Single-celled organisms can mutate by accidental changes to their genetic code. This feature of single-celled organisms is a large driver of evolution and leads to speciation (the process of generated new species from a common ancestor). Mutations are subject to natural selection; when mutations confer a trait that is beneficial to the organism in their environment, the changes are carried on to future generations and stick around. When mutations confer a trait that is detrimental to the organism, they are unlikely to be passed on to future generations and are lost.
Genetic code changes can happen in several ways: through accidents made by genetic code copiers when they multiply, through genetic code copiers that purposefully make frequent mistakes during stressful situations, and now research is showing through “loneliness” of single-celled organisms. Of course, these organisms aren’t capable of feeling “lonely” per se, but being alone in a location means that certain signals from other organisms are missing. Without these signals, according to Krašovec, Richards and colleagues, single-celled organisms are more likely to make mistakes copying their genetic code, leading to mutations.
By studying 70 years of mutation research across all three domains of life (Bacteria, Archaea and Eukaryota), and viruses, they discovered a “negative correlation” between mutation and population density. This means that when there are more cells in a single location, the cells have some means of sensing the presence of neighboring cells, and are less likely to have accidental changes to their genetic code. They also verified this with experiments in the lab that show that specific proteins that scavenge for a molecule, called 8-oxo-dGTP – a modified form of a genetic building block – are required for the mutation to occur. The precise link between these proteins and likelihood of genetic code mutations remains to be fully understood, and requires more research.
This research is particularly important in the treatment of infections. When people consume an antibiotic to treat an infection, it dramatically lowers bacterial numbers in their body. This research suggests that the few bacteria that survive antibiotic treatment may be more likely to change their genetic code. By doing this, these bacteria can acquire traits that make them resistant to antibiotics, helping create infections that are untreatable by conventional antibiotics. This new understanding can help scientists find ways to slow the process of bacteria turning from regular bugs into untreatable superbugs.
Summary written by: Landon Getz
To read the full paper, please click the following link:
Spontaneous mutation rate is a plastic trait associated with population density across domains of life
Rok Krašovec, Huw Richards, Danna R. Gifford, Charlie Hatcher, Katy J. Faulkner, Roman V. Belavkin, Alastair Channon, Elizabeth Aston, Andrew J. McBain, Christopher G. Knight