Meiosis: Sordaria Hybrid SporesLed by Corporal Ryan JahansoozAssisted by Privates Tyler Voss and Hunter Wolfbear DrobenaireBiology 001 Section 16 10-9-2013Abstract:This lab was an experiment involving close examination of the reproductive spores released by crushed cells that have grown over the past week in our petri dishes from last lab. This was accomplished by collecting a few cells and preparing them for viewing by crushing them on a microscopeslide. This released the spores within the cells so that they were easy to see using a simple light microscope. The end result was a clear picture of the random gene splicing process due to the different spore colors.Introduction:Meiosis is the process that reproductive cells go through to split a parent cell into four new cells, each with half of the chromosomes as the parent. It has two stages, meiosis 1 and meiosis 2. Both stagesare made of four stages: prophase, metaphase, anaphase, and telophase. All of these are crucial steps that must be taken every time a cell undergoes meiosis. The steps taken in meiosis are as follows:Prophase: The chromatin begins to condense and the nucleolus dissolves. Centrioles move to opposite ends of the cell. At this point, the chromosomes are visible under a microscope. The chromosomes also cross over each other to interchange genes. This allows for new and different outcomes.Metaphase: Chromosomes line up down the center of the cell with the aid of spindle fibers.Anaphase: Microtubules and spindle fibers separate the chromatids at the kinetochores and pull them to each end of the cell.Telophase: The chromosomes arrive at each end of the cell and the cell membranes begin to reform as the cell begins to split.The chromosomes disperse and are no longer visible..Once these stages have completed, the cell enters Meiosis 2. In this process, each stage occurs a second time. At last, there are 4 new cells, each with a new style of genetic information. The specific cell that was studied in this lab was that of Sordaria fimicola. This species of fungi specializes in feeding via external digestion by releasing enzymes into the environment in preparation to be absorbed into the cell through the cell walls. Sordaria fimicola are known as Ascomycota, or sac fungi,due to its reproductive cycle. It reproduces by producing sexual spores known as ascospores, which as contained in a flask- shaped structure called a perithecium. In the wild, this fungus is typically found on herbivore dung piles.Sordaria fimicola is a haploid cell for most of its lifecycle, but it will become diploid when the mycelia of two different strains fuse. Each strain combines to form a diploid nucleus known as a zygote. Once this happens, the cell immediately undergoes meiosis1 and 2, resulting in four haploid cells. Mitosis follows next, resulting eight haploid ascospores. This cycle repeats many times to form asci in theperithecium, and each ascospore can create a new fungus. This complex cycle is needed because a haploid cell cannot undergo meiosis, and a diploid cell cannot undergo mitosis.The experiments in this lab involve taking a few select cells from a sample of fresh sordaria and observing their ascospores inside of the perithecium to see how cells undergo meiosis in real life and how gene swapping affects the outcome.Material & Methods:The experimental procedures for this lab were adapted from a previously supplied protocol (Dulai, 2012). To ensure that the results were conclusive and solid, measures were taken to sanitize the lab area prior to experimentation. The cells were allowed to cultivate for one full week in a clean environment. The only minor discrepancies that occurred were due to the lack of experience and knowledge when supplying the fungi with the resources needed to cultivate. In the process, very minor contamination may have occurred due to prolonged exposure.Results:For starters, it appeared from the observations of the subaria cells using the light microscope that the most prominent ascus type in the samples was the light, wild type. This is most likely due to the dominance of the gene that makes the ascus light as opposed to the one that makes them dark. They asci were also in seemingly random orders inside the perithecium, but asci of types 4:4, 2:2:2:2, and 2:4:2 were by far the most numerous. The asci looked like this (FIG 1). The colors and variations were random due to the gene swapping that takes place in prophase.The total numbers asci variations that were counted out of fifty cells are recorded on this table, FIG 2.TOTAL Asci of type 4:4 (MI asci) TOTAL Asci of type 2:2:2:2 (M2 asci)TOTAL Asci of type 2:4:2(M2 asci)21 13 19TOTAL Asci of type 4:4 (MI asci) TOTAL Asci of type 2:2:2:2 (M2 asci)TOTAL Asci of type 2:4:2(M2 asci)44.25177 asci36144 asci19.7579 asciIt is clear that there is a dominance of alleles in these cells. We can see this from the ratios in Figs 1 and 2. There are far more asci that match the definitions of cell 1 than those in cells 2 and 3. This data was gathered using a light microscope and knowledge of how asci look inside of the perithecium.Discussion:The lab was a great success in that it was a great tool for displaying the results of gene swapping in real life. From observing the perithecium released from the cells during slide preparation, it was clear that not every perithecium contained the same ascospores. Some were white and some were black, withthe large majority being white. This is most likely due to white being the dominant allele. It is due to M1 and M2 that there was such a varied display of ascospores within the perithecium. Without M1 and M2, each generation of the fungus would be the same.While studying the cells under a light microscope, it became clear that the diploid number of chromosomes must always be even and never odd due to the way that meiosis works in that there are always two contributors. Therefore, there must always be an even number because each contributor willgive the same amount.It is important that genes cross during prophase because it allows for new strains of fungus to live and thrive or die. The constant mixing and exchanging of genetic material will ensure that the most effective results of reproduction survive to reproduce more than those cells that die off due to unfortunate combinations.References:1. Dulai, K. 2012. Cell Cycle and Mitosis and Meiosis Setup. Biology 001 Laboratory Exercises Manual. UC Merced.2. Jahansooz, R. 2013.