Warm-Blooded Animals Lost Ability to Heal the Heart
This is science Americans. Sixty seconds science. I'm Christopher Dodd yada. It sounds like a witch's recipe gathered the hearts of offense lizard, a Little Brown bat and naked tailed Armadillo and dozens of others we try to get them from zoo. But I'll fortunate we the student walkout very well. We couldn't get any samples even when dynamo die could get heart developmental biologist at the university of California, San Francisco, he says they had more success obtaining specimens from the jars of natural history, museums, but the reason for this biological scavenger hunt Wong and his colleagues wanted to examine the number of chromosomes contained in heart cells across the animal kingdom, because there's a curious phenomenon in our hearts, which is that most of the human body cells are diploid, meaning two sets of chromosomes one from each parent, but the lion's share of our heart cells are actually Polly -ployed, meaning two or more copies for mom two or more copies from dad. What one and his team found looking at that collection of hearts is that the proportion of Polly played cells in a heart goes up as you go from fish to lizards to him fibia NHS to transitional species like platypuses to mammals, the reason that finding might matter to us is that recent studies in mice, and zebra fish of shown that hearts with more diploid cells, like zebra, fishes are actually able to regenerate and heal themselves. Hearts with more. Polly -ployed sells like mice and humans cannot. So what makes a heart have more Polly played cells and thus less chance of regenerating costume. Oh costume. But one answer once team found is that thyroid hormone, the same hormone that regulates metabolism and makes us warm blooded creatures might be to blame. Because when they added extra thyroid hormone disease officials tanks. They're tiny hearts were no longer able to regenerate. And conversely when they engineered mice to have hearts that were insensitive to thyroid hormone, the mouse hearts could regenerate back after injury heart function, which is mainly measure contracted the of the heart. We can see to heart function improve or would tie off the injury. Welcome to my cannot improve. The results are in the journal science as for fixing human hearts, perhaps manipulating thyroid hormone levels could be a start. We know regularly in federal home alone, not sufficient to cure, heart disease. Lisa for promote a har-, Richard. And completely. And if we can figure out other major regulator of this process, we might be in a. Better shape. Thanks for listening for scientific American sixty seconds science. I'm Christopher Don. Yata?