Exopalaemon Carinicauda Research Articles

Toxicity assessment and detoxification metabolism of sodium pentachlorophenol (PCP-Na) on marine economic species: a case study of Moerella iridescens and Exopalaemon carinicauda.

Sodium pentachlorophenol (PCP-Na) is widespread in the marine environment; however, its impact on marine organisms remains under-researched. Moerella iridescens and Exopalaemon carinicauda are marine species of economic importance in China and under threat from PCP-Na pollution. Thus, this study aimed to assess the toxicity and detoxification metabolism of PCP-Na on M. iridescens and E. carinicauda. The study revealed that the 96h median lethal concentration (LC50) of PCP-Na for M. iridescens and E. carinicauda were 9.895mg/L and 14.143mg/L, respectively. A species sensitivity distribution (SSD) for PCP-Na was developed specifically for marine organisms, determining a hazardous concentration to 5% of the species (HC5) of 0.047mg/L. During the sub-chronic exposure period, PCP-Na accumulated significantly in M. iridescens and E. carinicauda, with highest concentrations of 41.22mg/kg in the soft tissues of M. iridescens, 42.58mg/kg in the hepatopancreas of E. carinicauda, and only 0.85mg/kg in the muscle of E. carinicauda. Furthermore, the study demonstrated that detoxifying metabolic enzymes and antioxidant defense system enzymes of E. carinicauda responded stronger to PCP-Na compared to M. iridescens, suggesting that E. carinicauda may possess a stronger detoxification capacity. Notably, five biomarkers were identified and proposed for monitoring and evaluating PCP-Na contamination. Overall, the results indicated that M. iridescens and E. carinicauda exhibit greater tolerance to PCP-Na than other marine species, but they are susceptible to accumulating PCP-Na in their tissues, posing a significant health risk. Consequently, conducting aquatic health risk assessments in areas with potential PCP-Na contamination is strongly recommended.

Functional analysis of the cell cycle protein E gene (ccne) in ovarian development of the white ridgetail prawn, Exopalaemon carinicauda

To investigate the function of the cell cycle Cyclin E gene (ccne) in the ovarian development of Exopalaemon carinicauda, the gene was cloned using the RACE technique, and the relative expression of ccne was analyzed in different tissues at different stages of ovarian development. The effect of knocking down the expression of ccne on yolk protein vitellogenin (vg) was also investigated at ovarian developmental stage II using RNAi. The results showed that the full-length cDNA sequence of ccne in E. carinicauda (1692 bp, with a 5′UTR of 127 bp, a 3′UTR of 299 bp, and an ORF of 1266 bp) could encode a total of 421 amino acids, with a predicted protein molecular weight of 48.04 kDa and a theoretical isoelectric point of 6.28. The relative expression of ccne was high during all stages of ovarian development, with the highest expression occurring in stage III. In addition, the phylogenetic tree showed that E. carinicauda and Penaeus monodon were clustered into one branch. Knocking down the ccne expression inhibited the expression of vg, meaning that the expression of ccne and vg were positively correlated. In situ hybridization showed that ccne was abundantly expressed in ova, thus inferring that ccne plays a regulatory role and is involved in nutrient accumulation and transport in the ovaries of E. carinicauda.

Characterization of a crustin-like peptide involved in shrimp immune response to bacteria and Enterocytozoon hepatopenaei (EHP) infection in Palaemon carinicauda.

Crustins represent one type of antimicrobial peptides (AMPs) that are key components of the innate immune process of crustaceans. This study successfully identified a novel crustin-like peptide, EcCrustin2, in ridgetail white prawn, Palaemon carinicauda (formerly Exopalaemon carinicauda). EcCrustin2 was found to be 1082 bp in length, with a 378 bp open reading frame (ORF) encoding 125 amino acids. The deduced amino acid sequence of EcCrustin2 exhibited characteristics of crustins in crustacean, including a Cys-rich region at the N-terminus as well as a whey acidic protein domain at the C-terminus. Phylogenetic analysis revealed that the EcCrustin2 was first clustered with Type I crustins, then with other crustins. Expression of EcCrustin2 was mainly detected in immune tissues, including hemocytes, gill and stomach. The expression level of EcCrustin2 was also significantly up-regulated after being exposed to lipopolysaccharide (LPS), lipoteichoic acid (LTA), Vibrio parahaemolyticus and Staphylococcus aureus. EHP infection could also induce EcCrustin2 expression in P. carinicauda. Knockdown of EcCrustin2 with siRNA increased the mortality of V. parahaemolyticus challenged shrimp. Finally, the recombinant EcCrustin2 protein was obtained and demonstrated a wide spectrum of antibacterial activity in vitro. These results indicated that EcCrustin2 takes part in the immune response against bacteria and EHP infection.

Molecular characterization and developmental function of jagged-1 in Exopalaemon carinicauda (Decapoda, Caridea, Palaemonidae)

Abstract The Notch signalling pathway is widely present in organisms and is an essential factor involved in the developmental process. JAGGED-1, as an important ligand in the Notch signalling pathway, has been cloned from Exopalaemon carinicauda and its role in growth and development have been studied. The full length of the jagged-1 cDNA of E. carinicauda was 5148 bp encoding a protein composed of 1307 amino acids, which had the highest identity with JAGGED-1 of Procambarus clarkii. The expression of jagged-1 varied with development, with the highest expression at the gastrula stage of embryonic development, the Z2 stage of larval development, and the G4 stage of ovary development, respectively. The expression of jagged-1 in the interference group was significantly lower than that in the control group between 3 and 72 h post jagged-1 RNA interference. The expression of key genes in the Notch signalling pathway, including notch1 and delta, and genes related to growth and development, including chh, gih and mih, decreased significantly post jagged-1 RNA interference. After continuous jagged-1 RNA interference, the ovary of the interference group only developed to the G3 stage, while the ovary of the control group developed to the G4 stage. Further study found that there were 8 SNPs including one missense mutation (SNP 2389 T > C) and seven synonymous mutations, and the SNP 2389 T > C and SNP 2799 G > C might be related to the growth of E. carinicauda. The results showed that jagged-1 was involved in the growth and development of E. carinicauda.

Microalgae-mediated tandem culture of shrimp and bivalve: an environmental and health co-benefits solution for phosphorus recovery and emission reduction

Phosphorus (P) accumulation in aquaculture systems is damaging our environment beyond acceptable levels. Devising strategies to potentially recover P from aquaculture systems in a reusable bioresource form is paramount and aligns with circular economy policies. In this study, we constructed two culture models, monoculture (Mon) and tandem culture (Tan), using Exopalaemon carinicauda and Mercenaria mercenaria. By monitoring the performance of rearing organisms, P dynamic patterns, and pollutant emissions, we found that: i) Compared to the Mon system, the Tan system demonstrated no differences in the performance of E. carinicauda and M. mercenaria, suggesting that the Tan model was viable in terms of fishery yield; ii) P in the Tan system could be efficiently recovered and removed from water and sediment, as indicated by the lower phosphate concentration in water (0.01 mg L−1), and the decrease in labile P in surface sediment (from 0.04 to 0.02 mg L−1). A combination of assimilatory and dissimilatory processes, mediated by phototrophic (bait-microalgae) and heterotrophic organisms (bivalves), appeared to be the primary mechanism for P utilization and removal; iii) The Tan system reduced pollutant emissions four times lower than the Mon system due to its minimal tailwater discharge (10%, 230 L). The emissions of total P, phosphate, total organic carbon, ammonium, and chemical oxygen demand from the Tan systems were 19 mg m−2 d−1, 2 mg m−2 d−1, 2 g m−2 d−1, 38 mg m−2 d−1, and 11 g m−2 d−1, respectively, 1.3, 1.7, 1.4, 1.3, and 1.2 times lower than those from the Mon systems. The eco-friendly Tan culture model fully exploited the resources of pond culture, a solution with environmental and health co-benefits for P recovery and emission reduction.

Changes of visual appeal and bioactive nutritional profiles of the astaxanthin-accumulated new variety and wild-type prawn in Exopalaemon carinicauda submitted to different domestic cooking processes

Changes of visual appeal and bioactive nutritional profiles of the astaxanthin-accumulated new variety and wild-type prawn in Exopalaemon carinicauda submitted to different domestic cooking processes

Effects of salinity on growth and related indicators of gonadal development in Exopalaemon carinicauda (Decapoda, Caridea, Palaemonidae)

Abstract To explore the effects of salinity on the growth and gonadal development of Exopalaemon carinicauda, shrimps were raised at five different levels of salinity (16, 20, 24, 28, 32) in a water environment. The growth, performance in ovarian development, ovarian nutrient concentration, as well as vitellogenin and sex hormone levels were measured. The results showed that the final body weight and specific growth rate of E. carinicauda increased at first and then decreased with increasing salinity (), with the fastest growth occurring at salinity 24. The gonadosomatic index increased at first and then decreased with increasing salinity (), with the highest index also occurring at salinity 24. The ovarian maturation rate of E. carinicauda was highest at salinity 28, and the concentration of total protein, total cholesterol, and triglycerides in the ovaries similarly increased at first until salinity 24, and then decreased with increasing salinity (). Likewise, the concentration of vitellogenin in the hepatopancreas increased at first and then decreased with increasing salinity (), with the highest concentration occurring at salinity 24. The concentration of estradiol in E. carinicauda ovaries was highest in the groups at salinities 24 and 28. These results show that salinity levels of 24-28 were the most suitable for promoting the maturation of parent shrimps, and thus would likely be optimal for industrial culturing.

Profiles of cyclin B and cdc2 during ovarian and embryonic development in Exopalaemon carinicauda

Mitosis-promoting factor (MPF) is a complex formed by cyclin B (cyclin B) and cyclin-dependent kinase (cdc2). To investigate the role of MPF in the reproduction of Exopalaemon carinicauda, we cloned its full-length cDNA of the Ec-cyclin B and Ec-cdc2 genes. We analyzed their molecular characteristics and expression profiles during ovarian and embryonic development. The results showed that the Ec-cyclin B gene was 1194 bp long and encoded a 397 amino acid (aa) long protein. However, Ec-cdc2 was 900 bp long, which encoded 299 aa with a conserved cyclin binding motif PSTAIRE. The phylogenetic tree analysis showed that Ec-cyclin B had the highest homology with the cyclin B of Macrobrachium rosenbergii (81.06%). In comparison, Ec-cdc2 had the highest homology with the cdc2 of E. modestus (96.80%). Ec-cyclin B showed the highest expression in the ovary, whereas Ec-cdc2 was the highest in the hepatopancreas, followed by the ovary. In the five stages of ovarian development, Ec-cyclin B and Ec-cdc2 expression levels reach the highest at stage Ⅴ(p < 0.05). Overall, the expression of these two genes first increased and then decreased at different embryonic developmental stages. Therefore, these findings suggested that cyclin B and cdc2 played an essential role in the ovarian and embryonic development of E. carinicauda.

Comparative transcriptome and gut microbiota analysis of Exopalaemon carinicauda with different growth rates from a full-sib family

In the breeding process of Exopalaemon carinicauda from the same family, noticeable differences often occur in growth characteristics under the same conditions. To investigate this issue, we performed a comparative transcriptome analysis to identify the critical genes involved in weight gain and compared the intestinal flora to screen for potential intestinal probiotics. In total, we identified 1311 differentially expressed genes (DEGs), of which 735 genes, including troponin C, chitinase, cathepsin B, cathepsin L, and trypsin, were upregulated exclusively in the fast growth group. Several DEGs were validated by quantitative real-time PCR and assigned to the ribosome, phagosome, apoptosis, purine metabolism, and Hippo signaling pathways. The microbiome community richness and diversity of the fast-growing individuals (FGIs) were higher than those of the slow-growing individuals (SGIs). In the current study, the intestinal microflora was mainly distributed in the Proteobacteria, Firmicutes, and Bacteroidota. The species with significant differences (P < 0.05) between the FGI and SGI groups included the iron-reducing bacteria, Nitrospira moscoviensis, Sulfuritalea hydrogenivorans, and Alpha proteobacterium. Our results provided insights towards revealing the mechanism underlying the growth differences in E. carinicauda.

Complete genome analysis of pathogenic Metschnikowia bicuspidata strain MQ2101 isolated from diseased ridgetail white prawn, Exopalaemon carinicauda

BackgroundMetschnikowia bicuspidata is a pathogenic yesst that can cause disease in many different economic aquatic animal species. In recent years, there was a new disease outbreak in ridgetail white prawn (Exopalaemon carinicauda) in coastal areas of Jiangsu Province China that was referred to as zombie disease by local farmers. The pathogen was first isolated and identified as M. bicuspidata. Although the pathogenicity and pathogenesis of this pathogen in other animals have been reported in some previous studies, research on its molecular mechanisms is still very limited. Therefore, a genome-wide study is necessary to better understand the physiological and pathogenic mechanisms of M. bicuspidata.ResultIn this study, we obtained a pathogenic strain, MQ2101, of M. bicuspidata from diseased E. carinicauda and sequenced its whole genome. The size of the whole genome was 15.98 Mb, and it was assembled into 5 scaffolds. The genome contained 3934 coding genes, among which 3899 genes with biological functions were annotated in multiple underlying databases. In KOG database, 2627 genes were annotated, which were categorized into 25 classes including general function prediction only, posttranslational modification, protein turnover, chaperones, and signal transduction mechanisms. In KEGG database, 2493 genes were annotated, which were categorized into five classes, including cellular processes, environmental information processing, genetic information processing, metabolism and organismal systems. In GO database, 2893 genes were annotated, which were mainly classified in cell, cell part, cellular processes and metabolic processes. There were 1055 genes annotated in the PHI database, accounting for 26.81% of the total genome, among which 5 genes were directly related to pathogenicity (identity ≥ 50%), including hsp90, PacC, and PHO84. There were also some genes related to the activity of the yeast itself that could be targeted by antiyeast drugs. Analysis based on the DFVF database showed that strain MQ2101 contained 235 potential virulence genes. BLAST searches in the CAZy database showed that strain MQ2101 may have a more complex carbohydrate metabolism system than other yeasts of the same family. In addition, two gene clusters and 168 putative secretory proteins were predicted in strain MQ2101, and functional analysis showed that some of the secretory proteins may be directly involved in the pathogenesis of the strain. Gene family analysis with five other yeasts revealed that strain MQ2101 has 245 unique gene families, including 274 genes involved in pathogenicity that could serve as potential targets.ConclusionGenome-wide analysis elucidated the pathogenicity-associated genes of M. bicuspidate while also revealing a complex metabolic mechanism and providing putative targets of action for the development of antiyeast drugs for this pathogen. The obtained whole-genome sequencing data provide an important theoretical basis for transcriptomic, proteomic and metabolic studies of M. bicuspidata and lay a foundation for defining its specific mechanism of host infestation.

Distribution of microplastics in different tissues of major commercial catches in different functional areas of the South Yellow Sea

The microplastic (MP) pollution in different tissues of six commercial catches, including (Miichthys miiuy, Eleutheronema tetradactylum, Collichthys lucidus, Mugil cephalus, Portunus trituberculatus and Exopalaemon carinicauda) in Haizhou Bay (nori farming area), Yancheng offshore (wind power construction area) and the Nantong marine ranch area of the South Yellow Sea was investigated. MPs are ubiquitous in commercial catches; the average abundance of MPs is 5.19 ± 3.64 items/individual. There are significant differences in the level of MP pollution in commercial catches among functional sea areas. The level of MP pollution in commercial catches in Haizhou Bay and Yancheng offshore is higher than that in the Nantong marine ranch areas. This difference may be related to intense anthropogenic activities such as engineering construction and mariculture. In addition to the presence in digestive tract, MPs in the skin and gills of fish and in the gills of shrimp and crabs cannot be ignored. The main shape, color and material of MPs are fiber, black-gray and celluloid (CP), respectively. Since commercial catches are consumed by humans, the potential risks of MPs in these catches to human health and marine ecology are of concern.

Molecular Characterization Related to Ovary Early Development Mechanisms after Eyestalk Ablation in Exopalaemon carinicauda.

Eyestalk ablation is an effective method to promote ovarian development in crustaceans. Herein, we performed transcriptome sequencing of ovary and hepatopancreas tissues after eyestalk ablation in Exopalaemon carinicauda to identify genes related to ovarian development. Our analyses led to the identification of 97,383 unigenes and 190,757 transcripts, with an average N50 length of 1757 bp. In the ovary, four pathways related to oogenesis and three related to oocyte rapid growth were enriched. In the hepatopancreas, two vitellogenesis-associated transcripts were identified. Furthermore, short time-series expression miner (STEM) and gene ontology (GO) enrichment analyses revealed five terms related to gamete generation. In addition, two-color fluorescent in situ hybridization results suggested that dmrt1 might play a vital role in oogenesis during the early stage of ovarian development. Overall, our insights should support future studies focusing on investigating oogenesis and ovarian development in E. carinicauda.

Effect of high alkalinity on shrimp gills: Histopathological alternations and cell specific responses

High alkalinity stress was considered as a major risk factor for aquatic animals surviving in saline-alkaline water. However, few information exists on the effects of alkalinity stress in crustacean species. As the dominant role of gills in osmotic and ionic regulation, the present study firstly evaluated the effect of alkalinity stress in Exopalaemon carinicauda to determine changes in gill microstructure, and then explore the heterogeneity response of gill cells in alkalinity adaptation by single-cell RNA sequencing (scRNA-seq). Hemolymph osmolality and pH were increased remarkably, and gills showed pillar cells with more symmetrical arrangement and longer lateral flanges and nephrocytes with larger vacuoles in high alkalinity. ScRNA-seq results showed that alkalinity stress reduced the proportion of pillar cells and increased the proportion of nephrocytes significantly. The differentially expressed genes (DEGs) related to ion transport, especially acid-base regulation, such as V(H+)-ATPases and carbonic anhydrases, were down-regulated in pillar cells and up-regulated in nephrocytes. Furthermore, pseudotime analysis showed that some nephrocytes transformed to perform ion transport function in alkalinity adaption. Notedly, the positive signals of carbonic anhydrase were obviously observed in the nephrocytes after alkalinity stress. These results indicated that the alkalinity stress inhibited the ion transport function of pillar cells, but induced the active role of nephrocytes in alkalinity adaptation. Collectively, our results provided the new insight into the cellular and molecular mechanism behind the adverse effects of saline-alkaline water and the saline-alkaline adaption mechanism in crustaceans.

Proteomic analysis of the hepatopancreas of Exopalaemon carinicauda in response to Metschnikowia bicuspidate infection

The ridge-tail white prawn, Exopalaemon carinicauda, is an important economic shrimp in the mariculture of China, especially in Jiangsu Province. The “zombie disease” of ridge-tail prawn is a new epidemic that is a highly transmissible and pathogenic fungal disease caused by Metschnikowia bicuspidate infection. To understand the response mechanism of E. carinicauda after M. bicuspidate infection, the hepatopancreas of shrimp injected with M. bicuspidate MQ2101 and normal saline solution were used for proteomics analysis. A total of 5078 proteins were identified, of which 1708 proteins were identified as differentially expressed proteins (DEPs, 1311 upregulated and 397 downregulated) using a 1.2-fold change in expression as a physiologically significant benchmark. These DEPs were mainly involved in cellular processes, single-organism processes, and metabolic processes in the GO enrichment analysis and metabolism, translation, signal transduction, cell growth and death, and immune system pathways in the KEGG enrichment analysis. The DEPs related to immunity and metabolism were significantly changed, such as CTSB, CPs, DSP1, GDP, and ADH3, and these proteins might be potential determinants of E. carinicauda responses to M. bicuspidata infection. qRTPCR was used to detect changes in the expression of nine DEP-related genes at the transcriptional level to validate the proteomics analysis results, and the results of the transcription tendencies in qRTPCR were consistent with proteomics analysis. The results of this study might provide an important theoretical basis for the response mechanism of ridge-tail white prawns to M. bicuspidate infection and scientific prevention and control of this fungus in ridge-tail white prawn aquaculture. Availability of data and materialsThe data that support the results of this present study are available from the corresponding author upon reasonable request.

Cloning of notch1 and its role in the growth and development of Exopalaemon carinicauda

The Notch signaling pathway plays important roles in cell proliferation, differentiation and apoptosis. To explore the regulatory mechanism of the Notch signaling pathway in the growth and development of crustaceans, notch1 was cloned from Exopalaemon carinicauda by 5′/3′ RACE and its roles in growth and development were studied by qPCR, RNA interference and in situ hybridization. The results showed that the full-length cDNA of notch1 in E. carinicauda was 7868 bp in length, encoding a total of 2504 amino acids, with a predicted molecular weight of 650.7 kDa and a theoretical isoelectric point of 5.38. Notch1 was expressed in all tested tissues, with the highest expression in the ovary. The expression of notch1 in the RNA interference group was significantly lower than that in the control group between 12 and 48 h post-notch1 interference. The expression levels of key genes in the Notch signaling pathway, including jagged, delta and strawberry notch1 (sbno1); genes related to growth and development including chh, gih and mih; and genes related to ovary development including vitellogenin and cathepsin L, decreased significantly between 12 and 24 h post-notch1 interference and were significantly lower than that in the control. In situ hybridization showed that notch1 was highly expressed on both follicles and the cell membrane. The results showed that notch1 was involved in the growth and development of E. carinicauda, especially in the development of ovaries. This study elucidates growth and development mechanism of crustaceans and provides a theoretical basis for the molecular breeding of E. carinicauda.

Effect of Exogenous Nitric Oxide on Enterocytozoon hepatopenaei Copy Numbers and Immunity of Exopalaemon carinicauda

To explore the effect of nitric oxide (NO) on Enterocytozoon hepatopenaei (EHP) invading the shrimp, sodium nitroprusside was used as an exogenous NO donor to investigate the effects of different concentrations (0 μg/L (control group), 0.3 μg/L, 0.6 μg/L, and 0.9 μg/L) of sodium nitroprusside on the EHP copy number and the structure in the hepatopancreas of Exopalaemon carinicauda infected by EHP. The results showed that the EHP copy number in the sodium nitroprusside group was significantly lower than that in the control group, and the hepatopancreas in the sodium nitroprusside injection group had less structure damage than the control group. Additionally, superoxide dismutase (SOD) activity in the control group and 0.3 μg/L groups increased and then decreased, while alkaline phosphatase (AKP) activity decreased and then increased, with the same trend, and, the inducible nitric oxide synthase (iNOS) activity in the haemolymph of the 0.3 μg/L group was significantly higher than that of the control group at 3 days ( P &lt; 0.05 ). The NO content the 0.3 μg/L group was also higher from 1 to 4 days than that in the control group and significantly higher than that in the control group at 3 days ( P &lt; 0.05 ). The injection of NO could reduce the EHP copy number in infected E. carinicauda and slow down the pathological changes in the hepatopancreas structure, which might be related to the increase in NO content.

The ubiquitin-like, containing PHD and RING finger domains 1 (uhrf1) gene promotes ovarian development in Exopalaemon carinicauda

Ridgetail white prawn, Exopalaemon carinicauda, with high reproductive capacity can reproduce up to three or four generations a year. In exploring the genetic factors affecting the gonadal development of E. carinicauda, we cloned and studied the function of the ubiquitin-like, containing PHD and RING finger domains 1 (uhrf1) gene. The open reading frame of uhrf1 gene was 2286 bp, encoding a total of 761 amino acids. The Uhrf1 has UBL, TTD, PhD, SRA, and ring finger domains that are associated with genome methylation, histone recognition and chromatin modification. According to the phylogenetic analysis, the amino acid sequence of Ec-uhrf1 has the highest similarity with Litopenaeus vannamei uhrf1, and it is a branch of Penaeus monodon and L. vannamei. The real-time quantitative PCR showed that the expression level of uhrf1 was highest in ridgetail white prawn ovarian tissue, which was significantly higher than that of other tissues (P < 0.05). In addition, the expression level gradually increased in stages I-IV of ovarian development, with its expression level in stage IV being significantly higher than that in other stages (P < 0.05). RNAi results showed that a knockdown of uhrf1 gene expression significantly reduced the expression of the cell proliferation-related gene pcna, the DNA methylation-related gene dnmt1 and yolk synthesis related genes vg, indicating that uhrf1 regulates the expression of pcna and dnmt1. The in situ hybridization tests further indicated that the uhrf1 gene plays an important role in oocyte proliferation and accumulation of exogenous nutrients.

Transcriptomic and Metabolomic Analyses of Palaemon carinicauda Hepatopancreas in Response to Enterocytozoon hepatopenaei (EHP) Infection

Enterocytozoon hepatopenaei (EHP), a microsporidian responsible for hepatopancreatic microsporidiosis, is a major pathogen in commercial shrimp production. Among the affected species, Palaemon carinicauda (formerly Exopalaemon carinicauda) is commercially important in China and represents a potential research model for studying crustaceans. However, little information is available on its response to EHP infection. Hence, this study analyzed the transcriptome and metabolome of P. carinicauda’s hepatopancreas using high-throughput sequencing and liquid chromatograph-mass spectrometry (LC-MS) to determine its response during the early stage of infection. The transcriptomic analyses identified 730 differentially expressed genes, of which those associated with EHP infection were enriched in metabolic pathways as well as detoxification and antioxidant pathways. In addition, 144 differential metabolites were identified using a combination of positive and negative ion modes in LC-MS. The Kyoto encyclopedia of genes and genomes pathway analyses further indicated that the degradation of aromatic compounds, the AMP-activated protein kinase signaling pathway and C5-branched dibasic acid metabolism were significantly enriched after EHP infection. These results could provide useful insights into the effects of EHP on shrimps during the early stages of infection and help to understand the mechanisms underlying the stunted growth of shrimps after infection.

Characterization and expression analysis of β-catenin from Exopalaemon carinicauda (Holthuis, 1950) (Caridea, Palaemonidae) in embryonic development and immune response to bacteria

Abstract β-catenin is an important signal transduction protein in the canonical Wnt/β-catenin pathway, which is widely involved in the development of animals. However, the role of β-catenin in crustaceans is still unclear. In this study, the cDNA of β-catenin from Exopalaemon carinicauda (Holthuis, 1950) was identified and characterized. The open reading frame (ORF) is 2424 bp, which encodes 807 amino acids containing an N-terminal region of a GSK-β consensus phosphorylation site and a central region of 11 armadillo (ARM) repeats. The tissue distribution showed that β-catenin was highly expressed in ovary, testis, hepatopancreas, heart, and gills. During embryonic development, the transcript of β-catenin was relatively high in the zygote, and the thirty-two-cell stage, blastula stage, gastrula stage, and nauplius stage. The transcripts of β-catenin in haemocytes, gills, and hepatopancreas were significantly up-regulated after infection with Vibrio anguillarum Bergeman, 1909. These results indicate that β-catenin participates in the regulation of embryonic development and in the immune response in E. carinicauda.

Isolation and characterization of the actinomycete, Nocardiopsis, from Haizhou Bay, and its application as a probiotic for Exopalaemon carinicauda (Holthuis, 1950) (Caridea, Palaemonidae)

Abstract Actinomycetes, as the main producers of a variety of active metabolites and enzymes, have received extensive attention in aquaculture. An actinomycete had been isolated from Haizhou Bay and been identified by morphological analysis and 16S rRNA sequencing. Results showed that the actinomycete had the highest similarity (99.65%) with Nocardiopsis sp. and was named strain E10. Strain E10 produced an exo-enzyme with proteinase effect that showed strong antibacterial activity against Vibrio anguillarum. This strain E10 was tested as a probiotic for the culture of Exopalaemon carinicauda. After having been fed with a diet supplemented with strain E10 for 30 days, the final body weight (Wt), weight gain rate (WGR), special growth rate (SGR), survival rate (SR) and digestive enzymes (chymotrypsin, α-amylase and lipase) of E. carinicauda in all experimental groups showed no significant differences (). However, the antioxidant enzymes (total superoxide dismutase, catalase and peroxidase) and the non-specific immune-related enzymes (acid phosphatase, alkaline phosphatase and lysozyme) in the treatment groups increased significantly () compared with the control group. The cumulative mortality of the treatment groups (35.56% in 5 × 109 CFU/100 g) was significantly lower than that of the control treatment (73.33%) () post challenge with V. anguillarum for 14 days. The results indicated that strain E10 had no significant effect on the growth, but a significant improvement on the immunity of E. carinicauda. This study provides the data for ecological aquaculture of E. carinicauda.