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At that point we call it a memory T-cell because it’s learned to recognize a protein marker that identifies this particular kind of bacterium.
在那個階段，我們稱它為記憶性T細胞，因為它學會了辨認代表著這種細菌的蛋白標志物。
But before it’s learned to recognize any particular protein from outside the body, we call it naive. Okay?
但是在它學會辨認任何來自身體之外的具體蛋白質之前，我們稱它們?yōu)橛字尚停藛幔?/div>
Yeah, I get it.
嗯，我懂了。
There is a lot of biochemistry involved that we’ll get into in the next lecture.
這其中涉及了很多生物化學知識，我們下堂課會講到的。
But your question reminds me about a study that some of my colleagues are doing, it relates to caloric restriction.
但是你的問題讓我想起了我的一些同事正在做的一項研究，它和卡路里限制有關。
Caloric? Like calories in the food we eat.
卡路里的？就像我們吃的食物中的卡路里一樣？
Exactly! We are talking about the sugars, carbohydrates, fats that our bodies burn to get energy which we measure in calories.
沒錯！我們講的是我們身體燃燒以獲取能量的糖分、碳水化合物、脂肪，這些我們都是用卡路里來計算的。
Okay, let’s back up a little. Back in the 1930s, a nutritionist at Cornell University put mice on a severely restricted diet.
好了，我們往回講一點。在過去二十世紀三十年代的時候，一位Cornell大學的營養(yǎng)學家給老鼠制定了一個嚴格限制的食譜。
He gave each mouse in one group 30% less food, or more precisely, 30% fewer calories than the mice in the other group which ate a normal amount.
他少給了一組里的每只老鼠30%的食物量，或者更確切地說，比另一組正常食量的老鼠少30%的卡路里。
And the result, the underfed mice lived much longer than the normally fed ones.
結果是，食物不足的老鼠比正常喂養(yǎng)的老鼠活得久得多。
