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Tetrazolium reduction and nitrogenase activity in heterocystous blue-green algae

Tetrazolium reduction and nitrogenase activity in heterocystous blue-green algae 203 87 87 4 4 Peter Fay S. A. Kulasooriya Department of Botany, Westfield College University of London England Department of Botany University of Ceylon Peradeniya Ceylon Summary Heterocysts reduce triphenyl tetrazolium chloride (TTC) faster than vegetative cells apparently because the absence of the O 2 -evolving photosystem II and the high electron transport activity in these cells. Although the rate of TTC reduction in vegetative cells is increased by the continuous removal of O 2 evolved in photosynthesis, it has not been possible to obtain rates of TTC reduction comparable with those in heterocysts probably because of the continued competition for electrons between TTC and O 2 . The use of nitro-blue tetrazolium chloride (NBT) as a redox indicator has revealed the presence in filaments under aerobic conditions of a gradient of electron transport activity with strongest reducing power in the heterocysts, proheterocysts and vegetative cells next to heterocysts, and with gradually diminishing activity midway between two heterocysts. This pattern is indistinct in filaments grown under micro-aerophilic conditions. The strong electron transport activity in vegetative cells adjacent to heterocysts appears to promote reducing conditions in the heterocysts. Both, red-formazan formation in the heterocysts and blue-formazan deposition in vegetative cells greatly inhibit nitrogenase activity, and this was adversely affected also by the detachment of heterocysts from vegetative cells. The findings are consistent with the idea that the association of heterocysts with vegetative cells in essential for nitrogen fixation to occur in heterocystous blue-green algae. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Microbiology Springer Journals

Tetrazolium reduction and nitrogenase activity in heterocystous blue-green algae

Fay, Peter; Kulasooriya, S.
Archives of Microbiology , Volume 87 (4) – Dec 1, 1972
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References (27)

Publisher
Springer Journals
Copyright
Copyright © 1972 by Springer-Verlag
Subject
Life Sciences; Biotechnology; Biochemistry, general; Cell Biology; Ecology; Microbial Ecology; Microbiology
ISSN
0302-8933
eISSN
1432-072X
DOI
10.1007/BF00409133
Publisher site
See Article on Publisher Site

Abstract

203 87 87 4 4 Peter Fay S. A. Kulasooriya Department of Botany, Westfield College University of London England Department of Botany University of Ceylon Peradeniya Ceylon Summary Heterocysts reduce triphenyl tetrazolium chloride (TTC) faster than vegetative cells apparently because the absence of the O 2 -evolving photosystem II and the high electron transport activity in these cells. Although the rate of TTC reduction in vegetative cells is increased by the continuous removal of O 2 evolved in photosynthesis, it has not been possible to obtain rates of TTC reduction comparable with those in heterocysts probably because of the continued competition for electrons between TTC and O 2 . The use of nitro-blue tetrazolium chloride (NBT) as a redox indicator has revealed the presence in filaments under aerobic conditions of a gradient of electron transport activity with strongest reducing power in the heterocysts, proheterocysts and vegetative cells next to heterocysts, and with gradually diminishing activity midway between two heterocysts. This pattern is indistinct in filaments grown under micro-aerophilic conditions. The strong electron transport activity in vegetative cells adjacent to heterocysts appears to promote reducing conditions in the heterocysts. Both, red-formazan formation in the heterocysts and blue-formazan deposition in vegetative cells greatly inhibit nitrogenase activity, and this was adversely affected also by the detachment of heterocysts from vegetative cells. The findings are consistent with the idea that the association of heterocysts with vegetative cells in essential for nitrogen fixation to occur in heterocystous blue-green algae.

Journal

Archives of Microbiology – Springer Journals

Published: Dec 1, 1972

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