Imaging

The rsCaMPARI technology is a groundbreaking sensor technology that provides a reversible method for marking and tracking neuronal activity. Based on photoconvertible fluorescent proteins, traditional neuronal activity markers offer permanent and irreversible marking, which limits their utility in experiments requiring multiple snapshots of activity within the same sample. To address this limitation, rsCaMPARI employs a reversibly switchable fluorescent protein (rsFP) that can photoswitch between bright and dim states in response to different wavelengths of light.

iATPSnFR2 is a circularly permuted GFP-based ATP sensor engineered for rapid, high-sensitivity detection of ATP levels in living cells. With ratiometric readout options and subcellular targeting flexibility, it's ideal for neuroscience, cell biology, and metabolism research, and drug screening.

In the world of neuroscience, particularly in Drosophila studies, researchers face a significant challenge in matching neuronal structures across different imaging modalities.

The GENIE Project Team at HHMI Janelia Research Campus have developed and characterized multiple transgenic mice expressing jGCaMP8s and jGCaMP8m (see https://doi.org/10.25378/janelia.24565837) and deposited the lines at The Jackson Laboratory (JAX).

Progress in neuroscience demands the ability to record electrical activity optically in specifically tagged neurons in behaving animals. With that in mind, GENIE Project's accomplished researchers harnessed their skills in assay and reagent development to create a superior, persistently visible genetically encoded voltage indicator (GEVI).

Voltron 2.0 and Positron 2.0 are state-of-the-art genetically encoded voltage indicators (GEVIs) for use in vivo or in vitro. Developed and optimized at Janelia for sensitivity, signal strength, and speed, they couple to Janelia Fluor® dyes via the HaloTag protein labeling system. 

iGABASnFR2 is the current (2022) generation of GABA-Sensing Fluorescent Reporters developed at HHMI's Janelia Research Campus. Other sensor technologies such as SF-iGluSnFR, jGCaMP8, and jRGECO are optimized for excitatory synaptic transmission and action potentials.

iGluSnFR3 is the current (2022) generation of Glutamate-Sensing Fluorescent Reporters developed at HHMI's Janelia Research Campus to image the most abundant neurotransmitter in the mammal brain with the greatest performance to date. 

Fig 1. iGluSnFR mechanism of action

Performance

Selective Plane Illumination Microscopy (SPIM) is a powerful tool for volumetric imaging of cleared specimens. The Zeiss Lightsheet microscope Z.1 offers a commercial solution for SPIM imaging. The Z.1 presents sample mounting challenges, though. For example, users must position samples vertically and stabilize them for hours-long imaging sessions. Therefore, we offer custom sample holder designs to mount cleared and expansion microscopy (ExM) samples on the Z.1 system.

The correct positioning of optical elements like lenses, mirrors, and AOTFs in optical systems can often be tedious. However, precise and reproducible alignment tools can simplify the positioning of optical elements tremendously.