Molecular determinants of brain size and cognitive performance
Human Cognitive and Systems Neuroscience
Final Report Abstract
With this study we explored the effects of ionizing radiation on brain size, cognition, and gene expression in wild rodent populations from the Chernobyl Exclusion Zone (CEZ), focusing on two species: the bank vole (Myodes glareolus) and the yellow-necked field mouse (Apodemus flavicollis). These species have been exposed to varying levels of radiation for over 50 generations, making them ideal subjects for investigating the long-term biological impacts of radioactive contamination. Our main goal was to understand the molecular mechanisms driving brain size and cognitive variations in mammals exposed to ionizing radiation. Rodents were sampled from six contaminated and seven uncontaminated sites in and around the CEZ. A total of 320 bank voles and 83 yellow-necked mice were captured for the study. Behavioral tests focused on boldness, exploration, learning, and memory. Metabolic rates were measured using indirect calorimetry, with additional focus on aerobic capacity. We sequenced genomes and transcriptomes, identifying genetic and expression changes related to radiation exposure. We found a significant reduction in brain size in bank voles exposed to high radiation, regardless of geographic location, sex, or age. We further revealed that high radiation exposure was associated with reduced aerobic capacity and self-maintenance in adult rodents, but with higher aerobic capacity in subadults. This suggests metabolic downregulation as a potential protective mechanism against radiation. Our behavioral tests did not show a significant relationship between radiation exposure and cognition, which might be due to a relatively small sample size. Genes related to the immune system were notably affected by radiation, with immune-related genes showing significant enrichment among differentially expressed genes. In addition, we observed changes in gene regulatory networks, particularly in involving immune system and transcription factor genes. Rodents from contaminated areas showed more disrupted gene co-expression networks, with fewer strong gene interactions in the brain regions (except the visual cortex). Our research highlights the complex and subtle genetic responses of wild mammals to chronic radiation exposure. While behavioral and cognitive changes may be limited, there are significant impacts on brain size, metabolism, and gene expression, particularly concerning the immune system. These results may have broader implications for understanding how organisms adapt to extreme environmental stressors like radiation.
Publications
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Poster at Münster Evolution Meeting 2023: “Differential Gene Expression in Eusocial and Solitary Mole Rats: An Analysis of Sociality and Vocalization”
Katja Nowick
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Covariation between metabolic and radioactive dose rates in Chornobyl rodents. openRxiv.
Boratyński, Zbyszek; Lavrinienko, Anton; Lehmann, Philipp; Mousseau, Timothy A.; Tukalenko, Eugene; Vasylenko, Andrii; Watts, Phillip C.; Mappes, Tapio & Nowick, Katja
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Poster at the Annual Meeting of the Society for Molecular Biology and Evolution (SMBE) 2024: Molecular responses of brain functions to chronic low dose ionizing radiation in wild mammals from the Chernobyl Exclusion Zone
Katja Nowick
