arXiv subjects

Dirk Holste

Publications and source records attributed to Dirk Holste.

3 recordsLinked to original sources

arXiv2004

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.

q-bio.GN↗

arXiv2004

Universal 1/f noise, cross-overs of scaling exponents, and chromosome specific patterns of GC content in DNA sequences of the human genome

Spatial fluctuations of guanine and cytosine base content (GC%) are studied by spectral analysis for the complete set of human genomic DNA sequences. We find that (i) the 1/f^alpha decay is universally observed in the power spectra of all twenty-four chromosomes, and that (ii) the exponent alpha \approx 1 extends to about 10^7 bases, one order of magnitude longer than what has previously been observed. We further find that (iii) almost all human chromosomes exhibit a cross-over from alpha_1 \approx 1 (1/f^alpha_1) at lower frequency to alpha_2 < 1 (1/f^alpha_2) at higher frequency, typically occurring at around 30,000--100,000 bases, while (iv) the cross-over in this frequency range is virtually absent in human chromosome 22. In addition to the universal 1/f^alpha noise in power spectra, we find (v) several lines of evidence for chromosome-specific correlation structures, including a 500,000 bases long oscillation in human chromosome 21. The universal 1/f^alpha spectrum in human genome is further substantiated by a resistance to variance reduction in guanine and cytosine content when the window size is increased.

q-bio.GN↗

arXiv2004

Spectral Analysis of Guanine and Cytosine Fluctuations of Mouse Genomic DNA

We study global fluctuations of the guanine and cytosine base content (GC%) in mouse genomic DNA using spectral analyses. Power spectra S(f) of GC% fluctuations in all nineteen autosomal and two sex chromosomes are observed to have the universal functional form S(f) \sim 1/f^alpha (alpha \approx 1) over several orders of magnitude in the frequency range 10^-7< f < 10^-5 cycle/base, corresponding to long-ranging GC% correlations at distances between 100 kb and 10 Mb. S(f) for higher frequencies (f > 10^-5 cycle/base) shows a flattened power-law function with alpha < 1 across all twenty-one chromosomes. The substitution of about 38% interspersed repeats does not affect the functional form of S(f), indicating that these are not predominantly responsible for the long-ranged multi-scale GC% fluctuations in mammalian genomes. Several biological implications of the large-scale GC% fluctuation are discussed, including neutral evolutionary history by DNA duplication, chromosomal bands, spatial distribution of transcription units (genes), replication timing, and recombination hot spots.

q-bio.GN↗