ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. Of 17 derivatives of 3- and 5-nitropyridine and pyrimidine which inhibited Trichomonas vaginalis in vitro, 7 also inhibited in vivo. The ones with the greatest in vitro activity, and the only ones that were active in vivo, were 5-nitropyridines and pyrimidines with a single substituent at C2. With combinations of compounds, the in vitro inhibitory action was additive. The in vitro inhibitory activity of each was reversed by structurally related compounds, e.g. 2-acetamido-5-nitropyridine. All inhibitors presumably were acting similarly. In later work with 2-amino-5-nitropyrimidine (inhibitor) as model compound, the inhibition represented by extreme prolongation of the generation time was immediately reversible on removal of the inhibitor and without subsequent effect on the lag phase or generation time of the surviving cells even in a population made up of 〉90% non-viable cells.Staining indicated that, after 2-hour growth with inhibitor, mitosis was arrested at prophase. To verify this subjective observation, cells were exposed to both inhibitor and 10−3 M colchicine since after 5-hour growth with colchicine all cells were in “c” (colchicine)-mitosis. If the inhibitor did act at prophase, then cells exposed both to inhibitor and colchicine should proceed only as far as prophase. This proved the case.Since 2-amino-5-nitropyrimidine had the same killing characteristics as 2,4-dinitrophenol (DNP), which blocks mitosis at prophase by inhibiting phosphorylation, the metabolism of resting cells was compared in the presence of 4 × 10−4 M DNP (the concentration 90% growth inhibitory) or 2-amino-5-nitropyrimidine. This concentration of DNP uncoupled phosphorylation since it stimulated the rate of reduction of 2,3,5-triphenyltetrazolium chloride. 2-Amino-5-nitropyrimidine did not change the metabolic rate on simple addition to resting cells. But when cells were grown with at least 40μg/ml for at least 3 hr, endogenous metabolism was inhibited while utilization of malate was stimulated and became linear with time. It was demonstrated that both metabolic disturbances were due to accumulation of diphosphopyridine nucleotide (DPN). Accumulation of DPN was not responsible for prophase blockage. The lesion resulting in prophase blockage remains unknown.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1962.tb02658.x
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