Some of the fungi are a good source of food, like some mushrooms. At the same time out of these mushrooms are very poisonous and an individual who eats these mushrooms s/he may end up to death if untreated appropriately. At universal level, as fungi are found almost in all types of environment and so they are an imortant component of the ecosystem where they take part in the decomposition of the deaying material. Initally, fungi were placed in the plant kingdom because of their resemblance. Later on, it was found that they are closer to animals instead of plants. But they have been separately grouped in their own kingdom (Fungi, 2006).
The Ascomycota also known as sac fungi or ascomycetes because of their morphological resemblance. Mmbers of this division form meiotic spores called ascospores, which are enclosed in a special sac-like structure called an ascus. Sseveral ascomyctes have been used for elucidating principles of genetics and heredity, one member of the group is Neurospora crassa.
In 1927, Shear and Dodge gave a very comprehensive account of fungus Neurospora. They called it with this name because of its resemblance to nerves; the striations which develop on the wall of ascospore are like nerves. They discovered the mating types A and a of this genus Neurospora and further described the life histories of three species, two eight-spored heterothallic species named N. crassa and N. sitohila and one four-spored homothallic species N. tetrasperma. (Perkins, 2002)
Their explanation of the characteristics related to thallism was based on their work on nucleus of these species. In fact, there is programming of ascus development in N. tetrasperma in a way that each of the four ascospores encloses two nuclei of the opposite mating type. So there is self-fertilization of single-ascospores (Raju, 2003).
While in eight-spored N. crassa, the situation is a bit different and which is expected, as it is eight-spored as compared to the four-spored species. In N. crassa, the ascospore pairs are aligned themselves in linear fashion and exhibit genetic events during the process of meiosis. The process of crossover, which occurs at the four-strand stage during the meiotic division, becomes visually obvious. In N. crassa, the segregation of alleles during meiotic division is not fixed but it varies depending upon the relation between the gene marker and the centromer