Twenty-one microsatellite loci from sea cucumber Apostichopus japonicus (Selenka, 1867), an endangered species on the IUCN Red List.

The sea cucumber Apostichopus japonicus-an endangered species on the IUCN Red List-is economically and ecologically important echinoderm species. Here we describe a set of 21 amplified microsatellites for A. japonicus isolated through biotinylated probes for hybridization and a library screening method, which were used to genotype an artificially propagated stock of sea cucumber offspring from Lianyungang City of China. The observed and expected heterozygosity at the population level ranged from 0.2083 to 0.1000 and 0.6260 to 0.9304, respectively. The number of alleles varied between 6 and 19, and none of the loci deviated significantly from the Hardy-Weinberg equilibrium (P < 0.01). These data might be useful in future analyses of sea cucumber genetic diversity, determination of genetic relationships, and the conservation of genetic resources.

Identification of a Proteus penneri isolate as the causal agent of red body disease of the cultured white shrimp Penaeus vannamei and its control with Bdellovibrio bacteriovorus.

Bacteriosis has become a major economic problem in the farming of the Pacific white shrimp Penaeus vannamei. However, no definitive data are available about Proteus penneri infection in cultured P. vannamei and its control. In this study, a virulent strain NC was isolated from diseased P. vannamei suffering from red body disease and identified as a P. penneri isolate through phylogenetic analysis and ATB 32GN system. A phylogenetic constructed tree using the neighbour-joining method identified the NC isolate as a P. penneri strain. In addition, Bdellovibrio bacteriovorus conferred significant protection against P. penneri: it exhibited significant bacteriolytic effects on the pathogenic P. penneri, had a wide prey range towards Proteus pathogens, and displayed a good protective efficacy on experimental P. penneri infection in P. vannamei. To the best of our knowledge, this is the first report of farmed P. vannamei infected with P. penneri and its control with B. bacteriovorus.

Genomic organization and promoter characterization of FcCTL, a C-type lectin-like protein in Fenneropenaeus chinensis.

Diseases caused by viruses are the greatest challenge to worldwide shrimp aquaculture. C-type lectins may play an important role in shrimp immunity. The gene encoding FcCTL, a C-type lectin-like protein, was isolated from Fenneropenaeus chinensis and characterized. This gene was composed of five exons spanning 2470 base pairs (bp). Intron 1 contained a possible promoter and many potential transcription factor binding sites, such as those for TATA binding protein, CREB, SRF, Ttk and three sites for HSFs. The 5'-flanking sequences (723 bp) of FcCTL contained typical CTF (CAAT box) and transcriptional regulatory elements, such as CF1, CF2-II and HSEs, observed in immunity-related genes in other arthropods. A series of FcCTL promoter sequences, especially the full-length promoter, generated an increase in luciferase expression relative to the promoter-less vector; furthermore, the expression of FcCTL was induced by heat shock and white spot syndrome virus (WSSV) challenge. These results extended our previous findings and provided insights into the molecular regulation of FcCTL gene expression, which would be helpful for shrimp viral disease control.

Discrepancy variation of dinucleotide microsatellite repeats in eukaryotic genomes.

To address whether there are differences of variation among repeat motif types and among taxonomic groups, we present here an analysis of variation and correlation of dinucleotide microsatellite repeats in eukaryotic genomes. Ten taxonomic groups were compared, those being primates, mammalia (excluding primates and rodentia), rodentia, birds, fish, amphibians and reptiles, insects, molluscs, plants and fungi, respectively. The data used in the analysis is from the literature published in the Journal of Molecular Ecology Notes. Analysis of variation reveals that there are no significant differences between AC and AG repeat motif types. Moreover, the number of alleles correlates positively with the copy number in both AG and AC repeats. Similar conclusions can be obtained from each taxonomic group. These results strongly suggest that the increase of SSR variation is almost linear with the increase of the copy number of each repeat motif. As well, the results suggest that the variability of SSR in the genomes of low-ranking species seem to be more than that of high-ranking species, excluding primates and fungi.