Tetrad Dissection in Fission Yeast

Abstract

Tetrad dissection is a powerful tool in yeast genetics that allows the analysis of products of a single meiosis. With just a few tetrads, it is possible to determine linkage, identify unique phenotypes associated with double mutants, or assess specific meiotic defects. Strains are crossed on nitrogen-limiting medium for 3 days. With the help of a micromanipulator, ripe asci are isolated to spots 5 mm apart on a YES plate. Incubation at 36 °C for about 3–5 h is necessary for the ascus walls to break down. Once the spores are released, they are individually placed in a row containing four tetrad products, separated by 5 mm. The spores are then put in the appropriate temperature for the cross until colonies form, and phenotypes are assessed by replica plating or microscopic analysis.