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. Author manuscript; available in PMC: 2023 Sep 1.
Published in final edited form as: Trends Parasitol. 2022 Jun 13;38(9):791–804. doi: 10.1016/j.pt.2022.05.012

Figure 3. Meiotic sex ratio distortion in Aedes aegypti (A) and Anopheles gambiae (B).

Figure 3.

A) The naturally occurring meiotic drive distorts sex ratio in Aedes aegypti. It is comprised of a male-linked distorter (D) allele that targets drive sensitive alleles on the m chromosome for breakage during spermatogenesis [99]. Although the mechanism remains unknown, targeting of the sensitive alleles results in m chromosome breakage and disrupts the formation of m chromosome-bearing sperm, favoring transmission of the M-bearing (and D-bearing) sperm and causing male-bias in the progeny. B) An engineered X-shredder in An. gambiae (purple line on one of the autosomes) uses either an I-PpoI homing endonuclease or the RNA-guided Cas9 endonuclease (depicted as Cas9) to target an rDNA gene cluster located exclusively on the X chromosome. This reduces transmission of the X-bearing sperm and results in a sex ratio bias in the following generation. Since the shredder allele is not on the sex chromosome, the inheritance of the shredder allele follows Mendelian segregation and is not sex biased.