The action of plant growth retardants on terpenoid biosynthesis

Summary The plant growth retardants (2-chloroethyl)-trimethylammonium chloride (CCC) and 2-isopropyl-4-(trimethylammoniumchloride)-5-methylphenyl-piperidine-1-carboxylate (AMO-1618) inhibit gibberellic-acid biosynthesis inFusarium moniliforme at the cyclisation of geranylgeraniol to (-)-kaurene, causing an accumulation of geranylgeraniol. The two inhibitors have no effect on the biosynthesis of ergosterol inF. moniliforme or sitosterol in barley seedlings.     

Degradation by and toxicity to bacteria of chlorinated phenols and benzenes,and hexachlorocyclohexane isomers

Mixed cultures degrading chlorinated benzenes, chlorinated phenols, or hexachlorocyclohexane (HCH) as the sole source of carbon and energy were obtained by enrichment from contaminated soil samples. Cultures which metabolized 3-chlorophenol (3-CP), 2,3-dichlorophenol (2,3-DCP), or 2,6-dichlorophenol (2,6-DCP) were able to utilize several other chlorinated compounds as substrates, whereas cultures enriched with 1,2,4,5-tetrachlorobenzene (1,2,4,5-TeCB), -HCH, or -HCH did not metabolize most of the other chlorinated congeners tested. Chloride release and growth rates with all four chlorinated phenols decreased with increasing initial substrate concentrations within the range of 30–250 mol liter^–1. Maximum chloride release was 3.8 mg liter^–1 corresponding to 35 mol liter^–1 trichlorophenol within 7 weeks. In contrast, the rate of metabolism of the nonphenolic compounds 1,2,4,5-TeCB, -HCH, or -HCH increased with increasing substrate concentrations. Initial concentrations of 750 mol liter^–1 -HCH or 1,2,4,5-TeCB were completely dechlorinated within 2 weeks. Because aqueous solubility and bioavailability of the chlorophenolic compounds is much higher than that of the nonphenolic compounds, it is suggested that the high bioavailability of the chlorophenolic compounds is the reason for the high toxicity of these substrates to the degrading cultures. In contrast, the low aqueous solubilities of the chlorinated benzenes and HCH-isomers caused consistently low concentrations in the medium, which were high enough to induce degradation but too low to damage the bacterial cells.Correspondence to: E. Lang     

Purification and characterization of a microsomal cytochrome P-450 with high activity of coumarin 7-hydroxylase from mouse liver

Phenobarbital-induced coumarin 7-hydroxylase is high in DBA/2J and low in C57BL/6N inbred mice; this genetic difference is encoded by the Coh locus on chromosome 7. The aim of this study was to develop an antibody specific for this cytochrome P-450 polymorphism. P-450 fractions, highly specific for phenobarbital-inducible coumarin 7-hydroxylase activity, were purified from DBA/2J and C57BL/6N mouse liver microsomes. Both proteins are 49 kDa, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Soret peaks of the reduced cytochrome . CO complexes are 451 nm. Reconstituted DBA/2J coumarin 7-hydroxylase activity exhibits a V twice as high as, and a Km value 10-fold less than, the reconstituted C57BL/6N activity. Antibodies were raised in rabbit. By Ouchterlony immunodiffusion, both antibodies show 100% cross-reactivity with DBA/2J and C57BL/6N microsomes and purified antigens. Yet, DBA/2J but not C57BL/6N 7-hydroxylase activity is inhibited by the antibody to DBA/2J P-450. Both DBA/2J and C57BL/6N activities are blocked by the antibody to C57BL/6N P-450. Neither antibody has any effect on liver microsomal d-benzphetamine N-demethylase, ethylmorphine N-demethylase, aminopyrine N-demethylase, 7-ethoxycoumarin O-deethylase, acetanilide 4-hydroxylase, or aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity. The DBA/2J protein most specific for phenobarbital-induced coumarin 7-hydroxylation is designated 'P-450Coh'. Anti-(P-450Coh) precipitates a relatively minor 49-kDa protein from detergent-solubilized microsomes and from in vitro translation of poly(A+)-enriched total RNA of phenobarbital-treated DBA/2J mouse liver, whereas the major phenobarbital-induced P-450 proteins exhibit a molecular mass of about 51 kDa. The immunoprecipitated translation products correspond to a messenger RNA of 2100 +/- 100 nucleotides.     

Two flavonol glycosides from Vancouveria hexandra.

In addition to two known glycosides, ikarisoside F and epimedin A, two new glycosides of a flavonol with a gamma, gamma-dimethylallyl group were isolated from the underground and the aerial parts of Vancouveria hexandra. The structures were determined to be des-O-methylanhydroicaritin 3,7-diglucoside and anhydroicaritin 3-glucosyl (1----3)rhamnoside-7-glucoside by means of spectral analysis.     

Marine biosurfactants. IV. Production,characterization and biosynthesis of an anionic glucose lipid from the marine bacterial strain MM1

Summary During screening for biosurfactants among marine, n-alkane-utilizing bacteria, low- and high-molecular surface-active substances were detected. The marine bacterial strain MM1 was found to synthesize a novel glycolipid that has not so far been cited in the literature. Both ¹H, ¹³C-nuclear magnetic resonance spectroscopic and positive ion fast atom bombardment mass spectrometer studies led to the identification of a glucose lipid consisting of four 3-OH-decanoic acids, which are linked together by ester bonds. The lipophilic moiety is coupled glycosidically with C-1 of glucose. The glucolipid reduced the surface tension from 72 mN/m to 30 mN/m while the minimum interfacial tension towards n-hexadecane was lowered to values smaller than 5 mN/m. Correspondence to: S. Lang     

Structural changes of ultraviolet-irradiated DNA derived from hydrodynamic measurements

The paper reports on sedimentation and viscosity measurements performed on ultraviolet-irradiated DNA from T7 phage and calf thymus. From the hydrodynamic data the relative changes in the mean molecular weight, radius of gyration, and effective Kuhn statistical segment length were calculated. The results show that ultraviolet irradiation (254 nm) leads to a significant decrease of the effective statistical segment length of DNA which may be due to small local helix kinks (produced by the generation of photodimers) and a local increase of chain flexibility. Alterations in the overall DNA conformation may be observed even at low fluences where the mean molecular weight almost stays constant. The locally distorted helix regions possibly may serve as recognition sites in the first step of excision repair.