Ayooshi Mitra, Amity University, Kolkata
Some organisms develop an internal switch that can remain hidden for very long or until it is switched on due to stress. Computer cell simulations have evolved over many generations. They disclose why some organisms maintain an un-used switch mechanism that turns on under severe stress, altering some of their features. This maintenance of the unseen switch is a way for the organisms to uphold a higher degree of gene expression stability under normal conditions. In warmer regions, tomato hornworm (Manduca quinquemaculata) larvae are green, making camouflage easier. But in cooler temperatures, they are black( absorb more sunlight). This phenomenon is called phenotypic switching found in some organisms. Generally hidden, in response to dangerous genetic or environmental changes, this switch gets activated. According to Xin Gao (2021), computer simulations are a very powerful tool to mimic the real situation. It allows scientists to observe and comprehend values that are otherwise very difficult to observe through wet laboratory experiments.
A computer simulation of the evolution of 1000 asexual microorganisms, was designed by the researchers in this study. A gene circuit model for the regulation of the expression of a particular protein X was given to each organism. For 90,000 generations, the simulation evolved the population. There were identical non-switching gene circuits in the original founding population and over 30,000 generations, collectively called the ancient population, developed under stable conditions. Called the intermediate population, the next 30,000 generations were exposed to fluctuating environments that shifted every 20 generations. The final 30,000 generations were exposed to a stable environment.
The people in the ancient and derived populations, who evolved in stable environments, both had levels of gene expression optimized for stability. But they were unlike: the stability of the ancient population did not involve phenotypic change, while that of the derived population did. The simulations show that organism populations maintain their switching machinery over a long period of environmental stability by gradually changing low-threshold switches to high-threshold switches when the environment is more stable, easily switched in fluctuating circumstances.
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Image Credits: James Castner, University of Florida
Source:
- https://scitechdaily.com/simulating-evolution-to-understand-a-hidden-genetic-switch/
- Kuwahara, H., Gao, X. Stable maintenance of hidden switches as a strategy to increase the gene expression stability, Nature Computational Science, 62–70 (2021). https://doi.org/10.1038/s43588-020-00001-y
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