Cell biology: Selfish B chromosomes unleashed by a dysfunctional chromosome segregation system
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P. Ferree,
Current Biology,
33:R431-R434.
2023.
A study in the fruit fly Drosophila melanogaster shows that a defective chromosome segregation system allows non-essential B chromosomes to transmit at higher-than-Mendelian frequencies. More related to this: B chromosomes reveal a female meiotic drive suppression system in Drosophila melanogaster
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Selfish genetic elements use a myriad of mechanisms to drive their inheritance and ensure their survival into the next generation, often at a fitness cost to its host.(1)(,)(2) Although the catalog of selfish genetic elements is rapidly growing, our understanding of host drive suppression systems that counteract self-seeking behavior is lacking. Here, we demonstrate that the biased transmission of the non-essential, non-driving B chromosomes in Drosophila melanogaster can be achieved in a specific genetic background. Combining a null mutant of matrimony, a gene that encodes a female-specific meiotic regulator of Polo kinase,(3)(,)(4) with the TM3 balancer chromosome creates a driving genotype that is permissive for the biased transmission of the B chromosomes. This drive is female-specific, and both genetic components are necessary, but not individually sufficient, for permitting a strong drive of the B chromosomes. Examination of metaphase I oocytes reveals that B chromosome localization within the DNA mass is mostly abnormal when drive is the strongest, indicating a failure of the mechanism(s) responsible for the proper distribution of B chromosomes. We propose that some proteins important for proper chromosome segregation during meiosis, like Matrimony, may have an essential role as part of a meiotic drive suppression system that modulates chromosome segregation to prevent genetic elements from exploiting the inherent asymmetry of female meiosis.More related to this:
