Rosalind Silverman-Gavrila (2011) CIL:8074, Drosophila melanogaster. CIL. Dataset

Early embryonic divisions in Drosophila are syncytial. Nuclei undergo mitosis synchronously for the first 14 nuclear cycles, in which 6000 nuclei will form, followed by cellularization (Foe and Alberts, 1983). At nuclear cycle 10, nuclei are at the embryo cortex and can be easily visualized. This movie, an ASCB 2005 Celldance contest winner, shows a Drosophila embryo from a line expressing a fusion protein of GFP and histone (Clarkson and Saint, 1999). This fusion protein enables the visualization of DNA and the behavior of chromosomes during two consecutive divisions. Interphase nuclei contain DNA that is not assembled in chromosomes. Chromosome condensation takes place during prophase. In prometaphase, chromosomes attach to division spindles and congress at the cell equator. Once all chromosomes are at the metaphase plate, they segregate and move towards opposite poles in anaphase. In telophase, chromosomes decondense and nuclei reform. If the division went well the cycles start again. However, if anything goes wrong, the chromosomes do not condense and the nuclei sink in the middle of the embryo, a process called nuclear fallout. This is the case with the two nuclei in the middle of the image: each will sink in one of the 2 cycles.

Embryos were collected 2 hours after they were laid, dechorionated with 50% bleach and visualized by confocal microscopy. Images were captured with a Nikon Eclipse TE2000-E inverted microscope (Nikon Mississauga, ON, Canada) using a Plan Apochromat 40 x 1.5/NA1.0 oil immersion lens. The visualization setting included a Perkin Elmer Life Sciences UltraVIEW confocal spinning disk (Perkin Elmer Life Sciences, Missisauga, ON, Canada) and a Hamamatsu Orca-ER camera (Hamamatsu Photonics, Hamamatsu, Japan). Images were acquired at room temperature, every 8 seconds at 3-5 Z series of 40 m steps using the MetaMorph software (Universal Imaging, West Chester, PA).

Clarkson M, Saint R. A His2AvDGFP fusion gene complements a lethal His2AvD mutant allele and provides an in vivo marker for drosophila chromosome behavior. DNA Cell Biol. 1999;18:457-62.

Foe VE, Alberts BM. Studies of nuclear and cytoplasmic behaviour during the five mitotic cycles that precede gastrulation in Drosophila embryogenesis. J Cell Sci 1983;61:31-70.

Original resource provided by Rosalind V Silverman-Gavrila. Work conducted at University of Toronto, Toronto, CA. Original video created in December 2003. Video: Quicktime. Digitization process: Recompressed with H.264 codec, automatic keyframes selected, and data rate reduced (restricted to 768 kbs optimized for streaming) in Quicktime Pro. New file size: 3.78 Mb; FPS: 5; Data rate: 792.14 kbs; Codec: H.264.

Original resource: received from authors as avi file; File size: 4.98 Mb; Duration: 00:00:40.00; Dimensions: 323 x 308 pixels; FPS: 5; Data rate: 1.05 Mbs; Codec: Apple Cinepak.

在果蝇的早期胚胎分裂过程中，细胞质核同步进行，直至前14个细胞周期结束，期间将形成6000个细胞核，随后进入细胞化阶段（Foe 和 Alberts，1983年）。在第10个细胞周期时，细胞核位于胚胎皮质，易于观察。本视频为2005年ASCB Celldance竞赛的获奖作品，展示了由表达GFP和组蛋白融合蛋白的果蝇胚胎（Clarkson 和 Saint，1999年）。此融合蛋白使得DNA和染色体在连续两次分裂过程中的行为得以可视化。间期细胞核含有未组装成染色体的DNA。染色体凝缩发生在前期。在前期，染色体附着于分裂纺锤体并在细胞赤道会聚。一旦所有染色体位于中期板上，它们将在后期分离并向相反的两极移动。在末期，染色体解凝并重新形成细胞核。如果分裂过程顺利进行，周期将重新开始。然而，如果出现任何问题，染色体将不会凝缩，细胞核将在胚胎中部下沉，这一过程被称为核沉降。图像中间的两个细胞核即为这种情况：每个细胞核将在其中一个周期中下沉。胚胎在孵化后2小时内收集，用50%的漂白剂脱去卵黄囊，并通过共聚焦显微镜进行可视化。图像使用尼康Eclipse TE2000-E倒置显微镜（尼康密西沙加，加拿大）捕获，配备Plan Apochromat 40 x 1.5/NA1.0油浸镜头。可视化设置包括Perkin Elmer Life Sciences UltraVIEW共聚焦旋转盘（Perkin Elmer Life Sciences，密西沙加，加拿大）和Hamamatsu Orca-ER相机（Hamamatsu Photonics，日本）。图像在室温下，每8秒捕获3-5个Z系列、40微米步长的图像，使用MetaMorph软件（Universal Imaging，宾夕法尼亚州韦斯特切斯特）进行采集。Clarkson M，Saint R. A His2AvDGFP融合基因互补致死性His2AvD突变等位基因，并为果蝇染色体行为提供体内标记。DNA细胞生物学。1999；18:457-62。Foe VE，Alberts BM. 研究果蝇胚胎发生过程中，在原肠形成之前的前五个有丝分裂周期的细胞核和细胞质行为。细胞科学杂志。1983；61:31-70。原始资源由Rosalind V Silverman-Gavrila提供。在多伦多大学，多伦多，加拿大进行研究。原始视频创建于2003年12月。视频格式：Quicktime。数字化过程：使用Quicktime Pro以H.264编解码器重新压缩，自动选择关键帧，并将数据速率降低至768 kbs以优化流媒体（优化后的新文件大小：3.78 Mb；帧率：5；数据速率：792.14 kbs；编解码器：H.264）。原始资源：以avi文件形式从作者处接收；文件大小：4.98 Mb；持续时间：00:00:40.00；尺寸：323 x 308像素；帧率：5；数据速率：1.05 Mbs；编解码器：Apple Cinepak。