報告書番号

U97095

タイトル（和文）

大腸菌のタンパク質発現におよぼす極低周波磁界の影響

タイトル（英文）

EFFECT OF EXTREMELY LOW FREQUENCY MAGNETIC FIELDS ON PROTEIN SYNTHESIS IN ESCHERICHIA COLI

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究では，磁界応答メカニズムの解明を最終目的とし，環境因子（ストレス）に対する遺伝子発現応答に関して知見の多い大腸菌を用い，磁界暴露に対して再現性のある応答の有無を検討した。磁界暴露には，当所の開発した高磁界発生装置を用いた。大腸菌の全タンパク質を二次元電気泳動法により解析したところ，約１，０００種類のタンパク質が一度に検出できた。また，大腸菌に５０度，３０分の熱ストレスを与えたところ，熱ストレスタンパク質（ｈｓｐ７０）を含む少なくとも８種類のタンパク質の発現に再現性のある変化が見られた。一方，周波数５－１００Ｈｚ，最大１４ｍＴｒｍｓの正弦波回転円磁界を３０分および６．５時間暴露したが，再現性のある顕著なタンパク質発現変化は確認できなかった。以上のことから１４ｍＴｒｍｓ以下の低強度の極低周波磁界は，遺伝子転写やタンパク質合成といった生体の基本的な機構に対し，作用しないことが示された。

概要 （英文）

THE EFFECT OF EXTREMELY LOW-FREQUENCY (ELF) MAGNETIC FIELDS (MFS) ON PROTEIN SYNTHESIS IN ESCHERICHIA COLI K12 WAS INVESTIGATED. A WIDE-RANGE EXPOSURE SYSTEM WAS OCNSTRUCTED FOR GENERATING 2-AXIS SINUSOIDAL ELF-MFS IN THE FREQUENCY RANGE OF 0 HZ (STATIC) TO100 HZ WITH A MAXIMUM INTENSITY OF 10 MTRMS (BELOW 60 HZ,14 MTRMS FOR VERTICAL CIRCULARLY POLARIZED MF). THE BACTERIAL CELLS WERE INCUBATED IN LB MEDIUM IN AN ANNULAR-SHAPED CULTURE VESSEL (OUTSIDE DIAMETER:20 CM,INSIDE DIAMETER:15 CM) AT 30 DEGRREE +- 0.2 DEGREE UNDER AEROBIC (AERATION:2L/MIN) OR ANAEROBIC CONDITIONS (NO AGITATION). THE BACTERIAL CELLS UNDER AEROBIC CONDITIONS WERE EXPOSED TO MFS (5 HZ-100 HZ) AT THE MAXIMUM INTENSITY. THE CELLS UNDER ANAEROBIC CONDITIONS WERE ALSO EXPOSED TO THE CIRCULAR POLARIZED MF AT 50 HZ (14 MT) FOR 16 H. 2-D ELECTROPHORESIS WAS CARRIED OUT TO ESTIMATE THE CHANGE IN PROTEIN SYSNTHESIS USINGTHE METHOD OF THE SWISS-2DPAGE ONLINE DATABASE. ABOUT 1,000 PROTEINS WERE SEPARATED BY THE 2-D METHOD (PI 4.0-8.0,MW <200 KDA) FOR THE BACTERIAL CELLS. STRESS RESPONSE PROTEINS,SUCH AS DNAK (HSP70),CH60,AND CH10,ETC.,WERE ALSO DETECTED. AN INCREASE IN THE SYNTHESIS LEVELS OF THESE STRESS PROTEINS WAS OBSERVED IN HEAT-SHOCKED CELLS (50 DEGREE FOR 30 MIN). NO SIGNIFICANT AND NO REPRODUCIBLE CHANGE IN PROTEINS SYNTHESIS,INCLUDING STRESS RESPONSE PROTEINS,WAS OBSERVED AT EXPOSURE TO VERTICAL CIRCULARLY POLARIZED MFS AT 5 HZ (14 MTRMS),10 HZ (14 MTRMS),20 HZ (14 MTRMS),30 HZ (14 MTRMS),40 HZ (14 MTRMS),50 HZ (14 MTRMS),60 HZ (14 MTRMS),70 HZ (12.6 MTRMS),75 HZ (11.9 MTRMS),80 HZ (11.2 MTRMS),90 HZ (9.8 MTRMS) OR 100 HZ (7.7 MTRMS) UNDER AEROBIC CONDITIONS FOR 6.5 H. THERE WAS NO SIGNIFICANT CHANGE IN THE PROTEIN SYNTHESIS AT EXPOSURE TO 50 HZ (10 MT) MF FOR 30 MIN. UNDER ANAEROBIC CONDITIONS,NO SIGNIFICANT CHANGE IN PROTEIN SYNTHESIS WAS OBSERVED. THESE RESULTS INDICATE THAT ELF-MFS AT THE INTENSITIES USED IN THIS RESEARCH DO NOT INDUCE ANY CHANGES IN PROTEIN SYNTESIS INCLUDING STRESS RESPON

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