Expansion of rDNA and pericentromere satellite repeats in the genomes of bank voles Myodes glareolus exposed to environmental radionuclides

Abstract

Altered copy number of certain highly repetitive regions of the genome, such as satellite DNA within heterochromatin and ribosomal RNA loci (rDNA), is hypothesized to help safeguard the genome against damage derived from external stressors. We quantified copy number of the 18S rDNA and a pericentromeric satellite DNA (Msat‐160) in bank voles ( Myodes glareolus ) inhabiting the Chernobyl Exclusion Zone (CEZ), an area that is contaminated by radionuclides and where organisms are exposed to elevated levels of ionizing radiation. We found a significant increase in 18S rDNA and Msat‐160 content in the genomes of bank voles from contaminated locations within the CEZ compared with animals from uncontaminated locations. Moreover, 18S rDNA and Msat‐160 copy number were positively correlated in the genomes of bank voles from uncontaminated, but not in the genomes of animals inhabiting contaminated, areas. These results show the capacity for local‐scale geographic variation in genome architecture and are consistent with the genomic safeguard hypothesis. Disruption of cellular processes related to genomic stability appears to be a hallmark effect in bank voles inhabiting areas contaminated by radionuclides.

Interpretation of gut microbiota data in the ‘eye of the beholder’: A commentary and re‐evaluation of data from ‘Impacts of radiation exposure on the bacterial and fungal microbiome of small mammals in the Chernobyl Exclusion Zone’

“…the poor‐quality habitat in the Red Forest) rather than exposure to radionuclides! Only by collecting samples from replicate contaminated and uncontaminated areas can location‐specific effects be partitioned from impacts associated with radionuclide exposure (Jernfors et al, 2021; Kesäniemi, Jernfors, et al, 2019; Kesäniemi, Lavrinienko, et al, 2019). The additional discussion points raised by Antwis et al (2021) that ‘Other studies of radiation effects in CEZ wildlife, including the microbiome studies of Lavrinienko et al …, also have their most contaminated sampling sites within the Red Forest…’, and ‘Any study that uses the Red Forest as a location for radiation effect studies on wildlife needs to consider the historical impacts of radiation and other stressors (e.g.…”

The Role of Human Satellite III (1q12) Copy Number Variation in the Adaptive Response during Aging, Stress, and Pathology: A Pendulum Model

“…Expansion of rDNA and MSat-160 pericentromere satellite repeats was revealed in the genomes of bank voles Myodes glareolus exposed to environmental radionuclides within the Chernobyl Exclusion Zone compared to animal subjects from adjacent non-contaminated areas. Notably, 18S rDNA and Msat-160 copy numbers were positively correlated in the genomes of bank voles from uncontaminated areas, but not in the genomes of animals inhabiting contaminated areas [86].…”

“…The animal model described above also corroborates the hypothetically increased viability of organisms carrying increased numbers of satellite copies in their genomes. In the conditions of heightened radiation background, bank vole genomes with increased Msat-160 copy numbers have received a selective advantage in the successive generations [86].…”

Does size‐selective harvesting erode adaptive potential to thermal stress?

“…Phenotypic traits covary genetically (Law, 1991) and phenotypically (Plaistow & Collin, 2014) and it is therefore important to assess multiple traits and understand their interconnectivity as a multivariate phenotype (Pigliucci & Preston, 2004), especially when a population undergoes selection, for example, fisheries selection. in correlated traits in animals exposed to a stressful environment is comparable to a loss of correlation in copy number in genomes of mammals exposed to pollution (Jernfors et al, 2021). Here, we…”

“…We show that covariation in phenotypic traits breakdown under stress, for example, growth rate was no longer correlated with food uptake at either lower or elevated thermal stress. The apparent breakdown in correlated traits in animals exposed to a stressful environment is comparable to a loss of correlation in copy number in genomes of mammals exposed to pollution (Jernfors et al., 2021 ). Here, we show that directional selection drives a shift in average phenotype (i.e.…”