Figure 2. Locations of TEs Integrating into the Proximal Promoters of Hsp70 Genes.

Six nearly identical Hsp70 genes are present in the sequenced Drosophila genome, but only five copies in natural populations. The locations of selected promoter elements and sites are indicated for all copies.

(A) Previously discovered TEs and experimental transpositions relative to the conserved Hsp70 sequence. a, Jockey element in Hsp70Ba [16]; b, c, and d, P elements in Hsp70Ba [14,15,21]. An S element is present between the oppositely oriented paralogs Hsp70Aa and Hsp70Bb [13], and is represented twice, corresponding to its location relative to each paralog, as are the HMS Beagle (e) [16] and “56H8” (f) [88] elements inserted within it. Triangles below the line indicate transgene insertion sites (FlyBase; http://flybase.bio.indiana.edu). (B) and (C) Bottom: newly discovered TEs, with the natural population in which they were discovered (F01–F54, exclusive of F06) indicated for each.

(B) TEs other than P elements. Four are Gypsy elements that have integrated into the S element in specific populations, the fifth is a Gypsy that has inserted into a Gypsy, and the sixth is a Jockey that has inserted into a P element. The Gypsys are arbitrarily plotted relative to Hsp70Ab and Hsp70Aa, respectively.

(C) Natural P elements in Hsp70. The arrows indicating the number of independent EPgy2 insertion sites recently described by Shilova et al. [10]. Except for the Gypsys, TEs were not mapped to a specific Hsp70 gene. Insertion sites localized within the Hsp70 region were all established by sequencing. For population codes, see Figure 1.