Y chromosome labelling in mitotic chromosomes from Anopheles gambiae testis. In this image, two Anopheles gambiae Y-linked satellite elements, AgY53B (Green) and AgY53A (Red), have been stained using DNA FISH on male gonial cell metaphase chromosomes. The CRISPR/Cas9 system was used to specifically target the satellite AgY53B during male meiosis, causing extensive damage to the Y chromosome. This damage results in Y-bearing sperm being unable to fertilize eggs while X-bearing sperm remain intact and viable. As a result, a strong bias toward female offspring is observed in the progeny of transgenic males. See Vitale et al.

Image Credit: Matteo Vitale