DNA Sequencing and Bioinformatics Analysis of Clone pOr78 from the Species Specific Suppression Subtractive Hybridization Library Constructed from Endemic Wild Rice Species O. rhizomatis

Oryza rhizomatis is an endemic wild rice species in Sri Lanka with some unique characteristics of biotic and abiotic stress resistance. Hence characterization of desirable novel genes found in Oryza rhizomatis will be useful for transferring traits to commercial varieties. Therefore, in this study, a species-specific cDNA library was constructed from the wild rice species O. rhizomatis to isolate and characterize novel genes which are specifically present in this species but absent in cultivated rice (Oryza sativa). Forty recombinant clones were randomly selected from the cDNA SSH library and the inserts were sequenced. Sequence analysis of all forty clones indicated that the suppression and hybridization procedures in the library construction were successful as most of the clones have significant alignment with other wild rice species than O. sativa used as a reference cDNA for construction of subtraction library in this study. Therefore the genes which were specifically expressed in the wild rice species O. rhizomatis enriched in the SSH library. From this study it was possible to characterize O. rhizomatis nsLTP1 proteins (non specific Lipid Transfer Protein 1) super family AAI_LTSS which are found to be involved in control of pathogen attack related responses in plants.Int. J. Appl. Sci. Biotechnol. Vol 5(2): 133-140

Screening of Genes Specifically Expressed in Males ofFenneropenaeus chinensisand Their Potential as Sex Markers

The androgenic gland (AG), playing an important role in sex differentiation of male crustacean, is a target candidate to understand the mechanism of male development and to mine male-specific sex markers. An SSH library (designated as male reproduction-related tissues—SSH library, MRT-SSH library for short) was constructed using cDNA from tissues located at the basal part of the 5th pereiopods, including AG and part of spermatophore sac, as tester, and the cDNA from the basal part of the 4th pereiopods of these male shrimp as driver. 402 ESTs from the SSH library were sequenced and assembled into 48 contigs and 104 singlets. Twelve contigs and 14 singlets were identified as known genes. The proteins encoded by the identified genes were categorized, according to their proposed functions, into neuropeptide hormone and hormone transporter, RNA posttranscriptional regulation, translation, cell growth and death, metabolism, genetic information processing, signal transduction/transport, or immunity-related proteins. Eleven highly expressed contigs in the SSH library were selected for validation of the MRT-SSH library and screening sex markers of shrimp. One contig, specifically expressed in male shrimp, had a potential to be developed as a transcriptomic sex marker in shrimp.