Light is one of the most important signals providing critical information to biological systems. In addition to giving us visual input, light controls movement, growth, differentiation and development, circadian timing, and a host of gene-expression responses in diverse organisms from primitive unicellular microbes through higher plants and animals. The conference will focus on current research on photosensory receptors, covering their mechanisms of photoactivation and downstream elements of their signal transduction pathways. This area of research is a fast-moving one, and progress is being made on several long-standing fundamental questions: By what mechanisms is photon energy captured and stored in photoreceptor proteins? How is light color discriminated? How do photoactivated receptor proteins communicate their signals to the cell? Investigators who study photosensory receptors in very different systems (e.g. plants, animals, eukaryotic microbes, and prokaryotes) are confronting many of the same research challenges. However in recent years there has not been a dedicated meeting bringing together this group. Given the rapid advances currently being made, a Photosensory Receptors conference bringing together scientists studying photoreceptors and their immediately downstream signal transduction components is particularly appropriate. It will provide a very much-needed opportunity to exchange information and ideas and to become aware of some of the diverse tools available.

Several new classes of photosensory receptors have been discovered in the last few years. These include the flavoprotein cryptochromes in both plants and animals; the photoreceptor for phototropism, phototropin, in plants; retinal proteins homologous to archaeal rhodopsins in eukaryotic microbes, phytochromes in prokaryotes homologous to those in higher plants, and photoactive yellow proteins (PYPs) in photosynthetic bacteria. There are already genome projects that are clarifying their distribution in nature. Their mechanisms of activation and signal transduction are being unraveled at a rapid pace and we expect the conference will stimulate exciting discussion of emerging insights, general principles, and the most engaging mysteries on the cutting edge of photosensory signal transduction.