Deactivation of TBP contributes to SCA17 pathogenesis

Spinocerebellar ataxia type 17 (SCA17) is an autosomal dominant cerebellar ataxia caused by the expansion of polyglutamine (polyQ) within the TATA box-binding protein (TBP). Previous studies have shown that polyQexpanded TBP forms neurotoxic aggregates and alters downstream genes. However, how expanded polyQ tracts affect the function of TBP and the link between dysfunctional TBP and SCA17 is not clearly understood. In this study, we generated novel Drosophila models for SCA17 that recapitulate pathological features such as aggregate formation, mobility defects and premature death. In addition to forming neurotoxic aggregates, we determined that polyQ-expanded TBP reduces its own intrinsic DNA-binding and transcription abilities. Dysfunctional TBP also disrupts normal TBP function. Furthermore, heterozygous dTbp amorph mutant flies exhibited SCA17-like phenotypes and flies expressing polyQ-expanded TBP exhibited enhanced retinal degeneration, suggesting that loss of TBP function may contribute to SCA17 pathogenesis. We further determined that the downregulation of TBP activity enhances retinal degeneration in SCA3 and Huntington's disease fly models, indicating that the deactivation of TBP is likely to play a common role in polyQ-induced neurodegeneration

Nitrogen removal and microbial community structure of an Anammox-MSBR system

近年來，由於工業開發及農業肥料過度使用，使得許多含氮污染物未經妥善處理即排放至環境中，導致水體含氮化合物含量過高，可能影響生態環境及人體健康。傳統上去除廢污水中氮化物需經由硝化脫硝等複雜程序處理，過程中必須考慮碳源以及溶氧等因素，操作設置成本昂貴，因此學界目前正積極開發研究無氧氨氧化(Anammox)技術。無氧氨氧化作用為自然界中重要的氮循環機制，具此機制之微生物稱無氧氨氧化微生物，屬於自營性微生物，可於無氧環境下，利用CO2作為碳源，將NH4+與NO2-反應形成N2，進而去除水中氮化物。然而，無氧氨氧化微生物生長緩慢，應用於實際廢水處理所需之啟動時間冗長，甚至常有污泥wash-out問題，導致實場化應用仍相當困難。 本研究嘗試以薄膜生物反應器啟動無氧氨氧化系統，藉由適當的植種源選擇、反應槽設計及操作條件控制，期望能夠有效縮短啟動時間。研究結果顯示此反應槽可於3個月內達到穩定除氮效果，氨氮及亞硝酸鹽氮之總去除率於穩定操作下可達95%以上，無機總氮(氨氮、亞硝酸鹽氮及硝酸鹽氮)去除率達60%以上，除氮速率約為0.510 kg-N/m3/day。由系統氮平衡及菌群結構分析可知，系統除氮機制以無氧氨氧化作用為主，脫硝作用及硝化作用則表現不顯著。系統中存在之除氮菌群以無氧氨氧化微生物Candidatus Brocadia sp.及脫硝菌Uncultured Thauera sp.為主，無氧氨氧化微生物數量穩定約為105 ~ 107 copies/μg DNA/ml sample。 長期觀察菌群結構分析顯示，系統操作試驗期間微生物菌相及無氧氨氧化微生物數量穩定，無明顯變化，有助於系統除氮效能提升且穩定系統除氮表現。另外，針對無氧氨氧化微生物功能性基因HZO基因分析之結果顯示，不同氮負荷測試下，此基因之多樣性出現變動，建議可以作為無氧氨氧化系統操作分析之微生物指標之一。由不同水質負荷下之分析結果顯示，氨氮濃度為63.14 mg-N/L，亞硝酸鹽氮濃度為86.42 mg-N/L，為本系統之最佳操作參數。 本研究以薄膜生物反應器啟動無氧氨氧化系統，並以微生物生長代謝特性作為系統操作控制指標，成功建立一套快速啟動無氧氨氧化系統之操作策略，對於未來無氧氨氧化技術應用於實場廢污水處理提供一可行之操作控制技術。In recent years, the impact of nitrogen related pollutants which produced by industrial usage and agricultural fertilizer overuse raises significant concerns. These pollutants are often discharged to the environment without proper treatment. It may affect the ecological environment and human health as well. The traditional wastewater treatments of nitrogen compounds are through the nitrification and denitrification processes. These treatments need advanced operational techniques and could need expensive investigaments. Therefore, the development of alternative nitrogen removing technique such as anaerobic ammonia oxidation (ANAMMOX) process draws tons of attentions to the academic research field. ANAMMOX is an important mechanism of the nitrogen cycle in nature. ANAMMOX bacteria (AMX), a group of the autotrophic microorganism, use CO2 as the carbon source and could metabolize NH4+ and NO2- to form N2. However, there are still many challenges in the application of ANAMMOX system. For example, due the extremely slow growth rate of AMX, start-up of ANAMMOX system requires a lengthly time and needs to avoid biomass wash-out problem as well. The main objective of this study is to start an ANAMMOX system with MBR (membrane bioreactor) design in attempt to shorten the startup time as well as testing appropriate sludge seeding, reactor design and operation parameters. Results showed that the reactor could achieve a stable nitrogen remove in just three months after startup. Efficiency of ammonia and nitrite removal reaches 95% and the removal of inorganic nitrogen (ammonia, nitrite and nitrate) is around 60%. Nitrogen removal rate of the system is about 0.510 kg-N/m3/day. Based on nitrogen balance calculation and microbial community structure analysis, the main mechanism of nitrogen removal in the system is ANAMMOX as the initial proposal. Nitrification and denitrification reaction in the reactor are insignificant. Candidatus Brocadia sp. and Uncultured Thauera sp. are the main bacteria responsible for nitrogen removing in the system. The cell count of AMX is stably maintained at 105 ~ 107 copies/μg DNA/ml sample. Long-term observation of microbial community structure shows that microbial community and the number of AMX are stable throughout the study. Besides regular AMX community analysis, results from testing HZO, one of the AMX functional genes shows that the diversity of HZO gene changed as the nitrogen loading changed. This HZO analysis could be used as the molecular biomarker of the future operational analysis of ANAMMOX system. Ammonia concentration of 63.14 mg-N/L and nitrite concentration of 86.42 mg-N/L are the optimal operation setting of this particular system. In conclusion, using MBR design setup and monitoring the bacterial community could successfully shorten the startup time need for ANAMMOX system. The techniques applied in this study provide an ideal strategy for operation control of ANAMMOX system for wastewater treatment.中文摘要.............................................i Abstract.............................................ii 目錄.................................................iv 圖目錄...............................................vii 表目錄...............................................ix 第一章　前言........................................1 第一節 研究緣起......................................1 第二節 研究目的......................................2 第二章　文獻回顧....................................3 第一節 自然界氮循環..................................3 一、 氮循環機制......................................4 二、 氮循環對環境的影響..............................6 三、 氮循環傳輸模式..................................8 第二節 生物除氮技術..................................10 第三節 無氧氨氧化作用................................11 一、 無氧氨氧化反應..................................11 二、 無氧氨氧化系統..................................12 第四節 無氧氨氧化微生物..............................15 一、 無氧氨氧化微生物生理特性........................15 二、 無氧氨氧化微生物代謝機制........................17 三、 無氧氨氧化微生物生態學..........................19 四、 無氧氨氧化微生物生長特性........................20 五、 無氧氨氧化微生物的種類及演化....................23 六、 分子生物技術應用於無氧氨氧化微生物研究..........24 七、 無氧氨氧化微生物與其他微生物之共生關係..........27 第五節 分子生物技術..................................28 一、 聚合酶鏈鎖反應(PCR).............................28 二、 基因選殖(Cloning)...............................29 三、 變性梯度膠凝電泳(DGGE)..........................29 四、 即時定量聚合酶鏈鎖反應..........................29 第六節 文獻閱讀心得及研究方向擬定....................30 第三章　材料與方法..................................31 第一節 實驗架構......................................31 第二節 實驗設備......................................32 第三節 薄膜生物反應器................................33 一、 薄膜生物反應器之設計............................33 二、 人工合成基質....................................34 三、 系統植種來源....................................35 四、 無氧氨氧化微生物之馴養..........................35 五、 薄膜生物反應器之操作............................36 第四節 系統污泥之批次試驗............................37 第五節 水質分析方法..................................37 一、 氨氮............................................37 二、 亞硝酸鹽氮......................................38 三、 硝酸鹽氮........................................38 四、 sCOD............................................39 第六節 氣體分析......................................39 第七節 菌相分析分法..................................39 一、 DNA萃取.........................................39 二、 聚合酶鏈鎖反應(Polymerase Chain Reaction, PCR)..40 三、 變性梯度膠凝電泳法(DGGE)........................43 四、 DNA序列分析.....................................44 五、 基因選殖 (Cloning)..............................44 六、 即時定量聚合酶鏈鎖反應 (Real-Time PCR)..........45 第四章　結果與討論..................................47 第一節 薄膜生物反應器啟動............................47 第二節 薄膜生物反應器操作情形........................50 一、 系統污泥特性....................................50 二、 系統除氮效能探討................................51 三、 系統批次作用期間氮化物濃度隨時間之變化..........55 四、 系統氮化物濃度變化與ANAMMOX化學平衡關係.........56 五、 系統氮平衡分析..................................57 六、 系統微生物競爭亞硝酸鹽氮分析....................59 七、 系統動力學分析..................................60 第三節 系統菌群結構分析結果..........................62 一、 DGGE定性分析結果................................62 二、 Real-Time PCR無氧氨氧化微生物定量分析結果.......68 第四節 系統污泥之批次試驗結果........................70 一、 初始氮化物濃度對除氮效能的影響..................70 二、 產氣表現與氨氮及亞硝酸鹽氮濃度變化關係..........72 三、 初始氮化物濃度對微生物族群的影響................73 第五節 綜合討論......................................75 第五章　結論與建議..................................77 第一節 結論..........................................77 第二節 建議..........................................79 參考文獻.............................................8

Institutions and growth in Korea and Taiwan: The bureaucracy

How do competent bureaucracies emerge in developing countries? We examine bureaucratic reform in Korea and Taiwan and argue that in both cases political leaders had an interest in reforming the civil service to carry out their programmatic initiatives. In addition, both governments undertook organisational reforms that made certain parts of the bureaucracy more meritocratic, while utilising centralised and insulated pilot agencies' in overall policy coordination. However, we reject the approach to bureaucratic reform that focuses primarily on its efficiency-enhancing effects. If delegation, bureaucratic and policy reform provided an easily available solution to the authoritarian's dilemma, dictators would have more uniformly positive economic records. Rather, we analyse the political and institutional constraints under which governing elites operate. In doing so, we underscore several important variations in the design of bureaucratic organisation, which in turn mirror larger policy differences between the two countries.