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Volume 43 (2010)
- Issue 2 Pages 89-
- Issue 1 Pages 5-
Volume 43, Issue 2
Displaying 1-3 of 3 articles from this issue
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Yoshiomi Takagi2010 Volume 43 Issue 2 Pages 89-93
Published: 2010
Released on J-STAGE: August 01, 2016
JOURNAL FREE ACCESSAlternation of haploid and diploid is a common feature of the sexual reproduction. Before establishment of such sexual haploidization through meiosis and sexual diploidization through fertilization, I hypothesize the asexual cycle alternating asexual haploidization and asexual diploidization, which deserves to be called primitive sexual reproduction.View full abstractDownload PDF (624K)
Short Communication
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Akira Yanagi2010 Volume 43 Issue 2 Pages 95-100
Published: 2010
Released on J-STAGE: August 01, 2016
JOURNAL FREE ACCESSTo elucidate the timing of commitment to autogamy in Paramecium bursaria, cells were treated with an autogamy-inducing agent (1.25% methyl cellulose) for 0, 1, 2, 3, 5, and 24 h, and the duration of treatment required for the induction of autogamy was examined 24-25.5 h after the onset of treatment. Many cells treated for 0-2 h were at the vegetative stage, but many cells treated for 3-24 h were at stages from the third pre-zygotic division to the third post-zygotic division and normally underwent autogamy. Therefore, treatment with methyl cellulose for 3 h or more is considered necessary for the induction of autogamy. However, some of the cells treated for 3 h were at the stage of developing either a swollen and spindle-shaped micronucleus or an early round-shaped micronucleus, which is indicative of the pre-meiotic S phase. This suggests that if cells proceed beyond the stage of an early round-shaped micronucleus, they normally undergo autogamy, but if not, they terminate at the stage of either a swollen and spindle-shaped micronucleus or an early round-shaped micronucleus. Consequently, cells of P. bursaria are committed to autogamy just after the stage of an early round-shaped micronucleus (the pre-meiotic S phase).View full abstractDownload PDF (221K) -
Satoshi Ohta, Akira Yanagi2010 Volume 43 Issue 2 Pages 101-105
Published: 2010
Released on J-STAGE: August 01, 2016
JOURNAL FREE ACCESSTo analyze cell-cell adhesion in Paramecium caudatum, we examined methyl cellulose-induced autogamous cells for their ability to adhere. It was found that the autogamous cells have cell-cell adhesion ability. In addition, we examined the proportion of adhering (conjugating) pairs derived from autogamous cells at various stages (0.5, 1, 2, 4, 6, 9 and 12 h after the onset of induction of autogamy). The proportion of adhering cells reached a maximum about 2 h after the onset of induction of autogamy, and thereafter, rapidly decreased by 4 h after the onset, eventually reaching almost zero 6 h after the onset. These results suggest that there is a transient expression or activation of molecule(s) involved in cell-cell adhesion around 2 h after the onset of induction of autogamy.View full abstractDownload PDF (284K)
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