Gill-on-a-chip illuminates evolution

Abstract

Physiology![Figure][1] Gill lamellae of the cichlid fish. PHOTO: DENNIS KUNKEL MICROSCOPY, INC/VISUALS UNLIMTED, INC. Fish gills are natural microfluidic devices that evolution has optimized to extract oxygen from water. The spacing between the lamellae, the tiny protrusions that cover gill filaments, varies little between fish of wildly different sizes, which suggests that this spacing is important for gill function. To test this, Park et al. developed a mathematical model for oxygen transfer across lamellae. Indeed, they found, lamellae spacing is critical for gill function, as is the way fish pump water through their gills. The researchers then tested their model against an artificial gill—a microfluidic chip where oxygen diffuses across synthetic membranes. When they varied the distance between the membranes, the artificial gill extracted the most oxygen with membrane spacing similar to that of lamellae in fish gills. Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1403621111 (2014). [1]: pending:yes