Fig 6.

Variability of endogenous GFP fluorescence among live F₂ individuals. Eggs from a single ROSA26 transgenic female (F₁) were fertilized in vitro using wild-type sperm. Qualitative were recorded among the resulting F₂ progeny viewed under identical conditions (constant time and intensity of exposure to UV illumination). These individuals were assigned among four groups according to qualitative measures of GFP fluorescence: brightest (B; +++), intermediate (D; ++), low (F; +) and undetectable (H; −). The last group is indistinguishable from wild-type individuals (J). There was no apparent difference in morphology among F₂ individuals, nor between transgenic and wild-type individuals. The 3 : 1 ratio of GFP-expressing (B,D,F; n = 147) to non-GFP-expressing individuals (H; n = 48) suggests that the F₁ female assayed in this experiment probably carries multiple copies of the ROSA26:GFP transgene. Scale bar, 1 mm.