Biomedical Engineering Reference
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Drosophila flies that permitted the expression of TN-XL (for X-large) under the control of an
upstream activation sequence (UAS) ( Brand and Perrimon, 1993 ). They did this to analyze
the exhibited changes of TN-XL in neurons of living animals. These authors noted that electric
stimulation of the nerve harboring the innervating axon evoked reliable fluorescent changes.
Figure 9.7a shows the binding and the dissociation phases for the 1.5 mM calcium
FRET-
based calcium biosensor employing troponin C ( Mank et al., 2006 ). The external stimulation
frequency was 160 Hz for 2.2 s. A dual-fractal analysis is required to adequately describe the
kinetics in the binding phase. A single-fractal analysis is adequate to describe the kinetics in
the dissociation phase. The values of (a) the binding rate coefficient, k , and the fractal dimen-
sion, D f , for a single-fractal analysis, (b) the binding rate coefficients, k 1 and k 2 , and the fractal
dimensions, D f1 and D f2 , for a dual-fractal analysis, and (c) the dissociation rate coefficient, k d ,
and the fractal dimension, D fd , in the dissociation phase are given in Tables 9.7 and 9.8 .
þ
60
35
30
50
25
40
20
30
15
20
10
10
5
0
0
0
0.5
1
1.5
2
2.5
3
0
0.5
1
1.5
2
2.5
3
A
B
Time (s)
Time (s)
12
80
10
60
8
40
6
4
20
2
0
0
0
0.5
1
1.5
2
2.5
3
0
0.5
1
1.5
2
2.5
3
D
Figure 9.7
Time (s)
C
Time (s)
Binding and dissociation of calcium
FRET-based calcium biosensor employing troponin C ( Mank
et al., 2006 ). TN-XL fluorescence in Drosophila in vivo. 1.5 mM external calcium (a-c). Effect of
different external stimulation frequencies for 2.2 s. (a) 160 Hz (b) 80 Hz (c) 40 Hz (d) 160 Hz
þ
þ
10 mM external calcium. When only a solid line (--) is used then a single-fractal analysis applies.
When both a dashed (- - -) and a solid (--) line are used then the dashed line represents a single-
fractal analysis and the solid line represents a dual-fractal analysis.
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