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11.
Mariya M. Mikhailova Andrey A. Panteleyev Mikhail A. Paltsev Andrey A. Panteleyev 《Cell biology international》2019,43(10):1193-1200
It is a well‐known fact, that there is a close interconnection between vascular and neural structures in both embryonic development and postnatal life. Different models have been employed to dissect the mechanisms of these interactions, ranging from in vitro systems (e.g., co‐culture of neural and endothelial cells) to in vivo imaging of central neural system recovery in laboratory animals after artificially induced trauma. Nevertheless, most of these models have serious limitations. Here, we describe an ex vivo model, representing an organotypic co‐culture of aortic fragments (AF) with longitudinal slices of mouse neonatal spinal cord (SC) or dorsal root ganglia (DRG). The samples were co‐cultured in a medium adapted for SC tissue and lacking any pro‐angiogenic or neurotrophic growth factors. It was found, that cultivation of AFs in the SC injury zone (transversal dissection of a SC slice) resulted in the initiation of active aortic sprouting. Remarkably, the endothelial cells exiting the AFs never invaded the SC tissue, concentrating in a nearby area (negative taxis). In contrast, the DRGs, while also promoting the sprouting, were a target of active endothelial CD31+ cell invasion (positive taxis). Thus, the tissues of both central and peripheral nervous systems have a prominent positive effect on aortic sprouting, while the vector of endothelial cell expansion is strictly nervous‐tissue‐type dependent. The ex vivo AF co‐culture with SC or DRG appeared to be a useful and promising model for a further endeavor into the mechanisms driving the complex interactions between neural and endothelial tissues. 相似文献
12.
Dedova IV Nikolaeva OP Mikhailova VV dos Remedios CG Levitsky DI 《Biophysical chemistry》2004,110(1-2):119-128
Differential scanning calorimetry was used to examine the effects of cofilin on the thermal unfolding of actin. Stoichiometric binding increases the thermal stability of both G- and F-actin but at sub-saturating concentrations cofilin destabilizes F-actin. At actin:cofilin molar ratios of 1.5-6 the peaks corresponding to stabilized (66-67 degrees C) and destabilized (56-57 degrees C) F-actin are observed simultaneously in the same thermogram. Destabilizing effects of sub-saturating cofilin are highly cooperative and are observed at actin:cofilin molar ratios as low as 100:1. These effects are abolished by the addition of phalloidin or aluminum fluoride. Conversely, at saturating concentrations, cofilin prevents the stabilizing effects of phalloidin and aluminum fluoride on the F-actin thermal unfolding. These results suggest that cofilin stabilizes those actin subunits to which it directly binds, but destabilizes F-actin with a high cooperativity in neighboring cofilin-free regions. 相似文献
13.
Semashko T. V. Mikhailova R. V. Eremin A. N. 《Applied Biochemistry and Microbiology》2003,39(4):368-374
A method for isolating extracellular glucose oxidase from the fungus Penicillium funiculosum 46.1 using ultrafiltration membranes was developed. Two samples of the enzyme with a specific activity of 914–956 IU were obtained. The enzyme exhibited a high catalytic activity at pH above 6.0. The effective rate constant of glucose oxidase inactivation at pH 2.6 and 16°C was 2.74 × 10–6 s–1. This constant decreased significantly as the pH of the medium increased (4.0–10.0). The temperature optimum for glucose oxidase–catalyzed -D-glucose oxidation was in the range 30–65°C. At temperatures below 30°C, the activation energy for -D-glucose oxidation was 6.42 kcal/mol; at higher temperatures, this parameter was equal to 0.61 kcal/mol. Kinetic parameters of glucose oxidase–catalyzed -D-glucose oxidation depended on the initial concentration of the enzyme in the solution. Glucose oxidase also catalyzed the oxidation of 2-deoxy-D-glucose, maltose, and galactose. 相似文献
14.
The Na,K-ATPase undergoes conformational transitions during its catalytic cycle that mediate energy transduction between the phosphorylation and cation-binding sites. Structure-function studies have shown that transmembrane segments H5 and H6 in the alpha subunit of the enzyme participate in cation binding and transport. The Ca-ATPase crystal structure indicates that the H5 helix extends into the cytoplasmic ATP binding domain, finishing 4-5 A from the phosphorylation site. Here, we test whether the phosphorylation of the Na,K-ATPase leads to conformational changes in the cation-binding H5-H6 hairpin. Using as background an enzyme where all wild-type Cys in the transmembrane region were replaced, Cys were introduced in the joining loop and extracellular ends of H5 and H6. Mutated proteins were expressed in COS cells and probed with Hg(2+), [2-(trimethylammonium)ethyl]methanethiosulfonate (MTSET), and biotin-maleimide, applied to the extracellular media while placing the cells in two different media (K-medium and Na-medium). We assumed that under these treatment conditions most of the enzyme would be in one of two predominant conformations: E1 (K-medium) and E2P (Na-medium). The extent of enzyme inactivation by Hg(2+) or MTSET treatment was dependent on the targeted position; i.e., proteins carrying Cys in the outermost positions were more affected by treatment. Moreover, in the case of proteins carrying Cys at positions 785, 787, and 797, driving the enzyme to phosphorylated conformations (Na-media) led to a larger inactivation. Similarly, biotinylation of introduced Cys was also influenced by the enzyme conformation, with a larger extent of modification after treatment of cells in the Na-medium (E2P form). These results can be explained by the enzyme phosphorylation driving the outward movement of the H5 helix. Thus, they provide experimental evidence for a structure-function mechanism where, via H5, enzyme phosphorylation leads to a conformational change at the cation-binding site and the consequent cation translocation. 相似文献
15.
R. V. Mikhailova T. V. Semashko A. G. Lobanok 《Applied Biochemistry and Microbiology》2002,38(3):236-239
Metabolic inhibitors, riboflavin, and end products of glucose oxidation were shown to be effective for the selection ofPenicillium funiculosum mutant strains with a high glucose oxidase activity. The incidence of positive mutations was highest in clones resistant to sodium azide, riboflavin, and -D-glucono--lactone. Enzyme activity in Penicillium funiculosum mutants was studied in submerged culture. The level of glucose oxidase synthesis in seven cultures was 24–56% higher than that in the parent strain of Penicillium funiculosum NMM95.132. 相似文献
16.
Elena I. Mikhailova Tomás Naranjo Ken Shepherd Jannie Wennekes-van Eden Christa Heyting J. Hans de Jong 《Chromosoma》1998,107(5):339-350
The Ph1 locus in wheat influences homo(eo)logous chromosome pairing. We have analysed its effect on the behaviour and morphology
of two 5RL rye telosomes in a wheat background, by genomic in situ hybridisation (GISH), using rye genomic DNA as a probe.
Our main objective was to study the effect of different alleles of the Ph1 locus on the morphology and behaviour of the rye telosomes in interphase nuclei of tapetal cells and in pollen mother cells
at early stages of meiosis. The telosomes, easily detectable at all stages, showed a brightly fluorescing chromomere in the
distal region and a constriction in the proximal part. These diagnostic markers enabled us to define the centromere and telomere
regions of the rye telosomes. In the presence of functional copies of Ph1, the rye telosomes associated at pre-leptotene, disjoined and reorganised their shape at leptotene, and became fully homologously
paired at zygotene – pachytene. In plants without functional alleles (ph1bph1b), the rye telosomes displayed an aberrant morphology, their premeiotic associations were clearly disturbed and their pairing
during zygotene and pachytene was reduced and irregular. The Ph1 locus also influenced the behaviour of rye telosomes in the interphase nuclei of tapetal cells: in Ph1Ph1 plants, the rye telosomes occupied distinct, parallel-oriented domains, whereas in tapetal nuclei of ph1bph1b plants they were intermingled with wheat chromosomes and showed a heavily distorted morphology. The results shed new light
on the effect of Ph1, and suggest that this locus is involved in chromosome condensation and/or scaffold organisation. Our explanation might account
for various apparently contradictory and pleiotropic effects of this locus on both premeiotic associations of homologues,
the regulation of meiotic homo(eo)logous chromosome pairing and synapsis, the resolution of bivalent interlockings and centromere
behaviour.
Received: 27 April 1998; in revised form: 5 August 1998 / Accepted: 11 August 1998 相似文献
17.
The Peterhof Collection of spontaneous meiotic mutants of rye was used as a model to study the genetic control of meiosis
key events in an organism with a large genome. A combination of methods, which included fluorescence in situ DNA-DNA hybridization,
sequencing of recombinogenic proteins, and immunocytochemical analysis of meiosis proteins, clearly showed that mutation sy1 affects recombination events, asynapsis in mutant sy9 is connected with defects of the assembly of synaptonemal complex axial cores, and that synapsis defects in mutant sy10 are coupled with the presence of protein Zyp1 in the core region. The assembly of proteins Asy1 and Zyp1 on the axes of meiotic
chromosomes was shown to occur separately, which is a specific feature of rye, as compared to arabidopsis. 相似文献
18.
Makarova AM Gorbacheva LR Savinkova IV Mikhailova AG Rumsh LD Pinelis VG Strukova SM 《Biochemistry. Biokhimii?a》2010,75(9):1153-1159
The effects of full-size bovine enteropeptidase (BEK) and of human recombinant light chain enteropeptidase (L-HEP) on survival
of cultured hippocampal neurons were studied under conditions of glutamate excitotoxicity. Low concentrations of L-HEP or
BEK (0.1–1 and 0.1–0.5 nM, respectively) protected hippocampal neurons against the death caused by 100 μM glutamate. Using
the PAR1 (proteinase-activated receptor) antagonist SCH 79797, we revealed a PAR1-dependent mechanism of neuroprotective action
of low concentrations of enteropeptidase. The protective effect of full-size enteropeptidase was not observed at the concentrations
of 1 and 10 nM; moreover, 10 nM of BEK caused death of 88.9% of the neurons, which significantly exceeded the cell death caused
by glutamate (31.9%). Under conditions of glutamate cytotoxicity the survival of neurons was 26.8% higher even in the presence
of 10 nM of L-HEP than in the presence of 10 nM BEK. Pretreatment of cells with 10 nM of either form of enteropeptidase abolished
the protective effect of 10 nM thrombin under glutamate cytotoxicity. High concentrations of BEK and L-HEP caused the death
of neurons mainly through necrosis. 相似文献
19.
Arina L. Maltseva Marina A. Varfolomeeva Roman V. Ayanka Elizaveta R. Gafarova Egor A. Repkin Polina A. Pavlova Alexei L. Shavarda Natalia A. Mikhailova Andrei I. Granovitch 《Ecology and evolution》2021,11(16):11134
Divergence of ecological niches in phylogenetically closely related species indicates the importance of ecology in speciation, especially for sympatric species are considered. Such ecological diversification provides an advantage of alleviating interspecies competition and promotes more efficient exploitation of environmental resources, thus being a basis for ecological speciation. We analyzed a group of closely related species from the subgenus Neritrema (genus Littorina, Caenogastropoda) from the gravel‐bouldery shores. In two distant sites at the Barents and Norwegian Sea, we examined the patterns of snail distribution during low tide (quantitative sampling stratified by intertidal level, presence of macrophytes, macrophyte species, and position on them), shell shape and its variability (geometric morphometrics), and metabolic characteristics (metabolomic profiling). The studied species diversified microbiotopes, which imply an important role of ecological specification in the recent evolution of this group. The only exception to this trend was the species pair L. arcana / L. saxatilis, which is specifically discussed. The ecological divergence was accompanied by differences in shell shape and metabolomic characteristics. Significant differences were found between L. obtusata versus L. fabalis and L. saxatilis / L. arcana versus L. compressa both in shell morphology and in metabolomes. L. saxatilis demonstrated a clear variability depending on intertidal level which corresponds to a shift in conditions within the occupied microhabitat. Interestingly, the differences between L. arcana (inhabiting the upper intertidal level) and L. compressa (inhabiting the lower one) were analogous to those between the upper and lower fractions of L. saxatilis. No significant level‐dependent changes were found between the upper and lower fractions of L. obtusata, most probably due to habitat amelioration by fucoid macroalgae. All these results are discussed in the contexts of the role of ecology in speciation, ecological niche dynamics and conservatism, and evolutionary history of the Neritrema species. 相似文献
20.
E. A. Volosnikova N. I. Akulova Ya. S. Gogina G. M. Levagina V. K. Mikhailova L. R. Lebedev V. F. Podgornyi Yu. V. Telegina 《Applied Biochemistry and Microbiology》2010,46(9):865-869
Optimization of the stage of fractioning of nucleotide material has been performed, and a technology for purification and
obtaining of plasmid DNAs for pharmaceutical purposes has been developed. Plasmid DNAs can be used for construction of DNA
vaccines to urgent viral infections. Conditions for extraction and preliminary purification of DNA by salt and alcohol precipitations
were determined. An effective gel-filtration procedure of separation of plasmid DNA from contaminants was suggested. 相似文献