Hypomagnetic Field Exposure Alters Iron–Sulfur Homeostasis and Oxidative Balance in a Frataxin-Deficient Insect System

model of frataxin deficiency. Using synchrotron radiation-based X-ray fluorescence (SR-XRF) spectroscopy for in situ elemental analysis in live tissues, we found that HMF significantly altered iron distribution and content in a tissue-specific manner. In frataxin-silenced brains, HMF decreased iron distribution but increased total iron content, whereas in eyes it reduced iron content. Sulfur content decreased in frataxin-deficient eyes but increased in brains under HMF, though its spatial distribution was unchanged. Critically, HMF elevated reactive oxygen species (ROS) in frataxin-deficient brains. Transcriptomic analysis identified 202 differentially expressed genes under HMF in frataxin-silenced flies, including key regulators of iron metabolism and oxidative stress pathways. These findings demonstrate that HMF disrupts tissue-specific iron and sulfur homeostasis and intensifies oxidative stress in a frataxin-deficient insect system, underscoring its role as an environmental factor capable of aggravating metabolic fragility.