title: Production of diploid and triploid offspring by inbreeding of the triploid planarian Dugesia ryukyuensis.
abstract: Triploidy has generally been considered to be an evolutionary dead end due to problems of chromosomal pairing and segregation during meiosis. Thus, the formation of tetraploids and diploids from triploid types is a rare phenomenon. In the present study, we demonstrated that inbreeding of the triploid planarian Dugesia ryukyuensis resulted in both diploid and triploid offspring in nature. In the triploids of D. ryukyuensis, chiasmata between homologous chromosomes were observed in both female and male germ lines. This result suggests that both diploid and triploid offspring of this species are produced bisexually by zygotic fusion between sperm and eggs. Hence, this phenomenon may be a novel mechanism in planarian for escaping the triploid state.
authors.affiliation: Department of Biosciences and Informatics, Keio University, Hiyoshi 3-14-1, Kouhoku-ku, Yokohama 223-8522, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ishizu
authors.forename: Sachiko
authors.initials: S
authors.lastname: Arioka
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Padilla Cabrera
authors.forename: Motonori
authors.initials: M
authors.lastname: Hoshi
authors.forename: Midori
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics; D004247:DNA; D004171:Diploidy; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D007178:Inbreeding; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D008938:Mitosis; D010063:Ovum; D010932:Planarians / Q000166:cytology / Q000235:genetics*; D011123:Polyploidy; D012098:Reproduction
chemical_list: D004247:DNA