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题名	扁形动物蛋白酶比较基因组学研究与适应性进化
作者	程菁菁
学位类别	硕士
答辩日期	2012-05
授予单位	中国科学院研究生院
授予地点	北京
导师	文建凡
关键词	蛋白水解酶 扁形动物 比较基因组学 血吸虫 适应性进化
其他题名	Comparative genomics analysis of the Platyhelminthes degradome and their adaptive evolution
学位专业	细胞生物学
中文摘要	蛋白水解酶(protease)在生物中广泛存在，能够水解蛋白质底物中的肽键，具有多种重要的生理功能。不同生物之间蛋白水解酶的比较基因组学研究可以使我们加深对它们的认识。扁形动物包括三种类别的生物，分别是营自由生活的涡虫，寄生生活的吸虫与绦虫，吸虫与绦虫虽然都是寄生生活，但寄生环境与营养取食方式迥然不同。这些不同可能会导致蛋白水解酶产生与之相适应的不同生物学特点。本文对不同扁形动物之间的蛋白水解酶进行比较基因组学分析，调查蛋白酶在不同类型的扁形动物中的多样性及各自的特点。并着重对血吸虫的整个蛋白水解酶进行了适应性进化研究。获得如下主要结果和结论： 首先通过对几种扁形动物的基因组的同源搜索寻找基因组中的蛋白酶。对三类扁形动物两两之间特有的蛋白酶进行功能上的比对，发现涡虫相比于吸虫和绦虫具有更多特有的蛋白酶，并且这些蛋白酶的功能更多，参与的生物过程也更多样；吸虫与绦虫各自所特有的蛋白酶相对涡虫较少，并且基本属于和涡虫相同的功能。相对于吸虫和绦虫，涡虫独特的蛋白酶的功能体现在诸如运动，与神经系统发生相关的生物粘附等方面。这些差别与涡虫和两类寄生虫之间的生理特点和生活环境的差异相一致，涡虫营自由生活，运动机能和神经系统等方面更加发达，而吸虫和绦虫因为寄生，这些机能相对退化，因此涡虫的蛋白酶系统比吸虫和绦虫更加发达。两类同是寄生虫的吸虫和绦虫相比：它们各自特有的蛋白酶在功能上也有所不同，但都是与基本的生命活动相关的。吸虫内部的血吸虫与华支睾吸虫相比，蛋白酶数目和种类都很相似，这与它们较近的亲缘关系及相似的生活方式是一致的。 对吸虫类蛋白酶的进一步比较分析发现，血吸虫蛋白酶发生了一系列与该生物特定的寄生生活相关的适应性进化。如：产生了特有的降解宿主皮肤的弹性蛋白酶，利于入侵宿主，金属蛋白酶的M08家族呈特异性扩增，在血吸虫入侵宿主时降解宿主皮肤。还产生了特有的半胱氨酸酶Legumain，在消化宿主血红蛋白时发挥重要作用。另外消化宿主血红蛋白的组织蛋白酶D明显曾经受到正选择。
英文摘要	Proteases distribute widely in organisms, their catalytic function is to hydrolyze peptide bonds, and they have many important physiological functions. Comparative genomic analysis of proteases between different categories may help us to understand them better. There are three categories of organisms in Platyhelminthes, including the free-living planaria and the parasitic trematode and tapeworm. Although the trematode and tapeworm are both helminths, their living environments and feeding ways are obviously different The differences may result in the proteases producing some corresponding biological characteristics, especially in parasites. We compared the proteases among different platyhelminthes for researching their diversity and respective traits. Then a further research with emphasis onSchistosome proteases for adaptive evolution was done. The followings were concluded: . We firstly perform homologous search on genomes of several platyhelminthes. Then multiple comparison of the functions of thier specific proteases among three categoryies of platyhelminthes was performed. The results of the comparison among planaria, trematode and tapeworm show that planaria have the most proteases, and those proteases have more functions and join more biological processes. Trematode and tapeworm possess of less specific proteases than planaria, their functions are approximately the same as planaria. Compare to trematode and tapeworm, the specific proteases of planaria are mainly have functions on movement, biological adhesion and so on. Those divergences are consistent with the different life styles and living environment between planaria and two parasitic worms. The free-living planaria develop better than trematode and tapeworm in locomotion, nervous system and so on, while the latter degenerate in those ssaspects because of autoeciousness, so planaria have more development protease system. The comparison between trematode and tapeworm found that their proteases are different in several functions, but this functions are mainly basal biological processes. The comparison between Schistosome and Clonorchis sinensis revealed similar numbers and kinds of proteases. This is related to their near evolutionary relationship and similar life styles. We also make a further analysis on proteases of Schistosome, the result revealed that Schistosome proteases have happenedwhich are related to the parasitic life. For example, the cercarlae elastases for degradation of skin are only possessed by trematode. It is beneficial for invasion. The M08 family of Metallo Proteases is expanded in Schistosome, which is also important for invasion. There are a kind of specific Cysteine Protease, Legumain, who play an important role in digestion. In addition, the cathepsin D also play it’s role in digestion. And it was subject to positive selection in history. a series of adaptive evolution
语种	中文
公开日期	2012-09-25
内容类型	学位论文
源URL	[http://159.226.149.42:8088/handle/152453/7118]
专题	昆明动物研究所_真核细胞进化基因组
推荐引用方式 GB/T 7714	程菁菁. 扁形动物蛋白酶比较基因组学研究与适应性进化[D]. 北京. 中国科学院研究生院. 2012.

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