Conversion of Hypoxanthine Derivatives to Guanine Derivatives by Bacillus subtilis

By successive mutagenic treatments including transduction with bacteriophage SP–10, ultraviolet light irradiation and N-methyl-N′-nitro-N-nitrosoguanidine treatments, a mutant, strain No. 322, capable of converting exogenously supplemented hypoxanthine or inosine to guanine and guanosine, was derived from an adenine-less, IMP-producing mutant of Bacillus subtilis IAM 1145. Strain No. 322 was an adenine-leaky mutant lacking GMP-reductase, adenase, and 5′-nucleotidase. The strain effectively accumulated guanine and guanosine in the culture fluid, when grown in the presence of hypoxanthine or inosine, while it failed to convert exogenously supplemented IMP to the guanine derivatives.     

Detection of cytokinins in a seaweed extract

trans-Zeatin, trans-zeatin riboside, their dihydro derivatives, isopentenyladenine and isopentenyladenosine have been identified and quantified in Seasol, a commercial extract of Tasmanian Giant Bull kelp, Durvillea potatorum.     

Stereospecific microbiological 10-O-demethylation of R-(-)-10,11-dimethoxyaporphines

The microbiological O-dealkylation of (+) and (-) 10,11-dimethoxyaporphine and the corresponding N-n-propyl analog 10,11-dimethoxy-N-n-propylnoraporphine utilizing the fungus Cunninghamella elegans (ATCC 9245) was found to proceed with regioselectivity for the 10-position, and with a high degree of substrate stereospecificity for the 6a R(-)enantiomer. Only the (R) 10-demethylated products were isolated i.e. (R) iosapocodeine and (R) N-n-propylnor-isoapocodeine. The products were confirmed by comparison with their GC/MS spectra.     

Online Parallel Accumulation–Serial Fragmentation (PASEF) with a Novel Trapped Ion Mobility Mass Spectrometer

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Highlights

• •Online PASEF achieves greater than 100 MS/MS per second at full sensitivity.
• •Accurate label-free quantification of over 6000 proteins in 2 h.
• •High throughput demonstrated on 50 ng digests measured in 5 min.
• •High-precision determination of 100,000 peptide collisional cross sections.

     

Allelopathic Effect of Eucalyptus citriodora Essential Oil and Its Potential Use as Bioherbicide

The current study aimed to evaluate the negative allelopathic effect of Eucalyptus citriodora essential oil on some of the most noxious weeds in Algeria (Sinapis arvensis, Sonchus oleraceus, Xanthium strumarium and Avena fatua). Gas chromatography‐flame ionization detector (GC‐FID) and GC/mass spectrometry (MS) were used to define the chemical composition of the oil. Citronellal (64.7%) and citronellol (10.9%) were the major essential oil compounds. Three concentrations of the oil were used for laboratory (0.01, 0.02 and 0.03%) and greenhouse (1, 2 and 3%) experiments. Seed germination and seedling's growth were drastically reduced in response to the oil concentrations where at 0.01 and 0.02% the oil drastically affects the seed germination of the tested weeds and at 0.03% the oil suppresses completely the germination of S. arvensis. The oil also exhibited strong allelopathic effect on the 3 – 4 leaf‐stage plants 1 and 6 days after treatment. A completely death of S. arvensis, S. oleraceus and A. fatua and severe injuries on X. strumarium appeared at 3% of the oil. Chlorophyll content and membrane integrity were significantly affected after treatment of the plant weeds representing a severe reduction in total chlorophyll and cell membrane disruption. The study concludes that E. citriodora essential oil might has the potential use as bioherbicide and can constitute an alternative process of weed control.     

Chemical Variability of the Essential Oil of Pituranthos scoparius from Algeria

The chemical composition of 93 oil samples from the aerial parts of Pituranthos scoparius, harvested in three regions of Algeria, was investigated by GC‐FID, GC/MS and ¹³C‐NMR. Monoterpene hydrocarbons dominated in association with phenylpropanoids and a chemical variability was found highlighting three clusters. The composition of group I (36 samples) exhibited an atypical composition characterized by a very high contents of 6‐methoxyelemicine (13.0 – 59.6%), followed by sabinene (1.1 – 43.0%) and limonene (6.6 – 39.0%), while the samples of group II (12 samples) contained a high content of limonene (9.2 – 44.0%), followed by myristicine (0.0 – 29.4%) and a lower amount of sabinene (0.8 – 2.3%). Group III (45 samples) could be divided in two subgroups. Subgroup SGIIIA was characterized by a very high content of sabinene (28.0 – 55.6%), followed by elemicine (0.0 – 29.1%), while the samples belonging to SGIIIB were characterized by the lower content of sabinene (6.2 – 35.5%) and a significant content of myristicine (1.5 – 32.4%), α‐pinene (4.2 – 31.0%) and dill apiole (0.1 – 31.4%). Each harvested region was characterized by a different chemical composition.