3 research outputs found
An Unusual 500,000 Bases Long Oscillation of Guanine and Cytosine Content in Human Chromosome 21
An oscillation with a period of around 500 kb in guanine and cytosine content
(GC%) is observed in the DNA sequence of human chromosome 21. This oscillation
is localized in the rightmost one-eighth region of the chromosome, from 43.5 Mb
to 46.5 Mb. Five cycles of oscillation are observed in this region with six
GC-rich peaks and five GC-poor valleys. The GC-poor valleys comprise regions
with low density of CpG islands and, alternating between the two DNA strands,
low gene density regions. Consequently, the long-range oscillation of GC%
result in spacing patterns of both CpG island density, and to a lesser extent,
gene densities.Comment: 15 pages (figures included), 5 figure
Quantumlike Chaos in the Frequency Distributions of the Bases A, C, G, T in Drosophila DNA
Continuous periodogram power spectral analyses of fractal fluctuations of
frequency distributions of bases A, C, G, T in Drosophila DNA show that the
power spectra follow the universal inverse power-law form of the statistical
normal distribution. Inverse power-law form for power spectra of space-time
fluctuations is generic to dynamical systems in nature and is identified as
self-organized criticality. The author has developed a general systems theory,
which provides universal quantification for observed self-organized criticality
in terms of the statistical normal distribution. The long-range correlations
intrinsic to self-organized criticality in macro-scale dynamical systems are a
signature of quantumlike chaos. The fractal fluctuations self-organize to form
an overall logarithmic spiral trajectory with the quasiperiodic Penrose tiling
pattern for the internal structure. Power spectral analysis resolves such a
spiral trajectory as an eddy continuum with embedded dominant wavebands. The
dominant peak periodicities are functions of the golden mean. The observed
fractal frequency distributions of the Drosophila DNA base sequences exhibit
quasicrystalline structure with long-range spatial correlations or
self-organized criticality. Modification of the DNA base sequence structure at
any location may have significant noticeable effects on the function of the DNA
molecule as a whole. The presence of non-coding introns may not be redundant,
but serve to organize the effective functioning of the coding exons in the DNA
molecule as a complete unit.Comment: 46 pages, 9 figure
Detection of latent sequence periodicities.
A method is proposed for the automatic detection of serial periodicities in a linear sequence. Its application to DNA subtelomeric sequences from two lower eukaryotes, P.falciparum and S.cerevisiae, reveals ordered patterns organised in hierarchical periodicities, not easily recognizable by other methods. The possible implications concerning the evolution of tandemly repetitive arrays are discussed in light of a model which involves, as successive steps, random repeat modification, the fusion of differently modified repeat versions into longer units, and the amplification of (and/or homogenization to) the more recent repeat units