著者

外村 泰子 上口 勇次郎

出版者

東京女子大学

雑誌

一般研究(C)

巻号頁・発行日

1994

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マイクロ波の生体への障害を究明する実験は、1)上口がin vitroのヒト精子懸濁液にマイクロ波を照射し、染色体異常の出現を調査した。2)外村はマイクロ波の熱作用を、ショウジョウバエの唾腺染色体上のパフ誘発から調査した。3)マイクロ波照射対象をショウジョウバエの卵母細胞として、X-染色体不分離がF_1バエで検出されるかを調査した。1)〜3)までの実験は、電子レンジ周波数2.45GHz、出力500Wで5秒、10秒、出力200Wで60秒被爆させる処理方法ですすめた。1)の結果:in vitroのヒト精子では(1)被爆後照射時間による差は認められるが、精子懸濁液の温度の上昇がみられ、精子運動率も低下した。(2)生存した精子は、ハムスター卵に異種間受精をさせ染色体分析を行なった。マイクロ波による特定な染色体異常の増加の傾向はなく、このことはDNA損傷を生ぜめしないとして上口の実験は終了した。2)の結果:(1)マイクロ波被爆ではAshburner(1972)の記載による熱ショックパフと、新しいパフ誘発も観察された。(2)37℃、40分間湯煎器内で幼虫を飼育した時、唾腺染色体上のパフは逆に消滅する減少を示した。上述のことからマイクロ波特有な熱作用については1996年に、分子生物学的分野からの実験により追求したい。(3)の結果:(1)ある遺伝子系の雌株にマイクロ波を照射し、直ちに+雄株と交配させて羽化したF_1バエを数えた。性染色体異数体バエの検出からは対象群との間には差がなかった。この事実は上口の実験同様、マイクロ波による影響は陰性である。結果を明白にするため1996年は、対象郡にX線照射(400r)処理実験を計画する。(2)再度の実験時で、翅の奇形バエの発生、致死変異誘発による蛹から成虫バエへの羽化妨害などが見られた。1996年にはマイクロ波の特有な作用の決め手を電気泳動法から掴みたい。

著者

外村 泰子

出版者

東京女子大学

雑誌

Science reports of Tokyo Woman's Christian University (ISSN:03864006)

巻号頁・発行日

vol.46, no.3, pp.1393-1397, 1996-03-15

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Tis study was conducted using Drosophila melanogaster oocytes as one of a series of experiments to ascertain the effects of microwaves on living bodies. Fujikawa et al. reported in 1994 that treating Drosophila melanogaster oocytes with carbon dioxide induced sex chromosome non-disjunction. The effects of microwaves on living bodies may be confirmed if exposing oocytes to microwaves generates more heteroploidies of sex chromosomes than those generated in the control group. Materials and Method Used: The present author obtained yw^iec/B^sYsc^8 y stocks (female adults used for microwave-exposure test) and mwhjv; spa^<pol>+stocks (male adults). Oocytes of P (y stocks, female parent) were exposed to microwave (using a home-use microwave oven, with a frequency range of 2.45GHz) for 5 seconds and for 10 seconds with an output of 500W and for 60 seconds with 200W. The non-disjunction of X chromosomes was detected in F_1 using the following steps. Results and Discussion: The phenotype of y-stock females had yellow bodies and ivory-colored eyes, while the+stock males had wild-type-color bodies and red eyes. Next-generation female flies from the mating those with red eyes had wild-type-color bodies and red eyes while males had yellow bodies and ivory-colored eyes. However, if sex chromosomes non-disjunction is induced, females will have XXY sex chromosomes; that is, flies with phenotypes will have yellow bodies and ivory-colored eyes. Male flies will have XO sex chromosomes, wild-type bodies, and red eyes. The results of the experiment are shown in Table 1. Out of 5511 flies of the control group, F_1, there were two females and three males due to the induction of sex chromosome non-disjunction. Out of the 3768 F_1 flies exposed to microwaves for five seconds with an output of 500W, these emerged four females and one male, while out of the 3148 flies exposed to 500W for 10 seconds, one female and two males emerged; out of 935 exposed to 200W for 60 seconds, only one male with non-disjunction was induced. No difference was found in the number of heteroploidies between the control group and the experimental group. The results suggest that there were no effects of microwave exposure on sex chromosome non-disjunction. It is clear from the above experiment that there were no effects of microwave exposure on oocytes, although a slight difference was noted in the number of F_1 flies due to trauma caused by the difference in output of the microwave oven or the duration of exposure (Table 1). The present author thinks that an additional experiment is required one in which oocytes exposed to X-rays are used as a control group, in order to verify the results of this experiment. Fujikawa et al. reported in 1994 that the frequency of F_1 heteroploidies increased in the experimental group when oocytes were treated with carbon dioxide for 45 minutes or longer during the metaphas of the first meiotic division. They pointed to the non-disjunction induction mechanism caused by carbon dioxide as the reason for this phenomenon. They also suggested that extracellular CO_2 plus oxygen deficit evoke cellular conditions that damage the spindle body and thereby affect the normal segregation of homologous chromosomes later. They also reported that they had a negative result from a similar experiment using oocytes exposed to X-rays.

著者

上口 勇次郎 立野 裕幸 渡邉 誠二 外村 泰子

出版者

東京女子大学

雑誌

Science reports of Tokyo Woman's Christian University (ISSN:03864006)

巻号頁・発行日

vol.45, no.3, pp.1297-1303, 1995-03-08

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This study was undertaken to examine the cytogenetic effects of microwaves on human spermatozoa, using an interspecific in vitro fertilization system between human spermatozoa and zona-free hamster oocytes. Ejaculated human spermatozoa were exposed in vitro to microwaves from a household electronic range (2.45GHz, 500W) for 5 (Group I) and 10 seconds (Group II). The average temperatures of the sperm suspensions were 29℃ in the non-irradiated control, 38℃ in Group I, and 54℃ in Group II immediately after the microwave irradiation. After irradiation, about 10% of the spermatozoa became immotile in Group I, as did about 50% of the spermatozoa in Group II, due to the heat stress. A total number of 474 spermatozoa were karyotyped in the control: 386 spermatozoa, in Group I, and 506 spermatozoa, in Group II. The incidences of spermatozoa with structural chromosome aberrations were 11.3±1.4%, 11.5±1.6% and 10.3±2.0% in the control and Groups I and II respectively, showing no statistically significant difference between the three groups. The numbers of aberrations per spermatozoon were 0.140±0.023, 0.127±0.027, and 0.123±0.028 respectively in the three groups, also showing no significant difference between them. These results indicate that neither microwave irradiation nor heat stress has a clastogenic effect on human sperm chromosomes.