Calcium Imaging: A Method to Visualize Neural Activity in Live C. elegans

Published: April 30, 2023

Abstract

Source: Turek, M. et al. Agarose Microchambers for Long-term Calcium Imaging of Caenorhabditis elegans. J. Vis. Exp. (2015).

This video introduces the concepts behind calcium imaging and includes an example protocol for time-lapse imaging of worms contained in molded agarose wells.

Protocol

This protocol is an excerpt from Turek et al, Agarose Microchambers for Long-term Calcium Imaging of Caenorhabditis elegansJ. Vis. Exp. (2015).

1. Calcium Imaging

  1. Use transgenic strains expressing genetically encoded calcium sensors such as HBR16 (goeIs5[pnmr-1::SL1-GCaMP3.35-SL2::unc-54-3'UTR, unc-119(+)]).
  2. Use a compound microscope equipped for wide-field epifluorescence. Connect the TTL output of the EMCCD camera to the TTL input of the LED, so that each time the camera records a frame the sample will be illuminated. Use an exposure time of about 5 msec. Use EM gain in the range of 50 – 300.
  3. Specify a burst movie running for 24 hr with each worm being imaged every 15 – 30 min first for 20 sec with DIC, then for 20 sec with a GFP fluorescence to record GCaMP, and then take a final image of the mKate2 signal is taken to control for expression levels. Use a frame rate of 2/sec during each burst.
  4. For visual data inspection, use a false-color map to enhance the visibility of small changes in fluorescence intensity. Plot fluorescent data as ΔF/F, with F being the average baseline value of fluorescence. A detailed description of calcium data analysis can be found in the literature.

Materials

LED system CoolLED pE-2
Compound microscope Nikon TiE
EMCCD camera Andor iXon 897 now sold as iXon Ultra 897
Z-stage for the microscope Prior Nano Scan Z
X-Y stage for the microscope Prior Proscan III
Red light filter Chroma ET660/50m
35 mm Petri dish Falcon Falcon Disposable Petri Dishes, Sterile, Corning

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Cite This Article
Calcium Imaging: A Method to Visualize Neural Activity in Live C. elegans. J. Vis. Exp. (Pending Publication), e20164, doi: (2023).

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