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Svetlana V. Butsuk Boris I. Bessonov 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1981,141(2):277-282
Summary A direct current electric field up to 3 mV/ cm was recorded in 33 sea water around the fishMyoxocephalus brandti, Hexogrammos octogrammos, Enophrys diceraus, Pleuronectes stellatus, Bathimaste r derjugini, Sebastes scorpaeniformis. The body surface potentials were positive in relation to the external and internal media; they attained 10 mV and slowly varied near the mean value at every point. The potentials at the surface points of individual skin sections adjoining the oral and branchial cavities, the anal orifice and peripheral fin sections were normally characterized by polarities opposite to those of body surface potentials (in sea water they were negative in relation to the external medium).When placed in sea water during their fresh water cycle, the salmonOncorhynchus keta and the fresh water fishSalvelinus alpinus andMisgurnus fossilis had no d.c. field.In fresh water containing less than 0.03 salt, a d.c. field up to 25 mV/cm was recorded around all the above mentioned species. The potentials had an opposite polarity to that recorded in sea water.The distribution of potentials over the fish surface depends on the species. The potentials at some points of the body surfaces were found to vary when other fish or metal objects were placed in the aquarium.The parameters of the direct current electric field generated by a whole fish and by isolated skin pieces were identical and varied by the same law with changed medium salinity. Thus it may be assumed that the d.c. electric field around the fish is produced by active electrogenic ion transport mechanisms localized in the skin. 相似文献
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Kyrylo A. Pyrshev Semen O. Yesylevskyy Alexander P. Demchenko 《Biochemical and biophysical research communications》2019,508(4):1139-1144
New technique of detecting lateral heterogeneity of the plasma membrane of living cells by means of membrane-binding fluorescent dyes is proposed. The kinetics of dye incorporation into the membrane or its lateral diffusion inside the membrane is measured and decomposed into exponential components by means of the Maximum Entropy Method. Two distinct exponential components are obtained consistently in all cases for several fluorescent dyes, two different cell lines and in different types of experiments including spectroscopy, flow cytometry and fluorescence recovery after photobleaching. These components are attributed to the liquid-ordered and disordered phases in the plasma membrane of studied cells in their dynamic equilibrium. 相似文献
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Bessonov AN Gur'nev FA Kuznetsova IM Takemoto JY Turoverov KK Malev VV Shchagina LV 《Tsitologiia》2004,46(7):628-633
The effect of filamentous (F) actin on the channel-forming activity of syringomycin E (SRE) in negatively charged and uncharged bilayer lipid membranes (BLM) was studied. F-actin did not affect the membrane conductance in the absence of SRE. No changes in SRE-induced membrane conductance were observed when the above agents were added to the same side of BLM. However, the opposite side addition of F-actin and SRE provokes a multiple increase in membrane conductance. The similar voltage dependence of membrane conductance, equal values of single channel conductance and the effective gating charge of the channels upon F-actin action suggests that the actin-dependent increase in BLM conductance may result from an increase in the number of opened SRE-channels. BLM conductance kinetics depends on the sequence of SRE and F-actin addition, suggesting that actin-dependent rise of conductance may be induced by BLM structural changes that follow F-actin adsorption. F-actin exerted similar effect on membrane conductance of both negatively charged and uncharged bilayers, as well as on conductance of BLM with high ionic strength bathing solution, suggesting the major role for hydrophobic interactions in F-actin adsorption on lipid bilayer. 相似文献
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Nikolai Bessonov Michael Levin Nadya Morozova Natalia Reinberg Alen Tosenberger Vitaly Volpert 《PloS one》2015,10(2)
We present here a new model of the cellular dynamics that enable regeneration of complex biological morphologies. Biological cell structures are considered as an ensemble of mathematical points on the plane. Each cell produces a signal which propagates in space and is received by other cells. The total signal received by each cell forms a signal distribution defined on the cell structure. This distribution characterizes the geometry of the cell structure. If a part of this structure is removed, the remaining cells have two signals. They keep the value of the signal which they had before the amputation (memory), and they receive a new signal produced after the amputation. Regeneration of the cell structure is stimulated by the difference between the old and the new signals. It is stopped when the two signals coincide. The algorithm of regeneration contains certain rules which are essential for its functioning, being the first quantitative model of cellular memory that implements regeneration of complex patterns to a specific target morphology. Correct regeneration depends on the form and the size of the cell structure, as well as on some parameters of regeneration. 相似文献
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We have evaluated the effects of the proline homologue Aze (1) (azetidine-2-carboxylic acid) on growth of Escherichia coli strains used to over-express recombinant forms of murine myelin basic protein (rmMBP), and on the degree of misincorporation. Addition of Aze to minimal media resulted in severe diminution of growth rate, but rmMBP could still be produced and purified. Mass spectrometry indicated that a detectable proportion of the rmMBP produced had incorporated Aze instead of proline (Pro), to a maximum of three of eleven possible sites. Molecular modelling of a proline-rich region of rmMBP illustrated that the misincorporation of Aze at any site would cause a severe bend in the polypeptide chain, and that multiple Pro → Aze substitutions would completely disrupt a poly-proline type II structure that has been conjectured to be functionally significant. 相似文献
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Sheikh N Batusic DS Dudas J Tron K Neubauer K Saile B Ramadori G 《American journal of physiology. Gastrointestinal and liver physiology》2006,291(3):G482-G490
In this work, we used two rat models, partial hepatectomy (PH) and CCl(4) administration, to study the changes in iron pathways in response to hepatic damage. Liver injury induced changes in the hepatic gene expression of hepcidin, hemojuvelin (Hjv), several other proteins of iron metabolism, and several cytokines such as IL-1beta, IL-6, TNF-alpha, and IFN-gamma. Hepcidin gene expression was upregulated between 4 and 8 h with a maximum up to 16 h after surgery. However, Hjv gene expression was downregulated at the same time. An early upregulation of hepcidin (3 h) and downregulation of Hjv gene expression was found after CCl(4) administration. Transferrin receptor 1 and ferritin H gene expression was upregulated, whereas ferroportin 1 gene expression was downregulated. Hepatic IL-6 gene expression was upregulated early after PH and reached maximum 8 h after the PH. In CCl(4)-induced liver injury, IL-6, IL-1beta, TNF-alpha, and IFN-gamma upregulation were found at the maximum 12 h after the administration of the toxin. Treatment of isolated rat hepatocytes with IL-6 and, to a lesser extent, with IL-1beta but not with TNF-alpha or IFN-gamma dose dependently upregulated hepcidin and downregulated Hjv gene expression. In hepatic damage, changes of the hepatic gene expression of the main proteins involved in iron metabolism may be induced by locally synthesized mediators. 相似文献
10.
A major determinant of plant architecture is the arrangement of branches around the stem, known as phyllotaxis. However, the
specific form of branching conditions is not known. Here we discuss this question and suggest a branching model which seems
to be in agreement with biological observations.
Recently, a number of models connected with the genetic network or molecular biology regulation of the processes of pattern
formation appeared. Most of these models consider the plant hormone, auxin, transport and distribution in the apical meristem
as the main factors for pattern formation and phyllotaxis. However, all these models do not take into consideration the whole
plant morphogenesis, concentrating on the events in the shoot or root apex. On the other hand, other approaches for modeling
phyllotaxis, where the whole plant is considered, usually are mostly phenomenological, and due to it, do not describe the
details of plant growth and branching mechanism.
In this work, we develop a mathematical model and study pattern formation of the whole, though simplified, plant organism
where the main physiological factors of plant growth and development are taken into consideration. We model a growing plant
as a system of intervals, which we will consider as branches. We assume that the number and location of the branches are not
given a priori, but appear and grow according to certain rules, elucidated by the application of mathematical modeling.
Four variables are included in our model: concentrations of the plant hormones auxin and cytokinin, proliferation and growth
factor, and nutrients—we observe a wide variety of plant forms and study more specifically the involvement of each variable
in the branching process. Analysis of the numerical simulations shows that the process of pattern formation in plants depends
on the interaction of all these variables. While concentrations of auxin and cytokinin determine the appearance of a new bud,
its growth is determined by the concentrations of nutrients and proliferation factors. Possible mechanisms of apical domination
in the frame of our model are discussed. 相似文献