Cover image

Cover A conceptual representation of the targeted integration of yeast retrotransposon Ty1 upstream of tRNA genes in the yeast genome. Integration peaks were periodic (represented by the concentric rings around the DNA and the curves in the background), and separated by ~80 bases. Analysis of 836 de novo genomic Ty1 integration events revealed several specific target site preferences that were based on the presence of surrounding genetic features. Ty1 preferred specific tRNA targets to identical copies in other locations, and concentric rings on chromosomes represent preferred tRNA gene targets in the t^Gly and t^Thr gene families and their genomic positions. Single circles represent least preferred or "cold" targets. Schematic in upper right shows genomic features surrounding the most preferred target tRNA gene (above), which contained the target tRNA gene (dark arrow), a neighboring tRNA gene (light arrow), and several Ty1 LTRs (long triangles). In contrast, the "cold" target (below) contained the target tRNA gene (dark arrow) with no surrounding features. Adding the surrounding features to the "cold" target increased Ty1 integration frequency upstream. (Cover illustration by Bang Wong, ClearScience/ www.clearscience.info. [for details, see Bachman et al, pp. pp.1232–1247.])