Adaptive potential of epigenetic switching during adaptation to fluctuating environments.

Epigenetic regulation of gene expression allows for the emergence of distinct phenotypic states within the clonal population. Due to the instability of epigenetic inheritance, these phenotypes can inter-generationally switch between states in a stochastic manner. Theoretical studies of evolutionary dynamics predict that the phenotypic heterogeneity enabled by this rapid epigenetic switching between gene expression states would be favored under fluctuating environmental conditions, whereas genetic mutations, as a form of stable inheritance system, would be favored under a stable environment. To test this prediction, we engineered switcher and non-switcher yeast strains, in which the uracil biosynthesis gene URA3 is either continually expressed or switched on and off at two different rates (slow and fast switchers). Competitions between clones with an epigenetically controlled URA3 and clones without switching ability (SIR3 knock-out) show that the switchers are favored in fluctuating environments. This occurs in conditions where the environments fluctuate at similar rates to the rate of switching. However, in stable environments, but also in environments with fluctuation frequency higher than the rate of switching, we observed that genetic changes dominated. Remarkably, epigenetic clones with a high, but not with a low, rate of switching can co-exist with non-switchers even in a constant environment. Our study offers an experimental proof-of-concept that helps defining conditions of environmental fluctuation under which epigenetic switching provides an advantage

The role of epigenic mechanisms in the adaptive evolution

"Natural selection acts upon the variation in fitness-related traits within a population. Inheritance of this variation is of paramount importance for this process. Evolution of any inherited trait related to reproductive success will proceed, regardless of its molecular mechanism of inheritance. Mendel´s discoveries and definition of the particulate form of inheritance alongside the discovery that the instructions for phenotypic traits are encoded in the nucleotide sequence within DNA strand lead to the formalization of the Modern Synthesis.(...)

Effects of meteorological conditions on mortality from chronic obstructive pulmonary disease

© 2020, Serbia Medical Society. All rights reserved. Introduction/Objective Previous studies have confirmed the effect of different meteorological parameters on patients suffering from lung diseases. The objective of the study is to investigate the impact of meteorological phases on the death rate from chronic obstructive pulmonary disease (COPD). Methods The data on the number of deaths caused by COPD and meteorological phases during a five-year period (2011–2015) in Šumadija District (Central Serbia) were obtained from the Republic Hydrometeoro-logical Service and the Center for Biostatistics and Informatics of the Kragujevac Institute of Public Health. Results A statistically significant correlation was determined between certain meteorological phases and COPD death rate. The highest death rate was determined during colder months, February and March. The lowest death rate was detected during the warm months (June–September). Although men died more often from COPD than women, the death rate of women showed a considerable increase during the five-year period. Conclusion COPD death rate is highly dependent on the season of the year and might be associated with certain meteorological phases. There is a need for further research of the impact of meteorological phases on the morbidity and mortality from COPD