The study of the GC content pattern is important because it reflects the environment to which bacteria belong and provides insights into how bacteria evolve. Many studies have focused on the effect of environmental factors on the DNA on bacteria, and ultraviolet radiation (UVR) is one of the most widely investigated factors. Among many theories about the effect between UV radiation and genomic GC content, we studied a doubtful theory that had not been well refuted, proposed by Singer and Ames in 1970 on Science. They proposed the positive correlation between bacterial genomic GC content and UVR, mainly supported by their measurement of the GC content of bacteria living in environments with different different UVR and the analysis on the protective mechanisms of bacteria against UVR. The article written by Bak, Atkins and Mayer in 1972 refuted Singer and Ames' proposal by presenting exceptions of unicellular organisms that do not follow the correlation and proposed the theory that the distribution of GC content is not much affected by UVR, showing a random state. Restricted by contemporary technology and academic progress, the two articles both lack direct measurements of genome arrangement, and they do not explain the detailed mechanisms behind their theories. In this paper, the arrangement of thymine in bacteria is measured, and the result contradicts Singer and Ames' theory, agreeing with Bak, Atkins and Mayer's theory. The possible explanation of mechanisms is summarized behind, which further supports Bak, Atkins and Mayer's theory. In other words, we have more precisely assessed and refined an old debatable theory by using modern technology and academic achievements.

Nuofan Yang. Random Distribution of Bacterial GC Content under the Ultraviolet Radiation. Frontiers in Medical Science Research (2024), Vol. 6, Issue 5: 1-8. https://doi.org/10.25236/FMSR.2024.060501.

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