MPE imaging has significant advantages in thick, live samples. The image at right shows meiosis in an intact bud from petunia (yellow - DAPI; green - Rhodamine 123). The meiotic pollen forming cells at center typically have a high concentration of RH123 staining mitochondria. Image was taken at a depth of 180 µm in an excised bud. In collaboration with C. Conley and M. Hanson at Cornell University, we followed meiosis in both control and male sterile plants.

GFP, targeted to plastids, has revealed thin connections between them. Using MPE photobleaching, individual GFP containing plastids can be bleached. GFP freely diffuses between connected plastids as shown in the photobleaching experiment above. GFP fluorescence in the plastid was photobleached (arrow, a) and recovers as fresh GFP moves in from a connected plastid (b), demonstrating that proteins can pass between connected organelles. The recovery curve is shown above. MPE photobleaching eliminates the possibility of tissue photodamage outside of the focal plane, a property which is useful in ablation experiments as well. This research was carried out with R. Kohler and M. Hanson at Cornell as part of a study in plant male sterility. Transfected plants with mitochondrially targeted GFP were also created (Kohler,1997) and were used to follow the movements of mitochondria during meiosis.

W. Denk, J.H. Strickler and W.W. Webb. Science, 248:73, 1990.

R.M. Williams, D.W. Piston and W.W. Webb. FASEB J., 8:804, 1994.

W. Denk, D.W. Piston and W.W. Webb. in Handbook of Biological Confocal Microscopy (J. Pawley, ed.), p.445, 1995.

R. Kohler, W.R. Zipfel, W.W. Webb and M.R. Hanson. The Plant Journal.

Rainer H. Kohler, Jun Cao, Warren R. Zipfel, Watt W. Webb and Maureen R. Hanson, "Exchange of protein molecules through connections between higher plant plastids," Science 276, pp. 2039-2042 (27 June 1997).

C. Xu and W.W. Webb. in Topics in Fluorescence Spectroscopy (J.R. Lakowicz, ed.).