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At least 739 records · Page 41Linked to original sources

Purification and characterization of infectious myonecrosis virus of penaeid shrimp.

The causative agent of myonecrosis affecting cultured Penaeus vannamei in Brazil was demonstrated to be a virus after purification of the agent from infected shrimp tissues. Purified viral particles were injected into specific pathogen-free P. vannamei, resulting in a disease that displayed the same characteristics as those found in the original shrimp used for purification. The virus was named infectious myonecrosis virus (IMNV). The viral particles were icosahedral in shape and 40 nm in diameter, with a buoyant density of 1.366 g ml(-1) in caesium chloride. The genome consisted of a single, double-stranded (dsRNA) molecule of 7560 bp. Sequencing of the viral genome revealed two non-overlapping open reading frames (ORFs). The 5' ORF (ORF 1, nt 136-4953) encoded a putative RNA-binding protein and a capsid protein. The coding region of the RNA-binding protein was located in the first half of ORF 1 and contained a dsRNA-binding motif in the first 60 aa. The second half of ORF 1 encoded a capsid protein, as determined by amino acid sequencing, with a molecular mass of 106 kDa. The 3' ORF (ORF 2, nt 5241-7451) encoded a putative RNA-dependent RNA polymerase (RdRp) with motifs characteristic of totiviruses. Phylogenetic analysis based on the RdRp clustered IMNV with Giardia lamblia virus, a member of the family Totiviridae. Based on these findings, IMNV may be a unique member of the Totiviridae or may represent a new dsRNA virus family that infects invertebrate hosts.

Amino Acid Sequence↗

Multiple origins of eusociality among sponge-dwelling shrimps (Synalpheus).

As the most extreme expression of apparent altruism in nature, eusociality has long posed a central paradox for behavioral and evolutionary ecology. Because eusociality has arisen rarely among animals, understanding the selective pressures important in early stages of its evolution remains elusive. Employing a historical approach to this problem, we used morphology and DNA sequences to reconstruct the phylogeny of 13 species of sponge-dwelling shrimps (Synalpheus) with colony organization ranging from asocial pair-bonding through eusociality. We then used phylogenetically independent contrasts to test whether sociality was associated with evidence of enhanced competitive ability, as suggested by hypotheses invoking an advantage of cooperation in crowded habitats. The molecular, morphological, and combined data each strongly supported three independent origins of monogynous, multigenerational (eusocial) colony organization within this genus. Phylogenetically independent contrasts confirmed that highly social taxa, with strong reproductive skew, have significantly higher relative abundance within the host sponge than do less social taxa, a result that was robust to uncertainty in tree topology and varying models of character change. A similar tendency for highly social species to share their sponge with fewer congener species was suggestive, but not significant. Because unoccupied habitat appears to be limiting for many sponge-dwelling shrimp species, these data are consistent with hypotheses that cooperative social groups enjoy a competitive advantage over less organized groups or individuals, where independent establishment is difficult, and that enemy pressure is of central importance in the evolution of animal sociality.

Animals↗

Development of polymorphic expressed sequence tag-derived microsatellites for the extension of the genetic linkage map of the black tiger shrimp (Penaeus monodon).

In this study, microsatellite markers were developed for the genetic linkage mapping and breeding program of the black tiger shrimp Penaeus monodon. A total of 997 unique microsatellite-containing expressed sequence tags (ESTs) were identified from 10 100 EST sequences in the P. monodon EST database. AT-rich microsatellite types were predominant in the EST sequences. Homology searching by the blastn and blastx programs revealed that these 997 ESTs represented 8.6% known gene products, 27.8% hypothetical proteins and 63.6% unknown gene products. Characterization of 50 markers on a panel of 35-48 unrelated shrimp indicated an average number of alleles of 12.6 and an average polymorphic information content of 0.723. These EST microsatellite markers along with 208 other markers (185 amplified fragment length polymorphisms, one exon-primed intron-crossing, six single strand conformation polymorphisms, one single nucleotide polymorphism, 13 non-EST-associated microsatellites and two EST-associated microsatellites) were analysed across the international P. monodon mapping family. A total of 144 new markers were added to the P. monodon maps, including 36 of the microsatellite-containing ESTs. The current P. monodon male and female linkage maps have 47 and 36 linkage groups respectively with coverage across half the P. monodon genome.

Animals↗

Susceptibility of the brine shrimp Artemia and its pathogen Vibrio parahaemolyticus to chlorine dioxide in contaminated sea-water.

Adults and nauplii of the brine shrimp, Artemia, together with Vibrio parahaemolyticus, were placed in sewage-contaminated sea-water which had been treated with chlorine dioxide (Hallox E-100TM) to test its potential as a disinfectant for salt water aquaculture. The nauplii were very susceptible to low concentrations of chlorine dioxide (47 micrograms/l Cl-), but the adults were slightly more resistant. Sterile sea-water treated with lower concentrations of chlorine dioxide (less than 47 micrograms/l Cl-) had no effect on the shrimp, but inhibited the growth of V. parahaemolyticus. In sewage-contaminated sea-water, chlorine dioxide levels of 285-2850 micrograms/l, necessary for the inactivation of V. parahaemolyticus and any native bacteria, destroyed the Artemia culture. Hallox E-100TM persisted in sea-water for 18 h, but later decayed. We conclude that: (i) Artemia nauplii are a sensitive and convenient test-organism to determine low concentrations of chlorine dioxide in sea-water; (ii) chlorine dioxide is efficient for controlling V. parahaemolyticus in sea-water; and (iii) chlorine dioxide should be further evaluated as a potential disinfectant for aquaculture, but, for higher organisms than Artemia.

Animals↗

Fusarium incarnatum isolated from black tiger shrimp, Penaeus monodon Fabricius, with black gill disease cultured in Vietnam.

Fusarium incarnatum was isolated from gill lesions of cultured black tiger shrimp, Penaeus monodon, in every crop during 2000-2002 in Nghe An province, Vietnam. Infected shrimps showed typical signs of black gill disease and mortalities about a month prior to harvest. Detailed morphological examinations, as well as molecular phylogenic analyses based on partial nucleotide sequences of ribosomal DNA, were made on the isolates. An artificial infection of kuruma prawn, Penaeus japonicus, using two selected isolates was also conducted and their pathogenicity determined.

Animals↗

A single-step multiplex PCR for simultaneous detection of white spot syndrome virus and infectious hypodermal and haematopoietic necrosis virus in penaeid shrimp.

White spot syndrome virus (WSSV) and infectious hypodermal and haematopoietic necrosis virus (IHHNV) are the major viral pathogens of penaeid shrimp worldwide (Lightner & Redman 1998). Litopenaeus vannamei was introduced into China from the Americas, and quickly became widely cultured. Following its introduction, both IHHNV and WSSV have become important pathogens of cultured penaeid shrimp and have had a huge impact on the culture industry in China in recent years.

Animals↗

Biogeographic history of an Australian freshwater shrimp, Paratya australiensis (Atyidae): the role life history transition in phylogeographic diversification.

The widespread distribution of the freshwater shrimp Paratya australiensis in eastern Australia suggests that populations of this species have been connected in the past. Amphidromy is ancestral in these shrimps, although many extant populations are known to be restricted to freshwater habitats. In this study, we used a fragment of the cytochrome c oxidase I mitochondrial DNA (mtDNA) gene to examine diversity within P. australiensis and to assess the relative importance of amphidromy in its evolutionary history. We hypothesized that if transitions from an amphidromous to a freshwater life history were important, then we would find a number of divergent lineages restricted to single or groups of nearby drainages. Alternatively, if amphidromy was maintained within the species historically, we expected to find lineages distributed over many drainages. We assumed that the only way for divergence to occur within amphidromous lineages was if dispersal was limited to between nearby estuaries, which, during arid periods in the earth's history, became isolated from one another. We found nine highly divergent mtDNA lineages, estimated to have diverged from one another in the late Miocene/early Pliocene, when the climate was more arid than at present. Despite this, the geographic distribution of lineages and haplotypes within lineages did not support the notion of a stepping-stone model of dispersal between estuaries. We conclude that the extensive divergence has most likely arisen through a number of independent amphidromy-freshwater life history transitions, rather than via historical isolation of amphidromy populations. We also found evidence for extensive movement between coastal and inland drainages, supporting the notion that secondary contact between lineages may have occurred as a result of drainage rearrangements. Finally, our data indicate that P. australiensis is likely a complex of cryptic species, some of which are widely distributed, and others geographically restricted.

Animal Migration↗

B- and T-cell epitopes of tropomyosin, the major shrimp allergen.

The major crustacean allergen characterized from different species of shrimp is the muscle protein tropomyosin. Two shared epitopes corresponding to 47-63 and 150-158 of the deduced amino-acid sequence of the brown shrimp, M. ensis, were identified as IgE-binding B-cell epitopes. A 21-mer peptide spanning the amino-acid residues 261-281 was identified as a putative T-cell epitope capable of reducing ongoing tropomyosin-specific IgG and IgE responses in a mouse model. These observations suggest that peptide immunotherapy may also be effective in the treatment of food hypersensitivity.

Allergens↗

Levels of inbreeding depression over seven generations of selfing in the androdioecious clam shrimp, Eulimnadia texana.

Androdioecy (mixtures of males and hermaphrodites) is a rare mating system in both plants and animals. Theory suggests that high levels of inbreeding depression can maintain males in androdioecious populations if hermaphrodites commonly self-fertilize. However, if inbreeding depression (delta) can be 'purged' from selfing populations, maintaining males is more difficult. In the androdioecious clam shrimp, Eulimnadia texana, delta is estimated to be as high as 0.7. Previous work suggests that this high level is maintained in the face of high levels of inbreeding due to an associative overdominance of fitness-related loci with the sex-determining locus. Such associative overdominance would make purging of inbreeding depression difficult to impossible. The current experiment was designed to determine if delta can be purged in these shrimp by tracking fitness across seven generations in selfing and outcrossing treatments. Evidence of purging was found in one of four populations, but the remaining populations demonstrated a consistent pattern of delta across generations. Although the experimental design allowed ample opportunity for purging, the majority of populations were unable to purge their genetic load. Therefore, delta in this species is likely due to associative overdominance caused by deleterious recessive alleles linked to the sex determining locus.

Analysis of Variance↗

Isolation and characterization of multilayered sheath membrane rich in glucocerebroside from shrimp ventral nerve.

A membrane fraction rich in glucocerebroside was isolated from homogenates of ventral nerves of pink shrimp (Penaeus duorarum) by sucrose gradient centrifugation. The membrane fraction was observed at 0.15 M sucrose and was rich in lipids (lipid/protein ratio approximately 15:1). Electron microscopy showed that the fraction was derived from myelin-like multilayered glial membrane ensheathing axons, which has morphological similarities to myelin. Most of the lipids in shrimp nerve, including glucocerebroside, sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and ethanolamine-plasmalogen, as well as cholesterol, appeared to be concentrated in this fraction. The fatty acids of these phospholipids were exclusively saturated or monounsaturated with C14-C26 chain lengths. The aldehyde moiety of plasmalogens contained only saturated C14-C18 carbon chains. Like glucocerebrosides, the sphingoid base of sphingomyelin consisted mainly of C14-C16 sphingenines and sphinganines, but they also contained significant amounts of C19 and C20 sphinganines. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins in this fraction showed several bands in the 23,000-85,000 Mr range. Radioimmunoassay, however, did not show cross-reactivity with antibodies to myelin basic protein. The functional role of this membrane in relation to mammalian myelin is discussed.

Animals↗

Genetic heterogeneity among Vibrio alginolyticus isolated from shrimp farms by PCR fingerprinting.

AIMS: To study the strain variability among Vibrio alginolyticus isolates from different sources by insertion sequence-targeted PCR fingerprinting and whole cell protein profile analysis. METHODS AND RESULTS: Eleven strains of V. alginolyticus were isolated from seven different sources including healthy, infected, farm-reared and wild shrimps. Following biochemical characterization, the isolates were analysed by PCR fingerprinting and whole cell protein analysis by SDS-PAGE. The strains were genetically different irrespective of the sources of isolation. CONCLUSIONS: Strain variation exists in V. alginolyticus isolates obtained even from the same source, and PCR fingerprinting is a simple and efficient method in identifying strain-specific variations among the different isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Vibrio alginolyticus is implicated in severe vibriosis of marine aquaculture systems although many strains are avirulent and could be used as probiotic strains. As a wide variation exists among this species, differentiating the harmful and beneficial strains would help in finding ways of controlling the infections by eliminating harmful shrimp pathogenic vibrios.

Animals↗

The use of probiotics in shrimp aquaculture.

Shrimp aquaculture, as well as other industries, constantly requires new techniques in order to increase production yield. Modern technologies and other sciences such as biotechnology and microbiology are important tools that could lead to a higher quality and greater quantity of products. Feeding and new practices in farming usually play an important role in aquaculture, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice of many fish and shrimp feed manufacturers and farmers. Probiotics, as 'bio-friendly agents' such as lactic acid bacteria and Bacillus spp., can be introduced into the culture environment to control and compete with pathogenic bacteria as well as to promote the growth of the cultured organisms. In addition, probiotics are nonpathogenic and nontoxic microorganisms without undesirable side-effects when administered to aquatic organisms. These strains of bacteria have many other positive effects, which are described in this article.

Animals↗

Occupational dermatitis in shrimp peelers.

A total of 110 female shrimp production workers from 2 factories were invited to participate in an investigation of occupational skin problems. A questionnaire was filled in by 94 workers and 24 (20.2%) claimed skin problems due to working conditions. In 7 (6%), a diagnosis of occupational dermatitis of the hands was made. In 2, there were strongly positive reactions to shrimp. 5 had negative tests but a positive history of occupational provocation.

Decapoda↗

N-acetyltransferase, hydroxyindole-O-methyltransferase and melatonin in the optic lobes of the giant tiger shrimp Penaeus monodon.

The activities of the enzymes N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) and the hormone melatonin were studied in the optic lobe of the subadult giant tiger shrimp Penaeus monodon. Compared with the level in other species, a relatively high level of NAT activity that was temperature- and pH-dependent were observed. The NAT enzyme had a relatively high maximum velocity (Vmax, 100 pmol/hr/micrograms protein) and low Michaelis constant (Km, 22 microM), when tryptamine is used as substrate. In contrast to the high level of NAT activity, HIOMT activity and melatonin levels were low in the optic lobe of the giant tiger shrimp. Sex differences in the levels of NAT activity and melatonin, which are observed in a freshwater species Macrobrachium rosenbergii, were not noticeable in the saltwater species P. monodon, at least not when they were in their subadult stage.

Acetylserotonin O-Methyltransferase↗

In situ source level and source position estimates of biological transient signals produced by snapping shrimp in an underwater environment.

Biological transient signals produced by snapping shrimp are sensed underwater by a wide aperture array. The instantaneous range and bearing of the source position of each snap is estimated along with a source level equal to the peak-to-peak amplitude of the pressure impulse generated by the snap at a standard distance of 1 m from its point of origin. For a sample of 1000 snaps recorded in Sydney Harbour, the distribution of peak-to-peak sound pressure levels has a mean value of 187 dB (re 1 microPa) and an interquartile range of 185-189 dB (re 1 microPa). Plotting the Cartesian coordinates of the source positions of the biological transient signals over a period of time maps the two-dimensional spatial distribution of the local snapping shrimp population. The principal habitat is found to be geocoincident with a 120-m-long wharf, the closest point of which is 60 m from the middle of the receiving array. The passive ranging performance of the wide aperture array is evaluated by generating mechanical transient signals at selected positions along the wharf. Precise estimates of the relative times-of-arrival of the acoustic wavefronts lead to source range and bearing estimates with standard deviations of only 0.1 m and 0.005 degrees (respectively), in agreement with theoretical predictions.

Animal Communication↗

Biophysics. For certain shrimp, life's a snap.

On page 2114 of this issue, physicists report that a collapsing bubble outside the claw of the snapping shrimp Alpheus heterochaelis causes its characteristic clack. According to this new study, A. heterochaelis clamps its claw so rapidly that a water jet gushing from the claw first loses and then gains pressure, causing an air bubble in the jet to swell and collapse with a pronounced "snap!" The imploding bubble generates shock waves that stun nearby prey and ward off other shrimp, who have learned to keep their distance.

Air↗

Application of ribotyping for differentiating Vibrio cholerae non-O1 isolated from shrimp farms in Thailand.

A collection of 143 Vibrio cholerae non-O1 strains isolated from shrimp farms in Thailand were characterized and grouped by ribotyping. Sixty-four ribotypes were distinguished following digestion of chromosomal DNA with the restriction enzyme BglI, and the reproducibility of the method was 100%. There was no correlation between specific ribotype distributions and the locations of the shrimp farms. Ribotype similarity was examined by cluster analysis, and two main groups with 10 and 54 ribotypes, respectively, were found. Correlation between ribotype and O-antigen expression was shown to exist among those isolates tested. Ribotyping appears to be a suitable method for differentiating environmental V. cholerae non-O1 strains, and comparison of ribotype patterns showed a high degree of genetic divergence within V. cholerae non-O1.

Animals↗

Bacteriological survey of the frozen prepared foods industry. II. Frozen breaded raw shrimp.

During inspection of 21 frozen breaded raw shrimp processors, 861 finished product units (retail packages) and 778 line samples were collected and analyzed bacteriologically. The bacteriological results for the finished product samples collected in plants with poor and good sanitary controls are presented and compared. The samples consisted of 4 to 38 units (retail packages) of the finished product as offered for sale by the processors. Frozen raw breaded shrimp collected from plants operating under good conditions of sanitation had the following bacterial contents: 85% of the samples had an average (geometric) aerobic plate count of less than 1,000,000 per gram; all of the samples had an average (geometric) most probable number of less than 1,000 coliforms per g; 81% of the samples contained less than 20% Escherichia coli-positive units; 57% of the total number of units in 0.1-g portions were negative for coagulase-positive staphylococci, and 95% of the units had less than 1,000 coagulase-positive staphylococci per gram.

Escherichia coli↗