Title: Insight into the Genes of Lygus through ESTs Author
Submitted to: Mid-South Entomologists online journal
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2007
Publication Date: January 15, 2008
Citation: Allen, M.L. 2008. Insight into the Genes of Lygus through ESTs. Mid-South Entomologists online journal. Technical Abstract: All of an organism’s genes are contained within the genome, which is composed of DNA. The genes that are being actively used by the organism are transcribed into RNA. At a given time of development, or in a specific tissue, the RNA present makes up the transcriptome. Some transcribed RNAs are translated into proteins; at a given time of development, or in a specific tissue, the proteins present make up the proteome. While each nucleus of each cell in every stage of the insect contains at least one complete set of genomic DNA, the expressed genes (those transcribed into RNA and translated into proteins) differ in the egg, nymph, and adult stages, and between the sexes in adults and preadults. Male nymphs were collected fresh and total RNA was extracted. Each nymph yielded around 10 micrograms of RNA. When this RNA was further purified into polyA RNA, about 2% (200 ng) of the RNA sample remained. From this, a cDNA library was constructed. Sequencing was performed by the USDA ARS in Stoneville, MS. Sequences were analyzed by comparison with the NCBI (National Center for Biotechnology Information, at the website http://www.ncbi.nlm.nih.gov) BLAST algorithms. This study (Allen 2007) revealed many previously unknown genes for an increasingly important pest. Two hundred and seventy-two unique ESTs were generated, 48% of which could be identified as highly similar to other sequences. The average sequence length was 768 bases, with only eleven ESTs having a length less than 300 bases. Sequences less than 200 bases were not deposited as ESTs. Sequences that could be identified with some probability were categorized into six groups. Transcription and translation (10% of provisionally identified sequences) including ten ribosomal proteins. Cellular metabolism and physiological process sequences (15%). Structural and cytoskeletal sequences (7%). Sequences associated with feeding and digestion (4%). Mitochondrial sequences (4%). Sequences homologous to genes for which a function was not identified (8%). The male nymph ESTs were used to identify enzymes used to break down plant cell walls, polygalacturonases (Allen et al. accepted). Additional ESTs from adult females are being deposited. Genes that are specific to males and females will be identified. I hope to identify genes associated with pigments and cuticle synthesis. Additional ESTs derived from salivary glands, and from developing embryos, will be cloned and sequenced. Salivary gland genes will be used to design plant protection tools to combat Lygus and other sucking pests. Allen ML. 2007. Expressed sequenced tags from Lygus lineolaris (Hemiptera: Miridae), the tarnished plant bug. Genetics and Molecular Research 6: 206-213. Allen ML, Mertens JA. accepted. Molecular cloning and expression of three polygalacturonase cDNAs from the tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae). Journal of Insect Science.