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  • Itll soon be summer here in the northern hemisphere, and winter for those of you on

  • the other half of the planet.

  • Of course, plenty of things change with the seasons: the weather, the number of daylight

  • hours, whether or not you have school...

  • And according to new research, there are other things that change, as well- like your genes.

  • For a long time, doctors, patients, and researchers have noticed that some diseases, like heart

  • disease, type 1 diabetes, and rheumatoid arthritis seem to get worse during the winter. But they

  • weren’t sure why.

  • Now, it looks like there’s a very good reason: genes associated with your immune system seem

  • to change expression -- that is, basically, to turn off and on -- based on the season.

  • Researchers from the UK and Germany studied the genomes of more than 16,000 people from

  • all over the world, using blood and fat samples that had been collected at different times

  • of year.

  • Since your genes code for particular proteins, if a sample had more of a certain kind of

  • protein at a specific time of year, that meant the gene associated with it was more active.

  • And the patterns that showed up in the subjects showed some clear similarities.

  • Out of nearly 23,000 genes, over 5,000 were more active certain times of year.

  • And the patterns were actually reversed in people who lived in different hemispheres.

  • So genes that were more active in a German during December were also more likely to be

  • active in an Australian in June.

  • One immune system gene, called ARNTL, is known to suppress inflammation in mice, and it turned

  • out to be more active in people during the summer.

  • This could explain why some autoimmune diseases, like rheumatoid arthritis, tend to flare up

  • in winter -- because that’s when the genes that help reduce inflammation aren’t expressed

  • as strongly.

  • Similarly, genes that code for the antibodies that fight diseases like yellow fever, influenza,

  • and meningitis were found to be more active during the winter.

  • Now that makes some sense, because winter is flu season, but it also means that winter

  • may be most effective time to vaccinate against these diseases, so vaccines can evoke the

  • best possible response from your immune system.

  • As for the gene that showed the strongest seasonal preference -- geneticists know which

  • protein it codes for, but they have no idea what it does.

  • So, yeah, we have a lot more to learn, but the results suggest that our bodies may be

  • more in tune with our yearly trek around the sun than we’d thought.

  • Speaking of genetics, another team of scientists has been investigating an animal that’s

  • taught us a whole lot about the field: the famous fruit fly.

  • And it seems that they experience fear?

  • It’s kind of tough to identify emotions in animals like flies, because ... how would

  • you know fly-fear if you saw it?

  • But a group of American researchers has translated fear into a few basic behaviors, so that animals

  • responses could be studied without assigning them subjective human feelings, like dread

  • or anxiety.

  • The scientists arrived at behaviors like whether an animal’s response was persistent, meaning

  • that it lasted for a while, or if it was scalable, in which case, repeated stimuli would cause

  • a greater response.

  • They called these traits emotion primitives -- sort of like the primal components of emotions

  • that some animals may have in common.

  • To test for those components, the team put groups of fruit flies into well-lit containers,

  • and then passed an object over them to cast a shadow, just like a bird or a rodent would

  • if it were approaching to prey on them.

  • Then, they observed the fliesresponses.

  • Sometimes, the flies just froze -- a defensive reflex, which makes a lot of sense.

  • But other times, the flies started hopping around erratically when the shadows passed

  • over them -- and the more the shadow returned, the more agitated they seemed to become.

  • The researchers then tried the experiment on flies as they were feeding. And they found

  • that flies not only abandoned their food when the shadow approached, but the more often

  • the shadow came by, the longer they took to return to their food.

  • So, the flies responded to these repeated threats, in ways that were both persistent

  • and scalable, which -- to the researchers, at least -- is a lot like what we call fear.

  • But other than making everyone feel bad for a bunch of fruit flies, what does this accomplish?

  • Well, the researchers want to study the biological, and evolutionary, origins of fear. And since

  • fruit flies and humans have about 60 percent of their genomes in common, studies like this

  • can be useful in researching, and eventually treating, prolonged states of anxiety, fear,

  • and other emotional disorders in people.

  • So, while youre making out your thank you cards for the poor fruit flies, allow me to

  • thank you for watching SciShow News, which is brought to you by our patrons on Patreon.

  • If you want to help us keep making this show, you can go to patreon.com/scishow. And don’t

  • forget to go to youtube.com/scishow and subscribe!

Itll soon be summer here in the northern hemisphere, and winter for those of you on

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季節の遺伝子と恐怖の科学 (Seasonal Genes & The Science of Fear)

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    SylviaQQ に公開 2021 年 01 月 14 日
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