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1.
The conduction system of the mouse heart 总被引:1,自引:0,他引:1
2.
T F Aripov I A Rozenshtein B A Salakhutdinov A A Lev V A Gotlib 《General physiology and biophysics》1987,6(4):343-357
The interaction of cytotoxin Vc1 and Vc5 from Central Asian cobra and melittin from the bee venom with multilayer liposomes prepared from dimiristoylphosphatidylcholine with an addition of phosphatidic acid have been studied by the method of differential scanning calorimetry. Incorporation of Vc1, Vc5 and melittin into the lipid resulted in pronounced changes in the thermodynamic properties of the lipid. Polypeptides studied induced lateral phase separation in the lipid. Interaction between molecules of the toxins and the lipid resulted in the formation of a new lipid phase characterized by a higher melting temperature and lower phase transition enthalpy. 相似文献
3.
In this paper the authors present a comparative study of the actions of the antibiotics primycin and gramicidin on the erythrocyte membrane permeability. It has been found that both antibiotics have a nonlinear effect on the membrane permeability. Above a threshold antibiotic concentration, which is characteristic of the type of the antibiotic, the cation permeability of the erythrocyte membranes increases sharply. In the range of nonlinearity the transport-kinetic curves level off before achieving the equilibrium radioactive ion distribution between the extra- and intracellular spaces. A stochastic model of the cooperative and aspecific incorporation of antibiotic molecules into the membrane explains the experimental findings. The authors conclude that membrane permeability increases at the places where two or more antibiotic molecules form aggregates in the membrane. 相似文献
4.
L V Schagina K Blaskó A E Grinfeldt Y E Korchev A A Lev 《Biochimica et biophysica acta》1989,978(1):145-150
The exchange diffusions of tracer cations (22Na+, 86Rb+) are studied on gramicidin-A-treated red blood cell (RBC) membranes. A time-dependent decrease in cation permeability has been observed and has been considered to be the result of a channel inactivation process. The channel inactivation appears at 20 and 30 degrees C but not at a temperature as low as 6 degrees C. The gramicidin A channel inactivation can be monitored by a conductivity decay of molecular lipid membranes (BLM) prepared either from cholesterol or from a mixture of cholesterol and phospholipids but not of pure phosphatidylethanolamine. The role of cholesterol in the channel inactivation is discussed. 相似文献
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Iodination of cytotoxin P4, isolated from the venom of Naja nigricollis nigricollis, develops gradually and depends on the molar ratio between the free iodine and the cytotoxin reaching a maximum of two equivalents at a molar ratio of 250 or higher. The cytotoxic activity was also gradually decreased and was totally abolished when one equivalent of iodination was achieved. However, antigenic properties of the cytotoxin were preserved in the iodinated form. When the iodination of the cytotoxin was carried out with a carrier free radiolabeled iodide, the molar ratio was 0.05 resulting in labelling of only 2% of the cytotoxin molecules, which explains the cytotoxicity of the radiolabeled mixture. 相似文献
8.
The population ofP. longirostris along the Mediterranean coast of Israel spends the benthic phase of its life cycle (from body size over 15 mm) on muddy bottom deeper than 45 m. New age groups are recruited within the depth zone of 45–300 m and migrate in both inshore and offshore directions. Inshore migration is limited by unsuitable sandy ground. The limiting line for offshore migration was not found.An age group could be detected during one year within a body size range of TL = 40 mm to TL = 84.5 mm for males and to TL = 102.5 mm for females. Reproductive activity in shallow water, down to a depth of 73 m, takes place during the whole year, while in depths of 150–300 m there is an arrest of reproductive activity from June to August. 相似文献
9.
A simple methematical model describes the invasion of panmictic, sexually reproducing populations by a newly introduced transposon. The model places important constraints on the properties that transposons must have to successfully invade a population and describes the kinetics with which such an invasion will occur. Invasibility conditions serve as a basis for new, detailed scenarios whereby transposon-mediated depression in fitness produces reproductive isolation of populations. These scenarios, in turn, lead to several speculations concerning the role of transposons in evolution. 相似文献
10.
Tatiana I. Gerasimova Yurii V. Ilyin Lev J. Mizrokhi Liliya V. Semjonova Georgii P. Georgiev 《Molecular & general genetics : MGG》1984,193(3):488-492
Summary A family of unstable mutations at the cut locus in Drosophila melanogaster was obtained under the conditions of hybrid dysgenesis (Gerasimova 1981, 1982). The in situ hybridization experiments have shown that, in the original unstable ct
MR2 mutation, the 7B region of the X chromosome (where cut is located) contains a mobile dispersed genetic element, mdg4. All other unstable ct mutations derived from ct
MR2 including visible and lethal alleles and unstable ct
+ reversions, also contain mdg4 in the 7B region. The X chromosomes of the parent strain (wild type) do not contain mdg4 at all. All stable revertants derived from ct
MR2, from other unstable ct mutations, or from ct lethals lost mdg4 from the 7B region. The ct
MR2 X chromosome does not contain P-elements, although a few copies are present in the autosomes. The instability of the ct
MR2./ct
MR2 strain remained at a high level for 50 generations (1.5 years) and then rapidly decreased. A new cross with an MRh12/Cy strain (originally used for dysgenesis induction and containing a number of P-elements) increased the instability to a level exceeding the original one. The data strongly suggest that unstable ct mutations in our system are induced by transpositions of mdg4, possibly activated by P-elements. 相似文献