Age-associated alterations in the micromechanical properties of chromosomes in the mammalian egg

A Northwestern University Physical Sciences-Oncology Center outreach pilot project lead to a novel physical approach that shows aging-related changes in the micromechanical properties of meiotic metaphase II chromosomes in mouse oocytes are associated with deleterious in chromosome duplication and egg quality.  In collaboration with UC Berkeley, National University of Singapore and the University of Kansas Medical Center, scientists from the Woodruff and Marko research groups designed and implemented a novel approach to measure the stiffness of chromosomes.

Using this technique, the scientists discovered a correlation between the stiffness of chromosomes and the reproductive age of a model organism. It is widely accepted that signs of aging of the female reproductive system include errors in chromosome segregation leading to a phenomenon named aneuploidy, a condition where there are more or less chromosomes than is normal for that species. In order to investigate the biophysical properties of chromosomes, scientists utilized this stress technique to determine how “stiff” the chromosomes are for both reproductively aged organisms (where there is a high incidence of aneuploidy) and young organisms (where there is a low incidence of aneuploidy). The correlation, as it was discovered, suggests that as the reproductive age of the organism increases, the stiffness of the chromosome also increases. In fact, chromosomes of reproductively old mice required 2.5 times more force to be stretched than the chromosomes of young mice.

This new finding adds great value to the understanding of cancer biology and age related diseases in which errors of chromosome segregation and aneuploidy play crucial roles.

J Assist Reprod Genet. 2015 Mar 11. [Epub ahead of print] Age-associated alterations in the micromechanical properties of chromosomes in the mammalian egg. Hornick JE1, Duncan FESun MKawamura RMarko JFWoodruff TK.

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