首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The correlative analysis of diurnal rhythms of cell number and adenylate cyclase cellular activity was performed in the thymus, spleen and peripheral blood of Swiss mice, intact or thymectomized at the age of 3 months. The existence of somehow synchronized diurnal rhythms of cAMP exchange and cell recirculation was found in the peripheral lymphocyte pool and in the thymus. Diurnal rhythm of cAMP synthesis in peripheral lymphocytes was regulated by the thymus. Thymectomy led to desynchronization of recirculating processes and cyclic nucleotide metabolism in immunocompetent cells.  相似文献   

2.
Ichthyoplankton surveys are made in lagoon water bodies of the south-eastern part of Sakhalin (the Vavai-Chibisan system of lakes, Lake Tunaicha, Lake Izmenchivoe) from April until November 2002–2007. Comparative characteristics of ichthyoplankton complexes in the ice-free period is given. In the investigated lagoon lakes, differences in the species composition of the ichthyoplankton by the number and time of appearance of the maxima of abundance of eggs and larvae are noted, and also related to morphological structure and hydrological conditions of water bodies. In lagoon lake Izmenchivoe with a salinity not less than 26‰, the eggs and larvae of marine fishes only takes place while, in Vavai-Chibisan lakes, that of freshwater fishes only takes place. In brackish lake Tunaicha, the lowest number of fish species reproduce. In the Vavai-Chibisan system and in Lake Izmenchivoe, one maximum of abundance of ichthyoplankton in June is recorded and, in Lake Tunaicha, two maxima (the highest in June and less expressed in August) are recorded. Irrespective of the species composition, the ichthyoplankton complexes of lagoon lakes have general traits determined by hydrological conditions of water bodies and by their general origin and geographic situation: prevalence of eggs and larvae of low boreal fish species, the maximum species diversity in the late spring-early summer, and decrease of abundance in cooler years.  相似文献   

3.
Dietary intakes of tomatoes and tomato products containing lycopene have been shown to be associated with decreased risk of chronic diseases such as cancer and cardiovascular diseases in numerous studies. Serum and tissue lycopene levels have also been inversely related to the risk of lung and prostate cancers. Lycopene functions as a very potent antioxidant, and this is clearly a major important mechanism of lycopene action. In this regard, lycopene can trap singlet oxygen and reduce mutagenesis in the Ames test. However, evidence is accumulating for other mechanisms as well. Lycopene at physiological concentrations can inhibit human cancer cell growth by interfering with growth factor receptor signaling and cell cycle progression specifically in prostate cancer cells without evidence of toxic effects or apoptosis of cells. Studies using human and animal cells have identified a gene, connexin 43, whose expression is upregulated by lycopene and which allows direct intercellular gap junctional communication (GJC). GJC is deficient in many human tumors and its restoration or upregulation is associated with decreased proliferation. The combination of low concentrations of lycopene with 1,25-dihydroxyvitamin D3 exhibits a synergistic effect on cell proliferation and differentiation and an additive effect on cell cycle progression in the HL-60 promyelocytic leukemia cell line, suggesting some interaction at a nuclear or subcellular level. The combination of lycopene and lutein synergistically interact as antioxidants, and this may relate to specific positioning of different carotenoids in membranes. This review will focus on the growing body of evidence that carotenoids have unexpected biologic effects in experimental systems, some of which may contribute to their cancer preventive properties in models of carcinogenesis. Consideration of solubility in vitro, comparison with doses achieved in humans by dietary means, interactions with other phytochemicals, and other potential mechanisms such as stimulation of xenobiotic metabolism, inhibition of cholesterogenesis, modulation of cyclooxygenase pathways, and inhibition of inflammation will be considered. This review will point out areas for future research where more evidence is needed on the effects of lycopene on the etiology of chronic disease.  相似文献   

4.
The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.  相似文献   

5.
Using the Karnovsky and Roots modified by E1 Badawi and Schenk's technic for the cholinergic innervation and with the method of Lindvall and Bj?rklund modified by de la Torre and Surgeon for the adrenergic ones, we demonstrate the innervation of each tissular layer, in cervix, corpus and cornua of the uterus of the she-rat in pro-oestrus state. A statistic evaluation is established for the different areas. The density of cholinergic innervation is richer than the adrenergic one. The number of cholinergic fibers is maximum in the cervix. It decreases in corpus and cornua especially in the mucosal and sub-mucosal layers. The density of the muscular nervous network is predominant in the corpus versus the cervix. The number of adrenergic nerves is maximum in corpus it diminishes in the cervix and the cornua. In each region, the muscular adrenergic network domines over the other tissular layers. We confirm statistically morphometric non parametric observations of these other authors.  相似文献   

6.
C-banding patterns of the karyotypes of two closely related wild flax species, Linum austriacum L. (2n = 18) and Linum grandiflorum Desf. (2n = 16), were studied. The karyotypes of both species were similar in the chromosome morphology and size. In each species, metacentric and acrocentric chromosomes (1.7-4.3 microns) and one satellite chromosome were observed. In the karyotypes of the species studied, all homologous chromosome pairs were identified, and quantitative ideograms were constructed. Eight chromosome pairs in the two species had similar C-banding patterns. A low level of intraspecific polymorphism in the intercalary and telomeric C-bands was shown in both species. The results indicate that the genomes of two flax species originated from one ancestral genome with the main chromosome number of 8 or 9. Apparently, the doubling of chromosome number or loss of one chromosome with subsequent redistribution of the chromosome material in the ancestral form resulted in the divergence into two species, L. austriacum L. and L. grandiflorum Desf. A considerable similarity of chromosomes in these species provides evidence for their close phylogenetic relatedness, which makes it possible to place them in one section within the Linum genus.  相似文献   

7.
Melanophores in the arteries of the base of the brain of kittens displayed pronounced variations in size and shape in response to the peripheral electrical stimulation of the vagus and the sympathetic nerves. These melanophores changed their size and shape under the influence of acetylcholine and noradrenaline solutions in vitro too. The present experiments showed melanophores to have a double effector innervation.  相似文献   

8.
The present investigation deals with the effect of testosterone on each of the tissue components of the bursa of Fabricius: the endodermal epithelium, the mesenchyme, and the hemopoietic stem cells. Tissue combination experiments between testosterone-treated endoderm and normal mesenchyme and vice versa have shown that the androgen damages irreversibly the bursal epithelium. The latter is not seeded by hemopoietic stem cells and cannot undergo follicle formation when treated with high doses of testosterone. This occurs even if it is associated with a nontreated bursal mesenchyme. On the contrary, associations of testosterone-treated mesenchyme with normal endoderm result in normal bursa histogenesis. By using an original test of viability for lymphoid cells based on the application of the quail-chick marker system, we demonstrate that disappearance of hemopoietic cells in the endoderm results from their expulsion from the bursa and not from their death in situ. The conspicuous effect of testosterone on the bursa of Fabricius can be related to the levels of androgen receptors found in the organ. Typical cytosol androgen receptors are demonstrated in both bursal endoderm and mesoderm, although the amount in the former is higher. The concentration of binding sites in the bursa is >10 times higher than that in other organs such as lung and small intestine whose development is not affected by testosterone, contrasting with glucocorticosteroid receptor (measured by labeling with dexamethasone) found in the same concentration in all tissues.  相似文献   

9.
A simple case is considered in which the rate of a two-step reaction depends on pH because the intermediate formed in the first step has to gain (or lose) a proton before it can react in the second step, and in which the rate-determining step therefore changes with pH. The curves of reaction rate against pH are shown to be symmetrical, and the sharpest peak possible has a width at half its height of 1.53pH units, i.e. of 2log(3+2 radical2). Any particular curve for this situation proves to be identical with a curve that could be generated for the pH-dependence of a single-step reaction in which the rate is proportional to the concentration of a particular ionic form of a reactant. Curves for the latter situation, however, can have forms impossible for the former case in which the rate-determining step changes, but only if the protonations that activate and deactivate the reactant are co-operative. The peak can then become even sharper, and its width at half its height can fall to 1.14pH units, i.e. to 2log(2+ radical3).  相似文献   

10.
A G Savinov 《Radiobiologiia》1986,26(4):482-487
Opposite changes occur in the intensity of UV-fluorescence (UVF) in irradiated (0.1 Gy and 5.0 Gy) HeLa cells. The radiometric study has demonstrated that there is a correlation between the number of tryptophan-containing proteins and UVF intensity in nonirradiated and irradiated (5.0 Gy) cells during culture growth. Such a correlation was absent in cells exposed to 0.1 Gy radiation. Low radiation doses (0.1 Gy) have maximum action on cytoplasm membrane fluorescence. Low-level radiation changes the intensity of the ANS probe fluorescence connected with cell membranes, and the intensity of the cell protein UVF. High radiation doses increase and low doses decrease the probe fluorescence.  相似文献   

11.
Flocks of birds are highly variable in shape in all contexts (while travelling, avoiding predation, wheeling above the roost). Particularly amazing in this respect are the aerial displays of huge flocks of starlings (Sturnus vulgaris) above the sleeping site at dawn. The causes of this variability are hardly known, however. Here we hypothesise that variability of shape increases when there are larger local differences in movement behaviour in the flock. We investigate this hypothesis with the help of a model of the self-organisation of travelling groups, called StarDisplay, since such a model has also increased our understanding of what causes the oblong shape of schools of fish. The flocking patterns in the model prove to resemble those of real birds, in particular of starlings and rock doves. As to shape, we measure the relative proportions of the flock in several ways, which either depend on the direction of movement or do not. We confirm that flock shape is usually more variable when local differences in movement in the flock are larger. This happens when a) flock size is larger, b) interacting partners are fewer, c) the flock turnings are stronger, and d) individuals roll into the turn. In contrast to our expectations, when variability of speed in the flock is higher, flock shape and the positions of members in the flock are more static. We explain this and indicate the adaptive value of low variability of speed and spatial restriction of interaction and develop testable hypotheses.  相似文献   

12.
The content of urea was studied in protein-free filtrates of the liver kidneys, skeletal muscles, myocardium, spleen, brain tissues and blood serum as well as in urine of 1, 3, 6, 12 and 24-month rats. It is shown that at the age of 6 months the content of urine in most tissues under study is significantly decreased (by 42-73%), at the age of 12 months in the spleen and at the age of 24 months in the brain tissues as compared to the one-month animals. The level of urine decrease in the liver and brain tissues of 24-month animals is less pronounced than in other tissues, that corresponds to age peculiarities of their protein metabolism. A decrease of blood consumption per weight unit and a relative increase in the amount of nitrogen excreted with urine are observed with ageing. The arginase activity in the liver decreases essentially only in 3-month animals. A conclusion is drawn that peculiarities of food consumption and the character of changes in the urea content in tissues and urine are adaptation manifestation of an age decrease in the intensity of nitrogen metabolism and protein demand of the organism.  相似文献   

13.
The cenofloras of moss tundras, dryas tundras, and cryophytic grassy bogs of Subarctic Yamal, Taimyr, and Yakutia have been compared in such parameters as activity and species richness of their ecological groups. Comparison of the three cenofloras of subarctic tundras in conditions of heat and moisture has shown that the habitats of Yamal noticeably differ from the habitats of Taimyr and Yakutia. In Yamal, the conditions are warmer in all the habitats except grassy bogs in the zone of typical tundras. Most habitats in Yamal are drier. The hydrothermal conditions of Taimyr and Yakutia are similar. The differences arise as the climate becomes increasingly more continental from west to east.  相似文献   

14.
Summary MAO of the brain was investigated histochemically in mice, rats, guinea pigs and rabbits. Fresh frozen sections were subjected to the tryptamine-tetrazolium method by Glenner, Burtner and Brown (1957).MAO activity of the brain of 4 animal species is generally similar with respect to its pattern of distribution. However, the intensity of enzyme action of the brain as a whole differs somewhat in animal species, being highest in guinea pigs, intermediate in rats and lowest in mice and rabbits. The enzyme action occurs mainly in the neuropil of the cerebral grey matter, while weak or negative activity is generally observed in the white matter excepting the tractus retroflexus of Meynert.The marked activity is encountered in the interpeduncular nucleus, locus coeruleus, area postrema, dorsal nucleus of the vagus nerve, hypothalamus, habenular nuclei and midline nuclear group of the thalamus, nucleus of the brachium conjunctivum, and central grey matter. The enzyme activity is weak or negative in the neocortex, striatum, mamillary body, thalamic nuclei (excepting the habenula and midline nuclear group), subthalamic nucleus, substantia nigra, red nucleus and nuclei of the somatic cranial nerves.The possible function and significance of MAO in the brain were discussed particularly by comparing the sites of this enzyme with those of succinic dehydrogenase and cytochrome oxidase, and the inverse relation between these enzymes was suggested.  相似文献   

15.
青蒿素生物合成机理研究现状   总被引:10,自引:1,他引:9  
赵兵  王玉春  欧阳藩   《广西植物》1999,19(2):154-158
本文总结了目前有关青蒿素生物合成机理方面的研究,主要包括青蒿素生物合成中生理因子的影响,青蒿素生物合成中间体及前体,青蒿素生物合成细胞定位等。指出了存在的一些问题及今后的研究发展前景。  相似文献   

16.
A short review presented deals with the history of biochemistry development in the western regions of Ukraine. Two principal biochemical schools were founded here by J. Parnas (1884-1949) and S. Gzhytskiy (1900-1976). While most of the students and collaborators of Prof. J. Parnas left for Poland and other western states, those ones of Prof. S. Gzhytskiy stayed in Lviv and other scientific centers of Ukraine. In 1979 Prof. S. Kusen (one of Gzhytskiy's former students and collaborators) and Prof. G. Shavlovsky headed two scientific departments founded in Lviv at O. V. Palladin Institute of Biochemistry. This event could be considered as the beginning of modern biochemistry development in the western regions of Ukraine. Since 1992 in Lviv there exists the Division of Regulatory Cell Systems of O. V. Palladin Institute of Biochemistry of the National Academy of Sciences of Ukraine headed since 1995 by Prof. R. Stoika. Four Departments work in the structure of this Division: 1) the Department of Biochemistry of Cell Differentiation headed in 1979-1997 by S. Kusen and since 1997 by L. Drobot; 2) the Department of Regulation of Cell Proliferation created in 1993 and headed by R. Stoika; 3) the Department of Biochemical Genetics created in 1988 and headed by A. Sibirny; 4) the Department of Regulation of Synthesis of Low Molecular Compounds headed in 1979-1996 by G. Shavlovsky and since 1996 by D. Fedorovych. Division of Regulatory Cell Systems is presently the leading scientific center in Ukraine in the study of the biochemical mechanisms of proliferation, differentiation and apoptosis of normal and tumour cells and in the development of effective biotechnological processes for obtaining the biologically active substances using yeast. Numerous publications of its collaborators in the high impact factor scientific magazines as well as the realisation of the international grants confirm this statement. Taking into account the high level of scientific research and availability of highly skilled scientists at the Division in 1999 the Presidium of the National Academy of Sciences of Ukraine took a resolution to transform the Division into the Institute of Cell Biology of the National Academy of Sciences of Ukraine, which was founded in 2000 on the basis of the Division.  相似文献   

17.
The metabolism of nuclear phospholipid acyl components of liver in uneven-aged rats was studied in vitro under different dietary fat implications. The activity of phospholipases A1 and A2 in the nuclei was found to sharply increase in animals pretreated with excess of fat. The incorporation of labelled palmitic, oleic, linoleic and arachidonic acid into nuclear phospholipids is under control of age and diet manipulations. The observed changes in the level of fatty acids metabolism are more pronounced in cell nuclei of the young rat liver. The lipid composition of cell nuclei in the test 3-month old animals does not differ from that of the control animals. At the same time dietary implications induce deep changes in the composition of nuclear lipids in 24-months old animals.  相似文献   

18.
Dependence of the temporal structure of the spike discharge of a neuron in a weakly interacting network on the characteristics of excitatory and inhibitory input flows and on cell parameters was analyzed by a mathematical model. The intensity of communication between individual neurons corresponded to the intensity of synaptic communication between real spinal neurons. The temporal course of trace and accommodation processes in the model was similar to that of these processes in real spinal neurons. Connection of inhibitory inputs and an increase in the intensity of their influences were shown to be equivalent to a decrease in the intensity of excitatory input flows. Changes in cell parameters had a significant effect on the spike discharge only in the case of weak input influences (the ratio of the amplitude of the combined ESP evoked by the input spike train to the threshold value of membrane potential at rest was about 1.2:1.0 to 1.4:1.0). An increase in the input flow intensity led to considerable reorganization of the firing pattern: Mean values of interspike intervals and their fluctuations were reduced, histograms of interspike intervals became more symmetrical, and periodic waves appeared on the autocorrelation histograms. It is concluded on the basis of these results and of data in the literature that the main factor determining reorganization of the temporal structure of unit activity in a network of weakly interacting cells is the intensity of the input flow.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 2, pp. 199–207, March–April, 1980.  相似文献   

19.
20.
Nitrosoderivatives of the nitrodiphenyl ether herbicides (nitrofen, bifenox) have been studied. UV irradiation in different organic solvents gives degradation products. In buffered aqueous media, in the presence of chloroplasts and spin traps such as DMPO, hydroxy and peroxy radicals have been characterized.

In organic media and in the presence of spin traps such as DMPO, PBN, 4-POBN, solvent radicals (CHCIl2, CCI3, CH2O) have been formed.

Nitro-derivatives have been studied under UV irradiation and in the presence of tetramethylethylene (TME), alkenylhydroxylamines are formed which autoxidize in nitroxide radicals. The formation of the stable nitroxide radical occurs in the dark process after continuous irradiation. The intensity of the signal decreases strongly when a new irradiation is applied. Radical species, with analogous ESR spectral characteristics are formed on reaction with nitrodiphenyl ethers and fatty acids.

The reactivity of these herbicides in micellar media (SDS, Brij 35, and CTAB) has been investigated. The kinetics of formation of the ESR signal corresponding to the photoreduction of the nitrodiphenyl ether in the presence of TME behave differently in a micellar environment as compared to solution. The intensity of the formation of the nitroxide increases under irradiation and decreases in the dark; the rotational correlation time tc has been determined for each type of micelle.

Synthetic nitrosodiphenyl ether made by the reduction of nitrodiphenyl ether using hydrogen gas and PtO2 as a catalyst gives the corresponding amine, which is oxidized with rneta-chloroperbenzoic acid (m.CPBA). The nitrosodiphenyl ether in the presence of soja azolectin liposorne containing a fluorescent probe has been analysed. When this synthetic nitrosodiphenyl ether is added to a medium containing soja azolectin liposomes and a carboxyfluorescein, fluorescent probe placed inside the liposornes, a rapid increase in the fluorescence of the medium is observed. The nitrosodiphenyl ether induce a break in the liposorne membrane.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号