Abstract
Fluorescence in situ hybridization (FISH) is a cytogenetic technique where fluorescently labeled DNA probes are hybridized to their complementary sequences on chromosomes, allowing identification of the location of the selected DNA sequence. This protocol describes a method for producing spreads of meiotic chromosomes from male meiotic cells (meiocytes) of maize, as well as for conducting FISH on the chromosome spreads. The stand-alone chromosome spread method is useful for quick assessment of meiosis progression, for example, in meiosis-defective mutants. It can also be utilized in other ways, such as to determine an organism's chromosome number. When combined with FISH, chromosome spreads enable visualization of specific chromosome regions and are widely used to study chromosome organization and dynamics. Both methods can be easily adapted to also study mitotic chromosomes.