Fenneropenaeus Chinensis Research Articles

Effects on survival time of Fenneropenaeus chinensis challenged by different doses of WSSV and diets

White spot syndrome virus(WSSV)is one kind of destructive virus affecting shrimp industry in the world.Output of Fenneropenaeus chinensis which once was a staple species has been greatly affected by outbreak of WSSV since 1993 in China.To produce WSSV-resistance shrimp strains is an important approach to revive the shrimp industry.To select survived F.chinensis as broodstock via WSSV challenge test can increase the efficiency of breeding.However,mortality of shrimps could reach nearly 100% once they were infected with WSSV,which increases the difficulty for shrimp breeding.In this study for the purpose to reveal effect of different WSSV amount on F.chinensis,juvenile F.chinensis were infected with a certain amount of WSSV individually and the survival time and survival rate were observed.The results showed that survival time of shrimps infected with 5.2×108 copies,1.0×109 copies and 2.1×109 copies of WSSV respectively was 389.3,323.3 and 187.3 h and significant different(P0.01).The cumulative mortalities of all the shrimps finally reached 100%.The survival time increased while shrimps were fed with less WSSV bait.For the purpose to reveal the effect of diets on the ability for disease resistance,shrimps infected with WSSV were fed with different diets of live brine shrimps,commercial bait and fresh clam.It was showed that the survival time of infected shrimps fed with live brine shrimps,fresh clam and commercial bait respectively was 281.7,173.9 and 164.9 h.The survival time of infected shrimp fed with live brine shrimps was significantly higher than that fed by commercial bait and fresh clam respectively(P0.01).There was no significant difference of survival time between infected shrimps fed with commercial bait and fresh clam(P0.05).Cumulative mortalities of all the groups of infected shrimps that fed with different diets were 100%.Live brine shrimp is better than commercial bait and fresh clam for the purpose of enhancing shrimp WSSV resistance ability.

An IκB homologue (FcCactus) in Chinese shrimp Fenneropenaeus chinensis

This study firstly reports the characterization of a functional IκB homologue, FcCactus in Chinese shrimp Fenneropenaeus chinensis. The full length cDNA of FcCactus consists of a 1359bp open reading frame (ORF) encoding a 453 amino acid protein with a predicted molecular weight (MW) of 48.46kDa and theoretical pI of 5.23. Phylogenetic analysis and multiple alignments revealed that the deduced amino acid sequence of FcCactus cDNA had high similarities to Cactus or IκB reported in seven other arthropods. Genomic DNA sequence of FcCactus was also obtained with a length of more than 17698bp and constituted of seven exons and six introns. Analysis on 5′-upstream regulatory region of its DNA sequence revealed that it contained the core promoter sequence with the TATA-box and transcription start site existing in it; furthermore, various transcription factor binding sites (HSF, Hb, BR-C Z, Dfd, CF2-II, Croc, Ttk, Dorsal, and c-Rel) were predicted. Spatial expression profiles showed that FcCactus mRNA had the highest expression level in muscle, hemocytes, heart and lymphoid organ. Gram-positive bacteria (Micrococcus lysodeikticus) and Gram-negative bacteria (Vibrio anguillarium) injection to shrimp caused the modulation of FcCactus at the transcription level. DsRNAi (double-strand RNA interference) approach was used to study the function of FcCactus and the data showed that FcCactus could regulate the expression of different antimicrobial peptides (AMPs) and antiviral factor (AV). The present data showed that FcCactus might play important roles in regulating the immune response of shrimp.

Shrimp MyD88 responsive to bacteria and white spot syndrome virus

The myeloid differentiation factor 88 (MyD88) is an important adapter protein which links members of the toll-like receptor (TLR) to the downstream components to activate related signaling pathways. In the present study, a MyD88 homolog (FcMyD88) was cloned from penaeid shrimp Fenneropenaeus chinensis. The ORF of FcMyD88 consisted of 1434 bp encoding a polypeptide of 477 amino acids which contains a death domain (DD) and a typical TLR and interleukin-1 receptor (IL-1R)-related (TIR) domain. Homology analysis revealed that the predicted amino acid (aa) sequence of FcMyD88 shared high similarities with a variety of previously reported MyD88s. The time-dependent expression patterns of FcMyD88 in cephalothoraxes of shrimp injected with Vibrio anguillarum (Gram-negative bacteria, G−), Micrococcus lysodeikticu (Gram-positive bacteria, G+) and white syndrome spot virus (WSSV) were analyzed at transcription and protein level by real-time PCR and western blotting, respectively. The expression level of FcMyD88 mRNA was significantly up-regulated at one hour (h), 12 h and 24 h after stimulation with both V. anguillarum and M. lysodeikticu. The expression level of FcMyD88 protein was 2-fold up-regulated at 12 h post injection (hpi) of inactivated V. anguillarum while it didn't change after M. lysodeikticu injection during this period. After WSSV injection, the expression level of FcMyD88 mRNA remained relatively constant, while the FcMyD88 protein was significantly up-regulated at 12 and 24 hpi. These results suggested that the MyD88-dependent signaling pathway could be involved in the defense of both bacteria and WSSV infection.

Identification and molecular characterization of a C-type lectin-like protein from Chinese shrimp (Fenneropenaeus chinensis)

A C-type lectin-like protein was cloned and characterized from the Chinese shrimp Fenneropenaeus chinensis, and named as FcCTL. The results indicated that the full length cDNA of 859 bp had an open reading frame encoded a polypeptide of 220 amino acids with one carbohydrate-recognition domain, six conserved Cys and one key motif EPGD. The theoretical molecular weight and pI of mature protein was 25.3 kDa and 5.4. Sequence comparison of the deduced amino acid sequence of FcCTL showed varied identity of 26-34, 34, 31 and 30 % with those of F. chinensis, Portunus trituberculatus, Tetraodon nigroviridis, Penaeus monodon, respectively. qRT-PCR analysis indicated that FcCTL was expressed highest in hepatopancreas of normal shrimp, and it's expression was up-regulated in hepatopancreas and gills post white spot syndrome virus challenge. The purified recombinant FcCTL showed higher antimicrobial activity against Gram-positive bacteria than against Gram-negative bacteria and fungi. And the hemagglutinating activity of rFcCTL could be completely inhibited by GlcNAc (5 μg/ml), LPS (2.5 μg/ml), D-galactose (100 mM) and maltose (100 mM). These data suggested that FcCTL might play an important role in shrimp immune and would be helpful to better understand the innate immunity mechanism of shrimp.

New polymorphic microsatellite markers for Chinese shrimp (Fenneropenaeus chinensis) from sequence database

Chinese shrimp (Fenneropenaeus chinensis) is very popular in the world market. In this study, microsatellite markers were developed from expressed sequence tags (ESTs) of F. chinensis. Eighteen primer pairs were designed for EST sequences containing perfect motifs and the genomic DNA was extracted from 35 F. chinensis individuals. Thirteen high polymorphic microsatellites were successfully amplified. The number of alleles ranged from 2 to 8 per locus. The observed and expected heterozygosity ranged from 0.0857–0.9143 to 0.1590–0.8373, respectively. No loci departed from Hardy–Weinberg equilibrium after adjusting using Bonferroni correction (P < 0.05). There was no LD observed between all pairs of EST-SSRs loci. These microsatellite markers provide useful tools for studies of population genetics of shrimp.

Analysis on the dynamic changes of the amount of WSSV in Chinese shrimp Fenneropenaeus chinensis during infection

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.

The primary culture and subculture of lymphoid cells from shrimp,Penaeus chinensison thermo-sensitive CS/α, β-GP hydrogel

A thermo-sensitive hydrogel composed of chitosan and α, β-glycerophosphate was successfully synthesized and used as basic substrate for primary culture and subculture of lymphoid cells from shrimp, Penaeus chinensis. When the ambient temperature increases from 4°C to 25°C, the chitosan/α, β-glycerophosphate solution transforms into a semi-solid three-dimensional hydrogel with a rough surface. Primary lymphoid cells formed were round and grew homogenously over the surface of the hydrogel. The peroxidase activity indicated that cells seeded on the hydrogel suffered less stress than cells suspended in control culture flasks. The higher relative viability and alkaline phosphatase activity of primary cultured lymphoid cells indicated that the chitosan/α, β-glycerophosphate hydrogel enhanced the growth and proliferation of lymphoid cells. Subsequent subculture of lymphoid cells starting from crumbled primary hydrogel culture was also successful.

Role of chymotrypsin-like serine proteinase in white spot syndrome virus infection in Fenneropenaeus chinensis

White spot syndrome virus (WSSV) caused a great economic loss in shrimp aquaculture. Although great efforts have been undertaken to characterize the virus disease during the last two decades, there are still lack of effective methods to prevent or cure it. In this study, we investigated the transcriptional expression profiles of 18 key immune-related genes in the Chinese shrimp Fenneropenaeus chinensis which was severely infected by WSSV. We found that the expression levels of 6 genes including chymotrypsin-like serine proteinase (CH-SPase), heat shock protein 70 cognate (HSP70), penaeidin (PEN), peroxinectin (PO), proliferating cell nuclear antigen (PCNA) and argonaute (AGO) changed significantly, while the expression of the other 12 genes had no significant changes compared to the control group. Among the 6 screened genes, CH-SPase showed significantly up-regulation, while the other 5 ones were significantly down-regulated. Knockdown of the expression of CH-SPase in WSSV-infected Chinese shrimp reduced the copy number of WSSV and delayed cumulative mortalities, suggesting that CH-SPase is important for WSSV infection. This study will be helpful to control the disease in shrimp caused by WSSV.

Long-term changes in the fishery ecosystem structure of Laizhou Bay, China

Laizhou Bay provides a critical spawning and nursery habitat for many fishery species, including commercially important species, such as Fenneropenaeus chinensis and Larimichthys polyactis. The bay is severely stressed due to high fishing pressure and environmental changes. Based on the long-term ecosystem surveys in Laizhou Bay during the main spawning period (May) of most fishery species from 1959 to 2008, the responses of the Laizhou Bay fishery ecosystem were analyzed here, including regime shifts in species composition, biomass, species diversity, zooplankton, phytoplankton, and environmental variables. The dominant species of large-size and high economic value (e.g. Trichiurus haumela, L. polyactis) have been replaced by the short-lived, low-trophic-level planktivorous pelagic species (e.g. Setipinna taty, Engraulis japonicus) since the 1980s, and it is probable that the small-sized pelagic fishes have been recently replaced by invertebrates (e.g. Oratosquilla oratoria, Crangon affinis). The biomass of fishery resources declined continuously from 423.6 kg haul−1 h−1 in 1959 to 164.6 kg haul−1 h−1 in 1982, 37.7 kg haul−1 h−1 in 1993, and less than 8 kg haul−1 h−1 in 1998–2008. Moreover, the biomass of zooplankton showed an increasing trend during 1959–2006, but showed a slight decline in 2008. The abundance of phytoplankton increased from 1959 through 1982, decreased substantially in 1993, and increased again until 2004. More recently, however, the phytoplankton abundance was very low. The sea surface temperature (SST) and sea bottom temperature (SBT) in May increased by 0.23°C a−1 and 0.16°C a−1, respectively, during 1982–2008. The salinity in May showed large fluctuations and reached its lowest values in 2004 and 2006. The ratio of dissolved inorganic nitrogen (DIN) to dissolved inorganic phosphate (DIP) increased. However, the dissolved silicon (DSi):DIP and DSi:DIN ratios decreased to a low level during 1959–2008. These changes seriously impacted primary production, and cascade effects then changed the structure and function of the fishery ecosystem. Further analysis indicated that multiple stresses caused the alterations in the structure of the Laizhou Bay fishery ecosystem. The top-down effect was identified as the main influence on the fishery species (at the top of the food chain) over the past five decades due to the increasing fishing pressure, whereas the bottom-up effect increased over the past three decades due to the strong variations in the environment.

Development of a multiplex PCR system for the simultaneous detection of white spot syndrome virus and hepatopancreatic parvovirus infection

A multiplex PCR kit for simultaneous detection of white spot syndrome virus (WSSV) and hepatopancreatic parvovirus (HPV) was developed and field testing was conducted. A 604-bp target sequence was selected from the vp28 gene of WSSV. A primer set was developed to amplify a 338-bp DNA fragment at the junction of the NS2 and NS1 protein genes of HPV after alignment of eight sequences from different strains. Another internal positive control primer set produced a 139-bp PCR fragment from the β-actin gene by alignment of this gene from Litopenaeus vannamei, Fenneropenaeus chinensis and Penaeus monodon. The detection limits, tested using purified plasmids, for WSSV and HPV were 21.4 and 19.0 copies respectively. The optimum ratio for HPV, WSSV and β-actin was 3:1:1, with an optimum annealing temperature of 57°C. Field test of the multiplex PCR with 170 L. vannamei individuals from 17 aquaculture farms showed 41.8% coinfection with WSSV and HPV, and 40.0% and 3.5% single infection with WSSV and HPV respectively. No virus-free shrimp farm was found. Ten wild catch F. chinensis individuals showed 60% coinfection, and 40% were infected with HPV.

A trehalose-6-phosphate synthase gene from Chinese shrimp, Fenneropenaeus chinensis

Trehalose is an important disaccharide and plays a key role in many organisms under different stress conditions. In the study, a gene (FcTPS) encoded trehalose-6-phosphate synthase was reported from Chinese shrimp, Fenneropenaeus chinensis. The full-length cDNA of FcTPS is 3,281 bp including a poly A-tail of 20 bp, encoding a putative protein of 844 amino acids. The predicted protein contains a glycol_transf_20 domain and a trehalose_PPase domain. Genomic structure of FcTPS is composed of three exons with 192, 157 and 2,912 bp and two introns with 1,057 and 568 bp. In the second intron, four different SSRs are found. Transcripts of FcTPS gene are constitutively expressed in various tissues, with strongest level in hepatopancreas. After the shrimp were challenged with WSSV or Vibrio and the expression of FcTPS in hepatopancreas were analyzed using real-time PCR, the result showed that FcTPS transcript was down-regulated significantly in response to the challenge of Vibro at the early of 5 h post-challenge and then up-regulated significantly at 14 h. In addition, the expression of FcTPS showed the same result after the shrimp were challenged with WSSV. These results provide some new information about the tissue distribution, expression profiles and potential function of the trehalose-6-phosphate synthase in shrimp.

Involvement of Fenneropenaeus chinensis Cathepsin C in antiviral immunity

Cathepsin C (Cath C) is a lysosomal cysteine protease that belongs to the papain superfamily. Cath C is capable of activating many chymotrypsin-like serine proteases and is reported to be a central coordinator for the activation of many serine proteinases in immune and inflammatory cells. In this study, Cath C cDNA was cloned from Fenneropenaeus chinensis (Fc). The complete cDNA of Fc-Cath C in Chinese white shrimp was found to be 1445-base pairs (bp) long. It contained an open reading frame (ORF) 1356-bp long and encoded a 451-amino acid residue protein, including a 17-amino acid residue signal peptide. Real-time PCR analysis results indicated that Fc-Cath C was present in all the tissues detected and exhibited high level of transcription in the hepatopancreas. In hemocytes, hepatopancreas, gills and intestine, Fc-Cath C was upregulated after stimulation by the Vibrio anguillarum and the white spot syndrome viruses (WSSVs). Replication of the WSSV increased after the injection of Fc-Cath C antiserum or knockdown Cath C by RNA interference. These results implied that Cath C might play a crucial role in the antiviral immune response of shrimp.

An integrin β subunit of Chinese shrimp Fenneropenaeus chinensis involved in WSSV infection

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.

Identification and Characterization of the Sex-Determiner Transformer-2 Homologue in Chinese Shrimp, Fenneropenaeus chinensis

The transformer-2 gene, encoding a protein (Tra-2) which directs sex-specifically alternative splicing of doublesex (dsx) pre-mRNA in combination with the transformer (Tra) protein, has been proved to play important roles on sex differentiation and sex development in Drosophila melanogaster. In the present study, a tra-2 homologue (FcTra-2) was cloned and characterized in the Chinese shrimp, Fenneropenaeus chinensis. A FcTra-2 genomic DNA sequence with a length of 8,871 bp was obtained and verified to consist of 7 exons and 6 introns. Three alternatively spliced mRNA transcripts, designated as FcTra-2a, FcTra-2b and FcTra-2c, were isolated and characterized. Sequence analysis showed that FcTra-2 included a RNA recognition motif and a linker region, which shared high sequence identities with Tra-2 from other species and 2 arginine/serine rich regions. Further studies were performed on the isoform FcTra-2c, since it exhibited a significantly higher expression level in ovary than in other tissues. In early developmental stages of the shrimp, FcTra-2c was detected to suddenly increase its expression level at the mysis stage. In juvenile stage, FcTra-2c displayed a significantly higher expression level in female Chinese shrimp than in males. These data indicated that FcTra-2 might be involved in female sex determination in Chinese shrimp.

Molecular cloning of prophenoloxidase and the effects of dietary β-glucan and rutin on immune response in hemocytes of the fleshy shrimp, Fenneropenaeus chinensis

To investigate the effects of dietary β-glucan (0.5 or 1 g kg−1 diet: 0.5-BG, 1-BG) and rutin (0.5 or 1 g kg−1 diet: 0.5-RT, 1-RT) after 10 days in the absence of pathogen challenge on the immune response of Fenneropenaeus chinensis, we determined total hemocyte count (THC) and the expression of four immune-related genes in hemocytes: those for prophenoloxidase (proPO), peroxinectin (PX), lipopolysaccharide and/or β-glucan binding protein (LGBP), and c-type lectin (CL). As a prerequisite for subsequent experiments, cDNA encoding proPO of the fleshy shrimp, Fenneropenaeus chinensis (f-proPO) was obtained from hemocytes; it had a full length of 3023bp, with an open reading frame (ORF) of 2061bp, a 105-bp 5′-untranslated region, and a 906-bp 3′-untranslated region containing the poly A signal. The THCs of shrimp fed β-glucan of 1 g kg−1 diet, and rutin of 1 g kg−1 diet were significantly higher than that of the control (P < 0.05). The expression of proPO mRNA was slightly downregulated and that of LGBP mRNA was upregulated (except in 1-RT). PX and CL mRNA remained constitutively expressed in all groups. Our results reveal that β-glucan and rutin dietary supplements have minimal effect on immune response in the absence of pathogen challenge.

Expression profiles of antimicrobial peptides (AMPs) and their regulation by Relish

Antimicrobial peptides (AMPs), as key immune effectors, play important roles in the innate immune system of invertebrates. Different types of AMPs, including Penaeidin, Crustin, ALF (antilipopolysaccharide factor) have been identified in different penaeid shrimp; however, systematic analyses on the function of different AMPs in shrimp responsive to different types of bacteria are very limited. In this study, we analyzed the expression profiles of AMPs in the Chinese shrimps, Fenneropenaeus chinensis, simultaneously by real-time RT-PCR (reverse transcription-polymerase chain reaction) when shrimp were challenged with Micrococcus lysodeikticus (Gram-positive, G+) or Vibrio anguillarium (Gram-negative, G−). Different AMPs showed different expression profiles when shrimp were injected with one type of bacterium, and one AMP also showed different expression profiles when shrimp were challenged with different bacteria. Furthermore, the expression of these AMPs showed temporal expression profiles, suggesting that different AMPs function coordinately in bacteria-infected shrimp. An RNA interference approach was used to study the function of the Relish transcription factor in regulating the transcription of different AMPs. The current study showed that Relish could regulate the transcription of different AMPs in shrimp. Differential expression profiles of AMPs in shrimp injected with different types of bacteria indicated that a complicated antimicrobial response network existed in shrimp. These data contribute to our understanding of immunity in shrimp and may provide a strategy for the control of disease in shrimp.

CDNA cloning and expression profile analysis of an ATP-binding cassette transporter in the hepatopancreas and intestine of shrimp Fenneropenaeus chinensis

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.

신규 살조제 Thiazolidinedione 유도체 (TD49)의 해양생물에 대한 생물 농축도 조사

In this study, a newly synthesized thiazolidinedione derivative, TD49 with a highly selective algicide to red tide, was examined in order to evaluate the bioconcentration on aquatic organisms of coast. BAF (accumulation of TD49 by aquatic food chain) and BCF (accumulation of TD49 by sea water) were examined employing the shrimp (Fenneropenaeus chinensis) as the feed organism, and the olive flounder Paralichthys olivaceus as a consumer in marine ecosystem. Bioconcentration degree in sea water showed that the order in P. olivaceus was viscera > gill > muscle. The average BCF values of TD49 were 67.70, 63.32 and 20.25 at viscera, gill and muscle, respectively. Bioaccumulation degree using feed showed that the order in the organs of P. olivaceus was viscera > gill > muscle. The average BAF values of TD49 were 175.89, 114.88 and 32.59 at viscera, gill and muscle, respectively. When compared with two results, the accumulation by the food and water was higher than that by water. After the elimination experiment in sea water, the TD49 concentration was 2.81 nmole/g in the viscera and were not found in the gill and the muscle. More than 50% of the accumulated TD49 were eliminated from viscera in 7 days and all the accumulated TD49 were eliminated from gill and muscle in 7 days. On the other hand, the octanol/water partition coefficient (log Kow) was measured to be 3.66 and experimental BCF of this study was 67.7.

Two spliced variants of insulin-like androgenic gland hormone gene in the Chinese shrimp, Fenneropenaeus chinensis

More and more evidence indicates that the insulin-like androgenic gland hormone (IAG) plays an important role in male sexual differentiation in crustaceans. In the present study, two IAG isoforms (Fc-IAG1 and Fc-IAG2) were identified from the penaeid shrimp Fenneropenaeus chinensis. Sequence analysis of IAG gene (Fc-IAG) showed that Fc-IAG1 and Fc-IAG2 were generated by alternative splicing of Fc-IAG pre-mRNA, and they shared almost the same deduced amino acid sequence. Both of them were composed of signal peptide, B chain, C peptide and A chain. They both contained the six conserved cysteine residues and a putative N-linked glycosylated site like IAGs reported in other crustacean species. Tissue distribution and in situ hybridization analysis revealed that they had the highest expression level in the androgenic gland. The transcripts of Fc-IAG1 and Fc-IAG2 could also be detected in hepatopancreas and nerve cord of both sexes at a low expression level. Analysis on their temporal expression profiles showed that they expressed at all embryonic and post-larvae stages. The expression of Fc-IAG1 at different developmental stages displayed a low and stable manner, while the expression of Fc-IAG2 began to increase from post-larvae stages, which suggested that Fc-IAG2 might be involved in male sexual differentiation. In the 5′ flanking sequence of Fc-IAG, putative binding sites for transcription factors regulating transcription of hormone genes and genes related to sexual development were predicted, which provided us a primary understanding on the regulation mechanism of Fc-IAG gene. This is the first time to report the gene structure of IAG gene and distinct variants of IAG transcripts in crustaceans.

Structure of mitochondrial DNA control region of Fenneropenaeus chinensis and phylogenetic relationship among different populations

This paper deals with the structure of mitochondrial DNA control region of Fenneropenaeus chinensis. The termination-associated sequence (TAS), cTAS, CSB-D–CSB-F, and CSB-1 are detected in the species. The results indicate that the structures of these parts are similar to those of most marine organisms. Two conserved regions and many stable conserved boxes are found in the extended TAS area, central sequences blocks, and conserved sequences blocks (CSBs). This is the special character of F. chinensis. All the mtDNA control region sequences do not have CSB2 and CSB3 blocks, which is quite different from most vertebrates. In addition, the complete mtDNA control region sequences are used to analyze the phylogenetic relationships of F. chinensis. The phylogenetic trees show a lack of genetic structure among populations, which is similar to many previous studies.