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PubMed1980

[Simultaneous study of the induction effect of rifampicin and the phenotype for acetylation of isoniazid in 21 patients with tuberculosis undergoing a combination treatment].

Enzyme induction during an antituberculous treatment with Rifampin, Isoniazid and Ethambutol was studied in 21 patients with tuberculosis. Two tests were used: increase in urinary excretion of D-saccharic acid and decrease of the half-life of antipyrineee. Induction is constant with D-saccharic acid. On the other hand there is a significant decrease in the half-life of antipyrin in only 10 patients. There is an increase in the 11 other patients: all of them are slow acetylators for isoniazid. We suggest that INH has an inhibitor effect on the hydroxylation of antipyrin. This study allows us to discuss the interactions of drugs with INH and Rifampin, as well the predominance of rapid acetylators among subjects suffering of isoniazid hepatitis, recently questioned.

Acetylation↗
PubMed2006

[Epilepsy and male sexual dysfunction: etiology, diagnosis and therapy].

While 10% of healthy men had sexual dysfunctions, male epilepsy patients experience sexual problems in 40-70%. The cause of sexual dysfunction in epilepsy is multifactorial, but there are three main factors: the epilepsy itself, antiepileptic treatment and psychiatric/psychic problems. Antiepileptics with hepatic enzyme induction potential (carbamazepine, phenytoin) enhance the metabolism of sexual steroids. Valproic acid as an enzyme inhibitor and drug with high protein binding affinity elevates the free serum levels of androgens. Certain antiepileptic drugs may have negative cognitive side effects, some of them can induce psychiatric disorders. These drugs can facilitate male sexual dysfunctions through these psychic side effects. The metabolic and endocrine alterations caused by carbamazepine may return to normal level after replacement of carbamazepine with oxcarbazepine. After an oxcarbazepine-carbamazepine replacement, carbamazepine-induced impotency can be cured. According some new data lamotrigine can also help in sexual dysfunction. The therapy of sexual dysfunction in epilepsy depends on its cause. In cases of hormonal alterations, the fist step is a change of antiepileptic regimen. Instead of enzyme-inductor antiepileptics and valproate, new antiepileptic drugs should be prescribed. At present, the most investigated antiepileptic drug is the oxcarbazepine with positive effect on antiepileptic-induced male sexual dysfunction, however, lamotrigine seems to be also beneficial. If the hormonal and sexual dysfunctions cannot be eliminated by drug changes, androgenic therapy or bromocriptine may be required. Testosterone may not only be beneficial on sexual functions, but can reduce also the seizure frequency. Independent of etiology, erectile dysfunctions can be successfully treated by sildenafil.

Androgens↗
PubMed1994

Effects of testosterone, hypophysectomy and growth hormone treatment on clofibrate induction of peroxisomal beta-oxidation in female rat liver.

Induction of peroxisomal beta-oxidation by clofibrate under altered hormonal states was investigated in female rat liver. Treatment of rats with clofibric acid (CPIB) caused a significant increase in hepatic peroxisomal beta-oxidation, with female rats being less responsive than males (4.2- vs 12.2-fold increase). However, testosterone treatment following ovariectomy of female rats resulted in an enhanced response to CPIB, giving an induction (11.7-fold) comparable to that seen in male rats. Hypophysectomy of female rats also enhanced the induction (8.2-fold compared with 5.1-fold), suggesting a suppressive effect of a pituitary-dependent factor on CPIB induction of peroxisomal beta-oxidation. Continuous infusion of growth hormone to the hypophysectomized female rats suppressed the enhanced induction nearly to the initial level (6.1-fold). The stimulatory effects of testosterone and hypophysectomy on the enzyme induction were additive. These findings suggest the involvement of growth hormone, as well as male sex hormone, in regulating the responsiveness to CPIB induction of peroxisomal beta-oxidation in rat liver.

Animals↗
PubMed1986

Inducible beta-lactamases are principally responsible for the naturally occurring resistance towards beta-lactam antibiotics in Proteus vulgaris.

The role of inducible chromosomally mediated beta-lactamases was studied in 22 Proteus vulgaris isolates by monitoring enzyme induction in the presence of various inducers such as ampicillin, cefalothin, cefuroxime, cefsulodin, 6-aminopenicillanic acid (6-APS), and imipenem. 20 of the isolates exhibited resistance to ampicillin, cefalothin, and cefuroxime, whereas 2 isolates were susceptible to these compounds. In all resistant isolates marked inoculum effects could be observed. Enzyme production proved to be transient, i.e. maximum of enzyme production was achieved after 2 or 3 h. In both sensitive isolates enzyme production did not exceed 0.021 U beta-lactamase/mg protein of the cell-free supernatant even after induction with 6-APS or imipenem, whereas it ranged from 0.46 to 6.3 U in the resistant ones. Moreover, enzyme induction was found to be concentration-dependent, as revealed by the extensive study of one of the isolates (No. 4917). Three different enzymes could be distinguished by means of isoelectric focusing with isoelectric points at 7.4, 8.8, and approximately 9.5. In the presence of 2.5 mg/l clavulanic acid even strains known to be strong enzyme producers became as susceptible as the sensitive ones: moreover, the inocolum effect was markedly reduced. These findings make it apparent that it is above all the production of inducible enzymes that is responsible for resistance to beta-lactam antibiotics in P. vulgaris.

Anti-Bacterial Agents↗
PubMed1994

Induction of manganese superoxide dismutase by glucocorticoids in glomerular cells.

Our previous in vivo study demonstrated that methylprednisolone (MP) activates glomerular antioxidant enzymes and attenuates glomerular oxidant injuries, including those in experimental nephrosis. The present study investigates the cellular mechanism of the MP-induced activation of antioxidant enzymes and their contribution to the attenuation of cellular oxidant toxicity. When bovine glomerular endothelial cells (GECs) were treated with 10 microM MP, cellular manganese superoxide dismutase (Mn-SOD, 3.95 +/- 0.33 mu/mg protein, M +/- SE) and catalase (1.64 +/- 0.06 k/mg protein) activities were significantly (P < 0.05) elevated above control GECs (2.23 +/- 0.43 mu/mg protein and 1.06 +/- 0.09 k/mg protein, respectively). When GECs pretreated with MP (10 microM 24 hrs) were exposed to xanthine (0.1 mM)+xanthine oxidase (5 mU/ml) for four hours, levels of specific membrane lipid peroxidation products, that is, phosphatidylcholine- and phosphatidylethanolamine-hydroperoxides, remained at levels 10 to 25% of those measured in non-MP-treated (xanthine/xanthine oxidase-exposed) control cells. Moreover, the degree of cell damage following exposure to the superoxide generating system, assessed by 51Cr release, was significantly attenuated in MP-treated cells (approximately 50% of MP-non-treated controls, N = 6). Thus, MP-treated GECs with elevated antioxidant enzyme activities by MP were more resistant to the toxic effect of reactive oxygen metabolites. The mechanism of antioxidant enzyme induction by MP was studied for Mn-SOD. MP was shown to enhance Mn-SOD mRNA in bovine GECs and rat glomerular mesangial cells (GMCs) in dose-dependent manners.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The effects of 1,25-dihydroxyvitamin D3 and dexamethasone on rat osteoblast-like primary cell cultures: receptor occupancy and functional expression patterns for three different bioresponses.

The effects of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] and dexamethasone to regulate collagen and osteocalcin synthesis and induction of 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase) activity were studied in rat osteoblast-like cell primary cultures. In this culture system, the basal levels of collagen and osteocalcin synthesis increased with rising cell density in culture. At maximal doses, both 1,25-(OH)2D3 (8.1 nM) and dexamethasone (130 nM) reduced collagen synthesis to about 50% of the control levels, 1,25-(OH)2D3 affected osteocalcin synthesis in a biphasic manner: stimulatory at low doses, which peaked near 0.33 nM to reach 3- to 5-fold the basal level, followed by a gradual return to the basal level at higher concentrations. Dexamethasone had only a slight stimulatory effect on osteocalcin. 1,25-(OH)2D3 also induced 24-hydroxylase activity in rat osteoblast-like cells, while dexamethasone had no effect on the enzyme. Induction of enzyme activity achieved a 4- to 6-fold rise, but required higher concentrations of 1,25-(OH)2D3 to achieve maximal levels (16 nM). The half-maximal doses (ED50) of 1,25-(OH)2D3 required for each bioresponse were different. The approximate ED50 for the inhibition of collagen synthesis was near the Kin (0.4 nM; apparent dissociation constant of receptor nuclear internalization), while the ED50 for osteocalcin synthesis (0.08 nM) was below the Kin, and the ED50 for 24-hydroxylase induction (20 nM) was greater than the Kin. The ED50 for dexamethasone on collagen synthesis (20 nM) was about 5-fold higher than the Kin (4 nM) of dexamethasone receptor binding. The potencies of various vitamin D3 metabolites in all three functional responses followed their abilities to compete for the 1,25-(OH)2D3 receptor, indicating that these actions were 1,25-(OH)2D3 receptor mediated. In summary, these studies explored bone cell bioresponses to 1,25-(OH)2D3 and dexamethasone and examined the relationship between receptor occupancy and functional expression. Each action exhibited a different dose-response pattern, implying that different levels of control are required for each individual response.

Animals↗
PubMed1992

Studies on the biochemical effects of the aldose reductase inhibitor 2,7-difluorospirofluorene-9,5'-imidazolidine-2',4'-dione (Al 1576, HOE 843). Detection of D-glucaric and D-glucuronic acid excretion by high resolution 1H and 13C NMR spectroscopy.

The effects of two aldose reductase inhibitors on the biochemical composition of rat urine were investigated using high resolution 1H and 13C NMR spectroscopy. We report the elevated excretion of D-glucaric acid (DGA) and D-glucuronic acid (GCA) following treatment with 2,7-difluorospirofluorene-9,5'-imidazolidine-2'4'-dione (Imirestat, IM, Al 1576, HOE 843) at 50 mg/kg/day for 1 month, but not with 3-4-bromo-2-fluorobenzyl-4-oxo-3-phthalazine-1-ylacetic acid (Ponalrestat, Statil), dosed at 50 mg/kg/day for 2 weeks. Sugar aciduria was also detected following treatment with the cytochrome P450 inducer phenobarbitone (PB) at 45 mg/kg/day for 1 month, although the qualitative and quantitative pattern of excretion of sugar acids differed greatly between the IM and PB treatment groups. The levels of GCA excreted are elevated 11-fold by IM treatment from 19.0 to 210.0 mumol/24 hr, but only 2.5-fold by PB, from 9.7 to 23.9 mumol/24 hr. DGA was not detectable in control urine, although levels did increase by 30% during the study from 7.5 to 10.9 mumol/24 hr, between day 8 and day 29, with IM treatment, and by 60% from 1.7 to 4.9 mumol/24 hr following PB administration for the same time period. This predominant elevation of DGA and GCA caused by IM treatment far exceeds previous records. In contrast, PB treatment resulted in an increase in intensity of a number of partially resolved sugar resonances, but at a much lower level than resulted from IM treatment. A raised level of DGA and GCA is usually associated with hepatic P450 induction; however, we report here profound DGA and GCA uria as a result of the inhibition of the aldehyde reductase, hexonate dehydrogenase (EC 1.1.1.19, EC 1.1.1.20). This mechanism is not closely linked to P450 induction, corroborating the current view that elevated excretion of DGA is not a reliable indicator of hepatic enzyme induction. This study further demonstrates the use of high resolution NMR spectroscopy in the detection of a novel biochemical effect which may go unnoticed during routine clinical chemistry tests.

Aldehyde Reductase↗
PubMed1978

Effect of actinomycin D or puromycin on microsomal testosterone hydroxylase activity enhanced by testosterone in female rat liver.

The injection of testosterone propionate for 4 successive days into female rats resulted in an increase of the in vitro conversion of the hydroxylated testosterones from testosterone by the hepatic microsomal fraction, but no change in the content of microsomal cytochrome P-450 occurred. Actinomycin D or puromycin, which was administered for 4 days with injections of testosterone propionate, prevented the enzyme induction.

Animals↗
PubMed1985

Induction of ornithine decarboxylase activity by 1-oleoyl-2-acetyl-glycerol in isolated mouse epidermal cells.

1-Oleoyl-2-acetyl-glycerol induced a rise in ornithine decarboxylase activity in isolated epidermal cells in a concentration-dependent manner. The time course of the induction of ornithine decarboxylase by 1-oleoyl-2-acetyl-glycerol was similar to that by 12-O-tetradecanoylphorbol-13-acetate. A23187 did not enhance the enzyme induction caused by 1-oleoyl-2-acetyl-glycerol. Palmitoyl-DL-carnitine prevented the induction of the enzyme either by 1-oleoyl-2-acetyl-glycerol or 12-O-tetradecanoyl-phorbol-13-acetate. These results suggest that the activation of protein kinase C is an initial and essential event in the process of ornithine decarboxylase induction caused by 12-O-tetradecanoyl-phorbol-13-acetate.

Animals↗
PubMed1976

Effects of prednisolone metasulfabenzoate on the induction of DNase II in comparison to alkaline phosphatase and acid phosphatase activities in cultures of HeLa S3 cells.

Cultures of HeLa S3 cells were treated with prednisolone metasulfobenzoate (Na), a derivative of prednisolone which is readily soluble in water. The steroid induced an increase in DNase II, a lysosomal enzyme which was not used previously in enzyme induction by steroids. Alkaline phosphatase, a known inducible enzyme by other steroids and acid phosphatase, a known uninducible enzyme by other steroids, were included for comparative reasons.

Acid Phosphatase↗
PubMed1998

Induction of hepatic cytochrome P450 2B and P450 3A isozymes in rats by zolazepam, a constituent of Telazol.

Telazol, a 1:1 combination of tiletamine HCl and zolazepam HCl, is an anesthetic and immobilizing agent that is capable of inducing cytochrome P450 (CYP) 2B isozymes in rats. The primary goal of the present study was to determine the constituent of Telazol responsible for the enzyme induction. A secondary goal was to compare the effects produced by Telazol and its constituents with those elicited by sodium phenobarbital (PB) using the same dosing regimen. Adult male Long Evans rats were given a single i.p. injection of tiletamine or zolazepam at a dose of 60 mg/kg, Telazol at a dose of 120 mg/kg, PB at a dose of 60 and 120 mg/kg, or vehicle at a dose of 1 mL/kg. Animals were killed 24 hr later, and hepatic microsomes were prepared. Treatment with zolazepam and Telazol increased microsomal benzyloxyresorufin O-dealkylase (BROD) activity by approximately 9- and 15-fold, respectively, and increased microsomal testosterone 16 beta-hydroxylase activity by 5- and 8-fold, respectively. Treatment with tiletamine had a slight, but insignificant, effect on CYP-mediated enzyme activities. In comparison, BROD and testosterone 16 beta-hydroxylase activities were increased by 22- and 13-fold, respectively, after treatment with PB at a dose of 60 mg/kg. Densitometric quantitation of immunoblots revealed that the hepatic CYP2B content was elevated by approximately 15-, 22-, and 25-fold, and the hepatic CYP3A content was increased by 2-, 2-, and 8-fold after treatment with zolazepam, Telazol, and PB, respectively. In contrast, levels of CYP1A1 and CYP2E1 were unaltered after treatment. In summary, the results indicate that zolazepam was the constituent primarily responsible for the inductive effect of Telazol, and the pattern of enzyme induction produced by zolazepam and Telazol was similar to, but weaker than that elicited by PB at a similar dosing regimen.

Animals↗
PubMed1998

Evaluation of octamethylcyclotetrasiloxane (D4) as an inducer of rat hepatic microsomal cytochrome P450, UDP-glucuronosyltransferase, and epoxide hydrolase: a 28-day inhalation study.

Repeated inhalation exposure to octamethylcyclotetrasiloxane (D4) produces a reversible and dose-related hepatomegaly and proliferation of hepatic endoplasmic reticulum in rats. However, the effects of D4 on the expression of cytochrome P450 enzymes have not been evaluated. In the present study, the time course for changes in hepatic microsomal cytochrome P450 enzyme expression following repeated inhalation exposure to D4 vapors was determined in male and female Fischer 344 rats. Animals were exposed to D4 vapor at concentrations of 70 and 700 ppm, via whole body inhalation for 6 h/day, 5 days/week for 4 weeks. Specified animals were euthanized on exposure days 3, 7, 14, 21, and 28. Microsomal fractions were prepared from fresh liver by differential centrifugation. Enzyme activity as well as immunoreactive protein levels of several cytochrome P450 enzymes (CYP), epoxide hydrolase, and UDP-glucuronosyltransferase (UDPGT) were evaluated. The time course for enzyme induction was monitored by measuring 7-ethoxyresorufin O-deethylase (EROD) and 7-pentoxyresorufin O-depentylase (PROD) activities on days 3, 7, 14, 21, and 28. CYP1A1/2 activity, as determined by EROD activity, was increased approximately 2- to 3-fold over the exposure period. However, an examination of immunoreactive protein revealed no induction of CYP1A1 and a suppression of CYP1A2 in the 700 ppm D4 group. In comparison, CYP2B1/2 enzyme activity, as determined by PROD, was significantly increased as early as day 3 in both the 70 and 700 ppm D4 groups of male and female rats. Overall, PROD activity on day 28 was induced more than 10-fold in the 70 ppm D4 groups and more than 20-fold in the 700 ppm D4 groups. The increase in PROD activity was paralleled by a comparable increase in CYP2B1/2 immunoreactive protein. There was a modest (2- to 3-fold) increase in CYP3A1/2 activity and immunoreactive protein, as determined by 6 beta-hydroxylation of testosterone and Western blot analysis. Expression of CYP enzymes was at or near maximum by day 14 and remained relatively constant throughout the exposure period. On day 28, epoxide hydrolase activity and immunoreactive protein were induced (2- to 3-fold) in a dose-dependent manner. Only slight changes in the expression and activity of UDPGT were detected, and these did not appear to be dose related. Thus, repeated inhalation exposure to D4 induces CYP enzymes and epoxide hydrolase in a manner similar to that observed for phenobarbital (PB). Therefore, D4 can be described as a "PB-like" inducer of hepatic microsomal enzymes in the Fischer 344 rat.

Adjuvants, Immunologic↗
PubMed2005

Betalains, phase II enzyme-inducing components from red beetroot (Beta vulgaris L.) extracts.

Crude aqueous and ethanolic extracts of root tissue of red (Rd) and high-pigment (HP) beet (Beta vulgaris L.) strains exhibited antioxidant and phase II enzyme-inducing activities, and these extracts were fractionated using Sephadex LH-20 chromatography. These bioactivities tended to become co-enriched in early and late eluting fractions, comprising 5-25% of the material recovered from the column. Liquid chromatography-mass spectrometry (MS) was used to resolve and identify multiple betalain components in the most potent quinone reductase (QR)-inducing fractions. Active fractions were found to contain vulgaxanthins I and II, and (iso)betanin, but other components remained unidentified. Two of the isolated active fractions were incorporated into rodent diets at 10-150 ppm over a 2-mo period to assess bioavailability and in vivo efficacy for phase II enzyme induction in various organs. No statistically significant effect of diet was obtained, and wide ranges of tissue enzyme levels among individual animals were observed. This lack of effect and diversity in response to diet may be related to the wide range in absorptive capacity of and/or insufficient level or enrichment of the active agents or to difficulties in assessing such activity in vivo. Subsequent to the animal studies, betanin was isolated in pure form, identified by MS analysis, and confirmed to be QR inducers in the bioassay.

Animals↗
PubMed1992

Serotonin N-acetyltransferase (NAT) induction in mammalian retina: role of cyclic AMP and calcium ions.

In retinas and pineal glands of rat, rabbit and hen, activities of the penultimate (and key regulatory) enzyme in melatonin biosynthesis, serotonin N-acetyltransferase (NAT), display distinct diurnal variations, with high and low values during dark and light phase of a 12-h dark: 12-h light illumination cycle. Two-hour incubation (during daytime hours in light) of isolated pineal glands of the studied vertebrates, or the retinas, with 50 microM forskolin (plus 100 microM 3-isobutyl-1-methylxanthine, IBMX-a phosphodiesterase inhibitor), and 1 mM dibutyryl-cAMP, markedly increased the tissue NAT activity. The same procedures significantly enhanced the enzyme activity of rat retina in light, however, only during nighttime hours. The forskolin (+ IBMX)-induced increase of NAT activity in rat retina was significantly lower in a calcium-free medium, and substantially enhanced when calcium concentration was raised from 1.3 mM to 3.9 mM. Treatment of rats with IBMX or aminophylline, and rabbits with aminophylline, increased NAT activity in their pineal glands irrespective of the time of the day, whereas both phosphodiesterase inhibitors significantly increased the enzyme activity of rat retina only when injected during the subjective dark hours. It is concluded that, by analogy to vertebrate pineal gland, in vertebrate retina an increase of NAT activity (and consequently melatonin formation), stimulated both physiologically (i. e. at night), or pharmacologically, involves a cAMP- and calcium dependent process of the enzyme induction.

1-Methyl-3-isobutylxanthine↗
PubMed1975

Exposure to an environment containing the aromatic red cedar, Juniperus virginiana: procarcinogenic, enzyme-inducing and insecticidal effects.

(1) Shavings from the Eastern Red Cedar (Juniperus virginiana) were examined for three diverse biological properties, i.e. enzyme induction, procarcinogenicity and insecticidal activity. (2) The ability of a cedar environment to stimulate liver drug-metabolizing enzymes in mice was confirmed by lowered values for barbiturate sleeping time. (3) In susceptible strains of mice (C3H-Avy, C3H-AvyfB and CBA/J) the use of cedar shavings as bedding increased significantly the incidence of spontaneous tumors of the liver and mammary gland, and also reduced the average time at which tumors appeared. (4) Cedar and some of its derivatives (Oil of Cedarwood, cedrene, cedrol) disrupted the reproductive and developmental cycle of a number of insects, including the Peanut Trash Bug (Elasmolomus sordidus), the Indian Meal Moth (Plodia interpunctella) and the Forage Mite (Tyrophagus putrescentiae).

Animals↗
PubMed1999

Relation of structure of curcumin analogs to their potencies as inducers of Phase 2 detoxification enzymes.

A series of naturally occurring as well as synthetic structural analogs of the dietary constituent curcumin were examined in order to elucidate which portions of the molecule are critical for the ability to induce Phase 2 detoxification enzymes in murine hepatoma cells, and hence to assess the chemoprotective potential of these compounds. Two groups of compounds were studied: classical Michael reaction acceptors such as curcumin and related beta-diketones such as dibenzoylmethane which lack direct Michael reactivity. The presence of two structural elements was found to be required for high inducer potency: (i) hydroxyl groups at ortho-position on the aromatic rings and (ii) the beta-diketone functionality. All curcuminoids elevate the specific activity of quinone reductase in both wild type and mutant cells defective in either the aryl hydrocarbon (Ah) receptor or cytochrome P4501A1 activity. This indicates that neither binding to this receptor, nor metabolic activation by P4501A1 are required for the signaling process originating from this family of electrophiles and ultimately resulting in Phase 2 enzyme induction.

Animals↗
PubMed1981

Induction of plasminogen activator by UV light in normal and xeroderma pigmentosum fibroblasts.

Normal and DNA repair-deficient human fibroblasts have been used to study induction of plasminogen activator (PA) by DNA damage. UV light induced the synthesis of PA in skin fibroblasts of all types of xeroderma pigmentosum (XP) in XP heterozygotes and in human amniotic cells. Enzyme induction was, however, not observed in fibroblasts of normal adults. In classical XP, which are deficient in excision repair, PA synthesis occurred in a narrow range of low-UV fluences. In such strains, the level of enzyme produced was correlated with the extent of repair deficiency. UV fluences required for PA induction in XP variants and XP heterozygotes were at least 10 times those inducing enzyme synthesis in excision-deficient XP. Maximum enzyme induction occurred 48 hr after irradiation, and the highest levels of enzyme produced were 15-20 times those of PA baseline levels. Electrophoretic analysis showed that UV irradiation enhances the synthesis of the Mr 60,000 human urokinase-type PA, which is present in low amounts in untreated cells. Our results suggest that PA induction in human cells is caused by unrepaired DNA damage and represents a eukaryotic SOS-like function. In addition, PA induction may provide a sensitive assay for detection of cellular DNA repair deficiencies and identification of XP heterozygotes.

Amniotic Fluid↗
PubMed2005

Maltose adaptive mutant of heterotrophic marine bacterium, Alteromonas espejiana Bal-31: changes in the growth and the induction of extracellular alpha-amylase.

Growth of the heterotrophic marine bacterium, Alteromonas espejiana Bal-31 was inhibited in the presence of sucrose, maltose and even glucose, but not with starch. Extracellular alpha-amylase was induced with a lag phase of 2 h in the presence of starch. In contrast, cell growth of the S2a mutant was not affected by the addition of maltose, and starch was ineffective in the induction of extracellular alpha-amylase in this mutant. Activity of extracellular alpha-amylase was induced from the S2a mutant with a 4-h lag phase in the presence of maltose, and the high level of enzyme activity was maintained for at least 24 h. Activity of alpha-amylase induced by both wild type starch and S2a mutant maltose cultures were mainly observed in extracellular locations. This activity could be stopped by tetracycline treatment, indicating that enzyme induction was dependant on gene expression and not on enzyme protein secretory mechanisms. Our results showed that the mutation in S2a changed the growth and the modulation of the specific alpha-amylase in response to carbon nutrients.

Adaptation, Physiological↗