Vermaas said the researchers employed an advanced image analysis method that was developed at Sandia Labs.
This is an analysis method that is superior to what commercial analysis systems can do. It tells you where the fluorescent materials are in the cell, what the fluorescence of each material looks like and how much is present even if the fluorescence properties look like each other, said Vermaas, who is a member of ASUs Center for Bioenergy and Photosynthesis.
Vermaas said the initial study focused on localization of pigments in a cyanobacterium, a specific type of bacteria of interest to the team. With the method, they showed that photosynthesis-related pigments (chlorophylls, phycobilins and carotenoids) can be localized in vivo in cells of the cyanobacterium Synechocystis sp. PCC 6803 through deconvolution of individual fluorescence emission spectra in small (0.03 cubic micrometer) volumes by means of hyperspectral confocal fluorescence imaging.
The method allows us to push the resolution limits of confocal fluorescence microscopy, particularly when there are mixtures of different fluorescent compounds with relatively similar spectra, Vermaas explained. In the specific case of cyanobacteria, it enables the detection of different pigments relative to each other in the cell, and we were able to localize the two different photosystems in the cell relative to each other, along with other pigments.
Using the technique, the researchers report that results obtained indicate a heterogeneous composition of thylakoid membranes in cyanobacteria: Phycobilin emission was most intense along the periphery of the cell whereas chlorophyll fluorescence was distributed more evenly throughout the cell, suggesting that fluorescing phycobilisomes are more prevalent along the outer thylakoids. Carotenoids were prevalent in the cell wall and also were present i
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Arizona State University