Two metallothionein genes from mud loach Misgurnus mizolepis (Teleostei; Cypriniformes): gene structure, genomic organization, and mRNA expression analysis.
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.
Cho
Young Sun
YS
Department of Aquaculture, Pukyong National University, Busan 608-737, Republic of Korea.
Lee
Sang Yoon
SY
Kim
Keun-Yong
KY
Nam
Yoon Kwon
YK
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
D008670:Metals; D020033:Protein Isoforms; D012333:RNA, Messenger; D008668:Metallothionein