• 我要登录|
  • 免费注册
    |
  • 我的丁香通
    • 企业机构:
    • 成为企业机构
    • 个人用户:
    • 个人中心
  • 移动端
    移动端
丁香通 logo丁香实验_LOGO
搜实验

    大家都在搜

      大家都在搜

        0 人通过求购买到了急需的产品
        免费发布求购
        发布求购
        点赞
        收藏
        wx-share
        分享

        Feulgen-DNA Cytophotometry for Estimating C Values

        互联网

        757
        The genome size of an organism, commonly known as its C value, is defined as the content of DNA (measured by weight or numbers of basepairs) in a single copy of the sequence of DNA found within the cells of an organism (i.e., the amount of DNA in a haploid chromosome set, where 1n=1C) (1 ). A single sperm of Drosophila melanogaster contains 0.18 pg DNA, which is the C value for this species (2 4 ). By convention, the DNA content of a diploid somatic cell of this species can then be expressed as 2n=8=2C=0.36 pg DNA for the male diploid genotype of AAXY (3 ). And, 2C=0.40 pg DNA for a diploid Drosophila female somatic cell with the genotype of AAXX because the X chromosome contains a bit more DNA than the Y chromosome in this species (see Table 1 ). These considerations follow from the “DNA Constancy Hypothesis” formulated in the 1950s (5 8 ) that the DNA content of nuclei of a eukaryotic species is essentially constant among the individuals within a given species and constitutes the repository of genetic information for that taxon. For example, genome sizes, expressed as C values, are listed in Table 1 for 10 different species of Drosophila .
        Table 1  Estimates of Genome Size for 10 Different Species of Drosophila Expressed as C Values in pg DNA per Nucleus a and Number of Nucleotide Basepairs (np)

        Species

        C Value = DNApg per nucleus

        np�108

        D. americana

        0.30

        2.74

        D. arizonensis

        0.22

        2.01

        D. eohydei

        0.24

        2.19

        D. funebris

        0.23

        2.10

        D. hyd ei

        0.20

        1.83

        D. melanogaster (♂)

        0.18

        1.64

        D. melanogaste (♀)

        0.20

        1.82

        D. miranda

        0.30

        2.74

        D. neohydei

        0.19

        1.73

        D. simulans

        0.12

        1.10

        D. virilis

        0.34

        2.89

        Chicken b

        1.25

        11.41

        Xenopus laevis b

        3.15

        28.76

        a Computed by assuming 9.13�108 nucleotide pairs per picogram of DNA (9 ).
        b C values are shown for red blood cell (RBC) nuclei of two reference standards. Source : Adapted from T. R. Gregory, www.genomesize.com/insects. For primary citations,see database at this website.
        ad image
        提问
        扫一扫
        丁香实验小程序二维码
        实验小助手
        丁香实验公众号二维码
        扫码领资料
        反馈
        TOP
        打开小程序