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Abstract
Geophagy, the deliberate consumption of clay or soil, is a common cultural practice in many
parts of the world, including Nigeria. Although often believed to have therapeutic benefits, some
geophagic clays may contain toxic elements that pose health risks. This study assessed the
toxicity potential of Uzalla geophagic clay by exposing Drosophila melanogaster to varying
concentrations of the clay and assessing their survival rate, locomotor performance, and
neurotoxic gene expression. Flies were exposed to different concentrations of the clay (0.025
g/mL, 0.05 g/mL, and 0.1 g/mL) for five days, and assessments were made on survival rate,
locomotor performance (negative geotaxis), and neurotoxic gene expression. The results revealed
a concentration-dependent decline in survival, with the highest mortality recorded at 0.1 g/mL.
However, negative geotaxis assays indicated improved locomotor performance across all
exposed groups in contrast to the control group, suggesting a possible stimulatory effect. Gene
expression analysis showed upregulation of Spitz, Eiger, and Hedgehog, reflecting activation of
stress and neuroprotective pathways, while Wingless and Keap1 were downregulated, indicating
oxidative imbalance and neuronal disruption. This study shows that Uzalla geophagic clay
exhibited neurotoxic potential at higher concentrations, evidenced by reduced survival, altered
locomotor performance, and disrupted gene expression associated with neural stress.
parts of the world, including Nigeria. Although often believed to have therapeutic benefits, some
geophagic clays may contain toxic elements that pose health risks. This study assessed the
toxicity potential of Uzalla geophagic clay by exposing Drosophila melanogaster to varying
concentrations of the clay and assessing their survival rate, locomotor performance, and
neurotoxic gene expression. Flies were exposed to different concentrations of the clay (0.025
g/mL, 0.05 g/mL, and 0.1 g/mL) for five days, and assessments were made on survival rate,
locomotor performance (negative geotaxis), and neurotoxic gene expression. The results revealed
a concentration-dependent decline in survival, with the highest mortality recorded at 0.1 g/mL.
However, negative geotaxis assays indicated improved locomotor performance across all
exposed groups in contrast to the control group, suggesting a possible stimulatory effect. Gene
expression analysis showed upregulation of Spitz, Eiger, and Hedgehog, reflecting activation of
stress and neuroprotective pathways, while Wingless and Keap1 were downregulated, indicating
oxidative imbalance and neuronal disruption. This study shows that Uzalla geophagic clay
exhibited neurotoxic potential at higher concentrations, evidenced by reduced survival, altered
locomotor performance, and disrupted gene expression associated with neural stress.
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