Search

Imidacloprid enters the water environment through rainfall and causes harm to aquatic crustaceans. However, the potential chronic toxicity mechanism of imidacloprid in crayfish has not been comprehensively studied. In this study, red claw crayfish (Cherax quadricarinatus) were exposed to 11.76, 35.27, or 88.17 μg/L imidacloprid for 30 days, and changes in the physiology and biochemistry, gut microbiota, and transcriptome of C. quadricarinatus and the interaction between imidacloprid, gut microbiota, and genes were studied. Imidacloprid induced oxidative stress and decreased growth performance in crayfish. Imidacloprid exposure caused hepatopancreas damage and decreased serum immune enzyme activity. Hepatopancreatic and plasma acetylcholine decreased significantly in the 88.17 μg/L group. Imidacloprid reduced the diversity of the intestinal flora, increased the abundance of harmful flora, and disrupted the microbiota function. Transcriptomic analysis showed that the number of up-and-down-regulated differentially expressed genes (DEGs) increased significantly with increasing concentrations of imidacloprid. DEG enrichment analyses indicated that imidacloprid inhibits neurotransmitter transduction and immune responses and disrupts energy metabolic processes. Crayfish could alleviate imidacloprid stress by regulating antioxidant and detoxification-related genes. A high correlation was revealed between GST, HSPA1s, and HSP90 and the composition of gut microorganisms in crayfish under imidacloprid stress. This study highlights the negative effects and provides detailed sequencing data from transcriptome and gut microbiota to enhance our understanding of the molecular toxicity of imidacloprid in crustaceans., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Antimicrobial peptides (AMPs), which are widely present in animals and plants, have a broad distribution, strong broad-spectrum antibacterial activity, low likelihood of developing drug resistance, high thermal stability and antiviral properties. The present study investigated the effects of adding AMPs from Hermetia illucens larvae on the growth performance, muscle composition, antioxidant capacity, immune response, gene expression, antibacterial ability and intestinal microbiota of Cherax quadricarinatus (red claw crayfish). Five experimental diets were prepared by adding 50 (M1), 100 (M2), 150 (M3) and 200 (M4) mg/kg of crude AMP extract from H. illucens larvae to the basal diet feed, which was also used as the control (M0). After an eight-week feeding experiment, it was discovered that the addition of 100-150 mg/kg of H. illucens larvae AMPs to the feed significantly improved the weight gain rate and specific growth rate of C. quadricarinatus. Furthermore, the addition of H. illucens larvae AMPs to the feed had no significant effect on the moisture content, crude protein, crude fat and ash content of the C. quadricarinatus muscle. The addition of 100-150 mg/kg of H. illucens larvae AMPs in the feed also increased the antioxidant capacity, nonspecific immune enzyme activity and related gene expression levels in C. quadricarinatus, thereby enhancing their antioxidant capacity and immune function. The H. illucens larvae AMPs improved the structure and composition of the intestinal microbiota of C. quadricarinatus, increasing the microbial community diversity of the crayfish gut. Finally, the addition of 100-150 mg/kg of H. illucens larvae AMPs in the feed enhanced the resistance of C. quadricarinatus against Aeromonas hydrophila, improving the survival rate of the crayfish. Based on the aforementioned findings, it is recommended that H. illucens larvae AMPs be incorporated into the C. quadricarinatus feed at a concentration of 100-150 mg/kg., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study aimed to evaluate the potential benefits of chitosan oligosaccharide (COS) on red claw crayfish (Cherax quadricarinatus) and explore its underlying mechanisms. The crayfish were randomly divided into six groups, and the diets were supplemented with COS at levels of 0 (C0), 0.2 (C1), 0.4 (C2), 0.6 (C3), 0.8 (C4), and 1 (C5) g kg -1 . Treatment with COS significantly improved the growth performance of the crayfish with a higher weight gain rate (WGR) and specific growth rate (SGR) in the C2 group compared to the C0 group. Additionally, the content of crude protein in the crayfish muscles in the C1 group was significantly higher than that of the C0 group. Regarding non-specific immunity, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and alkaline phosphatase (AKP), and the levels of expression of the genes related to immunity (SOD; anti-lipopolysaccharide factor [ALF]; thioredoxin1 [Trx1]; C-type lysozyme, [C-LZM]; and GSH-Px) in the hepatopancreas and hemolymph increased significantly (P < 0.05) after supplementation with 0.4 g kg -1 of COS, while the content of malondialdehyde (MDA) decreased (P < 0.05). The survival rate of C. quadricarinatus increased (P < 0.05) in the C2, C3, C4, and C5 groups after the challenge with Aeromonas hydrophila. This study found that COS has the potential to modulate the composition of the intestinal microbiota and significantly reduce the abundance of species of the phylum Proteobacteria and the genera Aeromonas and Vibrio in the gut of C. quadricarinatus, while the abundance of bacteria in the phylum Firmicutes and the genus Candidatus&#95;Hepatoplasma improved significantly. This study suggests that the inclusion of COS in the diet of C. quadricarinatus can enhance growth, boost immunity, and increase resistance to infection with A. hydrophila, especially when supplemented at 0.4-0.8 g kg -1 ., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Astaxanthin is one of the important immunopotentators in aquaculture. However, little is known about the physiological changes and stress resistance effects of astaxanthin in marine gastropods. In this study, the effects of different astaxanthin concentrations (0, 25, 50, 75, and 100 mg/kg) on the growth, muscle composition, immune function, and resistance to ammonia stress in Babylonia areolata were investigated after three months of rearing. With the increase in astaxanthin content, the weight gain rate (WGR), specific growth rate (SGR), and survival rate (SR) of B. areolata showed an increasing trend. The 75-100 mg/kg group was significantly higher than the control group (0 mg/kg). There was no significant difference in the flesh shell ratio (FSR), viscerosomatic index (VSI), and soft tissue index (STI) of the experimental groups. Astaxanthin (75 mg/kg) significantly increased muscle crude protein content and increased hepatopancreas alkaline phosphatase (AKP), superoxide dismutase (SOD), and catalase (CAT) activity. Astaxanthin (75-100 mg/kg) significantly increased the total antioxidant capacity (T-AOC) and acid phosphatase (ACP) of the hepatopancreas and decreased the malondialdehyde (MDA) content of B. areolata. Astaxanthin significantly induced the expression levels of functional genes, such as SOD, Cu/ZnSOD, ferritin, ACP, and CYC in hepatopancreas and increased the survival rate of B. areolata under ammonia stress. The addition of 75-100 mg/kg astaxanthin to the feed improved the growth performance, muscle composition, immune function, and resistance to ammonia stress of B. areolata., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

4-Nonylphenol (4-NP) is one of the common endocrine-disrupting chemicals (EDCs) in estuaries and coastal zones, which can exert detrimental effects on the physiological function of aquatic organisms. However, the molecular response triggered by 4-NP remains largely unknown in Pacific white shrimp (Litopenaeus vannamei). In this study, transcriptomic analysis was performed to investigate the underlying mechanisms of 4-NP toxicity in the hepatopancreas of L. vannamei. Nine RNA-Seq libraries were generated from L. vannamei at 0 h, 24 h, and 48 h following exposure to 4-NP. Compared with 0 h vs 24 h, 962 up- and 463 down-regulated differentially expressed genes (DEGs) were identified, indicating that many genes in L. vannamei were induced to resist adverse circumstances by 4-NP exposure. In contrast, 902 up- and 1027 down-regulated DEGs were revealed in the comparison of 0 h vs 48 h, demonstrating that prolonged exposure to the stress from 4-NP resulted in more inhibited genes. To validate the accuracy of the transcriptome data, eight DEGs were selected for quantitative real-time polymerase chain reaction (qRT-PCR), which were consistent with the RNA-Seq results. Through KEGG pathway enrichment analysis, three specific pathways related to hormonal effects and endocrine function of L. vannamei were enriched significantly, including tyrosine metabolism, insect hormone biosynthesis, and melanogenesis. After 4-NP stress, genes involved in tyrosine metabolism (Tyr) and melanogenesis pathway (AC, CBP, Wnt, Frizzled, Tcf, and Ras) were induced to promote melanin pigment to help shrimp resist adverse environments. In the insect hormone biosynthesis, ALDH, CYP15A1, CYP15A1/C1, and JHE genes were activated to synthesize juvenile hormone (JH), while Spook, Phm, Sad, and CYP18A1 were induced to generate molting hormone. There is an enhanced interaction between the molting hormone and JH, with JH playing a dominant role and maintaining its "classic status quo action". Our study demonstrated that 4-NP exposure led to impairments of biological functions in L. vannamei hepatopancreas. The genes and pathways identified provide novel insights into the molecular mechanisms underlying 4-NP toxicity effects in prawns and enrich the information on the toxicity mechanism of crustaceans in response to EDCs exposure., Competing Interests: Declaration of competing interest No conflict of interest exists in the submission of this manuscript, and the manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously and is not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Alpinia oxyphylla is a homology of medicine and food. This study aims to investigate the dominant chemical composition and explore the antioxidant properties of the ethanol extract of the leaves and stems of A. oxyphylla (AOE) on juvenile shrimp, Litopenaeus vannamei . An in vitro test showed that AOE and its dominant chemical composition procyanidin B-2 ( 1 ) and epicatechin ( 2 ) presented DPPH and ABTS radical scavenging activities. A shrimp feeding supplement experiment revealed that shrimp growth parameters and muscle composition were improved significantly when fed with a 200 mg/Kg AOE additive. Meanwhile, the activities of antioxidant enzymes (CAT, GSH-Px, SOD, and T-AOC) in serum and the liver and the expression of related genes ( LvMn-SOD , LvCAT , LvproPo , and LvGSH-Px ) were enhanced with various degrees in different AOE additive groups while the content of MDA was significantly decreased. Moreover, the antioxidative effect of AOE additive groups on shrimp was also observed in an acute ammonia nitrogen stress test.

Red claw crayfish (Cherax quadricarinatus) is an important freshwater shrimp species worldwide with enormous economic value. Waterless transportation is an inherent feature of red claw crayfish transportation. However, the high mortality of red claw crayfish is a severe problem in the aquaculture of crayfish after waterless transportation. In this study, we investigated the responses of the hepatopancreas from the red claw crayfish undergoing air exposure stress and normal conditions on transcriptome levels. We used Illumina-based RNA sequencing (RNA-Seq) to perform a transcriptome analysis from the hepatopancreas of red claw crayfish challenged by air exposure. An average of 57,148,800 clean reads per library was obtained, and 33,567 unigenes could be predicted and classified according to their homology with matches in the National Center for Biotechnology Information (NCBI) non-redundant protein sequences (Nr), Gene Ontology (GO), a manually annotated and reviewed protein sequence database (Swiss-Prot), protein families (Pfam), Clusters of Orthologous Groups (COG) of proteins, and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. 690 and 3407 differentially expressed genes (DEGs) were identified between the two stress stages of the red claw crayfish. More DEGs were identified in 12 h, indicating that gene expressions were largely changed at 12 h. Some immune-related pathways and genes were identified according to KEGG and GO enrichment analysis. A total of 12 DEGs involved in immune response and trehalose mechanism were verified by quantitative real-time-polymerase chain reaction (qRT-PCR). The results indicated that the red claw crayfish might counteract the stress of air exposure at the transcriptomic level by increasing expression levels of antioxidant-, immune-, and trehalose metabolism-related genes. These transcriptome results from the hepatopancreas provide significant insights into the influence mechanism of air exposure to the trehalose mechanism and immune response in the red claw crayfish., Competing Interests: Declaration of competing interest No conflict of interest exists in the submission of this manuscript, and the manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study aimed to investigate the effects of Elephantopus scaber extract on the GIFT (genetic improvement of farmed tilapia) strain of Nile tilapia Oreochromis niloticus. A total of 800 tilapia with an initial body weight of 1.34 ± 0.09 g each were randomly divided into five groups. The tilapia in the control group (E0 group) were fed on a basal diet only. Meanwhile, tilapia in the four experimental groups were fed on a basal diet supplemented with 1 g/kg (E1 group), 3 g/kg (E2 group), 5 g/kg (E3 group), and 7 g/kg (E4 group) of E. scaber extract for 10 weeks. Results showed that the survival rate was higher in the experimental groups than in the control group. Compared with the control group, some growth parameters (FW, WGR, SGR, VSI, and HSI) were significantly improved in the E1 group and E2 group. The crude lipid content in the dorsal muscle and liver was lower in the E1 group than in the control group. After E. scaber extract supplementation, activities of immunity-related enzymes (ACP, AKP, T-AOC, SOD, CAT, GSH-Px and LZM) in plasma, liver, spleen and head kidney, and expressions of immunity-related genes (IL-1β, IFN-γ, TNF-α, and CCL-3) in liver, spleen and head kidney showed various degrees of improvement, while MDA content and Hsp70 expression level were decreased. The survival rate of tilapia increased in all the supplementation groups after Streptococcus agalactiae treatment. E. scaber extract addition changed the species composition, abundance, and diversity of intestinal microbiota in tilapia. These results demonstrate that E. scaber extract supplementation in diet can improve the growth, immunity, and disease resistance of GIFT against S. agalactiae. E. scaber extract supplementation can also change intestinal microbiota and reduce crude lipid content in dorsal muscle and liver. The above indicators show that the optimal dose of E. scaber extract for GIFT is 1 g/kg., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study was performed to investigate the effects of dietary trehalose on growth, muscle composition, non-specific immune responses, gene expression and desiccation resistance of juvenile red claw crayfish (Cherax quadricarinatus). A total of 540 (body weight of 0.41 ± 0.05) crayfish were randomly divided into six groups for a feeding experiment. Six diets with trehalose levels at 0 (Diet 1), 1 (Diet 2), 2 (Diet 3), 5 (Diet 4), 10 (Diet 5) and 15 (Diet 6) g kg -1 were prepared to feed juvenile red claw crayfish for 8 weeks. The results showed that the weight gain rate (WGR) and specific growth rate (SGR) of crayfish in Diet 4, Diet 5 and Diet 6 groups were significantly improved compared with the control group (Diet 1). Muscle crude protein contents of crayfish fed Diet 4, Diet 5 and Diet 6 were significantly higher than those of the control group. The activities of superoxide dismutase (SOD) and alkaline phosphatase (AKP) in hepatopancreas and hemolymph of crayfish for Diet 4, Diet 5, and Diet 6 groups were significantly increased while malondialdehyde (MDA) content was significantly reduced when compared with the control. The total antioxidant capacity (T-AOC), catalase (CAT) and glutathione peroxidase (GPx) activities in the hepatopancreas and hemolymph of crayfish fed Diet 5 and Diet 6 were significantly higher than those in the control group. However, acid phosphatase (ACP) activity was not significantly different among all experimental groups. The hepatopancreas and intestine trehalose contents of crayfish showed an upward trend with the increase of dietary trehalose levels. Compared with the control group, supplementation of 5-15 g kg -1 trehalose in the feed up-regulated the expression levels of GPx, C-type lysozyme (C-LZM), antilipolysacchride factor (ALF), facilitated trehalose transporter homolog isoform X2 (Tret1-2) and facilitated trehalose transporter isoform X4 (Tret1-4) mRNA. In addition, supplementation of 5-15 g kg -1 trehalose in the feed could improve the survival rate of red claw crayfish under desiccation stress. These results suggested that supplementation of 5-15 g kg -1 trehalose in feed could significantly improve the growth performance, muscle protein, non-specific immunity and desiccation resistance of juvenile red claw crayfish., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Aeromonas species often cause disease in farmed fish. In the present study, dominant bacteria were isolated from diseased crucian carp ( Carassius auratus gibelio ). Based on this, a bacterial isolate was tentatively named CFJY-623. This isolate was identified as Aeromonas veronii based on analysis of its morphological, physiological, and biochemical features, as well as 16S rRNA and gyrB gene sequences. Six virulence genes related to pathogenicity including aerolysin, cytotonic enterotoxins, elastase, glycerophospholipid: cholesterol acyltransferase, lipase, and serine protease were identified in this A. veronii isolate. The median lethal dosage (LD50) of the CFJY-623 isolate for crucian carp was determined as 1.31 × 10 7 CFU/mL. Artificial experimental infection showed that the CFJY-623 isolate caused considerable histological lesions in the fish, including tissue cell degeneration, necrosis, and inflammatory cell infiltrating. Drug sensitivity testing showed that the isolate was susceptible to aminoglycosides, carbapenemes, and nitrofurans. Exploring its growing features showed that this isolate exhibited a high level of environmental adaptability. These results provided a scientific basis for the identification of A. veronii and treatment for fish infected by this pathogen., (Copyright © 2019 Chen, Sun, Han, Yang, Xian, Lv, Hu and Shi.)

The major histocompatibility complex (MHC) is a highly polymorphic region of the vertebrate genome that plays a critical role in initiating immune responses towards invading pathogens. It is well known that MHC I molecules play a central role in the immune response to viruses. However, rare literatures were reported the role of MHC I in the resistance to intracellular bacteria. Sequences of MHC Iα were identified in multiple teleost species, including Japanese flounder (Paralichthys olivaceus), however, the immunological function of MHC Iα remain largely unknown. In this study, we examined the expression profile and biological activity of an MHC Iα homologue, PoMHC Iα, from P. olivaceus. Structural analysis showed that PoMHC Iα possesses conserved structural characteristics of MHC Iα proteins, including MHC&#95;I domain, IGc1 domain, transmembrane region. Expression of PoMHC Iα was upregulated in a time-dependent manner by extracellular and intracellular bacterial pathogens and viral pathogen infection. Different expression patterns were exhibited in response to the infection of different types of microbial pathogens in different immune tissues. Recombinant PoMHC Iα increased the capability of host cells to defense against intracellular pathogen Edwardsiella tarda infection and enhanced the expression of immune related genes. The knockdown of PoMHC Iα attenuated the ability of cells to eliminate E. tarda, which was sustained by the in vivo results that overexpression of PoMHC Iα promoted the host defense against invading E. tarda. Antigen uptake assay indicated PoMHC Iα participated in cells antigen presentation. Collectively, this study is the first report that MHC Iα plays an important role in immune defense against intracellular bacterial pathogen in teleost. Taken together, these findings add new insights into the biological function of teleost MHC Iα and emphasize the importance of MHC I gene products for the control of E. tarda infection., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The main purpose of this study was to investigate the distribution of acid phosphatase (ACP), alkaline phosphatase (ALP), non-specific esterase (NSE), peroxidase (POD), and mucous cells in the intestine of the koi carp Cyprinus carpio var. koi. ACP activity was located in the striated border, enterocytes, and lamina propria of the anterior and middle intestines. The ACP activity in the anterior intestine was higher than that in the middle and posterior intestines. ALP existed in the striated border of enterocytes and lamina propria, serosa, muscular layer, and the junction between muscular layer and submucosa layer of the intestine. The ALP activity in the anterior intestine was higher than that in the middle and posterior intestines. NSE activity was localized in the cytoplasm of enterocytes in the whole intestine, and the middle intestine showed the lower NSE activity than the anterior and posterior intestines. POD activity was localized in the blood cells of the lamina propria and cytoplasm of enterocytes in all intestinal segments. The POD activity among the anterior, middle, and posterior intestines was non-significantly different. Alcian blue periodic acid-Schiff histochemical results revealed three types of mucous cells in the intestine. The total number of mucous cells and percentage of type I cells among the anterior, middle, and posterior intestines were non-significantly different. The percentage of the type II cells was the highest in the posterior intestine, while the lowest in the anterior intestine. The percentage of the type III cells was the highest in the anterior intestine, while the lowest in the posterior intestine.

Thioredoxins (Trxs) play an important role in defending against oxidative stress and keeping disulfide bonding correct to maintain protein function. Edwardsiella piscicida, a severe fish pathogen, has been shown to encode several thioredoxins including TrxA, TrxC, and TrxH, but their biological roles remain unknown. In this study, we characterized TrxH of E. piscicida (named TrxH Ep ) and examined its expression and function. TrxH Ep is composed of 125 residues and possesses typical thioredoxin H motifs. Expression of trxH Ep was upregulated under conditions of oxidative stress, iron starvation, low pH, and during infection of host cells. trxH Ep expression was also regulated by ferric uptake regulator (Fur), an important global regulatory of E. piscicida. Compared to the wild type TX01, a markerless trxH Ep in-frame mutant strain TX01∆trxH exhibited markedly compromised tolerance of the pathogen to hydrogen peroxide, acid stress, and iron deficiency. Deletion of trxH Ep significantly retarded bacterial biofilm growth and decreased resistance against serum killing. Pathogenicity analysis shows that the inactivation of trxH Ep significantly impaired the ability of E. piscicida to invade host cells, reproduce in macrophages, and infect host tissues. Introduction of a trans-expressed trxH gene restored the lost virulence of TX01∆trxH. There is likely to be a complex relationship of functional complementation or expression regulation between TrxH and another two thioredoxins, TrxA and TrxC, of E. piscicida. This is the first functional report of TrxH in fish pathogens, and the findings suggest that TrxH Ep is essential for coping with adverse circumstances and contributes to host infection of E. piscicida.

Glutaredoxin (Grx) is a class molecule oxidoreductase, which can regulate the redox state of proteins and plays a key role in antioxidant defense. However, the informations of Grx cDNA sequences and their functions are lack in decapod crustacea. In the present study, the cDNA of LvGrx 2 was cloned from the Pacific white shrimp, Litopenaeus vannamei. The open reading frame (ORF) of LvGrx 2 was 360 bp, which encoded a polypeptide of 119 amino acids. The molecular mass of the predicted protein is 12.87 kDa with an estimated pI of 8.22. Sequence alignment showed that the amino acid sequence of LvGrx 2 shares 59%, 59% and 58% identity with that of the coelacanth Latimeria chalumnae, the plateau frog Nanorana parkeri and the half-smooth tongue sole Cynoglossus semilaevis, respectively. Quantitative real-time PCR analysis revealed that LvGrx 2 were detected in a wide range of tissues, with highest expression in gill, hepatopancrea and intestine, and weakest expression in muscle. The expression responses of LvGrx 2 were analyzed in hepatopancrea and gill after ammonia-N stress or lipopolysaccharide (LPS) injection. During ammonia-N exposure, the LvGrx 2 transcriptions in hepatopancrea and gill significantly up-regulated, and the peak value appeared after 12 h and 24 h exposure respectively. After LPS injection, expression levels of LvGrx 2 in hepatopancrea obviously increased in the early and late stages, while LvGrx 2 transcription in gill sharply up-regulated in the middle period. These results suggest that LvGrx 2 may play a vital role in shrimp defense system against environmental stress and pathogen infection. RNA interference experiment was designed to further probe roles of LvGrx 2 during ammonia-N exposure. Ammonia-N induced obvious improvement in expression levels of LvGrx 2, LvGrx 3, GPx, GST and Trx, accompanied by increases of protein carbonyl and malondialdehyde (MDA) contents. However, transcription of GPx and GST were much weaker in LvGrx 2 interfered-shrimp, and oxidative damage in both lipid and protein were more serious. These results further suggest that LvGrx 2 in shrimp participates in oxidative defence and regulation of antioxidant system., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

To better understand gene expression in the intestine after Shewanella algae infection and provide insights into its immune roles in the tongue sole, Cynoglossus semilaevis, sequencing-based high-throughput RNA analysis (RNA-Seq) for the intestines between the control group and 12 h post-injection group was performed. After assembly, there was an average of 23,957,159 raw sequencing reads, and 23,943,491 clean reads were obtained after filtering out low-quality reads. Then, 383 differentially expressed genes (DEGs) in the intestines in response to S. algae infection were identified. Subsequently, gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs were conducted to further explore their functions. Among all of the pathways involved, sixteen pathways were related to the immune system, among which the complement and coagulation cascades pathway was the most prominent for immunity-related DEGs, followed by the leukocyte transendothelial migration pathway. Furthermore, the expression levels of twelve selected DEGs in the immune-related pathways were identified by quantitative real-time polymerase chain reaction, substantiating the reliability and reproducibility of the RNA-Seq results. In summary, this study represents an important genomic resource for understanding the potential immune role of the tongue sole intestine from the perspective of gene expression., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study was aimed at investigating the cellular responses of Penaeus monodon haemocytes to poly I:C stimulation using flow cytometric assay. Total haemocyte count (THC), percentages of different haemocyte subpopulations [hyaline cells (HC), semigranular cells (SGC) and granular cells (GC)], non-specific esterase activity (EA), total reactive oxygen species/reactive nitrogen species (ROS/RNS) production, nitric oxide (NO) production, apoptotic haemocyte ratio and plasmic phenoloxidase (PO) activity were determined in poly I:C-injected shrimp. Results showed that poly I:C at a low dose (5 μg shrimp -1 ) caused obvious increases in THC, GC proportion, ROS/RNS production and NO production, but had no significant effect on EA, apoptosis and PO activity. In the early stage of poly I:C injection at a high dose (20 μg shrimp -1 ), THC and GC proportion improvements could also be observed, suggesting that GC might be induced to release from hemocytopoietic or other tissues to participate in immune response, and this subpopulation might be the main cell type involved in the cellular defence against virus. In the later period, proportions of both GC and SGC reduced paralleled by THC reduction, indicating that depletion of GC and SGC was mainly contributed to the reduced count of circulating haemocyte. Obvious increases in ROS/RNS production and NO production were induced in haemocyte of shrimp under a high dose of poly I:C stimulation, but only slight rise of EA and suppression of PO activity could be observed in poly I:C-stimulated shrimp, suggesting that ROS/RNS-dependent system was vital in the immune defence of shrimp against virus. On the other hand, increase of apoptotic haemocyte ratio and THC reduction were presented after the drastic increases of ROS/RNS and NO productions, implying that the stimulated ROS/RNS might be excess and harmful, and was the major factor for the haemocyte apoptosis and depletion. THC recovered after 48 h injection, while haemocyte apoptosis also returned to the control level, suggesting that apoptosis might be contributed to eliminate damaged, weak or infected haemocytes to renew the circulating haemocytes, and it could be considered as an important defending strategy against virus., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Oxidative burst, release of reactive oxygen species/reactive nitrogen species (ROS/RNS) contributed to microorganisms killing, is a vital immune response of crustacean haemocyte. Three morphologic haemocyte types (hyaline cells, HC; semigranular cells, SGC; granular cells, GC) have been defined in crustaceans, and found to play different roles in immune defense. However, oxidative burst activities of different haemocyte subpopulations in crustaceans are currently not documented. In the present study, we investigated the oxidative burst activities of the three haemocyte types in the freshwater prawn Macrobrachium rosenbergii using the common ROS fluorescent probe dichlorofluorescin-diacetate (DCFH-DA). Nitric oxide (NO) donor sodium nitroprusside (SNP) improved the DCF fluorescence in haemocytes, while NO scavenger C-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and NO-synthase inhibitor N G -monomethyl-l-arginine (L-NMMA) reduced the fluorescence, suggesting that DCF fluorescence intensity could also be modified by intracellular NO level and activity of NO-synthase pathway. ROS/RNS was also produced in the untreated haemocytes. GC contained most non-induced ROS/RNS production, while oxidative activity of HC was rather weak. No significant impact of PMA could be observed on ROS/RNS level in all the three cell types. Both zymosan A (ZA) and lipopolysaccharide (LPS) significantly triggered the production of ROS/RNS in SGC and GC, whereas they had no effect on those of HC, suggesting that SGC and GC were the primary cell types involved in pathogens killing by ROS/RNS pathway. Cytochalasin B (Cyt B) inhibited the ZA-induced ROS/RNS production, but could not change the ROS/RNS level stimulated by LPS. For unstimulated haemocytes, ROS/RNS productions decreased 29.6%, 44.1% and 48.6% in SGC, and decreased 44.5%, 28.4% and 57.3% in GC, in the presence of L-NMMA, Fccp and DPI respectively, whereas apocynin could not modulate DCF fluorescence in both SGC and GC, suggesting that mitochondrial oxidative pathway was relatively more dominant in SGC, and NO-synthase (NOS) pathway appeared more active in GC. For LPS-stimulated haemocytes, oxidative activities decreased 22.9%, 42.9%, 29.6% and 60.0% in SGC, and reduced 40.6%, 25.2%, 26.7% and 70.6% in GC with the presence of L-NMMA, apocynin, Fccp and DPI respectively, suggesting that NADPH-oxidase (NOX) pathway in both SGC and GC was activated by LPS, and it became the predominant oxidative pathway in stimulated SGC, while NOS pathway was the relative main source for ROS/RNS production in stimulated GC., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Different haemocyte types have been reported to play diverse roles in immune defense of shrimp. To investigate the roles of the three haemocyte types [hyaline cells (HC), semigranular cells (SGC) and granular cells (GC)] of shrimp in immune responses against lipopolysaccharide (LPS), percentage, non-specific esterase activity (EA), reactive oxygen species (ROS) production and nitric oxide (NO) production of the three haemocyte subpopulations were analyzed in LPS-injected Penaeus monodon using flow cytometry. Results showed that percentage of HC increased after 3 h injection, and returned to the original level after 48 h. Proportion of SGC and GC reduced after 6-36 h and 3-12 h respectively, and recovered to the initial level after 48 and 24 h respectively. Loss of SGC and GC might be related to degranulation to release proPO system, and degranulation of GC seemed more sensitive to LPS stimulation. EA of both HC and SGC improved after 3-6 h injection, while EA of GC was induced after 3-24 h. No significant effect of LPS injection could be found in ROS production and NO production of HC. Enhanced ROS levels was observed in SGC and GC after 3-24 h and 3-36 h respectively, and NO production of SGC and GC improved after 3-48 h injection. These results demonstrated that SGC and GC possessed strong capabilities for LPS-induced EA, ROS production and NO production, while HC only displayed EA response to LPS, suggesting that GC and SGC play the main role in immune defense of shrimp against Gram-negative bacteria., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Accumulation of nitrite in water is highly toxic to aquatic animals. To understand immune responses in shrimp under such environmental stress, a digital gene expression (DGE) technology was applied to detect the gene expression profile of the Litopenaeus vannamei hemocytes in response to nitrite for 48 h. A total of 1922 differently expressed unigenes were generated. Of these transcripts, 1269 and 653 genes were up- or down-regulated respectively. Functional categorization and pathways of the differentially expressed genes revealed that immune defense, xenobiotics biodegradation and metabolism, amino acid and nucleobase metabolic process, apoptosis were the differentially regulated processes occurring during nitrite stress. We selected 19 differential expression transcripts (DETs) to validate the sequencing results by real time quantitative PCR (qPCR). The Pearson's correlation coefficient (R) of the 19 DETs was 0.843, which confirmed the consistency and accuracy between these two approaches. Subsequently, we screened 10 genes to examine the changes in the time course of gene expression in more detail. The results indicated that expressions of ATP-binding cassette transporter (ABC transporter), caspase10, QM protein, C type lectin 4 (CTL4), protein disulfide isomerase (PDI), serine protease inhibitor 8 (SPI8), transglutaminase (TGase), chitinase1, inhibitors of apoptosis proteins (IAP) and cytochrome P450 enzyme (CYP450) were induced to participate in the anti-stress defense against nitrite. These results will provide a reference for follow-up study of molecular toxicology and valuable gene information for better understanding of immune response in L. vannamei under environmental stress., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study was aimed at investigating the in vivo effects of lipopolysaccharide (LPS) injection on Penaeus monodon haemocytes at a cellular level. Cellular responses of LPS-injected shrimp were analysed using flow cytometry. Results showed that LPS injection caused total haemocyte count (THC) and count of large cells (semigranular and granular cells) decline. In LPS-injected shrimp, percentage of large cells decreased at the initial stage, and returned to the original level later. After LPS infection, non-specific esterase activity, reactive oxygen species (ROS) production and nitric oxide (NO) production in haemocytes were significantly induced, while apoptotic cell ratio of haemocytes increased. PO activity in plasma increased in shrimp received LPS at 2 μg g(-1) after 3-12 h and at 8 μg g(-1) after 3-6 h, and then returned to the initial levels. These results demonstrated that LPS induced immune responses on haemocytes, including production of ROS and NO, and release of esterase and PO. On the other hand, THC reduction might be due to the ROS/NO-induced apoptosis. Haemocyte apoptosis which would eliminate damaged or weak cells and contribute to haemocyte renewal, may be a defending strategie against pathogens., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We investigated the effects of deficient and excess dietary selenium (Se) on growth, blood cells apoptosis and liver heat shock protein 70 (HSP70) expression in juvenile yellow catfish (Pelteobagrus fulvidraco). After 8 weeks, yellow catfish (initial weight: 2.12 ± 0.01 g) fed isonitrogenous and isolipid diets containing <0.05 (deficient dietary Se) or 6.5 (excess dietary Se) mg Se/kg displayed a significantly lower weight gain ratio (WGR) than those fed a diet containing 0.23 (normal dietary Se) mg Se/kg. As dietary Se levels increased, liver Se concentration, glutathione peroxidase activity and the hepatosomatic index increased significantly. Plasma glucose concentration was highest in the normal treatment compared with the excess dietary Se treatment. Both deficient and excess dietary Se lead to increased reactive oxygen species (ROS) production and apoptosis ratio in blood cells, whereas only excess dietary Se increased their cytoplasmic free-Ca(2+) (CF-Ca(2+)) concentration. Excess dietary Se also resulted in the highest level of HSP70 expression, thereby possibly providing a protective mechanism against oxidative stress. These results indicate that both deficient and excess dietary Se restrained the growth of juvenile yellow catfish and caused oxidative stress. The overproduction of ROS may act as a signal molecule mediate apoptosis when dietary Se deficiency. Both ROS and CF-Ca(2+) were recorded when dietary Se excess, suggesting that Ca(2+) may be activated by Se and play a major role during Se-induced oxidative stress and cell apoptosis.

This study evaluated the expression level of antioxidant enzymes Cu, Zn-superoxide dismutase (Cu, Zn-SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) in hemocytes of Macrobrachium rosenbergii exposed to copper by real-time PCR (qRT-PCR). Results showed that the mRNA expression of Cu, Zn-SOD increased to reach a peak at 6 h, then recovered to its normal level at 48 h. CAT expression level was significantly increased at 12 h and reached a peak at 24 h, but recovered to its normal level later. GPx expression level was significantly increased at 6 h and reached the peak at 12 h. GST expression level was significantly induced from 12 to 24 h and then dropped to its normal level at 48 h. These results indicated that antioxidant enzymes were inducible, possibly for removing excessive reactive oxygen species to protect prawn from oxidative stress.

Phytases hydrolyze phytate to release inorganic phosphate, which decreases the requirement for phosphorus in fertilizers for crops and thus reduces environmental pollutants. This study analyzed microbial communities in rhizosphere sediment, collected in September 2012 from Shenzhen Bay, Guangdong, China, using high-throughput pyrosequencing; the results showed that the dominant taxonomic phyla were Chloroflexi, Firmicutes, and Proteobacteria, and the proportion of the beneficial bacteria, Bacillus, was 4.95 %. Twenty-nine culturable, phytase-producing bacteria were isolated, their phosphorus solubilization capacity was analyzed, and they were taxonomically characterized. Their phylogenetic placement was determined using 16S ribosomal RNA (rRNA) gene sequence analysis. The result shows that most of the isolates are members of the order Bacillales, although seven strains of Enterobacteriales, two strains of Pseudomonadales, and one strain of Oceanospirillales were also identified. The phytase gene was cloned from SPC09, Bacillus cereus, which showed the highest phosphorus solubilizing ability among the isolated strains. The gene encoded a primary translation product of 335 amino acids. A construct including the 1005-nt ORF fragment, Bc-phy, was transformed into Escherichia coli. The recombinant phytase was produced and purified, which revealed the temperature optima at 60 °C and pH optima at 6.5. The assessment by quantitative PCR (qPCR) showed an abundance of bacteria containing the Bc-phy gene; the level was generally higher in the mangrove forest than in the tidal flats and in surface soil compared to bottom soil, and the highest value was obtained in June. Herein, we report on the cloning, characterization, and activity of a novel phytase isolated from a mangrove system.

This study investigated the effect of ambient Cadmium (Cd) on haemocyte apoptosis of the shrimp, Penaeus monodon. Cellular response was determined in Cd-exposed (0, 0.05, 0.5 and 5 mg L(-1)) shrimp. Results showed that 0.05 mg L(-1) Cd(2+) had no significant effect on the haemocyte parameters during the 48 h exposure. Cadmium at doses of 0.5 and 5 mg L(-1) depressed the total haemocyte count (THC), and increased reactive oxygen species (ROS) production and apoptosis ratio in haemocytes. Esterase activity increased in shrimp exposed to 0.5 mg L(-1) Cd(2+) for 6 h, and decreased to the initial level later. Depressed esterase activity could be observed in shrimp after 24 and 48 h exposure to 5 mg L(-1) Cd(2+). These results demonstrated that Cd(2+) modified esterase activity and induced ROS generation, which led to haemocyte apoptosis and THC reduction. Oxidative stress is one of the induction mechanisms for Cd-caused apoptosis of shrimp haemocytes.

In the present study, transcriptome of nitrite-exposed Litopenaeus vannamei was performed using a newly developed high-throughput sequencing technology (Illumina RNA-seq). As many as 42,336 unigenes were generated with 561 bp of average length and 736 bp of unigene N50 after filtering and assembly. These unigenes from the de novo assembly were further annotated using BLAST and BLAST2GO softwares. A total of 23,532 unigenes were unambiguous alignments to the reference when BLAST against non-redundant protein sequence (Nr), non-redundant nucleotide (Nt), Swiss-Prot, Gene Ontology database (GO), Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases available at NCBI. Numerous candidate genes associated with immune response, detoxification, apoptosis pathway were identified. Ten candidate genes related to immune responses and apoptosis were selected for validating the results of assembly and annotation by real-time quantitative PCR. Results revealed that the expressions of all these ten genes were up-regulated after nitrite exposure. Combining to our previous study, we speculate that all these selected genes may be involved in the response to nitrite stress. The study shows a systematic overview of the transcriptome analysis in L. vannamei, and provides valuable gene information for studying molecular mechanisms under nitrite exposure., (Copyright © 2013. Published by Elsevier Ltd.)

A flow cytometric method to measure the production of intracellular nitric oxide (NO) was adapted for use with shrimp haemocytes. We applied fluorescent probe 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA) for NO detection in haemocytes from the tiger shrimp Penaeus monodon, and used flow cytometry to quantify fluorescence intensity in individual haemocyte. The optimized protocol for intracellular NO analysis consists to incubate haemocytes with DAF-FM DA at 10 μM for 60 min to determine the mean fluorescence intensity. Result showed that NO was also produced in the untreated shrimp haemocytes. NO level in granular cells and semigranular cells were much higher than that in hyaline cells. Defined by different characteristic of NO content, three subsets of haemocytes were observed. Zymosan A at dose of 10 or 100 particles per haemocyte triggered higher DAF-FM fluorescence intensity in granular and semigranular cells, than PMA that had no significant impact on all three cell types. These results indicate that granular and semigranular cells are the primary cells for NO generation. Cytochalasin B significantly inhibited the NO level induced by zymosan A. NG-Monomethyl-L-arginine (L-NMMA) and diphenylene iodonium chloride (DPI) significantly suppressed the DAF-FM fluorescence in haemocytes, but apocynin could not modulate it, indicating that the DAF-FM fluorescence was closely related to the activity of NO-synthase pathway. The NO donor sodium nitroprusside (SNP) improved the DAF-FM fluorescence in haemocytes, while the NO scavenger C-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) significantly decreased the fluorescence, demonstrating that the fluorescence intensity of DAF-FM is mainly dependent on the intracellular NO level.

Five feeding trials based on the isonitrogenous and isoenergetic experimental diets containing 34% protein, 6%, 8%, 10%, 12% or 14% lipid respectively in the circulating water culture system for both 30 and 60 days were conducted to investigate the effect of the dietary lipid level on the growth and immunity in white shirmp, Litopenaeus vannamei adults. The body weight and specific growth rate of white shrimp in different treatments indicated that shrimps fed the diet of 12% lipid level for 30d and 10% lipid level for 60d had the best developmental status. The ability of respiratory burst in hemocytes was improved as the increase of dietary lipid level. The transcripts of LGBP and pPO were sensitive to the dietary lipid in hemocyte and hepatopancreas respectively. The activities of CAT, GPx and AKP were increased to a certain extend according to dietary lipid level. Qualification of MDA showed the lowest level in the sample subjected to 12% lipid level diet, indicating an optimal utilization of the dietary lipid and an efficient clearance of MDA in vivo. These results suggested that dietary lipid level of 10-12% significantly tunes the growth and enhance the immune abilities mainly via ROS pathway of L. vannamei., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Apoptotic cell ratio and mRNA expression of caspase-3, cathepsin B (CTSB), heat shock protein 70 (HSP70), manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPx) and thioredoxin (TRx) in hemocytes of white shrimp Litopenaeus vannamei exposed to nitrite-N (20 mg/L) was investigated at different stress time (0, 4, 8, 12, 24, 48 and 72 h). The apoptotic cell ratio and mRNA expression level of CTSB were significantly increased in shrimp exposed to nitrite-N for 48 and 72 h. Caspase-3 mRNA expression level significantly increased by 766.50% and 1811.16% for 24 and 48 h exposure, respectively. HSP70 expression level significantly increased at 8 and 72 h exposure. MnSOD mRNA expression in hemocytes up-regulated at 8 and 48 h, while CAT mRNA expression level increased at 24 and 48 h. GPx expression showed a trend that increased first and then decreased. Significant increases of GPx expression were observed at 8 and 12 h exposure. Expression level of TRx reached its highest level after 48 h exposure. These results suggest that nitrite exposure induces expression of apoptosis-related genes in hemocytes, and subsequently caused hemocyte apoptosis. Meanwhile, expression levels of HSP70 and antioxidant enzymes up-regulated to protect the hemocyte against nitrite stress., (Copyright © 2013 Elsevier Inc. All rights reserved.)

This study was aimed at investigating the toxicity mechanism of lipopolysaccharide (LPS) on Penaeus monodon haemocytes at a cellular level. Reactive oxygen species (ROS) production, nitric oxide (NO) production, non-specific esterase activity, cytoplasmic free-Ca(2+) (CF-Ca(2+)) concentration, DNA damaged cell ratio and apoptotic cell ratio of in vitro LPS-treated haemocytes were measured by flow cytometry. Two concentrations of Escherichia coli LPS (5 and 10 μg mL(-1)) were used. Results showed that ROS production, NO production and CF-Ca(2+) concentration were significantly induced in the LPS-treated haemocytes. Ratio of DNA damaged cell and apoptotic cell increased caused by LPS, while esterase activity increased at the initial 60 min and dropped later. The initial increase in esterase activity suggested that LPS activated the release of esterase, and the later decrease might result from apoptosis. These results indicated that LPS would induce oxidative stress on shrimp haemocytes, and cause Ca(2+) release, DNA damage and subsequently cell apoptosis. This process of ROS/RNS-induced Ca(2+)-mediated apoptosis might be one of the toxicity mechanisms of LPS on shrimp haemocytes., (Copyright © 2012 Elsevier Inc. All rights reserved.)

This study investigated the toxic effects of cadmium on viability, reactive oxygen species (ROS) production and non-specific esterase activity of Penaeus monodon haemocytes in vitro, using a flow cytometric assay. After 6 h in vitro exposure with 10(-9)-10(-3) M Cd(2+), cell viability, ROS production and esterase activity of haemocytes from P. monodon were determined. Results showed that at the lowest exposures (10(-9)-10(-6 )M), Cd(2+) induced no effect on cell viability, ROS production and esterase activity. At a higher level (10(-5) M) of exposure, production of ROS was stimulated while Cd(2+) had no effect on cell viability and esterase activity. At the two highest concentrations (10(-4) and 10(-3) M), Cd(2+) caused increased ROS production, cell death and inhibited esterase activity. These results showed a relationship between Cd(2+) exposure dose and its cytotoxicity on shrimp haemocytes. Cadmium was cytotoxic and immunotoxic for P. monodon haemocytes in vitro when the dose reached 10(-4) M. The study also suggested that flow cytometry could be used as a tool for cytotoxic research of aquatic contamination on shrimp.

This study investigated the in vitro effects of nitrite on reactive oxygen species (ROS) production, NO production, esterase activity and cell apoptosis of Penaeus monodon haemocytes. Haemocytes were in vitro exposed to different dose of nitrite (0, 0.1, 0.5, 1, 5 and 10 μM). Cellular responses of nitrite-treated haemocytes were determined by flow cytometry. The results revealed that haemocytes treated by nitrite in vitro showed conspicuous time- and dose-dependent decreases in ROS and NO production as well as esterase activity. Additionally, 0.1 and 0.5 μM nitrite did not affect the apoptotic cell ratio during the 3h experimental time, while significant increases in apoptotic cells were observed after haemocyte exposure to nitrite at 1 μM for 3h, and at 5 or 10 μM for 1h. These results indicated that nitrite suppresses cellular functions, including production of ROS and NO, and activity of esterase. Cell apoptosis of haemocytes would be induced by extracellular nitrite as doses exceed 1 μM., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The aim of this study was to investigate the cellular toxicity of copper-induced injury to the black tiger shrimp Penaeus monodon. The 24h, 48h, 72h and 96h LC(50) (median lethal concentration) of Cu(2+) on P. monodon (11.63+/-1.14g) were found to be 3.49, 1.54, 0.73 and 0.40mgL(-1), respectively. Total haemocyte count (THC), phagocytic activity, respiratory burst (RB), cytoplasmic free-Ca(2+) (cf-Ca(2+)) concentration and apoptotic cell ratio of shrimp were determined after exposure to different concentrations of Cu(2+) (0, 0.05, 0.5, 1.5 and 3.5mgL(-1)) for 0, 6, 12, 24 and 48h. There was no significant effect on the analytic indicator of shrimp exposed to 0.05mgL(-1) Cu(2+). THC decreased after Cu-exposure to 0.5mgL(-1) for 48h, 1.5mgL(-1) for 24h and 3.5mgL(-1) for 12h. Phagocytic activity decreased in P. monodon following 48h exposure to 3.5mgL(-1) Cu(2+). RB was induced after 6h exposure to 0.5, 1.5 and 3.5mgL(-1) Cu(2+). cf-Ca(2+) concentration increased after 48h exposure to 0.5mgL(-1) Cu(2+), and 12h exposure to 1.5 and 3.5mgL(-1) Cu(2+). The percentage of apoptotic cells increased to 9.5%, 16.3% and 18.6% respectively following 48h exposure to 0.5, 1.5 and 3.5mgL(-1) Cu(2+). These results indicate that Cu can induce oxidative stress, elevation of cf-Ca(2+) and cell apoptosis, and inhibit phagocytic activity in the shrimp P. monodon, and the lethal injury of Cu(2+) to P. monodon may be mainly due to the sharp reduction of THC caused by ROS-induced apoptosis., (Copyright 2010 Elsevier Inc. All rights reserved.)