There is some ambiguity as "Gc" can refer to different entities. One possible interpretation is that it might be related to genomic guanine-cytosine (GC) content. GC content is a fundamental component of genetic diversity, crucial for phylogenetic analyses [3]. In genomes, the ratio of GC base pairs to the total number of base pairs can influence various biological processes. GC pairs are generally more stable than AT pairs, and in prokaryotes, there is a positive correlation between growth temperature and GC content, suggesting thermal adaptation [2].

In gerbil genomes, a large genomic region with extreme GC-content has been discovered. Recombination, through GC-biased gene conversion (gBGC), increases the local GC-content in genomic regions. In gerbils, this high-GC region is characterized by high substitution rates for all mutational categories. Additionally, over 300 genes outside the known region have outlying values of AT-to-GC synonymous substitution rates, with over 30% organized into at least 17 large clusters. This suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, leading to a runaway increase in GC-content [1].

In conclusion, GC content, whether in terms of overall genomic GC levels or local GC-biased evolution, plays significant roles in various biological processes such as evolution, adaptation to environmental conditions like temperature, and potentially in the context of genomic stability and rearrangement. The study of gerbil genomes provides a powerful model to understand the mechanisms of gBGC and the rapid evolution of GC-content in mammals [1].

References:

1. Pracana, Rodrigo, Hargreaves, Adam D, Mulley, John F, Holland, Peter W H. . Runaway GC Evolution in Gerbil Genomes. In Molecular biology and evolution, 37, 2197-2210. doi:10.1093/molbev/msaa072. https://pubmed.ncbi.nlm.nih.gov/32170949/

2. Hu, En-Ze, Lan, Xin-Ran, Liu, Zhi-Ling, Gao, Jie, Niu, Deng-Ke. 2022. A positive correlation between GC content and growth temperature in prokaryotes. In BMC genomics, 23, 110. doi:10.1186/s12864-022-08353-7. https://pubmed.ncbi.nlm.nih.gov/35139824/

3. Xian, Qing, Wang, Suyin, Liu, Yanyan, Kan, Shenglong, Zhang, Wei. 2023. Structure-Based GC Investigation Sheds New Light on ITS2 Evolution in Corydalis Species. In International journal of molecular sciences, 24, . doi:10.3390/ijms24097716. https://pubmed.ncbi.nlm.nih.gov/37175423/