I am working on the expression of GFP-fusions in mouse oocytes. In one
case I was able to target a fusion to the meiotic spindle, which
reflects the natural behaviour. However, control oocytes, expressing
EGFP only, beside a bright cytoplasm showed a faint staining of the
spindle, too. To make it even more puzzling, the condensed meiotic
chromosomes also showed a relatively bright signal (the chromosomes
haven´t been stained in these experiments). Fixation has been done with
methanol for 8 minutes. I have never observed chromosomes positive for
EGFP in living cells. Has anyone observed a similar behaviour of EGFP,
or might this be an effect of fixation conditions?
Thanks in advance, Matthias.
P.S.: Detection of EGFP was done with a single band EGFP filter set.