title: Two metallothionein genes from mud loach Misgurnus mizolepis (Teleostei; Cypriniformes): gene structure, genomic organization, and mRNA expression analysis.
abstract: Two metallothionein genes, MLMT-IA and MLMT-IB, were isolated and characterized from the mud loach Misgurnus mizolepis (Teleostei; Cypriniformes). For these MTs, we determined a tandem "tail-to-head" genomic organizational pattern, identified conserved genomic features, showed high sequence identities in the coding regions, and examined the closest phylogenetic affiliation, suggesting their divergence by a recent gene duplication event. However, the 5'-flanking upstream regions in MLMT-IA and MLMT-IB exposed large differences in the composition and distribution patterns of various transcription factor binding motifs, especially regarding the organization of the metal response element clusters. Real-time RT-PCR assays showed that mRNA levels of both MLMT-IA and MLMT-IB isoforms were variable among tissues and the ratios between them were also variable across tissues, although the MLMT-IA was always predominant in every adult tissue tested. We also found that the MLMT-IA and MLMT-IB mRNA expression levels were regulated dynamically during embryonic and larval development stages, in which the basal expression level of MLMT-IA was also consistently higher than that of MLMT-IB. Upon acute in vivo metal exposure to cadmium, chromium, copper, iron, manganese, nickel, or zinc at 5 microM for 48 h, the transcriptional modulations of MLMT-IA and MLMT-IB were quite different from each other and the type of response was affected significantly by the kind of metals and tissues.
authors.affiliation: Department of Aquaculture, Pukyong National University, Busan 608-737, Republic of Korea.
authors.forename: Young Sun
authors.initials: YS
authors.lastname: Cho
authors.forename: Sang Yoon
authors.initials: SY
authors.lastname: Lee
authors.forename: Keun-Yong
authors.initials: KY
authors.lastname: Kim
authors.forename: Yoon Kwon
authors.initials: YK
authors.lastname: Nam
mesh_terms: D024506:5' Flanking Region; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003531:Cypriniformes / Q000196:embryology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005786:Gene Expression Regulation; D008668:Metallothionein / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D008670:Metals; D020033:Protein Isoforms; D012333:RNA, Messenger; D008668:Metallothionein