Some Blue Light Responses

In recent years, a wealth of information on photolyase-mediated DNA repair and cryptochrome- and phototropin-mediated blue-light responses was obtained through the combined efforts of biologists, chemists, and physicists, from both experimental and theoretical studies. Here we have chosen recent examples of experimental work from our group to demonstrate the potential of modem EPR methods to answer mechanism-related questions and to study reactive intermediates in photo-induced electron transfer. Nevertheless, some key questions of these reactions remain to be solved. Important questions are as follows. What are the precise differences between CPD photolyase and (6 ) photolyase regarding... 

This brief chapter on action spectroscopy has given some practical methodology for obtaining action spectra from fluence-response data. Special mention was made of applications in the field of blue-Hght effects, in which action spectroscopy remains particularly active, mainly because, in most organisms with blue-light response, the responsible pigments remain to be isolated and identified. 

First, zooplankton may adapt or alter their seasonal or spatial distribution to reduce the UV-stress. Seasonal life cycle adaptations to avoid periods of peak solar intensity may very well be a strategy for UV-exposed and sensitive organisms, yet this is not explicitly demonstrated. Diurnal vertical migration is, however, commonly accredited to direct UVR [8,9]. A critical question is whether organisms have a sufficient spectral resolution to separate UVR from, for example, blue light. This may be important to respond to an increased UVR under constant PAR. Such behavioral responses clearly are important evolutionary traits for swimming animals, and could affect both productivity and trophic interactions the topic will be fully covered in another chapter, and will thus only briefly be touched upon here to illustrate some ecological implications. 

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