Tears aren’t just an outlet for when our emotional cup overflows, they play a crucial role in protecting our rather exposed eyes. For example, tear fluid has long been known to restrict the activity of Pseudomonas aeruginosa - a bacterium known for its antibiotic resistance that can cause problems from hot tub folliculitis to sight-threatening diseases. To find out how exactly it helps, researchers compared P. aeruginosa’s behaviour in a normal environment (left) to when in contact with tear fluid (right), and found that its motility was greatly impaired. Dark blue shows slow bacterial movement while light green and yellow shows rapid. A protein in tears called DMBT1 slows bacteria by interfering with their ‘twitching’ ability. This halts their spread across the eye, limiting the impact of infection. Understanding this shows how our bodily fluids fight infection, and could point to new medical approaches.
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