02432nas a2200277   4500008004100000022001400041245012900055210006900184260001300253300001100266490000800277520163700285653001201922653001601934653001101950653001501961653000901976653001201985653001501997653001702012653001402029100001902043700001802062700002202080856005202102       2014                        eng d  a1432-088600aTriploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex.0 aTriploid planarian reproduces truly bisexually with euploid game  c2014 Jun  a265-720 v1233 a<p>Although polyploids are common among plants and some animals, polyploidization often causes reproductive failure. Triploids, in particular, are characterized by the problems of chromosomal pairing and segregation during meiosis, which may cause aneuploid gametes and results in sterility. Thus, they are generally considered to reproduce only asexually. In the case of the Platyhelminthes Dugesia ryukyuensis, populations with triploid karyotypes are normally found in nature as both fissiparous and oviparous triploids. Fissiparous triploids can also be experimentally sexualized if they are fed sexual planarians, developing both gonads and other reproductive organs. Fully sexualized worms begin reproducing by copulation rather than fission. In this study, we examined the genotypes of the offspring obtained by breeding sexualized triploids and found that the offspring inherited genes from both parents, i.e., they reproduced truly bisexually. Furthermore, meiotic chromosome behavior in triploid sexualized planarians differed significantly between male and female germ lines, in that female germ line cells remained triploid until prophase I, whereas male germ line cells appeared to become diploid before entry into meiosis. Oocytes at the late diplotene stage contained not only paired bivalents but also unpaired univalents that were suggested to produce diploid eggs if they remained in subsequent processes. Triploid planarians may therefore form euploid gametes by different meiotic systems in female and male germ lines and thus are be able to reproduce sexually in contrast to many other triploid organisms.</p>
10aAnimals10aChromosomes10aFemale10aGerm Cells10aMale10aMeiosis10aplanarians10areproduction10aTriploidy1 aChinone, Ayako1 aNodono, Hanae1 aMatsumoto, Midori  uhttps://continenticola.myspecies.info/node/1766