Regulation of nitrile-hydratase synthesis in a Brevibacterium species

The regulation of nitrile-hydratase biosynthese was studied in Brevibacterium sp R 312. Enzyme biosynthesis was not influenced by any carbon and nitrogen source used in the growth medium. It was, however, repressed by amide and amide analogues. Acetamide repressed nitrile-hydratase biosynthesis and induced the wide-spectrum amidase. Therefore, it appeared reasonable to hypothesize a single repressor gene for the nitrile-hydratase/wide-spectrum amidase system.     

Stereoscopic back-scattered electron imaging of silver-stained proteins in nucleoli

By using simultaneously the AgNOR silver staining method, back-scattered electron imaging mode and stereo-tilt in scanning electron microscopy (SEM), it is possible to observe the nucleus through the cell surface, the nucleolus, and the tri-dimensional distribution of the AgNOR-associated acidic proteins. In C3H10T1:2 cells and their 7-12-dimethylbenz--anthracene-treated transformants, the staining demonstrates several intranucleolar silver-staining granules (SSG), surrounded by a weakly staining region. The SSG may represent the fibrillar center (FC) and the weakly staining region, the fibrillar dense component (FD). This component can link several SSG together to form a rope-like structure. In cells with no visible nucleolus and inactive nucleolar organizer regions (NORs) the silver-staining granules are less numerous, close together and the presumed fibrillar dense components are not visible. The SSG are located more peripheraly, and the weakly staining region and the rope-like structure are less prominent in control cell nucleoli than in transformed cells with a comparatively high rate of RNA synthesis.     

Neurophysiology of geniculate ganglion (facial nerve) taste systems: species comparisons

On the basis of various measures taken from geniculate gangliontaste neurons in four species, it was concluded that withineach species the neurons could be subdivided into distinct functionalgroups. In this report, the neural groups of different specieswere directly compared. Units from all four species were studiedwith a common test series of solutions in addition to otherstimuli. Since these stimuli were presented at the same concentrationsto all species, direct quantitative comparisons across specieswere possible for a wide range of chemical compounds. In addition,the neural groups were compared with respect to spontaneousand evoked activity measures, latency to electrical stimulation,and receptive field characteristics. These neurophysiologicaldata suggest a basic model of four distinct subgroups: acidunits, salt units, amino acid units, and X units.     

Inheritance of cellulose- and lignin-degrading ability as well as endoglucanase isozyme pattern in Dichomitus squalens

Summary The progeny of Dichomitus squalens CBS-432-34 is heterogeneous with respect to specific growth rate on glucose, cellulolytic ([U¹⁴C]cellulose ¹⁴CO₂) and ligninolytic ([¹⁴C]synthetic lignin ¹⁴CO₂) activities with little correlation between these metric characters. Variations do not show clear-cut phenotypes but rather a continuous range between extreme values pointing to multigenic control of these characters. Most homocaryons showed decreased cellulolytic or ligninolytic activity compared to the parent dicaryon. However a few homocaryons were comparable or even superior to the parent dicaryon for ligninolytic or cellulolytic activity with no correlation between each factor. Strains with reduced cellulolytic activity and altered isozyme patterns of endoglucanases were isolated in the progeny of D. squalens CBS-432-34. While the parent strain produced three main endoglucanase multiple enzymes designated EnI, EnII and EnIII, several strains in the progeny produced a different multiple enzyme pattern. In contrast to the quantitative ability to degrade cellulose, multiple enzyme pattern variation in the progeny did not show continuous variations. characterization of heterocaryon phenotypes derived from Ien⁺ and Ien 1 homocaryons and first filial generation (f1) analysis showed that genetic control of the multiple enzyme pattern (Ien 1 phenotype) in D. squalens is complex. Offprint requests to: E. Odier     

Inhibition of nitric oxide synthesis increases mortality in Sindbis virus encephalitis.

Sindbis virus (SV) is an alphavirus that causes acute encephalomyelitis in mice. The outcome is determined by the strain of virus and by the age and genetic background of the host. The mortality rates after infection with NSV, a neurovirulent strain of SV, were as follows v: 81% (17 of 21) in BALB/cJ mice; 20% (4 of 20) in BALB/cByJ mice (P < 0.001); 100% in A/J, C57BL/6J, SJL, and DBA mice; and 79% (11 of 14) in immunodeficient scid/CB17 mice. Treatment with Nomega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthetase (NOS) inhibitor, increased mortality to 100% (P < 0.05) in NSV-infected BALB/cJ mice, to 95% (P < 0.001) in BALB/cByJ mice, and to 100% in scid/CB17 mice. BALB/cJ and BALB/cByJ mice had similar levels of inducible NOS mRNA in their brains, which were not affected by L-NAME or NSV infection. Brain NOS activity was similar in BALB/cJ and BALB/cByJ mice before and after infection and was markedly inhibited by L-NAME. NSV replication in the brains of BALB/cJ mice, BALB/cByJ mice, and mice treated with L-NAME was similar. Treatment of N18 neuroblastoma cells with NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside in vitro before infection increased cell viability at 42 to 48 h compared with untreated NSV-infected N18 cells with little effect on virus replication. These data suggest that NO protects mice from fatal encephalitis by a mechanism that does not directly involve the immune response or inhibition of virus growth but rather may enhance survival of the infected neuron until the immune response can control virus replication.     

Metabolite effectors for short-term nitrogen-dependent enhancement of phosphoenolpyruvate carboxylase activity and decrease of net sucrose synthesis in wheat leaves

It has been demonstrated previously that field pea (Pisum sativum L. cv. Express) grown in hydroponic culture on a complete nutrient solution with low NH₄⁺ concentrations (<0.5 mM) will produce a larger than normal proliferation of nodules. Peas grown in the absence of mineral N in hydroponic culture have been shown to rapidly autoregulate nodulation, forming a static nodule number by 14 to 21 days after planting. The present study further characterizes the effect of NH₄⁺ concentration in hydroponic culture on nodulation and nodule growth. Peas were grown continually for 4 weeks at NH₄⁺ concentrations that were autoregulatory (0.0 mM), stimulatory (0.2 mM) or inhibitory (1.0 mM), or peas were transferred between autoregulatory or NH₄⁺ inhibited and stimulatory solutions after 2 weeks. The peas nodulated as expected when grown under constant autoregulatory, stimulatory or inhibitory concentrations of NH₄⁺. When peas were transferred from the inhibitory (1.0 mM) to the stimulatory solution (0.2 mM) a massive proliferation of nodule primordia over the entire root system was observed within 3 days of the transfer. When they were transferred from the autoregulatory (0.0 mM) to the stimulatory (0.2 mM) solution a 10-day delay occurred before a proliferation in nodule primordia occurred at distal regions of the root system. These findings support our hypothesis that low concentrations (<1.0 mM) of NH₄⁺ in hydroponic culture cause a suppression of autoregulation in pea. In addition, the temporal and spatial differences in nodule proliferation between transfer treatments demonstrate at a whole plant level that autoregulation and NH₄⁺ inhibition suppress early nodule development via different mechanisms.     

Purification,crystallization, and preliminary X-ray studies on the rhizome lectin from stinging nettle and its complex with NN′N″-triacetylchitotriose

Single crystals were grown from affinity-purified stinging nettle lectin and from its complex with the specific trisaccharide NN′N″ -triacetylchitotriose by vapor diffusion at room temperature. The lectin crystallizes in space group P2₁2₁2₁ with unit cell dimensions a = 54.3 (1) Å, b = 62.2 (1) Å, and c = 92.4 (2) Å, and diffracts to 3.0 Å resolution. The asymmetric unit contains three lectin monomers. The crystals of the lectin-trisaccharide complex have space group P2₁2₁2₁ with cell constants a = 37.69 (4) Å, b = 48.97 (6) Å, and c = 57.32 (4) Å. These crystals diffract to at least 2.0 Å resolution and the asymmetric unit contains one lectin monomer. A three-dimensional X-ray structure determination is on its way. © 1993 Wiley-Liss, Inc.     

New Isopropyl Chromone and Flavanone Glucoside Compounds from the Leaves of Syzygium cerasiforme (Blume) Merr. & L.M.Perry and Their Inhibition of Nitric Oxide Production

A new isopropyl chromone ( 1 ) and a new flavanone glucoside ( 2 ) together with eleven known compounds ( 3–13 ) were isolated from the leaves of Syzygium cerasiforme (Blume) Merr. & L.M.Perry. Their structures were elucidated as 5,7-dihydroxy-2-isopropyl-6,8-dimethyl-4H-chromen-4-one ( 1 ), 5,7-dihydroxyflavanone 7-O-β-D-(6′′-O-galloylglucopyranoside) ( 2 ), strobopinin ( 3 ), demethoxymatteucinol ( 4 ), pinocembrin-7-O-β-D-glucopyranoside ( 5 ), (2S)-hydroxynaringenin-7-O-β-D-glucopyranoside ( 6 ), afzelin ( 7 ), quercetin ( 8 ), kaplanin ( 9 ), endoperoxide G3 ( 10 ), grasshopper ( 11 ), vomifoliol ( 12 ), litseagermacrane ( 13 ) by the analysis of HR-ESI-MS, NMR, and CD spectral data. Compounds 1 , 2 , 5 , 6 and 10 inhibited NO production on LPS-activated RAW264.7 cells with IC₅₀ values of 12.28±1.15, 8.52±1.62, 7.68±0.87, 9.67±0.57, and 6.69±0.34 μM, respectively, while the IC₅₀ values of the other compounds ranging from 33.38±0.78 to 86.51±2.98 μM, compared to that of the positive control, N^G-monomethyl-L-arginine acetate (L-NMMA) with an IC₅₀ value of 32.50±1.00 μM.     

Chemical Profile and Biological Activities of Fungal Strains Isolated from Piper nigrum Roots: Experimental and Computational Approaches

The current report describes the chemical investigation and biological activity of extracts produced by three fungal strains Fusarium oxysporum, Penicillium simplicissimum, and Fusarium proliferatum isolated from the roots of Piper nigrum L. growing in Vietnam. These fungi were namely determined by morphological and DNA analyses. GC/MS identification revealed that the EtOAc extracts of these fungi were associated with the presence of saturated and unsaturated fatty acids. These EtOAc extracts showed cytotoxicity towards cancer cell lines HepG2, inhibited various microbacterial organisms, especially fungus Aspergillus niger and yeast Candida albicans (the MIC values of 50–100 μg/mL). In α-glucosidase inhibitory assay, they induced the IC₅₀ values of 1.00-2.53 μg/mL were better than positive control acarbose (169.80 μg/mL). The EtOAc extract of F. oxysporum also showed strong anti-inflammatory activity against NO production and PGE-2 level. Four major compounds linoleic acid (37.346 %), oleic acid (27.520 %), palmitic acid (25.547 %), and stearic acid (7.030 %) from the EtOAc extract of F. oxysporum were selective in molecular docking study, by which linoleic and oleic acids showed higher binding affinity towards α-glucosidase than palmitic and stearic acids. In subsequent docking assay with inducible nitric oxide synthase (iNOS), palmitic acid, oleic acid and linoleic acid could be moderate inhibitors.