@article {1766, title = {Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex.}, journal = {Chromosoma}, volume = {123}, year = {2014}, month = {2014 Jun}, pages = {265-72}, abstract = {

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.

}, keywords = {Animals, Chromosomes, Female, Germ Cells, Male, Meiosis, planarians, reproduction, Triploidy}, issn = {1432-0886}, doi = {10.1007/s00412-013-0449-2}, author = {Chinone, Ayako and Nodono, Hanae and Matsumoto, Midori} } @article {1715, title = {The impairments of neoblast division in regenerating planarian Polycelis felina (Daly.) caused by in vitro treatment with cadmium sulfate}, journal = {Toxicol In Vitro}, volume = {18}, year = {2004}, month = {2004 Feb}, pages = {99-107}, abstract = {

The effects of cadmium sulfate on the neoblast mitotic activity in regenerating planarian Polycelis felina (Daly.) were investigated. Mitotic abnormalities and chromosomal aberrations were evaluated after 6-h treatment and 24-h recovery period. The blastema were fixed, and examined cytologically through routine lactoorceine squash preparations. Mitotic indices were also determined. Cadmium sulfate induced a dose-dependent decrease in neoblast mitotic activity, accompanied with disturbances in distribution of cells over mitotic phases. Different cytological abnormalities with varying frequency were observed. Marked mitotic depression was concentration-dependent. Toxic effects of cadmium in regenerating planarian were mainly associated with mitotic spindle disturbances. Immediately after treatment mitotic abnormalities were prevalent over chromosomal and C-mitosis was the most prominent one. After 24-h recovery period a prevalence of mitotic over chromosomal aberrations was still present in animals treated with two higher concentrations of cadmium sulfate. However, the proportions of cells with chromosome stickiness in all treated animals were significantly increased compared to their post-treatment values. Observed mitotic impairments could be related to mitotic arrest contributing to retardations and delays, especially in animals treated with the highest concentration tested. The results obtained indicated usefulness of short term invertebrate assays as an alternative to in vitro pre-screening of toxic chemicals.

}, keywords = {Animals, Biological Assay, Cadmium Compounds, Cell Division, Chromosome Aberrations, Croatia, Dose-Response Relationship, Drug, Drug Evaluation, Preclinical, Female, Forecasting, Mitosis, Mitotic Index, Mortality, Oxygen Consumption, planarians, regeneration, Sulfates, Survival, Time Factors}, issn = {0887-2333}, author = {Kalafati{\'c}, M and Kopjar, N and Besendorfer, V} } @article {1711, title = {Genesis, composition and fate of cortical granules in the eggs of Polycelis nigra (Turbellaria, Tricladida).}, journal = {J Ultrastruct Res}, volume = {50}, year = {1975}, month = {1975 Feb}, pages = {277-83}, keywords = {Animals, Cytoplasmic Granules, Female, Fertilization, Glycoproteins, Golgi Apparatus, Histocytochemistry, Microscopy, Electron, Ovum, Polysaccharides, Proteins, Turbellaria}, issn = {0022-5320}, author = {Gremigni, V and Domenici, L} } @article {1709, title = {Terrestrial turbellarians (Tricladida: Bipaliidae) as pseudoparasites of man.}, journal = {J Parasitol}, volume = {58}, year = {1972}, month = {1972 Jun}, pages = {444-6}, keywords = {Aged, Diagnosis, Differential, Dysentery, Amebic, Feces, Female, Georgia, Helminthiasis, Hemorrhage, Humans, Infant, Japan, Male, Rectal Diseases, Respiratory Tract Infections, Turbellaria}, issn = {0022-3395}, author = {Walton, B C and Yokogawa, M} }