Identification and characterization of flavonoids in the root exudate of Robinia pseudoacacia

 Eight compounds exuded from young roots of black locust (Robinia pseudoacacia) were separated by two-dimensional HPTLC, by HPLC and GC, and were identified by spectroscopic methods (ultraviolet/visible spectroscopy and mass spectrometry) as 4′,7-dihydroxyflavone, apigenin, naringenin, chrysoeriol and isoliquiritigenin. Structural assignments were confirmed by comparison with authentic standards. The capacity to induce β-galactosidase activity in Rhizobium sp. NGR234 containing a nod box::lacZ fusion on plasmid pA27 identified these flavonoids and the chalcone as nod gene inducers. This indicates the important role of these compounds in nodulation of this legume tree. Received: 26 July 1996 / Accepted: 9 September 1996     

In vitro induction of bilirubin conjugation in primary rat hepatocyte culture

UDP-glucuronosyltransferase (UGT1A1) is a critical enzyme in the elimination of bilirubin. The aim of our study was to investigate bilirubin conjugation in primary rat hepatocyte culture and the in vitro inducibility of this isoenzyme by inducing compounds of different classes: dexamethasone, clofibrate, rifampicin, and methylcholanthrene. Hepatocytes exhibited a marked decline in UGT1A1 activity in the first 4 h of culturing (10% of initial activity) and the recovery took 72 h. Immunoblot analysis proved that the loss of enzyme activity was associated with the decrease of protein concentration. Marked induction was detected in the cases of dexamethasone, clofibrate, and rifampicin treatments for 96 h both in enzyme activity (178, 176, and 168%) and in UGT1A1 protein level (362, 328, and 250%). The effects of dexamethasone and clofibrate were additive (210%). Methylcholanthrene had no influence on bilirubin conjugation in our system.     

农杆菌介导的高效玉米遗传转化体系的建立

为了建立玉米高频再生及高效遗传转化体系, 对影响玉米胚性愈伤组织诱导的11个因素及影响胚性愈伤分化的9个因素用正交实验方法进行研究。结果显示, 基因型对胚性愈伤诱导有极显著影响。6-BA、培养基、AgNO3、2,4-D、ABA对胚性愈伤诱导的影响达到显著水平。多重比较分析显示ABA 2 mg/L每间隔1代添加对胚性愈伤诱导率有显著影响。在影响分化的因素中, 基因型和6-BA浓度表现出极强的主效应, NAA、培养基、KT、2,4-D对分化产生显著影响。Southern blotting 分析表明, 25 mg/L潮霉素选择压下抗性愈伤率作为转化体系优化指标是可靠的。在影响转化效率的因素中, acetosyringone (AS)使用浓度因基因型不同而表现出敏感度差异, 共培养温度24~25℃、农杆菌浓度和浸泡时间0.7 OD×15 min, 以及pH值5.5~6.2是最高转化率的优选组合。在整合后的玉米遗传转化体系中, 黄早4和综31自交系以抗性愈伤率为指标的GUS基因稳定转化率分别达到48.6%和46.2%。     

Use of the multi-allelic self-incompatibility gene in apple to assess homozygocity in shoots obtained through haploid induction

 To obtain homozygous genotypes of apple, we have induced haploid development of either the female or the male gametes by parthenogenesis in situ and anther culture, respectively. Of the shoots obtained, which were mainly of a non-haploid nature, some could be derived from fertilised egg cells or from sporophytic anther tissue. In order to select the shoots having a true haploid origin, and thus homozygotes, we decided to use the single multi-allelic self-incompatibility gene as a molecular marker to discriminate homozygous from heterozygous individuals. The rationale behind this approach was that diploid apple cultivars contain 2 different alleles of the S-gene and therefore the haploid induced shoots obtained from them should have only one of the alleles of the single parent. The parental cultivars used were ‘Idared’ (parthenogenesis in situ) and ‘Braeburn’ (androgenesis), and their S-genotypes were known, except for 1 of the ‘Braeburn’S-alleles. To stimulate parthenogenetic development ‘Idared’ styles were pollinated with irradiated ‘Baskatong’ pollen, the S-alleles of the latter (2n) cultivar were also unknown. The cloning and sequence analysis of these 3 unidentified S-alleles, 1 from ‘Braeburn’ and 2 from ‘Baskatong’ is described, and we show that they correspond to the S ₂₄ -, S ₂₆ - and S ₂₇ -alleles. We have optimised a method for analysis of the S-alleles of ‘Idared/Baskatong’- or ‘Braeburn’-derived in vitro plant tissues and have shown that this approach can be applied for the screening of the in vitro shoots for their haploid origin. Received: 18 August 1997 / Accepted: 10 September 1997     

Assessment of the genotoxic potential of Hoechst 33342, SYBR-14 and PI using the SOS ChromoTest™

Abstract

Fluorochromes in combination with flow cytometry can be used for laboratory assessment of semen quality in humans and domestic animals. Some studies have reported the potential toxicity of these fluorochromes toward the cells analyzed, but not toward the laboratory technician who operates the analytical instrument. We tested the genotoxic potential of three fluorochromes, SYBR-14, propidium iodide, and Hoechst 33342, using the colorimetric SOS ChromoTest^?. The test revealed no genotoxic potential for any of the three fluorochromes within the dilution ranges investigated. We conclude that occasional direct contact with these fluorescent probes does not necessarily pose a genotoxic hazard.     

Pharmacokinetic,metabolic stability,plasma protein binding and CYP450s inhibition/induction assessment studies of N-(2-pyridylmethyl)-2-hydroxiymethyl-1-pyrrolidinyl-4-(3-chloro-4-methoxy-benzylamino)-5-pyrimidine-carboxamide as potential type 5 phosphodiesterase inhibitors

N-(2-pyridylmethyl)-2-hydroxiymethyl-1-pyrrolidinyl-4-(3-chloro-4-methoxy-benzylamino)-5-pyrimidine-carboxamide (NHPPC) is a new potential of type 5 phosphodiesterase (PDE5) inhibitors, synthesized from the avanafil analogue for the treatment of erectile dysfunction. The targets of this article were to assess plasma protein binding, liver microsomal metabolic stability, inhibition and induction on cytochrome P450 isozymes and the pharmacokinetics of NHPPC. Equilibrium dialysis technique was applied to determine Plasma protein binding (PPB) and NHPPC was evaluated in male Sprague–Dawley rats and Beagle dogs in vivo pharmacokinetic. The NHPPC was highly bound to plasma proteins in rats, dogs and human tested and the mean values for PPB rate were 96.2%, 99.6% and 99.4%, respectively. After in vitro liver microsomes incubated for 60?min, the percent remaining of NHPPC was 42.8%, 0.8% and 42.0% in rats, dogs and human, respectively. In vitro intrinsic clearance was found to be 0.0233, 0.1204 and 0.0214 mL/min/mg protein in rat, dog and human liver microsomes of NHPPC, respectively. NHPPC showed no significant inhibitory effects on major CYP450 enzymes, and had no significant induction potential on CYP1A2 and CYP3A4. Following oral administration in rats and dogs, t_max was 6 and 0.5?h, respectively. The clearance for NHPPC was 1.19 and 1.46?L/h/kg in rats and dogs, respectively. And absolute bioavailability in rat and dog were approximately 34.5% and 53.1%, respectively. These results showed that NHPPC has a good development prospect.     

衣原体调控宿主细胞凋亡的机制研究进展

衣原体是一类专性细胞内寄生的原核微生物,常引起性传播疾病、失明和肺炎等疾病。衣原体可能已经进化出调控宿主细胞的若干机制,通过改变宿主细胞蛋白位置,干扰宿主细胞凋亡信号通路等来抑制细胞凋亡,维持其自身的存活,核转录因子NF-κB也涉及到衣原体感染细胞凋亡抑制;衣原体可以经半胱氨酸蛋白酶依赖途径等机制诱导细胞凋亡,进而感染邻近细胞。     

Constitutive and inducible aspects of nitrate-nitrogen uptake by Chlamydomonas reinhardtii

Similarly to higher plant root systems, Chlamydomonas reinhardtii Dangeard (UTEX 90) cells exhibited biphasic NO₃^? uptake kinetics. The uptake pattern was similar in cells cultured in 10 mM NO₃^? (NO₃^?-grown), 0.25 mM NO₃^? (N-limited) or 10 mM NO₃^? followed by an 18-h period of N-deprivation (N-starved). In all cell types there was an apparent phase transition in uptake at 1.1 mM NO₃^?, although there were variations in the uptake V_max of both isotherms. The rate of uptake via isotherm 0 ([NO₃^?]<1.1 mM) in N-limited cells was higher than that of either NO₃^?-grown or N-starved cells. In contrast, NO₃^?-grown and N-limited cells exhibited comparable V_max values when supplied with 1.1 to 1.8 mM NO₃^? (isotherm 1). When supplied with 1.6 mM NO₃^?, both N-limited and N-starved cells exhibited enhanced linear uptake after 60 min of incubation. We ascribed this to an induction phenomenon. This trend was not observed when NO₃^?-grown cells were supplied with 1.6 mM NO₃^?, or when N-limited and N-starved cells were supplied with 0.6 mM NO₃^?. The ‘inducible’ aspect of uptake by N-limited cells was blocked by cycloheximide (10 mg l^?1), but not by actinomycin D (5 mg l^?1), thus indicating the involvement of a translational or post-translational event. To investigate this phenomenon further, we analysed the cell proteins of N-limited cells supplied with either 0.6 or 1.6 mM NO₃^? for 90 min, using two-dimensional gel electrophoresis. Comparison of protein profiles enabled the identification of a single cell membrane-associated polypeptide (21 kDa, pI ca 5.5) and ten soluble fraction polypeptides (17–73 kDa, pI ca 5.0 to 7.1) unique to the high NO₃^? treatment. We propose that the ‘inducible’ portion of NO₃^? uptake may provide the means by which C. reinhardtii cells regulate uptake in accordance with assimilatory capacity.     

温度和光周期对绿盲蝽滞育诱导的影响

为了阐明环境因子对绿盲蝽Apolygus lucorum Meyer-Dür卵滞育诱导作用,测定了3个温度和6个光周期组合处理对绿肓蝽的滞育诱导和绿盲蝽光周期感应的敏感虫态,系统调查了绿肓蝽在不同温度和不同光照组合下所产卵的孵化率.结果表明:绿盲蝽的敏感虫态为1龄若虫;在17℃,20℃和23℃3个不同温度下,光照时间小...