Isolation and evaluation of dextral-specific and dextral-enriched cDNA clones as candidates for the handedness-determining gene in a freshwater gastropod, Lymnaea stagnalis
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The handedness of gastropods is genetically determined. The freshwater gastropod Lymnaea stagnalis is a normally dextral species, but contains minor sinistral populations. The gene responsible for handedness determination in this species is predicted to function maternally and specifically in the dextral-ovipositing snail. In this study, we used differential screening and cDNA subtraction to isolate eight “dextral genes” that are specific to, or enriched in, the dextral-ovipositing strains of L. stagnalis. These genes were promising candidates for the handedness-determining gene. In order to determine whether the true handedness-determining gene was among them, we tested for genetic correlations between the level of expression of each dextral gene and the handedness phenotype, i.e., the chirality of the next generation offspring, by using a collection of backcross F2 progeny of F1 offspring from crosses between dextral and sinistral strains. Although the present study could not identify the handedness-determining molecules, this approach appears to be promising for the isolation of such developmentally important genes.
KeywordsHandedness Gastropod Differential screening cDNA subtraction Genetic evaluation
We are grateful to Prof. Gary Freeman and Judith W. Lundelius (University of Texas) for their advice on the construction and maintenance of the laboratory snail stocks, and to Prof. Takahiro Asami (Shinshu University) for his kind assistance in obtaining the snails. We thank Dr. Miho Shimizu in our laboratory for her help with construction of the libraries. We also wish to thank other past and present members of our laboratory, especially Midori Kodama, Yuki Kadoishi, Keita Miyoshi, and Kota Yoshimatsu, for their efforts in maintaining the snail stocks. The sequences reported in this paper will appear in the DDBJ database with the respective accession numbers (DSC-1: AB159144, DSC-2: AB159145, DIC-1: AB159146, DIC-2: AB159147, DIC-3: AB159148, DEC-1: AB159149, DEC-2: AB159150, DEC-3: AB159151, RIC-1: AB159152, and YGSC-1: AB159153).
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