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  • Vijay Kumar Singhal, Dalvir Kaur
    CYTOLOGIA
    2011年 76 巻 4 号 387-393
    発行日: 2011/12/25
    公開日: 2012/04/29
    ジャーナル オープンアクセス
    Cytological work on Vicia pallida Turcz. presents male meiotic studies in wild accessions gathered from the Kinnaur district of Himachal Pradesh. All 3 accessions uniformly shared the same meiotic chromosome number of n=12 in which 5 bivalents are relatively small sized as compared with the remaining 7 bivalents. This is the first report of tetraploid cytotype in the species against the earlier record of diploid cytotype (n=7) from the other region of Himalaya. Out of the 3 accessions scored presently, 1 accession showed a regular 12 bivalent formation, equal chromosome segregation during anaphases/telophases, normal tetrad formation and 99% pollen fertility with uniform sized pollen grains. The remaining 2 accessions depicted pollen mother cells (PMCs) with irregular meiotic behaviour which included the phenomenon of chromatin transfer among proximate meiocytes at different stages of meiosis, interbivalent connections and chromatin stickiness, out of plate bivalents at metaphase-I, lagging of chromosomes/laggards at anaphases, abnormal sporads (tetrads with micronuclei and polyads) and consequently some pollen sterility and pollen grains of variable sizes. The phenomenon of cytomixis which induces various meiotic abnormalities in the PMCs and consequently pollen sterility and pollen grains of heterogeneous sizes in V. pallida seems to be under direct genetic control.
  • Atsushi Tajima
    The Journal of Poultry Science
    2013年 50 巻 1 号 1-8
    発行日: 2013/01/25
    公開日: 2013/01/25
    [早期公開] 公開日: 2012/08/25
    ジャーナル フリー
    Conservation of avian genetic resources is important, as 13.0% (1,313/10,064) of known avian species are currently categorized as endangered by the International Union for Conservation of Nature and Natural Resources (IUCN, 2012). Development of an integrated system for conservation of avian genetics is necessary; however, germplasm conservation systems developed for mammals cannot be applied directly to avians, primarily due to the unique anatomical and physiological characteristics of the avian egg. Thus an alternative strategy for conservation of oviparous species of animals must be developed. Recent technological developments for producing germline chimeras by the transfer of primordial germ cells into recipient embryos has enabled the conservation and retrieval of chicken genetic resources in their complete form. Furthermore, the possibility of propagating endangered wild birds through interspecies germline chimeras has been proposed.  In the present review, the current status of avian genetic resource conservation is presented with a focus on the following 4 topics: 1) semen cryopreservation, 2) germline chimeras, 3) somatic nuclear transfer, and 4) other related technologies.
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