Effect of age on ease of B-cell tolerance induction

It was shown in intact mice, and in lethally irradiated, thymectomized recipients of peripheral B cells from donors of various ages, that the ease of B-cell tolerance induction with the dinitrophenyl derivative of the copolymer of d-glutamic acid and d-lysine decreases with age. That is, the B-cell population of 6- to 7-month-old BALB/c mice is more resistant to tolerance induction than is the B-cell population of $\text{1}\text{1}\text{2}$- to 2-month-old mice and the B-cell population of 10- to 11-month-old mice is highly resistant to tolerance induction. This age-related resistance of the peripheral B-cell population to tolerance induction might, at least in part, account for the increased incidence of autoantibodies in aged animals. However, the increased resistance to tolerance induction appears to occur at an earlier age than the increased incidence of autoantibodies. This suggests that changes in ease of tolerance induction may not be the sole factor responsible for the increase in autoantibodies in aged animals. Evidence is also presented for an age-related decrease in the function of the B-cell population with respect to the response to a T-dependent antigen.     

The interaction of auxin and cytokinin in the induction of phenylalanine ammonia-lyase in suspension cultures of Phaseolus vulgaris

The dependence of phenylalanine ammonialyase (PAL) induction in bean suspension cultures on the concentration of naphthylacetic acid (NAA) and kinetin has been investigated and the timing of the effect of each hormone has been determined. NAA was required at an optimal concentration of 1 mg l^-1 2 days prior to the increase in PAL activity. Kinetin caused a prapid stimulation of the rate of PAL induction and the total amount of PAL induced in a concentration range of 0.1–0.5 mg l^-1 when it was supplied to the cells immediately prior to the expected rise in PAL activity. The inhibitory effect of 2 mg l^-1 NAA on PAL induction was overcome by an increased concentration of kinetin.Abbreviations NAA naphthylacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3yl acetic acid - PAL phenylalanine ammonia-lyase (EC 4.3.1.5.)     

Effect of Carbachol and 56 mM-Potassium Chloride on the Cyclic AMP-Mediated Induction of Tyrosine Hydroxylase in Neuroblastoma Cells in Culture

Abstract: Tyrosine hydroxylase (TH) activity is increased two- to threefold in neuroblastoma cell line NBP² maintained in culture for 48 h in the presence of either the inhibitor of cyclic AMP-phosphodiesterase (PDE), 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (RO 20- 1724), or the activator of adenylate cyclase, prostaglandin E₁ (PGE₁). Cyclic AMP levels are elevated 70–80% and 30–40% throughout the 48-h treatment with RO 20-1724 and PGE₁, respectively. Carbachol does not affect either basal TH activity or cyclic AMP levels in the cells. However, the cholinergic agonist delays the induction of TH elicited by either RO 20-1724 or PGE₁. This delay is prevented by atropine. The elevation in cyclic AMP levels elicited by either RO 20-1724 or PGE₁ is blocked for 1 h or 15 min. respectively, after treatment with carbachol. Cyclic AMP levels then begin to rise until they reach those levels observed in the presence of RO 20-1724 or PGE₁ alone by 12 h or 1 h of treatment, respectively. Time course studies demonstrate that this transient inhibition of the elevation of cyclic AMP is associated with a 48-h delay in the induction of TH elicited by either RO 20-1724 or PGE₁. In contrast, the induction elicited by 8-bromo cyclic AMP is unaffected by carbachol. A depolarizing concentration (56 mM) of KCl produces a 24-h delay in the induction of TH elicited by RO 20-1724, without affecting the concomitant elevation of cyclic AMP produced by the PDE inhibitor. Furthermore, 56 mM-KCl inhibits the induction of TH elicited by 8-bromo cyclic AMP. It thus appears that carbachol delays the induction of TH by transiently inhibiting the elevation of cyclic AMP, whereas potassium depolarization delays the induction of TH by inhibiting a process with a site of action that is distal to the elevation of cyclic AMP.     

马兜铃不含腋芽茎段不定芽的诱导

为建立马兜铃(Aristolochia debilis Sieb.et Zucc)不含腋芽茎段的不定芽诱导体系,采用正交设计方法研究植物生长调节剂、预培养方式和AgNO3对不定芽诱导的影响。结果表明:植物生长调节物质对不定芽诱导的影响以TDZ6-BAIAA,其中TDZ的影响极显著(P0.01),6-BA的影响显著(P0.05)。不定芽诱导的最适培养基为MS+0.5 mg L–1 TDZ+0.1 mg L–1IAA+0.5 mg L–1 6-BA+2 mg L–1 AgNO3+3%蔗糖+0.6%琼脂(pH 5.8);预培养方式为在MS+0.1 mg L–1 2,4-D+3%蔗糖+0.6%琼脂培养基上暗培养2 d。马兜铃不含腋芽茎段的不定芽诱导率最高可达37.5%。     

The interaction of respiration and photosynthesis in induction of nitrate reductase activity

The respiration and photosynthesis requirement for induction and maintenance of nitrate reductase activity was determined on leaves of Hordeum vulgare L. In this induction, glucose substituted for light in both dark-grown and carbohydrate-depleted green leaves. Oxygen appeared to be required for induction in all cases studied. In light and under N₂, 3-(3,4-dichlorophenyl)-1,1-dimethylurea completely inhibited induction, presumably by inhibiting the production of O₂, Hence, under N₂ the leaves appeared to utilize both the O₂ produced by photosynthesis and the CO₂ produced by respiration. CO₂ fixation can then produce both photosynthate to drive the induction and terminal electron acceptors to allow photosynthetic electron flow. This possibility was further suggested by the observation that CO₂ was an absolute requirement for induction in carbohydrate-depleted barley leaves. Results obtained with respiratory inhibitors also indicated that respiration drove the induction of nitrate reductase.     

离体培养黄瓜子叶诱导雌花的研究

采用添加Spd和IAA的MS培养基培养离体黄瓜子叶,研究了Spd和IAA对雌花诱导的协同作用,及昼夜温差、培养基中N素和pH值对雌花诱导的影响。结果表明,分别添加Spd、IAA时的雌花诱导率和单株雌花数偏低或为0,12 mg·L^-1 Spd与0.01mg·L^-1 IAA 配合时的诱导效果明显高于单独处理的,而对照组未见雌花,说明Spd和IAA对雌花诱导的协同作用显著。在0、2、6、10℃昼夜温差,60、70、80、90 mmol·L^-1的N素含量和pH 5.4、5.8、6.2、6.6的培养条件下,70 mmol·L^-1 N、6℃温差和pH 6.2时的雌花诱导效果较好,表明适当提高昼夜温差、培养基中N素和pH值有利于黄瓜子叶的雌花诱导。     

Induction of pumpkin glutathione S-transferases by different stresses and its possible mechanisms

Induction of pumpkin (Cucurbita maxima Duch.) glutathione S-transferases (GSTs) by different stresses and endogenous trans-2-hexenal content were determined in search of a common signal for GST induction. All of the stresses showed significant induction, As₂O₃ causing the highest induction followed by trans-2-hexenal. The trans-2-hexenal content was highest in trans-2-hexenal-treated seedlings and next-highest in methyl jasmonate-treated seedlings, whereas high temperature- and As₂O₃-treated seedlings had trans-2-hexenal contents lower than that of control seedlings. Induction of GST, lipoxygenase (LOX) and hydroperoxide lyase (HPL) was compared, since trans-2-hexenal and methyl jasmonate are the products of the LOX pathway. All four stresses showed weak LOX induction, high temperature causing the highest induction. However, only methyl jasmonate caused weak HPL induction. Both antioxidants or oxidants induced GST to different degrees. Glutathione contents of reduced glutathione (GSH) or oxidized glutathione (GSSG)-treated seedlings were significantly higher than the content of control seedlings, whereas those treated with other antioxidants or oxidants had contents similar to or less than control seedlings. The GSH:GSSG ratio was lowest in GSSG-treated seedlings and next-lowest in GSH-treated seedlings. The results of this study suggest that pumpkin GSTs are not induced through a common signalling pathway and that redox perturbation plays a role in pumpkin GST induction.     

碳氮源对花榈木胚性愈伤组织诱导、发育及有机物积累的影响

为探讨花榈木体胚发生过程中不同碳氮源处理对胚性愈伤组织诱导、发育和有机物积累的影响,并筛选出有利于花榈木体胚发生的碳氮源,优化体胚发生体系,该研究以成熟胚为外植体,通过单因素试验分析3种碳源、4种蔗糖浓度和6种氮源处理下胚性愈伤组织诱导、发育和有机物积累的差异。结果表明：(1)蔗糖中胚性愈伤组织诱导率显著高于葡萄糖和麦芽糖,但其体胚诱导率、体胚分化率、胚性愈伤组织可溶性糖、淀粉和可溶性蛋白含量差异不显著。(2)随着蔗糖浓度的升高,胚性愈伤组织、体细胞胚(体胚)诱导率、体胚分化率、胚性愈伤组织重量和可溶性蛋白含量呈先升高后降低的趋势,均以添加30 g·L^-1蔗糖最高,而胚性愈伤组织可溶性糖和淀粉含量呈增加的趋势。(3)在6种氮源处理中,胚性愈伤组织诱导率以添加500 mg·L^-1谷氨酰胺的处理最高,体胚诱导率则以添加谷氨酰胺和水解酪蛋白的处理较高,但不同氮源处理间体胚分化率无差异;添加有机氮源的处理其胚性愈伤组织可溶性蛋白含量显著高于无氮源处理。总之,不同的碳氮源通过影响花榈木胚性愈伤组织的诱导、发育和有机物的积累,从而影响其体胚诱导率,但对体...     

速生湿地松良种胚性愈伤组织诱导与增殖

为使速生湿地松良种快速大规模繁殖,对其胚性愈伤组织进行诱导和增殖优化研究.该文以1代湿地松种子园中10个速生湿地松优良无性系(基因型)的未成熟合子胚为外植体,系统研究基因型、合子胚发育阶段、基本培养基、植物生长调节剂种类和浓度等不同因子对胚性愈伤组织诱导效率的影响,探讨胚性愈伤组织的增殖条件.结果表明:基因型、合子胚发...     

Induction of anaesthesia with sevoflurane and isoflurane in the rabbit

The effects of induction of anaesthesia with sevoflurane and isoflurane were studied in rabbits. All rabbits had periods of apnoea (ranging from 30-180 s) during induction which resulted in moderate hypercapnia and acidosis. Arterial pCO2 rose from 4.1 +/- 0.3 kPa to a peak of 7.6 +/- 0.4 kPa (mean +/- SD) (both agents). All animals showed a significant reduction in heart rate (P < 0.05). Heart rate (HR) fell from 226 +/- 33 to a minimum during induction of 57 +/- 32 (sevoflurane) and 199 +/- 41 to 45 +/- 11 (isoflurane). Most animals struggled violently during induction. Use of sevoflurane did not prevent the breath-holding response seen during induction of anaesthesia with other volatile anaesthetics in this species, and the severe apnoea which occurs may represent a significant hazard. The behaviour of the animals indicated that both sevoflurane and isoflurane are aversive, suggesting that this technique should be avoided whenever possible.     

The reversal of experimental porphyria and the prevention of induction of hepatic mixed-function oxidase by acetate

The administration of acetate or sulfanilamide depressed the porphyric response of rats to 3,5-dicarbethoxy-1,4-dihydrocollidine. The induction of δ-aminolevulinate synthetase (EC 2.3.1.37) in porphyric rats was decreased by acetate administration and δ-aminolevulinate synthetase activity in hepatic homogenates was inhibited by acetate. Succinate reversed the inhibition by acetate in vitro. Since an alteration of heme biosynthesis by acetate was observed, the effect of acetate on the induction of hepatic microsomal cytochrome P-450 and microsomal mixed-function oxidase by phenobarbital was examined. Acetate prevented the induction of hepatic mixed-function oxidase and cytochrome P-450 by phenobarbital. Unlike the action of other inhibitors of hepatic heme biosynthesis, acetate also prevented the induction by phenobarbital of NADPH-cytochrome c reductase (EC 1.6.99.3). These findings suggest that acetate may be inhibiting heme biosynthesis by effects on δ-aminolevulinate synthetase, the rate-limiting step in heme biosynthesis, by alteration of the induction of this enzyme and by a direct effect on the enzymic reaction itself. It is suggested that acetate may be involved in the glucose effect related to the inhibition of the induction of δ-aminolevulinate synthetase.     

Comparison of the Ames assay and the induction of sister chromatid exchanges: Results with ten pharmaceuticals and five selected agents

Seven antischistosomal drugs, two antimalarial drugs, and one antiamoebic drug were tested in all five Ames strains for induction of mutation, as well as for induction of cytotoxicity, inhibition of cellular progression, and the induction of sister chromatid exchanges in two cultured mammalian cell lines. We found that two agents shown to be negative in the Ames test were positive for sister chromatid exchange induction. Based on qualitative and quantitative evaluation, we find that all but three of the pharmaceuticals should be considered to be potential human carcinogens.Abbreviations AA 2-aminoanthracene - 9AACC 9-aminoacridine - AM amoscanate - BrdUU bromodeoxyuridine - CA chloroquine diphosphate - CHO Chinese hamster ovary - CQ chloroquine - DAPI 46-diamidino-2-phenylindole - DHY dehydroemetine - DMSO dimethyl sulfoxide - EB ethidium bromide - FCS fetal calf serum - FN 4-fluoro-3-nitrophenyl azide - HY hycanthone - ICP inhibiting cell progression - LU lucanthone - MEM minimal essential medium - 2NF 2-nitrofurantoin - 4NPD 4-nitro-O-phenylenediamine - NZ niridazole - OL oltipraz - OX oxaminiquine - PBS phosphate buffered saline - PQ primaquine - PZ praziquantel - SA sodium azide - SCE sister chromatid exchange     

Identification of an immediate-early salicylic acid-inducible tobacco gene and characterization of induction by other compounds

Tobacco genes that are induced in response to salicylic acid (SA) treatment with immediate-early kinetics were identified by differential mRNA display. Detailed analysis of IS10a, one cDNA clone identified by this method, revealed induction within 30 min of treatment, with a peak of expression at 3 h, that decayed rapidly thereafter. Treatment with the protein synthesis inhibitor, cycloheximide (CHX), also caused induction of IS10a mRNA to comparable levels, but the IS10a mRNA continued to accumulate after 3 h of induction. In combination, CHX and SA led to a superinduction of IS10a mRNA levels that was also sustained. Half-maximal induction was evident at ca. 100–150 M SA. In addition to SA, induction of IS10a occurred to varying degrees upon treatment with acetylsalicylic acid, benzoic acid, 2,4-dichlorophenoxyacetic acid, methyl jasmonate, and hydrogen peroxide, whereas treatment with other compounds had no effect. The proteins encoded by IS10a and a second highly homologous cDNA show sequence similarity to UDP-glucose: flavonoid glucosyltransferases.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - 4HBA 4-hydroxybenzoic acid - aa amino acid - bp base pair - nt nucleotide - ASA acetyl salicylic acid - BA benzoic acid - CHX Cycloheximide - MJ methyl jasmonate - PCR polymerase chain reaction - SA salicylic acid - TMV tobacco mosaic virus     

Studies on the mechanisms of induction of N-nitrosodimethylamine demethylase by fasting,acetone, and ethanol

Previous work has shown that induction of a high-affinity NADPH-dependent nitrosodimethylamine demethylase (NDMAd) in liver microsomes occurs in rats due to fasting, ethanol consumption, and streptozotocin-induced diabetes. Several lines of observations suggest that this is due to the induction of specific cytochrome P-450 isozymes. Induction of P-450 species by ethanol has also been observed by other investigators. Since each of the above altered metabolic states has in common elevated levels of ketone bodies, the possible role of acetone, a known inducer of NDMAd, in the induction of the demethylase activity was investigated. Levels of endogenous acetone in fasted rats correlated (r = 0.72) with a three- to fourfold increase in NDMAd activity. However, a dose-response experiment showed endogenous levels of acetone to be capable of causing at most 40% of the induction in fasted rats. This suggests that other ketone bodies or factors may have contributed to the induction. The induction of NDMAd by ethanol was enhanced by alcohol dehydrogenase inhibitors pyrazole and acetaldehyde oxime, suggesting that ethanol, rather than its metabolites, was responsible for the induction.     

银杏愈伤组织诱导的多因子正交试验研究

采用正交试验设计法,研究了NAA、KT、2,4-D、蔗糖浓度和不同外植体类型等因素对银杏愈伤组织诱导的影响。结果表明:不同外植体类型对银杏愈伤组织诱导率影响最大,KT和NAA其次,2,4-D和蔗糖浓度最小。银杏愈伤组织诱导最佳培养基为MS+NAA 0.5 mg·L-1+KT 0.5 mg·L-1+蔗糖40 g·L-1,最佳外植体为茎段,其愈伤组织诱导率可达100%。     

Effect of chloramphenicol and cycloheximide on the induction of nitrate reductase and nitrite reductase in bean leaves

Summary In etiolated leaves of Phaseolus vulgaris L. cv. Prelude only low levels of NADH-nitrate oxidoreductase (E.C. 1.6.6.2; NAR) and reduced benzyl viologen-nitrite oxidoreductase (E.C. 1.6.6.4; NIR) could be detected, even in the presence of nitrate. When nitrate was available illumination of leaves of 10-day-old etiolated seedlings resulted in an induction of both NAR and NIR. In the absence of nitrate no induction of the enzymes took place, although greening of the leaves was normal. Chloramphenicol (CAP) and cycloheximide (CHI), applied at the beginning of the light period, inhibited the induction of both NAR and NIR. Administered after 24 h of illumination CHI still inhibited the induction of both enzymes whereas CAP was no longer inhibitory. The induction of NAR and NIR by nitrate in green leaves in light was inhibited by CHI but not by CAP. From these results it seems likely that both the enzymes NAR and NIR are synthesized on cytoplasmic ribosomes. Before the enzymes can be manufactured in the cytoplasm some chloroplast development is required.Abbreviations CAP chloramphenicol - CHI cycloheximide - G-6-P(-dh) glucose-6-phosphate (dehydrogenase) - NAR nitrate reductase - NIR nitrite reductase     

Regulation of amino acid transport in the renal epithelial cell line NBL-1

Summary The activities of the transport systems A, B° and X_AG- are induced by various forms of stress in renal epithelial cells. Amino acid deprivation induces System A and X_AG- in a protein-synthesis dependent process. In the case of System X_AG- evidence is presented that induction of transport does not involve an increase in the amount of mRNA for the transporter or of the amount of transport protein. Preliminary evidence for the existence of a novel glycoprotein which is induced in parallel to the induction of these transport systems is presented. It is suggested that the induction of amino acid transport proteins and of some of the so-called stress proteins may be triggered by a common molecular mechanism.     

Protein Kinase C Is Required for Induction of 2′,5′-Oligoadenylate Synthetases

Induction of the p40/46 and p69/71 isoforms of the 2′,5′-oligoadenylate (2-5A) synthetase by interferon-α (IFN-α) is variable among six different Burkitt lymphoma cell lines with Ramos cells expressing among the highest levels of these enzymes. Inhibitors of protein kinase C (PKC) block induction of mRNAs encoding both isoforms; however, induction of the p69/71 isoform is more sensitive to these inhibitors. Downregulation of PKC by prolonged treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) also blocks induction of 2-5A synthetase mRNAs and decreases both constitutive and IFN-α-induced enzymatic activity. Cotreatment of cells with TPA and IFN-α increases induction of 2-5A synthetase mRNAs above that seen in cells treated with IFN-α alone. IFN-α does not directly activate PKC-α or PKC-δ, the two most abundant PKC isoforms present in Ramos cells, suggesting that PKC activation by another signaling pathway is necessary for maximal induction of 2-5A synthetases by IFN-α.