Possible Role of Natural Selection in the Formation of Tandem-Repetitive Noncoding DNA
AUTOR(ES)
Stephan, W.
RESUMO
A simulation model of sequence-dependent amplification, unequal crossing over and mutation is analyzed. This model predicts the spontaneous formation of tandem-repetitive patterns of noncoding DNA from arbitrary sequences for a wide range of parameter values. Natural selection is found to play an essential role in this self-organizing process. Natural selection which is modeled as a mechanism for controlling the length of a nucleotide string but not the sequence itself favors the formation of tandem-repetitive structures. Two measures of sequence heterogeneity, inter-repeat variability and repeat length, are analyzed in detail. For fixed mutation rate, both inter-repeat variability and repeat length are found to increase with decreasing rates of (unequal) crossing over. The results are compared with data on micro-, mini- and satellite DNAs. The properties of minisatellites and satellite DNAs resemble the simulated structures very closely. This suggests that unequal crossing over is a dominant long-range ordering force which keeps these arrays homogeneous even in regions of very low recombination rates, such as at satellite DNA loci. Our analysis also indicates that in regions of low rates of (unequal) crossing over, inter-repeat variability is maintained at a low level at the expense of much larger repeat units (multimeric repeats), which are characteristic of satellite DNA. In contrast, the microsatellite data do not fit the proposed model well, suggesting that unequal crossing over does not act on these very short tandem arrays.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1205784Documentos Relacionados
- Characterization of repetitive DNA in the Mycoplasma genitalium genome: possible role in the generation of antigenic variation.
- THE NATURAL-SELECTION THEORY OF ANTIBODY FORMATION
- The possible role of hypoxia in the formation of axonal bulbs.
- Instability of repetitive DNA sequences: The role of replication in multiple mechanisms
- DNA Sequence Variation in a 3.7-kb Noncoding Sequence 5′ of the CYP1A2 Gene: Implications for Human Population History and Natural Selection