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51.
Previous work showed that in hamster red cells the amiloride-sensitive (AS) Na+ influx of 0.8 mmol/liter cells/hr is not mediated by Na-H exchange as in other red cells, but depends upon intracellular Mg2+ and can be increased by 40-fold by loading cells with Mg2+ to 10 mm. The purpose of this study was to verify the connection of AS Na+ influx with Na-dependent, amiloride-sensitive Mg2+ efflux and to utilize AS Na+ influx to explore that pathway.Determination of unidirectional influx of Na+ and net loss of Mg2+ in parallel sets of cells showed that activation by extracellular [Na+] follows a simple Michaelis-Menten relationship for both processes with a K
m
of 105–107 mm and that activation of both processes is sigmoidally dependent upon cytoplasmic [Mg2+] with a [Mg2+]0.5 of 2.1–2.3 mm and a Hill coefficient of 1.8. Comparison of Vmax for both sets of experiments indicated a stoichiometry of 2 Na: l Mg. Amiloride inhibits Na+ influx and Mg2+ extrusion in parallel (K
i
= 0.3 mm). Like Mg2+ extrusion, amiloride-sensitive Na+ influx shows an absolute requirement for cytoplasmic ATP and is increased by cell swelling. Hence, amiloride-sensitive Na+ influx in hamster red cells appears to be through the Na-Mg exchange pathway.There was no amiloride-sensitive Na+ efflux in hamster red cells loaded with Na+ and incubated with high [Mg2+] in the medium with or without external Na+, nor with ATP depletion. Hence, this is not a simple Na-Mg exchange carrier. 相似文献
52.
J. R. Gold T. L. King † L. R. Richardson D. A. Bohlmeyer G. C. Matlock † 《Journal of fish biology》1994,44(4):567-590
Nine polymorphic nuclear-gene (allozyme) loci were surveyed among 491 red drum ( Sciaenops ocellatus ) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a data set of 762 individuals representing 11 sample localities in the Gulf and 175 individuals representing five sample localities in the Atlantic. The combined data set included individuals from the 1986 and 1987 year classes and permitted rigorous testing of both temporal and spatial genetic heterogeneity. Average heterozygosity-per-locus values (estimated using 33 assumed monomorphic loci) were 0·048 (Gulf red drum) and 0·046 (Atlantic red drum). Tests of heterogeneity in allele frequencies between year classes at individual localities and across regions (Gulf and Atlantic) were non-significant. Tests of spatial (geographic) heterogeneity indicated that red drum are weakly subdivided: genetically-differentiated subpopulations occur in the northern Gulf and along the south-eastern Atlantic coast. Genetic data were consistent with the hypothesis that red drum within the Gulf and along the Atlantic coast comprise singie subpopulalions. Genetic differences between Gulf and Atlantic red drum seem likeiy to stem from historical or recent interactions between dispersal and impediments to gene flow. 相似文献
53.
54.
The uptake of lead by two contrasting plant species, radish and red fescue, grown in soils contaminated by mine spoil was investigated. Uptake was found to be poorly correlated either with pH or total Pb concentration in the soils. By contrast, a good correlation was obtained, particularly for red fescue, between Pb uptake and Pb concentration in the solution of equilibrated soil suspensions over a wide range of soil pH, total soil Pb and soil solution Pb concentration.Calculations suggested a similar order of magnitude in the total amounts of Pb taken up by the plants and Pb in the soil solution of the root zone, justifying the latter as a good index of Pb-availability. ei]Section editor: A C Borstlap 相似文献
55.
Complete acid hydrolysis of red algal galactans in the presence of borane - 4-methylmorpholine complex has been shown to prevent the acid degradation of 3,6-anhydrogalactose derivatives by their reduction to the corresponding 3,6-anhydro-galactitols, whereas all the other monosaccharides are liberated essentially in the non-reduced form; the reductive hydrolysis products may be determined quantitatively using gas-liquid chromatography (GLC). The method is recommended for preliminary characterization of the polysaccharide composition of red algal biomass. Partial acid hydrolysis of galactans in the presence of the same reducing agent gives rise to reduced oligosaccharides having terminal 3,6-anhydrogalactitol residues. Based on this reaction, the attribution of unknown galactans to the agar or carrageenan groups is possible by partial reductive hydrolysis of small samples of algal biomass with subsequent identification of agarobiitol or carrabiitol acetates by GLC. Sulfate groups are substantially retained under partial reductive hydrolysis conditions; the isolation by liquid chromatography and elucidation of structures of reduced sulfated oligosaccharides may be of great value for the structural analysis of complex red algal galactans. 相似文献
56.
Involvement of Calcium Channels in Depolarization-Evoked Release of Adenosine from Spinal Cord Synaptosomes 总被引:3,自引:1,他引:2
Abstract: The potential involvement of L- and N-type voltage-sensitive calcium (Ca2+ ) channels and a voltage-independent receptor-operated Ca2+ channel in the release of adenosine from dorsal spinal cord synaptosomes induced by depolarization with K+ and capsaicin was examined. Bay K 8644 (10 n M ) augmented release of adenosine in the presence of a partial depolarization with K+ (addition of 6 m M ) but not capsaicin (1 and 10 μ M ). This augmentation was dose dependent from 1 to 10 n M and was followed by inhibition of release from 30 to 100 n M . Nifedipine and nitrendipine inhibited the augmenting effect of Bay K 8644 in a dose-dependent manner, but neither antagonist had any effect on release of adenosine produced by K+ (24 m M ) or capsaicin (1 and 10 μ M ) ω-Conotoxin inhibited K+ -evoked release of adenosine in a dose-dependent manner but had no effect on capsaicin-evoked release. Ruthenium red blocked capsaicin-induced release of adenosine but had no effect on K+ -evoked release. Although L-type voltage-sensitive Ca2+ channels can modulate release of adenosine when synaptosomes are partially depolarized with K+ , N-type voltage-sensitive Ca2+ channels are primarily involved in K+ -evoked release of adenosine. Capsaicin-evoked release of adenosine does not involve either L- or N-type Ca2+ channels, but is dependent on a mechanism that is sensitive to ruthenium red. 相似文献
57.
Twelve of 24 monospecific caprine reagents produced by absorption of alloimmune antisera identified a complex blood group
system of goats which was designated B, based on the results of a small comparison test with ovine reagents. The frequencies
of the 12 B factors differed significantly among the Australian Angora, Texan Angora, Cashmere, and Dairy goat breeds. Three
of the antigens detected by the reagents were shown to be related as linear subtypes, designated Ba1, Ba2, and Ba3, and inherited as alleles. The segregations of B factors in 80 sire groups involving 1086 offspring demonstrated that groups
of B factors (phenogroups) segregated as products of allelic genes.
This work was supported by a grant from the Australian Stud Book, Alison Road, Randwick, New South Wales 2031, Australia. 相似文献
58.
Shoot tip culture was used to eliminate white clover mosaic virus (WCMV) and red clover necrotic mosaic virus (RCNMV) from red clover, and clover phyllody disease (CP) and clover red leaf disease (CRL) from white clover. Shoot tips up to 2.4 mm (in some cases 3 mm) could regenerate plants free from the pathogens, but the efficiency of elimination, at least for WCMV and CRL, tended to decrease with increasing shoot tip size. The efficiency of plant regeneration from shoot tips generally improved with increasing tip size. 相似文献
59.
Summary DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of minisatellite-like sequences
in the red clover genome. The fingerprints generated by probe 33.6 gave less background and fewer but better defined bands
than those obtained with probe 33.15. Assay of a regenerative somaclonal variant (F49R) by DNA fingerprinting with probe 33.6
detected mutation that was unlinked to the regenerative trait. The fingerprints obtained under the applied conditions also
demonstrated genetic stability of consecutive generations of the regenerants in tissue culture. DNA fingerprints of F1 plants revealed that each polymorphic band was inherited from either one or the other parent. Both probes distinguished individual-specific
genotypes in seven cultivars of red clover. Greater variability in DNA fingerprints was detected between (V=0.899) than within
(0.417≤V≤0.548) cultivars. 相似文献
60.
Hui Wang Lingling Wang Meihua Wu Minghao Fang Zhaohui Huang Xin Min 《Luminescence》2023,38(2):208-215
This paper reports a sequence of a Ca3YAl3B4O15:xEu3+ red phosphor prepared using a high-temperature solid-state reaction. At the excitation of 396 nm, the samples emitted intense red emission centred at ~623 nm, which could be attributed to the 5D0→7F2 transition of the Eu3+ ion. The results showed that the optimum Eu3+ doping concentration of Ca3YAl3B4O15:Eu3+ phosphor was x = 80 mol%, and the concentration quenching mechanism of Ca3YAl3B4O15:Eu3+ red phosphor belonged to the exchange coupling between Eu3+ ions. The Commission Internationale de l'éclairage (CIE) coordinates and colour purity of Ca3Y0.2Al3B4O15:0.8Eu3+ were calculated as (0.6375, 0.3476) and 95.5%, respectively. Moreover, the red emission of the obtained phosphor Ca3YAl3B4O15:0.8Eu3+ exhibited a low thermal quenching behaviour with an intensity retention rate of 92.85% at 150°C. The above results manifest that the Eu3+-activated Ca3YAl3B4O15 phosphor is predicted to be a promising red luminescent component for white light-emitting diodes. 相似文献