The purpose of this study on the fungus sordaria fimicola is to examine crossing over during meiosis. Crossing over should occur and hybrid sordaria should form, though in a smaller ratio then non-crossing over asci. The two allelic forms of sordaria that were crossed were the black type allele and the tan type allele. Two squares of each allele were removed from their separate myecelial mat of hyphae and placed in a crossing over Petri dish. This was done using aseptic technique in order to avoid killing the fungus. Aseptic technique involved submerging the metal spatula, which was used to transfer the fungus onto the Petri dish, into ninety-five percent ethanol, and then placed over a flame and allowed to cool for ten to fifteen seconds. After each fungus is placed into its corresponding quadrant, it is left to incubate in the dark at twenty-two to twenty-four degrees Celsius for seven days. After one week, the sordaria has grown and hybrids have formed. Spores are removed from the Petri dish and examined under the microscope to see if hybrids have formed and if so, then which formation is visible. According to this particular experiment, out of a total of twenty-four MI and MII asci, eight were MI and sixteen were MII. Five of the sixteen were in the formation of two plus two plus two plus two, and the other eleven were in the formation of two plus four plus two. Thus the percentage of asci showing crossover is sixty-seven percent and the frequency is thirty-three and a half percent.
Sordaria Fimicola is a fungus whose main usage is to study processes such as gene segregation and crossing over during meiosis. Sordaria spends most of its life cycle in the haploid state. Ascospores are spores produced in a sac called the ascus. Ascospores of sordaria are usually black, though, as in most genes various allelic forms exist. Mutations in these specific genes can cause either tan or gray mutant alleles. The combination of these mutant...