Paper
3 September 2009 Multi-fractal property of perchlorate reductase gene sequences and DNA photonics application to UV fluorescence detection on Mars-like surfaces
George Tremberger Jr., Eric Cheung, N. Gadura, Todd Holden, Raji Subramaniam, Regina Sullivan, Pat Schneider, Alex Flamholz, David H. Lieberman, Tak D. Cheung
Author Affiliations +
Abstract
The discovery of perchlorate on Mars raises the possibility of the existence of perchlorate reduction microbes on that planet. The perchlorate reductase gene sequence fractal dimensions of two Dechloromonas species were compared with five other sequences in the microbial dimethyl sulfoxide (DMSO) reductase family. A nucleotide sequence can be expressed as a numerical sequence where each nucleotide is assigned its proton number. The resulting numerical sequence can be investigated for its fractal dimension in terms of evolution and chemical properties for comparative studies. Analysis of the fractal dimensions for the DMSO reductase family supports phylogenetic analyses that show that the perchlorate reductase gene sequences are members of the same family. A sub-family with roughly the same nucleotide length emerges having the property that the gene fractal dimension is negatively correlated with the Shannon di-nucleotide entropy (R2 ~ 0.95, N =5). The gene sequence fractal dimension is found to be positively correlated with the neighbor joining distances reported in a published protein phylogeny tree (R2~ 0.92, N = 5). The multi-fractal property associated with these genes shows that perchlorate reductase has lower dimensionality as compared to the relatively higher dimensionality DNA-break repair genes Rec-A and Rad-A observed in the Dechloromonas aromatica and Deinococcus radiodurans genomes. The studied perchlorate gene sequences show a higher Shannon di-nucleotide entropy (~3.97 bits) relative to Dechloromonas aromatica DNA repair sequences (~3.87 bits Rec-A, ~3.92 bits Rad-A), suggesting that there are fewer constraints on nucleotide variety in the perchorlate sequences . These observations thus allow for the existence of perchlorate reducing microbes on Mars now or in the past. Timeresolved UV fluorescence study near the emission bands of nucleotide sequences could be used for bio-detection on Mars-like surfaces and the results may further constrain the proposed conjectures.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
George Tremberger Jr., Eric Cheung, N. Gadura, Todd Holden, Raji Subramaniam, Regina Sullivan, Pat Schneider, Alex Flamholz, David H. Lieberman, and Tak D. Cheung "Multi-fractal property of perchlorate reductase gene sequences and DNA photonics application to UV fluorescence detection on Mars-like surfaces", Proc. SPIE 7441, Instruments and Methods for Astrobiology and Planetary Missions XII, 74410G (3 September 2009); https://doi.org/10.1117/12.825819
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KEYWORDS
Fractal analysis

Image information entropy

Microorganisms

Mars

Ultraviolet radiation

Chemical analysis

Luminescence

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