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In the selective breeding program of Chinese shrimp Fenneropenaeus chinensis , selection candidates from the same family were reared in a separate unit to maintain a high level of biosecurity, and their phenotypes cannot be directly compared with each other and cannot be used for genetic evaluation. Therefore, selection accuracy for selection candidates was restricted when their genetic merits were evaluated by pedigree-based best linear unbiased prediction (PBLUP). Genomic selection may improve selection accuracy for selection candidates by quantifying Mendelian sampling across siblings using genome-wide markers. In this study, genomic BLUP (GBLUP) and single-step GBLUP (ssGBLUP) were used to predict the genomic estimated breeding values (GEBVs) of body weight of full-sib selection candidates of F. chinensis, and their prediction abilities were evaluated by progeny testing. The validation population consisted of 103 genotyped individuals without body weights in the G11 generation. The predicted GEBVs (EBVs) of body weight were obtained using the ssGBLUP, GBLUP, or PBLUP method with a reference population consisting of 8133 non-genotyped individuals and 285 genotyped individuals over 3 generations (G9-G11). The progeny-based EBVs (PEBVs) of the validation individuals were calculated using PBLUP with 4959 progenies in the G12 generation. The prediction accuracy was evaluated by the correlation between GEBVs (EBVs) and PEBVs. Variance components for body weight were also estimated using the average information REML method with a relationship matrix (A or H) and an animal model. The results showed that the body weight heritabilities obtained using the A and H matrix were 0.11 ± 0.04 and 0.18 ± 0.05, respectively. The prediction accuracy of GBLUP and ssGBLUP outperformed PBLUP by 10.72% and 29.60%, respectively. Furthermore, when the phenotypes of genotyped individuals in the reference population were masked, the prediction accuracy of ssGBLUP was still 17.72% higher than that of PBLUP. Progeny testing suggested that genomic-based prediction methods may improve selection accuracy for the selection candidates of F. chinensis under biosecurity restrictions. • First report of using progeny data to evaluate the prediction ability of genomic evaluation methods in shrimp. • The prediction accuracy of ssGBLUP and GBLUP outperformed PBLUP for body weight by 29.60% and 10.72%, respectively. • Large reference and progeny population size and strong genetic ties between populations resulted in high accuracy (0.56). [ABSTRACT FROM AUTHOR]

Genetic parameters and predicted and realized selection responses were estimated for harvest body weight of Chinese shrimp ( Fenneropenaeus chinensis ) after five generations of multi-trait selection. The body weights of 15,201 tagged shrimp representing 460 full-sib families in 6 generations were recorded at harvest. Heritability estimates for body weight showed large variation in magnitude (0.00 ± 0.00-0.36 ± 0.07) when analyzing data from each generation separately. When data from all generations (G 0 -G 5 ) were included in analysis, the heritability estimate for body weight was 0.18. While, G 0 was more affected by environmental conditions than the other generation in this study, when data from G 0 was excluded, the heritability was 0.21. The common environment effect estimate was 0.08 when all data included and 0.06 when G 1 -G 5 included. The females were significantly larger than the males at harvest ( P < 0.05). The genetic correlation of the harvest body weight between sexes was similar within and across generations, indicating that body weight in male and female shrimp is likely controlled by the same genes. Breeding candidates in the base population (G 0 ) were selected according to their individual breeding values for growth. In later generations (G 1 -G 5 ), candidates were selected according to a selection index including breeding values for growth, survival time after WSSV infection and pond survival. The response to selection for harvest body weight was estimated by two methods (the realized and predicted responses). The realized response was estimated from the differences in the least square means of body weight between the selection and control populations. The predicted response was obtained from the differences in the mean breeding values between generations. The accumulated realized response was 18.60% after performing five selections. The accumulated predicted responses estimated using two sets of genetic parameters obtained from within and across generation datasets were 6.43% and 6.50%, respectively. The results are discussed in a practical context of developing selective breeding programs for Chinese shrimp, and it is indicated that the selective breeding program has generated effective genetic improvement after five generations of selection. The future direction of the genetic improvement program is discussed. Statement of relevance Chinese shrimp, Fenneropenaeus chinensis , is one of the most valuable mariculture species in China. The Yellow Sea Fisheries Research Institute (Qingdao, China) initiated a multi-trait selective breeding program for Chinese shrimp in 2004, based on a combined family and within (inter) family selection scheme to improve growth, survival time after WSSV infection and pond survival. A new selected breed named “Huanghai No. 2” (registration no. GS01-002-2008) was approved in 2008. This program provided significant economic and social benefits. However, only limited results regarding this program have been reported, which involved genetic parameters of harvest body weight and genetic correlations among different traits using only one year data, a smaller subset of the current study. Growth is one of the most desirable economic traits in aquaculture. Good growth is important for efficient production and contributes to more profitable and sustainable development. Currently, the selective breeding program for F. chinensis is ongoing and the breeding nucleus was divided into different lines after performing five selections. In this paper, we will focus on the results related to genetic evaluation for the harvest body weights from G 0 to G 5 . We will present more reliable estimates of phenotypic and genetic parameters, calculate the response to selection after performing five selections and discuss the longer term implications of the findings from a genetic improvement viewpoint. [ABSTRACT FROM AUTHOR]

Abstract: Inbreeding effects on growth, survival and anti-WSSV (White Spot Syndrome Virus) traits were studied in experimental full-sibling inbred populations of Chinese shrimp Fenneropenaeus chinensis at three levels of inbreeding coefficient (F =0.25, F =0.375, F =0.50) from a Chinese shrimp selection program. The body weight of the control group (F ≈0.00) was significantly different from those of the three levels of inbreeding groups at three postlarval stages (PL80, PL100 and PL140). At PL140, an increasing inbreeding depression of growth was observed with increasing inbreeding coefficient. The inbreeding depression was found to be −10.4% at F =0.25, −16.61% at F =0.375 and −23.68% at F =0.50. There was also a tendency for inbreeding depression for body weight to increase with age. The estimated coefficient of body weight of PL140 were −4.16%, −4.43% and −4.74% per 10% increase of inbreeding coefficient of F =0.25, F =0.375, F =0.50, respectively. During growout, inbreeding depression of survival ranged from −0.98% to −12.44%, although the effects were not significant. Over all levels of inbreeding the average inbreeding depression was found to be −5.95% for survival of PL80, −5.51% for PL100 and −6.71% for PL140. The estimated average inbreeding depression coefficient of survival ranged from −1.27% to −1.77% per 10% increase of inbreeding coefficient of F, lower than the estimate obtained for growth. The effects of inbreeding on survival time after challenge with White Spot Syndrome Virus (WSSV) were not significant, as there was no significant difference in survivorship among the control and the three levels of inbreeding coefficient groups. The inbreeding depression of the three levels ranged from −0.68% to −2.22%, and the estimated inbreeding depression coefficient of survival time ranged from −0.27% to −0.44% per 10% increase of inbreeding coefficient of F. This study demonstrates that inbreeding has a negative effect on the economic traits, especially on growth, thus highlighting the need to maximize the genetic diversity in selective breeding programs. [Copyright &y& Elsevier]

Abstract: White spot syndrome virus (WSSV) is the most severe viral pathogen to the shrimp culture industry worldwide. The temporal and spatial dynamic changes of WSSV in Chinese shrimp Fenneropenaeus chinensis maintained at 22±1°C during infection via injection were studied through the quantitative real-time PCR method. The pleopods were selected for virus quantification at 0, 6, 12, 18, 24, 27, 30, 33, 36, 39, 42, 45 and 48hours post-injection (hpi). Besides the pleopod, different tissues including the hepatopancreas, nerve, heart, eyestalk, muscle, lymphoid organ, gut, stomach, gill and skin were also selected for viral load analysis at 0, 12, 27 and 30hpi as well as the moribund stage after 40hpi. The curve of viral load change in vivo assumed a very similar shape with the typical viral one-step growth curve. The infection process was classified into three stages: the light infection stage (0 to 18hpi) when the viral load in the pleopod was at the level of no more than 103/ng DNA and no mortality appeared; the moderate infection stage (18 to 45hpi), corresponding to the logarithmic phase of WSSV replication, when the viral load in the pleopod ranged from 103 to 105/ng DNA and a low mortality rate was observed; and the heavy infection stage when WSSV propagation went into the plateau phage and massive mortality happened. A turning point from chronic infection to acute infection was suggested from 27 to 30hpi when the viral load in most tissues increased substantially. The progress rate of WSSV in different tissues during the infection was different and the most favorite replication tissue of WSSV in early infection is the stomach, followed by the gill. The heaviest infected tissues are the skin, stomach and gill, explaining the symptoms of skin color changes, reduction of food consumption and gathering at the water surface due to dyspnea. The hepatopancreas, muscle and nerve were not the main replication sites in advanced infection. Also, the expression profiles of two anti-virus genes FcALF and FcAV were analyzed. This study might provide important data to study the virus infection mechanism. [Copyright &y& Elsevier]

Abstract: An integrin β subunit (FcβInt) cDNA was cloned from hemocytes of Fenneropenaeus chinensis by rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA of FcβInt consists of 2853bp and encodes a polypeptide of 783 amino acids with a predicted isoelectric point of 5.09. The deduced amino acid sequence of FcβInt possessed the classical domains of β integrin, including the βA domain and four epidermal-growth-factor (EGF)-like domains, which shared highest similarity with a β integrin of Pacifastacus leniusculus. The FcβInt mRNA was highly expressed in hemocytes, heart and gill, and moderately in gonad and intestine, whereas low expression level was found in muscle and hepatopancreas. FcβInt mRNA in gill was significantly up-regulated in 24h and then gradually decreased below the control level in response to WSSV challenge. The cDNA fragment encoding the extracellular region of FcβInt (FcβInt-ER) was expressed in Escherichia coli BL21 (DE3), and polyclonal antibodies against recombinant FcβInt-ER (rFcβInt-ER) were produced, which could specifically react to the hemocyte membrane by immunofluorescence assay and recognize a 120kDa protein in the hemocytes by western blotting. By ELISA and dot-blot binding assay, rFcβInt-ER exhibited specific WSSV binding activity. Neutralization assay in vivo further demonstrated that rFcβInt-ER could partially block WSSV infection to shrimp. These results suggested that FcβInt plays an important role in WSSV infection. [Copyright &y& Elsevier]

Abstract: ATP-binding cassette (ABC) transporters are integral membrane proteins which carry diverse substrates across biological membranes. In this study, we report the cloning of a full-length, 2122-bp cDNA sequence encoding a gene of the ABC transporter subfamily G (ABCG) from the shrimp Fenneropenaeus chinensis. The deduced protein, FcABCG, contains 633 amino acid residues with a theoretical molecular weight of 70.57kDa. Phylogenetic analysis showed that the FcABCG clusters with the shrimp Litopenaeus vannamei ABCG in the same clade and is more closely related to the insect ABC transporter/white proteins than to the ABCG2 of the fish Salmo salar. High-level mRNA expression of FcABCG was detected in the tissues of hepatopancreas and intestine using a real-time quantitative reverse transcriptase PCR. Furthermore, exposure to alkaline pH stress conditions and norfloxacin diets result in the activation of the FcABCG gene in F. chinensis. These results suggest that the ABCG transporter of F. chinensis might play a role in coping high pH stress and in exporting xenobiotics. [Copyright &y& Elsevier]

Abstract: The vasa gene, a member of the DEAD-box gene family, has been reported to be restricted exclusively to the germ cell lineage in most animals, and thus is the most reliable molecular marker for studies on germ cell development. In this study, the developmental expression pattern of the vasa-like gene in Fenneropenaeus chinensis (Fc-vasa-like) is presented. The origin and migration of the germ cell are revealed by whole mount in situ hybridization (ISH). Furthermore, gonadogenesis is observed by histological techniques and ISH. Fc-vasa-like mRNA is located in the cytoplasm of oocytes before and after spawning, and equally distributed in the cytoplasm of early embryos, from the 2-cell embryo to the blastula, indicating that Fc-vasa-like mRNA is maternally supplied. Later on, the expression of the Fc-vasa-like gene centralizes gradually, and is restricted to five cell clusters as precursor cells of primordial germ cells (PGCs) at the limb bud stage. The five cell clusters are located at the base of the antennules and antenna, as well as the cephalic lobe, implying an epigenetic mechanism of germ cell specification in this species. These cells migrate to a dorsolateral position in naupliar and zoeal stages, and gradually enter the genital ridge at the mysis 1 stage. The gonad is first detected histologically at the post-larval 1 stage (PL1, 1st day postlarva), and germ stem cells (GSCs) are distinguished in cluster in juveniles with the body length of 30mm. Our findings show that the developmental expression pattern of Fc-vasa-like is different from that of other Crustaceans, and suggest an epigenetic mechanism of germ cell development in Chinese shrimp. [Copyright &y& Elsevier]

Abstract: Hemocyte of shrimp as an important target cell for white spot syndrome virus (WSSV) was an optimal target for the investigation of interactions between WSSV structural proteins and host cells. In this study, hemocyte membrane of Fenneropenaeus chinensis (HmFc) was prepared and labeled with digoxigenin (DIG), then used as a probe to detect the HmFc-binding proteins in WSSV structural proteins by modified virus overlay protein binding assay (VOPBA) technique. A prominent immunoreactive protein band was identified in WSSV structural proteins, which was corresponding to VP 26. Subsequently, in order to investigate the VP26-binding protein in HmFc, VP26 was expressed, purified and labeled with fluorescein isothiocyanate (FITC). Detected by indirect immune fluorescence assay (IIFA), FITC-labeled recombinant VP26 (rVP26) showed binding ability to the shrimp hemocytes. Furthermore, result of VOPBA demonstrated that rVP26 could specifically recognize a protein in HmFc with an apparent molecular weight of 42kDa, which was identified to be β-actin by mass spectrometric analysis. These results indicate that the interaction between VP26 and β-actin might play an important role in WSSV infection. [Copyright &y& Elsevier]

Abstract: White spot syndrome virus (WSSV) is the most serious disease threatening the shrimp farming. Previous studies have elucidated the relationships between WSSV outbreak and environmental factors such as temperature, salinity and pH. But, these studies didn''t expatiate the relationships between the copy numbers of WSSV replication and the changes of environmental factors, even educed some contrary conclusions. Here, by the methods of Taguchi and real time PCR, the impact of three factors, temperature, salinity and pH on the proliferation of WSSV was studied together. The five levels selected for three factors were 15°C, 20°C, 25°C, 30°C and 35°C for temperature, 15‰, 20‰, 25‰, 30‰ and 35‰ for salinity and 6.5, 7.5, 8.0, 8.5 and 9.0 for pH. ANOVA analysis showed that significant differences existed between 15°C and 25°C (P=0.044), between 20°C and 25°C (P=0.047), and between 35°C and 25°C (P=0.044) for temperature. No significant differences were found among the levels of salinity and pH. This discovered that, of the three factors, the temperature was a crucial factor in determining WSSV proliferation. Hyperthermia (35°C) and hypothermia (15°C) could significantly decrease the WSSV proliferation while 25°C was the optimum temperature of WSSV replication. Moreover, low temperature was a more efficient factor to control WSSV replication and mortality of individuals infected WSSV, because the copy numbers of WSSV were only 0.626 per ng muscle at 15°C, while there were 5.94 copies at 35°C. Our study showed that the optimal WSSV proliferation condition was 30°C for temperature, 35‰ for salinity, and 8.0 for pH, and reversely, the worst WSSV proliferation condition was 15°C for temperature, 35‰ for salinity, and 9.0 for pH. [Copyright &y& Elsevier]

Abstract: In the present study, a highly sensitive and specific TaqMan real-time PCR was developed to quantify white spot syndrome virus (WSSV) infections in wild broodstock and hatchery-reared postlarvae of fleshy shrimp, Fenneropenaeus chinensis. A total of 159 individuals of wild F. chinensis brooders from 3 locations were captured and 210 postlarvae (PL1–8) were obtained from seven commercial hatcheries in 2007 in South Korea. The WSSV infections in 3 broodstocks showed a wide range, from 0 to 2.28×106 (with a mean of 1.50×104) copies ng−1 of DNA. Out of 159 brooders assayed, 39 (24.5%) were negative and 120 (75.5%) were positive; 153 (96.2%) showed less than 100 copies (mean 10.2 copies), 111 (69.8%) showed less than 10 copies and only 6 individuals (3.8%) showed high infections with a range of 2.36×102 to 2.28×106 copies ng−1 of DNA. In 210 postlarvae, a range of 2.6 to 713.6 (with a mean of 220) copies g−1 of DNA was observed. The mean WSSV copy number in the postlarvae was 7.9×105, which was equivalent to 8.5×105 copies mg−1 of postlarvae weight. A total of 87.1% of postlarvae were WSSV positive and except for two hatcheries (H4 and H7), the postlarvae of all the other five hatcheries were positive. Even postlarvae from the same hatchery, especially of hatcheries H4 and H5, showed a wide range of WSSV infection resulting in higher infections than other hatcheries. There were 34.3% of the postlarvae assayed in the present study that showed very low infection, with less than 10 copies ng−1 of DNA. Based on our results, it is recommended to pre-screen broodstock or larvae for selective breeding, stocking in production systems or stock enhancement. [Copyright &y& Elsevier]

Abstract: With their inherent immune system, shrimps survive in marine environments despite the presence of different stressors, such as bacteria, fungi, and virus. In order to fight against and subsist even in the presence of such pathogens, the shrimps'' ability to produce and release antimicrobial peptides are indeed important. In view of this, a new type of genetic material, an antimicrobial peptide containing a single whey acidic protein domain (SWD), was cloned from the haemocytes of fleshy prawns (Fenneropenaeus chinensis). Hence, this peptide is named Fc-SWD. The full-length cDNA of Fc-SWD was 399 bp, and it contained a single open reading frame (ORF) of 273 bp encoding an Fc-SWD of 90 amino acids, including a putative 24-amino acid signal peptide and a mature 66 residue peptide. Sequence comparison and phylogenetic analysis of SWDs and other whey acidic protein (WAP) domains containing proteins in crustaceans suggested that the crustacean WAP containing proteins can be divided into four classes: crustin I, crustin II, SWD, and carcinin and carcinin-like proteins. Apparently, the Fc-SWD is a new type in the SWD subgroup. Northern blot analysis demonstrated that Fc-SWD transcripts were constitutively expressed in the haemocytes of non-infected shrimps and increased in the haemocytes of infected shrimps. Meanwhile, Fc-SWD mRNA was not detected in the hearts, hepatopancreas, stomachs, gills, intestines, or ovaries of the non-infected shrimps nor the infected ones. Reverse transcription polymerase chain reaction (RT-PCR) experiments showed that the Fc-SWD signal was detected in the haemocytes, hearts, and gills of both the unchallenged and the challenged shrimps, and in the stomach of the challenged shrimps. Western blot analysis indicated that the Fc-SWD protein appeared to be synthesized in the haemocytes with a signal peptide and then secreted to the haemolymph as a mature peptide when the F. chinensis was infected by pathogens. Thus, the Fc-SWD (for the full-length peptide including the signal peptide), the mFc-SWD (for the mature peptide), and the Fc-WAPD (for the single WAP domain) were manifested in the Escherichia coli, respectively. Further findings indicated that the purified recombinant Fc-SWD and the mFc-SWD have antimicrobial activities against Gram-positive (G+) and Gram-negative (G−) bacteria and fungi, as well as a strong inhibitory activity against subtilisin A and protein K. The Fc-WAPD has anti-protease activities and low antimicrobial activity. In view of the foregoing findings, it can be concluded that Fc-SWD is one of the factors that affect shrimps'' immunity against various pathogens. [Copyright &y& Elsevier]

Abstract: Crustacean haemocytes play important roles in the host immune response including recognition, phagocytosis, melanization, cytotoxicity and inter-cellular signal communication. Expressed sequence tags (ESTs) analysis is proved to be an efficient approach not only for gene discovery, but also for gene expression profiles performance. In order to further understand the innate immune system and defense mechanisms of Chinese shrimp at molecular level, complementary DNA library is constructed from the haemocyte tissue of Fenneropenaeus chinensis. A total of 2371 cDNA clones are successfully sequenced and the average sequence length is 460 bp. About 50% are identified as orthologs of known genes from other organisms by BLASTx and BLASTn program. By sequences comparability and analysis, 34 important genes including 177 ESTs are identified that may be involved in defense or immune functions in shrimp based on the known knowledge. These genes are categorized into five categories according to their putative functions in shrimp immune system: 13 genes are different types of antimicrobial peptides (AMP, penaeidin, anti-lipopolysaccharide factor, etc.), and their proportion is about 38%; 11 genes belong to prophenoloxidase system (prophenoloxidase, serine proteinase, serine proteinase inhibitor, etc.), and their proportion is about 32%; five genes have high homology with clotting protein (lectin, transglutaminase, etc), and their proportion is about 15%; three genes may be involved in inter-cell signal communication (peroxinectin, integrin), and their proportion is about 9%; two genes have been identified to be chaperone proteins (Hsc70, thioredoxin peroxidase), and their proportion is about 6%. These EST sequences enrich our understanding of the immune genes of F. chinensis and will help further experimental research into immune factors and improve our knowledge of the immune mechanisms of shrimp. [Copyright &y& Elsevier]

Abstract: The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus–phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus–phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47±15.44%) was higher than that in the control treatment (34.67±15.11%), there was no significant difference in the mortality between them (P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested. [Copyright &y& Elsevier]

Abstract: This study was initiated to assess the feasibility of parentage determination in aquaculture populations for Chinese shrimp (Fenneropenaeus chinensis). Under different scenarios both simulation and real, we used microsatellite markers to assign parentage to offspring. Simulations based on allele frequency data from the population of Chinese shrimp demonstrated that 4 loci were required to assign 95% and 5 loci to assign 97% of progeny. When marker data from five loci were combined, the assignment success of progeny to their true parental couple increased to 92.9% in parentage identification with known parental and filial information. Out of 215 offspring, 90.7% was assigned to their parental pairs exclusively in mixed families groups. Discrepancies between the simulations and real data sets were considered to be largely due to the mismatches caused by scoring errors at microsatellite loci. Based on these results, we conclude that the use of a number of microsatellite markers represents a realistic and effective alternative to physical tagging in a selection program and it allows the identification of parental effects on offspring performances from early life stages. [Copyright &y& Elsevier]

Abstract: Seven AFLP primer sets were used to investigate the genetic structure of a wild base population and three generations of marine shrimp Fenneropenaeus chinensis selected for fast growth (F5–F7). More than 500 bands were generated in total. On average, each primer set detected 33.7 polymorphic markers. The expected average heterozygosity ranged from 0.085 to 0.097. As time under selection increased, genetic diversity tended to reduce, the differentiation between generations became less, and the variation of genetic structure of the populations became smaller. [Copyright &y& Elsevier]

Abstract: The effects of dissolved oxygen (DO) concentration and stocking density on growth performance, such as growth, survival, ecdysis, oxygen consumption, ingestion and food conversion efficiency (FCE), and non-specific immunity factors, such as phenoloxidase (PO), superoxide dismutase (SOD), peroxidase (POD), antibacterial activity (Ua), lysozyme (Ul) were investigated in the Chinese shrimp Fenneropenaeus chinensis. Shrimp growth (gain in length and weight), survival rate, ecdysis, ingestion and FCE were not significantly different among DO concentration treatments. The activities of SOD, POD, Ua, Ul and hemolysin were significantly affected by DO concentration. Mean oxygen consumption was significantly higher under high DO concentration (HDO) compared with medium (MDO) and low DO concentrations (LDO). Shrimp growth (gain in length and weight), survival rate, FCE and the activity of PO enzyme decreased, whereas ingestion and the activity of POD enzyme increased with increasing stocking density. The activity of hemolysin was significantly higher in high stocking density (HSD) compared with medium (MSD) and low stocking density (LSD). There was an interactive effect of DO concentration and stocking density on shrimp weight gain, ecdysis, O2 consumption, ingestion, the activities of Ua and hemolysin. The results revealed that DO concentration was one of the key factors which affecting shrimp through influencing activities of non-specific immunity factors (SOD, POD, Ua, Ul and hemolysin), while stocking density affected the growth performance of shrimp mainly by influencing ingestion or activities of enzymes (PO, POD and hemolysin), and the interactive effects of DO concentration and stocking density (P <0.05) played a crucial role in the production of shrimp farming. [Copyright &y& Elsevier]

Abstract: In order to observe the effect of salinity on disease resistance and white spot syndrome virus (WSSV) proliferation in Fenneropenaeus chinensis, shrimps with latent WSSV were subjected to two acute salinity changes from the original salinity of 22 ppt to 18 and 14 ppt in an hour, respectively. The total haemocyte count (THC) of the challenged group showed no evident change under salinity adjustments, but the phenoloxidase (PO) index declined significantly (P <0.05) corresponding to continuing acute salinity changes from the 24th to the 72nd hour. According to the WSSV load detected by quantitative real-time PCR method, it was found that WSSV carried by the challenged group and control group were significantly different (P <0.05); acute salinity change from 22 to 14 ppt led to the WSSV carried in the challenged group being significantly higher (P <0.05) than that of those surviving in 22 ppt, but salinity change from 22 to 18 ppt had no such effect. At the end of the 72-h experiment, the challenged group subjected to salinity change from 22 to 14 ppt had nearly 3 times the WSSV load as the control group with no salinity change. Therefore, salinity changes over a particular range could result in a decrease of immunocompetence and obvious WSSV proliferation in the shrimps, leading to white spot syndrome developing from a latent infection to an acute outbreak. [Copyright &y& Elsevier]

Abstract: The Oceanic Institute (OI), in collaboration with researchers from the University of Arizona (UAZ), established a population of specific pathogen free (SPF) Fenneropenaeus chinensis through Secondary Quarantine (SQ) in Kona, Hawaii. Shrimp were 0.38 g (S.D.±0.13 g) when they entered the nursery/growout module of the SQ facility. Juveniles from five maternal families were stocked in separate 230-L nursery tanks, as was a sixth family comprised of shrimp from two of the seven original spawns. After tagging, representative shrimp from all six families were stocked in a 50-m2 concrete raceway that was enclosed in a biosecure greenhouse. After 155 days in the growout module, mean shrimp weight was 23.4 g (S.D.±7.25 g) and females (29.1±4.61 g) were 74% larger than males (16.7±2.44 g). A Sprung Structure™ was erected to enclose the biosecure maturation and hatchery module of the SQ facility. Broodstock were subjected to an acclimation process where they were kept in seawater at 22 °C, followed by a reduction in water temperature of 1 °C/day until the temperature reached 17 °C. At this time, unilateral eyestalk ablation was performed on female broodstock and water temperature was further reduced at the same rate until it reached 12 °C. After 2 weeks, water temperature was raised to 17 °C at a rate of 1 °C/day to induce ovarian development. Production of an F1 generation of Fe. chinensis was successfully accomplished using artificial insemination, and representative shrimp from this generation have tested negative for all specifically listed pathogens using histology and PCR/RT-PCR. Of particular interest with Fe. chinensis is their cold tolerance. This species may represent a valuable resource for shrimp farmers in temperate and sub-tropical climates to grow a second “winter” crop, thereby increasing production and profitability for the shrimp farmer. [Copyright &y& Elsevier]

Abstract: 229 SSRs (simple sequence repeats) were identified among 10,443 ESTs (expressed sequence tags) of Chinese shrimp (Fenneropenaeus chinensis). The average density of SSRs was one SSR per 19.1 kb of EST sequence screened. The dinucleotide repeats appeared to be the most abundant SSRs detected. Nine EST–SSR markers were detected polymorphisms of the thirty SSR primer pairs derived from F. chinensis ESTs. The number of alleles per locus ranged from 5 to 15, with an average of 9.1 alleles per locus. The observed heterozygosity of nine loci ranged from 0.47 to 0.87. These loci were used successfully for pedigree analysis in three families of Fenneropenaeus chinensis. Two of the nine microsatellite loci showed the existence of null alleles. Assuming the existence of null alleles at Fc07 and Fc14 loci, the allelic inheritance mode of the EST–SSR DNA markers (Fc04, Fc06, Fc07, Fc10, Fc14, Fc18, Fc22, Fc24, and Fc27) was consistent with Mendelian segregation. [Copyright &y& Elsevier]

The specific growth rate (SGRd) of juvenile Fenneropenaeus chinensis shrimp was measured over 35 days under different light intensities: 0, 50, 300, 1300 and 5500 lx. The SGRd of the shrimp under 5500 lx was only 29.4%, 27.1%, 21.1% and 19.7% of those under 0, 1300, 50 and 300 lx, respectively (P<0.05). The maximal and minimal feed intake (FId) of shrimp occurred under 300 and 5500 lx, respectively (difference 9.3%). The lowest food conversion efficiency (FCEd) occurred in the 5500 lx group (30.2%, 26.3%, 21.3% and 21.1% of those under 0 lx, 1300 lx, 50 lx and 300 lx, respectively). FCEd values between 5500 lx and other groups were significantly different (P<0.05). The shrimp under 5500 lx gained a lower FI as well as a lowest FCE and therefore exhibited a lower SGR. The results revealed that light intensity affected the growth of the shrimp mainly by influencing FCE, or energy allocation to growth. Therefore, the shrimp may grow better in organically rich earthen ponds that have lower light intensity. [Copyright &y& Elsevier]

The specific growth rate (SGR) over 45 days of Fenneropenaeus chinensis shrimp with initial body weight of 1.979±0.036 g under different light color was as follows: natural>green>yellow>blue light. The SGR of shrimp under blue light was only 73.0% and 85.8% of those under natural light and green light, respectively. The maximal and minimal feed intake (FI) of the animal occurred under blue light and yellow light (difference 16.6%), respectively. The lowest food conversion efficiency (FCE) occurred in the blue light group (64.5% and 75.8% of that under natural and green light, respectively). FCE values between blue and natural light groups were significantly different (P<0.05). F. chinensis was relatively sensitive to blue light, under which the animal was active in feeding behavior, and gained a higher FI as well as a lower FCE, and therefore, a lower SGR.Shrimp may grow faster in the organically rich earthen ponds than in organically poor waters because there is less blue light spectrum in earthen ponds. [Copyright &y& Elsevier]

Chromosome manipulation for commercially valuable marine animals plays an important role in aquaculture. The special reproductive characteristics of shrimp make it difficult to control fertilization and synchronize egg development, so research on chromosome manipulation in shrimp has proceeded very slowly. In the present study, triploid shrimp Fenneropenaeus chinensis were induced by heat shocks and the optimal-inducing condition was screened at different spawning temperatures. Level of triploid induction for each treatment was evaluated by flow cytometry at nauplius stage. The highest level of triploid induction reached to more than 90%. Starting time for each treatment was very crucial for triploid induction in shrimp. One optimal treatment condition for triploid induction was heat shock (29–32 °C), starting at 18–20 min for duration of 10 min. These conditions varied depending on the temperature at spawning. Triploid level at embryo stage and nauplius stage was not different, suggesting the same hatching rate between diploids and triploids. Heat shock is a very effective way to induce triploids in this species, and can be easily used on large scale without any harmful effect on the environment as compared with chemical treatment. [Copyright &y& Elsevier]

The effects of protein restriction in the diet with subsequent realimentation on growth responses of juvenile Chinese shrimp, Fenneropenaeus chinensis (initial mean wet weight 1.347 g), were investigated. The control group (Group C) was fed an adequate diet containing 44.6% crude protein and 18.5 kJ gross energy/g dry matter throughout the experiment. For treatment Groups T15 and T30, in the restriction phase (weeks 1–2) dietary crude protein contents were reduced to 15.0% and 29.3%, respectively, with constant energy supply, while in the realimentation phase (weeks 3–6) they were supplied with the same diet as the control group. Protein restriction led to significant decrease in specific growth rates and body weight of shrimp. However, when the shrimp were transferred from protein restriction to realimentation, they had significantly increased specific growth rates in terms of dry matter, protein and energy (SGRd, SGRp and SGRe) compared with the control shrimp. At the end of the experiment, the shrimp in Group T30 achieved complete growth compensation, while those in Group T15 were still significantly smaller than the controls. As dietary protein levels reduced, feed conversion efficiencies and apparent protein digestibility decreased, but feed intake and protein efficiency ratio increased. The shrimp responded to a change from protein restriction to realimentation by displaying improved feed conversion efficiencies (FCEd, FCEp and FCEe) compared with the controls, although those in Group T15 delayed in showing the enhanced FCE values. In the initial 2-week realimentation, the shrimp in Group T15 showed significantly higher feed intake, and lower apparent digestibility of dry matter and protein than those of the controls. There was no significant difference in protein efficiency ratio among all groups in the realimentation phase. The above results suggest that compensatory growth in Group T30 is mainly dependent on improved feed conversion efficiencies, while that in Group T15 is attributable to both improved feed conversion efficiencies and increasing feed intake. After 2-week restriction, the shrimp showed lower body crude protein, lipid and energy content, and higher moisture and ash content than the controls. However, during the course of realimentation, the differences between the previously protein restricted shrimp and the controls diminished. This indicates that compensatory growth after a period of protein restriction in juvenile Chinese shrimp was accompanied by a complete recovery in body composition and energy content. [Copyright &y& Elsevier]

An emergent shrimp disease, acute hepatopancreatic necrosis disease (AHPND), has been causing great economic losses to the shrimp farming industry. The original causing agent of AHPND was regarded as Vibrio parahaemolyticus , with a plasmid named pVA1 carrying two Photorhabdus insect-related (Pir) toxin genes pir A and pir B. In the present study, a Vibrio owensii strain named FcYS03 was isolated from the Chinese shrimp Fenneropenaeus chinensis , which caused a high mortality in shrimp with typical AHPND signs. This strain carried the binary toxin genes pir AB and could cause AHPND both in Fenneropenaeus chinensis and Penaeus vannamei (previously named Litopenaeus vannamei). The pathogenicity of FcYS03 to P. vannamei exhibited apparent temperature and salinity dependence. Through genome sequence analysis among FcYS03 and AHPND-causing V. parahaemolyticus strain 3HP, we found that a segmental rearrangement phenomenon existed in the plasmid of FcYS03. The toxin genes pir AB happened to be located at the rearranged segment, and two transposases for transposon Tn903 were distributed at the two ends of the rearranged segment, which indicated that transposon Tn903 might be related to the transfer of the toxin genes among the bacteria. The study will provide valuable information for the understanding and prevention of AHPND in shrimp aquaculture. • A strain of Vibrio owensii (FcYS03) causing AHPND was isolated from Fenneropenaeus chinensis. • Its pathogencity to shrimp is water temperature and salinity dependent. • A segmental rearrangement existed in the plasmid of FcYS03 compared with the known plasmid pVA1 in V. parahemolyticus 3HP. [ABSTRACT FROM AUTHOR]

Ras is a small GTP-binding protein that is involved in the regulation of diverse cellular processes, including cell cycle progression, proliferation, and apoptosis. In the present study, a cDNA encoding Ras protein in Chinese shrimp Fenneropenaeus chinensis (designated FcRas) was cloned. The cDNA of FcRas contained a 564 bp open reading frame (ORF), five conserved regions involved in GTP metabolism, and a CAAX motif. Multiple sequence alignment showed that the C-terminal of Ras was less conserved than the N-terminal. In healthy F. chinensis , the FcRas mRNA level in the hepatopancreas and gill were both significantly (P < 0.05) higher than the level in muscle. Following challenge with white spot syndrome virus (WSSV), the FcRas mRNA level in the muscle was significantly (P < 0.05) upregulated at 48 h post-infection (hpi). In the hepatopancreas, the FcRas mRNA level was significantly downregulated at 12 hpi (P < 0.01) and 24 hpi (P < 0.05). The protein level of FcRas in the hepatopancreas was significantly downregulated at 6, 12, 24, and 48 hpi (P < 0.05). These results suggested that the FcRas expression level was influenced by WSSV infection. • A cDNA encoding Ras from Fenneropenaeus chinensis (FcRas) was cloned and sequenced for the first time. • The FcRas mRNA level in the hepatopancreas and muscle changed post white spot syndrome virus challenge. • The FcRas protein level in the hepatopancreas was down-regulated post white spot syndrome virus challenge. [ABSTRACT FROM AUTHOR]