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41.
N. R. Meichik N. I. Popova Yu. I. Nikolaeva I. P. Yermakov A. N. Kamnev 《Applied Biochemistry and Microbiology》2011,47(2):176-181
Research into ion-exchange properties of cell walls isolated from thallus of red seaweed Phyllophora crispa was carried out. Ion-exchange capacity and the swelling coefficient of the red alga cell walls were estimated at various
pH values (from 2 to 12) and at constant ionic strength of a solution (10 mM). It was established that behavior of cell walls
as ion-exchangers is caused by the presence in their matrix of two types of cation-exchange groups and amino groups. The amount
of the functional group of each type was estimated, and the corresponding values of pK
a
were calculated. It can be assumed that ionogenic groups with pK
a
∼5 are carboxyl groups of uronic acids, and ionogenic groups with pK
a
∼7.5 are carboxyl groups of the proteins. Intervals of pH in which cation-exchange groups are ionized and can take part in
exchange reactions with cations in the environment are defined. It was found that protein was a major component of cell wall
polymeric matrix because its content was 36%. 相似文献
42.
In the Early Carboniferous-Bashkirian the most diverse ammonoid assemblages were associated with deep-water settings of the
outer shelf and the carbonate platform slope. At the end of the Early Bashkirian, ammonoid assemblages of basins of the eastern
slope of the South Urals were associated with shallow-water settings and bioherm buildups, which probably contributed to their
endemism. New species of the genera Neogoniatites, Schartymites, and Stenoglaphyrites are described from localities of the eastern slope of the South Urals. 相似文献
43.
S. V. Nikolaeva 《Paleontological Journal》2011,45(5):501-509
The history of the taxonomy and classification of the Famennian genus Praeglyphioceras Wedekind, 1908 and the family Praeglyphioceratidae are discussed. The sutural ontogeny of this genus, which is examined for
the first time for two species of the genus, supports the high taxonomic rank of praeglyphioceratids. This family is mostly
related to primitive Prionoceratoidea. A new species, Praeglyphioceras korobkovi sp. nov., is described from the delphinus Zone (Prolobites-Platyclymenia Genozone) of the Aktyubinsk Region of Kazakhstan. 相似文献
44.
Rabi SA O'Connell KA Nikolaeva D Bailey JR Jilek BL Shen L Page KR Siliciano RF Blankson JN 《Journal of virology》2011,85(2):979-986
Elite controllers or suppressors (ES) are a group of HIV-1-infected individuals who maintain viral loads below the limit of detection of commercial assays for many years. The mechanisms responsible for this remarkable control are under intense study, with the hope of developing therapeutic vaccines effective against HIV-1. In this study, we addressed the question of the intrinsic susceptibility of ES CD4(+) T cells to infection. While we and others have previously shown that CD4(+) T cells from ES can be infected by HIV-1 isolates in vitro, these studies were confounded by exogenous activation and in vitro culture of CD4(+) T cells prior to infection. In order to avoid the changes in chemokine receptor expression that have been associated with such exogenous activation, we infected purified CD4(+) T cells directly after isolation from the peripheral blood of ES, viremic patients, and uninfected donors. We utilized a green fluorescent protein (GFP)-expressing proviral construct pseudotyped with CCR5-tropic or CXCR4-tropic envelope to compare viral entry using a fluorescence resonance energy transfer-based, single-round virus-cell fusion assay. The frequency of productive infection was also compared by assessing GFP expression. CD4(+) T cells from ES were as susceptible as or more susceptible than cells from viremic patients and uninfected donors to HIV-1 entry and productive infection. The results of this physiological study strongly suggest that differences in HIV-1 entry and infection of CD4(+) T cells alone cannot explain the elite control of viral replication. 相似文献
45.
Mandal MN Moiseyev GP Elliott MH Kasus-Jacobi A Li X Chen H Zheng L Nikolaeva O Floyd RA Ma JX Anderson RE 《The Journal of biological chemistry》2011,286(37):32491-32501
α-Phenyl-N-tert-butylnitrone (PBN), a free radical spin trap, has been shown previously to protect retinas against light-induced neurodegeneration, but the mechanism of protection is not known. Here we report that PBN-mediated retinal protection probably occurs by slowing down the rate of rhodopsin regeneration by inhibiting RPE65 activity. PBN (50 mg/kg) protected albino Sprague-Dawley rat retinas when injected 0.5-12 h before exposure to damaging light at 2,700 lux intensity for 6 h but had no effect when administered after the exposure. PBN injection significantly inhibited in vivo recovery of rod photoresponses and the rate of recovery of functional rhodopsin photopigment. Assays for visual cycle enzyme activities indicated that PBN inhibited one of the key enzymes of the visual cycle, RPE65, with an IC(50) = 0.1 mm. The inhibition type for RPE65 was found to be uncompetitive with K(i) = 53 μm. PBN had no effect on the activity of other visual cycle enzymes, lecithin retinol acyltransferase and retinol dehydrogenases. Interestingly, a more soluble form of PBN, N-tert-butyl-α-(2-sulfophenyl) nitrone, which has similar free radical trapping activity, did not protect the retina or inhibit RPE65 activity, providing some insight into the mechanism of PBN specificity and action. Slowing down the visual cycle is considered a treatment strategy for retinal diseases, such as Stargardt disease and dry age-related macular degeneration, in which toxic byproducts of the visual cycle accumulate in retinal cells. Thus, PBN inhibition of RPE65 catalytic action may provide therapeutic benefit for such retinal diseases. 相似文献
46.
Meĭchik NR Popova NI Nikolaeva IuI Ermakov IP Kamnev AN 《Prikladnaia biokhimiia i mikrobiologiia》2011,47(2):194-200
Research into ion-exchange properties of cell walls isolated from thallus of red seaweed Phyllophora crispa was carried out. Ion-exchange capacity and the swelling coefficient of the red alga cell walls were estimated at various pH values (from 2 to 12) and at constant ionic strength of a solution (10 mM). It was established that behavior of cell walls as ion-exchangers is caused by the presence in their matrix of two types of cation-exchange groups and amino groups. The amount of the functional group of each type was estimated, and the corresponding values of pK(a) were calculated. It can be assumed that ionogenic groups with pK(a) -5 are carboxyl groups of uronic acids, and ionogenic groups with pK(a) -7.5 are carboxyl groups of the proteins. Intervals of pH in which cation-exchange groups are ionized and can take part in exchange reactions with cations in the environment are defined. It was found that protein was a major component of cell wall polymeric matrix because its content was 36%. 相似文献
47.
P. Yu. Voronin Z. F. Rakhmankulova S. N. Maevskaya M. K. Nikolaeva E. V. Shuiskaya 《Russian Journal of Plant Physiology》2014,61(1):131-135
Detached leaf is in the state of increasing water deficit; it is a good experimental model for looking into the hardening effect of adaptation of eight-day-old maize (Zea mays L.) seedlings to short-term drought (five days without watering). The light stage of photosynthesis and photosynthetic CO2/H2O exchange in detached leaves were studied. Specific surface density of leaf tissue (SSDL), the content of chlorophylls a and b, proline, MDA as well as photosynthetic parameters: quantum yield of photosystem II fluorescence, assimilation of CO2, and transpiration at room temperature and light saturation (density of PAR quantum flux of 2000 μmol/(m2 s)) at normal and half atmospheric CO2 concentration were determined. The leaves of seedlings exposed to short-term drought differed from control material by a greater SSDL and higher content of proline. The hardening effect of the stress agent on the dark stage of photosynthesis was detected; it was expressed in the maintenance of the higher photosynthetic CO2 assimilation against control material due to the elevation of stomatal conductance for CO2 diffusing into the leaf. Judging from the lack of differences in the MDA content, short-term drought did not injure photosynthetic membranes. In detached leaves of experimental maize seedlings, photosynthesis was maintained on a higher level than in control material. 相似文献
48.
I. A. Popov M. I. Indeikina S. I. Pekov N. L. Starodubtseva A. S. Kononikhin M. I. Nikolaeva E. N. Kukaev Yu. I. Kostyukevich S. A. Kozin A. A. Makarov E. N. Nikolaev 《Molecular Biology》2014,48(4):607-614
Recently, amyloid-beta (Aβ) phosphorylation at position 8 has been shown to be associated with pathogenesis of Alzheimer’s disease. Since the modification occurs in the key fragment of the metal-binding domain of Aβ and should seriously affect the interaction of pS8-Aβ with zinc ions, this isoform may be a potential precursor of pathogenic oligomer forms of Aβ. Hence the level of pS8-Aβ in human biological fluids (blood, urine, cerebrospinal fluid) may reflect various stages of pathogenesis of the Alzheimer’s disease. The aim of the work was to develop a prototype of an analytical method for quantitative determination of the level of pS8-Aβ isoform in binary mixtures with native Aβ in order to further use it to estimate the levels of phosphorylated amyloid-beta in blood plasma samples of patients diagnosed with Alzheimer’s disease. 相似文献
49.
50.