主题：【原创】方舟子与转基因的安全 -- 花大熊
就拿西红柿来说好了，就是哥伦布时代就流传至今的品种，你敢说对它所含的所有物质，及所有这些物质进入人体后引发的所有连锁反应，全部了解的一清二楚了？
看来，任何“急速引入美洲新作物”都是对亚欧世界岛几十亿人民的健康和未来极其不负责任的行为
华尔街日报报道， 美国大量种植BT转基因玉米的爱荷华州发现抗BT的玉米害虫. 有机农业用BT菌做杀虫剂用了几十年没有催出抗BT的害虫， 转基因用了几年就弄出来了。 其实，这是不少农业生态学家早就预警很有可能发生的。
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http://online.wsj.com/article/SB10001424053111904009304576532742267732046.html
Monsanto Corn Plant Losing Bug Resistance
By SCOTT KILMAN
Widely grown corn plants that Monsanto Co. genetically modified to thwart a voracious bug are falling prey to that very pest in a few Iowa fields, the first time a major Midwest scourge has developed resistance to a genetically modified crop.
The discovery raises concerns that the way some farmers are using biotech crops could spawn superbugs.
Iowa State University entomologist Aaron Gassmann's discovery that western corn rootworms in four northeast Iowa fields have evolved to resist the natural pesticide made by Monsanto's corn plant could encourage some farmers to switch to insect-proof seeds sold by competitors of the St. Louis crop biotechnology giant, and to return to spraying harsher synthetic insecticides on their fields.
"These are isolated cases, and it isn't clear how widespread the problem will become," said Dr. Gassmann in an interview. "But it is an early warning that management practices need to change."
The finding adds fuel to the race among crop biotechnology rivals to locate the next generation of genes that can protect plants from insects. Scientists at Monsanto and Syngenta AG of Basel, Switzerland, are already researching how to use a medical breakthrough called RNA interference to, among other things, make crops deadly for insects to eat. If this works, a bug munching on such a plant could ingest genetic code that turns off one of its essential genes.
Monsanto said its rootworm-resistant corn seed lines are working as it expected "on more than 99% of the acres planted with this technology" and that it is too early to know what the Iowa State University study means for farmers.
The discovery comes amid a debate about whether the genetically modified crops that now saturate the Farm Belt are changing how some farmers operate in undesirable ways.
These insect-proof and herbicide-resistant crops make farming so much easier that many growers rely heavily on the technology, violating a basic tenet of pest management, which warns that using one method year after year gives more opportunity for pests to adapt.
Monsanto is already at the center of this issue because of its success since the 1990s marketing seeds that grow into crops that can survive exposure to its Roundup herbicide, a glyphosate-based chemical known for its ability to kill almost anything green.
These seeds made it so convenient for farmers to spray Roundup that many farmers stopped using other weedkillers. As a result, say many scientists, superweeds immune to Roundup have spread to millions of acres in more than 20 states in the South and Midwest.
Monsanto became the first company to sell rootworm-resistant biotech corn to farmers in 2003. The seed contains a gene from a common soil microorganism called Bacillus thuringiensis, or Bt, from which crop biotechnology has been used to mine several genes for making insecticidal proteins.
One of the genes Monsanto developed makes a crystalline protein called Cry3Bb1. It rips apart the gut of the rootworm but is harmless to mammals, birds and most beneficial insects. Competitors, which use other Bt genes to attack the rootworm, estimate that roughly one-third of the corn grown in the U.S. carries Monsanto's Cry3Bb1 gene.
Monsanto said it generated world-wide sales of $4.26 billion from corn seed and biotechnology traits, about 40% of its overall sales, in its last full year.
Until insecticide-producing corn plants arrived, Midwest farmers typically tried to keep pests like the corn borer and the rootworm in check by changing what they grew in a field each year, often rotating between corn and soybeans. That way, the offspring of corn-loving insects would starve the next year.
Some farmers began to plant corn in the same field year after year. The financial incentive to grow corn has increased in recent years in part because the ethanol-fuel industry's exploding appetite for corn has helped to lift prices to very profitable levels for growers.
According to Dr. Gassmann, the Iowa fields in which he found rootworms resistant to the Cry3Bb1 toxin had been producing Monsanto's Bt-expressing corn continuously for at least three years. Dr. Gassmann collected rootworm beetles from four Iowa cornfields with plant damage in 2009. Their larvae were then fed corn containing Monsanto's Cry3Bb1 toxin. They had a survival rate three times that of control larvae that ate the same corn.
Dr. Gassmann found that Monsanto's Bt toxin still had some lethal impact on the larvae from the problem Iowa fields, and that the bugs were still highly susceptible to a rootworm-resistant corn plant from a competitor that uses a different Bt toxin, called Cry34/35Ab1.
Scientists in other Farm Belt states are also looking for signs that Monsanto's Bt corn might be losing its effectiveness. Mike Gray, a University of Illinois entomologist, said he is studying rootworm beetles he collected in northwest Illinois earlier this month from fields where Monsanto's Bt-expressing corn had suffered extensive rootworm damage.
The government requires that farmers who plant the genetically modified corn take certain steps aimed at preventing insects from developing resistance. Farmers are told to create a refuge for the bugs by planting non-modified corn in part of their fields. The refuge, which can be as much as 20% of a farmer's field, is supposed to reduce the chances that two toxin-resistant bugs mate and pass along that trait to their offspring.
Dr. Gray said the confirmation of toxin-resistant rootworms in Iowa could force the U.S. Environmental Protection Agency to revisit its policy of allowing the size of these insect refuges to shrink to as little as 5% of a cornfield as crop biotechnology companies begin to sell seed for corn plants that can make two different rootworm-killing toxins.
Part of what has attracted some farmers to Monsanto's new SmartStax corn line is that it allows them to plant a smaller refuge. But one of the two anti-rootworm toxins in that variety is the Cry3Bb1 protein at the center of Dr. Gassmann's study.
The EPA said it is too early to comment on any implications arising from Dr. Gassmann's paper.
Write to Scott Kilman at [email protected]
666都能对付的了，虫子们还怕小小的BT蛋白?
充其量是时间长短的问题。
好在国家也不糊涂。
一个字，拖。
拖到美国白老鼠的数据足够了，俺们再说话。
没准也出个啥英雄，呵呵。
说不定是你哦
在你的教育下，我已经学会西西河式样的赌博方法。
就是在打任何赌之前一定要加上前缀，话说你这次咋改了，不高呼花大熊永远永远不敢如何如何啦？
真不习惯了。
我得承认，你在网络上蛮肯下力气的。
反正我认为转基因该做新资源食品的认证。俺也不是键盘卫生部，或者键盘农业部的。更不是市场部的。承蒙你这么看着咱。
先谢过啦。哈哈
反正你啥安全报告都拿不出来，对不？
你就认一条，不需要做了，对不？
俺也来把西西河式样的打赌，***永远永远不敢承认他拿不出安全报告的。
少了主语，谁拿不出呢？
猜中花谢哦！
PS：你也还算是谨慎滴，在了解基因奥秘前面加了个初步。算是初步从上帝的水平后退了一把。至于基因的奥秘，谁了解都是可能滴。俺再一次西西河式样的幽默一把，有些人永远永远都不会正面去了解滴。
回答你这个问题有些风险，因为是活在当下的人物。
试着说说吧，只能简单些了。
辐射育种，产生新的表型，也就产生新的性状，这个是没问题滴。
按照达尔文和孟德尔的推测，自然是属于新的基因型。
但是多基因调控的现象越来越多，很多传统意义上说的所谓新基因型，实际上只是相同基因的不同表型。
你说的矮杆，起码在不同的节段上是如此的。
这本书，作为本科教材，估计下一次修订，会要修改了。
我们对如何创造一个新的基因，目前近乎一无所知。
大部分集中在定位与调控方面。
斯坦福据说有个设计基因的计划。老实说，我猜还是挂羊头卖狗肉。
诱变这一块，我不是很擅长。是不是有全新的基因出现，没有仔细的了解。据我所知，大部分新发现的基因，还是来自自然界。
如果你有相关的实例，欢迎赐教
仅供参考
就是不转这个基因，人也早就不知不觉地吃过Bt。
我对你一开始的提问(或质问疑问,随便替换好了)如下
我敢打赌，楼主和他们的同道们，永远，永远，不会正面回答这个问题。
你的正面回答在哪呢?
莫非是这个?
请勿将悟空换成黑岛人。否则后果自负
还是这个?
我的原问是请你指出几种或者哪怕一种,能经得起你为转基因作物设定的上市安全检测标准的已有作物。这恐怕是小学生都能读懂的问题，很可惜，你要么拉扯到人身攻击上，要么就转进至上市安全检测标准本身及其合理性的辩护上。我请求的很简单或者说最简单的答案---符合你之安全要求的作物品种的名称在哪儿呢？似乎到目前为止，我的赌你（们）还是没敢来应，除非你的词典里“转进”已经等于“胜利”了。
你认为转基因该做新资源食品的认证，是你的观点，但据我所知，你这种观点没有在生物分类上（将转基因品种视为新的物种）得到科学界的支持，确切的说，是相关观点没有什么论文在严肃的科学刊物上得到过发表，以供科学界讨论。在这种情况下，我觉得你每次都还不忘用“键盘卫生部，或者键盘农业部”这种话来影射，实在是很精通猪悟能大师的绝招。
至于我为什么反对强制要求转基因作物必须接受药品上市的检测标准，以及我认为你如此要求的实际用心，在上楼中已经比较充分的阐述了。在此只需要再次指出——对食品，包括不同主粮的品种，安全标准应该是一致的，你在公然声称非转基因作物因为你“对其极有信心”就不必作相关检测，而转基因作物则必须（显然因为你“对其没有信心”），这种双重标准不仅是虚伪的，而且是可笑的。事实上，从以上多次公然的提倡双重标准，以及你从本楼一开始就有的那种“对转基因作物所有成份及进入人体后的所有后果”全都“尽在掌握”的要求，还有在遇到质疑后频繁的进行对人不对事的人身攻击的行径，我认为恰恰反映出你具有一定的自认绝对正确不容反对的“上帝倾向”。
本帖一共被 2 帖 引用 (帖内工具实现)
以及
具体到bt蛋白的例子，bt蛋白在细菌的基因组中所经受的检验（承受的选择），和它在水稻基因组中所经受的检验（选择），是两回事。前者的时间是很长的，而后者的时间是非常短的。你说的“人不知不觉地吃了bt蛋白”的情况属于前者。
补一句，不是人吃了无毒就是安全的。所谓安全性应当包括这种东西对人类赖以生存的农田生态系统的生态平衡影响有多大。苏云金杆菌在土壤中只是数十万中微生物之一，而水稻是农田生态系统的绝对优势物种。bt蛋白在水稻中表达和在苏云金杆菌中表达的生态影响完全不可同日而语。所以如果从bt蛋白可以被人的胃液降解推论出转基因水稻的安全性，我只能说这个安全性所经历的考验时间太短。
在我的字典里,他已经成为了学棍.
我不明白,他是依靠什么来生活的,难道是另有收入?
一种是从头创造一个新基因，所谓denovo的，另一种是基因复制乃至基因组复制后的重组。芝大的龙漫远就是做新基因的de novo起源的。03年他在nature review genetics上发了一篇综述把这个问题说得很详细了。
另外，寒武纪爆发这种事情涉及宏进化和微进化的不同机制。我也觉得，这个过程肯定不是一两个基因的变化造成的，而是某种基因组水平的整体改变。现在困难的是我们不知道这种改变（如果有的话）会在什么条件下发生。就像间断平衡假说所遭遇的困境一样，如果所有的种以上改变都已经发生过而所有的现在发生的变异都是种以内的变异，那么种以上的进化就是一种没有意义的完全是关于过去的演化。
我觉得，关键还是在基因组比较中找到宏进化发生的可能的蛛丝马迹。而现有的比较基因组方法，显然是不能完成这个任务的。。。
召集人联名写信给张启发怎么样？你参加不？
的确，目前诱变“新”基因都是把原有基因打断或者提前终止，破坏其原有功能导致了相关变化，我没有见到有诱变导致原来一个基因或无意义DNA片段产生了新的完全不相干功能的报道（理论上应该存在）。
但回到你们最初始的讨论话题，即诱变会不会导致食用突变后的水稻种子而产生某些对人体有负面影响，那是完全有可能的。诱变水稻籽粒中营养成分变化是相当大的，保不齐有什么诱变后的水稻里某种对人体有益氨基酸含量就降低了。
实际上水稻种子里含有植酸，而植酸易同铁、钙等金属离子或蛋白质结合排出体外，是多种动物的抗营养因子，因此是否可以理解为我们食用了上千年的水稻本身按照所谓“完全没有负面影响”的对转基因主粮的评价标准，本身就是不合格的？
玉米中的什么糖成分有楼上老兄说的作用。
引起味觉的天然单糖就那么十几种。这话的意思是说，有一种单糖（或者二糖等寡糖）可以进入能量代谢途径却不引起味觉反应。这倒是很有趣的东西。
这是什么糖？