Investigators have employed mutant mice to study how the accumulation of genetic errors is managed during egg and sperm formation.

That’s why Sloan Kettering Institute (SKI) researchers used a strain of mutant mice as a means to uncover new clues about the process of meiosis, which forms eggs and sperm (also known as germ cells). The investigators learned how breaks in DNA can lead to unanticipated types of harmful mutations. Understanding how mutations arise in germ cells is important because they can cause miscarriages and genetic diseases. The research was published November 17, 2021, in Cell.

«This research has enabled us to learn more about meiosis at the molecular level,» says first author Agnieszka Lukaszewicz, a senior research scientist working in the lab of Maria Jasin, a member in SKI’s Developmental Biology Program. «We have new insights about what happens when something goes wrong.»

Managing DNA Breaks to Prevent Errors

Thanks to meiosis, children inherit an equal amount of genetic material from each parent. But each sperm or egg cell contains only half of the parent’s DNA. After an egg is fertilized, the two halves come together to create an embryo with a full set of chromosomes.

A crucial part of meiosis occurs when both strands of DNA break in the same place and then are repaired by a process called recombination. About 300 of these double-strand breaks occur around the genome during the normal formation of egg and sperm cells. The breaks ensure that the parents’ DNA can be halved, while also resulting in genetic variation in the offspring.

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Materials provided by Memorial Sloan Kettering Cancer Center. Note: Content may be edited for style and length.