The addition of antimycin A during the logarithmic phase of growth of heterotrophic Euglena gracilis cultures (in lactate or glucose medium) was immediately followed by decreased respiration and a cessation of grwoth. Induced cyanideresistent respiration appeared 5 h after the addition of the inhibitor then the cells started to grow again and could be cultured in the presence of antimycin A. Thus the cells exhibited a cyanide-and antimycin-resistant respiration which was, in addition, sensitive to salicylhydroxamic acid and propylgallate. Antimycin-adapted Euglena and control cells were compared for their biomass production and protein synthesis. The difference in growth yield between control and antimycin-adapted cells was not as high as would be expected if only the first phosphorylation site of the normal respiratory chain was active in the presence of antimycin A. Furthermore, the ability to incorporate labelled valine into proteins, under resting-cell conditions, was not changed. Strong correlations were established between the effects of respiratory effectors on O2 consumption and valine incorporation. These results suggest that sufficient energy for protein synthesis and growth is provided by the operation of the cyanide-resistant respiratory pathway in antimycin-adapted Euglena.
Markush Darc expresses the genericity which is present in patent chemical structures by the use of generic groups as well as infinite and closed set superatoms. New tools are offered to the user for performing more efficient searches: superatom translation attributes and variable positions of attachment may now be input in the structure query. Operation of these new functionalities is described within screen searchBit Screen and FRELs screenand the exact atom-by-atom match. The contribution of superatoms to the Bit Screen content, the reduction of FRELs subgraph, and the effects of superatom translation on the backtracking mechanism of atom-by-atom search are discussed. Associated optimizations of the whole system were necessary to earn maximal efficiency from these strategic changes in the software.
Etiolated Euglena gracilis Pringsheim, strain Z, were cultured in a lactate medium either in the presence of 2 μM antimycin A for cells adapted to this inhibitor, or in the absence of antimycin A for controls. The adenylates (ATP, ADP and AMP) and the energy charge (EC) were followed during the growth of both types of cells. The effects of KCN, salicylhydroxamic acid (SHAM) and rotenone on the respiration and the adenylate pool, were investigated during the exponental and stationary phases. EC values of controls and antimycin‐adapted cells were not significantly different during culture. In the logarithmic phase, EC of controls was unaffected by 3 mM SHAM, an inhibitor of the alternative pathway, but markedly decreased by 0.3 mM KCN, which inhibits the cytochrome pathway. In contrast, in antimycin‐adapted Euglena, in which the cytochrome pathway was blocked, ATP content and EC were markedly lowered in the presence of SHAM but slightly increased by 0.3 mM KCN. The combination of the preceeding treatments, as well as 15 mM KCN alone, were deleterious for both types of cells, in the logarithmic and the late stationary phases. The data indicate that the energy level in Euglena was dependent on the alternative pathway when the cytochrome pathway was blocked. Such dependence could be explained by the engagement of the first rotenone‐sensitive site of phosphorylation. Indeed, 50 μM rotenone caused a similar relative decrease of oxygen consumption and ATP content in controls and in antimycin‐adapted Euglena. In the absence of cytochrome respiration, the alternative pathway allowed electrons to flow through this first segment of the respiratory chain, and ATP production by the first site of phosphorylation.
Influence of the alternative respiratory pathway on the adenylate pools in heterotrophic Euglena gracilis. -Physioi. Plant. 79:, 303-310.Etiolated Euglena gracilis Pringsheim, strain Z, were cultured in a lactate medium either in the presence of 2 [iM antimycin A for cells adapted to this inhibitor, or in the absence of antimycin A for controls. The adenylates (ATP, ADP and AMP) and the energy charge (EC) were followed during the growth of both types of cells. The effects of KCN, sahcylhydroxamic acid (SHAM) and rotenone on the respiration and the adenylate pool, were investigated during the exponental and stationary phases. EC values of controls and antimycin-adapted cells were not significantly different during culture. In the logarithmic phase, EC of controls was unaffected by 3 mM SHAM, an inhibitor of the alternative pathway, but markedly decreased by 0.3 mM KCN, which inhibits the cytochrome pathway. In contrast, in antimycin-adapted Euglena, in which the cytochrome pathway was blocked, ATP content and EC were markedly lowered in the presence of SHAM but slightly increased by 0.3 mJM KCN. The combination of the preceeding treatments, as well as 15 mM KCN alone, were deleterious for both types of cells, in the logarithmic and the late stationary phases. The data indicate that the energy level in Euglena was dependent on the alternative pathway when the cytochrome pathway was blocked. Sach dependence could be explained by the engagement of the first rotenone-sensitive site of phosphorylation. Indeed, 50 \>.M rotenone caused a similar relative decrease of oxygen consumption and ATP content in controls and in antimycin-adapted Euglena. In the absence of cytochrome respiration, the alternative pathway allowed electrons to flow through this first segment of the respiratory chain, and ATP production by the first site of phosphorylation.
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