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標題: | 無脊椎後口動物 FoxP 基因的演化 Evolution of the FoxP gene family in invertebrate deuterostomes |
作者: | Fu-Yu Tsai 蔡馥宇 |
指導教授: | 郭典翰(Dian-Han Kuo) |
共同指導教授: | 游智凱(Jr-Kai Yu),蘇怡璇(Yi-Hsien Su) |
關鍵字: | 演化,發育,FoxP 轉錄因子,頭索動物,半索動物,棘皮動物, Evolution,Development,FoxP transcription factor,Cephalochordate,Hemichordate,Echinoderm, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 基因複製是一種常見的產生新基因的機制。部分旁系同源基因在基因複製之後序列以及功能上會產生變化。脊椎動物的foxp旁系同源基因在胚胎發育過程中扮演多重角色,這些基因可能源自發生於脊椎動物祖先的兩次全基因體複製事件。脊椎動物祖先的FoxP可能經歷過新功能化或是次功能化,進而在脊椎動物的旁系同源基因中產生不同的功能,但目前仍不清楚脊椎動物的FoxP旁系同源基因的功能多樣性是如何自無脊椎動物過渡到脊椎動物的過程中產生。為了對後口類FoxP功能的演化有更多的認識,我分析了頭索動物、半索動物和棘皮動物胚胎發育過程中foxp基因的演化、表現與功能。首先,我建立了FoxP蛋白質的演化分支樹並且分析了無脊椎後口動物中foxp的基因結構。這些結果意味著FoxP家族基因可能源自於脊椎動物祖先的兩次全基因體複製事件,並產生四個旁系同源基因。在文昌魚發育過程中,foxp會表現在中樞神經系統、咽以及腸道等構造,而在海膽和半索動物的胚胎或幼生中,foxp則是表現在腸道周邊以及口部和頂端外胚層。根據FoxP在無脊椎後口動物裡的表現狀況,FoxP很可能在無脊椎後口動物中會影響神經系統。我推論在脊椎動物演化出來之前,FoxP在脊索動物的祖先中可能已經演化出許多新功能,經歷基因複製之後又在脊椎動物進一步產生功能上的特化。此外,我使用反義嗎啉基核酸來抑制在海膽胚胎中FoxP的表現。在經過反義嗎啉基核酸處理的海膽胚胎中,腸發育遲緩。此外,在神經系統中,mbx和isl這兩個轉錄因子的表現也減少,且nk3.2轉錄因子在咽神經元的表現也受到抑制,但在頂端外胚層中nk3.2的表現則不受反義嗎啉基核酸處理影響。相較之下,專門表現在內胚層細胞的轉錄因子foxa則不受反義嗎啉基核酸處理影響。FoxP參與海膽胚胎腸以及咽神經的發育,且這可能是在步帶動物的祖先中FoxP的功能。這些結果提供foxp基因從無脊椎動物過渡到脊椎動物的演化歷史的見解。 Gene duplication is a common mechanism to produce novel genes from pre-existing genes in the same genome. These paralogous genes may diverge in both their sequences and functions after gene duplication. In vertebrates, foxp genes may arise from two rounds of whole-genome duplication events and play diverse roles in vertebrate embryogenesis. These diverse functions may have arisen from neofunctionalization or subfunctionalization among the vertebrate foxp paralogs. However, the detailed process by which the various functions of foxp paralogs arose during the transition from invertebrates to vertebrates is unknown. Here, I characterized the genomic organization, expression, and function of foxp genes in the cephalochordate, the hemichordate, and the echinoderm to elucidate the evolutionary history of foxp genes in the deuterostomes. A phylogenetic tree of FoxP proteins and the genomic structures of foxp in invertebrate deuterostomes were analyzed. Foxp is expressed in the central nervous system, pharynx, and the gut in the amphioxus, while foxp is expressed in the gut as well as in the oral and apical ectoderm in both the sea urchin and the acorn worm. The developmental function of foxp gene in sea urchin was characterized by antisense morpholino oligo-mediated knockdown. In the foxp morphants, gut development was delayed and the expression of neural markers mbx and isl was attenuated, while nk3.2 expression in the pharyngeal neurons was specifically downregulated but not in the apical ectoderm. In contrast, the endodermal cell specification marker foxa was not affected in the foxp morphants. These results suggest that FoxP is involved in the pharyngeal neuron development in the sea urchin, which may represent the ancestral role of FoxP in the common ancestor of Ambulacraria. Moreover, the expression pattern of foxp in amphioxus suggests that FoxP may have acquired new roles in the chordate ancestor before it has duplicated and diverged further in the vertebrates. These results provide insights into the evolutionary history of foxp gene during the transition from invertebrates to vertebrates. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/17243 |
DOI: | 10.6342/NTU202002555 |
全文授權: | 未授權 |
顯示於系所單位: | 生命科學系 |
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