Abstract

The problem of growth regulation in mammals remains an unsolved problem in biology. Systemic and local mechanisms of growth regulation are considered, and the existence of a common gene-regulation program in mammals is discussed. It is reported that genome-wide expression analysis revealed a set of downregulated genes that may be the master-genes of this program. A question arises as to what can lead to evolutionary adjustment to the genetic program of growth regulation in different mammalian species, which, in turn, leads to substantial interspecies differences in morphophysiological characteristics, such as body weight and size, puberty, and life expectancy. Interspecies genome comparison suggests that the genomic distance between gene-regulatory elements may be a factor in the evolutionary adjustment of this program. A strong correlation was found between the adult body mass and length and the genome distance between conserved elements in the vicinities of some mammalian growth-regulating genes. The way in which the chromosomal position of the gene can affect the expression was analyzed. It was found that genomic distance from the gene to the nearest telomere for the somatotropic-axis genes Ghrh and Sst was significantly correlated with the age of maturity in mammals. The gene–telomere distance may also be a factor that modulates the growth-regulation program in mammals.