时域信息使人类像人类
文章来源:未知 文章作者:enread 发布时间:2016-04-22 08:08 字体: [ ]  进入论坛
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Researchers believe that genetically1 modified bacteria can help explain how a developing animal keeps all of its parts and organs in the same general proportions as every other member of its species. In 1952, Alan Turing mathematically demonstrated how the nearly endless variety of patterns seen in nature -- spots on cheetahs3 or the distinctive4 coats of leopards5, for example -- could be explained by chemicals spreading and interacting by simple rules. Many scientists, however, remained unconvinced, and believed there must be more to the story.
 
Now, Duke University researchers have discovered another way that patterns can form -- through the use of a ticking clock. By combining two chemical signals with a few variables, timing6 cues emerge. And these timing cues can not only create patterns -- they can also make sure these patterns have roughly the same proportions from one colony to the next.
 
In a study published on April 21 in the journal Cell, Lingchong You, the Paul Ruffin Scarborough Associate Professor of Engineering at Duke University, introduced a new genetic2 circuit into a population of bacteria. You programmed bacteria to produce a protein called T7RNAP (tagged fluorescent7 blue), which activates8 its own expression in a positive feedback loop. 
 
As the bacterial9 colony grows and produces more T7RNAP, it also produces a chemical that triggers the production of a protein called T7 lysozyme (tagged fluorescent red), which inhibits10 the production of T7RNAP. Wherever the two molecules11 interact, purple patterns appear in the colony.
 
Because bacteria toward the outer edge of the colony are more active than those in the interior, this system causes a purple ring to appear like a bullseye. You and his colleagues discovered that they could control its thickness and how long it took for the bullseye to appear by varying the size of the growing environment and amount of nutrients12 provided.


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1 genetically Lgixo     
adv.遗传上
参考例句:
  • All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
  • Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物
2 genetic PgIxp     
adj.遗传的,遗传学的
参考例句:
  • It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
3 cheetahs 49fe48184ec612a4c6ab48e2544552ef     
n.(奔跑极快的)非洲猎豹( cheetah的名词复数 )
参考例句:
  • Unlike lions or cheetahs, leopards are secretive, solitary cats. 花豹不像狮子或印度豹,是属于较神秘而隐居的大猫。 来自互联网
  • Among this lot are cheetahs, lions, leopards, rhinoceroses, spotted hyenas and elephants. 印度豹、狮子、花豹、犀牛、斑点土狼、大象等,都是此地的居民。 来自互联网
4 distinctive Es5xr     
adj.特别的,有特色的,与众不同的
参考例句:
  • She has a very distinctive way of walking.她走路的样子与别人很不相同。
  • This bird has several distinctive features.这个鸟具有几种突出的特征。
5 leopards 5b82300b95cf3e47ad28dae49f1824d1     
n.豹( leopard的名词复数 );本性难移
参考例句:
  • Lions, tigers and leopards are all cats. 狮、虎和豹都是猫科动物。 来自《简明英汉词典》
  • For example, airlines never ship leopards and canaries on the same flight. 例如,飞机上从来不会同时运送豹和金丝雀。 来自英语晨读30分(初三)
6 timing rgUzGC     
n.时间安排,时间选择
参考例句:
  • The timing of the meeting is not convenient.会议的时间安排不合适。
  • The timing of our statement is very opportune.我们发表声明选择的时机很恰当。
7 fluorescent Zz2y3     
adj.荧光的,发出荧光的
参考例句:
  • 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。
8 activates 78ec2b8b23e0120508757d953f1013d1     
使活动,起动,触发( activate的第三人称单数 )
参考例句:
  • Activates the window and displays it in its current size and position. 激活窗口,保持当前的大小及位置不变。
  • Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。
9 bacterial dy5z8q     
a.细菌的
参考例句:
  • Bacterial reproduction is accelerated in weightless space. 在失重的空间,细菌繁殖加快了。
  • Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。
10 inhibits 7fbb1ac5e38d9e83ed670404679a2310     
阻止,抑制( inhibit的第三人称单数 ); 使拘束,使尴尬
参考例句:
  • A small manufacturing sector inhibits growth in the economy. 制造业规模太小有碍经济增长。
  • His bad English inhibits him from speaking freely. 他英语学得不好,这使他不能表达自如。
11 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • 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。
12 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
参考例句:
  • 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》
TAG标签: bacteria timing cues
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