Cole E S, Cassidy-Hanley D, Hemish J, Tuan J, Bruns P J
Biology Department, St. Olaf College, Northfield, Minnesota 55057, USA.
Dev Biol. 1997 Sep 15;189(2):215-32. doi: 10.1006/dbio.1997.8648.
Conjugation in the freshwater ciliate Tetrahymena thermophila involves a developmental program that models meiosis, fertilization, and early developmental events characteristic of multicellular eukaryotes. We describe a gallery of five early-acting conjugation mutations. These mutants, cnj1-5, exhibit phenotypes in which specific steps in the conjugal pathway have been altered or eliminated. Specifically, cnj1 and cnj2 fail to condense their micronuclear chromatin prior to each of the three prezygotic nuclear divisions. This results in nuclear division failure, failure to replicate DNA, and failure to initiate postzygotic development. The cnj3 mutant appears to exhibit a defect in chromosome separation during anaphase of mitosis. cnj4 mutants successfully carry out meiosis I, yet are unable to execute the second meiotic division and abort all further development. cnj5 mutants are unable to initiate either meiosis I or meiosis II, yet proceed to execute all subsequent developmental events. These mutant phenotypes are used to draw inferences regarding developmental dependencies that exist within the conjugation program.
嗜热四膜虫这种淡水纤毛虫的接合过程涉及一个发育程序，该程序模拟了多细胞真核生物特有的减数分裂、受精和早期发育事件。我们描述了一组五个早期起作用的接合突变。这些突变体cnj1 - 5表现出接合途径中特定步骤被改变或消除的表型。具体而言，cnj1和cnj2在三个合子前核分裂的每一次之前都无法使它们的小核染色质浓缩。这导致核分裂失败、DNA复制失败以及合子后发育启动失败。cnj3突变体在有丝分裂后期的染色体分离过程中似乎表现出缺陷。cnj4突变体成功进行减数分裂I，但无法进行第二次减数分裂并终止所有进一步的发育。cnj5突变体既无法启动减数分裂I也无法启动减数分裂II，但会继续执行所有后续的发育事件。这些突变体表型被用于推断接合程序中存在的发育依赖性。
