Transition metal complexes bearing NHC ligands substituted with secondary polyfluoroalkyl groups.

Using three different approaches, racemic 1-(perfluoroalkyl)ethylamines were synthesized from perfluoroalkyl iodides or perfluoroalkanoic acids, and further transformed to the corresponding N,N'-disubstituted ethane-1,2-diimines and ethane-1,2-diamines as mixtures of diastereoisomers. Their cyclization afforded imidazolium or dihydroimidazolium salts, which led to silver or palladium complexes bearing NHC ligands substituted with secondary polyfluoroalkyl groups. The palladium complexes bearing a throwaway 3-chloropyridine ligand proved to be moderately active in the model Suzuki-Miyaura coupling.

Study of cytokinin metabolism using HPLC with radioisotope detection.

High performance liquid chromatography (HPLC) with an on-line flow-through radioactivity detector was used to monitor the metabolism of cytokinins ([3H]6-benzylaminopurine and [3H]6-benzylaminopurine riboside) after their incorporation into wheat seedlings. The production and conversion of individual metabolites was assayed within a short time interval (0.5-3 h). Extraction recoveries from plant tissue proved to be 85%. The uptake of both cytokinins was very rapid and differences in their metabolism were already perceptible after 30 min. The individual metabolites were identified as adenine (Ade), adenosine (Ado), benzyladenine-9-glucoside (BA-9G), 6-benzyladenine (BA) and benzyladenosine (BAR). The method is very fast, sensitive and very useful for metabolic studies. The detection limit was 40 pg (220 Bq) for BA at the level of 2 ng ml-1.

Capillary electrophoresis of cytokinins and cytokinin ribosides.

A CE separation of cytokinins and cytokinin ribosides and some other purine and pyrimidine bases has been developed. Two electrolyte systems have been tested: 150 mM phosphoric acid, pH 1.8 and 50 mM sodium dodecylsulphate + 20 mM borate, pH 9.2. The migration times were measured and the effects of the solute structures were discussed. Preliminary experiments with plant extracts have been performed to identify the cytokinins and their ribosides. Both the systems can be used, but 150 mM phosphoric acid is better suited for identification of cytokinins in plant extracts, as the electropherograms are subject to fewer interferences.

Partial auxin deprivation affects endogenous cytokinins in an auxin-dependent, cytokinin-independent tobacco cell strain.

The dynamics of individual endogenous cytokinins within the growth cycle (subculture interval) of an auxin-dependent and cytokinin-independent cell suspension culture ofNicotiana tabacum L. (strain VBI-0) were determined using high performance liquid chromatography and radioimmunoassay. In cells grown at an optimum auxin concentration the transient maxima of N(6)-(Δ(2)-isopentenyl)adenine and N(6)-(Δ(2)-isopentenyl)-adenosine correlated with the onset of cell division. Cultivation of the cells in a partially auxin-deprived medium resulted in ca. tenfold increase of all endogenous cytokinins. A very distinct maximum of N(6)-(Δ(2)-sopentenyl) adenine appeared at the beginning of subculture. This indicates that a lack of auxin induced an accumulation of cytokinins predominantly in the form of the free bases, which are physiologically more active than the corresponding ribosides.

Yersinia enterocolitica in water and foods.

Yersinia enterocolitica (Ye) isolates from water (367 strains) and different foods (114 strains) were typed serologically and biochemically. In some samples, especially of water, several Ye serotypes were found simultaneously. A noteworthy finding was Ye 03, biotype 4 in tinned meat paste that had already been on sale without, however, any case of diarrhoeal disease being reported in the particular district. The food and water strains included all Ye O-serotypes except 09. Numerous strains were untypable, probably possessing unknown O-antigens. Water isolates were less active biochemically than strains of identical serotypes from food sources.

A finding of Yersinia pseudotuberculosis in well water.

From a sample of non-treated, non chlorinated well water a Yersinia pseudotuberculosis II strain was isolated. The water had been apparently massively contaminated because the strain was isolated from 1 ml of the sample. The serotype II of Y. pseudotuberculosis occurs very rarely as aetiological agent of human and animal infections.