Fig. 1. Transgene expression, histone modification and morphology in germ cells. (A,B) Differential interference contrast (top panels) and GFP fluorescence (bottom panels) microscopy of hermaphrodite ovaries from transgenic line PD7271, which carries an extrachromosomal, multi-copy array of a let-858:gfp reporter transgene, pBK48.1 (A), and line KW1336, which carries an extrachromosomal ‘complex’ array with pBK48.1 (B). Brackets indicate germ cell nuclei in one hermaphrodite ovary arm. The arrowheads in the lower panels illustrate GFP fluorescence in intestinal cell nuclei. The lower panel in A represents a longer exposure than that shown in B to demonstrate a complete lack of detectable nuclear GFP expression in germ cells in this transgenic line (brackets; the few fluorescent nuclei within the brackets are from somatic components of the gonad). (C,D) Paraformaldehyde-fixed oocytes from PD7271 (C) and KW1336 (D) hermaphrodites were stained with -H3 dimethyl-K4 antibody (green) and counterstained with DAPI (red), arrowheads indicate transgene arrays. (E,F) Paraformaldehyde-fixed pachytene stage nuclei from transgenic PD7271 hermaphrodites (E) and N2 males (F) were stained with DAPI and examined by deconvolution fluorescence microscopy. Au, autosomes; X, X chromosome; Tgn, transgene, Scale bars: 5 µm in C-F.