Darwin was not aware of reporter genes. Sometimes you broke your head in engineering, designing, conceptualizing the perfect molecular assay to monitor a biological process. You ask yourself whether a genetically-based approach would be better than a probe-based approach with fluorophores or whatever. You are so trapped in your commitment to hack the original system with that smart molecular sensor, that you miss to consider simplicity.
|from Flickr: (C) DEAN|
Bernhard Kräutler and co-workers at the University of Innsbruck in Austria, discovered that because of chlorophyll breakdown, there is a blue luminescence in ripening bananas under UV light. No molecular approaches to estimate the degree of ripening, just observation (at UV light). Interestingly, not all animals see in the same spectral range, and a fruit color determines which species can see it ripening (birds and insects can see ultraviolet light, primates cannot). Next time I'm going to the grocery, I'll bring the transilluminator.
Simone Moser, Thomas Müller, Marc-Olivier Ebert, Steffen Jockusch, Nicholas J. Turro, Bernhard Kräutler (2008). Blue Luminescence of Ripening Bananas Angewandte Chemie International Edition, 47 (46), 8954-8957 DOI: 10.1002/anie.200803189