苔藓动物线粒体基因组的测定及系统发生分析

IOCAS-IR > 海洋环流与波动重点实验室

	苔藓动物线粒体基因组的测定及系统发生分析
其他题名	Sequencing of Bryozoan Mitochondrial Genomes with Analyses of the Phylogeny of Bryozoa
	孙名安
学位类型	博士
	2008-06-06
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	苔藓动物门触手冠动物冠轮动物系统发生线粒体基因组基因排列
摘要	苔藓动物为一类底栖、滤食性、营附着生活的小型水生群体动物。苔藓动物作为重要的海洋无脊椎动物，在生态上具有重要意义，同时在生物活性物质分离等方面也有重要的应用价值。然而目前对于苔藓动物门的分子系统发生研究还相对较少，对于本门的进化地位尚存在许多争议。本门在后生动物中的进化地位尚未得到确定，它同腕足动物门、帚虫动物门、内肛动物门间的进化关系仍然悬而未决，门内部的系统发生关系也未达成一致。本研究采用Long-PCR技术扩增了管孔目苔虫扇形管孔苔虫（Tubulipora flabellaris）和唇口目苔虫颈链血苔虫（Watersipora subtorquata）的线粒体基因组，然后利用DNA文库构建结合引物步移的策略获得了它们的线粒体基因组序列。结果显示它们的线粒体基因组具有一些显著的特点：1. T. flabellaris与W. subtorquata线粒体基因组全长分别为13,763 bp和14,144 bp，与其它后生动物相比较小；2. 两个基因组的最大的非编码区都较小，分别为230 bp和100 bp；3. 两个基因组都编码36个基因，包括12个蛋白质编码基因、2个核糖体RNA基因和22个转运RNA基因。与典型的动物线粒体基因组相比，它们都缺失了atp8基因；4. 通过对基因排列顺序的比较分析发现，T. flabellaris与W. subtorquata的线粒体基因组基因排列顺序与其它后生动物显著不同，相同的基因块（不包括转运RNA基因）最长分别为4个和3个基因。目前已知的四个苔藓动物线粒体基因组的基因排列顺序也非常不同，说明苔藓动物的线粒体基因组经历了大规模的基因重排过程。为了探讨苔藓动物门的进化地位，基于26个后生动物线粒体基因组的11个蛋白质编码基因（不包括atp6和atp8）的氨基酸序列，分别采用最大似然法与贝叶斯法构建分子系统发生树。本研究的结果支持冠轮动物为单系群，触手冠动物位于冠轮动物内部。结果显示毛颚动物与苔藓动物亲缘关系接近，然而这需要更多的证据的支持。最大似然法与贝叶斯分析的结果都支持触手冠动物为多系群，却不支持腕足动物门与帚虫动物门亲缘关系接近构成一个单系群的观点。
其他摘要	The Bryozoa is a group of small, sessile, filter-feeding, aquatic, colonial animals. As important marine invertebrates, bryozoans have important ecological significance; they also have important application in the isolation of bioactive components. However, molecular phylogenetic studies of this group are relatively few. There still many controversy concerning the phylogenetic position of this group. The phylogenetic position of Bryozoa within Metazoa is not determined yet; the relationships of Bryozoa with Brachiopoda, Phoronida and Entoprocta are in dispute. There are still no consensuses on the phylogeny of Bryozoa. In this study, we have amplified the complete mitochondrial genomes of two bryozoans Tubulipora flabellaris (Tubuliporida) and Watersipora subtorquata (Cheilostomida) with Long-PCR technique, then DNA library construction and primer-walking strategies are used to obtain the complete sequences. Their complete mitochondrial genomes have many distinct features: 1. The complete mitochondrial genomes of T. flabellaris and W. subtorquata are 13,763 bp and 14,144 bp in lenth respectively, relatively small compared with mtDNAs of other metazoans; 2. Their largest non-coding retion are also small, of 230 bp and 100 bp in length, respectively; 3. Both of the genomes contain 36 genes, including 12 protein-coding genes, 2 ribosomal RNAs and 22 transfer RNAs. In constrast to the typical animal mitochondrial genomes, both of them are lack of the atp8 gene; 4. Gene arrangement comparisons indicate that complete mitochondrial genomes of T. flabellaris and W. subtorquata both have unique gene order when compared with other metazoans. The longest identical gene blocks (excluding tRNAs) shared with other metazoan mtDNAs are of 4 and 3 genes, respectively. The four known bryozoan complete mitochondrial genomes also have very different gene arrangements, indicates that bryozoan mitochondrial genomes have experienced drastic rearrangements. To investigate the phylogenetic relationship of Bryozoa, phylogenetic analyses based on amino acid sequences of 11 protein coding genes (excluding atp6 and atp8) from 26 metazoan complete mitochondrial genomes were carried out utilizing ML and Bayesian strategies, respectively. Our analyses support the monopoly of Lophotrochozoa. Lophophorate is within the group of Lophotrochozoa. The results indicate close relationship between Chaetognatha and Bryozoa, however, more evidence are needed to clarify the relationship between the two groups. Lophophorate appeared to be polyphyletic according to our analyses, however, neither analysis support close relationship between Branchiopod and Phoronid.
页数	65
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/455
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	孙名安. 苔藓动物线粒体基因组的测定及系统发生分析[D]. 海洋研究所. 中国科学院海洋研究所,2008.

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