Tetrad dissection microscope system for genetic analysis

“酵母遗传学的惊人力量”是科学家们经常使用的一个短语，他们将酵母分裂菌（Schizosaccharomyces pombe）或酿酒酵母（Saccharomyces cerevisiae）作为实验模型。这些相对简单的单细胞生物长期以来一直被用于实验，目的是更好地理解细胞生理学和遗传学的许多方面，这些实验在人类等高等生物中很难或不可能进行。通过这种方式，对这些酵母的研究使我们对细胞如何控制其生长和分裂的认识取得了巨大的进步，从而为理解癌症的遗传学提供了一个理论框架。研究pombe或酿酒酵母的主要优点之一是易于进行遗传分析。这种基因分析的关键是一种被称为四分体解剖显微镜的工具。该仪器由普通光学显微镜和互补的微操作工具（操纵杆，专用台，微针）组成，用于物理分离来自两个单个酵母菌株交配的四个个体“子囊孢子”。通过将两个携带不同基因突变的菌株进行交配，然后分析分离出来的子囊孢子，可以分离出携带两种突变的菌株，从而分析它们之间的遗传相互作用。使用同样的逻辑，可以创建包含复杂突变组合的菌株，用于研究正在研究的生物问题的遗传控制。在这个特殊的例子中，我们有兴趣使用四分体解剖显微镜来更好地理解“细胞分裂”的遗传调控，细胞分裂是细胞周期的最后一步，在这个过程中，单个母细胞分裂成两个独立的子细胞。

The "awesome power of yeast genetics" is a phrase commonly used by scientists employing the yeasts Schizosaccharomyces pombe or Saccharomyces cerevisiae as experimental models.  These relatively simple unicellular organisms have long been used in experiments - aimed at better understanding many aspects of cellular physiology and genetics - that would have been difficult or impossible to perform in higher organisms such as humans.  In this way, research in these yeasts have led to tremendous advancements in our knowledge of how cells control their growth and division, and thus have provided a theoretical framework for understanding the genetics of cancer.  One of the main advantages of studying S. pombe or S. cerevisiae is the ease of genetic analysis.  Key to this genetic analysis is a tool referred to as a tetrad dissection microscope.  This instrument, consisting of a normal light microscope together with complementing micro-manipulation tools (joystick, specialized stage, micro-needle), is used to physically separate the four individual "ascospores" derived from the mating of two individual yeast strains.  By mating two strains carrying mutations in different genes, and then analyzing the separated ascospores, it is possible to isolate a strain carrying both mutations and thus to analyze the genetic interactions between them.  Using this same logic it is possible to create strains containing complex combinations of mutations that can be used to study the genetic control of the biological problem under study.  In this particular instance we are interested in using a tetrad dissection microscope to better understand the genetic regulation of "cytokinesis", the last step of the cell cycle in which an individual mother cell cleaves itself into two independent daughters.