主题：【求助】【商榷】转基因技术看过来 -- lpf
家园 花谢，涨知识了
家园 试着理一下 问题提了几个，但是似乎说法并不准确，俺这个外行试着挑出真正需要解答的问题。
引文一：
食物来源外来基因与人体基因的重组是否会发生：如楼下所说，所有生物体都有基因，我们这辈子吃了无数外来基因下去，不还是好好的活着，而且基因还是很纯？基因治疗就是希望把外来有用基因导入人体发挥作用，但是这是需要专门的手段，而且导入的效果还是不佳。
细菌里检测到转入的基因DNA残留，这里需要明确的是食物带进来的DNA，还是被细菌复制的转入基因。如果是前者，那么和人摄入外来DNA没有什么差别。这里涉及到的问题是：植物中导入的基因会不会被肠道细菌所重组，或复制（类似质粒复制）？这个我想应该要看植物中导入基因的方式以及在后代中遗传的方式。具体不了解，不知道哪位明白人能解释一下。如果是后者，那么就是证明前面的问题有了肯定的回答，但是从文章来看，似乎没说是这么回事。
引文二：
需要解释的问题是：转入的基因在植物之间的自由传递会实现吗？同种之间（玉米转玉米）和异种之间（玉米转土豆）？
引文三：
口服转病毒基因的植物来产生抗体，这个太虚了。病毒的致病性这个问题好解决，去掉一些功能编码区就可以了。但是由植物来合成的病毒蛋白质会和人的细胞合成出来的一样吗？这个似乎有点扯了。不过咱们也比较孤陋寡闻，又不肯花时间查资料，就在这偷懒请教大牛了。
- 复 试着理一下
家园 我觉得能在植物里表达的DNA多半不能在细菌或者人里表达 启动子不一样，尾巴也不一样，应该就自动沉默了。
如果运气超级好的话，cDNA序列插到细菌基因组启动子后面，那还有戏。不过如果设计的时候在ORF里加几个内含子，这个问题也解决了。
人细胞的话，外源DNA自动进入细胞，进而再进入细胞核，进而再完整插入基因组，还没被沉默掉，这个可能性本身就很低。人细胞毕竟跟细菌不同，防御机制复杂多了。就算进去了，还要面对着跟在细菌里一样的困难：人细胞里基因表达的机制跟植物大不相同，进去以后多半不能正常转录。
家园 是啊 我想在植物中采用的转基因技术，应该考虑过这个问题，可以使用的技术应该很多，比如使用的载体等应该是有植物特异性的，在序列里面插入一些只有植物才可以执行的特殊片段等等。
我想既然人类已经摄入了那么多植物、动物、细菌和病毒的基因，目前仍然维持着自己的基因，那么转基因食物导致的基因重组，这个风险基本可以排除。
我觉得目前应该担心的还是新蛋白质的过敏问题。
家园 有几处讨论一下 2002 年英国进行了转基因食品 DNA 的人体残留试验。有 7 名做过切除大肠组织手术的志愿者，吃了用转基因大豆做的汉堡包之后，在他们的小肠肠道细菌里面检测到了转入的基因 DNA 残留这个测试很有趣，你说要是切除了小肠的人，在大肠测试DNA残留会不会更合适？毕竟小肠在大肠前面，切除大肠对小肠里面的内容有啥影响？
既然作者在这种地方都会犯错，别处有必要更多打几个问号
在收获大豆的时候，把转基因的药物玉米也收在了一起，整个大豆就都被污染了。这个地方作者开始是打算说：
我们可以看看国外的例子，其中玉米当年经常被转基因支持者称为花粉重，根本不可能散播出去的典范。大家都以为他打算说的是玉米基因污染了大豆基因，结果却是玉米倒入了大豆袋子，结果污染了大豆！！
疫苗那段真没看懂，前面讲了一大段转基因协助产生疫苗预防乙肝、艾滋病的好，突然来一句
很好，这种技术改让植物产出带有活性的病毒就成，跟你平时感染乙肝没啥区别，譬如口腔黏膜有破损，那么病毒将更好进入。另外如果这种病毒序列成功逃逸到其他植物，也可以造成灾难。我估摸着，前面是抄的可能性挺大，后面这句才是作者写的，
废话，啥技术落恐怖分子手里也很危险，“也可以造成灾难”，恐怖分子会开飞机撞大楼呢，全世界飞机都停飞了？
家园 逻辑太混乱了 一看就是烧糊涂的人写的。
原因楼下两位都说了。
家园 这个是新闻吗，随便找几篇文章 一篇关于转基因食品可能危害的综合文章
http://www.twnside.org.sg/title/maew-cn.htm
关于转基因作物可以使小鼠中毒的论文
http://www.actionbioscience.org/biotech/pusztai.html
转一种病毒基因的土豆和烟草里出现了该病毒的特异性蛋白，在强行喂
转基因烟叶和土豆后，小鼠体内出现了相关抗体。
Expression of Norwalk virus capsid protein in transgenic tobacco and potato and its oral immunogenicity in mice
1. H S Mason,
2. J M Ball,
3. J J Shi,
4. X Jiang,
5. M K Estes, and
6. C J Arntzen
+ Author Affiliations
1.
Plant Biotechnology Program, Albert Alkek Institute of Biosciences and Technology, Texas A & M University, Houston, 77030-3303, USA.
Abstract
Alternatives to cell culture systems for production of recombinant proteins could make very safe vaccines at a lower cost. We have used genetically engineered plants for expression of candidate vaccine antigens with the goal of using the edible plant organs for economical delivery of oral vaccines. Transgenic tobacco and potato plants were created that express the capsid protein of Norwalk virus, a calicivirus that causes epidemic acute gastroenteritis in humans. The capsid protein could be extracted from tobacco leaves in the form of 38-nm Norwalk virus-like particles. Recombinant Norwalk virus-like particle (rNV) was previously recovered when the same gene was expressed in recombinant baculovirus-infected insect cells. The capsid protein expressed in tobacco leaves and potato tubers cosedimented in sucrose gradients with insect cell-derived rNV and appeared identical to insect cell-derived rNV on immunoblots of SDS/polyacrylamide gels. The plant-expressed rNV was orally immunogenic in mice. Extracts of tobacco leaf expressing rNV were given to CD1 mice by gavage, and the treated mice developed both serum IgG and secretory IgA specific for rNV. Furthermore, when potato tubers expressing rNV were fed directly to mice, they developed serum IgG specific for rNV. These results indicate the potential usefulness of plants for production and delivery of edible vaccines. This is an appropriate technology for developing countries where vaccines are urgently needed.
人体系统能够消化吸收外来物质？哪也得看是什么外来物质才行，人类的食谱很有限，连自然的动植物里也处处是毒性蛋白质，甚至毒性氨基酸。
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凝集素 在豆类及一些豆状种籽（如蓖麻）中含有一种能使红血球细胞凝集的蛋白质，称为植物红血球凝集素，简称凝集素。已知凝集素有很多种类，其中大部分是糖蛋白，含糖量约4%～10%，其分子多由2或4个亚基组成，并含有二价金属离子。含凝集素的食物生食或烹调不足时会引起食者恶心、呕吐等症状，严重者甚至死亡。所有凝集素在湿热处理时均被破坏，在干热处理时则不被破坏。可采取加热处理、热水抽提等措施去毒。（1）大豆凝集素 大豆凝集素是一种糖蛋白，相对分子质量为110 000，糖类占5%，主要成分是甘露糖和N-乙酰葡萄糖胺。实验证明，吃生大豆的动物比吃熟大豆的动物需要更多的维生素、矿物质以及其他营养素，其原因还不清楚，但已发现它与肠道吸收的能力有关。大豆凝集素在常压下蒸汽处理1 h，或高压蒸汽处理15 min，可以使其失活。
(2)菜豆属豆类凝集素 菜豆属中已发现有凝集素的有菜豆、绿豆、芸豆等。有不少因生吃此类食物或烹调不充分而中毒的报道。用高压蒸汽处理15 min，可以使菜豆凝集素完全失活。
其他豆类如扁豆、蚕豆等也有类似毒性。
（3）蓖麻毒蛋白 蓖麻子不是食用种籽，但人、畜有生食蓖麻籽或油的，轻者中毒呕吐、腹泻，重则死亡。蓖麻中的毒素成分是蓖麻毒蛋白，毒性极大。在小白鼠的毒理实验中发现毒性比豆类凝集素要大1 000倍。用蒸汽加热处理可以去毒。
2．消化酶抑制剂 消化酶抑制剂也称蛋白酶抑制剂，常存在于豆类、谷类、马铃薯等食物中，比较重要的有胰蛋白酶抑制剂和淀粉酶抑制剂两类，它们都是蛋白质类物质。
（1）胰蛋白酶抑制剂 存在于大豆等豆类及马铃薯块茎食物中，分布极广。它可以与胰蛋白酶或胰凝乳蛋白酶给合，从而抑制了酶水解蛋白质的活性，使胃肠消化蛋白质的能力下降。由于胰蛋白酶受到抑制，使胰脏大量地制造胰蛋白酶，造成胰脏肿大，严重影响健康。
（2）淀粉酶抑制剂 在小麦、菜豆、芋头、未成熟的香蕉和芒果等食品中含有这种类型的酶抑制剂。可以使淀粉酶的活性钝化，影响淀粉的消化，从而引起消化不良等症状。
热处理也可有效消除蛋白酶抑制剂的作用。为破坏大豆中的蛋白酶抑制剂，通常采用高压蒸汽处理或浸泡后常压蒸煮的办法，或是微生物发酵的方法。相比之下，薯类和谷类中的蛋白酶抑制剂对热较为敏感，一般烹调条件均可使其失活。
3．毒肽 一些真菌中含有剧毒肽类，误食后可造成严重的后果。最典型的毒肽是存在于毒蕈中的鹅膏菌毒素和鬼笔菌毒素。鹅膏菌毒素是环辛肽，鬼笔菌毒素是环庚肽。这两种毒肽的毒性机制基本相同，都是作用于肝脏。鹅膏菌毒素的毒性大于鬼笔菌毒素。1个质量约50 g的毒蕈所含的毒素足以杀死一个成年人。误食毒蕈数小时后即可出现中毒症状，初期出现恶心，呕吐、腹泻和腹痛等胃肠炎症状，后期则是严重的肝、肾损伤。一般中毒后3～5 d死亡。
4．有毒氨基酸及其衍生物
（1）山黎豆毒素 山黎豆毒素主要有两类：一类是致神经麻痹的氨基酸毒素，有a，g-二氨基丁酸、g-N-草酰基-a，g-二氨基丁酸和b-N-a，b-二氨基丙酸；另一类是致骨骼畸形的氨基酸衍生物毒素，如b-N-（g-谷氨酰）-氨基丙腈、g-甲基-L-谷氨酸，g-羟基戊氨酸及山黎豆氨酸等。
人的典型山黎豆中毒症状是肌肉无力，不可逆的腿脚麻痹，甚至死亡。这种病常由于大量摄食山黎豆而爆发性地发生。
（2）b-氰基丙氨酸 存在于蚕豆中，是一种神经毒素，能引起与山黎豆中毒相同的症状。
（3）刀豆氨酸 是存在于刀豆属中的一种精氨酸同系物，在许多植物体内是抗精氨酸代谢物。焙炒或煮沸15～45 min可破坏大部分刀豆氨酸。
（4）L-3,4-二羟基苯丙氨酸（L-DOPA）。L-DOPA广泛存在于植物中，但蚕豆的豆荚中含量丰富，以游离态或b-糖苷态存在，是蚕豆病的主要病因。症状是急性溶血性贫血症，食后5～24 h发病，急性发作期可长达24～48 h，然后自愈。蚕豆病的发生多数是由于摄食过多的毒蚕豆（无论煮熟、去皮与否）所致。但L-DOPA也是一种药物，能治震颤性麻痹等症。
Hazards of Transgenic Plants Containing the Cauliflower Mosaic Viral Promoter
Authors’ reply to critiques of "The Cauliflower Mosaic Viral Promoter – a Recipe for Disaster?"
Microbial Ecology in Health and Disease
An electronic version of the full report can be downloaded from the ISIS online store. Download Now
Mae-Wan Ho and Angela Ryan Institute of Science in Society and Biology Department, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
Joe Cummins Department of Plant Sciences, University of Western Ontario, Ontario, Canada
(We are ignoring the comments of P. Christou, as they bear little relationship to the actual article that we submitted, and was published in your Journal. Our remarks are directed to the critiques from Hull, R., Covey, S.N. and Dale, P. of the John Innes Centre, and from Oliver Rautenberg of Biolinx.)
We reviewed and synthesized existing findings to predict potential hazards
As Rautenberg (1) rightly points out, our paper (2) was not drawn from research work that we have done ourselves, rather it was written to review and synthesize the scientific literature on and around the CaMV 35S promoter. This is a legitimate and important part of scientific activity, as science does not consist of isolated facts which bear no relationship to one another. It is precisely the web of mutual interrelationships of the findings that constitute science. More importantly, this maps out the universe of possibilities both for further research and for predicting potential hazards in risk assessment. Our critics disagree with the implications we draw from the scientific findings, and especially with our conclusions and recommendation.
To recapitulate, we pointed out that the CaMV 35S promoter is promiscuous in function, and works efficiently in all plants, as well as green algae, yeast and E. coli. It has a modular structure, with parts common to, and interchangeable with promoters of other plant and animal viruses. It also has a recombination hotspot, flanked by multiple motifs involved in recombination, and is similar to other recombination hotspots including the borders of the Agrobacterium T DNA vector most frequently used in making transgenic plants. The suspected mechanism of recombination – double-stranded DNA break-repair - requires little or no DNA sequence homologies. Finally, recombination between viral transgenes and infecting viruses has been demonstrated in the laboratory.
Transgenic constructs are already well-known to be unstable, and the existence of a recombination hotspot will exacerbate the problem. Consequently, transgenic constructs containing the CaMV promoter may be more prone to horizontal gene transfer and recombination than nontransgenic DNA. The
potential hazards include genome rearrangement, insertion mutagenesis, insertion carcinogenesis, the reactivation of dormant viruses and generation of new viruses (reviewed in refs. 3 and 4). These considerations are especially relevant in the light of recent findings that certain transgenic potatoes - containing the CaMV 35S promoter and transformed with Agrobacterium T-DNA - may be unsafe for young rats, and that a significant part of the effects may be due to "the construct or the genetic transformation (or both)" (5). Consequently, we called for all transgenic crops and products containing the CaMV promoter to be withdrawn and banned, which is in accordance with the precautionary principle as well as sound science.Hazards of Transgenic Plants Containing the Cauliflower Mosaic Viral Promoter
Authors’ reply to critiques of "The Cauliflower Mosaic Viral Promoter – a Recipe for Disaster?"
Microbial Ecology in Health and Disease
An electronic version of the full report can be downloaded from the ISIS online store. Download Now
Mae-Wan Ho and Angela Ryan Institute of Science in Society and Biology Department, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
Joe Cummins Department of Plant Sciences, University of Western Ontario, Ontario, Canada
(We are ignoring the comments of P. Christou, as they bear little relationship to the actual article that we submitted, and was published in your Journal. Our remarks are directed to the critiques from Hull, R., Covey, S.N. and Dale, P. of the John Innes Centre, and from Oliver Rautenberg of Biolinx.)
We reviewed and synthesized existing findings to predict potential hazards
As Rautenberg (1) rightly points out, our paper (2) was not drawn from research work that we have done ourselves, rather it was written to review and synthesize the scientific literature on and around the CaMV 35S promoter. This is a legitimate and important part of scientific activity, as science does not consist of isolated facts which bear no relationship to one another. It is precisely the web of mutual interrelationships of the findings that constitute science. More importantly, this maps out the universe of possibilities both for further research and for predicting potential hazards in risk assessment. Our critics disagree with the implications we draw from the scientific findings, and especially with our conclusions and recommendation.
To recapitulate, we pointed out that the CaMV 35S promoter is promiscuous in function, and works efficiently in all plants, as well as green algae, yeast and E. coli. It has a modular structure, with parts common to, and interchangeable with promoters of other plant and animal viruses. It also has a recombination hotspot, flanked by multiple motifs involved in recombination, and is similar to other recombination hotspots including the borders of the Agrobacterium T DNA vector most frequently used in making transgenic plants. The suspected mechanism of recombination – double-stranded DNA break-repair - requires little or no DNA sequence homologies. Finally, recombination between viral transgenes and infecting viruses has been demonstrated in the laboratory.
Transgenic constructs are already well-known to be unstable, and the existence of a recombination hotspot will exacerbate the problem. Consequently, transgenic constructs containing the CaMV promoter may be more prone to horizontal gene transfer and recombination than nontransgenic DNA. The
potential hazards include genome rearrangement, insertion mutagenesis, insertion carcinogenesis, the reactivation of dormant viruses and generation of new viruses (reviewed in refs. 3 and 4). These considerations are especially relevant in the light of recent findings that certain transgenic potatoes - containing the CaMV 35S promoter and transformed with Agrobacterium T-DNA - may be unsafe for young rats, and that a significant part of the effects may be due to "the construct or the genetic transformation (or both)" (5). Consequently, we called for all transgenic crops and products containing the CaMV promoter to be withdrawn and banned, which is in accordance with the precautionary principle as well as sound science.
Hazards of Transgenic Plants Containing the Cauliflower Mosaic Viral Promoter
Authors’ reply to critiques of "The Cauliflower Mosaic Viral Promoter – a Recipe for Disaster?"
Microbial Ecology in Health and Disease
An electronic version of the full report can be downloaded from the ISIS online store. Download Now
Mae-Wan Ho and Angela Ryan Institute of Science in Society and Biology Department, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
Joe Cummins Department of Plant Sciences, University of Western Ontario, Ontario, Canada
(We are ignoring the comments of P. Christou, as they bear little relationship to the actual article that we submitted, and was published in your Journal. Our remarks are directed to the critiques from Hull, R., Covey, S.N. and Dale, P. of the John Innes Centre, and from Oliver Rautenberg of Biolinx.)
We reviewed and synthesized existing findings to predict potential hazards
As Rautenberg (1) rightly points out, our paper (2) was not drawn from research work that we have done ourselves, rather it was written to review and synthesize the scientific literature on and around the CaMV 35S promoter. This is a legitimate and important part of scientific activity, as science does not consist of isolated facts which bear no relationship to one another. It is precisely the web of mutual interrelationships of the findings that constitute science. More importantly, this maps out the universe of possibilities both for further research and for predicting potential hazards in risk assessment. Our critics disagree with the implications we draw from the scientific findings, and especially with our conclusions and recommendation.
To recapitulate, we pointed out that the CaMV 35S promoter is promiscuous in function, and works efficiently in all plants, as well as green algae, yeast and E. coli. It has a modular structure, with parts common to, and interchangeable with promoters of other plant and animal viruses. It also has a recombination hotspot, flanked by multiple motifs involved in recombination, and is similar to other recombination hotspots including the borders of the Agrobacterium T DNA vector most frequently used in making transgenic plants. The suspected mechanism of recombination – double-stranded DNA break-repair - requires little or no DNA sequence homologies. Finally, recombination between viral transgenes and infecting viruses has been demonstrated in the laboratory.
Transgenic constructs are already well-known to be unstable, and the existence of a recombination hotspot will exacerbate the problem. Consequently, transgenic constructs containing the CaMV promoter may be more prone to horizontal gene transfer and recombination than nontransgenic DNA. The
potential hazards include genome rearrangement, insertion mutagenesis, insertion carcinogenesis, the reactivation of dormant viruses and generation of new viruses (reviewed in refs. 3 and 4). These considerations are especially relevant in the light of recent findings that certain transgenic potatoes - containing the CaMV 35S promoter and transformed with Agrobacterium T-DNA - may be unsafe for young rats, and that a significant part of the effects may be due to "the construct or the genetic transformation (or both)" (5). Consequently, we called for all transgenic crops and products containing the CaMV promoter to be withdrawn and banned, which is in accordance with the precautionary principle as well as sound science.
动物病毒dna放到植物dna里能不能产生动物病毒，估计没人做这种试验吧...
总之，他说的事情理论上是有可能的，实际会不会发生就不晓得了。
家园 说这么多，其实还是心里没底。 只要简单想想就知道了，任何生物都要摄入食物，并将其转换成自己身体的一部分，如果没有可靠的将食物DNA分离并转换成自己基因的能力，这个物种岂不是只能以自己为食？
基因的突变在任何生物身上都会发生，无论是否食用人类创造的转基因食物。
家园 基因不是转了才有，任何生物体内都有大量的基因。 我们吃的食物中除了水和一些无机添加剂以外，都有基因。如果吃了基因就会转入人体，那么中国人早就变成水稻了。
家园 开玩笑了 吃什么存什么当然是无稽之谈。
关键是我以前认为，食物到了人体会被消化吸收，不论蛋白质也好，DNA也罢，都会被还原成简单化合物例如氨基酸，核酸等等。但是，他举出DNA残留的例子，这个就很吓人了