How tiny frogs change their muscles to jump from water to land

Microhyla fissipes starts life as a tadpole swimming in water with a long tail for movement. When it transforms into an adult frog, its tail disappears and strong hind legs take over for jumping on land. Scientists wanted to understand how this tiny frog rebuilds its muscles during this big change. The study compared muscle from the tadpole’s tail to muscle in the adult’s legs. Adult muscle fibers turned out smaller with shorter contractile units called sarcomeres. Researchers also looked at gene activity and chemical processes in both muscle types. They found 4, 103 genes that switched on or off during the shift. Genes that helped with energy use and cell balance increased, while genes for quick sugar burning and cell growth decreased.

Energy production also changed from relying on quick bursts without oxygen to slower, oxygen-based processes. Fifty-seven key metabolites shifted, mostly linked to protein use and insulin control. Two important signaling pathways, AMPK and FoxO, stood out as managers of these changes. Together, these findings show how a small frog’s body adapts its muscles to move from water to land through precise molecular controls.

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