Foe V E, Alberts B M
J Cell Biol. 1985 May;100(5):1623-36. doi: 10.1083/jcb.100.5.1623.
We have studied the morphology of nuclei in Drosophila embryos during the syncytial blastoderm stages. Nuclei in living embryos were viewed with differential interference-contrast optics; in addition, both isolated nuclei and fixed preparations of whole embryos were examined after staining with a DNA-specific fluorescent dye. We find that: (a) The nuclear volumes increase dramatically during interphase and then decrease during prophase of each nuclear cycle, with the magnitude of the nuclear volume increase being greatest for those cycles with the shortest interphase. (b) Oxygen deprivation of embryos produces a rapid developmental arrest that is reversible upon reaeration. During this arrest, interphase chromosomes condense against the nuclear envelope and the nuclear volumes increase dramatically. In these nuclei, individual chromosomes are clearly visible, and each condensed chromosome can be seen to adhere along its entire length to the inner surface of the swollen nuclear envelope, leaving the lumen of the nucleus devoid of DNA. (c) In each interphase nucleus the chromosomes are oriented in the "telophase configuration," with all centromeres and all telomeres at opposite poles of the nucleus; all nuclei at the embryo periphery (with the exception of the pole cell nuclei) are oriented with their centromeric poles pointing to the embryo exterior.
我们研究了果蝇胚胎在合胞体胚盘阶段细胞核的形态。利用微分干涉相差光学显微镜观察活胚胎中的细胞核；此外，在用DNA特异性荧光染料染色后，对分离的细胞核和整个胚胎的固定标本进行了检查。我们发现：（a）在每个核周期的间期，核体积急剧增加，然后在前期减小，间期最短的那些周期中核体积增加的幅度最大。（b）胚胎缺氧会导致快速的发育停滞，再通气后可逆转。在这种停滞期间，间期染色体靠在核膜上凝聚，核体积急剧增加。在这些细胞核中，单个染色体清晰可见，每条凝聚的染色体可以看到沿着其全长附着在肿胀核膜的内表面，使核腔中没有DNA。（c）在每个间期细胞核中，染色体呈“末期构型”排列，所有着丝粒和所有端粒位于细胞核的相对两极；胚胎周边的所有细胞核（极细胞的细胞核除外）其着丝粒极指向胚胎外部。
