Synthesis and characterization of gold(III) complexes of 1,4-benzodiazepin-2-ones. Crystal structure of trichloro-[7-chloro-1-(cyclopropylmethyl)-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one]gold(III)

The reaction of gold(III) chloride with several 1,4-benzodiazepin-2-ones, L, gives 1:1 adducts, (L)AuCl₃*, which were characterized by IR, Raman and ¹H NMR spectroscopy. In the title compound the coordination of the ligand, ascertained through a X-ray structure determination, was shown to occur through the 4-nitrogen atom.     

Identification of different isoforms of eEF1A in the nuclear fraction of human T-lymphoblastic cancer cell line specifically binding to aptameric cytotoxic GT oligomers.

GT oligomers, showing a dose-dependent cytotoxic effect on a variety of human cancer cell lines, but not on normal human lymphocytes, recognize and form complexes with nuclear proteins. By working with human T-lymphoblastic CCRF-CEM cells and by using MS and SouthWestern blotting, we identified eukaryotic elongation factor 1 alpha (eEF1A) as the main nuclear protein that specifically recognizes these oligonucleotides. Western blotting and supershift assays confirmed the nature of this protein and its involvement in forming a cytotoxicity-related complex (CRC). On the contrary, normal human lymphocytes did not show nuclear proteins able to produce CRC in a SouthWestern blot. Comparative bidimensional PAGE and Western-blotting analysis for eEF1A revealed the presence of a specific cluster of spots, focusing at more basic pH, in nuclear extracts of cancer cells but absent in those of normal lymphocytes. Moreover, a bidimensional PAGE SouthWestern blot demonstrated that cytotoxic GT oligomers selectively recognized the more basic eEF1A isoform expressed only in cancer cells. These results suggest the involvement of eEF1A, associated with the nuclear-enriched fraction, in the growth and maintenance of tumour cells, possibly modulated by post-translational processing of the polypeptide chain.     

ROLE OF THE NITROGEN-FIXING BACTERIAL MICROFLORA IN THE EPIPHYTISM OF TILLANDSIA (BROMELIACEAE)

Nitrogen-fixing activity in the phyllosphere of 12 species of Tillandsia from different Mexican habitats was evaluated by the acetylene reduction assay, and nitrogen-fixing microorganisms were isolated and characterized. The leaves from eight of the 12 Tillandsia species examined exhibited nitrogenase activity in enrichment cultures. Among the microorganisms implicated—Agrobacterium, Bacillus, Erwinia, Pseudomonas, Rahnella, Vibrio, and Xanthomonas—only Bacillus megatherium reduced acetylene in pure culture. Our findings suggest that nitrogen fixation in the phyllosphere of the sampled epiphytes occurs under suitable conditions and that most of the bacteria involved are primarily soil and water inhabitants. The results also suggest a relationship between the composition of the nitrogen-fixing microbial communities grown on the leaf and the different development of the leaf area in Tillandsia due to the aerial components (wings) of the trichomes.     

A wind tunnel comparison of the rotorod and samplair pollen samplers

Summary The relative sampling efficiency of the Samplair (Allergenco Inc.) and Rotorod samplers (Sampling Technologies Inc.) were compared for different conifer pollen sizes and at different wind speeds. The wind tunnel experiments conducted with the two samplers are valid for the range of wind speeds and conifer pollen types which might be expected in seed orchards in Canada. A Quadratic relationship was established between the two samplers which revealed a decrease in relative efficiency on the part of the Samplair as compared to the Rotorod at wind speeds less than 5 m/s. An apparent increase in the efficiency of the samplair at higher wind speeds resulted from a decrease in the sampling ability of the rotorod.     

Benzenepropanoic acids containing chromanone or naphthalenone moieties are potent and orally active leukotriene B4 antagonists

Systematic structural modification of peptidoleukotriene antagonists of the o-hydroxyacetophenone class has led to the discovery of certain [[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]alkyl]benzenepropanoic acids and related compounds (7), which appear to be potent and selective antagonists of the proinflammatory mediator leukotriene B₄.     

SO2-induced decrease in photosynthetic activity in two barley cultivars. Evidence against specific damage at the protein-pigment complex level

This research investigated the SO₂-induced effects on photosynthetic apparatus in two barley (Hordeum vulgare L.) cultivars (cv), Panda and Express. Following a chronic treatment with SO₂ (80 ppb, 75 d) neither cv showed any visible signs of injury or chlorosis on leaf surfaces, while a significant reduction in A_max and G_w was detected in both cvs, although to different extents. Thylakoids of SO₂-treated plants showed a decrease in the electron transport activity at the whole chain, photosystem II (PSII) and photosystem I (PSI) level in both cvs. The high performance liquid chromatography (HPLC) analysis of leaf pigments revealed a significant decrease in both cvs, more pronounced in Panda than in Express. Deriphat-polyacrilamide gel electrophoresis (Deriphat-PAGE) and two dimensional (2-D) electrophoretic analyses of the pigment-protein complexes did not show differences in SO₂-treated samples of either cv. HPLC analysis of the green bands also showed no differences in the pigment content of fumigated samples of either cv, except for a decrease in β-carotene content and xanthophyll cycle pigment (VAZ) content respectively at band 1 (PSI) and band 5 (minor light-harvesting polypeptides of PSII) level in cv Panda, where the de-epoxidation index (DEP) significantly increased, while in Express, an increase in VAZ content and DEP value of band 5 was observed. These results suggest that the decrease in the photosynthetic activity can be ascribed, in addition to stomata closure induced by SO₂, to a generalised, rather than specific, pollutant effect on photosynthetic apparatus, which could be interpreted as an adaptation to the adverse environment.     

Large-scale production of peptides using the solid phase continuous flow method. Part 2: preparative synthesis of a 26-mer peptide thrombin inhibitor

A preparative method for the preparation of large peptides is described. An advantageous theoretical weight of peptide/weight of starting resin ratio (tP_w/R_w) of about 0.3 was successfully experimented. The esterification of the first amino acid was realized with a racemization of less than 1%. The study of the coupling conditions led to the use of a diluted acylating mixture that allowed a 56% consumption of the amino acid derivatives (percentage use of amino acids) introduced in the synthesis. The cost analysis of the synthesis showed that the recovery of the amino acid derivatives was not worthwhile. © 1998 European Peptide Society and John Wiley & Sons, Ltd.     

Identification and distribution of nitric oxide synthase in the brain of adult Antarctic teleosts

We investigated the presence of nitric oxide synthase (NOS) in brain of adult Antarctic teleosts by indirect immunofluorescence technique using a synthetic rat neuronal NOS (nNOS) antibody. The following species were examined: Trematomus bernacchii, Gymnodraco acuticeps, Histiodraco velifer, Cygnodraco mawsoni (haemoglobin-rich), Chionodraco hamatus and Pagetopsis macropterus (haemoglobin-free). Immunoreactive cell bodies were localized in dorsal telencephalon, in hypothalamus, in optic tectum of the mesencephalon as well as in Purkinje cells of the cerebellum. No differences were observed in the localization of the nNOS immunopositivity in the Antarctic teleosts brains examined and NOS distribution was similar to that described in other teleosts, suggesting that nitric oxide (NO) may also function as a neurotransmitter in the brain of Antarctic teleosts. A strong immunopositivity was observed in the cerebral blood vessels of the icefishes suggesting that NO may play a pivotal role in the regulation of the cerebral blood flow especially in these haemoglobin-free species.