Motivation: Analysis of statistical properties of DNA sequences is important for evolutional biology as well as for DNA probe and PCR technologies. These technologies, in turn, can be used for organism identification, which implies applications in the diagnosis of infectious diseases, environmental studies, etc.
Results: We present results of the correlation analysis of distributions of the presence/absence of short nucleotide subsequences of different length ('n-mers', n = 5-20) in more than 1500 microbial and virus genomes, together with five genomes of multicellular organisms (including human). We calculate whether a given n-mer is present or absent (frequency of presence) in a given genome, which is not the usually calculated number of appearances of n-mers in one or more genomes (frequency of appearance). For organisms that are not close relatives of each other, the presence/absence of different 7-20mers in their genomes are not correlated. For close biological relatives, some correlation of the presence of n-mers in this range appears, but is not as strong as expected. Suppressed correlations among the n-mers present in different genomes leads to the possibility of using random sets of n-mers (with appropriately chosen n) to discriminate genomes of different organisms and possibly individual genomes of the same species including human with a low probability of error.
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http://dx.doi.org/10.1093/bioinformatics/bth266 | DOI Listing |
Phys Chem Chem Phys
April 2011
William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH 43210, USA.
We have combined static pressure, spectroscopic temperature, Fourier transform infrared spectroscopy (FTIR), and small angle X-ray scattering (SAXS) measurements to develop a detailed picture of methanol condensing from a dilute vapor-carrier gas mixture under the highly supersaturated conditions present in a supersonic nozzle. In our experiments, methanol condensation can be divided into three stages as the gas mixture expands in the nozzle. In the first stage, as the temperature decreases rapidly, small methanol n-mers (clusters) form, increase in concentration, and evolve in size.
View Article and Find Full Text PDFJ Chem Phys
February 2011
School of Chemistry, University Park, University of Nottingham, NG7 2RD Nottingham, United Kingdom.
The photoionization of enantiomerically pure epichlorohydrin (C(3)H(5)OCl) has been studied using linearly and circularly polarized vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum was recorded and the first three bands assigned using molecular orbital calculations for the expected conformers, although uncertain experimental conformer populations and an anticipated breakdown in Koopmans' theorem leave some ambiguity. Measurements of the photoelectron circular dichroism (PECD) were obtained across a range of photon energies for each of these bands, using electron velocity map imaging to record the angular distributions, during which a record PECD chiral asymmetry factor of 32% was observed.
View Article and Find Full Text PDFJ Biol Phys Chem
December 2005
Department of Computer Science, University of Houston, Houston, TX 77204, USA.
It is shown that the presence/absence pattern of 1000 random oligomers of length 12-13 in a bacterial genome is sufficiently characteristic to readily and unambiguously distinguish any known bacterial genome from any other. Even genomes of extremely closely-related organisms, such as strains of the same species, can be thus distinguished. One evident way to implement this approach in a practical assay is with hybridization arrays.
View Article and Find Full Text PDFBioinformatics
October 2004
Department of Computer Science, University of Houston, TX 77204-3010, USA.
Motivation: Analysis of statistical properties of DNA sequences is important for evolutional biology as well as for DNA probe and PCR technologies. These technologies, in turn, can be used for organism identification, which implies applications in the diagnosis of infectious diseases, environmental studies, etc.
Results: We present results of the correlation analysis of distributions of the presence/absence of short nucleotide subsequences of different length ('n-mers', n = 5-20) in more than 1500 microbial and virus genomes, together with five genomes of multicellular organisms (including human).
Electrophoresis
May 2000
Laboratoire d'Electrochimie et de Chimie Analytique, Ecole Nationale Supérieure de Chimie de Paris, France.
According to Stokes' treatment, the ionic mobility of particles, which are small with respect to Debye length, is usually considered to be proportional to the nominal charge and inversely proportional to the hydrodynamic radius. Experimentally, it is well known, however, that the ionic mobility of a small multicharged molecule does not depend linearly on its nominal charge in a wide range. This behavior can be accounted for by a condensation of the charge or a modification of the friction coefficient with the charge.
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