Characterization of transforming growth factor beta regulator 1-like and association between its expression levels and growth of the giant tiger shrimp Penaeus monodon

Molecular markers that allow selection of juveniles and broodstock with improved growth performances are useful for the shrimp industry. Here, the full-length cDNA of transforming growth factor beta regulator 1-like (PmTbrg1-l) in the giant tiger shrimp Penaeus monodon was determined. It was 1184 bp in length and contained an open reading frame (ORF) of 975 bp corresponding to a deduced polypeptide of 324 amino acids. Successful RNA interference (RNAi) carried out using juveniles injected with PmTbrg1-l dsRNA revealed reduced levels of PmTbrg1-l and myostatin (PmMstm) in hemocytes when compared to shrimp injected with saline solution and GFP dsRNA (P < .05). Associations between single-strand conformational polymorphism (SSCP) patterns or single nucleotide polymorphism (SNP) patterns and growth-related parameters (average body weight and total length) were examined. Juveniles with pattern III (corresponding to A/A₉₁₈; N = 37) showed a trend for greater average body weight and total length than those with patterns II (G/G₉₁₈; N = 42) and IV (A/G₉₁₈; N = 75). The expression level of PmTbrg1-l in the hepatopancreas of females was significantly higher than that in males (P < .05) in two sample sets of three-month-old domesticated juveniles (N = 59 and 50; P < .05). Moreover, its expression level in large-size juveniles was significantly higher than that in medium-size and small-size juveniles in both groups of samples (P < .05). Results indicated that PmTbrg1-l is functionally related with growth of P. monodon.

Characterization, expression and localization of valosin-containing protein in ovaries of the giant tiger shrimp Penaeus monodon

Valosin-containing protein (VCP), a member of the ATPase-associated with diverse cellular activity (AAA) family, was identified from the giant tiger shrimp (Penaeus monodon). The full-length cDNA of the PmVCP mRNA consisted of 2,724 bp containing an ORF of 2,367 bp corresponding to a deduced polypeptide of 788 amino acids. The deduced PmVCP protein contained two putative Cdc48 domains (positions 17-103, E-value=2.00e-36 and 120-186, E-value=3.60e-11) and two putative AAA domains (positions 232-368, E-value=3.67e-24 and 505-644, E-value=3.73e-25). PmVCP mRNA expression in ovaries was greater than that in testes in both juveniles and broodstock. PmVCP was significantly up-regulated in stages II and IV ovaries in intact wild broodstock (P<0.05) but it was not differentially expressed during ovarian development in eyestalk-ablated broodstock (P>0.05). The expression level of PmVCP mRNA in ovaries of 14-month-old shrimp was not affected by progesterone injection (0.1μg/g body weight, P>0.05). In contrast, exogenous 5-HT administration (50μg/g body weight) resulted in an increase of PmVCP mRNA in ovaries of 18-month-old shrimp at 6 and 24h post-injection (hpi) (P<0.05). The rPmCdc48-VCP protein and its polyclonal antibody were successfully produced. Cellular localization revealed that PmVCP was localized in the ooplasm of previtellogenic oocytes. Subsequently, it was translocated into the germinal vesicle of vitellogenic oocytes. Interestingly, PmVCP was found in nucleo-cytoplasmic compartments, in the cytoskeletal architecture and in the plasma membrane of mature oocytes in both intact and eyestalk-ablated broodstock.

Identification of reproduction-related proteins and characterization of proteasome alpha 3 and proteasome beta 6 cDNAs in testes of the giant tiger shrimp Penaeus monodon

Cellular proteomic analysis was carried out to identify reproduction-related proteins in testes of wild and domesticated broodstock of Penaeus monodon. In total, 642 protein spots were characterized and 287 spots (44.70%) significantly matched protein sequences in the databases (P<0.05). To examine a role of the proteasome system in testicular development of P. monodon, the expression profiles of proteasome alpha 3 subunit (PmPsma3) and proteasome beta 6 (PmPsmb6) mRNA in different groups of domesticated shrimp and in wild broodstock were examined. The expression levels of these transcripts in testes of 18-month-old domesticated shrimp were significantly lower than those of wild broodstock (P<0.05). Interestingly, the expression levels of testicular PmPsma3 and PmPsmb6 in 18-month-old shrimp were significantly increased at 24 h following serotonin injection (50 μg/g body weight). Results suggested that reduced degrees of maturation in captive P. monodon males may be partially resolved by exogenous 5-HT administration.

Identification of reproduction-related proteins and characterization of the protein disulfide isomerase A6 cDNA in ovaries of the giant tiger shrimp Penaeus monodon

Proteomic analysis was carried out for identification of proteins functionally involved in ovarian development of the giant tiger shrimp (Penaeus monodon). A total of 335 protein spots including 183 spots from vitellogenic (stage II) and 152 spots from mature (stage IV) ovaries of intact P. monodon broodstock were examined. Of these, 75 (40.98%) and 59 (38.82%) spots significantly matched known proteins in the databases, respectively. In addition, 270 protein spots including 167 and 103 spots from respective ovarian stages of eyestalk-ablated broodstock were also characterized. A total of 95 (56.89%) and 62 (60.19%) spots matched known proteins, respectively. Among differentially expressed reproduction-related proteins, the full-length cDNA of protein disulfide isomerase A6 (PmPDIA6) was further characterized by RACE-PCR. PmPDIA6 was 1946bp in length containing an open reading frame (ORF) of 1293bp corresponding to a polypeptide of 430 amino acids. PmPDIA6 was up-regulated at stage III ovaries in intact shrimp (P<0.05). Interestingly, eyestalk ablation resulted in a lower expression level of PmPDIA6 in each stage of ovarian development compared to that of intact broodstock (P<0.05). Results in this study clearly indicated the potential of cellular proteomic studies and gene expression analysis for identification of proteins/genes differentially expressed during ovarian development of P. monodon.

Isolation and characterization of genes functionally involved in ovarian development of the giant tiger shrimp Penaeus monodon by suppression subtractive hybridization (SSH)

Suppression subtractive hybridization (SSH) libraries between cDNA in stages I (previtellogenic) and III (cortical rod) ovaries of the giant tiger shrimp (Penaeus monodon) were established. In all, 452 ESTs were unidirectionally sequenced. Sequence assembly generated 28 contigs and 201 singletons, 109 of which (48.0%) corresponding to known sequences previously deposited in GenBank. Several reproduction-related transcripts were identified. The full-length cDNA of anaphase promoting complex subunit 11 (PmAPC11; 600 bp with an ORF of 255 bp corresponding to a polypeptide of 84 amino acids) and selenoprotein Mprecursor (PmSePM; 904 bp with an ORF of 396 bp corresponding to a polypeptide of 131 amino acids) were characterized and reported for the first time in penaeid shrimp. Semiquantitative RT-PCR revealed that the expression levels of PmSePM and keratinocyte-associated protein 2 significantly diminished throughout ovarian development, whereas Ser/Thrcheckpoint kinase 1 (Chk1), DNA replication licensing factor mcm2 and egalitarian were down-regulated in mature ovaries of wild P. monodon (p < 0.05). Accordingly, the expression profiles of PmSePM and keratinocyte-associated protein 2 could be used as biomarkers for evaluating the degree of reproductive maturation in domesticated P. monodon.

Molecular cloning and expression of progestin membrane receptor component 1 (Pgmrc1) of the giant tiger shrimp Penaeus monodon

Knowledge on molecular mechanisms of steroid hormonal induction on oocyte development may lead to the possible ways to effectively induce ovarian maturation in shrimp. In this study, progestin membrane receptor component 1 (Pgmrc1) of the giant tiger shrimp (Penaeus monodon) initially identified by EST analysis was further characterized. The full-length cDNA of Pgmrc1 was 2015bp in length containing an ORF of 573bp corresponding to a polypeptide of 190 amino acids. Northern blot analysis revealed a single form of Pgmrc1 in ovaries of P. monodon. Quantitative real-time PCR indicated that the expression level of Pgmrc1 mRNA in ovaries of both intact and eyestalk-ablated broodstock was greater than that of juveniles (P<0.05). Pgmrc1 was up-regulated in mature (stage IV) ovaries of intact broodstock (P<0.05). Unilateral eyestalk ablation resulted in an earlier up-regulation of Pgmrc1 since the vitellogenic (II) ovarian stage. Moreover, the expression level of Pgmrc1 in vitellogenic, early cortical rod and mature (II-IV) ovaries of eyestalk-ablated broodstock was greater than that of the same ovarian stages in intact broodstock (P<0.05). Pgmrc1 mRNA was clearly localized in the cytoplasm of follicular cells, previtellogenic and early vitellogenic oocytes. Immunohistochemistry revealed the positive signals of the Pgmrc1 protein in the follicular layers and cell membrane of follicular cells and various stages of oocytes. Taken the information together, Pgmrc1 gene products seem to play the important role on ovarian development and may be used as the bioindicator for monitoring progression of oocyte maturation of P. monodon.

Genetic population differentiation of the blue swimming crab Portunus pelagicus (Portunidae) in Thai waters revealed by RAPD analysis

Genetic diversity and population differentiation of the blue swimming crab, Portunus pelagicus, in Thailand were analyzed by RAPD analysis. One hundred and twelve RAPD fragments were generated from 109 individuals of P. pelagicus using OPA02, OPA14, OPB10, UBC122, and UBC158 primers. The percentage of polymorphic bands in each geographic sample and that of each primer across overall samples were 72.7-85.0 and 92.0-100%, respectively. Large numbers of polymorphic bands found in the RAPD analysis suggested high genetic diversity of Thai P. pelagicus. The mean genetic distance between samples across all primers was 0.0929-0.2471. Significant geographic heterogeneity was observed across samples overall and between all pairs of geographic samples (P < 0.01 for theta and P < 0.0001 for the exact test), indicating strong genetic differentiation of P. pelagicus in Thai waters, despite its high potential of dispersal. Limited gene flow levels (0.44-1.19 individuals per generation) of Thai P. pelagicus were also observed. A fine scale level of differentiation suggested that P. pelagicus from each geographic sample in Thai waters should be regarded as a separate genetic population and treated as a different exploited stock.

Identification of testis-relevant genes using in silico analysis from testis ESTs and cDNA microarray in the black tiger shrimp (Penaeus monodon)

Background

Poor reproductive maturation of the black tiger shrimp (Penaeus monodon) in captivity is one of the serious threats to sustainability of the shrimp farming industry. Understanding molecular mechanisms governing reproductive maturation processes requires the fundamental knowledge of integrated expression profiles in gonads of this economically important species. In P. monodon, a non-model species for which the genome sequence is not available, expressed sequence tag (EST) and cDNA microarray analyses can help reveal important transcripts relevant to reproduction and facilitate functional characterization of transcripts with important roles in male reproductive development and maturation.

Results

In this study, a conventional testis EST library was exploited to reveal novel transcripts. A total of 4,803 ESTs were unidirectionally sequenced and analyzed in silico using a customizable data analysis package, ESTplus. After sequence assembly, 2,702 unique sequences comprised of 424 contigs and 2,278 singletons were identified; of these, 1,133 sequences are homologous to genes with known functions. The sequences were further characterized according to gene ontology categories (41% biological process, 24% molecular function, 35% cellular component). Through comparison with EST libraries of other tissues of P. monodon, 1,579 transcripts found only in the testis cDNA library were identified. A total of 621 ESTs have not been identified in penaeid shrimp. Furthermore, cDNA microarray analysis revealed several ESTs homologous to testis-relevant genes were more preferentially expressed in testis than in ovary. Representatives of these transcripts, homologs of saposin (PmSap) and Dmc1 (PmDmc1), were further characterized by RACE-PCR. The more abundant expression levels in testis than ovary of PmSap and PmDmc1 were verified by quantitative real-time PCR in juveniles and wild broodstock of P. monodon.

Conclusions

Without a genome sequence, a combination of EST analysis and high-throughput cDNA microarray technology can be a useful integrated tool as an initial step towards the identification of transcripts with important biological functions. Identification and expression analysis of saposin and Dmc1 homologs demonstrate the power of these methods for characterizing functionally important genes in P. monodon.

Suppression subtractive hybridization (SSH) for isolation and characterization of genes related to testicular development in the giant tiger shrimp Penaeus monodon

Suppression subtractive hybridization (SSH) cDNA libraries of the giant tiger shrimp, Penaeus monodon, were constructed. In total, 178 and 187 clones from the forward and reverse SSH libraries, respectively, of P. monodon were unidirectionally sequenced. From these, 37.1% and 53.5% Expressed Sequence Tags (ESTs) significantly matched known genes (E-value < 1e-04). Three isoforms of P. monodon progestin membrane receptor component 1: PM-PGMRC1-s (1980 bp), PM-PGMRC1-m (2848 bp), and PM-PGMRC1-l (2971 bp), with an identical ORF of 573 bp corresponding to a deduced polypeptide of 190 amino acids, were successfully identified by RACE-PCR. Interestingly, PMPGMRC1 showed a greater expression level in testes of juvenile than broodstock P. monodon (P < 0.05). Dopamine administration (10(-6) mol/shrimp) resulted in up-regulation of PMPGMRC1 in testes of juveniles at 3 hrs post treatment (P < 0.05), but had no effect on PM-Dmc1 (P > 0.05).

Expressed sequence tag analysis for identification and characterization of sex-related genes in the giant tiger shrimp Penaeus monodon

Sex-related genes expressed in vitellogenic ovaries of the giant tiger shrimp, Penaeus monodon, were identified by an EST approach. A total of 1051 clones were unidirectionally sequenced from the 5 terminus. Nucleotide sequences of 743 EST (70.7%) significantly matched known genes previously deposited in the GenBank (E-value <10(-4)) whereas 308 ESTs (29.3%) were regarded as newly unidentified transcripts (E-value >10(-4)). A total of 559 transcripts (87 contigs and 472 singletons) were obtained. Thrombospondin (TSP) and peritrophin (79 and 87 clones accounting for 7.5 and 8.3% of clones sequenced, respectively) predominated among characterized transcripts. Several full length transcripts (e.g. cyclophilin, profillin and thioredoxin peroxidase) were also isolated. A gene homologue encoding chromobox protein (PMCBX, ORF of 567 nucleotides encoding a protein of 188 amino acids) which is recognized as a new member of the HP1 family was identified. Expression patterns of 14 of 25 sex-related gene homologues in ovaries and testes of P. monodon broodstock were examined by RT-PCR. Female sterile and ovarian lipoprotein receptor homologues were only expressed in ovaries whereas the remaining transcripts except disulfide isomerase related P5 precursor and adenine nucleotide translocator 2 were higher expressed in ovaries than testes of P. monodon broodstock. A homologue of ubiquitin specific proteinase 9, X chromosome (Usp9X) revealed a preferential expression level in ovaries than testes of broodstock-sized P. monodon (N = 13 and 11, P <0.05) but was only expressed in ovaries of 4-month-old shrimp (N = 5 for each sex).

Genetic heterogeneity of the blue swimming crab (Portunus pelagicus) in Thailand determined by AFLP analysis

Genetic diversity and population differentiation of the blue swimming crab (Portunus pelagicus) in Thailand, originating from Ranong and Krabi located in the Andaman Sea (west) and Chanthaburi, Prachuap Khiri Khan, and Suratthani located in the Gulf of Thailand (east), were examined by AFLP analysis. High genetic diversity of P. pelagicus in Thai waters was found (N=72). The four primer combinations generated 227 AFLP fragments, and the percentage of polymorphic bands in each geographic sample was 66.19-94.38%. The mean genetic distance between pairs of samples was 0.1151-0.2440. Geographic heterogeneity analyses using the exact test and FST-based statistics between all pairwise comparisons were statistically significant (P<0.01), indicating a fine-scale level of intraspecific population differentiation of Thai P. pelagicus. The estimated number of migrants per generation (Nem) was 0.26-0.76, suggesting restricted gene flow levels of P. pelagicus in Thai waters.

Genetic diversity of the giant tiger shrimp (Penaeus monodon) in Thailand revealed by PCR-SSCP of polymorphic EST-derived markers

A total of 90 ESTs from normal and 157 from subtractive ovarian cDNA libraries of the giant tiger shrimp (Penaeus monodon) were sequenced. SSCP analysis of disulfide isomerase (DSl), zinc finger protein (ZFP), PMO920, and PMT1700 was carried out for population genetic studies of P. monodon in Thai waters. The number of codominant alleles per locus for overall samples was 6 for PMO920, 5 for PMT1700, and 12 for ZFP, and there were 19 dominant alleles for DSI. The observed heterozygosity of each geographic sample was 0.3043-0.5128 for PMO920, 0.3462-0.4643 for PMT1700, and 0.5000-0.8108 for ZFP. Linkage disequilibrium analysis indicated that genotypes of these loci segregate randomly (P > 0.05). Low genetic distance was found between pairs of geographic samples (0.0077-0.0178). The neighbor-joining tree constructed from the average genetic distance of overall loci allocated the Andaman samples (Satun, Trang, and Phangnga) into one cluster, and Chumphon and Trat into other clusters. Geographic differentiation between Satun-Trat and Satun-Phangnga was found only at the ZFP locus (P < 0.05), suggesting low degrees of genetic subdivision of Thai P. monodon.

Identification of sex-specific expression markers in the giant tiger shrimp (Penaeus monodon)

Bulked segregant analysis (BSA) and AFLP were used for isolation of genomic sex determination markers in Penaeus monodon. A total of 256 primer combinations were tested against 6-10 bulked genomic DNA of P. monodon. Five and one candidate female- and male-specific AFLP fragments were identified. Female-specific fragments were cloned and further characterized. SCAR markers derived from FE10M9520, FE10M10725.1, FE10M10725.2 and FE14M16340 provided the positive amplification product in both male and female P. monodon. Further analysis of these markers using SSCP and genome walk analysis indicated that they were not sex-linked. In addition, sex-specific (or differential) expression markers in ovaries and testes of P. monodon were analyzed by RAP-PCR (150 primer combinations). Twenty-one and fourteen RAP-PCR fragments specifically/differentially expressed in ovaries and testes of P. monodon were successfully cloned and sequenced. Expression patterns of 25 transcripts were tested against the first stranded cDNA of ovaries and testes of 3-month-old and broodstock-sized P. monodon (N=5 and N=7-10 for females and N=4 and N=5-7 for males, respectively). Five (FI-4, FI-44, FIII-4, FIII-39 and FIII-58) and two (M457-A01 and MII-51) derived RAP-PCR markers revealed female- and male-specific expression patterns in P. monodon. Surprisingly, MII-5 originally found in testes showed a higher expression level in ovaries than did testes of juvenile shrimps but a temporal female-specific pattern in P. monodon adults.

Species identification of five penaeid shrimps using PCR-RFLP and SSCP analyses of 16S ribosomal DNA

DNA-based molecular markers for differentiation of five penaeid shrimps (Penaeus monodon, P. semisulcatus, Feneropenaeus merguiensis, Litopenaeus vannamei and Marsupenaeus japonicus) were developed based on polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and single-stranded conformation polymorphism (SSCP) of 16S ribosomal (r) DNA. Differentiation of P. monodon, P. semisulcatus and L. vannamei can be unambiguously carried out by PCRRFLP of 16S rDNA(560) whereas P. semisulcatus and M. japonicus shared a BABB mitotype. These shrimps were successfully discriminated by SSCP analysis of 16S rDNA(560). Nevertheless, the amplification success for L. vannamei and F. merguiensis was not consistent when tested against larger sample sizes. As a result, 16S rDNA(560) of an individual representing the most common mitotype of each species was cloned and sequenced. The new primer pair was designed and tested against the large sample sizes (312 bp product, N = 185). The amplification success was consistent across all species. PCR-RFLP of 16S rDNA(312) was as effective as that of 16S rDNA(560). Differentiation of all shrimp species were successfully carried out by SSCP analysis.

Molecular taxonomy of cupped oysters (Crassostrea, Saccostrea, and Striostrea) in Thailand based on COI, 16S, and 18S rDNA polymorphism

Genetic diversity of oysters Crassostrea belcheri (Sowerby, 1871), C. iredalei (Faustino, 1932), Saccostrea cucullata (Born, 1778), S. forskali (Gmelin, 1791), and Striostrea (Parastriostrea) mytiloides (Lamarck, 1819) (Ostreoida, Mollusca) was analyzed by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) of 16S ribosomal DNA with AcsI, AluI, DdeI, DraI, RsaI, and TaqI, 18S ribosomal DNA with HinfI, and cytochrome oxidase subunit I with AcsI, DdeI and MboI. A total of 54 composite haplotypes were observed. Species-diagnostic markers were specifically found in C. belcheri, C. iredalei, and S. cucullata, but not in S. forskali and Striostrea mytiloides, which shared common composite haplotypes. Neighbor-joining trees constructed from genetic distances between pairs of composite haplotypes and species indicated large genetic differences between Crassostrea and Saccostrea (including Striostrea mytiloides), but closer relationships were observed within each genus. Four groups of unidentified oysters (Crassostrea sp. and Saccostrea sp. groups 1, 2, and 3) were also genetically analyzed. Fixed RFLP markers were found in Crassostrea sp. and Saccostrea sp. group 2, but not in Saccostrea sp. groups 1 and 3. Phylogenetic and genetic heterogeneity analyses indicated that Crassostrea sp. and Saccostrea sp. group 2 should be considered as newly unidentified oyster species in Thailand.

Generation of monoclonal antibodies specific to Hepatopancreatic parvovirus (HPV) from Penaeus monodon

Hepatopancreatic parvovirus (HPV) was isolated from the hepatopancreas (HP) of slow growth Penaeus monodon by urografin gradient centrifugation. The presence of HPV in the fraction was monitored by PCR and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Only 1 major 54 kDa protein band was observed in the strong PCR-positive fractions used to immunize mice for monoclonal antibody production. After cell fusion, the first step in selecting specific antibodies was performed by dot-blot assay with purified HPV viral particles. The second screening step was carried out using Western blots of purified HPV proteins and immunohistochemistry of HPV-infected HP tissue. Four monoclonal antibodies were isolated; these bound to the 54 kDa protein in Western blots and to intranuclear inclusion bodies in tubule epithelial cells of HPV-infected prawn tissue by immunohistochemistry. None of the antibodies showed cross-reactivity either to uninfected shrimp tissue or to other shrimp viruses tested. These reagents have potential for use in developing a highly sensitive immunoassay such as sandwich ELISA or a convenient kit for detection of HPV infection.

Differences in susceptibility of palaemonid shrimp species to yellow head virus (YHV) infection

Five species of palaemonid shrimp, Macrobrachium rosenbergii, M. lanchesteri, M. sintangense, Palaemon styliferus and P. serrifer, were collected from Penaeus monodon farming areas in Thailand. Some of each species were artificially infected with yellow head virus (YHV) by injection and then monitored by RT-PCR and by immunohistochemistry using monoclonal antibodies specific to 116 kDa, 64 kDa, and 20 kDa proteins of YHV. Natural YHV infections were not detected in any of the shrimp examined. In YHV injection experiments, a high proportion of P. serrifer, P. styliferus and M. sintangense exhibited mild to moderate YHV infections at 3 d post-injection. The severity of infection was reduced in shrimp that survived to 10 and 30 d post-injection. Using immunohistochemistry and RT-PCR, a small proportion of M. lanchesteri showed very mild YHV infections at Day 3 but no infections at Days 10 and 30. No YHV infections resulted in M. rosenbergii. The evidence suggested that M. sintangense, P. styliferus and P. serrifer are susceptible to YHV and carry it for some time. In contrast, M, rosenbergii and M. lanchesteri appear to resist YHV infection and eliminate YHV efficiently. Because they display a range of responses to YHV, palaemonid shrimp may serve as a good model for studying YHV defense mechanisms in shrimp.

Genetic Heterogeneity of the Tropical Abalone (Haliotis asinina) Revealed by RAPD and Microsatellite Analyses

Genetic heterogeneity of the tropical abalone, Haliotis asinina was examined using randomly amplified polymorphic DNA (RAPD) and microsatellite analyses. One hundred and thirteen polymorphic RAPD fragments were generated. The percentage of polymorphic bands of H. asinina across overall primers was 85.20%. The average genetic distance of natural samples within the Gulf of Thailand (HACAME and HASAME) was 0.0219. Larger distance was observed when those samples were compared with HATRAW from the Andaman Sea (0.2309 and 0.2314). Geographic heterogeneity and F(ST) analyses revealed population differentiation between H. asinina from the Gulf of Thailand and the Andaman Sea (p < 0.0001). Three microsatellite loci (CUHas1, CUHas4 and CUHas5) indicated relatively high genetic diversity in H. asinina (total number of alleles = 26, 5, 23 and observed heterozygosity = 0.84, 0.42 and 0.33, respectively). Significant population differentiation was also found between samples from different coastal regions (p < 0.0001). Therefore, the gene pool of natural H. asinina in coastal Thai waters can be genetically divided to 2 different populations; the Gulf of Thailand (A) and the Andaman Sea (B).

Monoclonal antibodies specific to haemocytes of black tiger prawn Penaeus monodon

Monoclonal antibodies specific to haemocytes of Penaeus monodon were generated from a mouse immunized with a mixture of SDS-treated and formalin-fixed haemocytes. Hybridoma clones were selected by immunohistochemistry against fixed haemocytes, heart, lymphoid organ, and haemopoietic tissue, and Western blot against haemocyte extract and haemolymph. Sixteen monoclonal antibodies specific to haemocytes were obtained and could be divided into six groups according to their binding capacities to various haemocyte proteins in Western blot analyses, 102, 43, approximately 20, 61, 175 and approximately 230 kDa, and their differences in recognition of haemocyte sub-populations. The first group of antibodies strongly recognized a small subset of semi-granulocytes (SG) and hyalinocytes (H) but occasionally stained lightly a very small population of granulocytes (G). The antibodies also bound to a group of cells in haemopoietic tissue as well as cells located at the inner layers of the tubules in the lymphoid organ but not in the spheroid. The second group of antibodies strongly bound to a large sub-population of G and SG with coarse granules but did not bind to most of the H. This group of antibodies also cross-reacted with cells in the outer layer of the tubules in the lymphoid organ. The third group of antibodies recognized all G and only a small portion of SG. The fourth, fifth and sixth groups bound to sub-populations of G, SG and H in similar proportions. None of the antibodies showed any cross-reactivity to other components in haemolymph. The common antigens recognized by the first and the second groups of antibodies in the haemopoietic tissue and the lymphoid organ may reflect relationships among these organs in the development of the sub-populations of G and SG. Haemopoietic tissue may be the site for haemocyte production and the lymphoid organ may be the site for further differentiation of at least two different lines of haemocytes.

Population structure of tropical abalone (Haliotis asinina) in coastal waters of Thailand determined using microsatellite markers

Three partial genomic libraries were constructed from genomic DNA of the tropical abalone (Haliotis asinina) that was digested with AluI, vortexed/sonicated, and digested with mixed enzyme (AluI, HincII, and RsaI). The libraries yielded 0.02%, 0.42%, and 1.46% positive microsatellite-containing clones, respectively. Eleven clones each of perfect, imperfect, and compound microsatellites were isolated. Ten primer pairs (CUHas1-CUHas10) were analyzed to evaluate their polymorphic level. The numbers of alleles per locus, observed heterozygosity (H0), and expected heterozygosity (He) ranged from 3 to 26 alleles, and varied between 0.27 and 0.85 and between 0.24 and 0.93, respectively. Three microsatellite loci (CUHas2, CUHas3, and CUHas8) were further used for examination of genetic diversity and differentiation of natural H. asinina in coastal waters of Thailand. Genetic variabilities in terms of the effective number of alleles (n(e)), H0, and He were higher in 2 samples from the Gulf of Thailand (n(e)=9.37, 7.66; H0=0.62, 0.78; and He=0.87, 0.86) than those of one sample (n(e)=6.04; H0=0.58; and He=0.62) derived from the Andaman Sea. Assessment of genetic heterogeneity, including allele frequency comparison and pairwise F(ST) analysis, indicated interpopulational differentiation, between natural H. asinina from the Gulf of Thailand and that from the Andaman Sea (P<0.0001).

Species identification of the tropical abalone (Haliotis asinina, Haliotis ovina, and Haliotis varia) in Thailand using RAPD and SCAR markers

A randomly amplified polymorphic DNA (RAPD) analysis was used to identify the species- and population-specific markers of abalone; Haliotis asinina, H. ovina, and H. varia in Thai waters. Fifteen species-specific and six population-specific RAPD markers were identified. In addition, an 1650 bp band (UBC195) that was restricted to H. ovina from the Gulf of Thailand (east) was also found. All of the specific RAPD markers were cloned and sequenced. Twenty pairs of primers were designed and specificity-tested (N = 12 and 4 for target and non-target species, respectively). Seven primer pairs (CUHA1, 2, 4, 11, 12, 13, and 14) were specifically amplified by H. asinina DNA, whereas a single pair of primers showed specificity with H. ovina (CUHO3) and H. varia (CUHV1), respectively. Four primer pairs, including CUHA2, CUHA12, CUHO3, and CUHV1, were further examined against 216 individuals of abalone (N = 111, 73, and 32, respectively). Results indicated the species-specific nature of all of them, except CUHO3, with the sensitivity of detection of 100 pg and 20 pg of the target DNA template for CUHA2 and CUHA12 and CUHV1, respectively. The species-origin of the frozen, ethanol-preserved, dried, and boiled H. asinina specimens could also be successfully identified by CUHA2.

Genetic Diversity and Molecular Markers in Introduced and Thai Native Apple Snails (Pomacea and Pila)

The genetic diversity and species-diagnostic markers in the introduced apple snail, Pomacea canaliculata and in the native Thai apple snails; Pila ampullacea, P. angelica, P. pesmei, and P. polita, were investigated by restriction analysis of COI and are reported for the first time. Twenty-one composite haplotypes showing non-overlapping distributions among species were found. Genetic heterogeneity analysis indicated significant differences between species (P < 0.0001) and within P. pesmei (P < 0.0001) and P. angelica (P < 0.0004). No such heterogeneity was observed in Pomacea canaliculata (P > 0.0036 as modified by the Bonferroni procedure), P. ampullacea (P = 0.0824-1.000) and P. polita (P = 1.0000). A neighbor-joining tree based on genetic distance between pairs of composite haplotypes differentiated all species and indicated that P. angelica and P. pesmei are closely related phylogenetically. In addition, the 16S rDNA of these species was cloned and sequenced. A species-specific PCR for P. canaliculata was successfully developed with a sensitivity of detection of approximately 50 pg of the target DNA template. The amplification of genomic DNA (50 pg and 25 ng) isolated from the fertilized eggs, and juveniles (1, 7, and 15 d after hatching) of Pomacea canaliculata was also successful, and suggested that Pomacea canaliculata and Pila species can be discriminated from the early stages of development.

Genetic diversity and molecular markers of the tropical abalone (Haliotis asinina) in Thailand

Genetic diversity of abalone in Thailand, Haliotis asinina, H. ovina, and H. varia, was analyzed by polymerase chain reaction (PCR) of 18S and 16S rDNAs, with randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP). Species-specific RAPD markers were found in each abalone species. Restriction analysis of 18S (nuclear) ribosomal DNA with Alu I, Taq I, and Hae III and 16S (mitochondrial) rDNA with Bam HI, Eco RI, Hae III, and Alu I gave 12 and 13 digestion patterns, respectively. A total of 49 composite haplotypes were found. A dendogram obtained by the unweighted pair-group method with arithmetic mean, constructed from divergence between pairs of composite haplotypes, revealed reproductively isolated gene pools of these abalone and indicated that H. asinina and H. ovina are genetically closer than H. varia. When H. varia was discovered owing to small sample sizes, geographic heterogeneity analysis and FST estimate indicated clear genetic differentiation between H. ovina originating from the Andaman Sea (west) and the Gulf of Thailand (east, P<0.0001), whereas partial differentiation was observed between the Philippines and the remaining H. asinina samples (P<0.0021). The amplified 16S rDNAs of individuals representing composite haplotypes found in this study were cloned and sequenced. A neighbor-joining tree constructed from sequence divergence of 16S rDNA accurately allocated those sequences according to species origins of abalone. Species-specific PCR based on 16S rDNA polymorphism was successfully developed in H. asinina and H. varia but not in H. ovina.

Enhanced growth and resistance to Vibrio challenge in pond-reared black tiger shrimp Penaeus monodon fed a Bacillus probiotic

The bacterial probiont Bacillus S11 (BS11) was used as a supplement in feed (PF) for black tiger shrimp Penaeus monodon in 2 earthen pond field-trials carried out for 100 d during 2 different seasons in Thailand. Growth and survival were compared with those of shrimp receiving an unsupplemented feed (UF). In the hot and cool seasons, respectively, shrimp fed PF grew significantly larger and had significantly higher survival than shrimp fed UF (p < 0.05). Projected yields on an annual basis (two 100 d crops) were 49% greater with PF-fed shrimp. In 8 d challenge tests using the luminescent bacterium Vibrio harveyi 1526, shrimp fed UF all died within 6 d while survival for shrimp fed PF was 5 and 9%.

Mycaperoxide H, a new cytotoxic norsesterterpene peroxide from a Thai marine sponge Mycale sp

Mycaperoxide H, a new cyclic norsesterterpene peroxide, was isolated from a Thai marine sponge Mycalesp. The structure of mycaperoxide H was deduced by spectroscopic and chemical analysis. Mycaperoxide H was cytotoxic against HeLa cells with an IC(50) value of 0.8 microgram/mL.

Water pollution and habitat degradation in the Gulf of Thailand

The Gulf of Thailand has been a major marine resource for Thai people for a long time. However, recent industrialization and community development have exerted considerable stress on the marine environments and provoked habitat degradation. The following pollution problems in the Gulf have been prioritized and are discussed in details: (1) Untreated municipal and industrial waste water are considered to be the most serious problems of the country due to limited waste water treatment facilities in the area. (2) Eutrophication is an emerging problem in the gulf of Thailand. Fortunately, the major species of phytoplankton that have been reported as the cause of red tide phenomena were non-toxic species such as Noctiluca sp. and Trichodesmium sp. (3) Few problems have been documented from trace metals contamination in the Gulf of Thailand and public health threat from seafood contamination does not appear to be significant yet. (4) Petroleum hydrocarbon residue contamination is not a problem, although a few spills from small oil tankers have been recorded. A rapid decrease in mangrove forest, coral reefs, and fisheries resources due to mismanagement is also discussed.

Monoclonal antibodies specific to yellow-head virus (YHV) of Penaeus monodon

Monoclonal antibodies specific to 22, 67 and 135 kDa proteins of yellow-head virus (YHV) were produced from a mouse immunized with partially purified YHV isolated from the haemolymph of experimentally YHV-infected Penaeus monodon. Four groups of monoclonal antibodies were identified. One group of antibodies bound only to native protein of YHV while the others were specific to 135, 67 and 22 kDa proteins in both native and denatured forms. All antibodies could be used to detect YHV infection by means of dot blot and immunohistochemistry. However, antibodies specific to the 22 kDa protein gave the best immunohistochemistry results in terms of intensity and sharpness of staining.

Genetic heterogeneity of the giant tiger shrimp (Penaeus monodon) in Thailand revealed by RAPD and mitochondrial DNA RFLP analyses

Genetic diversity of the giant tiger shrimp (Penaeus monodon) collected from 5 areas, Chumphon and Trat (Gulf of Thailand), and Phangnga, Satun, and Trang (Andaman Sea), was examined by randomly amplified polymorphic DNA (RAPD) and mitochondrial DNA (16S ribosomal DNA and an intergenic COI-COII) polymorphism. A total of 53 polymorphic fragments from UBC299, UBC273, and UBC268 was consistently scored across all samples. From the respective primers 26, 32, and 30 genotypes were generated. A 260-bp RAPD fragment generated by the primer UBC268 was specifically observed in 95.8% of Trat P. monodon, suggesting that this RAPD could be used as a marker for comparing phenotypic performance of P. monodon from Trat and other geographic samples. In addition, 37 mtDNA composite haplotypes were observed from restriction analysis of the same P. monodon samples. High haplotype diversity (0.855) and nucleotide diversity (3.328%) of Thai P. monodon were observed. Population differentiation of P. monodon between the Andaman Sea and Gulf of Thailand was clearly illustrated by both techniques (P <.0001). Nevertheless, contradictory results on patterns of differentiation were observed between P. monodon within the Gulf of Thailand. Analysis of nuclear DNA polymorphism (RAPD) indicated a genetically significant difference between Chumphon and Trat ( P <.0001), whereas mtDNA polymorphism did not show differentiation between these samples (P =.0497). Under the presumption of selective neutrality of these markers, biased female gene flow between Trat and Chumphon P. monodon may exist and be responsible for an anomalous differentiation pattern between these geographic samples.

Development of a monoclonal antibody specific to yellow head virus (YHV) from Penaeus monodon

A monoclonal antibody specific to yellow head virus (YHV) was produced from a mouse immunized with gill extracts prepared from laboratory-reared Penaeus monodon dually infected with YHV and white spot syndrome virus (WSSV). One clone designated V3-2B specifically bound to native and SDS-treated viral specific antigens. Immunocytochemical studies of infected gills revealed viral specific immunoreactivities in the cytoplasm of gill tissue and in haemocytes. No antibody binding was observed in gills from non-infected shrimp. In addition, immunocytochemical examination of tissues from shrimp experimentally infected with YHV gave a positive reaction, while tissues from uninfected control shrimp or shrimp experimentally infected with WSSV did not. Western blot analysis indicated that the antibody reacted with a protein of approximately 135 kD that was present only in shrimp infected with YHV. In dot-blot indirect immunoperoxidase assays, the antibody was able to detect viral associated antigen in diluted haemolymph up to 1:50 dilution and in an ammonium sulfate precipitate of haemolymph up to 1:1000 dilution. The results suggested that this antibody might be useful for development of effective diagnostic techniques for both heavy and mild YHV infections in shrimp.

New macrolactins from a marine Bacillus sp. Sc026

Bioassay-guided fractionation of the EtOAc extract of a marine Bacillus sp. Sc026 culture broth has led to the isolation of the known compound, macrolactin F (1), together with two new compounds, 7-O-succinyl macrolactin F (2) and 7-O-succinyl macrolactin A (3). The chemical structures of 1-3 were elucidated on the basis of spectral data analyses and literature data comparison. Compounds 1-3 exhibited antibacterial activity against Bacillus subtilis and Staphylococcus aureus.