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【答案】应助回帖
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sltmac(金币+50): 2011-08-23 14:45:08
sltmac(金币+50): 2011-08-23 14:45:12
sltmac(金币+20, 翻译EPI+1): 2011-08-23 14:45:18
sltmac: 帮你要过来了~~ 2011-08-23 14:45:34
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In this study, we attempt to construct molecular phylogenetic trees based on the nuclear 18S rRNA and ITS gene sequences of the symbiotic algae obtained from hydra sinensis and GenBank and the homologous sequences of the representative species from non-symbiotic, free-living green algae within Chlorella genus that belongs to Class Trebouxiophyceae, preliminarily discussing phylogenetic relationships between the symbiotic algae from different sources and free-living algae in Class Trebouxiophyceae, thus confirming whether the origin of symbiotic algae was polyphyletic or monophyletic. Currently, 18S rRNA sequences of symbiotic algae from difference sources seem abundant, so phylogenetic trees(figure3-2,figue3-3,figue3-4) based on 18S rRNA sequences of symbiotic algae and free-living green algae within Class Trebouxiophyceae provides a wealth of genetic information for us. The ML(figure3-2)、MP(figure3-3) and Bayesian trees(figure3-4) based on 18S rRNA gene sequences all indicated that 61 Species of Class Trebouxiophyceae related to trees construction were separated into two branches, one branch was symbiotic algae group which consist of endosymbiotic algae from hydra, paramecium, ginkgo and moss and many free-living algae, and the other branch was free-living algae group which consist only of free-living algae. The result suggests that，from the perspective of Class Trebouxiophyceae broad framework, the symbiotic algae from different sources seem to have a common origin; but from the perspective of symbiotic algae group small framework, Symbiotic algae from different sources do not form a monophyletic group exclusively, but mix with other free-living algae in phylogenetic trees and do not seem to have a common origin. |
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