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標題: | 酵母菌Hsp26蛋白在孢子產生時的作用 The role of yeast Hsp26 in sporulation |
作者: | Tzu-Ming Ho 何子明 |
指導教授: | 董桂書 |
關鍵字: | 酵母菌,熱休克蛋白26,減數分裂, Budding yeast,Hsp26,Meiosis,Sporulation, |
出版年 : | 2005 |
學位: | 碩士 |
摘要: | 在酵母菌減數分裂過程中有一些熱休克蛋白的表現,而這些熱休克蛋白在減數分裂中的功能目前尚未清楚。本論文的目標在於研究酵母菌Hsp26蛋白質在孢子產生時期的功能。Hsp26屬於small heat shock protein superfamily,它除了會受到熱休克而表現,在diauxic shift以及產孢過程中也會表現。
我們發現hsp26突變並不會降低酵母菌的產孢效能,反而會提高了產孢效能。在hsp26突變株細胞中可以發現有一些不正常的孢子產生。從減數分裂時間過程的分析顯示hsp26突變提高了產孢效能是影響在孢子形成的過程。我們假設Hsp26蛋白可能扮演一個紡垂體位置檢控點 (spindle position checkpoint) 的角色,來偵測已完成核分裂的子細胞在母細胞中的位置是否有平均分配而決定孢子形成的過程是否會繼續進行。為了驗證這個假設,我們使用了一些方法來干擾孢子形成的過程。發現當野生型細胞受到高溫處理一段時間後所產生的孢子中,dyads所佔的比例有明顯提高,而在hsp26突變株中則沒有受到影響。我們更進一步的使用benomyl處理細胞,專一性的使減數分裂細胞的紡垂體 (spindle) 發生缺失。結果顯示hsp26突變株並沒有明顯受到影響而野生型的細胞其產孢效能則有明顯降低的現象。另外,我們使用兩個會影響有絲分裂紡垂體方位(spindle orientation)的突變株kar9和dyn1來影響減數分裂時期細胞紡垂體的位置。這個結果也顯示hsp26突變可以隱抑kar9和dyn1所造成的產孢效能缺陷。最後,Hsp26蛋白與一個參與在有絲分裂紡垂體位置檢控點 (mitotic spindle position checkpoint) 的蛋白Tem1有明顯的交互作用,這個結果也支持了我們的假設。綜合所有的結果,我們認為在酵母菌的產孢過程中有一個Hsp26蛋白所參與的紡垂體位置檢控點(spindle position checkpoint),可監控從第二次減數分裂到孢子形成的過程,而確保產生正常的孢子。 In the budding yeast, diploid cells enter meiosis under nutrient starvation. Several heat shock proteins are induced during sporulation. The function of these heat shock proteins is unclear. In this study, we explore the role of Hsp26 in sporulation. Hsp26 is a member of the small heat shock protein superfamily. It is induced by heat shock and accumulates after diauxic shift and during the course of sporulation. The hsp26 mutant does not decrease sporulation; instead, the sporulation frequency in the hsp26 mutant is ~20% higher than that in wild-type cells at 30℃ and ~50% higher at 32.5℃. Meiotic time course studies showed that the increase in sporulation occurs at the step of spore formation. Based on these results, we hypothesize that Hsp26 may play a spindle position checkpoint role in monitoring the distribution of daughter nuclei within the mother cells and in determining whether spore formation should proceed normally. Consistent with this hypothesis, an increase of abnormal asci, such as linear triads, is in the hsp26 mutants. In addition, when wild-type sporulating cells subjected to the reversible thermal treatment yield dyads, however, the hsp26 mutants still produced tetrads mostly. Furthermore, we have used benomyl to specifically cause spindles defects in meiotic cells. The hsp26 mutants are not affected, while the wild-type cells display a defect in sporulation. Additionally, two mutants, kar9 and dyn1, which cause misorientation of mitotic spindles were used to disturb the spindle positioning during meiosis. The results show that the sporulation defects caused by the kar9 and dyn1 mutants could be suppressed by the hsp26 mutation. Finally, the interaction between Hsp26 and Tem1 further suggests that the spindle position checkpoint is involved in our proposed checkpoint machinery. These results demonstrate that there is a novel Hsp26-dependent spindle position checkpoint to control the transition from meiosis II to spore formation. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/24335 |
全文授權: | 未授權 |
顯示於系所單位: | 分子與細胞生物學研究所 |
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