d-Amphetamine was found to induce a pecking response in pigeons. The pecking response induced by d-amphetamine was antagonized by chlorpromazine, haloperidol or bulbocapnine indicating that this pecking response was caused by dopaminergic receptor stimulation. Pretreatment of pigeons with alpha-methyltyrosine (alpha-MT) reduced d-amphetamine-induced pecking, while the combined treatment of pigeons with alpha-MT and L-dihydroxyphenylalanine (L-DOPA, 100 mg/kg) partially restored the pecking response. d-Amphetamine-induced pecking was not reduced by a dopamine-beta-hydroxylase inhibitor, 1-phenyl-3-(2-thiazolyl)-2-thiourea (U-14,624). Alpha-MT reduced brain dopamine but not norepinephrine level, whereas U-14,624 decreased brain norepinephrine but not dopamine. Thus there is a correlation between brain dopamine level and d-amphetamine-induced pecking response. It is concluded that d-amphetamine-induced pecking is mediated indirectly by the release of dopamine.

Animals↗

PubMedDate not supplied

Influence of carbon and nitrogen sources on arginine biosynthesis in Mycobacterium smegmatis ATCC 14468.

Arginine biosynthesis and its regulation by the presence of different carbon and nitrogen sources in the growth medium of Mycobacterium smegmatis was studied. Replacement of glycerol by glucose and fructose increased the activities of acetylglutamate kinase, acetylornithinase and ornithine transcarbamylase and the enzyme activities of the arginine biosynthetic pathway. The presence of succinate, fumarate, pyruvate or acetate in the growth medium (replacement for citrate) also increased these enzyme activities. However, when glutamate or glutamine was used as nitrogen source in place of asparagine, the enzyme activities decreased. The presence of ornithine or arginine in the growth medium repressed these enzyme activities, though the degree of repression was slight. The phenomenon of repression by arginine and ornithine was confirmed by dialysis experiments. Arginine inhibited the ornithine transcarbamylase activity from cells grown with asparagine as nitrogen source, but activated it when the cells were grown with arginine. Thus, in addition to the weak transcriptional control of arginine biosynthetic enzymes, feedback regulation of ornithine transcarbamylase by arginine also regulated arginine biosynthesis in M. smegmatis grown with asparagine as nitrogen source.

Arginine↗

PubMedDate not supplied

Changes in the enzyme activities involved in nitrogen assimilation in Mycobacterium smegmatis under various growth conditions.

Glutamate dehydrogenase (aminating) and glutamine synthetase activities were assayed in Mycobacterium smegmatis following growth on various carbon and nitrogen sources. The activities (expressed as nmoles product formed/min/mg crude extract protein) of these two enzymes were higher in crude extracts from glucose-grown cells than in glycerol- or fructose-grown cells. In the presence of succinate, pyruvate, fumarate or acetate in the growth medium, both these enzyme activities were lower than those in citrate-grown cells. The glutamate dehydrogenase (GDH) activity was the same in asparagine and glutamine-grown cells. Ammonium chloride, alanine or glutamic acid, when used as nitrogen source, resulted in low GDH activity as compared to asparagine-grown cells. Glutamine synthetase activity was considerably lower (2-4 fold) when the cells were grown on alanine, glutamine, glutamic acid or ammonium chloride as the nitrogen source than those in asparagine-grown cells. Glutamate and ammonium chloride, when present in the growth medium, repressed both glutamate dehydrogenase and glutamine synthetase, though the degree of repression was small. The results suggest that only a weak transcriptional control operates for these enzyme activities in M. smegmatis.

Alanine↗

PubMedDate not supplied

[Preservation effects in forensic ABO-determinations using analysis of results as evidence in criminal cases].

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ABO Blood-Group System↗