Research Paper Volume 5, Issue 11 pp 813—824

Figure 2. Age-related loss of gene silencing in heterochromatin regions. Percent of HS-lacZ expressing cells increases with age in oenocytes (A, C) and Malpighian tubules (B, D) in BL1 and BL2 PEV lines, and in thoracic bristle roots in BL2 (E) (Black solid bars heat shocked=HS+). Three independent biological replicates from three separate cohorts were collected and examined for each age; a minumum of 15 flies per time point represent at least 75 flies (≥ 8,250 cells) total for oenocytes, and at least 30 flies (≥ 11,400 cells) total for Malpighian tubules. White open bars are the percent of HS-lacZ expressing cells without heat shock (HS-). BL1 Malpighian tubules were examined in only two separate biological replicates of 10 flies each. Without heat shock there is no lacZ expression in the BL1 oenocytes or in the thoracic bristle roots for BL1 and BL2 at age day 10 and day 50. Error bars represent SD, *P <0.05; **P < 0.01; and ***P<0.001. Neither BL1 nor BL2 show a non-heat shock, age-related increase of lacZ in flight or leg muscles as seen in euchromatin HS-lacZ reporters [40].