Non-Invasive Measurements of Photosystem II Reactions in the Field Using Flash Fluorescence

Author(s):  
Howard Robinson
Keyword(s):  
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.


Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.


2001 ◽  
Vol 120 (5) ◽  
pp. A266-A266
Author(s):  
R BUTLER ◽  
B ZACHARAKIS ◽  
D MOORE ◽  
K CRAWFORD ◽  
G DAVIDSON ◽  
...  

2001 ◽  
Vol 120 (5) ◽  
pp. A491-A491 ◽  
Author(s):  
A LEODOLTER ◽  
D VAIRA ◽  
F BAZZOLL ◽  
A HIRSCHL ◽  
F MEGRAUD ◽  
...  
Keyword(s):  

2020 ◽  
Vol 158 (6) ◽  
pp. S-1249
Author(s):  
Yuri Hanada ◽  
Juan Reyes Genere ◽  
Bryan Linn ◽  
Tiffany Mangels-Dick ◽  
Kenneth K. Wang

2007 ◽  
Vol 177 (4S) ◽  
pp. 430-430
Author(s):  
Ram Ganapathi ◽  
Troy R. Gianduzzo ◽  
Arul Mahadevan ◽  
Monish Aron ◽  
Lee E. Ponsky ◽  
...  

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