title: Transcriptome analysis in the midgut of the earthworm (Eisenia andrei) using expressed sequence tags.
abstract: In order to gain insight into the expression profiles of the earthworm midgut, we analyzed 1106 expressed sequence tags (ESTs) derived from the earthworm midgut cDNA library. Among the 1106 ESTs analyzed, 557 (50.4%) ESTs showed significant similarity to known genes and represented 229 unique genes of which 166 ESTs were singletons and 63 ESTs manifest as two or more ESTs. While 552 ESTs (49.9%) were sequenced only once, 230 ESTs (20.8%) appeared two to five times and 324 ESTs (29.3%) were sequenced more than five times. Considering this redundancy of expression, it is likely that the gene expression profile of the earthworm midgut would be polarized. The expression of globin-related proteins, including ferritin and linker chain, and fibrinolytic enzymes appeared to account for 10.1% and 4.7% of the total ESTs analyzed in this study, respectively. This suggests that the prime functions of the midgut in the earthworm would be associated with protein hydrolysis as well as globin formation. Among the recognized protein-coding genes, the gene category involved in protein synthesis appeared to be the largest one accounting for 15.6% of the expression in the midgut, followed by gene categories associated with energy (11.2%), homeostasis (10.8%), metabolism (3.6%), cytoskeleton (2.5%), and protein fate (1.4%). With regard to functional aspects, the most abundantly expressed genes were associated with respiratory pigment (10.1%), cellular respiration (8.6%), and fibrin hydrolysis (4.7%). In addition, we were able to identify novel ESTs in the earthworm, which were related to the innate immune system, including destabilase, a possible antagonist of transglutaminase.
authors.affiliation: Department of Life Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
authors.forename: Myung Sik
authors.initials: MS
authors.lastname: Lee
authors.forename: Sung Jin
authors.initials: SJ
authors.lastname: Cho
authors.forename: Eun Sik
authors.initials: ES
authors.lastname: Tak
authors.forename: Jong Ae
authors.initials: JA
authors.lastname: Lee
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Cho
authors.forename: Bum Joon
authors.initials: BJ
authors.lastname: Park
authors.forename: Chuog
authors.initials: C
authors.lastname: Shin
authors.forename: Dae Kyong
authors.initials: DK
authors.lastname: Kim
authors.forename: Soon Cheol
authors.initials: SC
authors.lastname: Park
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping / Q000379:methods; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000235:genetics* / Q000378:metabolism*; D020543:Proteome / Q000235:genetics* / Q000378:metabolism*; D017422:Sequence Analysis, DNA / Q000379:methods; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020543:Proteome; D014157:Transcription Factors