A Study of Gene Mapping Using Tetrad Analysis in the Fungus Sordaira Fimicola
A Study of Gene Mapping
Using Tetrad Analysis in the Fungus Sordaira Fimicola
BISC 302 Genetics
Lab: Wednesday
June 14 2006
ABSTRACT
The fungus, Sordaria fimicola, selected for tetrad analysis due to its ease in observation of recombination events. These fungi have mutation in genes that control spore colour. Tetrad analysis can be conducted by crossing wild type spores with the two mutant types, tan and gray. Crossing wild type with the mutants can allow for direct observation of intact asci, showing effects of crossovers. Mapping distances between the gene and centromere can then be determined. INTRODUCTION
In most eukaryotes, recombination analysis cannot be used to map the loci of centromeres, because they show no heterozygosity that enable them to be used as markers (Griffiths, A., 2005). Also, it is difficult to observe all the results of a single meiosis. However, certain fungi can produce linear tetrads and centromeres can be mapped. Once such fungus Sordaria fimicola.
The spores from Sordaria fimicola divide mitotically to replicate their nuclei but do not complete cytokinesis. This gives rise to a giant multinucleate compartment called a mycelium. The mycelium extends long thread-like projections called hyphae (Fitzpatrick, K., 2006). At the point of fusion between two hyphae, each hypha contributes a haploid nucleus to generate a binucleate cell. This binucleate cell becomes a perithecium. As more fused nuclei (fusion of two hypha) divide mitotically, more binucleate cells are produced. Each
binucleate cell will undergo meiosis when its two nuclei fuse and each cell will give rise to an ascus (Fitzpatrick, K., 2006). The meiotic divisions take place along the long axis of the ascus so that each meiocyte produces a linear array of eight ascospores, an octad (Griffiths, A., 2005). It is convenient the species of Sordoria is homothallic; although it is impossible to prevent self fertilization, however, they have
Using Tetrad Analysis in the Fungus Sordaira Fimicola
BISC 302 Genetics
Lab: Wednesday
June 14 2006
ABSTRACT
The fungus, Sordaria fimicola, selected for tetrad analysis due to its ease in observation of recombination events. These fungi have mutation in genes that control spore colour. Tetrad analysis can be conducted by crossing wild type spores with the two mutant types, tan and gray. Crossing wild type with the mutants can allow for direct observation of intact asci, showing effects of crossovers. Mapping distances between the gene and centromere can then be determined. INTRODUCTION
In most eukaryotes, recombination analysis cannot be used to map the loci of centromeres, because they show no heterozygosity that enable them to be used as markers (Griffiths, A., 2005). Also, it is difficult to observe all the results of a single meiosis. However, certain fungi can produce linear tetrads and centromeres can be mapped. Once such fungus Sordaria fimicola.
The spores from Sordaria fimicola divide mitotically to replicate their nuclei but do not complete cytokinesis. This gives rise to a giant multinucleate compartment called a mycelium. The mycelium extends long thread-like projections called hyphae (Fitzpatrick, K., 2006). At the point of fusion between two hyphae, each hypha contributes a haploid nucleus to generate a binucleate cell. This binucleate cell becomes a perithecium. As more fused nuclei (fusion of two hypha) divide mitotically, more binucleate cells are produced. Each
binucleate cell will undergo meiosis when its two nuclei fuse and each cell will give rise to an ascus (Fitzpatrick, K., 2006). The meiotic divisions take place along the long axis of the ascus so that each meiocyte produces a linear array of eight ascospores, an octad (Griffiths, A., 2005). It is convenient the species of Sordoria is homothallic; although it is impossible to prevent self fertilization, however, they have
References: Fitzpatrick, K., 2006 Bisc302 Lecture 8; http://webct.sfu.ca/webct/cobaltMainFrame.dowebct, June 7, 2006. Fitzpatrick, K., 2006 Bisc302 Lecture 9; http://webct.sfu.ca/webct/cobaltMainFrame.dowebct, June 7, 2006. Fitzpatrick, K., 2006 Tetrad analysis lab handout; http://webct.sfu.ca/webct/cobaltMainFrame.dowebct, June 7, 2006. Gelbart, W.M., Griffiths, A., Lewontin, R., Miller, J., Suzuki, D., Wessler, S. (2005) Introduction to Genetic Analysis (pp.129-131). New York: W.H. Freeman and Company