蝙蝠苦味受体T2R16的进化动态和功能分化
文献类型：学位论文
| 作者 | 周熊福 |
| 学位类别 | 硕士 |
| 答辩日期 | 2011-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 施鹏 |
| 关键词 | 直系同源基因 旁系同源基因 T2R16 正选择 功能分化 水杨苷 |
| 其他题名 | Evolutionary Dynamic and Functional Divergence of Bitter Taste Receptor T2R16 in Bats |
| 学位专业 | 神经生物学 |
| 中文摘要 | 直系同源基因是指从单个祖先基因垂直遗传下来的基因，即与物种分化（speciation）相联系；旁系同源基因是指由于基因重复（duplication）而产生的基因。一般认为，直系同源基因拥有相似的功能，而旁系同源基因趋向于拥有不同的功能。然而，随着大规模基因组数据的积累和全基因组的分析等，传统的观点受到越来越多的争议。 本文将以蝙蝠苦味受体T2R16为研究对象，T2R16在蝙蝠里以直系同源基因和旁系同源基因两种形式存在，并且旁系同源基因的出现时间较短，可以作为探讨二者进化动态和功能演化的模型。通过PCR扩增，测序和荧光定量PCR等方法获得了26条蝙蝠的T2R16，其中14条为直系同源基因，12条为分布在鼠耳蝠属四个物种的旁系同源基因。直系同源基因和旁系同源基因总体上的选择压力分析表明，二者受到相近的净化选择。受正选择作用的位点分析表明，二者都有受正选择作用的位点，但是其数量和分布有较大的差异，提示着其进化机制上可能存在着差异。同时，我们还发现T2R16直系同源基因在菊头蝠的共同祖先有潜在的正选择作用，以及T2R16基因树在狐蝠科内部与物种树不一致，提示着在直系同源基因内可能会出现功能上的分化。为此，我们构建了T2R16的功能表达载体，用体外细胞实验做了进一步的验证。功能实验表明，蝙蝠T2R16直系同源基因和旁系同源基因有着相似的命运，即都存在对特定苦味物质功能上的丢失，以及对特定苦味物质敏感性的差异。T2R16旁系同源基因MFI_1和MFI_2对水杨苷无反应，另两个拷贝MFI_3和MFI_4保持着对水杨苷的反应，提示着T2R16在物种MFI中可能出现亚功能化。 |
| 英文摘要 | Orthologs are genes originated from a single ancestral gene by vertical descent, which is related to speciation. Paralogs are genes related by duplication. It is widely accepted that orthologs tend to have similar function and paralogs tend to have different functions. However, this idea is challenged with the rapid accumulation of large-scale genomic data and comparative genomic studies. In our research, we chose bat T2R16 to explore the evolutionary pattern and functional divergence between orthologs and paralogs, owing to T2R16 existing in bats in these two forms and the paralogs emerging in a short time. Through combining different methods of PCR (polymerase chain reaction) amplification, sequencing, real-time PCR etc, 26 sequences of T2R16 were obtained, including 14 orthologs and 12 paralogs which distributed in 4 species of myotis. And then, we conducted evolutionary analysis respectively. The selection pressure detection indicated that both T2R16 orthologs and paralogs underwent a similar overall purifying selection. Despite of this overall purifying selection, we indentified positively selected sites in both T2R16 orthologs and paralogs. Intriguingly, great differences were observed in terms of the site number and distribution, which may suggest that different evolutionary mechanisms acted on T2R16 orthologs and paralogs. At the mean time, we found out that, in T2R16 orthologs, the ancestor of Rhinolophoidea showed a positive selection and T2R16 gene tree conflict with bats species tree for the Pteropodidae clade. These two interesting finding indicated that functional divergence could happen in T2R16 orthologs. To test this prediction, we constructed T2R16 functional expression vectors and conducted the cell-based functional assays in vitro. The results implied that the fate of T2R16 orthologs and paralogs were similar. That is, both could encounter loss of function and sensitivity divergence for detecting a particular bitter compound. Additionally, two copies of T2R16 paralogs, MFI_1 and MFI_2, showed no response to salicin, while the other two copies, MFI_3 and MFI_4, maintained the ability of response to salicin, which could suggest that subfunctionalization had happened for T2R16 in species MFI. |
| 语种 | 中文 |
| 公开日期 | 2011-09-19 |
| 源URL | [http://159.226.149.42:8088/handle/353002/6788]  |
| 专题 | 昆明动物研究所_进化与功能基因组学 |
| 推荐引用方式 GB/T 7714 | 周熊福. 蝙蝠苦味受体T2R16的进化动态和功能分化[D]. 北京. 中国科学院研究生院. 2011. |
入库方式： OAI收割
来源：昆明动物研究所
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