In this week's Science, a researcher from Stony Brook University discusses how residual genetic material found in the ocean — so-called environmental DNA (eDNA) — can be used to study hard-to-find marine animals. While current methods rely on capturing or visually identifying the animals, eDNA can be obtained from skin cells, scales, secretions, and other tissues that remain in waters for weeks. "Overall, eDNA analysis is more effective, safe, and feasible than other noninvasive sampling techniques and conventional capture procedures," Stony Brook’s Ellen Pikitch writes. Still, eDNA is limited to informing about attributes that are discoverable from genetic material. As such, it will complement — not replace — other research approaches when it comes to studying subjects such as life stage, size, age, growth rates, and the relationships between organisms and their environment.
And in Science Advances, a team from Harvard Medical School identifies a gene on the X chromosome that appears to protect against bladder cancer in women, helping explain why men are far more likely to have the disease. Using sex-reversed mice, the scientists find that sex chromosomes amplify the effects of sex-hormones in the animals with bladder cancer. They also discovered that the X-linked lysine demethylase 6A (KDM6A) gene is sexually dimorphic, and its knockdown increases bladder cancer risk in female mice. When the investigators analyzed genomic and clinical data from 412 bladder cancer patients, they found that mutations or reduced expression of human KDM6A predicts poor prognosis of female bladder cancer patients.