To compare the influence of different patterns of intermittent exposures with different intervals, with the effects of continuous exposure of the same total duration of GSM exposure on the reproductive capacity of the fly Drosophila melanogaster.
The aim of the study was to examine whether the various intervals of intermittent exposures would indicate the possible existence of DNA repair mechanisms. A further aim of the study was to evaluate whether GSM irradiation has any effect on the disorganization of the actin-cytoskeleton network, which is another characteristic aspect of cell death in the egg chambers.
Each group consisted of nine female and nine male newly emerged flies kept in separate vials for the first 48 h. After the 48 h, when both males and females of each group were sexually mature, they were put together (nine pairs) in another glass vial and they were allowed to mate and lay eggs for the next 72 h. The flies were exposed by the different patterns of 6 min total daily exposure during the first 5 days of each experiment. On the sixth day there was an additional last exposure and 2-3 h later the parent fIies were removed from the vials. The flies were divided into five exposure groups (one continuous exposure group and four intermittent exposure groups) and one sham exposure group.
For cell death investigation ovarioles were investigated (background information about ovarioles, see Panagopoulos 2007b).
| Exposure | Parameters |
|---|---|
|
Exposure 1:
900 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 6 min./day on 6 days
|
|
|
Exposure 2:
900 MHz
Modulation type:
pulsed
Exposure duration:
1 min. on - 10 min. off, repeated 6 times/day on 6 days
|
|
|
Exposure 3:
900 MHz
Modulation type:
pulsed
Exposure duration:
2 min. on - 10 min. off, repeated 3 times/day on 6 days
|
|
|
Exposure 4:
900 MHz
Modulation type:
pulsed
Exposure duration:
3 min. on - 10 min. off, repeated 2 times/day on 6 days
|
|
|
Exposure 5:
900 MHz
Modulation type:
pulsed
Exposure duration:
3 min. on - 6 hrs off, repeated 2 times/day on 6 days
|
|
Exposure 6:
Exposure duration:
6 min./day on 6 days
|
|
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 6 min./day on 6 days |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source | |
|---|---|
| Setup | mobile phone's antenna in contact with the glass vial containing the insects; phone in speaking mode |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 18.6 V/m | average over time | measured | - | +/- 2.7 V/m |
| magnetic flux density | 0.075 µT | average over time | measured | - | +/- 0.017 µT |
| power density | 0.35 mW/cm² | average over time | measured | - | +/-0.07 mW/cm² |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | 1 min. on - 10 min. off, repeated 6 times/day on 6 days |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 18.6 V/m | average over time | measured | - | +/- 2.7 V/m |
| magnetic flux density | 0.075 µT | average over time | measured | - | +/- 0.017 µT |
| power density | 0.35 mW/cm² | average over time | measured | - | +/-0.07 mW/cm² |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | 2 min. on - 10 min. off, repeated 3 times/day on 6 days |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 18.6 V/m | average over time | measured | - | +/- 2.7 V/m |
| magnetic flux density | 0.075 µT | average over time | measured | - | +/- 0.017 µT |
| power density | 0.35 mW/cm² | average over time | measured | - | +/-0.07 mW/cm² |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | 3 min. on - 10 min. off, repeated 2 times/day on 6 days |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 18.6 V/m | average over time | measured | - | +/- 2.7 V/m |
| magnetic flux density | 0.075 µT | average over time | measured | - | +/- 0.017 µT |
| power density | 0.35 mW/cm² | average over time | measured | - | +/-0.07 mW/cm² |
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | 3 min. on - 6 hrs off, repeated 2 times/day on 6 days |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 18.6 V/m | average over time | measured | - | +/- 2.7 V/m |
| magnetic flux density | 0.075 µT | average over time | measured | - | +/- 0.017 µT |
| power density | 0.35 mW/cm² | average over time | measured | - | +/-0.07 mW/cm² |
| Frequency |
|
|---|---|
| Exposure duration | 6 min./day on 6 days |
| Additional info | sham exposure |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 0 V/m | - | - | - | - |
| magnetic flux density | 0 µT | - | - | - | - |
| power density | 0 mW/cm² | - | - | - | - |
The data showed that intermittent exposure decreased the reproductive capacity and altered the actin-cytoskeleton network of the egg chambers, and that the effect is also due to DNA fragmentation. Intermittent exposures with 10 minutes intervals between exposure sessions were almost equally effective as continuous exposure of the same total duration, whereas longer intervals between the exposures seemed to allow the flies to recover and partly overcome the above-mentioned effects of the GSM exposure.
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