title: Diaphanous gene mutation affects spiral cleavage and chirality in snails.
abstract: L-R (left and right) symmetry breaking during embryogenesis and the establishment of asymmetric body plan are key issues in developmental biology, but the onset including the handedness-determining gene locus still remains unknown. Using pure dextral (DD) and sinistral (dd) strains of the pond snail Lymnaea stagnalis as well as its F2through to F10backcrossed lines, the single handedness-determining-gene locus was mapped by genetic linkage analysis, BAC cloning and chromosome walking. We have identified the actin-related diaphanous gene Lsdia1 as the strongest candidate. Although the cDNA and derived amino acid sequences of the tandemly duplicated Lsdia1 and Lsdia2 genes are very similar, we could discriminate the two genes/proteins in our molecular biology experiments. The Lsdia1 gene of the sinistral strain carries a frameshift mutation that abrogates full-length LsDia1 protein expression. In the dextral strain, it is already translated prior to oviposition. Expression of Lsdia1 (only in the dextral strain) and Lsdia2 (in both chirality) decreases after the 1-cell stage, with no asymmetric localization throughout. The evolutionary relationships among body handedness, SD/SI (spiral deformation/spindle inclination) at the third cleavage, and expression of diaphanous proteins are discussed in comparison with three other pond snails (L. peregra, Physa acuta and Indoplanorbis exustus).
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.|Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.|JST ERATO-SORST Kuroda Chiromorphology Project, Meguro-ku, Tokyo, Japan.|Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan.|Department of Applied Biological Science, Graduate School of Science and Technology, Tokyo University of Science, Noda-shi, Chiba, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Kuroda
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.|JST ERATO-SORST Kuroda Chiromorphology Project, Meguro-ku, Tokyo, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujikura
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.|JST ERATO-SORST Kuroda Chiromorphology Project, Meguro-ku, Tokyo, Japan.|Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Abe
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.|JST ERATO-SORST Kuroda Chiromorphology Project, Meguro-ku, Tokyo, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hosoiri
authors.affiliation: Department of Molecular Biology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Asakawa
authors.affiliation: JST ERATO-SORST Kuroda Chiromorphology Project, Meguro-ku, Tokyo, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Shimizu
authors.affiliation: Department of Applied Biological Science, Graduate School of Science and Technology, Tokyo University of Science, Noda-shi, Chiba, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Umeda
authors.affiliation: Department of Applied Biological Science, Graduate School of Science and Technology, Tokyo University of Science, Noda-shi, Chiba, Japan.
authors.forename: Futaba
authors.initials: F
authors.lastname: Ichikawa
authors.affiliation: Department of Applied Biological Science, Graduate School of Science and Technology, Tokyo University of Science, Noda-shi, Chiba, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D060105:Animal Shells / Q000502:physiology; D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D002874:Chromosome Mapping; D004625:Embryo, Nonmammalian / Q000166:cytology; D005260:Female; D016368:Frameshift Mutation; D018507:Gene Expression Regulation, Developmental; D008195:Lymnaea / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D008297:Male; D011506:Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism
chemical_list: D011506:Proteins