title: Analysis of expressed sequence tags and characterization of a novel gene, Slmg7, in the midgut of the common cutworm, Spodoptera litura.
abstract: BACKGROUND
  Out of total 3,081 assembled expressed sequence tags (ESTs) sequences representing 6,815 high-quality ESTs identified in three cDNA libraries constructed with RNA isolated from the midgut of Spodoptera litura, 1,039 ESTs showed significant hits and 1,107 ESTs did not show significant hits in BLAST searches. It is of interest to clarify whether or not these ESTs that did not show hits function in S. Litura.
  
  
  RESULTS
  Twenty "no-hit" ESTs containing at least one putative open reading frame were selected for further expression analysis. The results from northern blot analysis showed that six of the selected ESTs are expressed in the larval midgut of this insect at different levels, suggesting that these ESTs represent true mRNA products, whereas the other 14 ESTs could not be detected. Homologues of the four larval midgut-predominant genes (Slmg2, Slmg7, Slmg9 and Slmg17) were detected in the genomes of other lepidopteran insects but not in Drosophila melanogaster. A novel gene, Slmg7, is expressed at a high level specifically in the midgut during each of the larval stages. Slmg7 is a single copy gene and encodes a 143-amino acids protein. The SLMG7 protein was localized to the cytoplasm of Spli-221 cells.
  
  
  CONCLUSIONS
  Six ESTs from the no hit list are transcribed into mRNA and are mainly expressed in the midgut of S. litura. Slmg7 is a novel gene that is localized to the cytoplasm.
authors.affiliation: Guangdong Provincial Key Lab of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China.
authors.forename: Wen-yin
authors.initials: WY
authors.lastname: He
authors.forename: Zhong-chen
authors.initials: ZC
authors.lastname: Rao
authors.forename: Dao-hua
authors.initials: DH
authors.lastname: Zhou
authors.forename: Si-chun
authors.initials: SC
authors.lastname: Zheng
authors.forename: Wei-hua
authors.initials: WH
authors.lastname: Xu
authors.forename: Qi-li
authors.initials: QL
authors.lastname: Feng
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D019295:Computational Biology; D020224:Expressed Sequence Tags; D041981:Gastrointestinal Tract / Q000378:metabolism; D015723:Gene Library; D019476:Insect Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D018411:Spodoptera / Q000235:genetics* / Q000254:growth & development
chemical_list: D019476:Insect Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins