Biology Reference
In-Depth Information
especially at low calcium concentration, so that a subset of smaller signals is
overlooked (
Rei
et al.
, 2005
).
In general, genetically encoded calcium sensors are not available commercially,
though
V
V
ers YC3.60 (
http://probes.invitrogen.com/media/pis/
mp36207.pdf
)
. Some can be obtained for noncommercial use from their creators
(
http://www.tsienlab.ucsd.edu/
and
http://cfds.brain.riken.jp/
)
. Or you can make
your own using the handbook (
Miyawaki
et al.
, 2003a, 2005
).
Invitrogen
o
V. Conclusions
Genetically encoded calcium sensors have proved valuable in the measurement
of calcium concentration in cellular organelles, for the most part in single cells
in vitro
. Their success as sensors in tissues
in vitro
and
in vivo
is qualified. They have
also proved valuable in imaging the pattern of calcium signals within tissues,
particularly in the poikilotherms,
C. elegans
,
Drosophila
, and zebrafish. In home-
otherms, the record is largely disappointing, even when tissue is excised and
monitored at room temperature (
Pologruto
et al.
, 2004
). Striking exceptions are
the use of GCaMP2 to image calcium-signaling patterns in mouse heart (
Tallini
et al.
, 2006
) and pyramidal neurones (Tian
et al
., 2009). For the most part, sensors
are still not capable of sensing individual calcium events in single cells when these
cells are part of tissue, though single cell responses can be monitored in disaggre-
gated cells (
Kotliko
, 2007
). Some branches of the calcium sensor evolutionary
tree continue to evolve rapidly and the steady progress in optimizing sensor
parameters leads to the certain hope that these drawbacks will eventually be
overcome by further genetic engineering.
V
Acknowledgments
I thank Jill McKenna for helping with this chapter. Our work is supported by grants from the
Wellcome Trust.
References
Akerboom, J., Rivera Jonathan, D. V., Guilbe Maria, M. R., Malave Elisa, C. A., Hernandez
Hector, H., Tian, L., Hires, S. A., Marvin Jonathan, S., Looger Loren, L., and Schreiter Eric, R.
(2009). Crystal structures of the GCaMP calcium sensor reveal the mechanism of fluorescence signal
change and aid rational design.
J. Biol. Chem. 284,
6455-6464.
Allen, G. J., Kwak, J. M., Chu, S. P., Llopis, J., Tsien, R. Y., Harper, J. F., and Schroeder, J. I. (1999).
Cameleon calcium indicator reports cytoplasmic calcium dynamics in Arabidopsis guard cells.
Plant
J. 19,
735-747.
Allen, G. J., Chu, S. P., Schumacher, K., Shimazaki, C. T., Vafeados, D., Kemper, A., Hawke, S. D.,
Tallman, G., Tsien, R. Y., Harper, J. F., Chory, J., and Schroeder, J. I. (2000). Alteration of stimulus-
specific guard cell calcium oscillations and stomatal closing in Arabidopsis det3 mutant.
Science 289,
2338-2342.
