Search

When the centromere is in the middle of the chromosome (a metacentric chromosome), there are two long arms and when the centromere is located at the top of the chromosome, one arm is shorter (an acrocentric chromosome) or barely there (a telocentric chromosome). Robertsonian translocations occur when the long arms of two non-homologous telocentric or acrocentric chromosomes fuse at the centromere to form a new metacentric chromosome and the short arms are lost. In simple heterozygotes metacentric chromosomes pair with each homologous telocentric chromosome, forming a chain of three chromosomes. Chromosomal asynapsis directly disrupts the normal silencing of the sex chromosomes and it may be the expression of the sex chromosomes during male meiosis that causes hybrid sterility (Bhattacharyya et al. 2013; Bhattacharyya et al. 2014). [Extracted from the article]