Kuruma Shrimp Marsupenaeus Japonicus Research Articles

Isolation and molecular characterization of hemocyte sub-populations in kuruma shrimp Marsupenaeus japonicus

Crustacean hemocytes, which have usually been classified morphologically based on methods using Giemsa or May-Giemsa stains, have recently been categorized using monoclonal antibodies or marker genes. However, these latter techniques are not yet widely used, and different classification methods are used for hemocytes among laboratories. Therefore, we aimed to develop a molecular classification method that can be widely used by researchers. The method we have developed uses lectins and magnetic-activated cell sorting (MACS) to isolate sub-populations of hemocytes. Two lectins, wheat germ agglutinin (WGA) and tomato lectin (Lycopersicon esculentum lectin; LEL), characteristically bind to hemocytes, which allows them to be classified into three sub-populations. Furthermore, different sub-populations of hemocyte can be isolated by using LEL and MACS. These sub-populations were characterized as non-granular and granular hemocytes, and the accumulation patterns of the gene transcripts were consistent with the results of a functional analysis reported previously. The lectin-based hemocyte isolation method developed in this study has good reproducibility.

Methane fluxes from typical marine polyculture ponds of swimming crab with kuruma shrimp and short-necked clam in eastern China

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 11:63-73 (2019) - DOI: https://doi.org/10.3354/aei00295 Methane fluxes from typical marine polyculture ponds of swimming crab with kuruma shrimp and short-necked clam in eastern China Dongxu Zhang1, Xiangli Tian1,*, Shuanglin Dong1, Yan Chen2, Jie Feng1, Rui-Peng He1, Kai Zhang3 1Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, PR China 2Beijing Aquatic Product Technology Promotion Department, Beijing 100029, PR China 3Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, PR China *Corresponding author: xianglitian@ouc.edu.cn ABSTRACT: Methane (CH4) fluxes at the water-air interface in 2 typical seawater polyculture systems were determined during the farming season. The mean CH4 fluxes were 66.0 ± 44.1 µg m-2 h-1 in the bispecies polyculture system of swimming crab Portunus trituberculatus with kuruma shrimp Marsupenaeus japonicus (PM) and 68.7 ± 39.5 µg m-2 h-1 in the trispecies polyculture system of swimming crab with shrimp and short-necked clam Ruditapes philippinarum (PMR), and no significant differences were observed between them. CH4 emissions showed temporal variability during the farming season, peaking in mid-August. The linear mixed-effect model demonstrated that air temperature was the main regulator of CH4 fluxes rather than the internal physical and chemical properties of the systems. Air, water and sediment temperatures explained 58.9, 61.4 and 55.3% of the CH4 flux variations in the PM and 64.6, 57.1 and 60.8% of the variations in the PMR, respectively. Reducing organic matter accumulation in the sediment by means of improving feeding efficiency and the application of integrated aquaculture are likely to be effective in reducing CH4 emissions from aquaculture systems. KEY WORDS: Methane fluxes · Temperature · Sediment characteristics · Seawater polyculture systems Full text in pdf format PreviousNextCite this article as: Zhang D, Tian X, Dong S, Chen Y, Feng J, He RP, Zhang K (2019) Methane fluxes from typical marine polyculture ponds of swimming crab with kuruma shrimp and short-necked clam in eastern China. Aquacult Environ Interact 11:63-73. https://doi.org/10.3354/aei00295 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 11. Online publication date: February 21, 2019 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2019 Inter-Research.

Comparative transcriptomic analysis of Marsupenaeus japonicus hepatopancreas in response to Vibrio parahaemolyticus and white spot syndrome virus

Vibrio parahaemolyticus and white spot syndrome virus (WSSV) are pathogens that cause epidemics in kuruma shrimp (Marsupenaeus japonicus) during aquaculture, resulting in severe economic losses to local farmers. To characterise the mechanisms of the molecular responses to V. parahaemolyticus and WSSV infection in M. japonicus, the transcriptome of hepatopancreas was sequenced using next-generation sequencing after infection. A total of 29,180 unigenes were assembled, with an average length of 1,151 bp (N50 = 1,951 bp). After BLASTX searching against the Nr database (E-value cut-off = 10−5), 15,176 assembled unigenes remained, with 3,039 and 1,803 differentially expressed transcripts identified in the V. parahaemolyticus- and WSSV-infected groups, respectively. Of these, 1466 transcripts were up-regulated and 1573 were down-regulated in V. parahaemolyticus-infected shrimps, and 970 transcripts were up-regulated and 833 were down-regulated in the WSSV-infected shrimps. Additionally, 761 transcripts were differentially expressed in both V. parahaemolyticus- and WSSV-infected shrimps. Several known immune-related genes including caspase 4, integrin, crustin, ubiquitin-conjugating enzyme E2, C-type lectin, and α2-macroglobulin were among the differentially expressed transcripts. These results provide valuable information for characterising the immune mechanisms of the shrimp responses of to V. parahaemolyticus andWSSV infection.

Effects of dietary astaxanthin and vitamin E and their interactions on the growth performance, pigmentation, digestive enzyme activity of kuruma shrimp (Marsupenaeus japonicus )

A 56-day feeding trial was done to investigate the interactive effects of astaxanthin (Ax) and vitamin E (α-Toc) on the performance of kuruma shrimp (Marsupenaeus japonicus). A 2 × 3 factorial experiment was conducted with six experimental diets containing two levels of Ax (0 and 0.6 g/kg diet [Ax0 and Ax0.6]) and three levels of α-Toc (0, 0.2 and 1 g/kg diet [α-Toc0, α-Toc0.2 and α-Toc1]). The results indicated that growth performance was significantly (p < 0.05) increased in shrimp fed with the Ax0.6 × α-Toc0.2 diet. Interactive effects between Ax and α-Toc on the growth parameters were observed. Furthermore, pigmentation performance was significantly (p < 0.05) better in the Ax0.6 groups. Interaction between Ax and α-Toc was also found in the Ax content of shrimp body parts. Interestingly, dietary α-Toc helped to reduce the Ax consumption rate, promote the absorption and increase the deposition of Ax in the muscle. Shrimps from the Ax0.6 groups showed significantly (p < 0.05) improved hepatopancreatic digestive enzyme activities compared with those of the Ax0 groups. Although no interactive (p > 0.05) effects were found between dietary α-Toc and Ax on total haemocyte count and tolerance against freshwater, dietary Ax and α-Toc supplementation showed better performance on these two parameters. It was concluded that dietary Ax and α-Toc functioned synergistically, and the shrimp fed with the diet containing 0.6 g Ax/kg diet Ax and 0.2 g α-Toc/kg diet showed improved growth and pigmentation performance compared with the other groups in the current study.

Effects of thermal stress on oxidative stress and antioxidant response, heat shock proteins expression profiles and histological changes in Marsupenaeus japonicus

Water temperature is a crucial ecological factor in aquatic environments. In the context of global warming, aquatic organisms are inevitably subject to thermal stress. The kuruma shrimp Marsupenaeus japonicus is an important commercial crustacean and has become one of the most important species in shrimp fisheries and aquaculture in China. However, M. japonicus showed relatively poor thermotolerance and frequently suffers mass mortalities during the summer months. The thermally sensitive properties of this species also make it a potential indicator species to reflect thermal alteration. Since this species raises both commercial and scientific interests, we investigated the effects of thermal stress on M. japonicus with special emphases on oxidative stress and antioxidant response, heat shock proteins expression profiles and histological changes. The results revealed that transcription of antioxidant enzymes (MjSeGpx and MjGSTMu) and heat shock proteins (Mjhsp60, Mjhsp70 and Mjhsp90) were all dramatically induced in both hepatopancreas and gill of M. japonicus under thermal stress with various expression patterns, and the up-regulated extent of the five genes exhibited a tendency of increasing with temperature. Several oxidative stress biomarkers, including MDA content, CAT activity, SOD activity and GST activity were assessed. The CAT activity was found to be more inducible than SOD and GST activities under thermal stress. In contrast to the higher basal antioxidant enzymes activities in the gill than that in the hepatopancreas, the hepatopancreas exhibited higher MDA content than that of gill. In consistent with the relatively higher MDA content, histological alterations appeared in the hepatopancreas of M. japonicus under thermal stress. This study provided comprehensive clues for uncovering the mechanisms underlying the thermal stress response and summer mortality syndrome of M. japonicus and evaluating the bioindicator potential of this species.

Insights into the intestine immune of Marsupenaeus japonicus under the white spot syndrome virus challenge using RNA sequencing

Intestine is not only the nutrients digestion and absorption centers, but also an important place of microbial infection. Therefore, intestine immunity plays a key defense means for the host against the invasion of pathogenic microorganisms. In this study, we use kuruma shrimp (Marsupenaeus japonicus) as a model to study the intestine immune characteristics of shrimp against WSSV through next-generation sequencing technique. A total of 63,458 and 44,350 unigenes were generated from the control sample and the WSSV infection sample, respectively. Based on homology searches, KEGG, GO, and COG analysis, 39,520 unigenes were annotated. Among them, 12,920 differentially expressed genes were identified. Some of them, including mucin, peritrophin, chitinase, et al., are involved in immune response. These results contribute to a better understanding of the intestine immune response of the shrimp to WSSV.

Comparative transcriptome analysis provides comprehensive insights into the heat stress response of Marsupenaeus japonicus

The kuruma shrimp Marsupenaeus japonicus is an economically important crustacean that is widely distributed throughout the Indo-West Pacific. However, M. japonicus exhibits relatively poor thermotolerance properties and frequently suffers from mass mortality during the hot summer months in aquaculture systems. Herein, we performed a comparative transcriptome analysis of M. japonicus in response to heat stress, focusing on immune responses, heat shock proteins, antioxidant systems and metabolism alterations under heat stress. The results revealed that M. japonicus generated adaptive responses to maintain physiological homeostasis under heat stress via the transcriptional up-regulation of heat shock proteins and antioxidant enzymes, enhancement of fatty acid metabolism. However, acute and prolonged exposure to heat stress resulted in the continually decreased expression of immune molecules and led to the repression of glycometabolism, the tricarboxylic acid cycle and the respiratory chain. This study provides a systematic overview of the M. japonicus heat stress response and elucidates potential molecular mechanisms underlying this phenomenon and summer mortality syndrome in this species, which is beneficial for proposing effective strategies to address summer mortality syndrome and promote kuruma shrimp production.

Cloning and functional characterization of thioredoxin gene from kuruma shrimp Marsupenaeus japonicus

As an important disulfide reductase of the intracellular antioxidant system, Thioredoxin (Trx) plays an important role in maintaining oxidative stress balance and protecting cells from oxidative damage. In recent years, there is increasing evidence that Trx is a key molecule in the pathogenesis of various diseases and a potential therapeutic target for major diseases including lung, colon, cervical, gastric and pancreatic cancer. However, few knowledge is known about the function of Trx in virus infection. In this study, we reported the cloning and functional investigation of a Trx homologue gene, named MjTrx, in shrimp Marsupenaeus japonicus suffered white spot syndrome virus (WSSV) infection. MjTrx is a 105-amino acid polypeptide with a conservative Cys-Gly-Pro-Cys motif in the catalytic center. Phylogenetic trees analysis showed that MjTrx has a higher relationship with Trx from other invertebrate and clustered with Trx1 from arthropod. MjTrx transcripts is abundant in the gill and intestine tissues and can be detected in the hemocytes, heart, stomach, and hepatopancreas tissues. The transcription levels of MjTrx in hemocytes, gills and intestine tissues of shrimp were significantly up-regulated after white spot syndrome virus infection. MjTrx was recombinant expressed in vitro and exhibited obvious disulfide reductase activity. In addition, overexpression MjTrx in shrimp resulted in the increase of hydrogen peroxide (H2O2) concentration in vivo. All these results strongly suggested that MjTrx functioned in redox homeostasis regulating and played an important role in shrimp antiviral immunity.

Genetic parameters for growth‐related traits and survival with age in the Kuruma shrimp Marsupenaeus japonicus

Genetic parameters were estimated for growth-related traits and survival of the Kuruma shrimp Marsupenaeus japonicus based on 66 families, including 30 paternal half-sib families, which were obtained using artificial insemination of two females by each male. The variance components for growth-related trait and survival were estimated using a single-trait animal model and a sir-dam model, respectively, and genetic parameters were estimated using the restricted maximum likelihood method. The coefficients of variation for growth-related traits such as body length (BL), abdominal length (AL), and body weight (BW) were 9.36%–22.44%, 10.61%–21.92%, and 26.47%–58.33%, respectively, at different ages (45, 75, 105, 135, and 165 days). The corresponding heritability estimates for each growth trait were 0.1545–0.1951, 0.1672–0.1905, and 0.1596–0.1934, respectively, all of which were found to be at moderate levels and increased with age. The heritability of survival on day 165 was low (0.003). The genetic correlations among growth traits were positive and high (0.7316–0.9896) at the different ages, suggesting that selection to improve any single growth trait will cause positive responses in other growth traits examined in M. japonicus. The genetic correlations between growth traits and survival were also positive but low (0.005–0.087), which indicated that only selecting for growth traits may not cause a positive correlated response in the survival of the core population. According to the above results, we suggested that growth and survival traits should be taken as improving targets of breeding in M. japonicus. These results provided reference data for selective breeding and multitrait selection of M. japonicus.

Protein Inhibitor of Activated STAT (PIAS) Negatively Regulates the JAK/STAT Pathway by Inhibiting STAT Phosphorylation and Translocation

Protein inhibitor of activated STAT (PIAS) proteins are activation-suppressing proteins for signal transducer and activator of transcription (STAT), which involves gene transcriptional regulation. The inhibitory mechanism of PIAS proteins in the Janus kinase (JAK)/STAT signaling pathway has been well studied in mammals and Drosophila. However, the roles of PIAS in crustaceans are unclear. In the present study, we identified PIAS in kuruma shrimp Marsupenaeus japonicus and found that its relative expression could be induced by Vibrio anguillarum stimulation. To explore the function of PIAS in shrimp infected with V. anguillarum, we performed an RNA interference assay. After knockdown of PIAS expression in shrimp subjected to V. anguillarum infection, bacterial clearance was enhanced and the survival rate increased compared with those in the control shrimp (dsGFP injection). Simultaneously, the expression levels of antimicrobial peptides (AMPs), including anti-lipopolysaccharide factor (ALF) A1, C1, C2, and CruI-1, increased. Further study revealed that knockdown of PIAS also enhanced STAT phosphorylation and translocation. Pulldown assay indicated that PIAS interacts with activated STAT in shrimp. In conclusion, PIAS negatively regulates JAK/STAT signaling by inhibiting the phosphorylation and translocation of STAT through the interaction between PIAS and STAT, which leads to the reduction of AMP expression in shrimp. Our results revealed a new mechanism of PIAS-mediated gene regulation of the STAT signal pathway.

Efficacy of dietary fermented vegetable product on immune response, up-regulation of immune-related genes and protection of kuruma shrimp (Marsupenaeus japonicus) against Vibrio parahaemolyticus

The present study was carried out to investigate the effects of dietary fermented vegetable product (FVP) on the innate immune response, immune-related genes expression and resistance of kuruma shrimp Marsupenaeus japonicus against Vibrio parahaemolyticus. Four hundred and eighty healthy kuruma shrimp (15.3 ± 1.15 g) were distributed into four treatment groups and fed with diets containing 0 (control), 0.55, 5.5, and 55 g FVP (kg diet)−1 for 11 days. The results revealed that administration of FVP significantly elevated the innate immune parameters of kuruma shrimp including total hemocyte count (THC), phagocytosis, phenoloxidase activity, reactive oxygen species (ROS) production and bactericidal activity (P < 0.05). Furthermore, dietary supplementation of 5.5, and 55 g FVP (kg diet)−1 remarkably up-regulated the expression of antimicrobial peptides (AMPs) and toll-like receptors (TLR) in various tissues, particularly in the intestine. Shrimp groups supplemented with FVP diets showed significantly lower cumulative mortality percentage after being challenged with Vibrio parahaemolyticus (P < 0.05). The results suggest that FVP can be recommended as a feed supplement to elevate innate immune response, upregulate immune related genes expression and increase disease resistance in kuruma shrimp.

Laboratory Scale Culture of Early-Stage Kuruma Shrimp Marsupenaeus japonicus Larvae Fed on Thraustochytrids Aurantiochytrium and Parietichytrium

Early-stage larvae of the Kuruma shrimp Marsupenaeus japonicus are cultured up to mysis stages on microalgae, including Chaetoceros calcitrans, Chaetoceros gracilis, and/or Tetraselmis tetrathele, as food sources. Microalgal proliferation is affected by weather conditions, making stable and systematic production of both the microalgae and M. japonicus larvae difficult. The Thraustochytrids are a group of heterotrophic protists that include the genera Aurantiochytrium and Parietichytrium. The Thraustochytrids contain large quantities of n-3 highly unsaturated fatty acids, especially docosahexaenoic acid, an important nutritional component for the growth and physiological function of marine animals. Because the Thraustochytrids are heterotrophic and multiply rapidly in artificially controlled environments, their large scale culture is easy, stable, and systematic. To determine if Aurantiochytrium and Parietichytrium can be used instead of microalgae as a diet for early stage M. japonicus larvae, these larvae were reared in the laboratory on a diet containing C. calcitrans or strains of Aurantiochytrium or Parietichytrium, and their survival, development, and growth were compared. Larvae fed on the KOU10 strain of Parietichytrium sp. showed significantly greater survival, development, and growth than larvae fed on other diets, including those containing C. calcitrans. Although the mechanism by which the KOU10 strain enhanced the survival and growth performances of M. japonicus larvae is presently unclear, these larvae may be stably and systematically cultured on diets containing Parietichytrium instead of microalgae.

Myeloid leukemia factor participates in the antibacterial immune reaction of kuruma shrimp marsupenaeus japonicus.

Myeloid leukemia factor (MLF) plays an important role in the development of Drosophila. It is reported that MLF could inhibit white spot syndrome virus (WSSV) replication in shrimp. However, the function and mechanism of MLF in shrimp antibacterial immunity are still elusive. In this study, we found MjMLF could be upregulated by Vibro anguillarum challenge in hemocytes, gills, and intestine of kuruma shrimp. RNAi assay showed that MjMLF could facilitate bacterial clearance in shrimp, and it was beneficial for shrimp survival post V. anguillarum infection. Pull down assay showed that rMjMLF could bind to rMj14-3-3 in vitro. Some antimicrobial peptide genes could be regulated by MjMLF. The results indicated that MjMLF might participate in the anti-bacterial immune reaction of shrimp.

Comparative sequence analysis of crustin isoform MjCRS7 and MjWFDC-like gene from kuruma shrimp Marsupenaeus japonicus shows variant of the WFDC domain

Crustins are well known cysteine-rich cationic antimicrobial peptides (AMPs) in crustaceans that have WFDC [WAP (whey acidic protein) four-disulfide core] domain at the carboxyl terminus. Proteins containing a WFDC domain have been discovered in many invertebrates and vertebrates. Although, there have been many WFDC domain containing nucleotide sequences found in NCBI GenBank database, their distinct sequential characteristics and their role in the innate immune system is not well understood. Here, we identified a new crustin isoform from Marsupenaeus japonicus by transcriptome analysis. The full-length cDNA of this isoform (MjCRS7) consists of 537 bp that include a 489 bp open reading frame (ORF) encoding 162 deduced amino acids (aa). The sequence contains the eight conserved cysteine residues characteristic of the WFDC domain. A phylogenetic analysis showed that MjCRS7 is a type II crustin. We also identified the full-length cDNA of a M. japonicus MjWFDC-like gene. MjWFDC-like has a 543 bp ORF encoding 180 aa. In an RT-PCR analysis, MjCRS7 and MjWFDC-like transcripts were mainly detected in gill tissue. An alignment of MjCRS7 and MjWFDC-like with previously reported M. japonicus crustin isoform 1–5 (MjCRS1–5) showed variation in the WFDC-like domain. Neither of the genes was responsive to Vibrio parahaemolyticus, Vibrio penaeicida or white spot syndrome virus (WSSV) either by immersion or injection challenge test. Although crustins are mainly antimicrobial peptides, the present results suggest that MjCRS7 may have other roles in M. japonicus.

Molecular characterization and gene expression analysis of hypoxia-inducible factor and its inhibitory factors in kuruma shrimp Marsupenaeus japonicus

In shrimp aquaculture, overcrowded farming causes fluctuations in dissolved oxygen concentrations. Low-oxygen conditions (hypoxia) affect shrimp growth. Hypoxia-inducible factor (HIF) is a transcriptional factor in the basic helix-loop-helix/PAS family and is activated in response to hypoxic stress. However, little is known about HIF and other inhibitors of the HIF pathway in crustaceans. In this study, we cloned MjHIF-1α, an inhibitory factor, MjFIH-1 (factor inhibiting HIF-1α), and MjVHL (Von Hippel-Lindau tumor suppressor) from kuruma shrimp (Marsupenaeus japonicus). MjVHL is the first crustacean VHL ortholog to be cloned. MjHIF-1α, MjFIH-1, and MjVHL exhibit significant sequence similarity and share key functional domains with previously described vertebrate and invertebrate genes. As a result of gene expression analysis in various tissues, MjHIF-1α and MjVHL were more highly expressed in the intestine than in any other organ tissues. In hypoxia experiments, HIF-induced expression levels of MjHIF-1α in the hypoxic group increased significantly for 24 h after initiating hypoxia stimulation and expression of MjVHL decreased significantly for 6 h after hypoxia stimulation (P < 0.05).

Effects of the Dietary Probiotic Clostridium butyricum on Intestine Digestive and Metabolic Capacities, SCFA Content and Body Composition in Marsupenaeus japonicus

A 56-day feeding trial was performed to evaluate the effects of dietary probiotic Clostridium butyricum (CB) on intestine digestive and metabolic capacities, intestine short-chain fatty acids (SCFA) content and body composition of kuruma shrimp Marsupenaeus japonicus. Shrimps were randomly allocated into 9 tanks, 30 each, and fed with diets containing different levels of C. butyricum (1 × 109 cfu g−1): 0 mg g−1 feed (Control), 100 mg g−1 feed (CB-100), 200 mg g−1 feed (CB-200), while each level was triplicated. The results indicated that compared with the control group, the intestine pepsin (Pep) activity and 5-hydroxytryptamine (5-HT) concentration of two C. butyricum groups were both increased. Amylase (AMY) and lipase (LPS) activities were only induced in CB-200 group. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities of two C. butyricum groups showed no significant change. The α-amylase (AMY) gene expression was induced in CB-200 group, and trypsin gene expression of two C. butyricum treated groups were both induced. Intestine SCFA content and body composition analysis showed that the contents of propionic acid, butyric acid and the crude protein of two C. butyricum groups were all higher than those of control. These results revealed that C. butyricum can modulate intestine digestive and metabolic capacities, improve intestine SCFA content and body crude protein content in M. japonicus.

The immune functions of sessile hemocytes in three organs of kuruma shrimp Marsupenaeus japonicus differ from those of circulating hemocytes

Shrimp, as invertebrates, have an open vasculature that allows circulating hemocytes to infiltrate the tissues, where they are referred to as sessile hemocytes. Sessile hemocytes are known to express immune-related genes, but it is not known whether their functions differ from those of circulating hemocytes. To answer this question, we enriched them from suspensions of different tissues using discontinuous density gradient centrifugation and analyzed their transcripts by RNA-seq. The results suggest that circulating hemocytes and sessile hemocytes of the gills are in a state that could react quickly to pathogens, immune-related genes expression of sessile hemocytes differ from circulating hemocytes, and the gills, heart and lymphoid organs have cells that express immune-related genes that are different from hemocytes.

Effects of dietary astaxanthin supplementation on survival, growth and stress resistance in larval and post-larval kuruma shrimp, Marsupenaeus japonicus

Two trials were conducted to evaluate the effects of chemically synthesized astaxanthin (Ax) on growth performance, survival, and stress resistance in larval and post-larval kuruma shrimp (Marsupenaeus japonicus). Six dietary levels of Ax (0, 50, 100, 200, 400 and 800 mg/kg diet) were added to a baseline diet. As a first study, an 8-day feeding trial was conducted on larval kuruma shrimp, with results showing that larvae-fed diets supplemented with different Ax levels exhibited better performance during developmental and metamorphosis to postlarvae. Broken-line regression analysis indicated that the optimal levels for growth and stress resistance of larvae were 168.9 mg/kg and 82.1 mg/kg diet, respectively. Second, a 30-day feeding trial was conducted on post-larval shrimp. Supplementation with 100 and 200 mg/kg Ax yielded significantly higher final body weight, body weight gain and specific growth rate than that in a control group. A cumulative mortality index for osmotic stress revealed significantly better performance in a group fed 200 mg/kg supplementation than in controls. Broken-line regression analysis indicated that the optimal levels for growth and stress resistance of postlarvae were 108.7 mg/kg and 178.1 mg/kg diet, respectively. Based on these results, we suggest that carefully dosed Ax supplementation is a beneficial nutritional strategy for the early developmental stages of kuruma shrimp.

Gills specific type 2 crustin isoforms: Its molecular cloning and characterization from kuruma shrimp Marsupenaeus japonicus

Crustins are diverse group of antimicrobial peptides (AMPs) that have numerous isoforms mainly identified from hemocytes in decapods crustacean. However, little is known about its presence solely in gills tissue. In this study, we found two new crustin isoforms MjCRS8 and MjCRS9 by using transcriptome analysis from gills. Open reading frame of MjCRS8 and MjCRS9 were 593 bp and 459 bp encoding 197aa and 152aa, respectively. Tissue distribution analysis indicated that both MjCRS8 and MjCRS9 are expressed only in gills tissue. Multiple sequence alignment and phylogenetic analysis with previously reported crustin suggested that both MjCRS8 and MjCRS9 belong to type 2 crustin family. Experimental infection was conducted against Vibrio parahaemolyticus and white spot syndrome virus (WSSV) by immersion test. However, no significant upregulation was observed.

Effects of dietary astaxanthin supplementation on juvenile kuruma shrimp, Marsupenaeus japonicus

This study evaluated the effects of chemically synthesized astaxanthin (Ax) on growth performance, survival, stress resistance, immune responses, fatty acid contents, and pigmentation of juvenile kuruma shrimp (Marsupenaeus japonicus). Six dietary levels of Ax (0, 200, 400, 800, 1200, and 1600 mg kg−1 diet) were added to a baseline diet. The feeding trial was conducted for 56 days. The results showed that juveniles fed diets supplemented with Ax exhibited better growth performance, final body weight (FBW), body weight gain (BWG), and specific growth rate (SGR) than the control group, with the best performance exhibited by in the 400 mg kg−1 diet Ax supplemented group (P < 0.05). Following fresh water-osmotic stress test, the 200, 400, and 800 mg kg−1 diet Ax supplemented groups showed higher LT50 values than the other groups. The 400, 800, and 1200 mg kg−1 diet Ax supplemented groups exhibited different immune responses (total hemocyte count [THC] and viable cells [VC]) to the control group. The Ax content of the whole shrimp body increased with increasing supplemented levels. After cooking, shrimp fed diets containing Ax were a strong red in color, while the control group was light pink in color. The colorimetric reading of the body and head of cooked shrimp showed that redness (a*) and yellowness (b*) increased with increasing dietary Ax supplementation. The 1200 and 1600 mg kg−1 diet supplemented groups were also significantly different from the control group for these two parameters in both shrimp body and head. Broken-line regression analysis indicated that the optimal levels for growth, immune responses, and pigmentation were 401, 420, and 404 mg kg−1 diet, respectively. In conclusion, the optimum diet supplementation level of the Ax to enhance the performance of juvenile kuruma shrimp is around 400 mg kg−1.