All-optical presynaptic plasticity induction by photoactivated adenylyl cyclase targeted to axon terminals

Intracellular signaling plays essential roles in various cell types. In the central nervous system, signaling cascades are strictly regulated in a spatiotemporally specific manner to govern brain function; for example, presynaptic cyclic adenosine monophosphate (cAMP) can enhance the probability of neurotransmitter release. In the last decade, channelrhodopsin-2 has been engineered for subcellular targeting using localization tags, but optogenetic tools for intracellular signaling are not well developed. Therefore, we engineered a selective presynaptic fusion tag for photoactivated adenylyl cyclase (bPAC-Syn1a) and found its high localization at presynaptic terminals. Furthermore, an all-optical electrophysiological method revealed rapid and robust short-term potentiation by bPAC-Syn1a at brain stem-amygdala synapses in acute brain slices. Additionally, bPAC-Syn1a modulated mouse immobility behavior. These results indicate that bPAC-Syn1a can manipulate presynaptic cAMP signaling in vitro and in vivo. The all-optical manipulation technique developed in this study can help further elucidate the dynamic regulation of various cellular functions.

All-Optical Manipulation of Magnetization in Ferromagnetic Thin Films Enhanced by Plasmonic Resonances

In this paper, we report all-optical manipulation of magnetization in ferromagnetic Co/Pt thin films enhanced by plasmonic resonances. By annealing a thin Au layer, we fabricate large-area Au nanoislands on top of the Co/Pt magnetic thin films, which show plasmonic resonances around the wavelength of 606 nm. Using a customized magneto-optical Kerr effect setup, we experimentally observe an 18.5% decrease in the minimum laser power required to manipulate the magnetization, comparing the on- and off-resonance conditions. The results are in very good agreement with numerical simulations. Our research findings demonstrate the possibility to achieve an all-optical magnetic recording with low energy consumption, low cost, and high areal density by integrating plasmonic nanostructures with magnetic media.