Lions and hyenas compete for food and will kill each other if they get the chance, but studying their power struggle is difficult — they roam over wide landscapes where it’s hard for scientists to follow them, and their most active hours are in darkness or twilight. Now scientists have taken advantage of GPS collars to plot the movements of different hyenas and lions, shedding new light on their competition. It’s well known that hyenas scavenge from lion kills, which gave scientists cause to think that hyenas followed lions through the bush. But this new evidence shows that the direction of pursuit runs the other way: male lions in particular approach hyenas when they encounter them, and hyenas retreat.

As part of an effort to understand the molecules and mechanisms that regulate transendothelial migration in different vascular beds of the body, researchers focused on the blood vessels of the retina, part of the blood-brain barrier. Transendothelial migration is the process by which white blood cells migrate out of the blood into tissue to reach sites of inflammation. The researchers found that white blood cells pass through the blood-retinal barrier via the same mechanism as they do throughout the rest of our body. This study in The American Journal of Pathology, published by Elsevier, provides new insights into how eye inflammation develops and could lead to better targeted treatment options.