F(ly)1

In order to investigate how sperm of two different males compete within the reproductive tract of the female, a researcher at Syracuse University used a fluorescent tag to be able to directly visualize the movement of individual sperm. She engineered male flies whose sperm was loaded with proteins that glow either red or green. By following these glows with a special microscope, video captured the sperm racing around the female’s genital tract at high speed, like miniature race cars.