Creation of a new Drosophila melanogaster X chromosome balancer, First Multiple 8 ( FM8 ), using the CRISPR/Cas9 gene-editing system.

Balancer chromosomes contain multiple inversions that work to suppress crossing over and prevent recovery of most recombinant chromosomes, allowing for alleles to be kept long-term without selection. These balancers are incredible tools, but some alleles within larger inverted segments are still lost to rare double crossover events between the balanced and balancer chromosomes. This study details a new methodology of producing balancer chromosomes using CRISPR/Cas9 gene editing technology to create new inversions within the largest segment of the common X chromosome balancer, FM7c. We were able to create a new X chromosome balancer, FM8, and anticipate that this process can be used to not only create other balancers in Drosophila melanogaster, but other model organisms as well.