固定磁場(static magnetic field,簡稱SMF)在醫療方面的應用漸廣，磁場對生物體影響相關的研究亦與日俱增，而本實驗室使用線蟲為生物模組，探討固定磁場與生物體致癌現象的相關性。在我們的研究中，主要分為兩個部分:第一部分主要是以線蟲為生物模組探討SMF誘導生物體發育加速以及致癌現象之間的關係。我們發現在200 mT SMF的處理之下加速了線蟲的發育，縮短了線蟲每個生長發育分期所需時間的20%~30%。在發育調控基因的分析結果發現:有磁場處理的組別，蟲體的clk-1, lim-7, daf-2, unc-3及age-1的表現量都較未經磁場處理的蟲體來的高;在let-7, clk-1, unc-3及 age-1突變種的分析試驗結果和基因表現分析結果是一致的。從實驗結果分析發現:經由SMF誘導產生的發育加速現象可能經由let-7, clk-1, unc-3, 及age-1所調控的路徑產生。
第二部分則是延續第一部分所發現的現象更進一步探討: SMF誘導產生的老化現象主要可能和哪些關鍵基因有相關連性。在前一部分的實驗發現:經由200 mT SMF處理下，正常線蟲的壽命會從31天提早到25天。而在老化蛋白lipofuscin, 爬行速率，生殖能力等老化指標分析發現:經200 mT磁場處理的線蟲皆有提早老化的現象產生。進一步的老化基因分析顯示:經200 mT磁場處理的線蟲，其體內調控老化表現的基因(lim-7, age-1, daf-2)表現量皆比未處理組別高出20~1500倍以上。而在clk-1, eat-2, daf-2, daf-16, age-1及unc-3的突變種分析試驗的呈現結果是與前述老化分析實驗一致的。
癌症的生成主要是由細胞不正常的生長造成，而失序的生長主要來自於細胞無法正常傳遞遺傳訊息和及時修補遺傳序列上的錯誤訊號。當發育過程被加速，使得遺傳訊息錯誤配對的機率提高；而老化現象提早，將會使得遺傳訊息傳遞錯誤的修補率下降，導致錯誤的遺傳訊息被傳遞下去，進而可能導致細胞失序生長，甚至是癌症的產生。根據我們的實驗結果發現:長時間在超過200 mT以上的磁場暴露之下，會加速生物體的發育速率並且提早生物體老化現象的產生，這可能與長期在磁場暴露之下工作者的罹癌率較高有相關性。

With the application of static magnetic field (SMF) in clinical practice, the incidence of exposure has largely increased. We investigated the correlation between SMF and cancer production with Caenorhabditis elegans as an animal model. Here are two parts in our study. Firstly, we were focused on the SMFs-induced acceleration for the development and cancer production in C.elegans model. Treatment with a 200 mT SMF reduced the development times about 20 ~ 31%. The total developmental time was significantly reduced for the lin-4, lin-14, lin-41, and lim-7 mutants, but not for the let-7, clk-1, unc-3, and age-1 mutants. Lifespan analyses revealed that the let-7, unc-3, and age-1 mutants were not affected by SMF treatment. Here we show that SMFs accelerate nematode development and shorten nematode lifespan through pathways associated with let-7, clk-1, unc-3, and age-1.
Secondly, we were focused on the genetic control for aging process under the influence of SMF in C. elegans model. After SMF treatment, the average lifespan was reduced from 31 days to 25 days for wild-type nematodes. And the results of representative experiments in aging analysis, lipofuscin accumulation, crawling speed, and reproductive ability, indicated 200 mT SMF accelerate the aging process. The 20 ~ 1500 times up-regulation of aging genes (lim-7, daf-2, and age-1) after 200 mT SMF treatment was verified by quantitative real-time RT-PCR. And the results of the clk-1, eat-2, daf-2, daf-16, age-1, and unc-3 mutant-type analysis are coincidence with the aging assay.
The cancer production is according to the abnormal cell proliferation. And the uncontrollable cell proliferation attributes to the transcription messages mistake and missing in transcription messages mistake repaired. The mismatch probability of transcription messages communicating was increased during accelerated development; the repair rate of wrong transcription messages was decreased during aging. These make the wrong transcription messages pass down, and then induce abnormal cell proliferation, even cancer production. According to our studies, over 200 mT SMF exposures would accelerate the development and aging process. And this may explain why people exposures with SMF for a long time get cancer with high proportion.

Contents .................................................................................... I
Chapter 1: Introduction ..................................................................... 1
1.1 General Introduction to static magnetic field .............................................................. 1
1.2 Static magnetic fields................................................................................................... 1
1.3 The effects of static magnetic fields at cellular level .................................................. 2
1.4 The effects of static magnetic fields at multicellular organisms ................................. 2
1.5 The effects of static magnetic fields in Mammals ....................................................... 3
1.6 A leading animal model system - Caenorhabditis elegans ......................................... 5
1.7 Aging alterations of Caenorhabditis elegans .............................................................. 9
1.8 Motivation ................................................................................................................... 9
Chapter 2: Experiment and Method .................................... 10
2.1 Chemicals ................................................................................................................... 10
2.2 Static Magnetic Fields ................................................................................................ 10
2.3 Strains of Caenorhabditis elegans ............................................................................. 10
2.4 Isolation of Nematode Developmental Stages............................................................ 11
2.5 Lifespan assay ............................................................................................................ 11
2.6 Lipofuscin analysis ..................................................................................................... 12
2.7 Mobility assay ............................................................................................................ 12
2.8 Reproduction analysis ................................................................................................ 12
2.9 Quantitative real-time RT-PCR .................................................................................. 13
2.10 Statistical Analyses ................................................................................................... 14

Chapter 3: Result .............................................................................. 16
3.1 A SMF of 200 mT shortens the lifespan of C. elegans .............................................. 17
3.2 SMFs stronger than 150 mT accelerate nematode development time ........................ 18
3.3 Genes associated with development and aging are differentially expressed after treatment with SMFs ........................................................................................................ 21
3.4 Nematodes mutant for developmental and aging genes are resistant to SMF-induced life cycle reduction .......................................................................................................... 22
3.5 Nematodes mutant for developmental and aging genes are resistant to SMF-induced lifespan reduction ............................................................................................................. 24
3.6 SMFs shortened the lifespan of C. elegans ................................................................ 27
3.7 SMF at 200 mT reduced the mobility of wild-type, daf-2, and daf-16 adult C. elegans 29
3.8 SMF promoted early expression of lipofuscin ........................................................... 31
3.9 SMF promoted the egg laying of C. elegans .............................................................. 31
3.10 SMF extended the reproductive span of C. elegans ................................................. 33
3.11 Real time RT-PCR revealed over expression of clk-1, age-1, unc-3, and let-7 under the influence of SMF ........................................................................................................ 34
Chapter 4: Discussion ............................................................ 37
4.1 SMFs accelerate the development and aging of nematodes ..................................... 37
4.2 Global effects of SMFs ............................................................................................. 38
4.3 Triggering effects of SMFs on transcription ............................................................. 39
4.4 Genetic analyses of mutants revealed possible mechanisms underlying the SMF-induced gene expression ........................................................................................ 39
Chapter 5: Conclusions ......................................................... 41

List of Abbreviations ............................................................. 44
References .......................................................................... 45

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