title: Forward-filling of dextran-conjugated indicators for calcium imaging at the Drosophila larval neuromuscular junction.
abstract: Calcium imaging is a technique in which Ca(2+)-binding molecules are loaded into live cells and as they bind Ca(2+) they "indicate" the concentration of free calcium through a change in either the intensity or the wavelength of light emitted (fluorescence or bioluminescence). There are several possible methods for loading synthetic Ca(2+) indicators into subcellular compartments, including topical application of membrane-permeant Ca(2+) indicators, forward-filling of dextran conjugates, and direct injection. Calcium imaging is a highly informative technique in neurobiology because Ca(2+) is involved in many neuronal signaling pathways and serves as the trigger for neurotransmitter release. This article describes the forward-filling of dextran-conjugated indicators at the Drosophila larval neuromuscular junction (NMJ). This technique is particularly well suited for imaging changes in cytosolic Ca(2+) as dextran conjugation prevents compartmentalization of the Ca(2+) indicator. The major drawback is that the nerves must be severed at the start of the loading process, several hours before nerve terminals are ready to examine.
authors: Gregory T
authors: GT
authors: Macleod
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis*; D003600:Cytosol / Q000737:chemistry; D003911:Dextrans / Q000378:metabolism; D004330:Drosophila / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007202:Indicators and Reagents; D007814:Larva / Q000737:chemistry; D009446:Neurobiology / Q000379:methods*; D009469:Neuromuscular Junction / Q000737:chemistry*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D002118:Calcium