ELF alternating magnetic field decreases reproduction by DNA damage induction.

Abstract

In the present experiments, the effect of 50-Hz alternating magnetic field on Drosophila melanogaster reproduction was studied. Newly eclosed insects were separated into identical groups of ten males and ten females and exposed to three different intensities of the ELF magnetic field (1, 11, and 21 G) continuously during the first 5 days of their adult lives. The reproductive capacity was assessed by the number of F1 pupae according to a well-defined protocol of ours. The magnetic field was found to decrease reproduction by up to 4.3%. The effect increased with increasing field intensities. The decline in reproductive capacity was found to be due to severe DNA damage (DNA fragmentation) and consequent cell death induction in the reproductive cells as determined by the TUNEL assay applied during early and mid-oogenesis (from germarium to stage 10) where physiological apoptosis does not occur. The increase in DNA damage was more significant than the corresponding decrease in reproductive capacity (up to ~7.5%). The TUNEL-positive signal denoting DNA fragmentation was observed exclusively at the two most sensitive developmental stages of oogenesis: the early and mid-oogenesis checkpoints (i.e. region 2a/2b of the germarium and stages 7-8 just before the onset of vitellogenesis)-in contrast to exposure to microwave radiation of earlier work of ours in which the DNA fragmentation was induced at all developmental stages of early and mid-oogenesis. Moreover, the TUNEL-positive signal was observed in all three types of egg chamber cells, mainly in the nurse and follicle cells and also in the oocyte, in agreement with the microwave exposure of our earlier works. According to previous reports, cell death induction in the oocyte was observed only in the case of microwave exposure and not after exposure to other stress factors as toxic chemicals or food deprivation. Now it is also observed for the first time after ELF magnetic field exposure. Finally, in contrast to microwave exposure of previous experiments of ours in which the germarium checkpoint was found to be more sensitive than stage 7-8, in the magnetic field exposure of the present experiments the mid-oogenesis checkpoint was found to be more sensitive than the germarium.

AI evidence extraction

Main findings

Exposure to a 50-Hz alternating magnetic field (1, 11, 21 G) for 5 days decreased reproductive capacity by up to 4.3%, with larger decreases at higher field intensities. Increased DNA fragmentation (TUNEL-positive signal) and consequent cell death were reported in reproductive cells during early and mid-oogenesis, with DNA damage increases reported up to ~7.5%.

Outcomes measured

• Reproductive capacity (number of F1 pupae)
• DNA damage (DNA fragmentation; TUNEL assay)
• Cell death induction in reproductive cells during oogenesis

Limitations

• Sample size not reported in abstract (number of replicate groups/experiments unclear).
• Magnitude of reproductive decrease reported as small (up to 4.3%).
• Details of exposure setup (e.g., field uniformity, sham control conditions) not described in abstract.
• Statistical methods/significance levels not provided in abstract.

Suggested hubs

• animal-studies (0.9)
  Experimental ELF magnetic-field exposure study in Drosophila assessing reproduction and DNA damage.

{
    "study_type": "animal",
    "exposure": {
        "band": "ELF",
        "source": "alternating magnetic field",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "continuous exposure during first 5 days of adult life"
    },
    "population": "Drosophila melanogaster (newly eclosed; groups of 10 males and 10 females)",
    "sample_size": null,
    "outcomes": [
        "Reproductive capacity (number of F1 pupae)",
        "DNA damage (DNA fragmentation; TUNEL assay)",
        "Cell death induction in reproductive cells during oogenesis"
    ],
    "main_findings": "Exposure to a 50-Hz alternating magnetic field (1, 11, 21 G) for 5 days decreased reproductive capacity by up to 4.3%, with larger decreases at higher field intensities. Increased DNA fragmentation (TUNEL-positive signal) and consequent cell death were reported in reproductive cells during early and mid-oogenesis, with DNA damage increases reported up to ~7.5%.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract (number of replicate groups/experiments unclear).",
        "Magnitude of reproductive decrease reported as small (up to 4.3%).",
        "Details of exposure setup (e.g., field uniformity, sham control conditions) not described in abstract.",
        "Statistical methods/significance levels not provided in abstract."
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF",
        "50 Hz",
        "alternating magnetic field",
        "Drosophila melanogaster",
        "reproduction",
        "oogenesis",
        "DNA fragmentation",
        "TUNEL",
        "apoptosis",
        "cell death"
    ],
    "suggested_hubs": [
        {
            "slug": "animal-studies",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Experimental ELF magnetic-field exposure study in Drosophila assessing reproduction and DNA damage."
        }
    ]
}

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