文章来源:未知 文章作者:meng 发布时间:2010-04-12 02:00 字体: [ ]  进入论坛

Using a sensor1 that weighs cells with unprecedented2(空前的) precision, MIT and Harvard researchers have measured the rate at which single cells accumulate(积攒,累积) mass — a feat3(功绩,壮举) that could shed light on how cells control their growth and why those controls fail in cancer cells. The research team, led by Scott Manalis, MIT associate professor of biological engineering, revealed that individual cells vary greatly in their growth rates, and also found evidence that cells grow exponentially(以指数方式) (meaning they grow faster as they become larger).

The new measurement system, reported in the April 11 edition of the journal Nature Methods, is the first technique that can measure cells' mass as they grow over a period of time, ranging from five to 30 minutes. Previous methods for measuring cell growth rates have focused on volume or length measurements, and have not yet exhibited the necessary precision for revealing single cell growth models.

How they did it: The cell-mass sensor, which Manalis first demonstrated in 2007, consists of a fluid-filled microchannel(微通道) etched in(铭记,铭刻) a tiny silicon4 slab5 that vibrates inside a vacuum. As cells flow through the channel, one at a time, their mass slightly alters the slab's vibration6 frequency. The mass of the cell can be calculated from that change in frequency, with a resolution as low as a femtogram(毫微微克) (10-15 grams).

Michel Godin, a former postdoctoral associate in Manalis' lab and co-lead author of the paper, developed a way to trap a cell within the microchannel by precisely7 coordinating8 the flow direction. That enables the researchers to repeatedly pass a single cell through the channel every second or so, measuring it each time it moves through.

The researchers studied four types of cells: two strains of bacteria (E. coli and B. subtilis), a strain of yeast9(酵母) and mammalian(哺乳类动物的) lymphoblasts(淋巴母细胞) (precursors to white blood cells). They showed that B. subtilis cells appear to grow exponentially, but they did not obtain conclusive10 evidence for E. coli. That's because there is so much variation between individual cell growth rates in E. coli, even for cells of similar mass, says Francisco Delgado, a grad student in Manalis' lab and co-lead author of the paper.

If cells do grow exponentially, it means there must be some kind of mechanism11 to control that growth. Otherwise, when cells divide into two slightly different-sized daughter cells, as they often do, the larger cell in each generation would always grow faster than the smaller cell, leading to inconsistent cell sizes.

"If there were no control over the process, the variation in cell size would be all over the map," says Marc Kirschner, professor of systems biology at Harvard Medical School and an author of the paper. However, biologists don't know yet how that control mechanism might work.

Next steps: In their current studies, the researchers are tagging proteins inside the cell with fluorescent12(荧光的) molecules13 that reveal what stage of the cell cycle the cell is in, allowing them to correlate(关联) cell size with cell cycle position. They are also working on a way to add chemicals such as nutrients14, antibiotics15 and cancer drugs to the fluid inside the microchannel, so they can study how those substances affect growth rates.


1 sensor sz7we     
  • The temperature sensor is enclosed in a protective well.温度传感器密封在保护套管中。
  • He plugged the sensor into a outlet.他把传感器插进电源插座。
2 unprecedented 7gSyJ     
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
3 feat 5kzxp     
  • Man's first landing on the moon was a feat of great daring.人类首次登月是一个勇敢的壮举。
  • He received a medal for his heroic feat.他因其英雄业绩而获得一枚勋章。
4 silicon dykwJ     
  • This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
  • A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。
5 slab BTKz3     
  • This heavy slab of oak now stood between the bomb and Hitler.这时笨重的橡木厚板就横在炸弹和希特勒之间了。
  • The monument consists of two vertical pillars supporting a horizontal slab.这座纪念碑由两根垂直的柱体构成,它们共同支撑着一块平板。
6 vibration nLDza     
  • There is so much vibration on a ship that one cannot write.船上的震动大得使人无法书写。
  • The vibration of the window woke me up.窗子的震动把我惊醒了。
7 precisely zlWzUb     
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
8 coordinating fc35d08ba9bb2dcfdc96033a33b9ae1e     
v.使协调,使调和( coordinate的现在分词 );协调;协同;成为同等
  • He abolished the Operations Coordinating Board and the Planning Board. 他废除了行动协调委员会和计划委员会。 来自辞典例句
  • He's coordinating the wedding, and then we're not going to invite him? 他是来协调婚礼的,难道我们不去请他? 来自电影对白
9 yeast 7VIzu     
  • Yeast can be used in making beer and bread.酵母可用于酿啤酒和发面包。
  • The yeast began to work.酵母开始发酵。
10 conclusive TYjyw     
  • They produced some fairly conclusive evidence.他们提供了一些相当确凿的证据。
  • Franklin did not believe that the French tests were conclusive.富兰克林不相信这个法国人的实验是结论性的。
11 mechanism zCWxr     
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
12 fluorescent Zz2y3     
  • They observed the deflections of the particles by allowing them to fall on a fluorescent screen.他们让粒子落在荧光屏上以观察他们的偏移。
  • This fluorescent lighting certainly gives the food a peculiar color.这萤光灯当然增添了食物特别的色彩。
13 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
14 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
15 antibiotics LzgzQT     
n.(用作复数)抗生素;(用作单数)抗生物质的研究;抗生素,抗菌素( antibiotic的名词复数 )
  • the discovery of antibiotics in the 20th century 20世纪抗生素的发现
  • The doctor gave me a prescription for antibiotics. 医生给我开了抗生素。
TAG标签: cells sensor cancer