Sexual reproduction depends on the generation of haploid gametes from diploid progenitor cells in a process called meiosis. Although we understand certain aspects of meiosis, some of the key regulators of meiotic chromosome segregation are still missing and only now we do have tools to systematically identify these proteins and to determine their function.In this project, we want to screen the recently released S. pombe knock-out collection to identify mutants missegregating chromosomes during meisosis. Our priority will be to characterize mutants defective in mono-orientation of sister kinetochores during the first meiotic division, as this is the least understood aspect of meiotic chromosome segregation. The fission yeast S. pombe is an excellent model organism for such studies due to the fact that S. pombe kinetochores, like those of most eukaryotic cells, are associated with multiple microtubules. Moreover, it is amenable to both genetic and cell biology techniques and highly synchronous meiosis can be induced. In order to understand the function of identified proteins, we will combine genetic, biochemial and cell biology techniques.We believe that it is important to understand mechanisms governing meiotic chromosome segregation. Meiosis is not only a fundamental and fascinating process, it is also vital to fertility and human health. Defects in chromosome segregation during meiosis are the major cause of miscarriages, birth defects, infertility and genetic disorders such as Down Syndrome. The potential benefits of thorough understanding of chromosome segregation during meiosis are impressive. They could reveal much about the mechanism of gamete development and sexual reproduction with implications for diagnostics and treatment of infertility, certain cancers and genetic diseases.