西亚试剂：：DNA walk

DNA walk

A DNA walk of a genome represents how the frequency of each nucleotide of a pairing nucleotide couple changes locally. This analysis implies measurement of the local distribution of Gs in the content of GC and of Ts in the content of TA. Lobry was the first to propose this analysis (1996, 1999). Two complementary representations can be derived from the DNA walk: the cumulative TA- and the GC-skew analysis.

Aim: By reading these description of the algorithm, a reader not trained in genomics is able to redraw our graphs, using the basic genometric data file that is posted on our web resource for each organism as a zip file (.zip).

 DNA walk

1) Drawing a DNA walk by reading a sequence file nucleotide by nucleotide.

A simple algorithm is used to draw a DNA walk by simply assigning a direction to each nucleotide. We propose the following assignment, slightly different from Lobry's: to T, C, A, and G correspond the E(ast), S(outh), W(est), and N(orth) directions, respectively (Lobry, 1999). Reading the nucleotide sequence nucleotide by nucleotide, and following the rule, a path clearly emerges on the graph: Figure 1.

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