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1.
All Lipid-soluble Anaesthetics protect Red Cells   总被引:6,自引:0,他引:6  
FOR the study of molecular events involved in the membrane action of anaesthetics, a cell is required which responds to all anaesthetics and which has a membrane that can be readily isolated. Erythrocytes may serve this purpose both qualitatively and quantitatively, for all lipid-soluble anaesthetics examined so far protect these cells from hypotonic haemolysis. Table 1 lists the anti-haemolytic concentrations of twelve different families of lipid-soluble anaesthetics including steroids1, alcohols2,3, tranquillizers4, fatty acids5, detergents6,7, propranolol8, vasodilators9 and barbiturates10. Drugs which are highly water-soluble, on the other hand, do not protect erythrocytes from hypotonic haemolysis. Tetrodotoxin is a lipid-insoluble local anaesthetic and does not protect human erythrocytes; this compound, however, does not always anaesthetize excitable membranes18.  相似文献   

2.
The respiration of a Sporobolomyces red yeast is investigated with intact cells. The results show that the respiration is not inhibited at all, but moderately accelerated by cyanide and CO. Although the chemical nature of this fact is not yet clarified, the existence of a heat-labile and cyanide-insensitive oxidative enzyme system in this yeast is presumable.  相似文献   

3.
Microflora of Black and Red Pepper   总被引:12,自引:9,他引:3       下载免费PDF全文
Dilution cultures of 30 samples of ground black pepper yielded an average of 39,000 colonies of fungi per g, with a range of 1,700 to 310,000 per g. Total numbers of colonies of bacteria from 11 samples averaged 194,000,000 per g, with a range from 8,300,000 to 704,000,000 per g. A variety of fungi grew from nearly all surface-disinfected whole peppercorns that were cultured. Thirteen samples of ground red pepper from the United States yielded an average of 1,600 colonies of storage fungi per g and an equal number of other fungi; five samples from India yielded an average of 78,900 colonies of storage fungi per g and 169,400 colonies of other fungi per g. Among the fungi from both black and red pepper were Aspergillus flavus and A. ochraceus, some isolates of which, when grown for 8 to 10 days on moist autoclaved corn and fed to white rats or to 2-day-old Pekin ducklings, were rapidly lethal to them. Aflatoxin B1 was isolated from one of the samples of corn on which A. flavus from black pepper was grown. Among the bacteria isolated from ground black pepper were Escherichia coli, E. freudii, Serratia sp., Klebsiella sp., Bacillus sp., Staphylococcus sp., and Streptococcus sp. No cultures of Shigella or Salmonella were found.  相似文献   

4.
The temperature dependence of permeation across human red cell membranes has been determined for a series of hydrophilic and lipophilic solutes, including urea and two methyl substituted derivatives, all the straight-chain amides from formamide through valeramide and the two isomers, isobutyramide and isovaleramide. The temperature coefficient for permeation by all the hydrophilic solutes is 12 kcal mol-1 or less, whereas that for all the lipophilic solutes is 19 kcal mol-1 or greater. This difference is consonant with the view that hydrophilic molecules cross the membrane by a path different from that taken by the lipophilic ones. The thermodynamic parameters associated with lipophile permeation have been studied in detail. ΔG is negative for adsorption of lipophilic amides onto an oil-water interface, whereas it is positive for transfer of the polar head from the aqueous medium to bulk lipid solvent. Application of absolute reaction rate theory makes it possible to make a clear distinction between diffusion across the water-red cell membrane interface and diffusion within the membrane. Diffusion coefficients and apparent activation enthalpies and entropies have been computed for each process. Transfer of the polar head from the solvent into the interface is characterized by ΔG = 0 kcal mol-1 and ΔS negative, whereas both of these parameters have large positive values for diffusion within the membrane. Diffusion within the membrane is similar to what is expected for diffusion through a highly associated viscous fluid.  相似文献   

5.
Recombination hotspots are small chromosomal regions, where meiotic crossover events happen with high frequency. Recombination is initiated by a double‐strand break (DSB) that requires the intervention of the molecular repair mechanism. The DSB repair mechanism may result in the exchange of homologous chromosomes (crossover) and the conversion of the allelic sequence that breaks into the one that does not break (biased gene conversion). Biased gene conversion results in a transmission advantage for the allele that does not break, thus preventing recombination and rendering recombination hotspots transient. How is it possible that recombination hotspots persist over evolutionary time (maintaining the average chromosomal crossover rate) when they are self‐destructive? This fundamental question is known as the recombination hotspot paradox and has attracted much attention in recent years. Yet, that attention has not translated into a fully satisfactory answer. No existing model adequately explains all aspects of the recombination hotspot paradox. Here, we formulate an intragenomic conflict model resulting in Red Queen dynamics that fully accounts for all empirical observations regarding the molecular mechanisms of recombination hotspots, the nonrandom targeting of the recombination machinery to hotspots and the evolutionary dynamics of hotspot turnover.  相似文献   

6.
Analysis for gibberellin-like substances (GA) and cytokinins in cold and non-cold treated fall-bearing and cold treated June-bearing cultivars of red raspberries (Rubus idaeus L.) was made at the 10 and 20 node stages of growth (at 10 nodes, all plants were vegetative; at 20 nodes, only cold treated plants of fall-bearing cultivars were flower induced). Quantitative changes in GAs, as analyzed by the lettuce hypocotyl bioassay, were observed only in flower induced plants. In fall-bearing cultivars at the 20 node stage of growth, there was a 100% greater activity in cold than non-cold treated plants. Likewise, cold treated plants had a 60% greater activity at the 20 than at the 10 node stage of growth. Major qualitative differences in GAs were observed between the 10 and 20 node stage of growth in cold treated fall-bearing cultivars but not in cold treated plants of June-bearing cultivars. Changes in compounds at Rf 0.3 and 0.5 accounted for 35 to 54% of the total increase in GA activity between flower induced and non-induced stages of growth. Cytokinin activity tested by the tobacco callus bioassay was greater at the 20 than at the 10 node stage of growth in all cultivars and treatments. However, cold treated plants of the fall-bearing type had 70% greater cytokinin activity than non-cold treated plants at both stages of growth. It is suggested that gibberellins, possibly acting synergistically with cytokinins, are involved inflower induction in red raspberries.  相似文献   

7.
N S Agar 《Enzyme》1976,21(3):243-247
The following biochemical features were measured in the red blood cells of high and low glutathione goats: reduced glutathione (GSH) stability; GSH regeneration; glucose consumption; lactate production; levels of adenosine triphosphate and 2,3-diphosphoglycerate, and the activities of nine different enzymes of Embden-Meyerhof and pentose phosphate pathways of glucose metabolism. Apart from significant differences in the GSH stability the results of all the tests were found to be similar in the two groups.  相似文献   

8.
《PloS one》2015,10(8)
Plants provide fundamental support systems for life on Earth and are the basis for all terrestrial ecosystems; a decline in plant diversity will be detrimental to all other groups of organisms including humans. Decline in plant diversity has been hard to quantify, due to the huge numbers of known and yet to be discovered species and the lack of an adequate baseline assessment of extinction risk against which to track changes. The biodiversity of many remote parts of the world remains poorly known, and the rate of new assessments of extinction risk for individual plant species approximates the rate at which new plant species are described. Thus the question ‘How threatened are plants?’ is still very difficult to answer accurately. While completing assessments for each species of plant remains a distant prospect, by assessing a randomly selected sample of species the Sampled Red List Index for Plants gives, for the first time, an accurate view of how threatened plants are across the world. It represents the first key phase of ongoing efforts to monitor the status of the world’s plants. More than 20% of plant species assessed are threatened with extinction, and the habitat with the most threatened species is overwhelmingly tropical rain forest, where the greatest threat to plants is anthropogenic habitat conversion, for arable and livestock agriculture, and harvesting of natural resources. Gymnosperms (e.g. conifers and cycads) are the most threatened group, while a third of plant species included in this study have yet to receive an assessment or are so poorly known that we cannot yet ascertain whether they are threatened or not. This study provides a baseline assessment from which trends in the status of plant biodiversity can be measured and periodically reassessed.  相似文献   

9.
Red light-enhanced pelletability of phytochrome was observed in extracts of all 11 plants tested: Avena sativa L., Secale cereale L., Zea mays L., Cucurbita pepo L., Sinapis alba L., Pisum sativum L., Helianthus anuus L., Raphanus sativus L., Glycine max (L.) Merr., Phaseolus vulgaris L., and Lupinus albus L. This enhanced pelletability was observed in all 11 plants following in situ irradiation (in vivo binding) but only in Sinapis and Cucurbita after irradiation of crude extracts (in vitro binding). In vivo binding was not strongly dependent upon pH and, with few exceptions, was not markedly sensitive to high salt concentration, whereas in vitro binding was completely reversed by both high pH and high salt concentration. However, both binding phenomena were observed only with a divalent cation in the extract buffer. In vivo binding was further characterized using Avena which showed an increase in pelletability from less than 10% in dark control extracts to more than 60% in extracts of red light-irradiated shoots. The half-life for binding was 40 seconds at 0.5 C and was strongly temperature-dependent, binding being complete within 5 to 10 sec at 22 C. If pelletable phytochrome in the far red-absorbing form was photoconverted back to the red-absorbing form in situ, phytochrome was released from the pelletable condition with a half-life of 25 minutes at 25 C and 100 minutes at both 13 C and 3 C. No cooperativity in red light-enhanced pelletability with respect to phytochrome-far red-absorbing form was observed.  相似文献   

10.
Multi-species synchronous spawning was first described on reefs off the east and west coast of Australia. In contrast, locally abundant species in the northern Red Sea and the central Pacific have little overlap in the time of reproduction. Consequently, the idea developed that high levels of spawning synchrony both within and among species was largely confined to Australian reefs. Here, we show that gamete maturity in colonies of the genus Acropora was highly synchronous in the Red Sea. In early April 2008, at two locations separated by 300 km, 13 of 24 species sampled had mature colonies, and a further 9 species had immature colonies. In late April–early May 2008, all colonies sampled had no oocytes, indicating colonies had spawned a few days after the full moon of 20 April 2008. Similarly, in 2009, 99% of colonies from 17 species at Hurghada were mature in late April, and all were empty in early May. Spawn slicks suggested many of these colonies had released gametes three night prior to the full moon on 8 May 2009. This level of synchrony in gamete maturity is among the highest ever recorded and similar to that typically recorded in Acropora assemblages on Australian reefs. While further work is required to document the night of gamete release, these data strongly suggest that high levels of spawning synchrony are a regular feature of these Red Sea coral assemblages and that multi-species spawning occurs on or around the full moon in April and/or May.  相似文献   

11.
Summary A detailed quantitative analysis of the anisotropic properties of Sirius Red F3B, Picrosirius, and Chlorantine Fast Red crystals, and of their complexes with a macromolecularly oriented protein either in a pure form or as part of a tissue structure was carried out. Collagen I was used as the protein model. Linear dichroism and dispersion of birefringence were investigated in dye aggregates, in stained filaments of collagen I and in collagen bundles in sections of tendon. A positive linear dichroism, the characteristics of which varied as a function of the dye type used, was demonstrated for the dye aggregates and stained substrates. However, even thin regions of the stained tendon collagen bundles showed very high absorbances, differing from the pattern reported previously, for collagen stained with another sulphonated azo dye, Xylidine Ponceau. Consequently, not all these dyes enable protein concentration and orientation to be determined in collagen-containing structures. From the linear dichroism patterns it is assumed that the long axis of the molecules of these azo dye is mostly parallel to that of filaments of pure collagen I and statistically parallel to the long axis of collagen bundles of tendon sections. The dye aggregates and, stained pure collagen I and tendon collagen bundles exhibited birefringent images with interference colours that varied as a function of thickness and packing state of the preparations, which is in agreement with reports in the literature. The optical retardations of the collagen bundles increased by a factor of 5–6 times after staining with Picrosirius. From data on form dichroism it is concluded that when studying the macromolecular orientation of collagen preparations stained with azo dyes, the choice of the mounting medium deserves consideration.  相似文献   

12.
Coevolution of two species is typically thought to favour the evolution of faster evolutionary rates helping a species keep ahead in the Red Queen race, where ‘it takes all the running you can do to stay where you are’. In contrast, if species are in a mutualistic relationship, it was proposed that the Red King effect may act, where it can be beneficial to evolve slower than the mutualistic species. The Red King hypothesis proposes that the species which evolves slower can gain a larger share of the benefits. However, the interactions between the two species may involve multiple individuals. To analyse such a situation, we resort to evolutionary multiplayer games. Even in situations where evolving slower is beneficial in a two-player setting, faster evolution may be favoured in a multiplayer setting. The underlying features of multiplayer games can be crucial for the distribution of benefits. They also suggest a link between the evolution of the rate of evolution and group size.  相似文献   

13.
Red Blood Cell Damage by Shear Stress   总被引:16,自引:4,他引:12       下载免费PDF全文
A series of careful studies has been made on blood damage in a rotational viscometer. Specific attention has been focused on the effects of solid surface interaction, centrifugal force, air interface interaction, mixing of sheared and unsheared layers, cell-cell interaction, and viscous heating. The results show that there is a threshold shear stress, 1500 dynes/cm2, above which extensive cell damage is directly due to shear stress, and the various secondary effects listed above are negligible. By analysis of these results and those of prior workers it is shown that the exposure time-shear stress plane is divided into two distinct regimes. In the regime of relatively low stresses and exposure times there is relatively little damage, and the damage is dominated by solid surface interaction effects. In the other regime, at high stresses and exposure times, stress effects alone dominate and very high rates of hemolysis occur. The experimental findings of all prior workers are shown to be consistent when interpreted in this way.  相似文献   

14.
On food preference in the Red fox   总被引:2,自引:0,他引:2  
  • 1 Foxes treat different prey species in a variety of ways, eating, burying, or discarding them on the basis of preference.
  • 2 Because foxes often utilize cached food and because they can remember which prey species is in a given cache the preference effect can be longstanding.
  • 3 Evidence from the literature suggests that comparable effects of preference for different species of small mammals affects the diet of wild foxes and their behaviour in the same way as demonstrated in these experiments.
  • 4 Certain distastes appear common to all foxes and most carnivores, for instance, insectivore and carnivore meat, in particular that of their own species.
  • 5 An incidence of active cannibalism by a fox is reported.
  • 6 The effect of food preference is shown to change during the course of one individual's life perhaps as a consequence of such factors as rearing cubs and competition for food.
  • 7 One effect of the behavioural consequences of food preference is to defer the decision of what to eat.
  • 8 That the fox will kill animals that it does not eat means that populations of animals that are not strictly fox prey are still at risk from fox predatory activity.
  相似文献   

15.
Phytochrome is rapidly degraded in vivo after photoconversion from the stable red-absorbing (Pr) form to the far red-absorbing (Pfr) form. Previously, we have shown in etiolated oat seedlings that ubiquitin-phytochrome conjugates (Ub-P) appear after Pfr formation suggesting that oat phytochrome is rapidly degraded by a ubiquitin-dependent proteolytic pathway. Here, we extend this observation to etiolated tissue from other monocotyledonous (corn [Zea mays. (L.)] and rye [Secale cereale (L.)] and dicotyledonous species (pea [Pisum sativum (L,)] and zucchini squash [Cucurbita pepo (L.)]). Following Pfr formation by red light, all four species synthesized a heterogeneous series of Ub-P that appeared and disappeared concomitant with the degradation of the chromoprotein. When Pfr was photoconverted back to Pr by a far-red light pulse, degradation of phytochrome ceased and the levels of Ub-P concomitantly dropped. In pea and zucchini squash, loss of Ub-P after photoconversion of Pfr back to Pr was rapid, occurring with a half-life of approximately 5 to 10 minutes. These data indicate that the accumulation of Ub-P after Pfr formation is a general phenomenon in etiolated seedlings of higher plants and further support the hypothesis that plants degrade Pfr via Ub-P intermediates.  相似文献   

16.
There is a disagreement about the value of red cell sorbitol as an indicator of diabetic control. We studied 7 insulin requiring diabetics, one for 10 days and 6 for 24 hours. In the 10-day study, blood samples were obtained every 4-6 hours. Sequential analysis of plasma glucose and red cell sorbitol levels showed that simultaneous levels had the best correlation r = 0.534, P less than .001. In the 24-hour studies, blood samples were obtained at 1 to 4-hour intervals. Three of the 6 patients showed the best correlation between simultaneous plasma glucose and red cell sorbitol, with r = 0.727 to 0.957 and P less than .001 to P less than .07. When plasma glucose values were compared to red cell sorbitol levels 1, 2, 4, 8 and 12 h later, correlation coefficients were not as good as the simultaneous comparison. We conclude that the measurement of red cell sorbitol correlates well with simultaneous plasma glucose in some but not all diabetic subjects and provides no additional information to the clinician.  相似文献   

17.
Summary The Red Queen principle states that a set of interacting species reaches an evolutionary equilibrium at which all their rates of coevolution exactly balance each other. The lag-load model, which is one way of searching for Red Queens, has, by itself, previously predicted that they do not exist. But this model has assumed that infinite maladaptedness is possible. The lag-load model is improved by assuming that once the lag load of all but one species is determined, so is that of the final species. This assumption eliminates the possibility of infinite maladaptedness. Its result is to allow the lag-load model to yield Red Queen coevolution. It does this whether or not speciation and extinction rates are included. Thus the lag-load model is harmonized with the earlier Red Queen model derived from studies of predation.Because of the intercorrelation of phenotypic traits, the predatory model concluded that the eventual stable rate of coevolution must be zero (except for intermittent bursts after some correlation or compromise is successfully broken). Another model that predicts stable coevolutionary rates of zero is that of evolutionarily stable strategies (ESS).Red Queen assumes that the more extreme a phenotypic trait is, the better it is, and that there are no constraints on the growth of such a phenotypic trait value. Such traits are the key to the Red Queen prediction of progressive coevolution. ESS models make no such assumptions. Eliminating unbounded traits from the model of predator-victim evolution changed its prediction from progressive coevolution to stasis. Before this paper, no model had dealt simultaneously with both unbounded and constrained traits.To handle both sorts of phenotypic traits at the same time in the same model, we abandoned lag load as a measure of evolutionary rate (lag loads do not uniquely determine phenotype). Instead, we used the traditional assumption that rate is proportional to the slope of the adaptive landscape. A model, relying on continuous evolutionary game theory, was developed and simulated under various conditions in two or three species sets, with up to five independent traits coevolving simultaneously. The results were: (1) there was always a set of equilibrium densities eventually achieved by coevolution; if the population interaction represented by this stable coevolutionary state is also stable, then the system should persist whether it evolves further or not; (2) whenever traits were present which were unbounded and best at their most extreme values, then a Red Queen emerged; (3) whenever traits were present which were correlated with each other or constrained below infinity, then an ESS emerged; (4) if both types were present, both results occurred: Red Queen in the unbounded traits and ESS in the constrained ones.Because unbounded traits may not exist, the Red Queen may have no domain. But the domain of ESS is real. ESS should lead to the evolutionary pattern called punctuated equilibrium. The changes in design rules which punctuate stasis should lead to an ever-expanding independence of traits from each other, i.e. to more and more refined differentiation. A single set of design rules which governs a set of species is called a fitness-generating function. Such functions may help to define the concepts of adaptive zone and ecological guild.  相似文献   

18.
The purified red yeast cell wall lytic enzyme of Penicillium lilacinum No. 2093 has a potent saccharifying activity against cell walls, but the living cell lytic activity of it is considerably lower than that of the culture filtrate. Therefore, the living cell lytic factors in the culture filtrate were examined. The alkaline protease of Pen. lilacinum played an important role for living cell lysis. The synergistic effect on living cell lysis was also detected, when acid proteases from various origins were combined with the cell wall lytic enzyme. These results indicated that the protein layers of red yeast cell surface inhibited the action of a glycanase,cell wall lytic enzyme, and the protein molecule contributed to retain the rigid structure of the wall.  相似文献   

19.
The mode of adaptation of the photosynthetic apparatus of three unicellular green algae, Ankistrodesmus braunii, Chlorella fusca and Chlorella saccharophila to red and blue light are documented by the fluence-rate curves of photosynthetic oxygen evolution. For all three algae tested photosynthetic capacity, respiration and light compensation point were higher for cells grown under red light, while the chlorophyll content increased in blue light-grown cells. Blue light-adapted cells have a lower chlorophyll a to chlorophyll b ratio and more chlorophyll in the light-harvesting system than red light-adapted cells, as shown in the electrophoretic profile of the pigment-protein complexes. It is concluded that the action of red light resembles that of high levels of white light, while blue light causes the same effects as low levels of white light. In agreement with previous publications these findings indicate that the mode of adaptation to different light qualities is ubiquitous in unicellular green algae.  相似文献   

20.
In late 1984 10 young Red Squirrels ( Sciurus vulgaris ) trapped in Scotland were released into Regent's Park and monitored by radio-telemetry. We wanted to investigate the reasons why the introduced Grey Squirrel has replaced the Red over much of Britain; disease, aggression and ecological competition have all been suggested as the cause. The relevant guidelines governing policy on reintroductions were followed. A few months after release, the animals appear well established. They benefit from a specially-designed hopper which allows them to feed from it but prevents Grey Squirrels doing so.  相似文献   

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