Sordoria Lab
Determining the Crossover Frequency in Sordaria fimicola
Introduction
Meiosis is an important part of the life cycle that gives rise to the genetic variation in offsprings. Meiosis in fungi differs from those in plants and animals. Fungi are composed of hyphae, which are tubules that make up the frame. These hyphae together form a clump or a mat that is the mycelium (Campbell, 637). The hyphae are key to fungus reproduction. Typically fungi produce large amounts of spores through either sexual or asexual reproduction. Fungal hyphae are normally haploid. When two fungi mate, the hyphae fuse together. The movement of the two fungal nuclei into one cytoplasm is known as dikaryon. Next, the cells go into karyogamy. The two nuclei fuse and provide diploid cells. These newly produced cells then go through mitosis and meiosis that cultivate spores (Campbell, 639). The spores are called ascopores and are found in a saclike structure that is the ascus. The spores germinate and form hyphae (Campbell, 64)
Species of the genus Sordaria share a number of characteristics that are advantageous for genetic studies. They all have a short life cycle, usually 7-12 days, and are easy to grow on nutrient agar in dish cultures. All kinds of mutants are easily induced and readily obtainable with particular ascospore color mutants. These visual mutants aid in tetrad analysis, especially in analysis of intragenic recombination. ( Campbell 72) A common lab use is to observe meiosis and mitosis in the fruiting bodies, called perithecia. An interesting feature of S. fimicola is that its fruiting body is phototrophic. Thus, as it grows the stalk will bend toward a light source and when the sac bursts, the spores are shot towards the light.
There are four “Evolution Canyons”, each of which consists of two mountain slopes with varying climates. Evolution canyon is a research model site, which is used for understanding microevolution and can be used to study how mutation and
Introduction
Meiosis is an important part of the life cycle that gives rise to the genetic variation in offsprings. Meiosis in fungi differs from those in plants and animals. Fungi are composed of hyphae, which are tubules that make up the frame. These hyphae together form a clump or a mat that is the mycelium (Campbell, 637). The hyphae are key to fungus reproduction. Typically fungi produce large amounts of spores through either sexual or asexual reproduction. Fungal hyphae are normally haploid. When two fungi mate, the hyphae fuse together. The movement of the two fungal nuclei into one cytoplasm is known as dikaryon. Next, the cells go into karyogamy. The two nuclei fuse and provide diploid cells. These newly produced cells then go through mitosis and meiosis that cultivate spores (Campbell, 639). The spores are called ascopores and are found in a saclike structure that is the ascus. The spores germinate and form hyphae (Campbell, 64)
Species of the genus Sordaria share a number of characteristics that are advantageous for genetic studies. They all have a short life cycle, usually 7-12 days, and are easy to grow on nutrient agar in dish cultures. All kinds of mutants are easily induced and readily obtainable with particular ascospore color mutants. These visual mutants aid in tetrad analysis, especially in analysis of intragenic recombination. ( Campbell 72) A common lab use is to observe meiosis and mitosis in the fruiting bodies, called perithecia. An interesting feature of S. fimicola is that its fruiting body is phototrophic. Thus, as it grows the stalk will bend toward a light source and when the sac bursts, the spores are shot towards the light.
There are four “Evolution Canyons”, each of which consists of two mountain slopes with varying climates. Evolution canyon is a research model site, which is used for understanding microevolution and can be used to study how mutation and
References: 1.) Campbell, Neil A., Jane B. Reece, et al. Biology. Eighth ed. San Francisc: Pearson Benjamin Cummings, 2008. Print. 2.) Sordaria Genetics and Meiosis. LAB MANUAL 3.) Singaravelan N, Pavlicek T, Beharav A, Wakamatsu K, Ito S, et al. (2010) Spiny Mice Modulate Eumelanin to Pheomelanin Ratio to Achieve Cryptic Coloration in “Evolution Canyon,” Israel. PLoS ONE 5(1): e8708. doi:10.1371/journal.pone.0008708