This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
Every day, you produce one to two liters of spit. It kickstarts digestion and helps you swallow. And it helps prevent bacterial infection in your mouth.
"But that still seemed like a lot of energy put into something if it's only going to do that small task." Esther Bullitt, a biophysicist at the Boston University School of Medicine. "And we wondered whether there was something else it was doing as well, if maybe it had a farther reach than just preventing infections in the mouth."
So she and her team looked farther down the pipes—at whether certain proteins in spit might also disrupt the work of bad bugs in the gut. They grew cells taken from the small intestine of a 51-year-old woman. They also grew a batch of pathogenic E. coli bacteria, the kind that cause traveler's diarrhea. The E. coli have hair-like extensions, called pili, that grab onto the intestinal cells. But fewer of the E. coli were able to successfully attach to the intestinal cells when a particular saliva protein, called histatin-5, was hanging around.
You can think of the E. coli like pirate ships, trying to dock at a port. What the histatin-5 does is stop the pirate ships, the bad bugs, from using their ropes—the pili—to dock. Because if you can't bind, then you can't start an infection.So no adhesion, no infection, no disease."
The study is in The Journal of Infectious Diseases.
The salivary protein can be chemically synthesized; stored as a powder; and dissolved in water. And presumably, the resulting liquid is safe. "You know that your body tolerates it, because you swallow one to two liters of it every day." No word yet on whether it might someday be available at the drugstore. But the good news is: you're already swallowing some right now.
Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.
人类每天都会产生一到两公升唾液 。唾液能促进消化并帮助吞咽 。同时也有助于防止口腔细菌感染 。
“但是，如果只是进行这些小任务，那似乎投入了太多精力 。”波士顿大学医学院的生物物理学家艾丝特·布利特说到 。“如果唾液的功能不只是防止口腔感染，我们想知道其是否还有其他用途 。”
因此，她和团队进行了深入研究，想弄清楚唾液中某些蛋白质是否也会干扰肠道内有害细菌的破坏 。他们从一名51岁女性的小肠中提取了细胞，并对细胞进行培养 。他们还培养了一批致病性大肠杆菌，这是导致旅行者腹泻的一种细菌 。大肠杆菌有被称为“菌毛”的毛状突起，这种突起能够紧紧抓住肠道细胞 。但是，当被称为“人富组蛋白”的特殊蛋白在周围时，附着在肠道细胞上的大肠杆菌数量就会减少 。
你可以把大肠杆菌想象成试图停靠在港口的海盗船 。“人富组蛋白”所做的就是阻止海盗船即有害细菌，使它们无法用绳子即“菌毛”来停靠到码头 。“因为如果你不能粘合，那就会开始感染 。因此，没有粘连，就没有感染，也就没有疾病 。”
唾液蛋白质可以化学合成；以粉末形式储存；并溶于水 。据推测，所得到的液体是安全的 。“你知道你的身体能与它共存，因为你每天要吞下1至2升这种蛋白质 。”至于未来能否在药店买到这种蛋白质，目前还不得而知 。不过好消息是：你现在已经在吞咽了 。
谢谢大家收听科学美国人——60秒科学 。我是克里斯托弗·因塔利亚塔 。
1. a batch of 一批；一组；一群；
Our company has got a batch of orders.
2. be able to do sth. 可以…的，能够…的；
You must be able to speak French for this job.
3. hang around 经常和…在一起；
It's dangerous for Natalie and Clara if I hang around.
4. stop sb. from doing sth. 阻止；阻碍；阻拦；防止；
You can't stop people from saying what they think.