Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five-or six-day old seedlings of corn (Zea mays L.) were exposed to 0.25 mm Ca(NO(3))(2), 1.0 mm sodium 2-[N-morpholino]-ethanesulfonate, 5 mug Mo per liter and 50 mug of chloramphenicol per ml at pH 6. Nitrate uptake was determined from depletion of the ambient solution. The pattern of nitrate uptake was characterized, after the first 20 minutes, by a low rate which increased steadily to a maximal rate by 3 to 4 hours. Transfer of nitrate to the xylem did not totally account for the increase. Development of the maximal accelerated rate did not occur at 3 C with excised roots nor with seedlings whose endosperm had been removed. Use of CaCl(2) rather than Ca(NO(3))(2) resulted in a linear rate of chloride uptake during the first 4 hours, and chloride uptake was not as restricted by endosperm removal as was nitrate uptake.Nitrite pretreatments or the addition of cycloheximide (2 mug ml(-1)), puromycin (400 mug ml(-1)) and 6-methylpurine (0.5 mm) restricted maximal development of the accelerated nitrate uptake rate. Actinomycin D (20 mug ml(-1)) inhibited the rate only after about three hours exposure. The RNA and protein synthesis inhibitors also restricted nitrate reductase induction in the apical segments of the root tissue. The data suggest that development of the maximal accelerated rate of nitrate uptake depended upon continuous protein synthesis, and the hypothesis that synthesis of a specific nitrate transport protein must occur is advanced. But the alternative hypothesis, i.e., that induction of nitrate reductase (and/or a consequence of the act of nitrate reduction) provided the required stimulus, remains tenable.
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PMID:Nitrate Uptake by Dark-grown Corn Seedlings: Some Characteristics of Apparent Induction. 1665 72

Actinomycin D at 10 mug/ml strongly inhibited the increase in isocitrate lyase activity during germination of seeds and 40-day-old embryos of cotton (Gossypium hirsutum L.) when the germination period was preceded by 3 hours of soaking in the inhibitor solution. No inhibition was observed without the presoaking. Induction of nitrate reductase activity by nitrate was never inhibited by actinomycin D under the same conditions, and was frequently stimulated about 50%. Thus, the method of applying actinomycin D to the seeds and ovules could affect interpretation of its action. Abscisic acid at 5 mug/ml blocked production of isocitrate lyase activity in both pregermination treatments, but did not inhibit induction of nitrate reductase activity. Induction of nitrate reductase activity became insensitive to the two inhibitors during ovule maturation, at about 32 days after anthesis. The results indicate that isocitrate lyase, a germination enzyme, is not synthesized on performed mRNA. In this respect, the appearance of activity in cotton resembles that in other species of fatty seeds. In contrast, induction of nitrate reductase activity, which is unnecessary for germination, apparently is not regulated at the level of transcription except in young ovules.
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PMID:Control of Enzyme Activities in Cotton Cotyledons during Maturation and Germination: I. Nitrate Reductase and Isocitrate Lyase. 1665 95

Induction of nitrate reductase (EC 1.6.6.1) activity was measured in Paul's Scarlet rose cell suspensions cultured in media containing nitrate (NO 3 (-) ) or urea (U) as nitrogen source, and with (+Mo) or without molybdenum (-Mo). There was a lag of 30 min during induction by NO 3 (-) in +Mo cultures but no lag occurred during induction after adding Mo to NO 3 (-) -Mo or to U-Mo cultures preincubated with NO 3 (-) . Actinomycin D, cycloheximide, and puromycin completely blocked induction by NO 3 (-) , but had no effect on the initial rate of induction by Mo. Cycloheximide and puromycin blocked induction by NO 3 (-) more quickly than actinomycin D. Induction by NO 3 (-) appeared to involve mRNA-dependent synthesis of apoprotein followed by rapid activation with molybdenum in intact cells independently of protein synthesis. Nitrate-induced apoprotein appeared less stable than the holoenzyme. When induced by NO 3 (-) in the absence of Mo, apoprotein concentration was about half the amount of maximally induced nitrate reductase. Cycloheximide stabilised preformed nitrate reductase which disappeared steadily in the presence of puromycin. Apoprotein was not stabilised by either antimetabolite.
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PMID:Nitrate reductase activity in Paul's scarlet rose suspension cultures and the differential role of nitrate and molybdenum in induction. 2441 75