PT  - JOURNAL ARTICLE
AU  - Dmitrijs Celinskis
AU  - Nina Friedman
AU  - Mikhail Koksharov
AU  - Jeremy Murphy
AU  - Manuel Gomez-Ramirez
AU  - David Borton
AU  - Nathan Shaner
AU  - Ute Hochgeschwender
AU  - Diane Lipscombe
AU  - Christopher Moore
TI  - Miniaturized Devices for Bioluminescence Imaging in Freely Behaving Animals
AID  - 10.1101/2020.06.15.152546
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.06.15.152546
4099  - http://biorxiv.org/content/early/2020/06/16/2020.06.15.152546.short
4100  - http://biorxiv.org/content/early/2020/06/16/2020.06.15.152546.full
AB  - Fluorescence miniature microscopy in vivo has recently proven a major advance, enabling cellular imaging in freely behaving animals. However, fluorescence imaging suffers from autofluorescence, phototoxicity, photobleaching and non-homogeneous illumination artifacts. These factors limit the quality and time course of data collection. Bioluminescence provides an alternative kind of activity-dependent light indicator. Bioluminescent calcium indicators do not require light input, instead generating photons through chemiluminescence. As such, limitations inherent to the requirement for light presentation are eliminated. Further, bioluminescent indicators also do not require excitation light optics: the removal of this component should make lighter and lower cost microscope with fewer assembly parts. While there has been significant recent progress in making brighter and faster bioluminescence indicators, parallel advances in imaging hardware have not yet been realized. A hardware challenge is that despite potentially higher signal-to-noise of bioluminescence, the signal strength is lower than that of fluorescence. An open question we address in this report is whether fluorescent miniature microscopes can be rendered sensitive enough to detect bioluminescence. We demonstrate this possibility in vitro and in vivo by implementing optimizations of the UCLA fluorescent miniscope. These optimizations yielded a miniscope (BLmini) which is 22% lighter in weight, has 45% fewer components, is up to 58% less expensive, offers up to 15 times stronger signal (as dichroic filtering is not required) and is sensitive enough to capture spatiotemporal dynamics of bioluminescence in the brain with a signal-to-noise ratio of 34 dB.Competing Interest StatementThe authors have declared no competing interest.