title: A hypothesis of ploidy elevation by formation of a female pronucleus in the androgenetic clam Corbicula fluminea in the Tone River estuary, Japan.
abstract: We propose a hypothesis of ploidy elevation in the androgenetic clam Corbicula fluminea, based on an abnormal process of fertilization in clams collected at the Tone River, Ibaraki Prefecture, Japan. Most eggs showed androgenesis, that is, extrusion of all maternal chromosomes as two polar bodies during the first meiotic division. Most eggs did not form a female pronucleus, but only a male pronucleus. However, some eggs proceeded to the second meiosis and formed both a female and a male pronucleus. The formation of the female pronucleus suggests the hypothesis that ploidy elevation in androgenetic clams may have occurred by aberrant meiosis due to an altered orientation of the meiotic spindle.
authors.affiliation: Faculty of Bioresources, Mie University, Tsu, Japan. komaru@bio.mie-u.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Komaru
authors.forename: Atsuko
authors.initials: A
authors.lastname: Kumamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kato
authors.forename: Ryo
authors.initials: R
authors.lastname: Ishibashi
authors.forename: Mayu
authors.initials: M
authors.lastname: Obata
authors.forename: Takao
authors.initials: T
authors.lastname: Nemoto
mesh_terms: D000818:Animals; D049874:Corbicula / Q000196:embryology / Q000235:genetics*; D005260:Female; D007564:Japan; D008297:Male; D008540:Meiosis / Q000502:physiology*; D011003:Ploidies; D013997:Time Factors