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主题:【求助】【商榷】转基因技术看过来 -- lpf

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家园 【求助】【商榷】转基因技术看过来

河里前些日子关于转基因的问题科普过很多次,本来以为已经搞明白这个问题了,但是在百度看了一篇文章,发现很多认识又糊涂了。希望从事生物领域的大牛再科普一把,传道解惑也。

真正搞生物工程技术人士眼中的转基因 http://tieba.baidu.com/f?kz=892695555

五问转来的基因会不会与人类的基因产生重组而引发变异?

一转基因本身,即DNA,是否会与人类的基因组发生重组?

这个课题还没有确切答案,可能大家会在网上看到方舟子所说的DNA会被降解成核酸,没有危害,实际上这个说法也是用手法忽悠,即使最严肃的FDA和WHO也不敢贸然宣称人类的肠胃能降解100%的DNA,即使一个身体健康的人在大肠中也只能使得绝大部分DNA失活,还有前提是这个DNA是正常的DNA,这个正常的DNA的说法或许你们不好理解,我也不好举例,我们举个蛋白质的例子,继续来说疯牛病的罪魁祸首朊病毒,这种蛋白质通过特殊折叠的甚至结合金属离子,可以使肠胃束手无策,本来蛋白质应该被分解成氨基酸,但是对这种蛋白质无法分解,所以才有疯牛病传染到人身上,要是人肠胃都能分解蛋白质到氨基酸,哪还来什么疯牛病,DNA也是一样,人类的消化功能又不是万能的,目前我们说能使大部分DNA失活,是基于我们现在普通的情况下,普通的食物,至于特殊情况下,我们不知道,FDA和WHO目前的结论是没有先例,暂时大家都不知道就不知道吧,就当DNA失活。实际上,这两个组织至少还是承认起码有大概<0.1%DNA是不失活的,不过这些不失活的DNA结合到人体内很困难,要大量意外的条件。目前实验多是小范围的,这种意外比较难找,如果全世界都转基因了,估计这意外的概率大概会猛增。

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。由于在转基因的时候,是用抗生素做标记的。所以认为如果吃了含有这种标记基因的食物,可能使肠道细菌或者是口腔细菌产生对抗生素的一种抗性。对此也提出疑问。这个实验也遭到了诟病,反对者认为切除大肠组织的人毕竟是少数,无关痛痒。呵呵,切除组织的人是少数,但是肠胃消化功能不良的人却并不少见,谁知道肠胃功能不良碰上转基因会有什么后果呢?

作者这里提到的问题DNA能否全被消化失活和残留。以前印象里,人体消化系统能够吸收分解掉外来物转换为人体所需物质,但这里作者给出了反证,到底事实如何?

七问转基因的历史及发展如何?

最早的基因转移可以追溯到英国的细菌学家格里菲斯(Griffith)于1928年发现的肺炎双球菌的转化现象,简单的说有两种肺炎双球菌一种对白鼠有毒,一种没毒,把有毒的一种加热杀死后和无毒的一种菌混合后,无毒的可以接受有毒的菌体中的DNA从而使无毒的菌株转化为有毒的菌株,不过肺炎双球菌还是比较脆弱的,60度加热即可杀死,而且这些有毒的基因组可以被DNA酶所降解失活。这个现象被称为转化,也是生物学上一个非常重要的概念。也就是说同种之间一定条件下,同种微生物的基因可以相互转移。

之后人类开始发现另一种现象称为转导,他跟转化也有异曲同工之妙,只不过要用载体,其实就是转基因技术的雏形。

目前微生物上所用的转基因技术利用病毒以及酵母质粒(质粒也是DNA的一种,只是独立性的问题,换个名词)来作为媒介向其他生物中转基因

事实上,微生物及植物的基因重组,转移我们并没有完全搞清楚,甚至可以说还是一头雾水 。因此转基因从开始时,就提出了一个问题即:

基因漂移(或基因流gene flow)是指基因通过一定的媒介在同一物种的群体之间,甚至是不同物种之间进行移动的现象。基因漂移有两种方式,即基因的垂直漂移(vertical gene flow)和水平转移(horizontal gene transfer)

一般来说,同物种间基因的转来转去更为容易,所以把一些本来自然界中根本不会传到植物基因组的基因转入植物基因组,可能有使这些基因撒布到其他植物的风险,那么转入的基因如果被无限制传播,最终导致的结果是什么,不知道,包括可以查到的国内铁杆的转基因支持者复旦的风险评估,国外各个组的综述中最后能告诉你的一定是不知道。谁要宣称知道你可以推荐他去拿诺贝尔奖,而且是十个,一个哪够?

那他们宣称的安全是什么,很简单,把其他未知因素剔除,掩耳盗铃就行,如华中农大支持转基因水稻的理由就把水稻的基因漂移限定到只考虑亲种之间的传播,并且主要只考虑花粉介导传播一个途径(其实基因转移还有譬如无性器官介导,种子介导等等等),证明他们的田间管理,隔离带是怎么怎么有效,花粉不会散出去,向民众大吹特吹安全性,规矩是他定的,他当然爱说什么说什么。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。

著名的事件有:

美国的星联玉米, Star link 玉米事件。这种玉米是 1998 年美国环保局批准商业化生产,当时批准是用作动物性饲料,不是用于人食用,因为它对人体有过敏,可能产生皮疹、腹泻。但是在 2000 年,在市场上 30 多种玉米食品当中发现了这种玉米的成分,所以美国政府下令把所有的这种转基因玉米收回。另外,还有一个是美国的药用转基因玉米污染大豆的事件。一家公司它开发了一种给病人吃的药物玉米,而不是给普通的消费者吃的,是治病用的,也许对某种病,艾滋病或者什么病把这种转基因玉米当做一种药吃的。结果在上一年种了这种药物玉米的土地上没有根除。第二年接着种了大豆,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。于是美国政府下令把仓库里面混装有药用玉米的所有的大豆都销毁,总计有约 100 万蒲式耳。这个事件说明污染是很容易产生,尽管某些转基因的生物说的很明确,不是用于人的,或者说是用于动物的,用于药用的。但是它很容易污染,很容易造成食品的不安全,存在隐患。

另外如果肆意转基因,导致不育其实并不困难,这个倒不用特别说明。导致人类基因重组,可能危言耸听了点,但是我可以明确的说,技术上毫无困难。

举个最简单的例子,大家查查乙肝这个中国的常见病,一般又称HBV,乙肝的恶化情况之一就是HBV整合到人体基因组里,甚至有科学报道可以整合到干细胞上,并利用我们本身的DNA增殖而增殖。因此乙肝一直是令我国政府最头痛的病魔之一,非常难治,而这个病毒也有人用来产转基因,当然这个必须是失去毒性的病毒序列,查了下,也可以是完全的乙肝病毒序列,科学家一般是将之整合到植物基因中,让植物产出病毒,将其中的DNA灭活,外层蛋白质作为抗原,当疫苗,这样人吃了,可以不得病并且产生抗体,达到疫苗的作用。

据英国《新科学家》杂志2006年29日报道,俄罗斯西伯利亚植物生理学和生物化学研究所的科学家利用土壤农杆菌,将艾滋病病毒和乙肝病毒DNA片段合成物送入西红柿植株。经过这种方法处理的西红柿植株能制造这些病毒的蛋白质。

科学家给实验鼠喂食含这种转基因西红柿粉末的溶液后发现,实验鼠血液中产生了艾滋病病毒和乙肝病毒的高含量抗体。

更重要的是,科学家还在实验鼠器官黏膜表面发现了抗体。黏膜是艾滋病病毒等通过性接触进入体内的“大门”。

科学家说,如果用这种西红柿制造的疫苗同样对人体有效的话,将能够以片剂形式供人们服用。其优点是无需冷藏,无需注射,感染风险低,易于生产。

目前,抗艾滋病病毒的潜在疫苗有90多种,效果均不理想,而被证实有效的抗乙肝病毒疫苗目前价格比较昂贵。

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。

作者的例子,有反驳的意见吗?

关键词(Tags): #转基因通宝推:类反词典,
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 我来证明

我就是一株刚转基因变成的是能上网的中国籍水稻。

远离基因,珍爱生命。

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 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。

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 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 第一个例子有问题

转基因烟草和土豆会表达该基因编码的蛋白。小鼠吃了这种蛋白,可以产生相应的抗体,这很正常。我们的胃肠道遇到没有变性的、第一次遇到的蛋白质,也可能产生相应的抗体。

这和转入基因进入人体内会否和人体基因重组是2回事。

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,你说要是切除了肠的人,在肠测试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 那就理论上有过敏的可能对不对

谁说要基因重组了,卡卡

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。

家园 啊?哦。
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

家园 抗生素做标记!?

由于在转基因的时候,是用抗生素做标记的

这人似乎是想说 Immunostaining 吧?

连我这不是学生物的也不会翻译成抗生素标记

外链出处

家园 他说得倒是没错,不过确切的说,应该是抗-抗生素标记

做基因工程的时候,在转入的基因上,经常加个antibiotic-resistance marker。它本身也是个基因,一般就是个酶,可以降解抗生素,比如说抗青霉素基因,抗四环素基因啊什么的。然后往被转的生物上加点抗生素,没转上的就抑制或者杀死了,带目标基因能降解抗生素,于是死不了,就被选择出来了,这是个很方便的办法。

说两个抗比较麻烦,所以一般就简单的叫它抗生素标记。我以下也这么叫了。

基础研究不大考虑环境影响,所以抗生素标记用得多。大部分搞生物的都是在搞基础研究,或者至少一开始是在基础研究的实验室训练出来的,所以这个学生物的人想到这个问题很正常。

对于应用研究来说,标记方法应该是首要的考虑之一。基因的水平转移是个已经被知道大概半个世纪的事情。如果连这都不考虑的话,那是太业余了。

我不知道目前商业化的转基因作物用的是什么标记。不过除了抗生素标记,还有很多其他的办法来标记基因。其实除了被转的基因本身,不再加入任何额外标记也是可行的,比如你说的免疫方法就能直接检测转入的基因产物,或者用杂交的办法检测被转的基因序列本身(跟免疫办法想法差不多,就是用DNA探针直接检测DNA而已)。很多方法对人和环境都是没啥影响的。我个人觉得这不应该是个大问题,应该早被解决了。

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。

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