Black Tiger Prawn Penaeus Monodon Research Articles

Examination of the effects of triacylglycerol lipase on astaxanthin conversion in the black tiger prawn Penaeus monodon

The enzyme triacylglycerol lipase (TGL) catalyses the hydrolysis of triacylglycerols, and is characterized by catalytic esterification and ester exchange functionality. However, at present, there is comparatively little information regarding the sequences and functional validation of TGLs in crustaceans. In this study, we cloned the TGL1 gene of the black tiger prawn Penaeus monodon. The full-length cDNA of PmTGL1 comprises 1807 base pairs (bp), including an 80-bp 5′-untranslated region (UTR), a 149-bp 3′-UTR, and a 1578-bp open-reading frame (ORF), and encodes a putative 525-amino acid protein of 58.71 kDa with a theoretical isoelectric point of 4.81. Homology and phylogenetic tree analyses revealed that PmTGL1 is most closely related to the TGL of Penaeus chinensis, with which it clusters in a single group (similarity of up to 97.52%). Quantitative real-time PCR analysis further revealed that PmTGL1 is most highly expressed in the shrimp hepatopancreas. Although the expression of PmTGL1 was not significantly influenced by the differences in the background colour of the rearing pond, it was significantly promoted in response to dietary supplementation with astaxanthin. As an adipokinetic hormone in P. monodon, PmRPCH (red pigment-concentrating hormone) plays an important role in body colour changes and lipid metabolism. Based on our findings, we speculate that the PmTGL1 facilitates astaxanthin metabolism in P. monodon via the hydrolysis of esterified astaxanthin to yield free astaxanthin and that the activity of TGL in these shrimps is regulated via an adipokinetic hormone cascade.

IDENTIFICATION OF TROPOMYOSIN AS THE MAJOR ALLERGEN OF BLACK TIGER PRAWN (PENAEUS MONODON) BY AN ALLERGENOMIC APPROACH

Shellfish has been recognized as one of the leading causes of food allergy in both adults and children in Asia Pacific region. In Malaysia, black tiger prawn (Penaeus monodon) is among the most widely consumed species. Our previous studies have successfully identified several major allergens including a thermostable protein of 36 kDa. Thus the aim of this study was to identify the 36 kDa major allergen by an allergenomic approach. Protein extracts of raw prown were prepared and resolved by 2-dimensional electrophoresis (2-DE). Immunoblotting was then performed using sera from patients with prawn allergy. Selected spot from 2-DE was then excised, digested and analyzed by mass spectrometry. The 2-DE profile of the extract revealed approximately 100 protein spots between pH of ~4 to 10 and the size range between (<10 to 250 kDa). The 2-DE immunoblotting has detected numerous IgE-binding spots at 36 kDa. Mass spectrometry analysis of the major IgE-binding spot (spot 1a) has identified the 36 kDa spot as tropomyosin. Our findings indicated that tropomyosin play a major role in allergic reaction to black tiger prawn among local patients with prawn allergy, and should be included in diagnostics and therapeutic strategies of this allergy.

Nutrient efficacy of microalgae as aquafeed additives for the adult black tiger prawn,Penaeus monodon

This study used a small amount of several lyophilized microalgae (5% of dry weight in aquafeed) to feed adult black tiger prawns Penaeus monodon for 4 weeks, aiming to promote prawn health and nutritional level. Apart from slight increases in ash content, chlorophyll and β-carotene in the microalgae-added feeds, there was no difference from the commercial diet in their biochemical composition. After 28 days of feeding, prawn body length, body weight, condition index and also total amount of fatty acids and amino acids of the flesh (2nd abdominal segment) were not affected by microalgae additives as compared with the control commercial diet-fed group (P > 0.05). Prawns fed the microalgae diets, however, had a relatively better survival rate than those fed the commercial control diet, although no statistical significance was detected in any except for the diatom Melosira sp. The elevated survival rate was concomitant with a higher phagocytosis rate and superoxide dismutase (SOD) activity in the immune response analysis, and significantly a higher astaxanthin content detected in the tail muscle of microalgae diet-fed prawns (5.36–10.78 ng of astaxanthin per gram of muscle DW). These findings demonstrated that low-inclusion microalgal additives in prawn diets over a short feeding period (4 weeks) can result in healthier adult prawn, and hence could contribute to the development of an optimized feeding strategy for prawn aquaculture close to harvesting.

Differential expression microarrays reveal candidate genes potentially associated with reproductive dysfunction of captive-reared prawn Penaeus monodon

The Black tiger prawn Penaeus monodon is an internationally significant aquaculture species. However, partial dependence on wild-caught broodstock, due to compromised fecundity in most captive-reared animals, remains a major constraint to industry development. Reproductive performance of captive-reared females is often characterised by longer latency period, lower egg production, egg hatch rates and post-larval survivorship compared with their wild-caught counterparts. Improved understanding of the cellular and associated molecular events occurring during penaeid ovarian maturation could therefore be fundamental to improving reproductive success of captive-reared animals. In support of other studies (Brady et al., 2012) that focussed on non-ovarian tissues, this present study considered both gene expression and histological analyses of ovarian tissue (i.e. developing oocytes) and revealed differences between wild-caught and captive-reared P. monodon, including reduced lipid accumulation in oocytes of captive-reared animals. We have employed oligonucleotide microarray analysis to compare expression profiles of genes involved in ovarian maturation among wild-caught and captive-reared animals. Custom oligonucleotide microarrays were constructed and screened with transcripts derived from the ovary, cephalothorax and eyestalk from animals of all ovarian maturation stages. Ovarian maturation-related differential expression patterns were observed for 111 transcripts, with 53 transcripts displaying differential expression between wild-caught and captive-reared animals. Notably transcripts encoding vitellogenin — the major egg yolk protein precursor, and a lipid storage droplet protein (which we named pmLSD) which is involved in lipid accumulation, were found to have higher expression in wild-caught animals. pmLSD transcripts localise to pre-vitellogenic oocytes of wild-caught animals and the pmLSD protein is exclusively localised to the surface of lipid droplets of oocytes at vitellogenic and cortical rod stages. Our identification of differentially expressed genes, and in particular those encoding a PAT-family lipid storage droplet protein, pmLSD, may provide the molecular tools for further functional characterisation in prawns and improvement of reproductive success among captive-reared animals.

Molecular analysis of the QM gene from Penaeus monodon and its expression on the different ovarian stages of development

In present study, a QM gene was obtained from the ovary and neurosecretory organ in eyestalk cDNA library of black tiger prawn (Penaeus monodon). The full-length black tiger prawn QM (PmQM) cDNA contained a 5'-UTR of 41 bp, an ORF of 663 bp encoding a polypeptide of 220 amino acids with molecular weight 25.5 kDa, and a 3'-UTR of 54 bp. Homology analysis of the deduced amino acid sequence of the PmQM with other known QM sequences by MatGAT software revealed that the PmQM was high homology with other invertebrates. A conserved signature sequence of the QM family was found in the PmQM deduced amino acid sequence. Analysis of the tissue expression pattern of the PmQM gene showed that the PmQM mRNA was expressed in all tissues tested, with highest levels in ovary. Furthermore, the PmQM expression was found to be different in three important ovarian stages of development. The results indicated PmQM might play an important role in ovarian development.

Decreasing of heterogeneity in black tiger prawn (Penaeus monodon) and white shrimp (Litopenaeus vannamei) broodstocks and their fry produced in hatchery

<p>Domestication and genetic improvement of shrimp are required towards production of superior broodstock. BBPBAP Jepara had performed study on evaluation of genetic diversity of black tiger and white shrimp broodstock and their progenies produced in hatchery, using <em>Restriction Fragment Length Polymorphism</em> (RFLP)-mtDNA method. Amplification of black tiger shrimp mtDNA used primers designed based on 16S rDNA sequences, and the products were restricted by <em>Nde</em> II enzyme. While the primers for white shrimp was based on COIL and COIH sequences, and their PCR products were digested with <em>Nla</em> III. The results of study showed that heterogeneity of tiger shrimp derived from Aceh waters was 0.1063, while their F1 progeny was 0.0494. Heterogeneity of male tiger shrimp from Aceh waters and their progeny was 0.2811 and 0.1023, respectively, while of female was 0.1594 and 0.0940, respectively. Heterogeneity of F1 tiger shrimp from Sunda Strait was 0.0405, while their F2 was homozygous. Heterogeneity of F1 male and female tiger shrimp from Sunda Strait was 0.0641 and 0.1567, respectively, while of F2 was homozygous for both male and female. Heterogeneity value of F1 white shrimp from Hawaii was 0.0069, while the F2 was homozygous. Heterogeneity of F1 male and female white shrimp was 0.0099 and 0.0234, respectively, while of their F2 for both male and female were homozygous. Homozygous has been found in F1 of white shrimp broodstock from Florida. Based on the results of study, genetic variation of tiger shrimp and white shrimp broodstock used in hatchery were decrease. Combination of conventional selective breeding approach and molecular technique may be useful to faster to meet the goal of domestication and quality improvement of penaeid species in Indonesia.</p> <p>Keywords: black tiger shrimp, white shrimp, RFLP, heterogeneity, genetic marker.</p> <p> </p> <p>ABSTRAK</p> <p>Dalam rangka penyiapan induk-induk udang yang berkualitas unggul, diperlukan usaha untuk domestikasi dan perbaikan mutu genetik udang. Di BBPBAP Jepara telah dilakukan suatu kajian untuk mengevaluasi keragaman genetik induk udang windu dan udang vaname beserta keturunannya yang dihasilkan dari panti pembenihan dengan metode <em>Restriction Fragment Length Polymorphism</em> (RFLP)-mtDNA. Amplifikasi mtDNA udang windu menggunakan primer yang didisain berdasarkan sekuens 16S rDNA, dan produk PCR dipotong menggunakan enzim <em>Nde</em> II. Sementara primer untuk udang vaname dibuat berdasarkan sekuens COIL dan COIH, dan produk PCR dipotong dengan enzim <em>Nla</em> III.<a name="OLE_LINK2"></a><a name="OLE_LINK1"> Hasil penelitian menunjukkan bahwa nilai heterogenitas populasi induk udang windu asal Aceh dari alam sebesar 0,1063 dan turunan F1-nya sebesar 0,0494. Populasi induk windu jantan Aceh dari alam sebesar 0,2811 dan turunan F1-nya sebesar 0,1023; sedangkan populasi induk windu betina Aceh dari alam sebesar 0,1594 dan turunan F1-nya sebesar 0,0940. Nilai heterogenitas populasi induk udang windu asal Selat Sunda turunan F1 sebesar 0,0405 dan turunan F2-nya adalah homozigot. Populasi induk windu jantan Selat Sunda turunan F1 sebesar 0,0641 dan turunan F2-nya adalah homozigot; sedangkan populasi induk windu betina Selat Sunda turunan F1 sebesar 0,1567 dan turunan F2-nya adalah homozigot. Nilai heterogenitas populasi induk udang vaname asal Hawaii turunan F1 sebesar 0,0069 dan turunan F2 adalah homozigot. Populasi induk vaname jantan Hawaii turunan F1 sebesar 0,0099 dan turunan F2-nya adalah homozigot. Populasi induk betina Hawaii turunan F1 sebesar 0,0234 dan turunan F2-nya adalah homozigot. </a>Homozigositas pada induk udang vaname asal Florida telah terlihat pada turunan F1-nya. Hasil kajian ini menunjukkan adanya penurunan variasi genetik pada induk udang windu dan udang vaname yang digunakan di panti pembenihan. Kombinasi antara pendekatan selektif breeding konvensional dan aplikasi teknik molekuler mungkin bermanfaat untuk mempercepat tercapainya tujuan domestikasi dan perbaikan kualitas udang penaeid di Indonesia. </p> <p>Kata kunci : Udang windu, udang vaname, RFLP, heterogenitas, marker genetik</p>

Commentary on “Heritability and genetic correlations of growth and survival in black tiger prawn Penaeus monodon reared in tanks” [Aquaculture 259 (2006) 138–145

Commentary on “Heritability and genetic correlations of growth and survival in black tiger prawn Penaeus monodon reared in tanks” [Aquaculture 259 (2006) 138–145

Heritability of reproductive traits and genetic correlations with growth in the black tiger prawn Penaeus monodon reared in tanks

Captive-reared broodstock of the black tiger prawn ( Penaeus monodon) have exhibited poor reproductive performance limiting attempts to domesticate this species. The potential for improved reproductive performance was assessed by determining heritabilities of four measures of reproductive performance, their genetic correlations with each other and with growth rate and weight at age. Heritability estimates ( h 2 ± S.E.) obtained from √ (days to spawn), √ (egg number), √ (nauplii number) and arcsin√ (proportion hatched) were 0.47 ± 0.15, 0.41 ± 0.18, 0.27 ± 0.16, and 0.18 ± 0.16, respectively. Estimates of genetic correlations between reproductive traits and weight at age, or growth rate were less than 0.5 except for √ (egg number) and weight at 54 weeks (0.93 ± 0.19) and √ (egg number) and 16–54-week growth (0.63 ± 0.29).

Comparative analysis of barnacle tropomyosin: Divergence from decapod tropomyosins and role as a potential allergen

Tropomyosin, a myofibrillar protein of 35–38 kDa, represents a major and cross-reactive allergen in decapod crustaceans. This study was initiated to clarify whether decapod-allergic patients also recognize tropomyosins of barnacles, crustaceans phylogenetically remote from decapods, which are locally consumed as a delicacy. On SDS-PAGE, a 37 kDa protein was observed in all the heated extracts prepared from two species of decapods (American lobster Homarus americanus and black tiger prawn Penaeus monodon) and two species of barnacles (acorn barnacle Balanus rostratus and goose barnacle Capitulum mitella). In immunoblotting, the 37 kDa protein was found to react with monoclonal antibodies against American lobster tropomyosin and hence identified as tropomyosin. The patient sera reacted to tropomyosins from both decapods and barnacles and the reactivity was abolished by preincubation with American lobster tropomyosin, demonstrating that barnacle tropomyosins are allergens cross-reactive with decapod tropomyosins. However, the amino acid sequence of acorn barnacle tropomyosin, deduced by cDNA cloning experiments, shares higher sequence identity with abalone tropomyosins than with decapod tropomyosins. In accordance with this, the phylogenetic tree made for tropomyosins from various animals showed that the acorn barnacle tropomyosin is evolutionally classified not into the decapod tropomyosin family but into the molluscan tropomyosin family.

Productivity and Chemical Parameters in the Bottom Soil of 1 and 3 years operated pond of Black Tiger Prawn Penaeus monodon Fab. Culture

<p>This study was carried out to observe the productivity and bottom soil chemical aspects of 1 year and 3 years operated pond of black tiger prawn <em>Penaeus monodon</em> Fab. culture. The results of study depicted that pond operated for 3 years contained higher (P<0.05) organic carbon (10.36%) and nitrogen (0.22%), but lower Fe compared with 1-year-pond operated. Sulfur content tends to increase with increase in age of pond. Productivity of 3-year-pond was lower (P<0.05) than that of 1-year-pond operated.</p> <p>Keywords: black tiger shrimp, <em>Penaeus monodon</em>, soil chemistry, tambak bottom</p> <p> </p> <p>ABSTRAK</p> <p>Tujuan dari penelitian ini adalah untuk mengetahui produktivitas dan parameter-parameter kimia tanah dasar tambak budidaya udang (<em>Penaeus monodon </em>Fab.) yang telah beroperasi selama 1 dan 3 tahun. Hasil penelitian menunjukkan bahwa tambak umur 3 tahun mengandung karbon organik (10,36%) dan nitrogen (0,22%) lebih tinggi, sedangkan konsentrasi Fe cenderung lebih kecil dibandingkan tambak umur 1 tahun. Konsentrasi sulfur cenderung meningkat dengan bertambahnya umur tambak (P<0,05). Produktivitas tambak umur 3 tahun lebih rendah (P<0,05) dibandingkan tambak umur 1 tahun. </p> <p>Kata kunci: udang windu, <em>Penaeus monodon</em>, kimia tanah, dasar tambak</p>

Heritability and genetic correlations of growth and survival in black tiger prawn Penaeus monodon reared in tanks

Penaeus monodon were reared in captivity in tanks over three generations with full pedigree information. Weights of animals were measured at six ages between 7 and 54 weeks along with survival in each period. Females were more variable in weight than males after week 16, and variances between each sex were standardised prior to estimation of heritability and genetic correlations. The phenotypic mean (standard deviation) of weights at week 40 were 35 (6) g for males and 44 (10) g for females. Heritability with standard errors at 16, 30, 40 and 54 weeks were 0.56 ± 0.04, 0.55 ± 0.07, 0.45 ± 0.11 and 0.53 ± 0.14 respectively. Heritability for family survival, determined from mean survival within each family, was 0.51 + 0.18, 0.36 ± 0.18 and 0.71 ± 0.17 over periods 4 to 10, 10 to 16 and 16 to 32 weeks respectively. The genetic correlations between weight and survival revealed no significant trend. The results from this study indicate significant concurrent improvements in both growth and survival are possible through selective breeding.

Infectious hypodermal and hematopoietic necrosis virus (IHHNV)-related sequences in the genome of the black tiger prawn Penaeus monodon from Africa and Australia

We found an infectious hypodermal and hematopoietic necrosis virus (IHHNV)-related sequence within the shrimp genome in populations of Penaeus monodon from Africa and Australia. IHHNV is a singlestranded DNA virus that has caused severe mortality and stunted growth in penaeid shrimp. Recently, IHHNV-related sequences were found in samples of P. monodon from Madagascar and Tanzania. These sequences vary considerably (14 and 8%, respectively) from that of IHHNV found in association with viral epidemics. Laboratory bioassays were carried out with P. monodon and Litopenaeus vannamei to determine if either of these IHHNV-related sequences is infectious. We used juvenile and adult P. monodon containing the virus-related sequences from four geographic regions to generate inocula and tissues for feeding. Specific pathogen free P. monodon and L. vannamei were used as indicator shrimp. During the 2–4 week bioassays, none of the indicator shrimp showed signs of infection or disease. Results of both PCR assays and histological examination of the indicator shrimp were negative for IHHNV infection, indicating that the Africa type IHHNV-related sequences are not infectious. With the shrimp containing the Madagascar type IHHNV-related sequence (designated as type A), we performed genome walking at the 3′ end of the virus-related sequence and found that this virus-related sequence is part of the P. monodon genome. A fragment of 1.9 kb flanking sequence was cloned and sequenced. Sequence analysis showed that this flanking sequence contains shrimp microsatellite DNA. Also, its translated amino acid sequence was highly similar to a retrotransposon. This result provides molecular evidence that the type A IHHNV-related sequence is shrimp DNA. This sequence was found in the P. monodon collected from Africa and Australia.

Physiological Function and Metabolism of Free D-Alanine in Aquatic Animals

Aquatic crustaceans and some bivalve mollusks contain a large amount of free D-alanine (up to 100 mumol/g wet wt.) in their tissues. Under high salinity stress, crustaceans and bivalve mollusks largely accumulate D- and L-alanine irrespective of species examined, together with L-glutamine, L-proline, and glycine of which increases are species dependent. These data indicate that D-alanine is one of the major compatible osmolytes responsible for the intracellular isosmotic regulation in the tissues of crustaceans and bivalves. Alanine racemase has been proven to catalyze the interconversion of D- and L-alanine in these invertebrates. The enzyme has been isolated to homogeneity from the muscle of black tiger prawn Penaeus monodon and its cDNA has been cloned from the muscle and hepatopancreas of kuruma prawn Penaeus japonicus for the first time in eukaryotes other than yeast. Several fish species fed on crustaceans and mollusks contain D-amino acid and D-aspartate oxidases that catalyze the decomposition of D-amino acids. A cDNA of D-amino acid oxidase has been cloned from the hepatopancreas of omnivorous common carp Cyprinus carpio. During oral administration of free D-alanine to carp, the activity and mRNA of D-amino acid oxidase increased rapidly in hepatopancreas and the increases were highest in intestine followed by hepatopancreas and kidney. These data suggest that D-amino acid oxidase is inducible in carp and an important enzyme responsible for the efficient utilization of carbon skeleton of D-alanine in their feeds.

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, ∼20, 61, 175 and ∼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.

The effect of eyestalk homogenate on haemolymph vitellogenin levels in the black tiger prawn Penaeus monodon

Summary Competitive ELISA using a combination of monoclonal antibodies specific to vitellin subunits was used to monitor the fluctuation of haemolymph vitellogenin levels in Penaeus monodon during ovarian development induced by bilateral eyestalk-ablation and to monitor the effect of eyestalk homogenate injection in prawns with developing ovaries. The haemolymph vitellogenin levels were undetectable in the prawn with ovary at the resting stage but elevated sharply when the ovary began to develop, remained high during the ovary developing into the ripe stage, then fell to low levels before spawning and spent stages. The result from injection of eyestalk homogenate into prawns with developing ovaries revealed that haemolymph vitellogenin levels elevated sharply within 2 h, reached the maximal levels and remained high during 4–10 h, then declined slightly at 24 h. This response directly depended on the amount of injected eyestalk homogenate and the response was species specific. The application of eyestalk homogenate from Metapenaeus affinis demonstrated the same stimulatory effect but was less potent, whereas the eyestalk homogenate from Macrobrachium rosenbergii did not cause any changes in haemolymph vitellogenin levels. Therefore, the assay is specific and provides an indicator to monitor the activity of the putative gonad inhibiting hormone by assaying the alteration of vitellogenin levels.

Haliphthoros milfordensis isolated from black tiger prawn larvae (Penaeus monodon) in Vietnam

A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis.

Concentration and Composition of Astaxanthin in Black Tiger Prawn Penaeus monodon Postlarvae Fed Artemia sp. Nauplii or Mauxia Shrimsp Acetes intermedius

AbstractMinced Taiwan mauxia shrimp Acetes intermedius, an alternative to brine shrimp Artemia sp. nauplii, has long been used as a principal or supplemental feed in prawn hatcheries in Southeast Asia and India. In this study, black tiger prawn Penaeus monodon postlarvae were fed with frozen brine shrimp nauplii (diet B) or minced Taiwan mauxia shrimp (diet M) for 4 wk to compare their astaxanthin concentration and composition, survival, and growth. Diet B contained two and a half times more total carotenoid (TC) than diet M, with canthaxanthin as a major (79%) carotenoid, but without astaxanthin, a predominant carotenoid in crustaceans. Of its TC in diet M, 55% was β‐carotene and 17% astaxanthin. B‐prawn (postlarvae fed with diet B) had a similar growth rate as M‐prawn and twice the survival rate as M‐prawn. The concentrations of total astaxanthin (TA), free astaxanthin (FA), astaxanthin monoester (MA), and astaxanthin di‐ester (DA) in B‐prawn were all higher than those in M‐prawn. Except for FA, no reduction of TA, MA, or DA concentration during the feeding interval was found in B‐prawn. However, concentrations of TA, FA, MA, and DA in M‐prawn all decreased. TC content of the experimental diets had a greater influence on resulting prawn astaxanthin concentration and composition than carotenoid compositions of the diets.

Purification, properties, and partial amino acid sequences of alanine racemase from the muscle of the black tiger prawn Penaeusmonodon

Alanine racemase [EC 5.1.1.1], which catalyzes the interconversion between d- and l-alanine, was purified to homogeneity from the muscle of black tiger prawn Penaeus monodon. The isolated enzyme had a molecular mass of 44 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 90 kDa on gel filtration, indicating a dimeric nature of the enzyme. The enzyme was highly specific to d- and l-alanine and did not catalyze the racemization of other amino acids. K m values toward both d- and l-alanine were almost equal and considerably high compared with those of bacterial enzymes. The purified enzyme retained its activity in the absence of pyridoxal 5′-phosphate as a cofactor but carbonyl reagents inhibited the activity, suggesting the tightly binding of the cofactor to the enzyme protein. Several partial amino acid sequences of peptide fragments of the purified enzyme showed positive homologies from 52 to 76% with bacterial counterparts and a catalytic tyrosine residue of the bacterial enzyme was also retained in the prawn one, indicating alanine racemase gene is well conserved from bacteria to invertebrates.

Vertical transmission of gill-associated virus (GAV) in the black tiger prawn Penaeus monodon.

Chronic gill-associated virus (GAV) infection is endemic in Penaeus monodon broodstock captured from north-east Queensland in Australia and in farmed shrimp produced from these. We investigated the role of vertical transmission in perpetuating the high prevalence of these chronic GAV infections. Reverse transcription (RT)-nested PCR detected GAV in spermatophores and mature ovarian tissue from broodstock and in fertilized eggs and nauplii spawned from wild-fertilized females. In laboratory-reared P. monodon (> 12 mo old) that had a high mortality rate, RT-nested PCR detected GAV in male spermatophores at levels significantly higher than that detected in the lymphoid organ. By transmission electron microscopy (TEM), GAV virions were detected in spermatophore seminal fluid, but not sperm cells. Histological evidence of hypertrophied cell foci (spheroids) and TEM observation of GAV nucleocapsids and virions in spheroid cells was also found in 100% of lymphoid organs of approximately 1.2 g juvenile P. monodon reared in the laboratory from postlarvae collected from commercial hatcheries. Sequence analysis of PCR amplicons from parental P. monodon and fertilized eggs of artificially inseminated broodstock indicated that GAV associated with eggs can originate from both the male and female parents. Although the female GAV genotype was predominant in eggs, there was some dependence on infection levels in the male and female shrimp as indicated by RT-PCR. RT-nested PCR data on GAV levels in eggs, nauplii, protozoea and PL5 progeny of the artificial matings suggests that vertically transmitted virus is most probably associated with the egg surface.

Molecular cloning of a cDNA encoding a member of CHH/MIH/GIH family from Penaeus monodon and analysis of its gene structure

Abstract We report the nucleotide and deduced amino acid sequences of Pem-CMG peptide, a member of crustacean CHH/MIH/GIH peptide family, in black tiger prawn (Penaeus monodon). The 5′ and 3′ fragments of Pem-CMG cDNA were cloned by the method of rapid amplification of cDNA ends (RACE). The two fragments constitute a combined cDNA length of 593 bp with a 77 bp overlapping region. Sequence analysis reveals the presence of a 384 bp open reading frame which was subsequently cloned. The open reading frame encodes a precursor peptide that is comprised of 128 amino acids, with a putative processing site, KR. The mature peptide consists of 74 amino acid residues, the sequence of which is significantly homologous to those of the CHH/MIH/GIH family known from other crustaceans. Analysis of a genomic fragment of Pem-CMG reveals a single intron of 314 bp interrupting the coding sequence for the mature peptide. The presence of only one intron in Pem-CMG gene suggests that this gene is structurally different from the previously reported MIH gene of Charybdis feriatus and CHH-like gene of Metapenaeus ensis which possess two introns in their coding sequences.