Oct 12

毒蛇毒牙杀手锏:这个杀手不太冷

作者: 如果爱 iflove.com 自然传奇

蛇类作为自然界的一名神秘杀手,以其美丽的外表征服了这个世界,但又以其毒牙毁掉了自己的名声。其实,大多数蛇类不仅无毒无害,而且还是益虫,就是有毒的蛇类也不会轻易伤人。如果爱www.iflove.com请大家欣赏一组美女蛇的图片,美女的娇柔与毒蛇的野性奇异相融!

中文解说词:蛇类毒牙杀手锏:这个杀手不太冷
English Title: Snake Born to Kill with venom duct fangs?

美女毒蛇杀手

美女毒蛇杀手

(字数:431 撰稿:iflove.com专栏作家陈家伟,转载请注明出处)

关键词:蛇类,美女蛇, 传奇saga下载, 传奇纪录片下载, 北京电视台节目表, 如果爱电视台, 电视节目预告下载, 电视记录片, 传奇节目, 毒蛇

Keywords: Iflove TV, Man and Nature, Animals, Natures, Fabulous Nature, Animal, Saga Download, Documentary Download, Snake, Beauty and the Beast, Adam and Eve, Satan, Garden of Eden, Bible, Snake Girl, Serpent

如果爱 www.iflove.com火爆推出,SAGA传奇节目伴您每一天!即将为您推出的精彩电视纪录片是:《毒蛇毒牙杀手锏:这个杀手不太冷》,自然妙趣不容错过!英文标题:Snake Born to Kill with venom duct fangs? 震撼即将开始,敬请期待!Coming soon……

亲爱的宝贝,在上期节目中,我们向大家介绍了自然界的一号神秘杀手——蛇类。我们知道,蛇类作为自然界的一名神秘杀手,以其美丽的外表征服了这个世界,但又以其毒牙毁掉了自己的名声。

不管我们是否承认,蛇类都是美丽的。它美丽得足以迷惑一切敌人,就让我们人类也不例外。许多蛇类是用毒的高手,它们令天敌闻风丧胆,就连我们人类也不例外。不过话又说回来,凡事不能一概而论。大多数蛇类不仅无毒无害,而且还是益虫,就是有毒的蛇类也不会轻易伤人。所以,千万不要将蛇看作是邪恶的象征。说不定什么时候,它就会躲在黑暗的角落,吞咽枯涩的泪水呢!如果爱www.iflove.com正在讲述蛇类毒牙的传说,精彩正在继续,敬请关注!Coming soon.

后毒牙类毒蛇:The variety of poisonous snakes with venom duct fangs. The toxic Duvernoy’s secretion of thewandering garter snake.Thamnophis elegansuagrans. The unique Duvernoy’s secretion of the brown tree snake (Boiga irregularis).

Nature:毒蛇毒牙的演化。长期以来,人们仅把具有沟牙和管牙的蛇视为毒蛇,然而,近年来发现游蛇科中的虎斑颈槽蛇、红脖颈槽蛇、颈棱蛇、赤健蛇等既无管牙,也无沟牙,却频频发生这类蛇咬伤人后引起中毒的事例,甚至出现被咬伤致严重出血体克死亡的事件.经探人研究后发现,这些蛇虽没有沟牙和管牙,但却具有产生毒性分泌物的毒腺-杜氏腺(Duvernoy’s gland)及皮下腺,且不同的毒腺具有不同的毒性作用,可表现为出血不止、溶血、呼吸困难、肾损害等.这类蛇与毒腺的导管有联系的上颌牙明显粗大,上颌牙与上颌骨、横骨连接牢固,毒腺里的毒液可顺着粗大的上颌牙流入伤口,因此,应视为”后毒牙类毒蛇”.

毒蛇毒牙的演化:本期封面所示为一条蝰蛇(Vipera latastei gaditana),其竖起的毒牙被毒牙鞘盖着。如果爱www.iflove.com摄影:Ruben Schipper

毒蛇毒牙的演化论:对毒蛇所做的一项“演化-发育”研究,得出一个关于蛇的毒牙演化的新模型。蛇毒牙演化是一个有些争议的问题。毒牙的位置不是在上颚的前面就是在上颚的后面,人们所争议的是,这两种安排在演化上是否是相关的。通过观察来自8个物种的96个蛇胚胎的上颚中形成牙齿的上皮,研究人员发现,前毒牙类型和后毒牙类型在形态发生上惊人地相似。前毒牙是从上颚后面一部分发育形成的,这部分在发育过程中被前移;后毒牙是在位置保持不变的一个专门区域发育形成的。该新模型提出,形成牙齿的上皮中后面的一个子区域在发育上变得与剩余的牙齿形成过程脱离关系,从而使后牙能够独立演化,并且在不同毒蛇品种中发生很大改变(与毒腺密切相关)。这一发育事件有可能对新生代高级毒蛇的大规模辐射起到了推动作用,导致了我们今天所看到的极为可观的蛇类多样性。

Nature 454, 630-633 (31 July 2008) | doi:10.1038/nature07178

Evolutionary origin and development of snake fangs

Freek J. Vonk1, Jeroen F. Admiraal1, Kate Jackson2, Ram Reshef3, Merijn A. G. de Bakker1, Kim Vanderschoot1, Iris van den Berge1, Marit van Atten1, Erik Burgerhout1, Andrew Beck4, Peter J. Mirtschin4,5, Elazar Kochva6, Frans Witte1, Bryan G. Fry7, Anthony E. Woods4 & Michael K. Richardson1

1. Institute of Biology, Leiden University, Kaiserstraat 63, PO Box 9516, 2300 RA, Leiden, The Netherlands
2. Department of Biology, Whitman College, Walla Walla, Washington 99362, USA
3. Faculty of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
4. Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5000, Australia
5. Venom Supplies Pty Ltd, Tanunda, South Australia 5352, Australia
6. Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel
7. Department of Biochemistry & Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria 3010, Australia

Correspondence to: Michael K. Richardson1 Correspondence and requests for materials should be addressed to M.K.R. (Email: m.k.richardson@biology.leidenuniv.nl).

Many advanced snakes use fangs—specialized teeth associated with a venom gland1, 2—to introduce venom into prey or attacker. Various front- and rear-fanged groups are recognized, according to whether their fangs are positioned anterior (for example cobras and vipers) or posterior (for example grass snakes) in the upper jaw3, 4, 5. A fundamental controversy in snake evolution is whether or not front and rear fangs share the same evolutionary and developmental origin3, 4, 5, 6, 7, 8, 9. Resolving this controversy could identify a major evolutionary transition underlying the massive radiation of advanced snakes, and the associated developmental events. Here we examine this issue by visualizing the tooth-forming epithelium in the upper jaw of 96 snake embryos, covering eight species. We use the sonic hedgehog gene as a marker10, 11, 12, 13, and three-dimensionally reconstruct the development in 41 of the embryos. We show that front fangs develop from the posterior end of the upper jaw, and are strikingly similar in morphogenesis to rear fangs. This is consistent with their being homologous. In front-fanged snakes, the anterior part of the upper jaw lacks sonic hedgehog expression, and ontogenetic allometry displaces the fang from its posterior developmental origin to its adult front position—consistent with an ancestral posterior position of the front fang. In rear-fanged snakes, the fangs develop from an independent posterior dental lamina and retain their posterior position. In light of our findings, we put forward a new model for the evolution of snake fangs: a posterior subregion of the tooth-forming epithelium became developmentally uncoupled from the remaining dentition, which allowed the posterior teeth to evolve independently and in close association with the venom gland, becoming highly modified in different lineages. This developmental event could have facilitated the massive radiation of advanced snakes in the Cenozoic era, resulting in the spectacular diversity of snakes seen today. www.iflove.com Presents.

蛇类性格总结篇:蛇类作为自然界神秘杀手,以美丽外表征服世界,但又以毒牙毁掉了自己的名声。毒蛇不会轻易伤人,多数蛇类不仅无毒无害,而且还是益虫。欣赏美女蛇图片,美女的娇柔与蛇的野性奇异相融!

不管我们是否承认,蛇类都是美丽的。它美丽得足以迷惑一切敌人,就让我们人类也不例外。许多蛇类是用毒的高手,它们令天敌闻风丧胆,就连我们人类也不例外。

不过话又说回来,凡事不能一概而论。大多数蛇类不仅无毒无害,而且还是益虫,就是有毒的蛇类也不会轻易伤人。所以,千万不要将蛇看作是邪恶的象征。说不定什么时候,它就会躲在黑暗的角落,吞咽枯涩的泪水呢!怎么样,亲爱的,现在就让我们打开如果爱www.iflove.com,一起到电视节目中去倾听毒蛇的委屈吧!

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