTOR and FoxO signaling have been influenced. • Intestinal microbial diversity, community composition, and metabolic function were disturbed. • Several intestinal bacteria exhibited a positive correlation with the metabolite berberine of the host. [ABSTRACT FROM AUTHOR]

• Effects of three variants of microcystins on the intestinal physiological of the shrimp was analyzed. • Intestinal histological morphology and physiological homeostasis was disturbed. • MC-LR stress induced more differential metabolites than that of MC-YR and MC-RR. • Purine metabolism function was affected by the stress of three MCs variants. • The strategies of intestinal amino acid metabolism to the stress of three MCs variants were different. Microcystins (MCs) are harmful substances to the health of cultured shrimp, and there are many variants of MCs. Intestinal is the immune and metabolic center of the shrimp, and is also the target organ for MCs toxicity. In this study, the shrimp Litopenaeus vannamei juvenile were separately exposed to 1 μg/L of three MCs variants (LR, YR, RR) for 72 h respectively, and the changes of intestinal morphology, physiological response and metabolic function were analyzed. The results showed the three MCs variants stress caused intestinal mucosal damage and disordered the homeostasis of antimicrobial genes (ALF and Lys) expression. The mRNA expression levels of antioxidant genes (Nrf2 and GPx) and apoptosis factors (CytC and Casp-3) were increased, but that of detoxification gene (CYP450) was decreased. Furthermore, the intestinal metabolic pattern was also influenced by stresses, among which MC-LR induced more differential metabolites than that of MC-YR and MC-RR. The function of purine metabolism was highly influenced by the stress of three MCs variants, followed by amino acid metabolism, but there were differences in the types of amino acids. The metabolites citric acid, L-glutamine, L-tryptophan, spermine, UMP, and indole contributed to the metabolic pathway network. Nineteen stress-related metabolites were identified as candidates for subsequent screening of potential biomarkers. These results revealed the toxic effects of three MCs variants on the intestinal physiological and metabolic homeostasis of the shrimp. [ABSTRACT FROM AUTHOR]

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a member of the Cap'n′collar basic region leucine zipper (CNC-bZIP) transcription factor family, and is activated by diverse oxidants, pro-oxidants, antioxidants and chemopreventive agents. The full-length cDNA of Nrf2 from Penaeus monodon (PmNrf2 ; 2024 bp long with 729 bp coding region, GenBank accession no. MW390830) was cloned. The 242-amino-acid polypeptide encoded by this gene had a predicted molecular mass of 27.80 kDa. Sequence homology and phylogenetic analysis showed that PmNrf2 was similar to the insect Cap'n′Collar (CNC) transcription factor and mammalian Nrf2. Tissue expression profile analyzed by quantitative real-time RT-PCR (qRT-PCR) demonstrated that PmNrf2 was constitutively expressed in all examined tissues, with the highest expression observed in the intestines and the weakest expression observed in the hemocyte. PmNrf2 expression profiles were detected in the hepatopancreas of shrimp after bacterial challenge. The results suggested that PmNrf2 was involved in the responses to bacterial challenge, but the temporal expression pattern trend of PmNrf2 differed between the gram-negative and gram-positive bacterial challenges in the shrimp hepatopancreas. The recombinant PmNrf2 protein was expressed and purified through affinity chromatography. Furthermore, an anti-PmNrf2 polyclonal antibody was obtained, which was able to clearly detect PmNrf2 protein expression in the hepatopancreas of shrimp. Knockdown of PmNrf2 by RNA interference (RNAi) resulted in a reduction in the expression of PmGPx gene. Taken together, the results of our study indicated that PmNrf2 played a role in regulation the transcription of PmGPx antioxidant enzyme genes. • The full-length cDNA of Nuclear factor erythroid 2-related factor 2 (Nrf2) was obtained from Penaeus monodon (PmNrf2). • PmNrf2 expressed in all examined tissues with the strongest expression in intestines. • PmNrf2 involved in the responses to bacterial challenge. • PmNrf2 probably regulates the expression of PmGPx via the Nrf2 signaling pathway. [ABSTRACT FROM AUTHOR]

Penaeus monodon provides a high‐quality protein source for humanity, and pond cultured shrimp often presents asynchronous growth. Microbial communities are important for the digestion and immunity of shrimp. Therefore, in this study, we investigated the bacterial characteristics of the intestine and rearing water of asynchronously growing P. monodon that were cultured in outdoor and indoor pond respectively. The results showed that the bacterial community of the rearing water was more complex than that of the intestine; the fast‐growing shrimp in the indoor pond had higher intestinal bacterial diversity. Besides, the dominant bacterial composition of the water was more complex than that of the intestinal. Specifically, the abundance of Proteobacteria in the intestine was consistent with the growth performance of shrimp in the outdoor pond, which was exactly the opposite in the indoor pond. At the genus level, two cyanobacteria, Limnothrix and Cyanobium PCC‐6307, were dominant in the indoor and outdoor water respectively. In the outdoor pond, Bacillus was dominant in the slow‐growing shrimp intestines, while Vibrio was dominant in the fast‐growing shrimp. The intestinal microbes of the fast‐growing shrimp had higher proteasome metabolic capacity. These results can provide new insights into microbiome characteristics involved in the asynchronous growth of shrimp. [ABSTRACT FROM AUTHOR]

The intestine is important for nutrition, metabolism and immunity. Succinate (SA) plays a vital role in the physiological homeostasis of animal intestines. However, the effects of dietary SA on the intestinal immunity and metabolism in shrimp are not clear. In this study, we investigated the immune and metabolic responses in the intestine of Litopenaeus vannamei that were fed diets consisting of different levels of SA: 0 g/kg (Con) and 10 g/kg (SA) for 56 days. The results from a RNA-seq analysis identified 6005 differentially expressed genes (DEGs), including 2728 upregulated genes and 3277 downregulated genes, which were grouped into 312 pathways. The DEGs were most enriched in pathways related to protein synthesis and amino acid metabolism, including "ribosome", "aminoacyl-tRNA biosynthesis", "pyrimidine metabolism", and "arginine and proline metabolism"; additionally, carbohydrate and lipid metabolism pathways were also activated. A large number of immune-related genes were associated with mucus barrier modification, antimicrobial activity, pathogen attachment and recognition, antioxidant activity, and apoptosis. The expression patterns of several candidate genes involved in the immune response and nutrition metabolism were detected by qPCR. This study provides insight into the transcriptomic modulating mechanisms associated with intestinal immunity and the metabolism of L. vannamei in response to the intake of dietary SA. • Intestine transcriptomic of Litopenaeus vannamei fed with succinate was analyzed. • 2728 up-regulated and 3277 down-regulated genes were identified. • The most enriched pathway was involved in protein synthesis and amino acid metabolism. • Succinate induced intestine immune and metabolism responses. • Immune genes in response to succinate were identified. [ABSTRACT FROM AUTHOR]

Simple Summary: Ammonia is a major water quality factor influencing the survival and health of shrimp, among which the gill is the main effector organ for ammonia toxicity. In this study, we explored the toxicity of ammonia stress on the physiological homeostasis in the gills of Litopenaeus vannamei under seawater and low-salinity conditions. This study included four groups, namely the SC group (ammonia-N 0 mg/L, salinity 30‰), SAN group (ammonia-N 10 mg/L, salinity 30‰), LC group (ammonia-N 0 mg/L, salinity 3‰), and LAN group (ammonia-N 10 mg/L, salinity 3‰). The ammonia stress lasted for 14 days. The results show that ammonia stress caused the severe contraction of gill filaments and the deformation or even rupture of gill vessels. Ammonia stress could also influence the redox, ER function, apoptosis, detoxification, energy metabolism, and osmoregulation of the shrimp gills. These results are helpful to analyze the toxicological mechanism of ammonia stress on the seawater- and low salinity-cultured shrimp. Ammonia is a major water quality factor influencing the survival and health of shrimp, among which the gill is the main effector organ for ammonia toxicity. In this study, we chose two types of Litopenaeus vannamei that were cultured in 30‰ seawater and domesticated in 3‰ low salinity, respectively, and then separately subjected to ammonia stress for 14 days under seawater and low-salinity conditions, of which the 3‰ low salinity-cultured shrimp were domesticated from the shrimp cultured in 30‰ seawater after 27 days of gradual salinity desalination. In detail, this study included four groups, namely the SC group (ammonia-N 0 mg/L, salinity 30‰), SAN group (ammonia-N 10 mg/L, salinity 30‰), LC group (ammonia-N 0 mg/L, salinity 3‰), and LAN group (ammonia-N 10 mg/L, salinity 3‰). The ammonia stress lasted for 14 days, and then the changes in the morphological structure and physiological function of the gills were explored. The results show that ammonia stress caused the severe contraction of gill filaments and the deformation or even rupture of gill vessels. Biochemical indicators of oxidative stress, including LPO and MDA contents, as well as T-AOC and GST activities, were increased in the SAN and LAN groups, while the activities of CAT and POD and the mRNA expression levels of antioxidant-related genes (nrf2, cat, gpx, hsp70, and trx) were decreased. In addition, the mRNA expression levels of the genes involved in ER stress (ire1 and xbp1), apoptosis (casp-3, casp-9, and jnk), detoxification (gst, ugt, and sult), glucose metabolism (pdh, hk, pk, and ldh), and the tricarboxylic acid cycle (mdh, cs, idh, and odh) were decreased in the SAN and LAN groups; the levels of electron-transport chain-related genes (ndh, cco, and coi), and the bip and sdh genes were decreased in the SAN group but increased in the LAN group; and the level of the ATPase gene was decreased but the cytc gene was increased in the SAN and LAN groups. The mRNA expression levels of osmotic regulation-related genes (nka-β, ca, aqp and clc) were decreased in the SAN group, while the level of the ca gene was increased in the LAN group; the nka-α gene was decreased in both two groups. The results demonstrate that ammonia stress could influence the physiological homeostasis of the shrimp gills, possibly by damaging the tissue morphology, and affecting the redox, ER function, apoptosis, detoxification, energy metabolism, and osmoregulation. [ABSTRACT FROM AUTHOR]

To solve the nitrate accumulation phenomenon in recirculating aquaculture system (RAS). This study aimed to provide a sufficient organic carbon source, denitrifying bacteria, and a suitable microenvironment for denitrification in RAS. Denitrifying capsules were prepared using the encapsulation method, the morphology, microbial community and influencing factors for nitrogen removal efficiency of the denitrifying capsules in synthetic RAS wastewater were investigated. The denitrifying capsules had a porous, rough, and loose structure, with a diameter of approximately 6 mm and a density of approximately 1.05 g per cubic centimeter. The effect of a low ratio of solid-to-liquid (10:1) and temperature (15 °C) on nitrate removal was significant during the initial acclimation period (1-10d). After the enclosed denitrifying bacteria activity was recovered, the influence was not significant. At the end of the test, the nitrate removal rate could reach more than 80% even at a lower ratio of solid-to-liquid (10:1) or at 15 °C. The capsule exhibited a short adaptation time for diverse types of substrates and adapted well to the substrate concentration. Under low influent nitrate or nitrite loading, the removal rate reached 80% on the 6th day, which was earlier than with high influent nitrate loading. The denitrification rate experiment showed that the nitrate removal rate could reach 80.14% at 14 h and finally stabilize at approximately 81.89%. The capsule-supported denitrification process was a zero-order reaction and the denitrification rate of the capsule was calculated to be 109.0 mg N/L-capsule·h. The longtime evaluation indicated that until the semen litchi powder was exhausted, the capsule could retain a high nitrate removal rate. Functional enzyme analysis reveals the nitrogen conversion pathway in the capsule included denitrification, dissimilatory nitrate reduction and nitrogenfixation. The porous structure and good adaptability to environmental conditions of the denitrifying capsule would help to achieve denitrification and reduce the nitrate content on the present RAS, without increasing infrastructure investment. • Core-shell structure denitrifying capsule was designed for denitrification in RAS. • The capsule adapted well to substrate concentrations and temperature. • Afther a short activation time the nitrate removal rate could reach 96.6%. • Denitrification prosess in RAS may achieve easily with the denitrifying capsule. [ABSTRACT FROM AUTHOR]

Abstract pH of water environment affects the survival of aquatic animals. Intestine barrier function influences the health of animals, which is related to its mucosa structure, immune components, and microbial communities. In this study, we investigated the histological structure, digestive and metabolic capacity, immune responses, and microbial composition in the intestine of Litopenaeus vanmei under three different conditions: control (pH 8.3), low pH stress (pH 6.9), and high pH stress (pH 9.7) for 72 h. The results showed both low and high pH stress disrupted the intestine morphological structure, and induced variations in the activities of digestive (AMS, LPS, Tryp, and Pep) and metabolic (HK, PK, CCO, and LDH) enzymes. Low and high pH stress also increased oxidative stress (MDA, LPO, PC, and ·O 2 − generation), and decreased the antioxidant enzyme activities (T-AOC, SOD, and GST); shrimp enhanced CAT activity and HSP70 , Trx , MT and Fer gene transcripts as defense mechanism. Additionally, Immune confusion was also found in the shrimp intestine in response to low and high pH stress, including the antibacterial ability (T-NOS, PO, proPO , ALF , and Lys), pathogen recognition (TLR and Lec), apoptosis (Casp , IAP and p53), and mucus homeostasis (Muc-1 , Muc-2 , Muc- 5AC, Muc-5B , and Muc-19). pH exposure also decreased the diversity of the intestine bacterial, disturbed the composition of microbiota, and decreased the microbial metabolite SCFA contents. Our results indicated that acute pH stress can impair the intestine barrier function of white shrimp, probably via destroying mucosa structure, confusing digestion and metabolism, inducing oxidative stress, disordering immunity, and disrupting the microbial composition. Highlights • Intestine barrier function of Litopenaeus vannamei subjected to low pH and high pH stress was investigated. • Low and high pH stress disordered the intestine morphological structure, energy and respiratory metabolic homeostasis. • Low and high pH stress induced the intestine oxidative stress and confused antioxidant function. • Low and high pH stress confused the intestine immune function. • Low and high pH stress changed the intestine microbiota composition and SCFA contents. [ABSTRACT FROM AUTHOR]

Abstract Harmful effects of water pollutants are myriad. Sulfide from water bodies affects the aquatic animals. Intestine barrier function serves as the front-line of animals defense. Our previous study confirmed the toxic effect of sulfide on intestine immune response of Litopenaeus vannamei , but the underlying mechanisms remained elusive. Therefore, in this study, we investigated the transcriptomic and microbiota responses of the L. vannamei intestine subjected to acute sulfide exposure. Sulfide decreased bacterial richness and altered the intestine microbiota composition. Specifically, sulfide increased the abundances of Bacteroidetes and Actinobacteria, but decreased the abundance of Proteobacteria. At the genus level, sulfide increased typical cellulolytic characteristics bacteria, such as Formosa , Sphingomonas , and Demequina. RNA-seq analysis identified differential expression of 1799 genes (701 up-regulated and 1098 down-regulated) were grouped into 267 pathways. The most enriched pathway 'amoebiasis' was related to the intestine mucus homeostasis. A number of immune-related genes associated with antimicrobial, antioxidant, pathogen attachment and recognition, and apoptosis processes in contrasting accessions; they were correlated with the abundance of intestine bacterial at the phylum level. This study provides an insight into the mechanisms associated with molecular and microbiota response and processes involved in adaptation strategies towards sulfide stress. Highlights • Transcriptomic and microbiome responses of the Litopenaeus vannamei intestine exposed to sulfide stress was studied. • Sulfide decreased bacterial richness and altered the intestine microbiota composition. • 701 up-regulated and 1098 down-regulated genes differentially expressed in response to sulfide exposure. • The most enriched pathway "amoebiasis" was related to the intestine mucus homeostasis. • We speculated a potential mechanism of intestine barrier function in the contrasting accessions towards sulfide exposure. [ABSTRACT FROM AUTHOR]

Sulfide is a harmful environmental pollutant that affects the survival and immunity of shrimps. The gill is important for shrimp respiratory and osmotic adjustment, the physiological and immune homeostasis of the organ can be influenced by sulfide. In this study, we investigated the acute toxicity of sulfide (5 mg/L) on the morphology, physiological and immune response in the gills of Litopenaeus vannamei . H&E stain showed that sulfide stress damaged the gills histological structure. Specifically, osmoregulation capacity including of Na + /K + -ATPase and Ca 2+ /Mg 2+ -ATPase activity was both increased at 6 h and 12 h, and decreased at 72 h; the contents of free amino acid including of Gly, Pro, Ser, Thr and Ala were decreased at 72 h. Respiratory metabolic enzymes, such as cytochrome c oxidase and succcinate dehydrogenase activity was decreased at 12 h-72 h, while fumarate reductase and lactate dehydrogenase activity kept a higher level at 12 h-72 h. Significant variations in the activities of immune enzymes (acid phosphatase, alkaline phosphatase, total antioxidant capacity and lysozyme). The expression of immune-related genes (heat shock protein 70, thioredoxin and caspase-3) was increased at first and then decreased, while hypoxia inducible factor 1α kept a higher level at 6 h-72 h. These results revealed that sulfide stress influenced the L. vannamei gills physiological and immune function by damaging histological structure, and confusing osmoregulation, respiratory metabolic and immune capacity. [ABSTRACT FROM AUTHOR]

• The shrimp survival and growth were reduced and the hepatopancreas histological was damaged. • The major molecular pathways in the hepatopancreas in response to CA stress were investigated. • The genes of PRRs, phenoloxidase system and detoxification metabolism were affected. • The genes of substance transport-related regulators and transporters were mostly downregulated. • The remodeling patterns for the variations of major amino acid metabolic were derived. Carbonate alkalinity (CA) is one of the environmental factors affecting the survival and growth of aquatic animals. However, the toxic effects of CA stress on Pacific white shrimp Litopenaeus vannamei at the molecular level are completely unclear. In this study, we investigated the changes of the survival and growth, and hepatopancreas histology of L. vannamei under different levels of CA stress, and integrated transcriptomics and metabolomics to explore major functional changes in the hepatopancreas and identify biomarkers. After CA exposure for 14 days, the survival and growth of the shrimp were reduced, and the hepatopancreas showed obvious histological damage. A total of 253 genes were differentially expressed in the three CA stress groups, and immune-related genes such as pattern recognition receptors, phenoloxidase system and detoxification metabolism were affected; substance transport-related regulators and transporters were mostly downregulated. Furthermore, the metabolic pattern of the shrimp was also altered by CA stress, especially amino acids, arachidonic acid and B-vitamin metabolites. The integration analysis of differential metabolites and genes further showed that the functions of ABC transporters, protein digestion and absorption, and amino acid biosynthesis and metabolism were highly altered by CA stress. The results of this study revealed that CA stress caused immune, substance transport, and amino acid metabolic variations in L. vannamei , and identified several potential biomarkers related to stress response. [ABSTRACT FROM AUTHOR]

Abstract Intestine barrier serves as the front-line of shrimp defense, which rely on its structural integrity, microbial composition, and mucus immune compounds. Mucins are the major organic components of the intestine mucus layer that contribute to the immunity of intestine mucus. In this study, we examined the histological structure, microbial composition, and mucin genes expression in the intestines of Litopenaeus vanmei under three different conditions: control, ammonia stress, and nitrite stress for 72 h. H&E stain showed that ammonia and nitrite stress exposure both damaged the intestine mucosal tissue. High-throughput 16S rDNA sequencing revealed that two stresses exposure decreased the bacterial diversity, and altered the composition of intestine microbial. Specifically, the dominant bacterial phyla Bacteroidetes abundance was increased, while Proteobacteria and Planctomycetes were decreased; at the genus level, Formosa abundance was increased and Photobacterium was decreased, opportunistic pathogens including Nautella and Pseudoalteromonas was also increased. Intestine mucus immune genes including mucin-2 and mucin-19 were up-regulated, while mucin-1 , mucin-5AC , and mucin-5B were down-regulated in two stress exposure groups. These results revealed that ammonia and nitrite stress harmed the intestine barrier function of L. vannamei by damaging the mucosal tissue, disrupting the composition of intestine microbial, and suppressing the immune function. Highlights • Impairment of the intestine barrier function in Litopenaeus vannamei exposed to ammonia and nitrite stress was studied. • Ammonia and nitrite stress damaged the intestine mucosal tissue. • Ammonia and nitrite stress decreased the intestine bacterial diversity. • Ammonia and nitrite stress disrupted the composition of intestine microbial. • Ammonia and nitrite stress influenced the intestine mucin genes expression. [ABSTRACT FROM AUTHOR]

Abstract Organic acids acts as an growth promoter and antimicrobial agent in aquaculture. The present study investigated the effects of a natural organic acid - succinic acid (SA) on the growth, digestive enzymes, immune response and resistance to ammonia stress of Litopenaeus vannamei. The shrimps were firstly fed with diets containing different levels of SA: 0% (Control), 0.25% (SA1), 0.50% (SA2), and 1.0% (SA3) ( w / w ) for 56 days, followed by an acute ammonia stress for 48 h. The results indicated that dietary of SA improved the growth of shrimp, and increased the survival rate of shrimp after ammonia stress for 48 h. The amylase, lipase and pepsin activity increased in hepatopancreas in three SA group, while trypsin activity was only increased in the SA1 and SA2 groups. At 56 d, T-NOS activity, proPO and HSP70 gene expression level increased in the three SA group, PO activity increased in the SA1 and SA2 groups, T-AOC content and Toll gene expression level increased in the SA2 and SA3 groups, Trx and SOD gene expression level increased in the SA2 group, while Imd , GS and GDH gene expression level was no changes. After exposure to ammonia stress for 48 h, immune biochemical parameters (T-AOC and PO) and genes ( proPO , HSP70 , Trx and GDH ) expression level increased in the three SA group, T-NOS activity, Toll , Imd and GS gene expression level increased in the SA2 and SA3 groups, while SOD gene expression level increased in the SA1 and SA2 groups. These results indicated that SA improved growth, enhanced digestive and immune capacities of L. vannamei against ammonia stress, and may be a potential feed additive for shrimp. The optimal dietary supplementation dosage is 0.50% ( w / w ) in diet. Highlights • Effects of dietary succinic acid (SA) supplementation in Litopenaeus vannamei was studied. • SA improved the growth performance and feed utilization of L. vannamei. • SA influenced the digestive enzymes of L. vannamei. • SA increased the immune capacity of L. vannamei resistance to ammonia stress. [ABSTRACT FROM AUTHOR]

The shrimp intestine barrier serves as the first line of the host defense against pathogen infection. Lipopolysaccharide (LPS) is the cell wall component of gram-negative bacteria, which known as endotoxin and induce the intestine inflammation. In this study, the acute toxicity effects of LPS injection on the morphology, digestive enzymes and immunological responses of intestine from Litopenaeus vannamei was investigated. HE stain showed that LPS injection damaged the intestine connective and epithelium tissue. Specifically, a decrease in the activities of digestive enzymes including of amylase, lipase, trypsin and pepsin was observed. Moreover, LPS injection increased the content of oxidative stress parameters ( O 2 − generation capacity, LPO, MDA and PC), and the expression of HIF-1α gene. Alternatively, the antibacterial activities (PO and T-NOS), and the expression of the antibacterial genes ( proPO , ALF , Toll and Imd ) and pathogen pattern recognition genes ( LGBP and Lec ) increased at first and then decreased. Significant variations in anitioxidant enzyme activity of T-AOC, and the expression of the anitioxidant-related genes ( SOD , HSP70 and Trx ). These results revealed that LPS injection harmed the intestine barrier of L. vannamei by damaging intestine mucosal structure, increasing oxidative stress, and suppressing the digestive and immune status. [ABSTRACT FROM AUTHOR]

Cryptocaryon irritans is a parasitic ciliate of marine fish, causing serious mortality and economic loss of grouper. In this study, the orange-spotted grouper (Epinephelus coioides) were separately exposed to C. irritan s infection for 72 h at a dose of 5000 or 10000 active theronts per fish, and we evaluated the changes in histopathology, oxidative stress, immune response, and intestinal microbiota composition. The results showed that C. irritan s infection caused pathological alteration on the skin, gills, and liver of E. coioides. Oxidative stress responses occurred in the liver and gills, reflected in the corresponding antioxidant enzyme and gene indexes. The mRNA expression levels of inflammation-related genes (IL-1β , IL-6 , and IL-8) and the mediators of apoptosis (casp3 , casp9 , and cytc) were increased in the liver and gills of the fish. C. irritans infection also affected the diversity and composition of intestinal microbiota. Specifically, the relative abundance of Firmicutes was increased, whereas that of Proteobacteria was decreased. Several potentially beneficial bacteria (Pandoraea , Clostridium sensu stricto 1 , Christensenellaceae R-7 group , and Weissella) were decreased, whereas pathogenic bacteria (Streptococcus and Acinetobacter) were increased. In conclusion, this study reveals that C. irritans infection caused histopathology, immune disorders, and intestinal microbial community variation in E. coioides. • C. irritan s infection caused pathological alteration in the skin, gills and liver of E. coioides. • C. irritan s infection caused oxidative stress, inflammation and apoptosis in the liver and gills of E. coioides. • C. irritan s infection altered the diversity and composition of intestinal microbiota of E. coioides. [ABSTRACT FROM AUTHOR]

The present study evaluated the effect of dietary Clostridium butyricum (CB) on growth, intestine microstructure, intestine digestive and immune function, intestine short-chain fatty acids (SCFA) content and body composition of Pacific white shrimp Litopenaeus vannamei . The shrimp was fed for 56 d with diets containing different levels of C. butyricum (1 × 10 9 cfu/g): 0% (Control), 0.25% (CB1), 0.5% (CB2) and 1.0% (CB3) as treatment groups, followed by an acute ammonia stress test for 72 h. The results indicated that dietary supplementation of C. butyricum decreased the feed conversion rate (FCR) and increased the growth performance of shrimp. Compared with the control group, after shrimp fed with C. butyricum 56 d, intestine amylase and protease activity in the three C. butyricum group increased, while lipase activity was only affected in the CB1 and CB2 group. Total antioxidant capacity (T-AOC) content, lysozyme (LSZ) activity, and the relative expression level of Toll and immune deficiency (Imd) gene all increased in three C. butyricum groups. Inducible nitric oxide synthase (iNOS) activity increased in the CB2 and CB3 group, heat shock protein 70 (HSP70) gene expression level increased in the CB3 group, while nitric oxide (NO) content was not affected by C. butyricum . After shrimp exposed to ammonia stress, intestine immune biochemical parameters (T-AOC, LSZ, iNOS and NO) and genes (HSP70, Toll and Imd) expression level of C. butyricum group was higher than that of the control. HE stain showed that C. butyricum increased the intestine epithelium height of L. vannamei . These results revealed that C. butyricum could improve the growth performance, increased intestine SCFA content and body crude protein content, modulated intestine digestive capacity, and enhanced intestine immune function of L. vannamei against ammonia stress. [ABSTRACT FROM AUTHOR]

A 56-day feeding trial followed by an acute high temperature stress test were performed to evaluate the effect of dietary probiotic Clostridium butyricum (CB) on growth performance and intestine antioxidant capacity of kuruma shrimp Marsupenaeus japonicus . Shrimp were randomly allocated in 9 tanks (30 shrimp per tank) and triplicate tanks were fed with diets containing different levels of C. butyricum (1×10 9 cfu/g): 0 mg g −1 feed (Control), 100 mg g −1 feed (CB-100), 200 mg g −1 feed (CB-200) as treatment groups. The results indicated that dietary supplementation of C. butyricum increased the growth performance and decreased the feed conversion rate (FCR) of shrimp in the CB-100 group. HE stain showed that C. butyricum increased the intestine epithelium height of M. japonicus. C. butyricum supplemented in diets decreased·O 2 - generation capacity and malondialdehyde (MDA) content, and increased total antioxidant capacity (T-AOC), catalase (CAT) and peroxidase (POD) activity and the expression level of heat shock protein 70 ( hsp70 ) and metallothionein ( mt ) gene in intestine of shrimp cultured under normal condition for 56 d, while no significant changes in glutathione peroxidase (GPx) activity and ferritin gene expression level. After shrimp exposed to high temperature stress 48 h, the lower level of·O 2 - generation capacity and MDA content, and the higher level survival, activities of T-AOC, CAT, GPx and POD, as well as hsp70 , ferritin and mt gene expression level were found in intestine of two C. butyricum groups. These results revealed that C. butyricum could improve the growth performance, increase intestine antioxidant capacity of M. japonicus against high temperature stress, and could be a potential feed additive in shrimp aquaculture. [ABSTRACT FROM AUTHOR]

The effects of sulfide stress on oxidative stress and immune response in intestine of Pacific white shrimp Litopenaeus vannamei were evaluated in the present study. Oxidative stress parameters, immune enzymes activity and immune gene mRNA expression level were detected in intestine of L. vannamei after the exposure of 5.0 mg/L sulfide stress 72 h. The duration of sulfide stress influenced the shrimp survival, and the cumulative mortality rate was 30.0% and 33.3% at 48 h and 72 h respectively. HE staining showed that sulfide stress caused the intestine tissue damage symptoms. Compared with the control group, after exposed to sulfide stress, the content of lipid peroxidation (LPO), malondialdehyde (MDA) and ROS production (·O 2 − generation capacity) increased. Total antioxidant capacity (T-AOC) activity increased at 6 h and decreased at 48 h. Superoxide dismutase (SOD) activity increased in the entire experiment. Inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) content increased to the highest at 6 h and 12 h respectively, and both decreased at 48 h. The relative mRNA expression level of heat shock protein 70 (HSP70) gene decreased at 6 h and increased to the highest at 48 h. The relative mRNA expression level of hypoxia inducible factor 1α (HIF-1α) gene increased at 12 h and decreased to a lower level at 72 h. The relative mRNA expression level of Toll and immune deficiency (Imd) gene increased to the highest at 12 h and 24 h respectively, and both decreased at 48 h. These results revealed that sulfide stress could induce oxidative stress and immune response via confusion of immune enzymes activity and gene expression level in intestine of L. vannamei . [ABSTRACT FROM AUTHOR]

A 45-day feeding trial followed by an acute stress test of low salinity was done to evaluate effects of Lactobacillus plantarum on growth performance and anti-stress capability of white shrimp ( Litopenaeus vannamei) . Shrimp were randomly allocated in 15 tanks (100 shrimp per tank) and divided into 5 treatments with 3 replicates. Triplicate tanks were fed with a control diet or diets containing different treatments of L. plantarum (fermentation supernatant (FS), live bacteria (LB), dead bacteria (DB) and cell-free extract (CE) of L. plantarum ) as treatment groups. Growth performance including weight gain (WGR), feed conversion ratio (FCR) and specific growth rate (SGR) were determined after feeding 45 days. Anti-stress capacity was evaluated by determining the gene expression of ProPO, SOD and Lys in gut of shrimp at the end of feeding trial and again at 96 h post-stress test. Results indicated that supplementation of L. plantarum into diet had significantly improved growth performance of L. vannamei . On the other hand, L. plantarum supplementation had no significant effects on the gene expression of SOD and Lys in gut of shrimp cultured under normal condition for 45 days. Supplementation of L. plantarum had increased survivability of L. vannamei having higher survival rates compared to the control group. However, statistical analysis showed no significant difference between the control group and treatments. Compared with the control group, supplementation of L. plantarum significantly improved the resistance of L. vannamei against the stress of acute low salinity, as indicated by higher survival rate as well as higher transcript levels of ProPo, SOD and Lys gene. Our findings suggested that L. plantarum , especially cell-free extract of L. plantarum has improved the anti-stress capacity of L. vannamei and could serve as a potential feed additive that helps shrimp to overcome environmental stresses. [ABSTRACT FROM AUTHOR]

In the present study, the effect of dietary supplementation of poly-β-hydroxybutyrate (PHB) on the growth performance, intestinal digestive and immune function, intestinal short-chain fatty acids (SCFA) content and body composition of Pacific white shrimp Litopenaeus vannamei (Boone, 1931) was evaluated. The shrimp was fed for 35 days with four different diets: 0%, 1%, 3% and 5% PHB supplemented feed. The results indicated that supplementation of PHB significantly increased the growth performance of the shrimp, and the feed conversion rate (FCR) in 3%PHB treatment group was significantly lower than the control ( P < 0.05). The intestinal amylase, lipase and trypsin activity in the three PHB treatment groups were all significantly higher than that of the control ( P < 0.05), but the pepsin activity were only significantly affected by 3%PHB treatment ( P > 0.05). The activities of intestinal immune enzymes such as total antioxidant capacity (T-AOC) and inducible nitric oxide synthase (iNOS) was significantly induced by 3%PHB treatment ( P < 0.05), while lysozyme (LSZ) activity was significantly affected by 5%PHB treatment and nitric oxide (NO) content was significantly induced in three PHB treatments. Meanwhile, PHB induced significantly the expression level of intestinal heat shock protein 70 (HSP70), Toll and immune deficiency (Imd) gene. HE staining showed that PHB induced the intestinal health status of L. vannamei . Intestinal SCFA content analysis revealed that the content of propionic and butyric acid of 3%PHB treatment were significantly higher than that of the control ( P < 0.05). Body composition analysis showed that the crude protein in 3% and 5%PHB treatments, and the crude lipid in 1% and 5%PHB treatments were all significantly higher than the control ( P < 0.05). These results revealed that PHB could improve the growth performance, modulated intestinal digestive and immune function, increased intestinal SCFA content and body composition in L. vannamei , and the optimum dietary PHB requirement by L. vannamei was estimated at 3% ( w / w ) diet. [ABSTRACT FROM AUTHOR]

In the present study, the oxidative stress and antioxidant response in hepatopancreas of the black tiger shrimp Penaeus monodon under desiccation stress were studied, such as activities of antioxidant enzymes (SOD, CAT, GPx and POD), oxidative damage to lipid and protein which indexed by contents of LPO, MDA, protein carbonyl (PC) and ROS production, and the expression of HSP70 and ferritin gene. The duration of desiccation significantly influenced the shrimp survival, and the mortality rates were 10% and 55.0% after desiccation 0.5 h and 3 h, respectively. Compared with the control group, after exposed to desiccation stress, the content of LPO, MDA, PC and ROS production in hepatopancreas increased significantly. SOD, CAT and POD activity in hepatopancreas increased significantly at 0.5 h, but decreased markedly at 1 h. GPx activity in hepatopancreas increased significantly at 0.5 h and 1 h, then decreased significantly at 3 h. The transcript levels of HSP70 and ferritin gene in hepatopancreas increased significantly at 1 h. HE staining showed that desiccation induced damage symptoms in hepatopancreas of P. monodon . These results revealed that desiccation could induce oxidative stress and antioxidant response via confusion of antioxidant enzymes activity and gene transcript level in hepatopancreas of P. monodon , and the time of shrimp under desiccation should lower than 0.5 h. [ABSTRACT FROM AUTHOR]

ADP ribosylation factors (Arf), as highly conserved small guanosine triphosphate (GTP)-binding proteins, participates in intracellular trafficking and organelle structure. In this study, a full-length cDNA of Arf1 (designated EcArf1) was cloned from Exopalaemon carinicauda by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcArf1 was 1428 bp, which contains an open reading frame (ORF) of 549 bp, encoding a 182 amino-acid polypeptide with the predicted molecular weight of 20.69 kDa and estimated isoelectric point was 7.24. Sequence analysis revealed that the conserved Arf protein family signatures were identified in EcArf1. The deduced amino acid sequence of EcArf1 shared high identity (95%–98%) with that of other species and clustered together with Arf1 of other shrimp in the NJ phylogenetic tree, indicating that EcArf1 should be a member of the Arf1 family. Quantitative real-time RT-qPCR analysis indicated that EcArf1 was expressed in hemocytes, hepatopancreas, gills, muscle, ovary, intestine, stomach and heart, and the most abundant level was in hemocytes and gills, which were also the two main target tissues of pathogen infection and environmental stress. After Vibrio parahaemolyticus challenge, EcArf1 transcripts level significantly increased in hemocytes and hepatopancreas at 3 h and 6 h, respectively. The expression of EcArf1 in hemocytes and hepatopancreas significantly up-regulated at 12 h and 6 h respectively, and down-regulated at 72 h and 48 h, respectively. EcArf1 expression in hepatopancreas and gills both significantly increased at 6 h and decreased at 24 h under ammonia-N stress. The results suggested that EcArf1 might be involved in immune responses to pathogens ( V. parahaemolyticus and WSSV) challenge and ammonia-N stress in E. carinicauda . [ABSTRACT FROM AUTHOR]

In the present study, the oxidative stress response in hepatopancreas of Marsupenaeus japonicus to desiccation stress and resubmersed in seawater were studied, such as respiratory burst, ROS production ( ⋅ O 2 − ), activities of antioxidant enzymes (CAT, GPx, SOD, POD and GST) and oxidative damage to lipid and protein (indexed by contents of MDA). The duration of desiccation significantly influenced shrimp survival, and the mortality rates were 37.5% and 87.5% after desiccation 5 h and 10 h, respectively. After desiccation stress 3 h, the respiratory burst, ROS production, and the activity of SOD and CAT were up-regulated significantly. The activity of GPx and POD, and the content of MDA decreased significantly at 0.5 h and 1 h, and then increased significantly at 3 h. But GST activity was no significant change after desiccation. During the resubmersion period, most of the antioxidant enzymes activities could recover to the control level at 24 h, but a small quantity of the oxidative stress still existed in tissues. HE staining showed that desiccation stress induced damage symptoms in hepatopancreas of M. japonicus . These results revealed that desiccation influenced the antioxidative status and caused oxidative stress and tissue damage via confusion of antioxidant enzymes in M. japonicus , but the oxidative stress could be eliminated within a certain range after the shrimps were resubmersed in seawater. [ABSTRACT FROM AUTHOR]

Oncoprotein NM23, as a family of genes encoding the nucleoside diphosphate (NDP) kinase, plays important roles in bioenergetics, DNA replication, differentiation and tumor metastasis. In this study, a full-length cDNA of NM23 (designated EcNM23) was cloned from Exopalaemon carinicauda by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcNM23 was 755 bp, which contains an open reading frame (ORF) of 518 bp, encoding a 175 amino-acid polypeptide with the predicted molecular weight of 19.60 kDa and estimated isoelectric point of 7.67. The deduced amino acid sequence of EcNM23 shared high identity (86%–93%) with that of other crustaceans. a NDP kinase super family signature was identified in E. carinicauda EcNM23. Quantitative real-time RT-qPCR analysis indicated that EcNM23 was expressed in all the examined tissues with the high expression level in hemocytes and ovary. The EcNM23 expression in immune-related tissues changed rapidly and reached peak at different time after pathogens ( Vibrio parahaemolyticus and WSSV) challenge and ammonia-N stress treatment. The results suggested that EcNM23 might be associated with the immune defenses to pathogens infection and ammonia-N stress in E. carinicauda . [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is a virulent pathogen that affects shrimp aquaculture. Reactive oxygen species are produced by the immune system that defends the host against foreign microorganisms. In the present study, the oxidative stress response in hepatopancreas and gills of Penaeus monodon to V. parahaemolyticus challenge were studied, such as respiratory burst, ROS production (·O 2 − and ·OH), activities of antioxidant enzymes (CAT, GPx, SOD, POD and GST) and oxidative damage to lipid and protein (indexed by contents of MDA). Compared with the control group, after V. parahaemolyticus challenge, respiratory burst and ROS production were up-regulated significantly. GPx and POD activity increased significantly in hepatopancreas and gills of the shrimps at 12 h, but CAT activity decreased markedly at 12 h and 24 h. SOD and GST activity in hepatopancreas of the shrimps increased significantly at 1.5 h, but decreased markedly at 12 h–48 h. MDA content increased significantly after 6 h–24 h challenge. HE staining showed that V. parahaemolyticus challenge induced damage symptoms in hepatopancreas of P. monodon . Our study revealed that V. parahaemolyticus influenced the antioxidative status and caused oxidative stress and tissue damage via confusion of antioxidant enzymes in P. monodon . [ABSTRACT FROM AUTHOR]

The harmful effects of microcystin-LR (MC-LR) stress are unavoidable in shrimp culture. Arachidonic acid (AA) is a fatty acid that regulates immune responses in aquatic animals. In this study, we investigated the effects of dietary AA on growth, immunity and intestinal microbiota of Litopenaeus vannamei under MC-LR stress. The shrimp were fed a control diet (non-supplemented with AA) or a AA diet (supplemented with 8.0 g/kg AA) for 56 days, followed by an acute MC-LR stress for 72 h. The results showed that dietary AA improved the growth and feed utilization of the shrimp. Microcystin-LR exposure increased the mRNA expressions of reactive oxygen species modulator 1 (ROMO1), glutathione peroxidase (GPx), caspase-3 (Casp-3), NADPH-cytochrome P450 reductase (NCPR) and sulfotransferase (SULT), but decreased that of catalase (CAT) and cytochrome C (Cytc). Dietary AA supplementation reversed the expressions of ROMO1 , CAT , GPx and NCPR to the control level, but still maintained the higher levels of Cytc , Casp-3 and SULT than the control and MC-LR stress groups. Dietary AA could not effectively reverse the changes of intestinal microbial diversity, but it could improve intestinal microbial composition variation induced by MC-LR stress. Specially, dietary AA increased the relative abundances of beneficial bacteria Bacteroides and Lactobacillus , and reversed the changes of pathogenic bacteria Vibrio and Photobacterium induced by MC-LR stress to the control level. The changes of intestinal bacteria were correlated with immune gene expression. These results revealed that dietary AA had a positive effect on L. vannamei resistance to MC-LR stress by modulating immune response and intestinal microbial composition. • Dietary AA modulated the immune responses of the shrimp resistance to MC-LR stress. • Dietary AA altered intestinal microbial composition variation induced by MC-LR stress. • Dietary AA increased the abundance of intestinal beneficial bacteria. • The changes of intestinal bacteria were correlated with immune gene expression. [ABSTRACT FROM AUTHOR]

Abstract: Calreticulin (CRT), as a highly conserved endoplasmic reticulum luminal resident protein, plays important roles in Ca2+ homeostasis, molecular chaperoning and response to viral infection. In this study, a full-length cDNA of CRT (designated EcCRT) was cloned from hemocytes of the ridgetail white prawn Exopalaemon carinicauda by using rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcCRT was 1725 bp, which contains a 5′-untranslated region (UTR) of 57 bp, 3′-UTR of 453 bp with a poly (A) tail, an open reading frame (ORF) of 1215 bp, encoding a 404 amino-acid polypeptide with the predicted molecular weight of 46.51 kDa and estimated isoelectric point of 4.32. The deduced amino acid sequence of EcCRT shared high identity (82%–85%) with that of other crustaceans. Phylogenetic analysis showed that EcCRT of E. carinicauda was clustered together with CRT of other shrimps, indicating that EcCRT should be a member of the CRT family. Quantitative real-time RT-qPCR analysis indicated that EcCRT was expressed in hemocytes, gill, hepatopancreas, muscle, ovary, intestine, stomach and eyestalk, with the highest expression level in hemocytes. After Vibrio anguillarum and WSSV challenge, the expression level of EcCRT transcripts both in the hemocytes and hepatopancreas of E. carinicauda were up-regulated in the first 6 h, respectively. The results suggested that EcCRT might be associated with the immune defenses to V. anguillarum and WSSV in E. carinicauda. [Copyright &y& Elsevier]

Abstract: A selenium-dependent glutathione peroxidase cDNA was obtained from the ridgetail white prawn Exopalaemon carinicauda (EcGPx) by rapid amplification of cDNA ends (RACE) methods. The full-length cDNA of EcGPx was 946 bp, which contains a 5′-untranslated region (UTR) of 105 bp, 3′-UTR of 280 bp with a poly (A) tail, an open reading frame (ORF) of 561 bp, encoding a 186 amino-acid polypeptide with the predicted molecular weight of 21.35 kDa and estimated isoelectric point of 7.65. It involves a putative selenocysteine (U39) residue which is encoded by an opal codon, 220TGA222, and forms an active site with residues Q73 and W141. Sequence analysis revealed that a GPx signature motif 2 (63LAFPCNQF70), an extra active site motif (151WNFEKF156), two putative N-glycosylation site (75NNT77 and 107NGS109), and two arginine residues (R89 and R167) were observed in the EcGPx sequence. Comparison of amino acid sequences showed that white shrimp GPx is more closely related to GPx1 and GPx2 subgroups. Quantitative real-time RT-PCR analysis indicated that two glutathione antioxidant enzymes of E. carinicauda, glutathione peroxidase (designated EcGPx) and glutathione S-transferase (designated EcGST) were widely expressed in all the tested tissues, but showed different expression patterns. After Vibrio anguillarum and WSSV challenge, EcGPx and EcGST transcripts both in hemocytes and hepatopancreas increased in the first 6 h and 3 h, respectively. The results suggested that EcGPx and EcGST might be associated with the immune defenses to V. anguillarum and WSSV in E. carinicauda. [Copyright &y& Elsevier]

Abstract: The ridgetail white prawn Exopalaemon carinicauda is one of the most important commercial species in eastern China. However, little information of immune genes in E. carinicauda has been reported. To identify distinctive genes associated with immunity, an expressed sequence tag (EST) library was constructed from hemocytes of E. carinicauda. A total of 3411 clones were sequenced, yielding 2853 ESTs and the average sequence length is 436 bp. The cluster and assembly analysis yielded 1053 unique sequences including 329 contigs and 724 singletons. Blast analysis identified 593 (56.3%) of the unique sequences as orthologs of genes from other organisms (E-value < 1e-5). Based on the COG and Gene Ontology (GO), 593 unique sequences were classified. Through comparison with previous studies, 153 genes assembled from 367 ESTs have been identified as possibly involved in defense or immune functions. These genes are categorized into seven categories according to their putative functions in shrimp immune system: antimicrobial peptides, prophenoloxidase activating system, antioxidant defense systems, chaperone proteins, clottable proteins, pattern recognition receptors and other immune-related genes. According to EST abundance, the major immune-related genes were thioredoxin (141, 4.94% of all ESTs) and calmodulin (14, 0.49% of all ESTs). The EST sequences of E. carinicauda hemocytes provide important information of the immune system and lay the groundwork for development of molecular markers related to disease resistance in prawn species. [Copyright &y& Elsevier]

Enterocytozoon hepatopenaei (EHP) is a parasite that causes hepatopancreatic microsporidiosis and is associated with shrimp growth retardation. The intestinal bacterial is an important biological barrier against pathogen invasion. In this study, we investigated the intestinal bacterial and hepatopancreas transcriptome responses of Litopenaeus vannamei to natural EHP infection. Compared with the healthy group, obvious changes in the intestinal bacterial were caused by EHP infection, with significantly increased relative abundance of Chloroflexi and decreased relative abundance of Bacteroidetes. Several genera of bacteria with putatively beneficial substance-producing characteristics were reduced in the diseased group, such as Alloprevotella , Bacillus , Bacteroides , Weissella , and Pandoraea. The hepatopancreas transcriptome revealed differentially expressed genes mainly associated with carbohydrate digestion and absorption, and some immune-related genes associated with antimicrobial processes were downregulated in contrasting accessions. Bacillus had the mostly positive correlation with gene markers; Tryp and Fer2 had positive correlation with intestinal bacteria, but APOD, FABP and HSP67 had negative correlation with them. These results revealed that EHP infection causes intestinal bacterial variation and influences the nutrition metabolism and immunity of L. vannamei. • Intestinal microbiota and hepatopancreas gene transcription were influenced. • Several intestinal beneficial substance producing bacteria genera were deduced. • Hepatopancreas carbohydrate digestion and absorption was altered. • Some immune and metabolism-related gene markers were identified. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are a hazardous pollutant of world concern that threaten aquatic organisms and ecosystems. In this study, we chose the worldwide-distributed shrimp Litopenaeus vannamei as a model and investigated the toxicological effects of five types of MPs on L. vannamei using several omics approaches. After 14 days of exposure to MPs, obvious intestinal microbiota variation was observed, such as increased abundances of Bacteroidetes and Proteobacteria and a decreased abundance of Firmicutes. Specifically, MPs induced several putative opportunistic pathogens and reduced lactic acid- and short-chain fatty acid-producing bacteria. Alternatively, MPs altered haemolymph proteome profiles, but the five types of MPs had different effects on the enriched pathways and the expression of immune-related proteins. Furthermore, MPs also caused haemolymph metabolite variation, especially in amino acid and alpha-linolenic acid metabolism, and 28 differential metabolites were altered in the five MP-treated groups. Changes in intestinal bacteria were correlated with the haemolymph proteins and metabolites of the shrimp. Overall, these results reveal the toxicological effects of MPs on the intestinal microbiota and the host's immunity and metabolism in shrimp. Unlabelled Image • Intestinal microbiota and haemolymph protein and metabolite molecules were affected. • Intestinal lactic acid and short chain fatty acid producing bacteria abundance were decreased. • Different types of MPs changed haemolymph protein profiles differently. • Haemolymph amino acids and alpha-linolenic acid metabolism were altered. • Several stress-related protein and metabolite markers were identified. [ABSTRACT FROM AUTHOR]

Ammonia and thermal stress frequently have harmful effects on aquatic animals. The intestine is an important barrier allowing the body to defend against stress. In this study, we investigated the intestinal microbiota and transcriptomic and metabolomic responses of Litopenaeus vannamei subjected to individual and combined ammonia and thermal stress. The results showed that obvious variation in the intestinal microbiota was observed after stress exposure, with increased levels of Firmicutes and decreased levels of Bacteroidetes and Planctomycetes. Several genera of putatively beneficial bacteria (Demequina , Weissella and Bacteroides) were abundant, while Formosa , Kriegella , Ruegeria , Rhodopirellula and Lutimonas were decreased; pathogenic bacteria of the genus Vibrio were increased under individual stress but decreased under combined stress. The intestinal transcriptome revealed several immune-related differentially expressed genes associated with the peritrophic membrane and antimicrobial processes in contrasting accessions. Haemolymph metabolomic analysis showed that stress exposure disturbed the metabolic processes of the shrimp, especially amino acid metabolism. This study provides insight into the underlying mechanisms associated with the intestinal microbiota, immunity and metabolism of L. vannamei in response to ammonia and thermal stress; ten stress-related metabolite markers were identified, including L-lactic acid, gulonic acid, docosahexaenoic acid, l -lysine, gamma-aminobutyric acid, methylmalonic acid, trans-cinnamate, N -acetylserotonin, adenine, and dihydrouracil. Unlabelled Image • Intestinal microbiota and immune molecules, and haemolymph metabolism were disrupted. • Intestinal Firmicutes abundance was increased but Bacteroidetes abundances was decreased. • Intestinal peritrophic membrane and antimicrobial genes were differentially expressed. • Haemolymph amino acid and arachidonic acid metabolism were disturbed. • Several stress-related gene and metabolite markers were identified. [ABSTRACT FROM AUTHOR]

Microcystis aeruginosa bloom in aquatic ecosystems is a worldwide problem that threaten aquatic animals. Fish are an unavoidable link between toxic cyanobacteria and human health. A stable microbiota is an important barrier for fish in defence against pathogen invasion. Therefore, in this study, we investigated the microbiota characteristics in different parts of the gastrointestinal tract and faeces of Lateolabrax maculatus that were cultured in a pond with a naturally occurring M. aeruginosa bloom. Compared with those of the healthy fish, the cyanobacterial bloom decreased the serum immune indexes of the diseased fish, such as the immunoglobulin M content and lysozyme activity. Microbiome analysis showed that the M. aeruginosa bloom did not change the microbial richness and diversity of the diseased fish but significantly altered the community composition. Specifically, M. aeruginosa bloom increased the abundance of Proteobacteria but decreased the abundance of Firmicutes; some genera of pathogenic bacteria (Acinetobacter , Mycobacterium and Staphylococcus) were abundant, while some beneficial bacteria (Weissella and Lactococcus) were reduced. Our results reveal that M. aeruginosa bloom significantly impair the immunity and gastrointestinal microbiota composition of L. maculatus and that microbiota variation may be a factor causing almost all fishes exhibit unhealthy or diseased characteristics. These results will be helpful for the utilization of microbiome characteristics to facilitate healthy fish farming in cyanobacterial bloom environments. • We analysed the gastrointestinal microbiota of Lateolabrax maculatus in a Microcystis aeruginosa bloom environment. • M. aeruginosa bloom decreased the immunoglobulin M content and lysozyme activity in the fish serum. • M. aeruginosa bloom did not change the microbial richness and diversity of the fish. • M. aeruginosa bloom increased the abundance of Proteobacteria but decreased the abundance of Firmicutes. • Dysbacteriosis may be a factor causing almost all fishes exhibit unhealthy or diseased characteristics. [ABSTRACT FROM AUTHOR]

Along with the intensification of culture systems to meet the increasing global demands, there is an elevated risk of disease outbreak and substantial loss for shrimp farmers. Probiotics, e.g., Lactobacillus plantarum , are among the most promising feed supplements for controlling or treating microbial diseases in shrimp aquaculture. The maintenance of live and viable probiotic bacterial culture during storage is, however, quite challenging. This study investigated the paraprobiotic potential of L. plantarum on whiteleg shrimp (Penaeus vannamei), specifically on the intestinal microbiota. Four different experimental diet preparations of L. plantarum (fermentation supernatant (FS), live bacteria (LB), dead bacteria (DB), and cell-free extract (CE)) were used in the 15-day feeding trial. Subsequently, 16S rDNA gene sequencing technology was applied to analyze and characterize the whiteleg shrimp intestinal microbiota. Results showed that Proteobacteria was the most prevalent phylum in whiteleg shrimp gut microbiota, independent of the diet. Other phyla, including Bacteroidetes, Verrucomicrobia, Tenericutes, and Euryarchaeota were also recorded and independent of the diet. The microbiota of the whiteleg shrimp fed with the L. plantarum CE diet showed the highest abundance of Acidobacteria, with a 70-fold increase compared to that of the animals on the control diet. The abundance of Verrucomicrobia was the highest in the whiteleg shrimp fed with L. plantarum DB diet. Moreover, the abundance of Cyanobacteria, Crenarcheota, and Euryarchaeota in the microbiota of animals fed with L. plantarum FS diet were more than 10-fold higher, compared to that of the whiteleg shrimp fed with the control diet. An increased number of the potential beneficial bacteria from the genera Demequina , Rubritalea , Tenacibaculum , Marinicella and Phaeobacter versus a significantly decreased amount of the potential pathogenic genus Synechococcus were encountered in the microbiota of the CE diet-fed animals. There were 382 operational taxonomic units (OTUs) shared among all gut samples. The microbiota of the shrimps on the CE diet had the most unique OTUs, followed by those included in the FS and DB diet groups. These results demonstrated that P. vannamei fed with L. plantarum CE and FS diets had a significantly altered gastrointestinal microbiota. In conclusion, L. plantarum CE and FS diets have the potential to be used as paraprobiotics, due to the capacity to positively modulate the gastrointestinal microbiota in P. vannamei. • Four different preparation of L. plantarum groups increased the abundance of Acidobacteria. • The potential beneficial bacteria were enriched in the cell-free extract of L. plantarum group. • The composition and diversity of shrimp intestinal microbiota varied in different preparations of L. plantarum [ABSTRACT FROM AUTHOR]

Succinate (SA) is the precursor of propionate that influence the intestine physiological function of animals. In this study, we investigated the microbiome, digestive, and immune responses in the intestines of Pacific white shrimp Litopenaeus vannamei fed diets containing different levels of SA: 0 g/kg (Control), 2.5 g/kg (SA1), 5.0 g/kg (SA2), and 10.0 g/kg (SA3) for 56 days. The results showed that dietary SA improved the intestine mucosa morphology, increased the short-chain fatty acids contents, and altered the intestine microbiota composition. Specifically, SA increased the abundances of Proteobacteria and decreased the abundance of Bacteroidetes. The beneficial bacteria including Ruegeria , Lutimonas , Mameliella , and Sphingomonas were enriched in response to dietary SA; these genus might be involved in nutrient metabolism and the degradation of toxic compounds and pollutants. Additionally, dietary SA also improved the activity of digestive enzymes (amylase, lipase, trypsin, and pepsin) and immune enzymes (total antioxidant capacity, phenoloxidase, total nitric oxide synthase, and nitric oxide), and the expression of immune-related genes (prophenoloxidase, anti-lipopolysaccharide factor, lysozyme, heat shock protein 70, thioredoxin, mucin-1, mucin-2, mucin-5 AC, mucin-5B, and mucin-19) in the intestine of the shrimp. These results revealed that dietary SA had a positive effect on the intestine health of L. vannamei by modulating the microbial composition and SCFA contents, and enhancing the digestive and immune response in the shrimp intestine. • Effects of dietary succinate (SA) on the intestine health of Litopenaeus vannamei was studied. • Dietary SA increased intestine mucosa morphology. • Dietary SA altered the microbiota composition and increased the intestine SCFA contents. • Dietary SA induced digestive and immune response in the intestines of L. vannamei. • The changes of biochemical parameters were correlated with the bacterial abundance. [ABSTRACT FROM AUTHOR]

Simple Summary: Seaweeds and probiotics are commonly utilized as additives in the diet of aquatic animals. However, limited information exists regarding the effects of Gracilaria lichenoides and Bacillus amyloliquefaciens, either alone or in combination, on Penaeus monodon. In our study, we examined the impact of dietary supplementation with G. lichenoides and B. amyloliquefaciens, both individually and in combination, on the growth performance, antioxidant capacity, and intestinal function of P. monodon. Our findings indicate a beneficial influence of dietary G. lichenoides and B. amyloliquefaciens on P. monodon. These findings offer a theoretical foundation for the judicious utilization of G. lichenoides and B. amyloliquefaciens in the cultivation of black tiger shrimp, as well as for future investigations into their metabolic mechanisms. This research sought to assess the effects of dietary supplements with Gracilaria lichenoides and Bacillus amyloliquefaciens, either individually or combined, on the growth performance, antioxidant capacity, and intestinal function of Penaeus monodon. A total of 840 shrimps were randomly assigned to 28 tanks with an average initial weight of (1.04 ± 0.03) g (30 shrimp per tank) with 7 different treatment groups and 4 replicates per treatment. The control treatment (C) consisted of a basal diet; in contrast, the experimental groups were complement with varying levels of G. lichenoides (3% or 8%), either alone (S3 and S8) or in combination with B.amyloliquefaciens at different concentrations (3% G. lichenoides and 109 CFU/g—S3B9; 8% G. lichenoides and 1011 CFU/g B. amyloliquefaciens—S8B11; 109 CFU/g B. amyloliquefaciens—S9; 1011 CFU/g B. amyloliquefaciens—B11). The results indicated that the maximum values of final body weight (FBW) (10.49 ± 0.90) g, weight gain rate (WGR) (908.94 ± 33.58) g, and specific growth rate (SGR) (4.20 ± 0.06) g were perceived in the 3% G. lichenoide diet treatment, and compared with the control group, the difference was significant (p < 0.05). The whole-body lipid content of shrimp in the B9 group was significantly higher than that in the B11 group (p < 0.05), but no significant difference was observed when compared with shrimp fed other diets (p > 0.05). The ash content of shrimp in the B9 group was found to be significantly higher than that in the S3B9 group (p < 0.05). Furthermore, the lipase activity in the stomach and intestines of the experimental groups exhibited a statistically significantly increase compared to the control (p < 0.05). In comparison to the control group, the hepatopancreas of the S3 group exhibited a significant increase in the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and antioxidant genes [SOD, catalase (CAT), GSH-Px, thioredoxin (Trx), Hippo, and NF-E2-related factor 2 (Nrf2)] expression levels (p < 0.05). Additionally, the activities of total antioxidant capacity (T-AOC), SOD, peroxidase (POD), and antioxidant genes (CAT, GSH-Px, Trx, and Hippo) in the S3B9 treatment of hepatopancreas showed significant improvement (p < 0.05). The inclusion of dietary G. lichenoides and B. amyloliquefaciens resulted in enhanced relative expression of intestinal lipid metabolism genes (fatty acid synthetase (FAS), lipophorin receptor (LR), fatty acid transport protein 1 (FATP1)) and suppressed the expression of the long-chain fatty acid-CoA ligase 4 (LCL4) gene. Analysis of microbiota sequencing indicated improvements in composition and structure, with notable increases in Firmicutes at the phylum level and Vibrio at the genus level in the S3 group, as well as an increase in Tenericutes at the genus level in the S8B11 group. Overall, the inclusion of dietary G. lichenoides and B. amyloliquefaciens positively impacted the growth, antioxidant capacity, and microbial composition of shrimp, with particular enhancement observed in shrimp fed a supplementary 3% G. lichenoides diet. [ABSTRACT FROM AUTHOR]

The rabbitfish Siganus oramin is an important naturally caught and aquaculture fish species. Intestinal microbiota can affect the metabolism and immunity of fish, which is closely related to the habitat of the host. In this study, we collected the wild fry S. oramin from a natural sea area, and cultured them in outdoor and indoor ponds, respectively, and investigated the changes in serum biochemical indexes and intestinal microbial community in three different habitats. The results showed that compared with the wild population, the serum total protein content of the outdoor culture population increased significantly. The indoor culture population had significantly higher triglyceride and total cholesterol contents than that of the outdoor culture population. Additionally, the intestinal microbial richness indexes ACE and Chao1 of the cultured population were higher than those of the wild population, especially the indoor culture, but Shannon and Simpson had no obvious changes. The relative abundances of Firmicutes, Spirochaetae and Bacteroidetes increased in the outdoor culture population, but decreased in the indoor culture population; those of Proteobacteria and Cyanobacteria were completely the opposite. Some putative beneficial bacteria (Lactobacillus, Clostridium sensu stricto 1, and Intestinibacter) and harmful bacteria (Vibrio, Photobacterium, Desulfovibrio, Streptococcus) all decreased in the intestines of the cultured population when compared with the wild population, while Akkermansia and Faecalibacterium were enriched in the outdoor culture population. These results reveal that a change in habitat environment, whether an outdoor or an indoor pond, positively influenced the intestinal microbiota of the rabbitfish, which is beneficial to the healthy culture of the fish from the perspective of microbial community. [ABSTRACT FROM AUTHOR]

Simple Summary: Fly maggots are nutrient-rich, especially with regard to their protein content, making them an ideal replacement for the more expensive fishmeal. We aimed to analyse the effects of different treatments (i.e., fresh fly and fermented fly maggot protein feed, and fermented fly maggot protein feed with high-temperature pelleting) of fly maggot protein feed on the growth and intestinal flora of Pacific white shrimp (Litopenaeus vannamei). Fresh fly maggot protein in the feed was detrimental to shrimp growth, whereas fermented and high-temperature pelleted fly maggot protein feeds improved shrimp growth and survival. In addition, the fermented and high-temperature pelleted fly maggot protein feed increased the abundance of beneficial bacteria in shrimp intestines and reduced the growth of harmful bacteria. In contrast, fresh fly maggot proteins led to invasion by Vibrio as well as antibiotic-resistant bacteria. This study contributes to our understanding of the regulatory effects of different treatments on the growth and intestinal microflora of L. vannamei and provides a basis for the use of fly maggots as a source of protein in the context of aquaculture. As the intensive development of aquaculture persists, the demand for fishmeal continues to grow; however, since fishery resources are limited, the price of fishmeal remains high. Therefore, there is an urgent need to develop new sources of protein. They are rich in proteins, fatty acids, amino acids, chitin, vitamins, minerals, and antibacterial substances. Maggot meal-based diet is an ideal source of high-quality animal protein and a new type of protein-based immune enhancer with good application prospects in animal husbandry and aquaculture. In the present study, we investigated the effects of three different diets containing maggot protein on the growth and intestinal microflora of Litopenaeus vannamei. The shrimp were fed either a control feed (no fly maggot protein added), FM feed (compound feed with 30% fresh fly maggot protein added), FF feed (fermented fly maggot protein), or HT feed (high-temperature pelleted fly maggot protein) for eight weeks. The results showed that fresh fly maggot protein in the feed was detrimental to shrimp growth, whereas fermented and high-temperature-pelleted fly maggot protein improved shrimp growth and survival. The effects of different fly maggot protein treatments on the intestinal microbiota of L. vannamei also varied. Fermented fly maggot protein feed and high-temperature-pelleted fly maggot protein feed increased the relative abundance of Ruegeria and Pseudomonas, which increased the abundance of beneficial bacteria and thus inhibited the growth of harmful bacteria. In contrast, fresh fly maggot proteins alter the intestinal microbiome, disrupting symbiotic relationships between bacteria, and causing invasion by Vibrio and antibiotic-resistant bacteria. These results suggest that fresh fly maggot proteins affect the composition of intestinal microorganisms, which is detrimental to the intestinal tract of L. vannamei, whereas fermented fly maggot protein feed affected the growth of L. vannamei positively by improving the composition of intestinal microorganisms. [ABSTRACT FROM AUTHOR]

Temperature is one of the most important variables that influence aquatic organisms. This study aimed to test physiological and molecular differences in the thermal tolerance of two morphologically similar Marsupenaeus japonicus. The physiological parameter was the upper thermal limit, tested via the critical thermal maximum, and the molecular parameter was the relative messenger RNA expression of heat shock proteins (HSP40, HSP60, HSP70 and HSP90), quantified via real-time polymerase chain reaction. Oxygen consumption of shrimp was measured with a respirometer. M. japonicus variety II showed a higher critical thermal maxima and survival rate and lower oxygen consumption rate than variety I, suggesting that it had higher thermal tolerance and acclimatory plasticity. M. japonicus variety I showed significantly higher production of HSP70 and HSP90, suggesting that these shrimp may have experienced more thermal damage. By comparing the differences in the stress response between two morphologically similar M. japonicus, this study provides useful information for the aquaculture of M. japonicus. [ABSTRACT FROM AUTHOR]

Palytoxins (PLTXs) are a group of complex and poisonous marine natural products that are toxic to marine life and even human beings. In the present study, the oxidative stress and immune response in the hepatopancreas and gills of Litopenaeus vannamei were assessed for 72 h after injection with PLTX extracts. Chemical and physiological parameters, e.g., the respiratory burst (O 2 −), activities of antioxidant enzymes, oxidative damage to lipids, carbonylation of proteins, and immune gene mRNA expression levels, were analysed. The results showed that the PLTX extract was not fatal to the shrimp but could reduce their mobility. The O 2 − levels in the gills gradually increased after exposure to PLTX extracts and were significantly higher than those in the control from 6 to 72 h. The malondialdehyde content, lipid peroxidation, protein carbonyl levels, and total antioxidant capacity in the gills all peaked at 12 h. At the same time, the gills were loosely connected, there was a clear disintegration of the epithelial tissue, and the stratum corneum disappeared after 12 h. In addition, compared to those in the control group, the PLTX extract treatment increased the O 2 − content, malondialdehyde content, lipid peroxidation, and protein carbonyl levels from 12 to 72 h, 24–48 h, 12–24 h, and 12–72 h after injection in the hepatopancreas of the shrimp, respectively. Both the Crustin and Toll gene expression levels significantly increased in the hepatopancreas compared to those in the control 6–72 h after injection of the toxin. In parallel, the expression levels of the manganese superoxide dismutase gene gradually decreased from 6 to 48 h and returned to normal levels after 72 h. Interestingly, the total antioxidant capacity also significantly increased compared to that in the control from 6 to 72 h. Our results indicate that although PLTX extracts cause lipid peroxidation and carbonylation of proteins in hepatopancreatic cells, leading to their damage, they did not cause a decrease in the total antioxidant capacity of the hepatopancreas. • Palytoxin is a complex poisonous molecule found in the marine environment. • Palytoxin was injected into the Pacific white shrimp Litopenaeus vannamei. • Palytoxin was not lethal but caused shrimp immobility. • Palytoxin increased markers of oxidative damage in the hepatopancreas. • Palytoxin did not cause a decrease in the total antioxidant capacity of the hepatopancreas. [ABSTRACT FROM AUTHOR]

C−N bond formation takes on a critical significance in reactions of organic synthesis, material production and pharmaceutical manufactory. Chan‐Lam has proposed a useful methodology to furnish secondary arylamides under mild conditions. However, when chiral sulfinamides serve as the coupling precursors, the Cu‐catalyzed coupling reaction is found with low efficacy. Complex side‐products are generated under classic conditions. Moreover, it led to the racemization of the coupling product. In this study, an optimized Ni‐catalyzed Chan‐Lam type coupling conditions were proposed, which resulted in clean conversion from chiral sulfinamides and arylboronic acids to offer N‐aryl sulfinamides efficiently and enantioretentively. The trans‐N1,N2‐dimethylcyclohexane‐1,2‐diamine was proven as the most efficient ligand. Under the optimized conditions, a series of chiral N‐aryl sulfinamides was prepared with high chemical yield without racemization. Furthermore, a plausible and novel mechanism was proposed. Interestingly, the method could efficiently furnish a wide variety of C−X bonds by coupling arylboronic acids with different nucleophiles. [ABSTRACT FROM AUTHOR]

Flavobacterium columnare is the causal agent of columnaris disease and has severe impacts on the grass carp, Ctenopharyngodon idellus, aquaculture industry. The genetic characteristics of F. columnare strains isolated from grass carp in China are not clear. Therefore, in this study, we obtained 45 bacterial isolates from grass carp with columnaris disease from 11 provinces of China. The 45 bacterial isolates were identified as F. columnare according to phenotypic traits, biochemical characteristics, and molecular identification with 16S rDNA gene sequencing. Furthermore, based on the analysis of restriction fragment length polymorphism of the 16S rDNA gene (16S-RFLP), 37 isolates belonged to genomovar I, 5 isolates were ascribed to genomovar II, and 3 isolates were identified as genomovar III. Phylogenetic analysis further confirmed the genetic differences between the three genomovar isolates and revealed a closer relationship between genomovar I and II isolates. The colony pseudo-root morphology and the degree of bacterial aggregation of the three genomovar isolates were significantly different when they were cultured under the same conditions. We concluded that there are three genotypes of F. columnare currently identified in grass carp, and genomovar I was the main type. These findings provide a basis for the genetic diversity of F. columnare in grass carp in China. • We conducted a survey of columnaris disease of grass carp in 11 provinces of China. • Forty-five bacterial strains were isolated and identified as Flavobacterium columnare. • Three types of genomovars (I, II, III) were identified from the 45 F. columnare strains. • The colony pseudo-root and bacterial aggregation of the three genomovar strains were different. [ABSTRACT FROM AUTHOR]

Triclocarban (TCC) is a widely used broad-spectrum antimicrobial agent that has become a pollutant threatening the health of aquatic animals. However, the toxic effects of TCC on Penaeus monodon are still lacking. In this study, we exposed P. monodon to 1 μg/L (TCC-1) and 10 μg/L TCC (TCC-10) for 14 days, and the changes of histological morphology, physiological and immune responses in the gills were investigated. The results showed that TCC exposure caused the deformation of the gill vessels and the disordered arrangement of the gill filaments. Oxidative stress biochemical indexes such as H 2 O 2 content, CAT and GPx activity and the relative expression levels of antioxidant-related genes (SOD , GPx and Nrf2) were increased in the TCC-1 and TCC-10 groups; the levels of CAT and HSP70 genes were increased but POD activity was decreased in the TCC-10 group. The relative expression levels of endoplasmic reticulum (ER) stress indexes such as ERP15 and ATF-6 genes were increased in the TCC-10 group, while the level of GRP78 gene was decreased in the TCC-1 and TCC-10 groups. The relative expression levels of apoptosis indexes such as p53 and JNK genes were increased, but CytC and Casp-3 genes were decreased in the TCC-1 and TCC-10 groups. Furthermore, the relative expression levels of detoxification metabolism-related genes (cytP450 and GST) and osmotic regulation-related genes (NKA-α , NKA-β , CA , AQP , CLC and CCP) were increased in the TCC-10 group. The results showed that TCC exposure could affect the physiological homeostasis in the gills of P. monodon , probably via damaging histological morphology, inducing oxidative stress, and disordering ER stress, apoptosis, detoxification and osmotic regulation. • The toxic effect of triclocarban (TCC) on Penaeus monodon was evaluated for the first time. • TCC exposure damaged the normal histological morphology of the gills tissue. • TCC exposure induced the oxidative stress response and affected the antioxidant capacity. • TCC exposure disordered ER stress, apoptosis, detoxification and osmotic regulation homeostasis. [ABSTRACT FROM AUTHOR]

Shrimp production is the second ranked of the most-traded production in these decades and the whiteleg shrimp Litopenaeus vannamei is the sixth most cultured species. Probiotics are alternative strategy for the promotion of growth and prevention of diseases in aquaculture. To confirm the effects of the probiotics on development and microbial community of L. vannamei larvae during different development stages, five kinds of probiotics (108 ~ 109 CFU/g) were added into the rearing environment of shrimp larvae, and the effects of probiotics on bacterial community and water quality, larval growth and immune index were determined from nauplius larval stage to post larval stage. Results suggested that probiotics treated groups showed larger survival rate than the control groups from Z1 stage to P5 stage. Lactobacillus could improve the larvae's survival ability, especially in the larval stages M2, M3, P1, P5 stage. It was confirmed that probiotics could promote the growth and development of shrimp larvae and prevent the incomplete molting in their growing process, particularly for EM-treated group. Results suggested that all the probiotics-treated groups had shown significant decreasing trend in the quantity of vibrios, except for the SA-treated group. And different probiotics could inhibit vibrios during different life periods. Among these probiotics, LA, EM and PB had shown the best effects, including improving survival rate of the larvae, promoting the larval metamorphosis, reducing the quantity of vibrios and NH4-N and NO2-N levels, and increasing bacterial diversity. [ABSTRACT FROM AUTHOR]

The orange-spotted grouper (Epinephelus coioides) is a high economic value aquacultural fish in China, however, it often suffers from the outbreak of parasitic ciliate Cryptocaryon irritans as well as bacterium Vibrio harveyi which bring great loss in grouper farming. In the present study, we established a high dose C. irritans local-infected model which caused the mortality of groupers which showed low vitality and histopathological analysis demonstrated inflammatory response and degeneration in infected skin, gill and liver. In addition, gene expression of inflammatory cytokines was detected to assist the estimate of inflammatory response. Furthermore, we also found that the activity of Na+/K+ ATPase in gill was decreased in groupers infected C. irritans and the concentration of Na+/Cl− in blood were varied. Base on the morbidity symptom occurring in noninfected organs, we hypothesized that the result of morbidity and mortality were due to secondary bacterial infection post parasitism of C. irritans. Moreover, four strains of bacteria were isolated from the infected site skin and liver of local-infected groupers which were identified as V. harveyi in accordance of phenotypic traits, biochemical characterization and molecular analysis of 16S rDNA genes, housekeeping genes (gyrB and cpn60) and species-specific gene Vhhp2. Regression tests of injecting the isolated strain V. harveyi has showed high pathogenicity to groupers. In conclusion, these findings provide the evidence of coinfections with C. irritans and V. harveyi in orange-spotted grouper. • A high dose C. irritans skin local infected model of orange-spotted grouper was established. • C. irritans skin local infected grouper induced acute mortality and obvious inflammatory response. • Secondary infected bacterium Vibrio harveyi post C. irritans infection was isolated and identified. [ABSTRACT FROM AUTHOR]

Summary: The purpose of this study was to evaluate the anaesthesia effects of eugenol and MS‐222 sedatives applied on juvenile Lateolabrax maculatus during simulated transport. In experiment 1, the juveniles were divided into two groups, with seven concentrations tested on each group (eugenol [4, 6, 8, 10, 12, 14 and 16 mg/L] and MS‐222 [20, 30, 40, 50, 60, 70 and 80 mg/L]). Induction and recovery times were recorded. The time for anaesthesia was shortened, and the time for complete recovery was prolonged as the anaesthetic concentration increased. The optimal transport concentration for each anaesthetic tested was 6 mg/L of eugenol and 30 mg/L for MS‐222. In experiment 2, the 5‐hr simulated transport test showed that the survival rate of L. maculatus juveniles with anaesthesia was 100%, and without anaesthesia, survival was 60%. After 24 hr of recovery following transport, the fish showed 100% survival for the group with added anaesthetic and 40% for the group without added anaesthetic. Compared to the non‐anaesthetized groups, the anaesthetized transport groups showed significant increases in the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (p < 0.05). The levels of AST, ALT and alkaline phosphatase (AKP) were significantly higher in the MS‐222 transport group than in the eugenol transport group (p < 0.05). The levels of AKP were significantly higher in the non‐anaesthetized transport group than in the anaesthetized group (p < 0.05). According to the present experiment results, eugenol was an efficient anaesthetic in L. maculatus, and we recommend eugenol instead of MS‐222 as an anaesthetic for the short‐time transport of L. maculatus. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of dietary Spirulina platensis supplementation on growth performance, hematological and serum biochemical parameters, hepatic antioxidant status, immune responses and resistance to the pathogen infection in Coral trout Plectropomus leopardus. The fish were fed for 8-week with diets containing different levels of S. platensis : 0% (C), 2% (SP2), 4% (SP4), 6% (SP6), 8% (SP8) and 10% (SP10) as treatment groups, followed by a Vibrio harveyi infection test for 14 d. The study indicated that dietary supplementation with Spirulina platensis could significantly improve growth performance, and the highest weight gain rate (WGR) and specific growth rate (SGR) were observed in group SP10 ( P  < .05). Red cell count (RBC), white cell count (WBC), hemoglobin (Hb) and total antioxidant capacity (T-AOC) in the S. platensis supplemented groups were significantly higher than those of group C ( P  < .05). However, the levels of cholesterol, triglyceride and malondialdehyde (MDA) contents, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities decreased with the increasing of dietary S. platensis levels. Compared with group C, the lysozyme (LYZ) and respiratory burst activities (RBA), and immunoglobulin (Ig) and complement contents in group SP4, SP6, SP8 and SP10 increased significantly than those of group C respectively ( P  < .05). After challenge with V. harveyi , the survival rate in group SP4, SP6, SP8 and SP10 was significantly higher than that of group C, and the highest survival rate was in group SP10 ( P  < .05). These results indicated that P. leopardus fed a diet supplemented with S. platensis (especially at 10%) could significantly promote its growth performance, improve its hepatic antioxidant status, and enhance its immune ability and resistance to V. harveyi infection. [ABSTRACT FROM AUTHOR]

Teprenone is a terpene ketone in which a (9E,13E)-geranylgernayl group is bonded to one of the alpha-methyls of acetone. It has a role as an anti-ulcer drug, a multiple organ protective agent, and a HSP70 inducer. In this study, we evaluated the protective efficiency of teprenone to the damage of two types of anesthetics, tricaine methanesulfonate (MS-222) and eugenol, in the liver and gills of spotted seabass Lateolabrax maculatus. Fish (mean ± SD, 98.6 ± 7.6 g) were exposed to MS-222 (60 mg/L), eugenol (12 mg/L) and anesthetic-free water (control) after being fed diets containing different levels of teprenone: 0 mg/kg (control), 200 mg/kg, 400 mg/kg, and 800 mg/kg for 3 days. Compared with the control group, dietary teprenone significantly decreased cytochrome C concentration, and cysteine-aspartic proteases-3 and cysteine-aspartic proteases-9 activities in the liver and gills. The activities of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase decreased in the serum. The gills morphology was improved, and the heat shock protein 70 concentration and NA+-K+-ATPase activity were significantly increased in gills with admistration of teprenone in the diet. These results reveal that the admisstraiton of teprenone at 400 mg/kg in the diet for three days could reduce the anesthesic damages in L. maculatus by inducing HSP70 and decreasing apoptosis. • MS-222 and eugenol induced apoptosis in gills and liver. • Teprenone reduced apoptosis by inducing heat shock protein 70. • Teprenone also improved mucosa morphology of gills and maintained normal physiological function. [ABSTRACT FROM AUTHOR]