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991.
J.-Y. Maillard T.S. Beggs M.J. Day R.A. Hudson A.D. Russell 《Journal of applied microbiology》1996,80(6):605-610
The coliphage K1-5 has been used in an automated assay to monitor the viricidal activity of various disinfectants. This indirect assay based on the spectrophotometric reading of the lysis of the host cell ( Escherichia coli D837) produced encouraging results and was faster than the overlay counting method (previously studied) which relies on plaque formation. However, differences in sensitivity towards some disinfectants were observed between the two methods. 相似文献
992.
Summary A new application of a recently developed electronic radiation-damping (RD) control system is presented. It is possible to amplify radiation damping so as to make the water magnetization return back to its equilibrium direction in a time shorter than the characteristic RD time. Certain types of experiments involving radiation damping as a selective inversion pulse can be significantly improved by this new method. Moreover, amplification of RD is shown to improve water suppression and consequently the dynamics of 2D NOESY experiments on proteins. 相似文献
993.
The evolution of dispersal in a two-patch system: some consequences of differences between migrants and residents 总被引:5,自引:0,他引:5
Jean-Yves Lemel Sophie Belichon Jean Clobert Michael E. Hochberg 《Evolutionary ecology》1997,11(5):613-629
We investigate how age-structure and differences in certain demographic traits between residents and immigrants of a single species act to determine the evolutionarily stable dispersal strategy in a two-patch environment that is heterogeneous in space but constant in time. These two factors have been neglected in previous models of the evolution of dispersal, which generally consider organisms with very simple life-cycles and assume that, whatever their origin, individuals in a given habitat have the same bio-demographic characteristics. However, there is increasing empirical evidence that dispersing individuals have different demographic properties from phylopatric ones. We develop a matrix model in which recruitment depends on local population densities. We assume that dispersal entails a proportional cost to immigrant fecundity, which can be compensated by differences in survival rates between immigrants and residents. The evolutionarily stable strategies (ESS) for dispersal are identified using a combination of analytical expressions and numerical simulations. Our results show that philopatry is selected (1) when dispersal rates do not vary in space, (2) when the metapopulation is a source-sink system and (3) when dispersal rates vary in space (asymmetric dispersal) and immigrants do not compensate for their reduced fecundity. We observe that non-zero asymmetric dispersal rates may be evolutionarily stable when (1) immigrants and residents are demographically alike and (2) immigrants compensate totally for their reduced fecundity through an increase in adult survival. Under these conditions, we find that the ESS occurs when the fitnesses at equilibrium in the two habitats, measured in our model by the realized reproductive rates, are each equal to unity. A comparison with previous studies suggests a unifying rule for the evolution of dispersal: the dispersal rates which permit the spatial homogenization of fitnesses are ESSs. This condition provides new insight into the evolutionary stability of source-sink systems. It also supports the hypothesis that immigrants have adapted demographic strategies, rather than the hypothesis that dispersal is costly and immigrants are at a disavantage compared with residents. 相似文献
994.
995.
A continuous restriction map from HLA-E to HLA-F. Structural comparison between different HLA-A haplotypes 总被引:2,自引:0,他引:2
Abdel El Kahloun Corine Vernet Anne-Marie Jouanolle Joëlle Boretto Valérie Mauvieux Jean-Yves Le Gall Véronique David Pierre Pontarotti 《Immunogenetics》1992,35(3):183-189
The class I region of the human major histocompatibility complex contains genes encoding the classical transplantation antigens (HLA-A, B, and C), at least three new class I genes (HLA-E, F, and G) and many class I pseudogenes (including HLA-H). By pulse field gel electrophoresis and using five rare cutter enzymes, we have constructed a precise and continuous map of 1200 kilobases (kb) around HLA-A. The blots were hybridized with HLA-A, E, and F-specific probes and with new probes derived from yeast artificial chromosomes and cosmids of the class I region. We have compared the genomic organization of the same 1200 kb in three homozygous lymphoblastoid cell lines corresponding to three different HLA haplotypes (A3, A24, and A31). The differences in size observed may have been caused by insertions and deletions and may prove valuable in understanding the evolution of the HLA chromosomal region. 相似文献
996.
Raynald Laprade Jean-Yves Lapointe Sylvie Breton Marcelle Duplain Jean Cardinal 《The Journal of membrane biology》1991,121(3):249-259
Summary Intracellular potassium activity (a
K
i
) was measured in control conditions in mid-cortical rabbit proximal convoluted tubule using two methods: (i) by determination of the K+ equilibrium potential (E
K) using Ba2+-induced variations in the basolateral membrane potential (V
BL) during transepithelial current injections and (ii) with double-barrel K-selective microelectrodes. Using the first method, the meanV
BL was –48.5±3.2 mV (n=16) and the meanE
K was –78.4±4.1 mV corresponding to aa
K
i
of 68.7mm. With K-selective microelectrodes,V
BL was –36.6±1.1 mV (n=19),E
K was –64.0±1.1 mV anda
K
i
averaged 40.6±1.7mm. While these lastE
K andV
BL values are significantly lower than the corresponding values obtained with the first method (P<0.001 andP<0.01, respectively), the electrochemical driving force for K transport across the basolateral membrane (
K =V
BL –E
K) is not significantly different for both techniques (30.1±3.3 mV for the first technique and 27.6±1.8 mV for ion-selective electrodes). This suggests an adequate functioning of the selective barrel but an underestimation ofV
BL by the reference barrel of the double-barrel microelectrode. Such double-barrel microelectrodes were used to measure temporal changes ina
K
i
and
K in different experimental conditions where Na reabsorption rate (J
Na) was reduced.a
K
i
was shown to increase by 12.2±2.7 (n=5) and 14.1±4.4mm (n=5), respectively, whenJ
Na was reduced by omitting in the luminal perfusate: (i) 5.5mm glucose and 6mm alanine and (ii) glucose, alanine, other Na-cotransported solutes and 110mm Na. In terms of the electrochemical driving force for K exit across the basolateral membrane,
K, a decrease of 5.4±2.0 mV (P<0.05,n=5) was measured when glucose and alanine were omitted in the luminal perfusate while
K remained unchanged whenJ
Na was more severely reduced (mean change =–1.7±2.1 mV, NS,n=5). In the latter case, this means that the electrochemical driving force for K efflux across the basolateral membrane has not changed while both the active influx through the Na–K pump and the passive efflux in steady state are certainly reduced. If the main pathway for K transport is through the basolateral K conductance, this implies that this conductance must have decreased in the same proportion as that of the reduction in the Na–K pump activity. 相似文献
997.
Thrombin, plasmin and tissue plasminogen activator (one- and two-chain forms) were examined with respect to their reaction with the suicide substrate, 3,4-dihydro-3-benzyl-6-chloromethylcoumarin, at 4 degrees C. The enzymes were irreversibly inhibited and the apparent second-order rate constants ki/Ki were 31,000, 316, 187 and 250 M-1.s-1, respectively. The extent of fibrin clot lysis induced by urokinase and two-chain tissue plasminogen activator was considerably decreased after treatment of these enzymes with the dihydrocoumarin derivative (molar excess of inhibitor over enzyme ranging from 6 to 21 for urokinase and 50 to 1500 for tissue plasminogen activator). This inhibitor has been tested as anticoagulant in human plasma and was effective at prolonging the prothrombin time from 12 to 40 s. 相似文献
998.
999.
Joëlle Boretto Anne-Marie Jouanolle Jacqueline Yaouanq Abdel El Kahloun Valérie Mauvieux Martine Blayau Muriel Perichon André Le Treut John Clayton Nicolas Borot Jean-Yves Le Gall Pierre Pontarotti Véronique David 《Human genetics》1992,89(1):33-36
Summary Two yeast artificial chromosomes of the HLA class I region were subcloned. Four of the subclones studied displayed restriction polymorphisms that corresponded to six bi-allelic series. Allelic distribution of the anonymous markers was then studied by comparing a control population with a group of patients with familial haemochromatosis. Only one marker presents an unequivocal association with the haemochromatosis gene and is 100kb centromeric to HLA-A. This association however is not as strong as with HLA-A3. The results suggest two possible locations for the haemochromatosis gene: less than 100kb centromeric to the HLA-A locus, or on the telomeric side. 相似文献
1000.
Philippe Potin Pascale Patier Jean-Yves Floc'h Jean-Claude Yvin Cyrille Rochas Bernard Kloareg 《Journal of applied phycology》1992,4(2):119-128
Tank cultivation ofDelesseria sanguinea was investigated in order to manipulate conditions for vegetative growth and to provide biomass for the analysis of cell
wall polysaccharides. Seasonality is subject to short-day photoperiodic control. Night-break or long-day conditions prevented
fertility in tetrasporophytes and gametophytes and triggered outgrowth of new blades. Long-day illuminations allowed a 1%
daily growth rate. Seawater temperature below 13 °C was necessary for inducing formation of new blades. Both wild and cultivated
ofD. sanguinea plants contained a non gelling sulfated heteropolysaccharide composed of a galactosyl backbone branched with xylosyl residues.
The hot water extract at neutral pH displayed the highest anticoagulant activity (5 μg ml-1 polysaccharide concentration in APTT clotting assay). No obvious differences were found in polysaccharide chemical composition
and properties between gametophytes and sporophytes or between cultivated and wild plants. 相似文献