研究昆虫控制的文章Athenix and Monsanto Announce Collaboration on Research for Insect ControlRESEARCH TRIANGLE PARK, . and ST. LOUIS, June 20 /PRNewswire-FirstCall/ -- Athenix Corp. and Monsanto Company today announced they have entered into a three-year research collaboration for insect control on a key class of insects that affects a number of Monsanto's major crops of interest. Financial terms of the agreement were not disclosed. "We are pleased to work with the market leader in crop genetics to bring our technical capabilities to commercialization," said Mike Koziel, chief executive officer for Athenix. "Working with Monsanto to discover novel genes for controlling insect pests increases options for farmers and allows Athenix to demonstrate the power of its integrated discovery platforms for new biotech traits," said Nick Duck, vice president of research at Athenix. Athenix will apply its expertise in microbial screening and genomics to facilitate gene discovery intended to help protect crops such as cotton, soybeans and corn against a common class of insects known as Hemipterans. Hemipteran insects include Lygus, a pest of cotton, and stinkbug, a pest of soybean. "This collaboration will work to offer an essential benefit to our farmer customers by providing insect protection in crops such as corn, cotton and soybeans against the piercing and sucking insects. Insect tolerant crops allow growers to spray less pesticide, making their operations more efficient and at the same time stewarding the environment," said Robert T. Fraley, ., Monsanto executive vice president and chief technology officer. "We're excited to collaborate with Athenix to help broaden grower's options for insect control." About Athenix: Athenix is a leading biotechnology company that develops novel products and technologies for agricultural and industrial applications, including biofuels and bioconversions. Athenix has established an outstanding intellectual property portfolio and market access ability around enhanced plants, microbes, genes, enzymes, and processes with emphasis on two major markets: 1) novel agricultural traits for growers such as insect resistance, nematode resistance, herbicide tolerance, and their use for the crop production industry; and 2) the discovery of genes and proteins for use in the sustainable chemical industry with a focus on biofuels like ethanol and other natural control of locusts New weapons for old enemiesDuring the 1988 desert locust plague, swarms crossed the Atlantic from Mauritania to the Caribbean, flying 5 000 kilometres in 10 were stumped because migrating swarms normally come down to rest every night. But locusts can’t swim, so how could it be? It turned out that the swarms were coming down at sea – on any ships they could find, but also in the water itself. The first ones in all drowned but their corpses made rafts for the other ones to rest on. Since the dawn of agriculture more than 10 000 years ago mankind has had to deal with a resourceful and fearless enemy, Schistocerca gregaria, the desert locust. Normally loners, every so often these natives of the deserts from West Africa to India turn into vast, voracious swarms that leave hunger and poverty behind them wherever they go. Throughout history, farmers and governments have made attempts to repel the bands and swarms of locusts by collecting insects, creating noise, making smoke and burying and burning the insects. But all of this had little effect. With swarms sometimes extending for hundreds of kilometres, and containing billions of individuals, they conquered by sheer force of numbers. Health concernsIt has long puzzled humans where these animals came from and where they survived. Only in the mid-20th century was it realized that the light brown solitary desert-dwelling insect was the same species as the red and yellow locusts of the plagues. Only when its biology was understood and chemical pesticides and aerial spraying became available a few decades ago, could efforts be made to control the insect. But large-scale pesticide use also raised real concerns for human health and the environment. On the seventh-floor Emergency Centre for Locust Operations (ECLO) at FAO Headquarters in Rome, Keith Cressman, FAO's locust forecaster, checks current environmental conditions and locust population data from the three computer screens on his desk. The last big locust upsurge ended early in 2005 and the current alert level is green or calm. The experts at FAO’s ECLO are readying to fight the next round in the age-old battle against locusts – wherever and whenever that may be. “The next time,” says Cressman, “we’ll fight with new tools”. New bio-control agents Recent advances in biological control research, coupled with improved surveillance and intelligence, could make a big difference when the next round in the battle is fought. Such products could make it possible to sharply reduce the amount of chemical pesticides used. One promising avenue is research currently under way at the International Centre for Insect Physiology and Ecology (ICIPE) in Nairobi. An ICIPE team headed by a Zanzibar-born chemical ecologist, Ahmed Hassanali, has identified and synthesized a specific locust pheromone, or chemical signal, that can be used against young locusts with devastating , or PAN for short, normally governs swarming behaviour in adult males who also use it to warn other males to leave them in peace while they mate. But, Hassanali found it has startlingly different results on juvenile wingless locusts, known as hoppers. Hopper bandsJust as adult locusts form swarms, hoppers will, given the right conditions, stop behaving as individuals and line up in marauding bands up to 5 kilometres wide. They are only slightly less voracious than adults, who eat their own weight of food every day. In three separate field trials – the most recent in Sudan last year – Hassanali’s team showed that even minute doses of PAN could stop hopper bands dead in their tracks and make them break caused the insects to resume solitary behaviour. Confused and disoriented, some lost their appetite altogether, while others turned cannibal and ate one other. Any survivors were easy prey for predators. What makes PAN particularly attractive is that the dose needed is only a fraction – typically less than 10 millilitres per hectare – of the quantities of chemical or biological pesticides. This translates into substantially lower costs – 50 cents per hectare as opposed to US$12 for chemical pesticides and $15-20 for other bio-control is clearly a major consideration in the countries in the front line – many of them among the world’s poorest. Green Muscle A different, but also highly effective biological approach is Green Muscle ®, a bio-pesticide developed by the International Institute for Tropical Agriculture’s biological control centre in Cotonou, Benin, and manufactured in South Africa. Green Muscle ® contains spores of the naturally occurring fungus Metarhizium anisopliae var. acridum, which germinate on the skin of locusts and penetrate through their exoskeletons. The fungus then destroys the locust's tissues from the inside. This is definitely not good news for locusts, but the fungus has no effect on other life forms. A product similar to Green Muscle ® is already successfully used in Australia, but the latter's introduction in Africa and Asia is being slowed by several factors. These include a need for further large-scale trials, official approval of the product in several countries, and a relatively short shelf-life in its normal ready-to-spray liquid form. One drawback is that it takes days to kill the locusts. It is also relatively expensive and large-scale production would need to be organized. A solution would be to store the product in powder form and dilute it just before use. Hassanali’s team has also shown that, if used in combination with a small amount of PAN, only a quarter of the normal dose of Green Muscle ® is Growth RegulatorsAlso being readied for the modern locust fighter’s armoury is a class of products known as Insect Growth Regulators, or IGRs, which influence the ability of hoppers to moult and grow properly. They have no direct toxic effects on vertebrates. IGRs are effective for several weeks after application and can be used in so-called barrier treatments. In this method only narrow swathes of the product are applied, perpendicular to the direction of the marching hopper bands. Only 10 percent of the amount used in blanket treatment is needed. After marching over one or two barriers the hoppers absorb enough product to die while moulting. As with PAN and Green Muscle ®, however, IGRs need to be aimed at locusts at an early stage in their lives, before they take to the air. That, in turn, requires an advanced level of surveillance and intelligence-gathering to make sure that any locust concentrations are nipped in the bud. eLocust2Although back at ECLO Keith Cressman has satellites, computers and mathematical models at his disposal, the weak link in the chain has been the time it takes to get good information from the mobile ground teams whose job it is to keep tabs on locust populations have to work in some of the world’s remotest, hottest and sometimes (for environmental and security reasons) most hostile places. A week or more might go by before a report from, say, the central Sahara, reached Cressman’s desk. By that time the locusts – “They don’t need visas,” he says – would quite likely have moved to another country or continent altogether. This will soon change however. Field teams are now being issued with special hand-held devices to record vital locust and environmental data and relay them back to their own headquarters and on to Rome in real time. Developed by the French Space Agency CNES, the eLocust2 device is able to bounce the information off communications satellites and have the data arrive in the National Locust Control Centre in the affected country a few minutes later, from where they are passed on to Cressman for analysis. In case of unusually heavy hopper concentrations, immediate action can be taken to make sure that the locusts never grow old enough to swarm. Back to the fieldWriting in Science magazine, locust expert Martin Enserink gave the following graphic description of a locust population gone out of control:“On a beautiful November morning (in Morocco) it’s clear, even from afar, that something’s terribly wrong with the trees around this tiny village. They are covered with a pinkish-red gloss, as if their leaves were changing colour... "As you get closer, the hue becomes a wriggling mass; a giant cap of insects on every tree, devouring the tiny leaves. Get closer still and you’ll hear a soft drizzle: the steady stream of locust droppings falling to the ground.” Such nightmare visions, and locust plagues with them, may one day be a thing of the past.
catchinginsects(现在进行时)catchinsects(一般形态)
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呵呵。这个提问太哪个了。不好回答。
果蝇生活史果蝇科(Drosophilidae)果蝇属(Drosophila)昆虫。约1,000种。广泛用作遗传和演化的室内外研究材料,尤其是黄果蝇(D. melanogaster)易於培育。其生活史短,在室温下不到两周。 关於果蝇的遗传资料收集得比任何动物都多。用果蝇的染色体,尤其是成熟幼虫唾腺中最大的染色体,研究遗传特性和基因作用的基础。对果蝇在自然界的生物学了解得还不够。有些种生活以腐烂水果上。有些种则在真菌或肉质的花中生活。 [编辑本段]外观特征 黄果蝇(Drosophila melanogaster)体型较小,身长3~4mm。近似种鉴定困难,主要特征是具有硕大的红色复眼。 雌性体长毫米, 雄性较之还要小。雄性有深色后肢,可以此来与雌性作区别。 [编辑本段]分布范围果蝇类昆虫与人类一样分布于全世界,并且在人类的居室内过冬。由於体型小,很容易穿过砂窗,因此居家环境内也很常见。 [编辑本段]生活环境有些种生活以腐烂水果上。有些种则在真菌或肉质的花中生活。 在垃圾筒边或久置的水果上,只要发现许多红眼的小蝇,即是果蝇;果蝇类幼虫习惯孳生於垃圾堆或腐果上。 [编辑本段]黑腹果蝇 黑腹果蝇在1830年首次被描述。而它第一次被用作试验研究对象则要到1901年,试验者是动物学家和遗传学家威廉·恩斯特·卡斯特。他通过对果蝇的种系研究,设法了解多代近亲繁殖的结果和取自其中某一代进行杂交所出现的现象。1910年,汤玛斯·亨特·摩尔根开始在实验室内培育果蝇并对它进行系统的研究。之后,很多遗传学家就开始用果蝇作研究,并且取得了很多遗传学方面的知识,包括这种蝇类基因组里的基因在染色体上的分布。 雌蝇可以一次产下400个毫米大小的卵,它们有绒毛膜和一层卵黄膜包被。其发育速度受环境温度影响。在25℃环境下,22小时后幼虫就会破壳而出, 并且立刻觅食。因为母体会将它们放在腐烂的水果上或其他发酵的有机物上,所以它们的首要食物来源是使水果腐烂的微生物,如酵母和细菌,其次是含糖的水果。幼虫24小时后就会第一次蜕皮,并且不断生长,以到达第二幼体发育期。经过三个幼虫发育阶段和四天的蛹期,在25℃下过一天,就会发育为成虫。 [编辑本段]科学研究转基因果蝇转基因果蝇出世:可用激光照射遥控 遥控不再是电子产品的专利,科学家新培育出一种转基因果蝇,可以用激光照射来遥控它们的行为,让懒散的果蝇活动起来,开始爬行、跳跃或飞走。 有关论文发表在最新一期的《细胞》杂志上。虽然遥控这种果蝇还不能像开遥控汽车那样方便,但有关方法对研究动物的神经和行为有着重要意义。 以前,科学家在研究动物行为的神经基础时,一般用电极刺激神经等方法。但这些方法是侵入性的,可能妨碍动物的行动甚至使其瘫痪,而且电极也不可能接触到整个神经系统里的每个神经元。 美国耶鲁大学医学院的神经生物学家将一个来自大鼠的基因植入果蝇体内,这个基因编码一种离子通道蛋白质。在环境中存在生物能量分子ATP的情况下,该离子通道允许带电粒子通过细胞膜,从而传递电脉冲。 果蝇染色体随后,研究者给果蝇注射因为被另一种分子包裹而处于不活动状态的ATP分子。用紫外线激光照射果蝇,能使ATP分子从束缚中解放出来,启动离子通道,使果蝇的神经受到电信号刺激。 实验显示,如果该离子通道蛋白质在控制果蝇爬行的多巴胺能神经元中表达,本来懒散的果蝇在激光照射下会变得过度活跃。如果离子通道表达在控制果蝇逃跑反应的大神经中,则激光可使果蝇跳来跳去、抖动翅膀并飞走。 研究者说,这一技术可用于研究生物的许多其他行为,例如求偶、交配和进食等 果蝇分为白眼和红眼,白眼属于基因突变的结果,是位于X染色体的隐性遗传,因为它只有4对染色体,便于实验观察,常用于研究伴性遗传。美国生物学家摩尔根曾利用这一性状研究基因的连锁与互换定律。 但需注意,果蝇能回交,其生长周期短,但是摩尔根做过回交实验。 果蝇与摩尔根——遗传定律的春天 [1] 摩尔根在遗传学实验中主要是以果蝇为实验材料,他的重要发现都是从果蝇身上取得的。有人说:上帝为了摩尔根才创造了果蝇。 可爱的小果蝇 果蝇是小型蝇类动物,体长只有几个毫米。,上于它喜欢在腐烂水果上飞舞,所以人称果蝇。实际上它喜欢的是腐烂水果发酵产生出的酒,所以酒发酵池前也会招引来很多果蝇,古希腊人称果蝇为“嗜酒者”。 作为实验动物,果蝇有很多优点。首先是饲养容易,用一只牛奶瓶,放一些捣烂的香蕉,就可以饲养数百甚至上千只果蝇。第二是繁殖快,在25℃左右温度下十几天就繁殖一代,一只雌果蝇一代能繁殖数百只。孟德尔以豌豆为实验材料,一年才种植一代。摩尔根最初以小鼠和鸽子为实验动物研究遗传学,效果也不理想。后来经人介绍,摩尔根于1908年开始饲养果蝇。果蝇只有四对染色体,数量少而且形状有明显差别;果蝇性状变异很多,比如眼睛的颜色、翅膀的形状等性状都有多种变异,这些特点对遗传学研究也有很大好处。对于这些有利的特点,摩尔根也不是一下子都认识清楚了的,而是后来在研究工作中逐渐体会到的。 由于摩尔根的实验室中饲养了很多果蝇,研究人员整天在侍候果蝇、观察研究果蝇,所以人称他领导的实验窒为“蝇室”。在摩尔根的领导之下,这个“蝇室”成了全世界的遗传学研究中心。他们的研究成果为全世界遗传学界所注目,他们写出的论文和著作是全世界遗传学家的必读书和重要参考文献。这个“蝇室”还培养出了许多著名遗传学家。 以前苏联的李森科为代表的一些人,曾大肆攻击摩尔根学派以果蝇为主要研究对象是毫无实际意义,是不关心国计民生。事实已经证明这种攻击是站不住脚的。从果蝇身上发现的遗传规律,对其它动植物、对人类也同样适用。理论上有了重要发展,在实践上也必将有重要意义。 发现伴性遗传 摩尔根的实验室起初是用果蝇研究后天获得性状能否遗传的问题。他把果蝇在黑暗环境中连续培养很多代,按照拉马克的用进废退、后天获得性状可以遗传的理论,其视力应该逐渐退化。但是结果不是这样,摩尔根认为这个实验白费功夫了。 摩尔根用果蝇做出了重要的遗传学发现,是从一只白眼果蝇开始的,他由这只白眼果蝇发现了伴性遗传。野生的果蝇眼睛都是红色,但是在1910年时摩尔根发现了一只白眼雄果蝇。按照基因学说,这是发生了基因突变。用这只白眼雄蝇与普通的红眼雌蝇交配,子一代的果蝇都是红眼。按孟德尔学说解释,红眼是显性性状,白眼是隐性性状。子一代的果蝇交配产生出了子二代,结果雌果蝇全是红眼,雄果蝇一半是红眼、一半是白眼。如果不论雌雄,红眼果蝇与白眼果蝇的比例是3:1,符合孟德尔定律。可是为什么白眼都出现在雄果蝇身上呢? 摩尔根也做了回交试验,让子一代的红眼雌蝇与最初发现的那只白眼雄蝇交配,结果生出的果蝇无论雌雄都是红眼白眼各占一半,这也符合孟德尔定律。 摩尔根根据这些实验结果进行了深入思考,他提出了一种假设:决定果蝇眼睛颜色的基因存在于性染色体中的X染色体上雄果蝇的一对性染色体由X染色体和Y染色体组成,Y染色体很小,其上基因很少,所以只要其x染色体上有白眼基因,白眼性状就表现出来。雌果蝇的性染色体是一对x染色体,因为白眼是隐性性状,只有其一对X染色体上都有白眼基因才会表现为白眼性状。根据这种假设,就可以圆满解释上述实验结果。 白眼基因存在于性染色体上,它的遗传规律与性别有关,这就叫:“伴性遗传”。 人色盲的遗传、血友病的遗传,也是伴性遗传。色盲患者多是男性,女性很少,男性色盲患者的子女一般不色盲,可是其外孙中又出现色盲。对这种现象人们过去一直迷惑不解,伴性遗传概念的提出使人明白了其中的奥妙。 发现连锁与交换定律 各种生物染色体的数量是不多的,例如果蝇是4对染色体,豌豆是7对,玉米是10对,人也只有23对。但是,每种生物基因的数量要比其染色体数量多得多。既然基因是存在于染色体上,那么每条染色体上肯定不只有一个基因,而是有许多个。好多人都从理论上做出了这种推测,但是拿不出实验证据,他们根本无法确定某种生物的哪个基因是存在于它的哪一条染色体上。自然科学讲究实证,没有证据时理论是不能得到承认的,至多算是一种合理的假设。 第一个拿出这种证据的是摩尔根,证据来自对果蝇的研究。 在证明白眼突变基因是存在于果蝇的x染色体上之后,摩尔根又发现了残翅突变、朱色眼突变、黄身突变等也是伴性遗传,表明它们的基因也是存在于x染色体上。 孟德尔定律说,在形成配子时成对的基因互相分离,自由组合。根据细胞学研究结果,形成配子时是成对的染色体互相分离,自由组合,所以,只有不在同;条染色体上的基因才可以自由组合,而位于同一染色体上的基因则会连在一起遗传,这就是基因连锁。这种认识也是先从理论上推测出来,然后实验证实。 通过适当地选择交配对象,摩尔根得到了同时具有两种伴性遗传突变的果蝇,如白眼黄身果蝇。他让这种果蝇与普通的野生果蝇或具有不同伴性遗传突变的果蝇交配,果然发现了基因连锁。例如白眼黄身果蝇与野生的红眼灰身果蝇交配,后代中白眼黄身者或红眼灰身者占99%,而没有表现为连锁遗传的即白身灰身者或红眼黄身者,只占1%。 然而连锁并不是百分之百,而且不同基因之间的连锁程度有高有低。摩尔根因此提出,不同染色体之间在形成配子时会发生基因交换,这是由于染色体之间可能发生物质交换而引起的。 摩尔根又进一步想到,同一条染色体上的两个基因,相距越远则发生交换的可能性越大,因此,根据交换率的高低可以判断出基因之间的相对位置。综合大量实验结果、摩尔根绘出了果蝇4对染色体的基因图:把每条染色体上的所有基因排成一条直线,交换率越小的摆的位置愈近。在根本无法直接看到基因的情况下,摩尔根竞然绘出了这样的基因图,人们不得不佩服他的实验工作和逻辑推理都非常严密。 果蝇让位于微生物 摩尔根用果蝇做的遗传学研究,证据确凿地表明基因存在于染色体上,发现了伴性遗传和连锁与交换规律,而且他们对果蝇遗传所做的精细分析还导致这样估计:基因的大小可能类似于最大的有机分子。但是,基因是什么?基因是通过什么方式控制性状呢?直到20世纪30年代仍然一无所知。孟德尔-摩尔根学派遗传学实质上是形式遗传学。虽然基因有物质基础,但是摩尔根用果蝇做的遗传学研究并非是从对基因物质本身的认识出发的,各种结论都是依据实验结果分析推理出来的。 摩尔根想把他的遗传学研究推进到一个新层次,想研究基因是怎样发挥控制性状功能的。 20世纪初时曾有一位英国医生发现黑尿病是遗传性疾病,而且发现黑尿病的病因是患者体内缺少尿黑酸氧化酶,因而不能使尿黑酸分解。他因此提出,基因能控制酶的形成,进而影响代谢过程。 摩尔根的实验室早在30年代用果蝇继续做这方面的研究。他们的实验结果表明,决定果蝇眼睛颜色的物质有一个转化过程,而且他们可以分析出来,哪一种眼色突变是缺少哪一步反应所需要的酶。可是他们无法把有关的各种物质检验和分离出来,实验无法深入。 在生物科学发展迅速的今天,虽然对于生物的研究领域及研究生物逐步多元化,但果蝇作为经典模式生物,在生物学领域的研究和发展有着极其重要的地位。果蝇作为一种模式生物,依旧具有很大的研究潜力。
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