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301.
María E. Jiménez-Capdeville Tomás A. Reader Eduardo Molina-Holgado Robert W. Dykes 《Neurochemical research》1996,21(1):1-6
This study examined the effects of a nerve transection on monoamine release from primary somatosensory cortex. The technique
of microdialysis was employed to sample extracellular levels of norepinephrine (NE), 3,4-dihydroxyphenylacetic acid (DOPAC),
5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in the barrel field of freely moving rats following the
surgical transection of the contralateral infraorbital nerve. Microdialysates obtained 3, 4, and 5 days after deafferentation
were analyzed using high-performance liquid chromatography with electrochemical detection. We found a significant increase
in the release of the dopamine metabolites, DOPAC and HVA from the deafferented cortex. Three days after deafferentation the
release of DOPAC was three-fold higher in the deafferented than in the control animals, and remained about 100% higher in
the next two days in this group of animals. The release of HVA showed a gradual increase following the deafferentation procedure,
since a 92% larger value on day 3 increased to a 338% difference on day 5. On the other hand, the release rate of NE and the
levels of the serotonin metabolite 5-HIAA were not significantly affected by the deafferentation procedure. These results
are discussed in the context of the possible participation of dopamine in the reorganization of the deafferented somatosensory
cortex. 相似文献
302.
The size relationship between the crown area of the lower canines (Cs), third (P3s) and fourth premolars (P4s), and first
molars (M1s) in hominids is examined by means of the regression analysis. The lower P3 seem to be under the influence of those
factors that control both the size of the anterior and posterior teeth, and the P4:P3 size ratio is related to the relative
size of the anterior and posterior dentitions. So, the P4>P3 sequence is associated with the megadontia and hipermegadontia
of the posterior teeth, whereas the expansion of the anterior teeth produces the P3>P4 sequence. We consider the P4:P3 size
ratio as an excellent indicator of the taxonomic and philogenetic status of fossil hominids. 相似文献
303.
A cladistic analysis of the genusAnisopappus (Asteraceae: Inuleae) has been undertaken. A hypothesis of species interrelationships in the genus is presented for the first time. The analysis also includedArctotis (Arctoteae), used as outgroup, and five additional genera from theInuleae: Geigeria, Calostephane, Asteriscus, Buphthalmum, Pulicaria, andInula. It is concluded thatAnisopappus is a monophyletic group situated at the base of the tribe, diagnosed by, e.g., their obtuse stylar sweeping-hairs. The species with acute sweeping-hairs were found to be derived within the genus. Problems concerning species delimitation, biogeography and character evolution in the genus are briefly discussed. 相似文献
304.
Nucleic acid scanning-by-hybridization of enterohemorrhagic Escherichia coli isolates using oligodeoxynucleotide arrays.
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Nucleic acid scanning by hybridization (NASBH) is a non-electrophoretic typing strategy that uses gridded oligonucleotides to reproducibly characterize arbitrarily amplified nucleic acid sequences. Membrane-bound arrays of terminally-degenerate oligonucleotides were hybridized to DNA amplification fingerprinting (DAF) products from enterohemorrhagic Escherichia coli O157:H7 isolates. Numerical and cluster analysis of 64 isolates, selected by DAF to represent a single dominant amplification type identified 14 hybridization types. Results show that NASBH is a powerful alternative for the identification of closely related bacteria, can be used successfully in epidemiological studies, and holds potential in general nucleic acid diagnostics. 相似文献
305.
Jesús Arellano Filiberto Vázquez Thelma Villegas Georgina Hernández 《Plant cell reports》1996,15(7):455-458
Summary The sesquiterpene quinone currently known as perezone is abundantly produced by the roots of Perezia cuernavacana. This compound is of biotechnological interest since it may be used as a pigment and has several pharmacological properties. In this work we demonstrate that perezone is also produced in transformed root cultures of P. cuernavacana. Hairy roots were induced by inoculation of internodal segments of sterile plants of P. cuernavacana with Agrobacterium rhizogenes AR12 strain. The axenic liquid MS medium cultures of the hairy roots isolated from the internodes showed active growth in the absence of growth regulators. The transformed nature of the tissue was confirmed by genomic integration (PCR and slot blot hybridization) and expression (enzyme activity) of the marker gus-gene. The production of perezone by a transformed root culture was evidenced by IR spectroscopy. Our results offer an alternative for enhanced production of perezone and represent an advantage over its extraction from natural plant populations which present problems in their agronomic culture. 相似文献
306.
M. T. Fernández-Espinar S. Vallés F. Piñaga J. A. Pérez-González D. Ramón 《Applied microbiology and biotechnology》1996,45(3):338-341
Using recombinant DNA techniques, an Aspergillus nidulans multicopy transformant for the gene xlnB coding for the minor X24 xylanase has been constructed. When grown on glucose as sole carbon source this transformant secretes 114 U of xylanase (mg
protein)-1. In this culture condition, X24 is the only xylanase secreted and the predominant protein in the culture filtrate. This strategy has been used to purify
the X24 enzyme to homogeneity. The purified xylanase showed a single band on sodium dodecyl sulphate/ polyacrylamide gel electrophoresis
with a molecular mass of 24 kDa and had an isoelectric point of approximately 3.5. The enzyme was a non-debranching endo-1,4-β-xylan
xylanohydrolase highly specific for xylans and showed optimal activity at pH 5.5 and 52°C. The X24 xylanase had a Michaelis constant, K
m, of 12.43 mg oat spelt xylan ml-1 and a V
max of 1639 μmol min-1 (mg protein)-1.
Received: 17 May 1995/Received last revision: 25 September 1995/Accepted: 29 September 1995 相似文献
307.
The effect of the addition of oleuropein (OLP) and NaCl on the growth and the DL-lactic acid production of Lactobacillus plantarum DSM 10492 has been investigated by using an unconventional medium. The growth of L. plantarum was not inhibited by the addition of increasing amounts of untreated OLP in the presence or absence of glucose. However,
bacterial cells grew in quantity slightly with OLP alone. The increased addition of NaCl was associated with a delay in growth.
Moreover, there was no growth with 8% NaCl. The addition of both NaCl and OLP resulted in growth inhibition, and the survival
of cells decreased strongly. The main fermentation product was DL-lactic acid, but acetic acid was also detected after a prolonged incubation. L. plantarum produced DL-lactic acid in the presence of OLP alone but its formation decreased with increasing levels of OLP. On the other hand, heat-treated
OLP had a bactericidal effect.
Received: 16 October 1995/Received last revision: 5 February 1996/Accepted: 12 February 1996 相似文献
308.
B. Szajáni Z. Buzás K. Dallmann I. Gimesi J. Krisch M. Tóth 《Applied microbiology and biotechnology》1996,46(2):122-125
Saccharomyces cerevisiae cells were immobilized on preformed cellulose beads by adsorption. The fermentation capacity of the immobilized yeast cells
was found to be practically independent of the hydrogen ion concentration between pH 3.1 and 6.25. The fermentation capacity
was maximal at 30 °C. The immobilized yeast cells were used for continuous production of ethanol in a fluidized-bead reactor.
The average values characteristic for the process were an ethanol concentration of 41.9±0.1 g l-1, a fermentation efficiency of 82.9±2.1% and a volumetric productivity of 3.94±0.52 g l-1 h-1.
Received: 9 October 1995/Accepted: 22 April 1996 相似文献
309.
Carole Mign Grard Prensier Agns Cornu Elisabeth Grenet 《Biology of the cell / under the auspices of the European Cell Biology Organization》1996,88(3):137-144
Summary— Arabinoxylans were localised by immunocytochemistry using polyclonal antibodies in the cell walls of the apical internode of maize after degradation in the rumen. In order to understand the significance of arabinoxylan in digestibility property, two lines of maize differing in digestibility were used. Wide variations in the intensity of labelling were observed in the four tissues studied (sclerenchyma, fibres, xylem and parenchyma) from the first hours of incubation in the rumen. Incubation time in the rumen greatly influences the intensity of labelling. 相似文献
310.
Jose-Emilio Mesonero María-Carmen Rodríguez Yoldi María-Jesús Rodríguez Yoldi 《Biological trace element research》1996,51(2):149-159
The element Cd is considered to have no biological function and is highly toxic to humans and animals. Toxic effects of this
metal upon cell membrane structure and function have been shown. On the other hand, Ca is an essential element in a wide variety
of cellular activities. The present study was initiated to research whether the interaction between Ca and Cd could affect
D-galactose absorption across the rabbit jejunum in vitro. In media with Ca2+, when CdCl2 was present at 0.5 or 1 mM, Cd was found to significantly reduce the sugar absorption. In Ca2+-free media, where CaCl2, was omitted and replaced isotonically with choline chloride, the sugar transport was not modified by Cd, but when CaCl2 was replaced isotonically with MgCl2, the inhibition is observed. Verapamil at 10−6
M (blocking mainly Ca2+ transport) did not modify the inhibitory effect of cadmium on D-galactose transport. When 10−6
M of A 23187 (Ca2+ specific ionophore) was added in media with/without Ca2+; CdCl2 produced no change in D-galactose transport. These results suggest that Ca and Cd could have affinity for the same chemical
groups of enterocyte membrane, which would be related with the intestinal absorption of D-galactose. 相似文献