Biology Forums - Study Force

In somatic cell hybridization between different species, usually most of the chromosomes from one species are lost. We can force preferential retention of certain chromosome by giving selection pressure, chromosome which otherwise would have been lost.
It is also observed that sometime only fraction of certain chromosome survive (the lost part is assumed to be redundant).
My question is what is the mechanism of chromosome loss? I can think about failure of synchronization of certain chromosome ... and they are eventually lost. what about fragment of chromosome ? Is there active mechanism that push out the chromosome from the cell, or actively degrade certain chromosome?

Interesting question, the fusion of somatic cells usually results in polyploidy, but like you mentioned, there is chromosome loss. The reason for this is primarily due to differences in generation time, for instance, a monkey will have a longer generation time than a mouse. Interestingly, in the case of the human-Chinese hamster hybrid, human chromosomes are lost. If a mutant hamster cell with a nutritional deficiency (e.g., one that cannot grow in the absence of glycine) is hybridized with a human cell without the deficiency, the hybrid cell will not show the deficiency (in this instance the hybrid will be able to grow in a medium without glycine). The hybrid cells will then produce clones showing extensive loss of the human chromosomes. The one human chromosome the hybrid cannot lose is the one that carries the human gene that compensates for the hamster cell mutation, for without that gene the cell would die. The exact mechanism why chromosome loss occurs by somatic cell hybrids is not understood, really.

Your answer lies in this paper, thanks Duddy.

X chromosome-induced reversion of chromosome segregation in mouse/Chinese hamster somatic cell hybrids : Cellular recognition of native and foreign X chromosomes