GUIDING LIGHTS: Channelrhodopsins from algae such as Guillardia theta (center; false-color image) are endowing optogenetics with novel abilities.DR DAVID HILLThe paper
E.G. Govorunova et al., “Natural light-gated anion channels: A family of microbial rhodopsins for advanced optogenetics,” Science, doi:10.1126/science.aaa7484, 2015.

Channel Surfing
Channelrhodopsins (ChRs) from green algae paved the way for optogenetics research in neuroscience and other fields. These membrane ion transporters are light sensitive, and importing them into neurons has given scientists unprecedented control over neuronal activity. The 50 or so known algal ChRs only transport positive ions, however, which trigger action potentials. Only one ChR from an Archean species and engineered algal ChRs can transport anions, which suppress neuronal firing by hyperpolarizing neurons, and neither is as fast or sensitive as the natural algal channels. “[ChRs] enabled fairly efficient activation of neurons, but neural inhibition was limited to much lower-efficiency tools,”...

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