探究紫锥花谜一般的起源
文章来源:未知 文章作者:meng 发布时间:2010-03-07 01:59 字体: [ ]  进入论坛
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An Agricultural Research Service (ARS) scientist is helping1 to sort through the jumbled2(乱七八糟的) genetics of Echinacea(紫锥花属) , the coneflower(金花菊) known for its blossoms--and its potential for treating infections, inflammation, and other human ailments(疾病,小病) . Only a few Echinacea species are currently cultivated as botanical(植物学的) remedies(救济方法) , and plant breeders(植物育种家) would like to know whether other types also possess commercially useful traits. ARS horticulturist(园艺家) Mark Widrlechner, who works at the ARS North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa, is partnering in research to find out how many distinct Echinacea species exist. Previous studies have put the number between four and nine species, depending on classification criteria4(分类标准) .

Working with Iowa State University scientists, Widrlechner selected 40 diverse Echinacea populations for DNA5 analysis from the many populations conserved6 at the NCRPIS. Most of these Echinacea populations were found to have a remarkable7 range of genetic3 diversity.

DNA analysis suggested that when much of North America was covered with glaciers8(冰川) , Echinacea found southern refuges on both sides of the Mississippi River. But when the glaciers receded9(后退,减弱) after thousands of years, the groups came together as they moved northward10 and began to hybridize(杂交,混合) , which might have blurred11 previous genetic distinctions.

The research team also analyzed12 the same populations for chemical differences in root metabolites(代谢物,代谢分子) . These metabolites, which are often essential for survival and propagation(传播,繁殖) , can vary widely among species and may have benefits for human-health.

Using this approach, researchers were able to identify clear distinctions among all 40 populations. These distinctions were organized into three composite profiles that accounted for almost 95 percent of the metabolite variation among the populations.

Additional analysis of metabolite variation indicated that the populations grouped together in ways that aligned13 well with earlier Echinacea species assignments that were based on plant morphology(植物形态学) . This work suggested that there were nine distinct species, not just four.

Results from this work were published in Planta Medica.



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1 helping 2rGzDc     
n.食物的一份&adj.帮助人的,辅助的
参考例句:
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
2 jumbled rpSzs2     
adj.混乱的;杂乱的
参考例句:
  • Books, shoes and clothes were jumbled together on the floor. 书、鞋子和衣服胡乱堆放在地板上。
  • The details of the accident were all jumbled together in his mind. 他把事故细节记得颠三倒四。
3 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。
4 criteria vafyC     
n.标准
参考例句:
  • The main criterion is value for money.主要的标准是钱要用得划算。
  • There are strict criteria for inclusion in the competition.参赛的标准很严格。
5 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
6 conserved d1dc02a3bfada72e10ece79fe3aa19af     
v.保护,保藏,保存( conserve的过去式和过去分词 )
参考例句:
  • He conserved his energy for the game. 他为比赛而养精蓄锐。 来自《简明英汉词典》
  • Under these conditions, the total mechanical energy remains constant, or is conserved. 在这种条件下,总机械能保持不变或机械能保存。 来自辞典例句
7 remarkable 8Vbx6     
adj.显著的,异常的,非凡的,值得注意的
参考例句:
  • She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
  • These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。
8 glaciers e815ddf266946d55974cdc5579cbd89b     
冰河,冰川( glacier的名词复数 )
参考例句:
  • Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
  • It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川,又有雨林和秀丽的山峰。 来自英语晨读30分(高一)
9 receded a802b3a97de1e72adfeda323ad5e0023     
v.逐渐远离( recede的过去式和过去分词 );向后倾斜;自原处后退或避开别人的注视;尤指问题
参考例句:
  • The floodwaters have now receded. 洪水现已消退。
  • The sound of the truck receded into the distance. 卡车的声音渐渐在远处消失了。
10 northward YHexe     
adv.向北;n.北方的地区
参考例句:
  • He pointed his boat northward.他将船驶向北方。
  • I would have a chance to head northward quickly.我就很快有机会去北方了。
11 blurred blurred     
v.(使)变模糊( blur的过去式和过去分词 );(使)难以区分;模模糊糊;迷离
参考例句:
  • She suffered from dizziness and blurred vision. 她饱受头晕目眩之苦。
  • Their lazy, blurred voices fell pleasantly on his ears. 他们那种慢吞吞、含糊不清的声音在他听起来却很悦耳。 来自《简明英汉词典》
12 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
13 aligned 165f93b99f87c219277d70d866425da6     
adj.对齐的,均衡的
参考例句:
  • Make sure the shelf is aligned with the top of the cupboard.务必使搁架与橱柜顶端对齐。
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