Feeding aquatic animals with bacterial encapsulated heat-shock proteins (Hsps) is potentially a new method to combat vibriosis, an important disease affecting aquatic animals used in aquaculture. Food pellets comprised of shrimp and containing Escherichia coli overexpressing either DnaK-DnaJ-GrpE, the prokaryotic equivalents of Hsp70-Hsp40-Hsp20, or only DnaK were fed to juveniles of the white leg shrimp Penaeus vannamei, and protection against pathogenic Vibrio harveyi was determined. Maintaining pellets at different temperatures for varying lengths of time reduced the number of live adhering E. coli, as did contact with sea water, demonstrating that storage and immersion adversely affected bacterial survival and attachment to pellets. Feeding P. vannamei with E. coli did not compromise their survival, indicating that the bacteria were not pathogenic to shrimp. Feeding P. vannamei with pellets containing bacteria overproducing DnaK (approximately 60 cells g(-1) pellets) boosted P. vannamei survival twofold against V. harveyi, suggesting that DnaK plays a role in Vibrio tolerance. Pellets containing DnaK were effective in providing protection to P. vannamei for up to 2 weeks before loss of viability and that DnaK encapsulated by these bacteria enhanced shrimp resistance against Vibrio infection.
Adequate genetic information is essential for sustainable crustacean fisheries and aquaculture management. The commercially important orange mud crab, Scylla olivacea, is prevalent in Southeast Asia region and is highly sought after. Although it is a suitable aquaculture candidate, full domestication of this species is hampered by the lack of knowledge about the sexual maturation process and the molecular mechanisms behind it, especially in males. To date, data on its whole genome is yet to be reported for S. olivacea. The available transcriptome data published previously on this species focus primarily on females and the role of central nervous system in reproductive development. De novo transcriptome sequencing for the testes of S. olivacea from immature, maturing and mature stages were performed. A total of approximately 144 million high-quality reads were generated and de novo assembled into 160,569 transcripts with a total length of 142.2 Mb. Approximately 15-23% of the total assembled transcripts were annotated when compared to public protein sequence databases (i.e. UniProt database, Interpro database, Pfam database and Drosophila melanogaster protein database), and GO-categorised with GO Ontology terms. A total of 156,181 high-quality Single-Nucleotide Polymorphisms (SNPs) were mined from the transcriptome data of present study. Transcriptome comparison among the testes of different maturation stages revealed one gene (beta crystallin like gene) with the most significant differential expression-up-regulated in immature stage and down-regulated in maturing and mature stages. This was further validated by qRT-PCR. In conclusion, a comprehensive transcriptome of the testis of orange mud crabs from different maturation stages were obtained. This report provides an invaluable resource for enhancing our understanding of this species' genome structure and biology, as expressed and controlled by their gonads.