Optimizing Calcium Detection Methods in Animal Systems: A Sandbox for Synthetic Biology

Abstract

Since the 1970s, the emergence and expansion of novel methods for calcium ion (Ca2+) detection have found diverse applications in vitro and in vivo across a series of model animal systems. Matched with advances in fluorescence imaging techniques, the improvements in the functional range and stability of various calcium indicators have significantly enhanced more accurate study of intracellular Ca2+ dynamics and its effects on cell signaling, growth, differentiation, and regulation. Nonetheless, the current limitations broadly presented by organic calcium dyes, genetically encoded calcium indicators, and calcium-responsive nanoparticles suggest a potential path toward more rapid optimization by taking advantage of a synthetic biology approach. This engineering-oriented discipline applies principles of modularity and standardization to redesign and interrogate endogenous biological systems. This review will elucidate how novel synthetic biology technologies constructed for eukaryotic systems can offer a promising toolkit for interfacing with calcium signaling and overcoming barriers in order to accelerate the process of Ca2+ detection optimization.

Fiber-based lactate recordings with fluorescence resonance energy transfer sensors by applying an magnetic resonance-informed correction of hemodynamic artifacts

“…However, this was not the case for our study since the fluorescence signals had slow dynamics in all experiments. The half decay time of Twitch-2B is 2.8 s. 67 Further, the response of cerebral lactate to electrical stimulation is on the timescale of seconds, 14 , 15 and finally, a very slow but constant signal change is expected for phFRET upon a 3-min injection. For other fluorescence recordings with fast kinetics (e.g., calcium imaging with GCaMP6f 68 ), line scanning MRI could be used for correction, enabling temporal resolutions of 50 ms. 69 , 70 …”

Encoding, transmission, decoding, and specificity of calcium signals in plants

“…Single-wavelength indicators include Oregon Green 488 BAPTA-1, and Fluo-4 and Fluo-5 acetoxymethyl ester and pentapotassium, each containing a fluorophore and calcium chelator, with increased dynamic range for qualitative analysis ( Kanchiswamy et al , 2014 ; Lock et al , 2015 ). Limitations include variability in determining intracellular calcium levels as a consequence of dye extrusion, uneven loading, dye retention, photobleaching, and cell toxic side effects ( Gasterstädt et al , 2020 ; Li and Saha, 2021 ). Ratiometric or dual-wavelength dyes are UV-excitable, and quantitatively detect fluctuations in target ion concentrations.…”

Genetically encoded fluorescent biosensors for GPCR research

“…This interaction was also applied to design the first cpFP-based Ca 2+ sensors GCaMP ( Nakai et al, 2001 ), which has been continuously improved for better sensitivity, brightness, stability, signal-to-noise ratio ( Chen et al, 2013 ; Dana et al, 2019 ), and different colors ( Zhao et al, 2011 ; Inoue et al, 2019b ; Qian et al, 2019 ). Excellent reviews for the Ca 2+ sensors are available ( Kerruth et al, 2019 ; Li and Saha, 2021 ; Lohr et al, 2021 ).…”