Chromosome Science
Online ISSN : 2185-0852
Print ISSN : 1344-1051
ISSN-L : 1344-1051
Volume 24, Issue 3-4
Displaying 1-6 of 6 articles from this issue
Regular Article
  • Neha Katnoria, Gurinder Kaur Walia
    2021 Volume 24 Issue 3-4 Pages 55-61
    Published: 2021
    Released on J-STAGE: July 06, 2022
    JOURNAL FREE ACCESS

    Cytological studies of seven species of family Euphaeidae were carried out. Among them three Dysphaea and two Euphaea species were investigated for the first time. All the species investigated possessed n=13 complement which is typical number of the family. C-bands were mostly appeared on terminal regions of all the autosomal bivalents in the seven species. The smallest chromosome (m) bivalents in Bayadera indica and Dysphaea ethela were C-negative, while less amount of Cheterochromatin in D. walli. C-bands were observed on both terminals of m bivalents in D. gloriosa and Euphaea fraseri. In the X chromosomes, terminal C-band on one side appeared in Anisopleura lestoides, B. indica and D. walli and dark C-bands on both terminals in E. fraseri and E. ochracea. Entire C-positive X chromosomes was observed in D. ethela and D. gloriosa. Nucleolar organizer regions (NORs) were observed at chiasmatic ends of either one or both terminals of autosomal bivalents. X chromosome possessed dark NOR on one terminal in A. lestoides, D. gloriosa, D. walli and E. ochracea and entirely NOR rich in B. indica, D. ethela and E. fraseri. The m bivalent possessed NOR on one terminal in D. ethela and D. gloriosa, while it was NOR-negative in B. indica, D. walli, and E. fraseri. In sequence specific staining, variable signals were seen but most of the species showed DAPI bright and CMA3 light regions at terminal ends.

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  • Yoshikane Iwatsubo
    2021 Volume 24 Issue 3-4 Pages 63-65
    Published: 2021
    Released on J-STAGE: July 06, 2022
    JOURNAL FREE ACCESS

    Rumex acetosa is a dioecious plant which has sex chromosomes of XX in females (2n=14=12A+XX) and XY1Y2 in males (2n=15=12A+XY1Y2). While most plants of this species are diploid, roughly 1% of wild R. acetosa distributed in Japan are triploid with 2n=21=18A+XXX or 2n=22=18A+XXY1Y2. Tetraploid plants with 2n=28=24A+XXXX or 2n=29=24A+XXXY1Y2 and hyperdiploid plants exist in the natural population. A diploid R. acetosa lacking one autosomal chromosome (hypodiploid plant) was also reported by Kuroki and Kurita (1975).

    Recently, the author identified a diploid plant missing the Y2 chromosome (2n=14=12A+XY1) in a roadside grassland. This plant bloomed male flowers, and its progeny after crossing with a normal female plant had a chromosome complement of 2n=14=12A+XX, suggesting that pollen grains with a chromosome set of 6A+X can fertilize, whereas those with a 6A+Y1 chromosome set do not mature until fertilization or are incapable of fertilizing.

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  • Kohei Nagao, Souichirou Kubota, Yuji Goto
    2021 Volume 24 Issue 3-4 Pages 67-70
    Published: 2021
    Released on J-STAGE: July 06, 2022
    JOURNAL FREE ACCESS

    In a Japanese hagfish, Eptatretus burgeri, 16 chromosomes (E-chromosomes), corresponding to 20.9% of the total germline genome DNA, are expelled from presumptive somatic cells (2n=52). To date, at least 11 eliminated repetitive DNA families amplified selectively in the germline genome have been identified from this species, and FISH analysis showed that almost all repetitive families such as EEEb1 (Eliminated Element of E. burgeri 1) were selectively detected on all E-chromosomes. On the other hand, EEEo1 (Eliminated Element of E. okinoseanus 1) and EEEo2 were not detected in E-chromosomes. The present study demonstrated that the signals as the pinpoint were detected on the interstitial region of the identical bivalent EEEb1-negative chromosome (non-Echromosome) in the spermatocytes, and neither EEEo1 nor EEEo2 signals were observed in somatic cells. Thus, this is the first report showing the internal deletion of eliminated repetitive DNA families from non-E-chromosomes in this species.

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Abstracts of the 72nd Annual Meeting of the Society of Chromosome Research
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