The rate, not the spectrum, of base pair substitutions changes at a GC-content transition in the human NF1 gene region: implications for the evolution of the mammalian genome structure.
نویسندگان
چکیده
The human genome is composed of long stretches of DNA with distinct GC contents, called isochores or GC-content domains. A boundary between two GC-content domains in the human NF1 gene region is also a boundary between domains of early- and late-replicating sequences and of regions with high and low recombination frequencies. The perfect conservation of the GC-content distribution in this region between human and mouse demonstrates that GC-content stabilizing forces must act regionally on a fine scale at this locus. To further elucidate the nature of these forces, we report here on the spectrum of human SNPs and base pair substitutions between human and chimpanzee. The results show that the mutation rate changes exactly at the GC-content transition zone from low values in the GC-poor sequences to high values in GC-rich ones. The GC content of the GC-poor sequences can be explained by a bias in favor of GC > AT mutations, whereas the GC content of the GC-rich segment may result from a fixation bias in favor of AT > GC substitutions. This fixation bias may be explained by direct selection by the GC content or by biased gene conversion.
منابع مشابه
Investigation of Polymorphisms in Non-Coding Region of Human Mitochondrial DNA in 31 Iranian Hypertrophic Cardiomyopathy (HCM) Patients
The D-loop region is a hot spot for mitochondrial DNA (mtDNA) alterations, containing two hypervariable segments, HVS-I and HVS-II. In order to identify polymorphic sites and potential genetic background accounting for Hypertrophic CardioMyopathy (HCM) disease, the complete non-coding region of mtDNA from 31 unrelated HCM patients and 45 normal controls were sequenced. The sequences were aligne...
متن کاملComparative bioinformatics analysis of a wild diploid Gossypium with two cultivated allotetraploid species
Background: Gossypium thurberi is a wild diploid species that has been used to improve cultivated allotetraploid cotton. G. thurberi belongs to D genome, which is an important wild bio-source for the cotton breeding and genetic research. To a certain degree, chloroplast DNA sequence information are a versatile tool for species identification and phylogenetic implications in plants. Different ch...
متن کاملGene Family: Structure, Organization and Evolution
Gene families are considered as groups of homologous genes which they share very similar sequences and they may have identical functions. Members of gene families may be found in tandem repeats or interspersed through the genome. These sequences are copies of the ancestral genes which have underwent changes. The multiple copies of each gene in a family were constructed based on gene duplicati...
متن کاملDistinct changes of genomic biases in nucleotide substitution at the time of Mammalian radiation.
Differences in the regional substitution patterns in the human genome created patterns of large-scale variation of base composition known as genomic isochores. To gain insight into the origin of the genomic isochores, we develop a maximum-likelihood approach to determine the history of substitution patterns in the human genome. This approach utilizes the vast amount of repetitive sequence depos...
متن کاملRecombination drives the evolution of GC-content in the human genome.
Unraveling the evolutionary forces responsible for variations of neutral substitution patterns among taxa or along genomes is a major issue in the identification of functional sequence features. Mammalian genomes show large-scale regional variations of GC-content (the isochores), but the substitution processes at the origin of this structure are poorly understood. We have analyzed the pattern o...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Genetics
دوره 175 1 شماره
صفحات -
تاریخ انتشار 2007