A-to-I RNA editing是一種改變RNA序列的後轉錄修飾機制，可以增加基因產物的複雜性。ADAR (adenosine deaminase that act on RNA)是負責催化此一反應的酵素，在脊椎動物表現三種ADAR，分別為ADAR1、ADAR2、ADAR3。本實驗室針對ADAR2 exno1b/intron1b連接處設計antisense morpholino，並以顯微注射到斑馬魚受精卵，降低斑馬魚ADAR2蛋白質的表現量。E1b/i1b morphant胚體發育過程不正常，異常的表現型包括身體較小、MHB（midbrain hindbrain boundary）不明顯、後腦隆起、第三及第四腦腔隆起、對碰觸不敏感、最慢在胚體發育七天內死亡。為進一步瞭解ADAR2 e1b/i1b antisense morpholino如何影響斑馬魚胚體發育並造成不正常的表現型，我們分析一些神經發育相關的基因在morphant的表現，瞭解上述神經發育異常的原因。這些基因包含與促進MHB發育的基因（paxb和eng3）、影響前腦發育的基因（pax6a、dlx2a和shha）、與rhomobomere r3及r5分化相關的krox20、早期神經細胞分化的標示基因ngn1及表現在許多神經細胞之鈉離子通道基因zNav1.6。發現上述這些基因在野生種和e1b/i1b morphant胚體的表現區域及表現量都相似，表示e1b/i1b morphant胚體的MHB、前腦、後腦、神經細胞分化、分佈和活化不受到ADAR2 e1b/i1b antisense morpholino的影響。最後稍微探討5’-UTR morphant和e1b/i1b morphant胚體二者的異常表現型雖相似，但二種morphant的zNav1.6、krox20及crystallin αA mRNA表現區域不一致的可能原因。

The A-to-I (adenosine to inosine) RNA editing changing RNA sequence is a post-transcriptional modification mechanism which increases complexities of gene products. ADADs (adenosine deaminase that act on RNA) are the enzymes catalyzed the deamination of A to I. The e1b/i1b antisense morpholino which annealed to the junction between exon1b and intron1b of ADAR2 pre-mRNA was injected into zebrafish embryos to block the splicing of ADAR2 RNA. E1b/i1b morphant embryos developed abnormally. The abnormal phenotypes inclued small bodies, bulging hindbrain and brain ventricles, touch insensitivity, and death before 7 dpf. To understand the defects of neuronal development in the e1b/i1b morphant, the expression patterns of several neuronal markers were studied by in situ hybridization. No significant differences in the expression patterns of the midbrain hindbrain boundary (MHB), forebrain, hindbrain, neuroblast and neuronal markers between wild-type and e1b/i1b morphant embryos were observed. These results showed that ADAR2 e1b/i1b antisense morpholino has no apparent influence on the gene expressions in the MHB, forebrain, hindbrain and neurons, suggesting that the regionalization and development of these brain regions were not perturbed in the e1b/i1b morphant. The results observed in the e1b/i1b morphant. The results observed in the e1b/i1b morphant, however, differed from those observed in the 5'-UTR morphant created by injecting antisense morpholino complementary to the 5'-UTR.

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