To study whether the decreased reproduction in insects (Drosophila melanogaster), recorded in authors' previous studies (see "Related articles") after GSM exposure, is accompanied by decreased ovarian development during the developmental period of the first eggs in the ovaries of virgin flies (oogenesis). Oogenesis starts at the late stages of pupation and lasts until about 48 h after eclosion. Furthermore, the authors aimed to verify whether the potential effects were caused by elimination of eggs during early and mid-oogenesis due to DNA damage and cell death induction.
Newly emerged flies were divided into seven groups according to the number of hours following eclosion when they were investigated/dissected (0, 10, 20, 32, 39, 45, 51 h). Additionally, all groups (except 0 h group) were divided into two subgroups: a sham exposed and an exposed subgroup (each group n=8).
For cell death investigation ovarioles were investigated (background information on ovarioles, see Panagopoulos 2007b).
| Exposure | Parameters |
|---|---|
|
Exposure 1:
900 MHz
Modulation type:
pulsed
Exposure duration:
continuous for 6 min., every 10 h (first exposure 3 h after eclosion), max. for 5 times
|
|
| Frequency | 900 MHz |
|---|---|
| Type | |
| Charakteristic | |
| Exposure duration | continuous for 6 min., every 10 h (first exposure 3 h after eclosion), max. for 5 times |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Exposure source | |
|---|---|
| Chamber | antenna of the cell phone in contact with the cylindrical glass vials containing the flies |
| Setup | the mobile phone was held close to the experimenter's head with its antenna facing downward, being at the same time parallel to and in contact with the glass vials; the experimenter spoke to the mobile phone's microphone during connection ("modulated emission") |
| Sham exposure | A sham exposure was conducted. |
| Additional info | no temperature increases during the GSM exposures were recorded within the vials with the insects or within the mass of the food |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 0.795 W/kg | maximum | cf. remarks | - | according to the manufacturer |
| power density | 0.354 mW/cm² | mean | measured | - | ± 0.063 mW/cm² |
| electric field strength | 17.5 V/m | mean | measured | - | ± 3.2 V/m |
| magnetic flux density | 0.08 µT | mean | measured | - | ± 0.02 µT |
The data showed that the ovarian size of the exposed insects was significantly decreased compared with the sham exposed insects. The difference in ovarian size between sham exposed and exposed virgin female flies became significant after two exposures (à 6 min) and was most evident 39-45 h after eclosion (max. decrease 29.75%) when the first eggs within the ovaries were in the stages of mid-late oogenesis.
Data on DNA fragmentation and cell death are not completely shown, but the authors declare that a large percent of DNA damage and cell death was found (average 54.42% TUNEL-positive cells in exposed insects, 6.98% in sham exposed).
In conclusion, the data showed that GSM exposure retarded ovarian development in Drosophila melanogaster and that these effects were caused probably due to a DNA damage and cell death induction in the egg chamber cells during early and mid-oogenesis.
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