Proliferating bloodstream-form Trypanosoma brucei use a negligible part of consumed glucose for anabolic processes
2012
Haanstra, Jurgen R. | van Tuijl, Arjen | Dam, Jan van | van Winden, Wouter | Tielens, Aloysius G.M. | van Hellemond, Jaap J. | Bakker, Barbara M.
Our quantitative knowledge of carbon fluxes in the long slender bloodstream form (BSF) Trypanosoma brucei is mainly based on non-proliferating parasites, isolated from laboratory animals and kept in buffers. In this paper we present a carbon balance for exponentially growing bloodstream form trypanosomes. The cells grew with a doubling time of 5.3h, contained 46μmol of carbon (10⁸ cells)⁻¹ and had a glucose consumption flux of 160nmolmin⁻¹ (10⁸ cells)⁻¹. The molar ratio of pyruvate excreted versus glucose consumed was 2.1. Furthermore, analysis of the ¹³C label distribution in pyruvate in ¹³C-glucose incubations of exponentially growing trypanosomes showed that glucose was the sole substrate for pyruvate production. We conclude that the glucose metabolised in glycolysis was hardly, if at all, used for biosynthetic processes. Carbon flux through glycolysis in exponentially growing trypanosomes was 10 times higher than the incorporation of carbon into biomass. This biosynthetic carbon is derived from other precursors present in the nutrient rich growth medium. Furthermore, we found that the glycolytic flux was unaltered when the culture went into stationary phase, suggesting that most of the ATP produced in glycolysis is used for processes other than growth.
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