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21.
G. N. Reiner L. Delgado-Marín N. Olguín S. Sánchez-Redondo M. Sánchez-Borzone E. Rodríguez-Farré C. Suñol D. A. García 《Cell biochemistry and biophysics》2013,67(2):515-525
Phenol compounds, such as propofol and thymol, have been shown to act on the GABAA receptor through interaction with specific sites of this receptor. In addition, considering the high lipophilicity of phenols, it is possible that their pharmacological activity may also be the result of the interaction of phenol molecules with the surrounding lipid molecules, modulating the supramolecular organization of the receptor environment. Thus, in the present study, we study the pharmacological activity of some propofol- and thymol-related phenols on the native GABAA receptor using primary cultures of cortical neurons and investigate the effects of these compounds on the micro viscosity of artificial membranes by means of fluorescence anisotropy. The phenol compounds analyzed in this article are carvacrol, chlorothymol, and eugenol. All compounds were able to enhance the binding of [3H]flunitrazepam with EC50 values in the micromolar range and to increase the GABA-evoked Cl? influx in a concentration-dependent manner, both effects being inhibited by the competitive GABAA antagonist bicuculline. These results strongly suggest that the phenols studied are positive allosteric modulators of this receptor. Chlorothymol showed a bell-type effect, reducing its positive effect at concentrations >100 μM. The concentrations necessary to induce positive allosteric modulation of GABAA receptor were not cytotoxic. Although all compounds were able to decrease the micro viscosity of artificial membranes, chlorothymol displayed a larger effect which could explain its effects on [3H]flunitrazepam binding and on cell viability at high concentrations. Finally, it is suggested that these compounds may exert depressant activity on the central nervous system and potentiate the effects of general anesthetics. 相似文献
22.
Summary Lactic acid produced by continuous culture of L.casei in an upflow packed bed reactor, was recovered with Amberlite IRA 400 in a fluidized bed column. Bed expansions of 1.25 and 2.25 were applied. Reutilization did not alter the capability of net recovery of 0.048 ± 0.01 g lactic acid/g resin. When 2200 cm/h of ascensional velocity was used, (bed expansion of 2.25), the resin adsorbed 39.3% of the initial lactic acid and 63.5% was eluted. This resin supported the highest exchange capacity of 0.126 g lactic acid/g resin. Applying high flow rates, the process has potential industrial applications due to the short time employed. 相似文献
23.
Martha L. Bohórquez Alonso Jorge Martínez Cotrina David Aguilar Pardo Enrique Font Miguel Molina-Borja 《Journal of Ethology》2010,28(2):305-311
Many vertebrate species show display behaviors when predators are in their vicinity. Some of these displays may inform the
predator of the improbability of capturing the prey (i.e., pursuit-deterrent displays) and are potentially advantageous to
both predator and prey. Here we present data on a tail display performed by Gonatodes albogularis, a diurnal tropical gecko. We performed transect surveys in three habitats near Bogotá in Colombia. Geckos detected during
transects were approached by the observer in a standardized way, and details of their tail-waving displays were recorded.
In control recordings animals were watched from a distant site without approaching them. Results showed sexual differences
in tail-waving display: when approached by the observer, males performed this behavior more frequently than females. We found
no significant differences between males and females in flight-initiation distances and height above the substratum when they
were initially located. Results also showed that males displayed more frequently when approached than when the simulated predator
remained stationary. We interpret these results as evidence that the display functions as a pursuit-deterrent signal to potential
predators. However, as some tail displays were performed in the presence of conspecifics, the display may also have a social
function. 相似文献
24.
Of all the genera of woody bamboos described from America, only three have pseudospikelets—Atractantha, Elytrostachys, and Guadua. The former two have pseudospikelets with an elongated rachilla internode that precedes the floret, making it pedicellate; they also share a type of leaf anatomy that separates them from the latter. The two new genera herein described, Criciuma and Eremocaulon, show most similarity to species of Guadua, both in spikelet morphology and in leaf anatomy. The study of these new taxa has helped to clarify the limits of New World genera with pseudospikelets and strengthened the case for maintaining Guadua as a genus distinct from its Old World counterpart, Bambusa. We are now able to discern a New World line of bamboos that includes Criciuma, Eremocaulon, and Guadua, separate from an Old World line that includes Bambusa, Dendrocalamus, and several other genera. 相似文献
25.
The rate and sensitivity to inhibitors (KCN and salicylhydroxamic acid[SHAM]) of respiratory oxygen uptake has been investigated in photosynthetic organs of several freshwater aquatic plant species: six angiosperms, two bryophytes, and an alga. The oxygen uptake rates on a dry weight basis of angiosperm leaves were generally higher than those of the corresponding stems. Leaves also had a higher chlorophyll content than stems. Respiration of leaves and stems of aquatic angiosperms was generally cyanide-resistant, the percentage of resistance being higher than 50% with very few exceptions. The cyanide resistance of respiration of whole shoots of two aquatic bryophytes and an alga was lower and ranged between 25 and 50%. These results suggested that the photosynthetic tissues of aquatic plants have a considerable alternative pathway capacity. The angiosperm leaves generally showed the largest alternative path capacity. In all cases, the respiration rate of the aquatic plants studied was inhibited by SHAM alone by about 13 to 31%. These results were used for calculating the actual activities of the cytochrome and alternative pathways. These activities were generally higher in the leaves of angiosperms. The basal oxygen uptake rate of Myriophyllum spicatum leaves was not stimulated by sucrose, malate or glycine in the absence of the uncoupler carbonylcyanide-m-chlorophenylhydrazone (CCCP), but was greatly increased by CCCP, either in the presence or in the absence of substrates. These results suggest that respiration was limited by the adenylate system, and not by substrate availability. The increase in the respiratory rate by CCCP was due to a large increase in the activities of both the cytochrome and alternative pathways. The respiration rate of M. spicatum leaves in the presence of substrates was little inhibited by SHAM alone, but the SHAM-resistant rate (that is, the cytochrome path) was greatly stimulated by the further addition of CCCP. Similarly, the cyanide-resistant rate of O2 uptake was also increased by the uncoupler. 相似文献
26.
B. Friebe M. C. Cermeño F. J. Zeller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,73(3):337-342
Summary C-banding patterns and nucleolar activity were analyzed in Dasypyrum villosum, its added chromosomes to hexaploid wheat and the hexaploid amphiploid Triticum dicoccum-D. villosum. Two different populations of the allogamous species D. villosum (2n= 14, VV) from Greece and Italy were analyzed showing a similar polymorphism for C-banding pattern. Six of the seven addition lines were identified by their characteristic C-banding pattern. No polymorphism between both members of each added alien chromosome was found. Furthermore, nucleolar activity and competition were studied by using silver staining procedure. In D. villosum only one chromosome pair, A, was found to be responsible for organizing nucleoli. The results obtained in the amphiploid and in the addition lines demonstrate that nucleolar activity is restricted to SAT-chromosomes 1B and 6B of wheat, while those of D. villosum remain inactive. 相似文献
27.
Alvaro García-Tejedor A. Raul Castaño Federico Morán Francisco Montero 《Journal of molecular evolution》1987,26(4):294-300
Summary The most relevant properties of hypercycles were previously studied mainly from a theoretical point of view. We have developed a Monte Carlo method simulating hypercyclic organization to obtain information about the dynamics of this prebiotic organization. Nucleation, growth, and selective properties have been tested and the results obtained are in good agreement with those of the theoretical predictions. The influence of hypercyclic organization of the error threshold has also been studied. As a consequence of the emergence of a hypercycle, the value of this threshold decreases. The amount of this decrease depends on the population size. Moreover, for some interval of quality factor values, either the hypercycle organization or an error catastrophe can be produced, depending on the initial conditions. The influence of these phenomena on both the dynamic behavior and evolutionary advantages of the hypercycle, as well as their decisive roles on genome size, are discussed.Presented at the FEBS Symposium on Genome Organization and Evolution, held in Crete, Greece, September 1–5, 1986 相似文献
28.
Marie Pauline J. Evers Bauke Zelle Daniel S. Peeper Willem H. Mager Rudi J. Planta Aldur W. Eriksson Rune R. Frants 《Human genetics》1987,77(2):182-187
Summary Three human cosmid clones containing pepsinogen A (PGA) encoding sequences were isolated from a genomic bank derived from a single individual. One cosmid contains two PGA genes in tandem in a head-to-tail orientation, while the other two cosmids each contain a single PGA gene. The three cosmids were characterized by restriction mapping and sequence analysis (exons 1 and 2 and flanking regions). As judged from these data, three of the four PGA genes isolated appear to be nearly identical, but one of the tandem genes is clearly different from the other genes. The first exon of all four genes codes for the same amino acid sequence. However, in the second exon of one of the tandem genes we found a nucleotide substitution giving rise to a GluLys substitution of the 43rd amino acid residue of the activation peptide, leading to a charge difference of the corresponding isozymogens. The presence of two distinct PGA genes in the isolated gene pair conclusively proves the multigene structure of the PGA system. These genes might be responsible for at least part of the electrophoretic polymorphism at the protein level. 相似文献
29.
The germination response to NaCl treatments has been studied in Melilotus seed populations collected from saline and non-saline
soils in the Guadalquivir delta.
The rank orders for salt tolerance and seed weight were the same in the threeMelilotus species living in this area:Melilotus messanensis>M. segetalis>M. indica.
Within the species, differences in germination response to salinity were found inM. indica (6 populations) andM. segetalis (8 populations). The relationship between salt tolerance during germination and salinity of maternal habitat is discussed. 相似文献
30.
Leghemoglobin was localized by immunogold techniques in nodules of Lupinus albus cv Multolupa inoculated with Bradyrhizobium sp. (Lupinus) strain ISLU 16. The protein localization was performed in nodules embedded in Spurr's and Araldite epoxy resins and Lowycryl K4M. A very good preservation of both the ultrastructure and antigenicity was obtained with the tissues embedded in Araldite following glutaraldehyde fixation and unpostfixed in osmium tetroxide. Lupin leghemoglobin is a stable and abundant protein which allows a conventional method to be safely used for localization of leghemoglobin. Labeling of leghemoglobin was specifically confined to the cytosol matrix and nuclei. Gold particles were never observed in the peribacteroidal spaces nor in the cytoplasmic organelles of the infected cells. Decrease of leghemoglobin was observed when the plants were grown with 10.7 micromolar and 21.4 micromolar of nitrate. 相似文献