靜態電磁場對線蟲之影響 : 由細胞自然凋亡所引起之行為遲緩及加速老化

Abstract

當外加一個靜態電磁場於線蟲成蟲上，磁場強度在150mT以上且影響四天以上，可以使線蟲的爬行速率變慢。而當磁場強度達到200mT且影響八天時，爬行速率會減少八成以上。由及時反轉錄聚合連鎖反應發現，磁場會影響26個與細胞自然凋亡、氧壓以及癌症相關的基因。我們利用TUNEL螢光染色法以及免疫螢光染色法(ced-3抗體)來確認細胞自然凋亡的現象以及位置。並且藉由細胞自然凋亡基因ced-3、ced-4和ced-9的末化突變種來確認。實驗結果證實由磁場所引起的細胞自然凋亡會造成線蟲的爬行速率變慢。 另一方面，我們也發現磁場會加速線蟲的發育。外加200mT的磁場後，線蟲的總發育時間以及壽命都會明顯地減少。由及時反轉錄聚合連鎖反應發現，磁場會影響4個與發育生長及老化相關的基因，分別是clk-1、lim-7、unc-3和age-1。藉由發育以及老化基因的末化突變種，我們確認了磁場會影響發育和老化基因let-7、unc-3和age-1。由實驗結果，我們發現磁場會影響發育以及老化基因clk-1、let-7、unc-3和age-1，進而加速線蟲的發育以及老化。

Adult Caenorhabditis elegans were treated by static electromagnetic fields (static EMF) and the crawling speed was measured. Reduced mobility was observed when magnetic flux density stronger than 150 mT and the duration of treatment longer than 4 days. Eighty percents reduction of mobility occurred when the flux density reached 200 mT and duration of treatment extended to 8 days. Twenty-six differentially expressed genes among apoptosis, oxidative stress, and cancer were identified using quantitative real-time RT-PCR, indicating a globally molecular consequence responding to static EMF. Induction of apoptosis was verified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and immunostaining using antibody against ced-3 gene product. Mutations at genes involved in major apoptotic pathway, i.e. ced-3, ced-4, and ced-9, abolished this static EMF-induced mobility reduction; consistent with the hypothesis that apoptosis is associated with the static EMF-induced mobility reduction. The current study investigated the possible effect of static electromagnetic field (SEMF) on the development and aging process of C. elegans. Nematodes were grown under SEMF of strength from 0 to 200 mT. Development time and lifespan was recorded. Lifespan was reduced from 31 days to 25 days for wild-type nematode. Treatment of 200 mT SEMF reduced development time fro 20% from L2 to L3 stage, 23% from L3 to L4, and 31% from L4 to young adult. Over expressions of clk-1, lim-7, unc-3, and age-1 was verified by quantitative real time RT-PCR. Surveillance of total development time for mutant nematodes elicited the significant reduction for lin-4, lin-14, lin-41, and lim-7, but not for let-7, clk-1, unc-3, and age-1 mutant strains. Lifespan analysis revealed that let-7, unc-3, age-1 was not affected by SEMF treatment. SEMF accelerated the development and shortened the lifespan of nematode through pathways associated with let-7, clk-1, unc-3, and age-1.