'Turbocharged' Mitochondria Power Birds' Epic Migratory Journeys

Summary

Coulson, who was a graduate student with Staples and Guglielmo at the time, led a study on the yellow-rumped warbler, a songbird that migrates between Canada, where it nests, and its wintering grounds in the United States, Mexico and the Caribbean. First, during the birds’ fall migration, they captured the southbound songbirds and brought them into the lab. There, they managed the birds’ exposure to light and darkness to create two laboratory groups of “migratory” and “nonmigratory” warblers. Then they looked for differences in the birds’ mitochondria. The researchers removed the birds’ flight muscles (which required euthanizing them) and separated out the mitochondria. Then they did lab tests to measure the organelles’ oxygen consumption, which serves as a proxy for how much ATP mitochondria can produce to contract those muscles. Is the performance of the mitochondria different in birds that are migratory, compared to those that are not? “We hypothesize that when birds are migrating, they have a really high demand on their flight muscle in terms of providing energy for muscle contractions,” Coulson said. “Some of these birds can be flying for up to several hours overnight at a really high exercise intensity.” The scientists found that birds experiencing the “migration” condition had more mitochondria, and that those mitochondria had a greater capacity to make energy, compared to those in the “nonmigratory” birds. This suggested that during migration, the birds’ mitochondria are “turbocharged,” Coulson said. Then, after the journey is done, the mitochondrial landscape reverts to its usual state. The researchers published their findings in the Journal of Experimental Biology in 2024. “All those turbocharged mitochondria become regular-charged mitochondria, [and] they get rid of the excess ones,” Coulson said. “That way, they can stop potentially wasting energy on traits that they no longer need for that time of the year.” The Mighty MitoMobile Emma Rhodes, a graduate...