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101.
Márcia Camargo-De-Morais Marta De Freitas Angela G. De Mattos Nádia Schröder Ana C. Zilles Carla S. F. Lisboa Nice Arteni Armando Barlem Rejane Schierholt Guilherme Zwetsch Carlos A. B. Souza Regina Pessoa-Pureur Carlos A. Netto 《Neurochemical research》1996,21(5):595-602
Neurofilaments subunits (NF-H, NF-M, NF-L) and glial fibrillary acidic protein (GFAP) were investigated in the hippocampus
of rats after distinct periods of reperfusion (1 to 15 days) following 20 min of transient global forebrain ischemia in the
rat. In vitro [14Ca]leucine incorporation was not altered until 48 h after the ischemic insult, however concentration of intermediate filament
subunits significantly decreased in this period. Three days after the insult, leucine incorporation significantly increased
while the concentration NF-H, NF-M, and NF-L were still diminished after 15 days of reperfusion. In vitro incorporation of32P into NF-M and NF-L suffered immediately after ischemia, but returned to control values after two days of reperfusion. GFAP
levels decreased immediately after ischemia but quickly recovered and significantly peaked from 7 to 10 days after the insult.
These results suggest that transient ischemia followed by reperfusion causes proteolysis of intermediate filaments in the
hippocampus, and that proteolysis could be facilitated by diminished phosphorylation levels of NF-M and NF-L. 相似文献
102.
“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species
B. Nicolaus Licia Lama Enrico Esposito Maria Cristina Manca Guido di Prisco Agata Gambacorta 《Polar Biology》1996,16(2):101-104
A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature
of 63°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular
alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572).
Received : 3 February 1995/Accepted : 12 May 1995 相似文献
103.
J. Miranda J. Membrillo-Hernández M. L. Tabche M. Soberón 《Applied microbiology and biotechnology》1996,45(1-2):182-188
A method to isolate mutants with derepressed expression of cytochrome oxidases and better symbiotic performance is presented.
A mutant of Rhizobium etli, CFN030, isolated by its azide-resistant phenotype, was obtained by transposon Tn5-mob mutagenesis. This mutant has a derepressed expression of cytochrome aa3, higher respiratory activities when cultured microaerobically and an improved symbiotic nitrogen fixation capacity. This
phenotype was similar to the previously described mutant CFN037, which was isolated by its increased capacity to oxidize N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) [Soberón M et al. (1990) J Bacteriol 172:1676–1680]. We show here that although both mutants have
a similar symbiotic phenotype, they are affected in different genes. Strain CFN030 has the Tn5 inserted in the chromosome while in strain CFN037 the transposon was located in plasmid b. Cytochrome spectral analysis of
both mutant strains in the post-exponential phase of growth, showed the expression of an additional terminal oxidase (cbb3) that is not expressed in the wild-type strain.
Received: 10 April 1995/Received revision: 21 August 1995/Accepted: 7 September1995 相似文献
104.
Ana Maria Landeira-Fernandez Maricilia S. Costa Leopolde de Meis 《Bioscience reports》1996,16(6):439-451
Vesicles derived from maize roots retain a membrane bound H+-ATPase that is able to pump H+ at the expense of ATP hydrolysis. In this work it is shown that heparin, fucose-branched chondroitin sulfate and dextran sulfate 8000 promote a shift of the H+-ATPase optimum pH from 6.0 to 7.0. This shift is a result of a dual effect of the sulfated polysaccharides, inhibition at pH 6.0 and activation at pH 7.O. At pH 6.0 dextran 8000 promotes an increase of the apparent Km for ATP from 0.28 to 0.95 mM and a decrease of the Vmax from 14.5 to 7.1 mol Pi/mg · 30 min–1. At pH 7.0 dextran 8000 promotes an increase in Vmax from 6.7 to 11.7 mol Pi/mg · 30 min–1. In the presence of lysophosphatidylcholine the inhibitory effect of the sulfated polysaccharides observed at pH 6.0 was not altered but the activation of pH 7.0 decreased. It was found that in the presence of sulfated polysaccharides the ATPase became highly sensitive to K+ and Na+. Both the inhibition at pH 6.0 and the activation promoted by the polysaccharide were antagonized by monovalent cations (K+>Na+Li+).Abbreviations Mops
4-morpholinopropanesulfonic acid
- EDTA
ethylenediaminetetraacetic acid
- ACMA
9-amino-6-chloro-2-methoxyacridine
- FCCP
carbonyl cyanide p(trifluoromethoxy)-phenylhyrazone 相似文献
105.
Results are presented on the phytoplankton species compositionand abundance from bottle samples collected in September 1989near the confluence of the Brazil and Malvinas currents offArgentina. The phytoplankton assemblages were dominated by diatomsand dinoflagellates. A surface diatom bloom was found alongthe west side of the Brazil Current, and was dominated by Thalassiosiradelicatula Ostenfeld emend. Hasle (cell numbers up to 5.5 x105 cells 11) The bloom was associated with strong temperaturegradients separating Brazil and Malvinas waters, and with thepresence of a cyclonic eddy near the confluence of the currents.These features were detected in satellite imagery coincidentwith the in situ sampling dates. 相似文献
106.
Figueiredo A. Cristina Almendra M. João Barroso José G. Scheffer Johannes J. C. 《Biotechnology letters》1996,18(8):863-868
The transformation capacity of Achillea millefolium L. ssp. millefolium (yarrow) cell suspension cultures was investigated using geraniol (50mg/l) and borneol, menthol, thymol and farnesols (25mg/l) as substrates. Apart from converting these substrates into several biotransformation products, the cell suspension cultures were also able to glycosylate both the substrates and the biotransformation products. aa]Key Words bb]Achillea millefolium L. ssp. millefolium bb]Yarrow bb]Compositae bb]Biotransformation bb]Glycosylation bb]Geraniol bb]Borneol bb]Menthol bb]Thymol bb]Farnesols 相似文献
107.
Lino Piccinini Paola Borella Annalisa Bargellini Cristina Incerti Medici Alessandra Zoboli 《Biological trace element research》1996,51(1):23-30
The purpose of our study was to investigate the relationship between plasma and hair levels of Se, Zn, and Cu, and cancer.
We selected a total of 66 patients affected by either breast (38) or lung (28) cancer. They entered into the study at the
onset of disease, and before any chemical or radiotherapy. Controls were randomly selected among healthy people and were matched
for sex, age, smoking habits, and residence. In the group of breast cancer, a significant decrease in hair Se was found compared
to controls (p<0.01), whereas plasma Se was only slightly decreased. No difference between cases and controls was detected in both hair
and plasma levels of Zn and Cu. Subjects who developed lung cancer were significantly lower in hair Zn (p<0.05) and Cu (p<0.01) than controls, whereas there was no difference with regard to Se. In addition, plasma Cu of these patients was increased
as compared to controls. 相似文献
108.
We have investigated the substrate subsite recognition requirement of the xyloglucan endo-transglycosylase/xyloglucan-specific endo-(14)--d-glucanase (NXET) from the cotyledons of nasturtium seedlings. Seed xyloglucans are composed almost entirely of the Glc4 subunits XXXG, XLXG, XXLG and XLLG, where G represents an unsubstituted glucose residue, X a xylose-substituted glucose residue and L a galactosyl-xylose-substituted glucose residue. Thus in the xyloglucan sequence shown below, the xylose (Xyl) residues at the backbone glucose (Glc) residues numbered — 3,— 2, + 2 and + 3 may be galactose-substituted, and NXET cleaves between the unsubstituted glucose at — 1 and the xylose-substituted glucose at + 1, which never carries a galactosyl substituent. We have isolated the xyloglucan oligosaccharides XXXGXXXG and XLLGXLLG from NXET digests of tamarind seed xyloglucan, have modified them enzymatically using a pure xyloglucan oligosaccharide-specific -xylosidase from nasturtium seeds to give GXXGXXXG and GLLGXLLG, and have identified and compared the products of NXET action on XXXGXXXG, GXXGXXXG, XLLGXLLG and GLLGXLLG. We have also compared the molar proportions of XXXG, XLXG, XXLG and XLLG in native tamarind and nasturtium seed xyloglucans with those in NXET digests of these polysaccharides. Using these and existing data we have demonstrated that NXET action does not require xylosesubstitution at glucose residues — 4, — 2, + 1 and + 3 and that xylose substitution at + 2, is a requirement. There may also be a requirement for xylose substitution at — 3. We have demonstrated also that galactosyl substitution of a xylose residue at + 1 prevents, and at — 2 modifies, chain-cleavage. A partial model for the minimum substrate binding requirement of NXET is proposed.Abbreviations G
unsubstituted glucose residue
- X
xylose-substituted glucose residue
- L
galactosylxylose-substituted glucose residue
- F
fucosyl-galactosylxylose-substituted glucose residue
- Gal
galactose
- Glc
glucose
- HPAE
high-performance anion-exchange chromatography
- NXET
nasturtium xyloglucan endo-transglycosylase or xyloglucan-specific endo-(14)--d-glucanase
- Xyl
xylose
This work was funded jointly by Unilever UK and the Department of Trade and Industry (UK) via the LINK initiative Agro-Food Quality. 相似文献
109.
F. J. L. Aragão L. M. G. Barros A. C. M. Brasileiro S. G. Ribeiro F. D. Smith J. C. Sanford J. C. Faria E. L. Rech 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(1-2):142-150
Exploiting the biolistic process we have generated stable transgenic bean (Phaseolus vulgaris L.) plants with unlinked and linked foreign genes. Co-transformation was conducted using plasmid constructions containing a fusion of the gus and neo genes, which were co-introduced with the methionine-rich 2S albumin gene isolated from the Brazil nut and the antisense sequence of AC1, AC2, AC3 and BC1 genes from the bean golden mosaic geminivirus. The results revealed a co-transformation frequency ranging from 40% to 50% when using unlinked genes and 100% for linked genes. The introduced foreign genes were inherited in a Mendelian fashion in most of the transgenic bean lines. PCR and Southern blot hybridization confirmed the integration of the foreign genes in the plant genome. 相似文献
110.
Ana Cristina Gomes da Cunha Manuel Fernandes Ferreira 《Plant Cell, Tissue and Organ Culture》1996,47(1):1-8
The effects of plant growth regulators (PGR) on calli induction, morphogenesis and somatic embryogenesis of flax were studied. The organogenic and callus formation capacity were assessed for different types of source explants. Root and shoot explants were equally good material for calli production but the former produced calli without shoot regeneration capacity. Under the experimental conditions tested, 2,4-dichlorophenoxyacetic acid (2,4-D) + zeatin was the most efficient PGR combination on calli induction and biomass production. The calli were green but with no rhizogenic capacity. In contrast, and at similar concentrations, indole-3-butyric acid (IBA) + kinetin induced white or pale green friable calli with a good root regeneration capacity (60%). A factorial experiment with different combinations of 2,4-D + zeatin + gibberellic acid (GA3) levels revealed that the direction of explant differentiation was determined by specific PGR interactions and concentrations. The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l?1 in the induction medium. The induction and development of somatic embryos from flax explants was possible in a range of 2,4-D + zeatin concentrations surrounding 0.4 mg l?1 2,4-D and 1.6 mg l?1 zeatin, the most efficient growth regulator combination. 相似文献