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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/16796

Title: Tbx5基因對斑馬魚心臟肌肉生成之影響及應用生長相關荷爾蒙改善心臟缺損之研究
The impacts of tbx5 gene on embryonic cardiac myogenesis and rescue heart defect using growth related hormones in zebrafish (Danio rerio)
Authors: Sie Lin Choo
朱曦林
Contributors: NTOU:Department of Aquaculture
國立臺灣海洋大學:水產養殖學系
Keywords: 斑馬魚;心臟發育;心肌生成;tbx5
Zebrafish;Heart Development;Cardiomyogenesis;tbx5
Date: 2006
Issue Date: 2011-06-30T08:42:20Z
Abstract: Tbx5屬於T-box家族之轉錄因子,表現於脊椎動物胚胎時期的心臟、前肢和眼睛。以morpholino antisense RNA抑制斑馬魚胚胎tbx5基因,除了會造成胚胎心臟缺損,包括:心臟looping缺損、心室與心房變小、心包膜積水,腹部積水、心跳頻率減緩、無明顯血液流動及amhc、vmhc、cmlc的表現量下降,顯示tbx5基因弱化可造成的心臟缺損皆與心臟肌肉生成基因相關,因此本實驗以斑馬魚作為模式魚種探討tbx5基因對心臟肌肉生成基因之影響。依照心臟缺損之嚴重程度將其分為5個等級:Grade 0 (正常胚胎),Grade I (心臟looping缺損),Grade II (心臟looping缺損且心包膜和腹部有嚴重積水),Grade III (心臟完全無進行looping,心臟構形細長造成心腔變小)和Grade IV (胚胎軀幹嚴重變短,心臟幾乎無法發育)。實驗顯示,心臟肌肉生成基因在斑馬魚胚胎早期即有基礎的表現量,而在心臟進行looping前表現量達到最高。心臟肌肉生成基因在Degree IV,即心臟缺損最嚴重之胚胎中表現最低。以全覆式定位雜交分析tbx5基因被抑制之斑馬魚胚胎之心臟肌肉生成基因有表現異位(ectopic)現象,且心臟無法進行正常looping。此外,tbx5基因被弱化之斑馬魚胚胎之心率也明顯減緩。約4%胚胎出現心臟向左looping。心肌生成在心臟發育以及心臟細胞發育過程中扮演重要的角色,本實驗以可促進心肌生長之及素,包括:hGH、IGF-I及Ghrelin處理tbx5基因弱化的斑馬魚胚胎,以改善心臟缺損的情形。結果顯示,無論在1-4細胞或44hpf時期處理生長相關之荷爾蒙皆可改善胚胎心臟缺損的情形。其中以10 fmole的Ghrelin最為有效。此外,hGH、IGF-I及Ghrelin的處理亦可改善tbx5基因弱化斑馬魚胚胎之心率及減少胚胎心臟向左looping比率。在過高劑量的hGH、IGF-I及Ghrelin的實驗顯示斑馬魚胚胎會出現發育不正常的現象。此外,過高劑量的hGH、IGF-I及Ghrelin反而會抑制心臟肌肉生成基因amhc、vmhc及cmlc2的表現情形,其中以10 fmole的Ghrelin處理組較明顯。推測生長相關荷爾蒙可透過調控心肌生成基因而影響心臟之發育。
Member of the T-box family of transcription factors, tbx5, expresses in the heart, pectoral fins and eyes of zebrafish during embryonic development. In zebrafish, injection of tbx5 morpholino antisense RNA caused changes of heart conformation, defect of heart looping, pericardium effusion, dropsy of ventral position and decreased in heart rate. Meanwhile, expression of cardiac myogenesis genes amhc, vmhc and cmlc2 was decreased dramatically by the knockdown of tbx5 gene. As a result, we demonstrated that cardiac myogenesis genes might responsible for these phenomenons. Hence, zebrafish was used as our model organism in order to ascertain the relationship between cardiac myogenesis genes and heart defect. In previous study, we have established 5 levels of heart defects: Grade 0, Grade I, Grade II, Grade III and Grade IV. Experimental results indicated that cardiac myogenesis genes express constantly at the early embryonic development and reach highest right before cardiac looping. These cardiac myogenesis genes show insufficient expressions within different heart defect degree embryos, especially at Grade IV. Myogenesis genes of heart defective embryos showed ectopic expression of these genes in addition to heart looping defect. Moreover, slower heart rate was observed in these heart defect embryos. Previous studies reviewed that growth related hormones play important roles throughout heart development and cardiomyogenesis. Early and late treatments of hGH, IGF-I and Ghrelin can reduce certain amount of heart defect and survival rate in tbx5 knockdown zebrafish embryos, especially 10 fmole Ghrelin. In addition, hGH, IGF-I and Ghrelin treatments could improve heart rate and decrease the occurrence of leftward-looping heart in tbx5 gene knockdown embryos. Abnormal zebrafish embryos could be detected after over dosage of hGH, IGF-I and Ghrelin treatments, and decreased the expression of amhc, vmhc and cmlc2 gene expression was also found.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M94330015
http://ntour.ntou.edu.tw/ir/handle/987654321/16796
Appears in Collections:[水產養殖學系] 博碩士論文

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