In vivo absorption spectra ofNeurospora crassa white collar photomutants

White collar (wc) mutants ofNeurospora crassa, which lack several responses to blue light, did not have altered absorption spectra when compared to a control strain. We conclude either that thewc mutants do not lack photoreceptor pigments or alternatively that the photoreceptors are present at levels too low to detect. The results show that carotenoids can be genetically reduced to a level at which they should not interfere with spectrophotometric attempts to detect the blue light receptors.