Biology Reference
In-Depth Information
ng/ul and 100 ng/ul onto pollen tube guidance assay plates. Time-lapse imaging
was performed as described for in vitro pollen tube behaviours except that images
were captured once in 30 minutes. The rates of diffusion (3 kD = 5.5
µ
m/min;
10 kD = 2.73
µ
m/min; 40 kD = 2.43
µ
m/min and 70 kD = 1.01
µ
m/min) were
measured from these images using ImageJ software. Specifically, the fluorescent
intensities along a line drawn from the centre of a dextran spot to the diffused
periphery were calculated for an entire time-lapse series. The data was imported
into Microsoft Excel and regression analyses were performed. Extrapolating from
these values, molecular weights were estimated for attractants that would diffuse
33
µ
m and repellents that would diffuse 27
µ
m in 300 minutes (the time required
for a typical pollen tube to reach an ovule in the in vitro assay).
Statistical Analysis
To measure the significance of the differences among observed ovule targeting
efficiencies, we employed a
χ
2 test for consistency in observed frequency distribu-
tions with a dichotomous classification and variable sample size [38].
Authors' Contributions
RP carried out experiments described in this study. RP and DP conceived, de-
signed, coordinated this study and drafted the manuscript. Both authors read and
approved the final manuscript.
Acknowledgements
We thank M Johnson, A Hall and E Updegraff for helpful suggestions; N Hage-
mann for Lat52:GFP transgenic plants; MJ Root, S Bond and A Young for tech-
nical assistance; J Yang and J Lui for assistance with statistical analysis. Funding
was provided by the Department of Energy DE-FG02-96ER20240 and the Uni-
versity of Chicago MRSEC (NSF DMR-0213745).
References
1. Weterings K, Russell SD: Experimental analysis of the fertilization process. Plant
Cell 2004, 16 Suppl:S107-18.
2. Lord EM, Russell SD: The mechanisms of pollination and fertilization in plants.
Annu Rev Cell Dev Biol 2002, 18:81-105.
