Figure 2: Establishing a platform for quantifying the amplitude of hb transcription.

(a) Shown are the mean profiles (with s.d. shown) of un-normalized hb mRNA FISH intensities (in a.u.’s) from embryos that have one, two or four copies of the hb gene. The mean and s.d. of x_hb expressed as fractional embryo length are: 0.435±0.013, 0.445±0.013 and 0.454±0.019 for 1 × , 2 × and 4 × hb embryos, respectively (n=16, 20 and 17). These results show that x_hb remains largely insensitive to changes in hb copy number in our experimental system; a relatively minor shift might be related to the limitations inherent to experimental detections³⁵. (b) Shown are hb_plat values (in a.u.’s) in individual embryos with different copies of the hb gene. The mean and s.d. are also shown in the figure (n=16, 20 and 17 for 1 × , 2 × and 4 × hb embryos, respectively). The linear fit between hb_plat and hb gene copy number is shown as a red line in the figure. (c) Shown are the mean profiles of un-normalized hb mRNA FISH intensities in embryos from mothers with one, two or three copies of bcd. The mean and s.d. of x_hb expressed as fractional EL are: 0.373±0.013, 0.446±0.009 and 0.510±0.010 for 1 × , 2 × and 3 × bcd embryos, respectively (n=11, 9 and 13). (d) Shown are hb_plat values in individual embryos from mothers with different copies of bcd. The mean and s.d. of hb_plat are: 23.93±6.75, 24.51±5.13 and 24.94±4.42 for 1 × , 2 × and 3 × bcd embryos, respectively (n=11, 9 and 13). P-values (obtained from Student’s t-tests and shown in the figure) reveal no significant differences.