2003 Volume 44 Issue 1 Pages 2-9
Teaching materials to show visually meiotic pairing, separation and recombination of chromosomes in a bigeneric hybrid Gasteria lutzii x Aloe aristata were developed by genomic in situ hybridization (GISH) using the DNA of the original species as a probe. Genomic in situ hybridization is a molecular technique which now allows chromosomes from different parents to be “painted” different colors.
Chromosome painting by GISH enabled the direct and clear study of homoeologous chromosome behavior during the meiotic process. That is, it become possible through color-coding to present visually the following: reduction of chromosome numbers by the bivalent formation and random assortment of paired chromosomes and segregation to both poles at first meiotic division, followed by a separation of chromatids of each chromosome to the opposite poles and transmission of them to the gametes at second meiotic division.
Using the pictures provided by GISH, students could understand the mechanism of separation and recombination of chromosomes as different genomes. Then, students could acknowledge that intergenomic recombinations were incorporated into the gametes.