Learn how quickly previously trained muscles bounce back after inactivity; and how a black hole made a star explode. Previously trained muscles bounce back after inactivity by Grant Currin Seaborne, R. A., Strauss, J., Cocks, M., Shepherd, S., O’Brien, T. D., van Someren, K. A., Bell, P. G., Murgatroyd, C., Morton, J. P., Stewart, C. E., & Sharples, A. P. (2018). Human Skeletal Muscle Possesses an Epigenetic Memory of Hypertrophy. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-20287-3 Prior training can accelerate muscle growth even after extended idleness. (2021, August 18). EurekAlert! https://www.eurekalert.org/news-releases/925769 Wen, Y., Dungan, C. M., Mobley, C. B., Valentino, T., von Walden, F., & Murach, K. A. (2021). Nucleus Type-Specific DNA Methylomics Reveals Epigenetic “Memory” of Prior Adaptation in Skeletal Muscle. Function, 2(5). https://doi.org/10.1093/function/zqab038 Episode about previous research: https://www.curiositydaily.com/individuals-really-can-slow-climate-change-muscle-memory-is-real-and-penguin-waddles/ A black hole collided with a star and made it explode in a merger-triggered supernova by Briana Brownell Dong, D. Z., Hallinan, G., Nakar, E., Ho, A. Y. Q., Hughes, A. K., Hotokezaka, K., Myers, S. T., De, K., Mooley, K. P., Ravi, V., Horesh, A., Kasliwal, M. M., & Kulkarni, S. R. (2021). A transient radio source consistent with a merger-triggered core collapse supernova. Science, 373(6559), 1125–1129. https://doi.org/10.1126/science.abg6037 Stellar collision triggers supernova explosion. (2021, September 2). EurekAlert! https://www.eurekalert.org/news-releases/927166 A Black Hole Triggers a Premature Supernova – First Observation of a Brand-New Kind of Supernova. (2021, September 5). A Black Hole Triggers a Premature Supernova – First Observation of a Brand-New Kind of Supernova. SciTechDaily. https://scitechdaily.com/a-black-hole-triggers-a-premature-supernova-first-observation-of-a-brand-new-kind-of-supernova/ Plait, P. (2021, September 6). So, a star may have eaten a black hole and exploded. SYFY WIRE; SYFY WIRE. https://www.syfy.com/syfywire/so-a-star-may-have-eaten-a-black-hole-and-exploded Follow Curiosity Daily on your favorite podcast app to learn something new every day withCody Gough andAshley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Learn how quickly previously trained muscles bounce back after inactivity; and how a black hole made a star explode.
Previously trained muscles bounce back after inactivity by Grant Currin
A black hole collided with a star and made it explode in a merger-triggered supernova by Briana Brownell
Follow Curiosity Daily on your favorite podcast app to learn something new every day with Cody Gough and Ashley Hamer. Still curious? Get exclusive science shows, nature documentaries, and more real-life entertainment on discovery+! Go to https://discoveryplus.com/curiosity to start your 7-day free trial. discovery+ is currently only available for US subscribers.
Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/muscles-remember-training-and-a-black-hole-made-a-star-explode
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about how quickly previously trained muscles bounce back after inactivity; and how a black hole made a star literally explode. CODY: Let’s satisfy some curiosity.
Previously trained muscles bounce back after inactivity by Grant Currin (Cody)
It’s hard to start working out, but incredibly easy to stop — just ask your average ex-high school athlete or a person who, I don’t know, has lived through a pandemic. Or… me. Specifically. Well here’s the good news: it’s a lot easier to build muscles you once had than it is to train for the first time. And researchers in Arkansas have uncovered a little bit more about why that’s the case.
In the last few years, researchers have made some exciting discoveries about this phenomenon. Like, a study in 2018 had men undergo a grueling resistance-training program, then stop for a few weeks, then start their workouts again. Researchers biopsied their muscles and found that certain locations on their DNA were marked with chemical “tags” that determined how they were expressed — and those tags seemed to help them get stronger, faster the second time around.
But the method those researchers used was pretty general — there was no way to know whether the DNA they were looking at came from the specialized nuclei of muscle cells or from cells outside of the muscle. So these Arkansas researchers decided to zoom in directly on muscle DNA. And for that, they used mice.
For the experiment, one group of mice spent eight weeks training on a wheel, then took about three months off.
After the break, it was back on the wheel. But this time, more mice joined in. The second group was identical to the first with one key difference: they hadn’t trained before. Both groups trained for four weeks. Then the coaches-slash-researchers euthanized them and took samples of the muscles the mice had built.
As expected, the mice with a history of training had a way easier time putting on muscle than mice that were starting from scratch. What’s more, the researchers found the same molecular “tags” as previous research. In this case, they led to the expression of genes involved in muscle growth and adaptation. And those tags remained when the mice stopped exercising. Most importantly, there were more of these tags in the specialized muscle DNA than there were in DNA found in cells outside of the muscle.
In other words, it was easier to re-grow muscle because muscle cells that had been trained in the past were actually storing a quote-unquote “memory” of that exercise regimen. Those memories made it easier for the cells to start growing again when the mice resumed exercising.
So if your running shoes have gotten a little dusty, don’t despair. And if you’re thinking about taking up a new activity for the first time, don’t let the fear of quitting stop you. Progress isn’t lost as quickly as you might think.
A black hole collided with a star and made it explode by Briana Brownell (Ashley)
A black hole collided with a star and made it explode. And scientists caught it in the act for the very first time.
Most stars form in duos called binary pairs, and usually, one of the stars is larger than the other. As this larger star attracts mass from the smaller companion, the larger star gets even larger still.
Eventually, the large star explodes in a supernova, leaving behind something really, really dense: either a neutron star or a black hole. It’s just a few kilometers across, but it’s got a lot of mass, and it’s ready to do some real damage.
This tiny, massive object is pulled closer and closer to its old companion until it’s sucked right into the star’s gaseous interior. That’s when the fireworks really start to fly. All that mass sprays the gas into space, and that gas surrounds the pair with a ring-shaped cloud. But the object keeps going. It gets closer and closer to the star’s core, which disturbs the energy-intensive fusion reaction that keeps the star burning. At that point, the star’s core collapses and the star explodes in its own supernova with a bright flash of high-energy X-rays. As the exploding star’s remains hurtle outward into space, they eventually reach the ring of gas. This second collision ends in a burst of radio waves.
This awe-inspiring event is called a merger-triggered supernova. And although it’s a well-established process in astrophysics, it had never been observed — until recently.
The difficulty comes down to timing: the initial X-ray burst happens really fast, but that second radio burst can take years to happen. That means you have to find the right series of observations years apart.
So, a team led by a researcher at CalTech decided to work backwards: first they found the radio burst, then they matched it with observations of X-ray bursts in the past.
In 2017, a project called the Very Large Array Sky Survey found a radio signature that matched what they were after. The team cross-referenced that signature with observations from the Keck Observatory where they found evidence of hydrogen gas in the same place. Just what you’d expect to see before the explosion.
Finally, they cross-referenced the results from the International Space Station’s MAXI detector. And on August 14, 2014, they found a burst of X-rays coming from the same position: evidence of the initial supernova explosion. This emission only lasted 15 seconds, but the radio waves from the exploding star hitting the gas cloud took three years to show up.
But the legend is even longer than that. The first part of the story, when the remnant moved into the atmosphere of its companion star? It happened about three hundred years earlier.
That’s a blink of an eye in stellar terms. But for us, it’s a saga that lasts for generations. Thanks to this discovery, we can now close the book on this adventure.
RECAP
Let’s recap today’s takeaways
1. ASHLEY: It's a lot easier to build muscles you once had than it is to train for the first time. That’s because DNA in your muscle cells retain “memories” of previous training, and add little molecular tags that express the genes for muscle growth and adaptation so you can do it better the second time around.
2. CODY: A black hole collided with a star and made it explode in what’s called a merger-triggered supernova. Although it’s a well-established process in astrophysics, it had never been observed until recently.
[ad lib optional]
ASHLEY: Today’s writers were Grant Currin and Briana Brownell.
CODY: Our managing editor is Ashley Hamer.
ASHLEY: Our producer and audio editor is Cody Gough.
CODY: [AD LIB SOMETHING FUNNY] Join us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!