排序方式: 共有96条查询结果,搜索用时 359 毫秒
31.
Vera Nagorskaya Anatoliy Reunov Larisa Lapshina Viktoriya Davydova Irina Yermak 《Virologica Sinica》2014,(4)
The effect of chitosan on the development of infection caused by Tobacco mosaic virus(TMV) in leaves of Nicotiana tabacum L. cv. Samsun has been studied. It was shown that the infectivity and viral coat protein content in leaves inoculated with a mixture of TMV(2 μg/mL) and chitosan(1 mg/mL) were lower in the early period of infection(3 days after inoculation), by 63% and 66% respectively, than in leaves inoculated with TMV only. Treatment of leaves with chitosan 24 h before inoculation with TMV also caused the antiviral effects, but these were less apparent than when the virus and polysaccharide were applied simultaneously. The inhibitory effects of the agent decreased as the infection progressed. Inoculation of leaves with TMV together with chitosan considerably enhanced the activity of hydrolases(proteases, RNases) in the leaves, in comparison with leaves inoculated with TMV alone. Electron microscope assays of phosphotungstic acid(PTA)-stained suspensions from infected tobacco leaves showed that, in addition to the normal TMV particles(18 nm in diameter, 300 nm long), these suspensions contained abnormal(swollen, "thin" and "short") virions. The highest number of abnormal virions was found in suspensions from leaves inoculated with a mixture of TMV and chitosan. Immuno-electron microscopy showed that "thin" virus particles, in contrast to the particles of normal diameter, lost the ability to bind to specific antiserum. It seems that the chitosan-induced activation of hydrolases stimulates the intracellular degradation of TMV particles and hence hydrolase activation may be considered to be one of the polysaccharide-mediated cellular defense mechanisms that limit virus accumulation in cells. 相似文献
32.
V. N. Davydova V. P. Nagorskaya V. I. Gorbach A. A. Kalitnik A. V. Reunov T. F. Solov’eva I. M. Ermak 《Applied Biochemistry and Microbiology》2011,47(1):103-108
Enzymatic (the action of lysozyme) and chemical (the action of hydrogen peroxide) hydrolysis of chitosans with various degree
of acetylation (DA)—25, 17, and 1.5%—was performed. Purification and fractioning of the hydrolysis products were performed
using dialysis, ultrafiltration, and gel-penetrating chromatography. Low-molecular (LM) derivatives of the polysaccharide
with molecular masses from 17 to 2 kDa were obtained. The study of their antiviral activity against the tobacco mosaic virus
(TMV) showed that these samples inhibited the formation of local necroses induced by the virus for 50–90%. The antiviral activity
of the LM chitosans significantly increased with the lowering of their polymerization degree. Furthermore, the products of
the enzymatic hydrolysis possessed lower activity than the chitosan samples obtained as a result of chemical hydrolysis. It
was revealed that the exhibition of the antiviral activity weakly depended on the degree of acetylation of the samples. 相似文献
33.
Ultrastructural examination of tobacco mosaic virus-induced local lesions growing in Datura stramonium leaves is carried out. It is demonstrated that, in the central area of the lesions, the cell response to viral invasion is
not uniform. Most cells exhibited an acute hypersensitive reaction (HR) and underwent rapid and complete necrosis. However,
some cells, despite considerable virus accumulation and immediate contact with completely collapsed cells, maintained a certain
degree of structural integrity. Analysis performed showed that the proportion of collapsed and uncollapsed cells in the lesion
centre 3 to 5 days after infection essentially did not change. These data suggest that the absence of HR in some cells in
the lesion centre is not due to an early stage of infection but is likely caused by cell tolerance of the virus. 相似文献
34.
Nitric Oxide Synthase Expression in Glial Cells: Suppression by Tyrosine Kinase Inhibitors 总被引:4,自引:0,他引:4
Douglas L. Feinstein Elena Galea Jennifer Cermak Punita Chugh Liubov Lyandvert Donald J. Reis 《Journal of neurochemistry》1994,62(2):811-814
Abstract: Rat brain glial cells have the capacity to express a calcium-independent form of nitric oxide synthase (iNOS). To test if iNOS induction required tyrosine kinase activity, we made use of genistein, a selective inhibitor of tyrosine kinases. In both primary astrocyte cultures and C6 glioma cells, the presence of genistein prevented both lipopolysaccharide- and cytokine-induced NOS activity in a dose-dependent manner. The presence of tyrphostin-25 (10 µ M ), which is highly specific for tyrosine kinases, also blocked iNOS induction. Additional characterization showed that genistein blocked iNOS induction in a dose-dependent manner (IC50 of ∼ 40 µ M ), that the continuous presence of genistein was not necessary to observe inhibition, and that preincubation with genistein led to higher levels of inhibition than the simultaneous addition of genistein and inducers. The decrease in iNOS activity due to genistein was accompanied by a decrease in iNOS mRNA level as detected by a specific PCR assay. These results indicate that induction of astroglial iNOS expression requires tyrosine kinase activity. 相似文献
35.
Alexandru Movila Helen V. Dubinina Natalia Sitnicova Liubov Bespyatova Inga Uspenskaia Galina Efremova Ion Toderas Andrey N. Alekseev 《Experimental & applied acarology》2014,63(1):65-76
Characterizing the tick-borne microorganism communities of Ixodes ricinus (sheep tick) and Ixodes persulcatus (taiga tick) from the I. ricinus species complex in distinct geographical regions of Eastern Europe and European Russia, we demonstrated differences between the two ticks. Taiga ticks were more frequently mono- and co-infected than sheep ticks: 24.4 % (45/184 tested ticks) versus 17.5 % (52/297) and 4.3 % (8/184) versus 3.4 % (10/297), respectively. Ginsberg co-infection index values were significant at the various sites. Diversity of the tick-borne microorganism communities was estimated by the Shannon index, reaching values of 1.71 ± 0.46 and 1.20 ± 0.15 at the sheep-tick and the taiga-tick harbored sites, respectively. Richness of the tick-borne microorganism community in the sheep tick collection sites was about twice the value of the taiga tick collection sites. Future investigations are warranted to further characterize the peculiarities of the tick-borne microorganism communities among the ticks of the Ixodes ricinus complex. 相似文献
36.
Possible mechanisms of action of weak combined magnetic fields on biological systems have been discussed in terms of quantum
mechanics. The approaches proposed make it possible to solve the problem of the failure to compare the energy of active factors
with the energy of thermal motion (kT problem). A mechanism of action of combined magnetic fields on biosystems has been proposed. 相似文献
37.
DI Osolodkin LI Kozlovskaya VA Palyulin VM Pentkovski GG Karganova NS Zefirov 《Biochemical and biophysical research communications》2012,423(2):207-211
Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca(2+) oscillation in pancreatic β-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca(2+) oscillation we designed and conducted experiments in intact primary pancreatic β-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic β-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca(2+) indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca(2+) oscillation. The pattern of glucose-induced Ca(2+) oscillation in the nucleus and cytosol was similar. The reduction of Ca(2+) oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca(2+) amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic β-cells. 相似文献
38.
Liubov Volkova Lauren T. Bennett Andrew Merchant Michael Tausz 《Trees - Structure and Function》2010,24(2):351-362
We examined the responses of two tree fern species (Dicksonia antarctica and Cyathea australis) growing under moderate and high light regimes to short-term water deficit followed by rewatering. Under adequate water supply,
morphological and photosynthetic characteristics differed between species. D. antarctica, although putatively the more shade and less drought adapted species, had greater chlorophyll a/b ratio, and greater water use efficiency and less negative δ13C. Both species were susceptible to water deficit regardless of the light regime showing significant decreases in photosynthetic
parameters (A
max, V
cmax, J
max) and stomatal conductance (g
s
) in conjunction with decreased relative frond water content (RWC) and predawn frond water potential (Ψpredawn). During the water deficit period, decreases in g
s
in both species started one day later, and were at lower soil water content, under moderate light compared with high light.
D. antarctica under moderate light was more vulnerable to drought than all other plants as was indicated by greater decreases in Ψpredawn, lowest stomatal conductance, and photosynthetic rates. Both tree fern species were able to recover after a short but severe
water stress. 相似文献
39.
Alexander M. Kulminski Irina Culminskaya Konstantin G. Arbeev Svetlana V. Ukraintseva Eric Stallard Liubov Arbeeva Anatoli I. Yashin 《Aging cell》2013,12(2):237-246
The inherent complexity of aging‐related traits can temper progress in unraveling the genetic origins of healthspan. We focus on two generations in the Framingham Heart Study, the original (FHS) and offspring (FHSO) cohorts, to determine whether aging‐related processes in changing environments can substantially impact the role of lipid‐related genes discovered in candidate gene (the apolipoprotein E (APOE) e2/3/4 polymorphism) and genome‐wide (the APOB rs1042034 (C/T)) studies, in regulation of total cholesterol (TC) and onset of cardiovascular disease (CVD). We demonstrate that the APOE e4 allele and APOB CC genotype can play detrimental, neutral, and protective sex‐specific roles in the etiology of CVD at different ages and in different environments. We document antagonistic roles for the e4 allele in the onset of CVD characterized by detrimental effects at younger ages (RR≤ 75 years = 1.49, P = 7.5 × 10?4) and protective effects at older ages (RR76+years = 0.77, P = 0.044) for FHS participants. We found that disregarding the role of aging erroneously nullifies the significant effects of the e4 allele in this sample (RR = 0.92, P = 0.387). The leading biogenetic pathways mediating genetic effects on CVD may be more relevant to lipid metabolism for APOB than APOE. Aging‐related processes can modulate the strength of genetic associations with TC in the same individuals at different chronological ages. We found substantial differences in the effects of the same APOE and APOB alleles on CVD and TC across generations. The results suggest that aging‐related processes in changing environments may play key roles in the genetics of healthspan. Detailed systemic integrative analyses may substantially advance the progress. 相似文献
40.
Lapshina LA Nagorskaya VP Reunov AV Barabanova AO Shevchenko NM Yermak IM Zvyagintseva TN Elyakova LA 《Biochemistry. Biokhimii?a》2011,76(4):462-466
The activities of hydrolases (acid phosphatase, RNase, and proteases) in healthy and tobacco mosaic virus-infected leaves
of Nicotiana tabacum L. var. Samsun, both untreated and treated with polysaccharides (PS) (1,3;1,6-β-D-glucan, fucoidan, and κ/β-carrageenan),
were determined. The PS lead to substantial increase in the hydrolase level. The percentage of viral particles undergoing
destructive change also increases in leaves treated with PS 24 h before infection. We suppose that the PS-mediated hydrolase
activation promotes intracellular destruction of the viral particles and, thus, comprises one of the PS-induced protective
mechanisms limiting intracellular viral accumulation. 相似文献