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Title: | 以線蚓作為再生研究的模式物種:hedgehog 基因表現之初探 Using Enchytraeus sp. as a model species for regeneration research:a preliminary analysis of hedgehog gene expression patterns |
Authors: | Szu-Huei Chen 陳思卉 |
Advisor: | 郭典翰(Dian-Han Kuo) |
Keyword: | hedgehog,Enchytraeus,寡毛類環節動物,再生,體節生成, hedgehog,Enchytraeus,oligochaete annelid,regeneration,segment formation, |
Publication Year : | 2017 |
Degree: | 碩士 |
Abstract: | Hedgehog 在節肢動物的體節發育中控制體節極性的產生,且它在許多物種的胚胎發育及再生也有相當重要的角色。先前關於環節動物門的研究指出hedgehog 訊息參與多毛類沙蠶胚胎發育及再生時體節的生成,但在環帶綱的水蛭中hedgehog 主要是調控腸道發育而非體節生成。為進一步了解hedgehog 於環節動物體節生成及再生中基因表現的演化,瞭解未被研究hedgehog 的寡毛類,我們分離出同是環帶綱的線蚓的hedgehog 同源基因片段,並調查其表現位置。線蚓Enchytraeus sp.是一種小型、透明的寡毛類環節動物,它藉由斷裂的方式進行無性生殖,可用來研究再生過程中的體節生成過程與機制。本研究所使用的線蚓樣本從台大校園的
土壤中分離出來的,DNA 鑑定顯示為先前未曾被描述過的新種。它可以在切割或是斷裂後三到四天再生出完整尾部,或在六至八天後生成頭部。在完整的線蚓蟲體中,hedgehog 表現在腦部、環帶區的腺體、腸道壁以及在生成體節的後端生長區內。小分子抑制物藥劑測試的實驗顯示hedgehog pathway 可能主要調控線蚓腸道組織的型態恆定在正常的成體。另外,線蚓整個生活史都會表現hedgehog,相較之下同樣是環帶綱的水蛭在發育完後hedgehog 表現大量下降。而在切割過後一至兩天,線蚓的hh 則表現於胚基(blastema)。此外,線蚓的hedgehog 表現分布 於前後端兩種再生有所不同。於後端再生時,線蚓的hedgehog 表現分布與正常的成蟲差異並不大。相較之下,前端再生時,線蚓的hedgehog 表現分布則集中於最前端。依據hedgehog 表現分布顯示在線蚓的前端與後端再生中,hedgehog 可能具有不同的功能角色。本研究為寡毛類環節動物hedgehog 基因表現狀態的首次記錄。 Hedgehog, one of the arthropod segmental polarity genes, is crucial for embryogenesis and regeneration in many metazoan species. Previous studies in annelids showed that hedgehog signaling is involved in segmentation in a polychaete, Platynereis and that hedgehog signaling regulates gut formation but not segmentation in the leech (one clitellate). To understand the evolution of hedgehog expression in annelid segmentation and regeneration, we have isolated a hedgehog homolog (Enc-hh) from Enchytraeus sp., a small transparent microdrile oligochaete reproducing asexually by fragmentation, and studied segment formation during its regeneration. This worm was isolated from the local soil sample, and DNA barcoding suggested that it belongs to a novel, previously undescribed species. It can completely regenerate its tail in 3~4 days and head in 6~8 days after amputation or fragmentation. Enc-hh is expressed in the brain, coelom wall of the clitellum segments, gut, and a site in the posterior growth zone, where the new body segments are formed, in intact worms. The pharmacological disruption experiments suggested that the major function of the hedgehog pathway in the intact worm may be in regulating the morphological homeostasis of the gut tissue. In contrast to the constitutive expression of hedgehog throughout the entire life cycle of Enchytraeus, hedgehog expression is significantly reduced in the post-embryonic stage of the leech. During regeneration, Enc-hh begins to be expressed in blastema two days after amputation. Enc-hh expression patterns differ between anterior and posterior regeneration. During posterior regeneration, Enc-hh expression pattern is similar to an intact worm. On the other hand, Enc-hh expression pattern during anterior regeneration suggests that Enc-hh plays a role in anterior patterning during anterior regeneration. This study revealed different roles of hedgehog during anterior and posterior regeneration in Enchytraeus. This is the first report of hedgehog gene expression pattern in an oligochaete annelid. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60004 |
DOI: | 10.6342/NTU201700128 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 生命科學系 |
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ntu-106-1.pdf Restricted Access | 11.25 MB | Adobe PDF |
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