An ascospore is a
sporecontained in an ascusor that was produced inside an ascus. This kind of spore is specific to fungiclassified as ascomycetes ( Ascomycota).
Typically, a single ascus will contain eight ascospores. The eight spores are produced by a combination of a
meiosisdivision followed by a mitotic division. The meiosis division turns the original diploid zygotenucleus into four haploidones. That is, the single original cell from which the whole process begins contains two complete sets of chromosomes. In preparation for meiosis, all the DNAof both sets is duplicated, to make a total of four sets. The nucleus that contains the four sets divides in two stages, separating into four new nuclei - each of which has one complete set of chromosomes. Following this process, each of the four new nuclei duplicates its DNA and undergoes a division by mitosis.As a result, the ascus will contain four pairs of spores.
Saccharomycesproduces ascospores when grown on V-8 medium, acetate ascospor agar, or Gorodkowa medium. These ascospores are globose and located in asci. Each ascus contains 1-4 ascospores. The asci do not rupture at maturity. Ascospores are stained with Kinyoun stain and ascospore stain. When stained with Gram stain, ascospores are gram-negative while vegetative cells are gram-positive
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