Astrocyte-Specific Inhibition of the Primary Cilium Suppresses C3 Expression in Reactive Astrocyte.

C3-positive reactive astrocytes play a neurotoxic role in various neurodegenerative diseases. However, the mechanisms controlling C3-positive reactive astrocyte induction are largely unknown. We found that the length of the primary cilium, a cellular organelle that receives extracellular signals was increased in C3-positive reactive astrocytes, and the loss or shortening of primary cilium decreased the count of C3-positive reactive astrocytes. Pharmacological experiments suggested that Ca2+ signalling may synergistically promote C3 expression in reactive astrocytes. Conditional knockout (cKO) mice that specifically inhibit primary cilium formation in astrocytes upon drug stimulation exhibited a reduction in the proportions of C3-positive reactive astrocytes and apoptotic cells in the brain even after the injection of lipopolysaccharide (LPS). Additionally, the novel object recognition (NOR) score observed in the cKO mice was higher than that observed in the neuroinflammation model mice. These results suggest that the primary cilium in astrocytes positively regulates C3 expression. We propose that regulating astrocyte-specific primary cilium signalling may be a novel strategy for the suppression of neuroinflammation.

Spatiotemporal observation of light propagation in a three-dimensional scattering medium.

Spatiotemporal information about light pulse propagation obtained with femtosecond temporal resolution plays an important role in understanding transient phenomena and light-matter interactions. Although ultrafast optical imaging techniques have been developed, it is still difficult to capture light pulse propagation spatiotemporally. Furthermore, imaging through a three-dimensional (3-D) scattering medium is a longstanding challenge due to the optical scattering caused by the interaction between light pulse and a 3-D scattering medium. Here, we propose a technique for ultrafast optical imaging of light pulses propagating inside a 3D scattering medium. We record an image of the light pulse propagation using the ultrashort light pulse even when the interaction between light pulse and a 3-D scattering medium causes the optical scattering. We demonstrated our proposed technique by recording converging, refracted, and diffracted propagating light for 59 ps with femtosecond temporal resolution.

Single-shot femtosecond-pulsed phase-shifting digital holography.

Parallel phase-shifting digital holography is capable of three-dimensional measurement of a dynamically moving object with a single-shot recording. In this letter, we demonstrated a parallel phase-shifting digital holography using a single femtosecond light pulse whose central wavelength and temporal duration were 800 nm and 96 fs, respectively. As an object, we set spark discharge in atmospheric pressure air induced by applying a high voltage to between two electrodes. The instantaneous change in phase caused by the spark discharge was clearly reconstructed. The reconstructed phase image shows the change of refractive index of air was -3.7 × 10(-4).