Calcium imaging

Calcium imaging

Calcium imaging is a scientific technique usually carried out in research which is designed to show the calcium (Ca2+) status of a tissue or medium. Calcium imaging techniques take advantage of so called calcium indicators, molecules that can respond to the binding of Ca2+ ions by changing their spectral properties.Two main classes of calcium indicators exist: chemical indicators and genetically encoded indicators (GECI).

Chemical indicators

Chemical indicators are small molecules that can chelate calcium ions. All these molecules are based on an EGTA homologue called BAPTA, with high selectivity for calcium (Ca2+) ions versus magnesium (Mg2+) ions.

These group of indicators includes fura-2, indo-1, fluo-3, Calcium Green-1.

These dyes are generally used with the chelator carboxyl groups masked as acetoxymethyl esters, in order to render the molecule lipophilic and to allow easy entrance into the cell. Once the indicator is in the cell, cellular esterases will free the carboxyl and the indicator will be able to bind calcium.

Genetically encoded indicator

These indicators are fluorescent proteins derived from green fluorescent protein (GFP) or its variants (e.g. circularly permuted GFP, YFP, CFP), fused with calmodulin (CaM) and the M13 domain of the myosin light chain kinase, which is able to bind CaM.

Genetically encoded indicators do not need to be loaded onto cells, instead the genes encoding for these proteins can be easily transfected to cell lines. Is it also possible to create transgenic animals expressing the dye in all cells or selectively in certain cellular subtypes.

Examples of genetically encoded indicators are Pericams and Cameleons.

Usage

Regardless of the type of indicator used the imaging procedure is generally very similar.The spectral properties of the dye change upon binding to calcium. For example the dye could be fluorescent only after binding to calcium, or its excitation and emission spectra could be modified by the binding. Cells loaded with the indicator or expressing it in case of GECI, can be viewed using a fluorescence microscope, captured by a CCD camera and analyzed according to intensity, ultimately reflecting the Ca2+ status.

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Calcium concentration microdomains — Calcium microdomains are small aggregates, microdomains, of calcium channels located in presynaptic terminals. They are used to create a small area of high calcium concentration to activate various calcium dependent proteins within the… …   Wikipedia

  • Biological imaging — may refer to any imaging technique used in biology.Typical examples include: * Bioluminescence imaging, a technique for studying laboratory animals using luminescent protein * Calcium imaging, determining the calcium status of a tissue using… …   Wikipedia

  • Magnetic resonance imaging — MRI redirects here. For other meanings of MRI or Mri, see MRI (disambiguation). Magnetic resonance imaging Intervention Sagittal MR image of the knee ICD 10 PCS B?3?ZZZ …   Wikipedia

  • Chemical imaging — (as quantitative chemical mapping) is the analytical capability to create a visual image of components distribution from simultaneous measurement of spectra and spatial, time informations.[1][2] The main idea for chemical imaging, the analyst may …   Wikipedia

  • ratio-imaging fluorescence microscopy — A method of measurement of intracellular pH or intracellular calcium levels, using a fluorescent probe molecule (see fura 2), in which the two different excitation wavelengths are used, and the emitted light levels compared. If emission at one… …   Dictionary of molecular biology

  • Dendritic spine — Spiny dendrite of a striatal medium spiny neuron. Common types of dendri …   Wikipedia

  • Olfaction — Human olfactory system. 1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus (olfaction) 6: Olfactory receptor cells Olfaction (also known as olfactics; adjectival form: olfactory ) is the sense of smell. This sense is… …   Wikipedia

  • Fura-2 — Chembox new Name = Fura 2 ImageFile = Fura 2.png ImageSize = 200px ImageName = Fura 2 Section1 = Chembox Identifiers CASNo = 113694 64 7 Section2 = Chembox Properties Formula = C29H22N3O145 MolarMass = 636.50 g/mol Fura 2 is a ratiometric… …   Wikipedia

  • Neurophysiology — (from Greek νεῦρον, neuron, nerve ; φύσις, physis, nature, origin ; and λογία, logia) is a part of physiology. Neurophysiology is the study of nervous system function. The primary tools of basic neurophysiological research include… …   Wikipedia

  • Outline of biophysics — The following outline is provided as an overview of and topical guide to biophysics: Biophysics – interdisciplinary science that uses the methods of physical science to study biological systems.[1] Contents 1 Nature of biophysics 1.1 Biophysics… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”