Identification of the gene-richest regions in chromosomes and nuclei of pig

What is it about?

Here, we describe the compositional organization of the pig genome. We investigated (i) the compositional distribution of the genes by analysis of their GC3 levels (the GC levels at the third codon positions), and (ii) the correlation between the GC3 value of orthologous genes from pig and other vertebrates (human, calf, mouse, chicken, and Xenopus). As expected, the highest gene concentration corresponded to the H3 isochore family, and the highest GC3 correlations were observed in the pig/human and pig/calf comparisons. Then we identified, by in situ hybridization of the GC-richest H3 isochores, the pig chromosomal regions endowed by the highest gene-density that largely corresponded to the telomeric chromosomal bands. Moreover, we observed that these gene-rich bands are syntenic with the previously identified GC-richest/gene richest H3+ bands of the human chromosomes.

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Why is it important?

We observed that the gene-dense region corresponded to the more internal compartment, as previously found in human and avian cell nuclei, which shows that the compositional genome organization fits a 3D organisation at nucleus level. This 3D organisation may be best justified by constraints on gene expression.

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