Animal and human populations are increasingly exposed to a high range of environmental pollutants, increasing the genomic instability of these populations, with consequences on their health and life expectations. Many wild mammals are expanding their range, colonizing urban and suburban areas. In occupying human-altered environments, these species are increasingly exposed to various environmental pollutants that may increase their genomic instability affecting the baseline values of cytogenetic markers. A method to search for genomic damage was developed for humans to provide insights into the genotoxic effects of factors related to lifestyle. The assay has been successfully used to evaluate the impacts of environmental stressors, such as atmospheric pollution, dust particles, pesticides and heavy metals, on human health. These xenobiotic factors are equally likely to affect animal populations living in the same environment. Our laboratory is developing protocols to apply this method to different wild populations, e.g. mammals (rodents and ungulates), amphibians and invertebrates. These studies will produce information on the health status of animals living in humandominated landscapes and will inform on the quality of these environments. We propose a research aimed to evaluate the existence of a genomic damage gradient between Eastern grey squirrel Sciurus carolinensis populations living in urban areas compared to populations living in agricultural landscapes. We used the buccal micronucleus test for measuring genomic damage and for detecting both potential clastogenic (chromosome breakage) or aneugenic (chromosome lagging due to dysfunction of mitotic apparatus) effects of different xenobiotics. In particular, micronuclei (MNi) originate from acentric chromosome fragments or whole chromosomes that fail to segregate correctly during mitotic division and appear in the cytoplasm of interphase cells as small additional nuclei. Chromosomal instability was also measured by scoring nuclear buds (NBUDs), representing the elimination process of amplified DNA and excess chromosomes from aneuploid cells. In every population, we collected a sample of exfoliated cells by gently scraping the buccal mucosa of trapped animals. The buccal swap was then stored in a fixative. In the lab, cells were separated by centrifugation and dissolved in a fixative; the solution was seeded on a slide to detect micronuclei with microscopic analysis at 1000× magnification. The study population included 96 subjects sampled in two urban and two agricultural areas. The first urban area (Central area, N=30) was located near the city centre, in a large green area close to the river Po. The second urban area (High traffic area, N=28) was located in a small area attached to a road with a high vehicular traffic (six lanes: three on each side) and close to an exit from the ring road that is widely used to access the city. The other two areas were small private parks southwest of Turin surrounded by intensively agricultural fields. In these areas, we sampled 23 (Area A) and 15 (Area B) animals, respectively. One thousand cells per individual were observed to evaluate the frequencies of MNi and NBUDs, for a total of 96000 analyzed cells. Results showed that the two agricultural area samples did not significantly differ between them in terms of MNi (Mann-Whitney U=152, p=0.555), NBUDs (U=145.5, p=0.425) and total genomic damage (U=132.5, p=0.235); therefore, they were pooled in a single sample representative of the agricultural landscape. Conversely, the Central area had significantly lower values both with respect to the High traffic (U=280, p=0.012; U=263.5, p=0.011 and U=230, p=0.002 for MNi, NBUDs and total genomic damage, respectively) and the agricultural Area A (U=200, p=0.003 and U=215, p=0.015 for MNi and total genomic damage, respectively) and Area B (U=119, p=0.003 and U=130.5, p=0.020 for MNi and total genomic damage, respectively). Interestingly, the High traffic area samples did not significantly differ in terms of cytogenetic markers frequencies with respect to agricultural samples, suggesting an effect of vehicular traffic in determining high levels of genomic damage, comparable with those present in agricultural areas. Our results show that anthropic activities, in terms of vehicular traffic in the urban areas and the use of pesticides in the rural areas, could affect mammal populations in terms of increased levels of genomic damage. The animals in the Central area had much less genomic damage compared to the animals living in the heavily trafficked peripheral area. In recent decades, urban policies have discouraged vehicular traffic in the city centre (e.g. limited traffic and pedestrian areas), moving it to the suburbs. It is known that, in humans, increased levels of MNi are related to increased risk of different types of cancer and other pathologies, such as neurodegenerative and reproductive diseases. Based on this assumption, we can imagine that even in wild mammals, increased levels of genomic damage could be correlated with a reduction in vitality and fitness.

Genomic damage in grey squirrel population living in urban and agricultural areas

Bertolino Sandro
;
Santovito Alfredo
2022-01-01

Abstract

Animal and human populations are increasingly exposed to a high range of environmental pollutants, increasing the genomic instability of these populations, with consequences on their health and life expectations. Many wild mammals are expanding their range, colonizing urban and suburban areas. In occupying human-altered environments, these species are increasingly exposed to various environmental pollutants that may increase their genomic instability affecting the baseline values of cytogenetic markers. A method to search for genomic damage was developed for humans to provide insights into the genotoxic effects of factors related to lifestyle. The assay has been successfully used to evaluate the impacts of environmental stressors, such as atmospheric pollution, dust particles, pesticides and heavy metals, on human health. These xenobiotic factors are equally likely to affect animal populations living in the same environment. Our laboratory is developing protocols to apply this method to different wild populations, e.g. mammals (rodents and ungulates), amphibians and invertebrates. These studies will produce information on the health status of animals living in humandominated landscapes and will inform on the quality of these environments. We propose a research aimed to evaluate the existence of a genomic damage gradient between Eastern grey squirrel Sciurus carolinensis populations living in urban areas compared to populations living in agricultural landscapes. We used the buccal micronucleus test for measuring genomic damage and for detecting both potential clastogenic (chromosome breakage) or aneugenic (chromosome lagging due to dysfunction of mitotic apparatus) effects of different xenobiotics. In particular, micronuclei (MNi) originate from acentric chromosome fragments or whole chromosomes that fail to segregate correctly during mitotic division and appear in the cytoplasm of interphase cells as small additional nuclei. Chromosomal instability was also measured by scoring nuclear buds (NBUDs), representing the elimination process of amplified DNA and excess chromosomes from aneuploid cells. In every population, we collected a sample of exfoliated cells by gently scraping the buccal mucosa of trapped animals. The buccal swap was then stored in a fixative. In the lab, cells were separated by centrifugation and dissolved in a fixative; the solution was seeded on a slide to detect micronuclei with microscopic analysis at 1000× magnification. The study population included 96 subjects sampled in two urban and two agricultural areas. The first urban area (Central area, N=30) was located near the city centre, in a large green area close to the river Po. The second urban area (High traffic area, N=28) was located in a small area attached to a road with a high vehicular traffic (six lanes: three on each side) and close to an exit from the ring road that is widely used to access the city. The other two areas were small private parks southwest of Turin surrounded by intensively agricultural fields. In these areas, we sampled 23 (Area A) and 15 (Area B) animals, respectively. One thousand cells per individual were observed to evaluate the frequencies of MNi and NBUDs, for a total of 96000 analyzed cells. Results showed that the two agricultural area samples did not significantly differ between them in terms of MNi (Mann-Whitney U=152, p=0.555), NBUDs (U=145.5, p=0.425) and total genomic damage (U=132.5, p=0.235); therefore, they were pooled in a single sample representative of the agricultural landscape. Conversely, the Central area had significantly lower values both with respect to the High traffic (U=280, p=0.012; U=263.5, p=0.011 and U=230, p=0.002 for MNi, NBUDs and total genomic damage, respectively) and the agricultural Area A (U=200, p=0.003 and U=215, p=0.015 for MNi and total genomic damage, respectively) and Area B (U=119, p=0.003 and U=130.5, p=0.020 for MNi and total genomic damage, respectively). Interestingly, the High traffic area samples did not significantly differ in terms of cytogenetic markers frequencies with respect to agricultural samples, suggesting an effect of vehicular traffic in determining high levels of genomic damage, comparable with those present in agricultural areas. Our results show that anthropic activities, in terms of vehicular traffic in the urban areas and the use of pesticides in the rural areas, could affect mammal populations in terms of increased levels of genomic damage. The animals in the Central area had much less genomic damage compared to the animals living in the heavily trafficked peripheral area. In recent decades, urban policies have discouraged vehicular traffic in the city centre (e.g. limited traffic and pedestrian areas), moving it to the suburbs. It is known that, in humans, increased levels of MNi are related to increased risk of different types of cancer and other pathologies, such as neurodegenerative and reproductive diseases. Based on this assumption, we can imagine that even in wild mammals, increased levels of genomic damage could be correlated with a reduction in vitality and fitness.
2022
Genomic damage in grey squirrel population living in urban and agricultural areas
Cogne (Aosta)
8-11/06/2022
33 (suppl)
33
33
http://www.italian-journal-of-mammalogy.it/pdf-150740-76387?filename=XII Italian congress of.pdf
Bonaldo Irene, Wauters Luc A., Bertolino Sandro, Santovito Alfredo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1867059
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