Isolation and characterization of a Japanese flounder clonal line, reversed, which exhibits reversal of metamorphic left-right asymmetry.
We have isolated a clonal line reversed (rev) of homozygous Japanese flounder through gynogenesis. The homozygous offspring gynogenetically produced from rev exhibited reversal of organization of the metamorphic L/R asymmetry such as the direction of eye-migration at a high frequency (20-30%). The molecular analysis using a left-specific marker pitx2 revealed that the embryonic L/R axis was ambiguously established: in more than half of rev embryos, pitx2 was expressed bilaterally in the lateral plate mesoderm (LPM). Previous studies in other animals demonstrated that ectopic pitx2 expression in the LPM could cause laterality defects of the visceral organs. Likewise, our results using rev imply that bilateral pitx2 expression could lead to randomization of the visceral organs. Coincidence of ectopic pitx2 expression and reversal of the direction of eye-migration in the population of rev offspring suggests that the rev locus is critical in specification of both the metamorphic and the visceral L/R asymmetries. However, reversal of the sidedness of the orientation of the visceral organs was not always accompanied by reversal of the direction of metamorphic eye-migration, suggesting that different mechanisms should be involved downstream of the rev locus in directing these two phases of asymmetric morphogenesis in the Japanese flounder.
Hashimoto
Hisashi
H
Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, 606-8502, Kyoto, Japan. hsshsmt@fra.affrc.go.jp
Mizuta
Akira
A
Okada
Nozomi
N
Suzuki
Tohru
T
Tagawa
Masatomo
M
Tabata
Kazuo
K
Yokoyama
Yoshihiro
Y
Sakaguchi
Morihiko
M
Tanaka
Masaru
M
Toyohara
Haruhiko
H
D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D003001:Cloning, Molecular; D016172:DNA Fingerprinting; D004625:Embryo, Nonmammalian; D005123:Eye / Q000254:growth & development; D005124:Eye Abnormalities / Q000235:genetics; D005260:Female; D005432:Flounder / Q000196:embryology / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006720:Homozygote; D007564:Japan; D008297:Male; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014781:Viscera / Q000033:anatomy & histology / Q000254:growth & development
D018398:Homeodomain Proteins; D014157:Transcription Factors