Наукові праці професорсько-викладацького складу ЛДУФК в базах даних Scopus, WoS, Tomson Reuters

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Molecular Cloning of the GTP-Cyclohydrolase Structural Gene RIB1 of Pichia guiZZiermondii Involved in Riboflavin Biosynthesis
(1995) Liauta-Teglivets, O.; Hasslacher, M.; Boretsky, Yuriy; Konlwein, S.; Shavlovskii, G.; Борецький, Юрій
The structural gene of GTP-cyclohydrolase, involved in riboflavin biosynthesis, was cloned from a Pichia guilliermondii genomic library. A 1855 bp genomic DNA fragment complementing the riboflavin auxotrophies of an Escherichia coli ribA mutant, defective in GTP-cyclohydrolase 11, and a P. guilliermondii rib1 mutant was isolated and sequenced. An open reading frame with the potential to encode a protein of 344 amino acids with a predicted molecular mass of 38 71 1 Da was detected. The P. guilliermondii enzyme shows a high degree of homology to GTP-cyclohydrolases type I1 from E. coli and Baccillus subtilis and to GTP-cyclohydrolase from Saccharomyces cerevisiue. Functional GTP-cyclohydrolase from P. guilliermondii may consist of four identical subunits. The sequence of the RlBl gene of P. guilliermondii was submitted to the EMBL sequence database and is accessible under Accession Number 249093.
Aspartate aminotransferase from an alkalophilic Bacillus contains an additional 20 - amino acid extension at its fu nctionally i mportant N - terminus
(1996) Battchikova, Natalia; Koivulehto, Marianne; Denesyuk, Alexander; Ptitsyn, Leonid; Boretsky, Yuriy; Hellman, Jukka; Korpela, Timo; Борецький, Юрій
Aspartate aminotransferase (AspAT), responsible for a minor part of the total AspAT enzymic activity in alkalophilic Bacillus circulans, was purified, its N-terminal amino acid sequence was determined, and its gene was cloned as two separate fragments. DNA sequencing showed an open reading frame of 432 amino acids (Mr 47,439) exhibiting moderately low homology with AspATs from other sources. Sequence alignment of the enzyme with chicken mitochondrial, chicken cytoplasmic and Escherichia coli AspATs was performed with the MULTALIN program and further optimized assuming that the three-dimensional structures of the proteins were conserved. The primary structure of the studied AspAT diverged markedly from the others in the catalytically important small domain and in a segment of 31 amino acids in the large domain. The functional N-terminal arm was about two times longer than those of AspATs from other sources. According to the molecular model, the unique regions of B. circulans AspAT are all located together, forming a continuous network of contacts. Additional contacts formed by the elongated N-terminal arm may result in some limitation of domain movements in the alkalophilic enzyme in comparison to in other known AspATs.
Identification of an ARS element and development of a high efficiency transformation system for Pichia guilliermondii
(1999) Boretsky, Yuriy; Voronovsky, Andriy; Liuta-Tehlivets, Oksana; Hasslacher, Meinhard; Kohlwein, Sepp D.; Shavlovsky, Georgiy M.; Борецький, Юрій
An Autonomously Replicating Sequence ele- ment adjacent to the RIB1 gene encoding GTP cyclohydrolase II of the yeast Pichia guilliermondii was identi®ed by transformation experiments. Detailed se- quence analysis unveiled two potential ARS elements located 5¢ and 3¢ of the RIB1 open reading frame. The chromosomal fragment containing the ARS-like se- quence 3¢ to the RIB1 structural gene, called PgARS, conferred high transformation frequencies of 104±105 transformants/lg of DNA to a pUC19-derived plasmid in P. guilliermondii. The PgARS element also conferred autonomous replication to hybrid plasmids in this host. Based on this element a series of Escherichia coli shuttle vectors for e cient transformation of the ¯avinogenic yeast P. guilliermondii was developed.
Mechanism for conversion of the conductivity type in arsenic doped p-CdxHg1–xTe subject to ionic etching
(2001) Bogoboyashchiy, V.; Vlasov, Andrii; Izhnin, I.
Based on an analysis of chemical diffusion of mercury in p-CdxHg1–xTe:As narrow-band solid solutions, a mechanism for conversion of the conductivity type upon ionic etching is suggested. It is shown that the n–p conversion of the conductivity in this case is due to the formation of a donor complex between arsenic in the Te sublattice and an interstitial Hg atom. Moreover, the electron concentration in the converted layer corresponds to the concentration of the implanted arsenic impurity. The theoretical results are confirmed by the experimental investigation of the electron concentration distribution over the n-layer of a p-CdxHg1–xTe:As epistructure converted upon ionic etching.
Controlled arsenic diffusion in epitaxial CdXHg1-XTe layers in the evaporation-condensation-diffusion process
(2002) Vlasov, Andriy; Pysarevsky, V.; Storchun, O.; Shorchenko, A.; Bonchyk, A.; Pokhmurska, H.; Barcz, A.; Swiatek, Z.; Власов, Андрій; Писаревський, В.; Сторчун, О.; Шорченко, А.; Бончик, А.; Похмурська, Г.; Святек, З.
The results of controlled doping of CdxHg1yxTe epitaxial layers are presented. The investigated layers were obtained by the evaporation–condensation–diffusion method in the process of isothermal growth. The process of auto diffusion from the solid phase was investigated. This process consists in the diffusion of As dopants from CdTe substrate into the grown epitaxial layer. Two types of CdTe substrates, uniformly doped in the process of synthesis and unalloyed with ion implanted surface layer, have been used as sources of As diffusant. Comparative analysis of galvanomagnetic measurements and SIMS spectra was carried out. The results of investigations indicate the very high, almost 100%, electrical activity of As dopants in the CdxHg1yxTe epitaxial grown layer. 2002 Elsevier Science B.V. All rights reserved.
Restoration of the Wild-Type Phenotype in Pichia guilliermondii Transformants
(2002) Pinyaga, Yu.; Prokopiv, T.; Petrishin, A.; Khalimonchuk, O.; Protchenko, O.; Fedorovich, D.; Boretsky, Yuriy; Борецький, Юрій
Pichia guilliermondii strain with blocked GTP cyclohydrolase II was transformed using replicative plasmids and their fragments containing the structural gene RIB1 of this enzyme. Experiments showed that the presence of the ARS element and the promoter region of this gene in the genome of transformants reduces the probability of their reversion to the wild-type phenotype. Different types of recombination in the yeast P. guilliermondii are discussed.
Defect Structure Rebuilding by Ion Beam Milling of As and Sb Doped p-Hg1–xCdxTe
(2002) Berchenko, N.; Bogoboyashchiy, V.; Izhnin, I.; Vlasov, Andriy; Берченко, Н.; Богобоящий, В.; Іжнін, І.; Власов, Андрій
This study focuses on developing an understanding of the mechanisms of ion beam milling induced p-to-n conversion in extrinsically (As or Sb) doped p-Hg1––xCdxTe with x 0.2. The basis of modeling is the quasichemical approach and the model of superfast Hg interstitial atoms diffusion that has permitted to explain the similar conversion occurred in Hg vacancy-doped p-type Hg1––xCdxTe. In an acceptor doped material a donor is generated due to the formation of a complex (of interstitial Hg atom and an As or Sb atom located in the Te site). This model provides reasonably good fits with the experimental results obtained for As and Sb doped Hg1––xCdxTe epitaxial layers where the electron concentration in the converted n-layer corresponds to the concentration of the p-type dopants. Different efficiency of the conductivity conversion observed for As and Sb doped samples may be explained by different enthalpy of complex formation calculated for AsTe–HgI and SbTe– HgI pairs.
The response to iron deprivation in Saccharomyces cerevisiae : expression of siderophore - based systems of iron uptake
(2002) Philpott, C.; Protchenko, О.; Kim, Y .; Boretsky, Yuriy; Shakoury - Elizeh, M.; Борецький, Юрій
The budding yeast Saccharomyces cerevisiae responds to growth in limiting amounts of iron by activating the transcription factor Aftlp and expressing a set of genes that ameliorate the effects of iron deprivation. Analysis of iron-regulated gene expression using cDNA microarrays has revealed the set of genes controlled by iron and Aftlp. Many of these genes are involved in the uptake of siderophore-bound iron from the environment. One family of genes, FIT1, FIT2 and FIT3, codes for mannoproteins that are incorporated into the cell wall via glycosylphosphatidylinositol anchors. These genes are involved in the retention of siderophore-iron in the cell wall. Siderophorebound iron can be taken up into the cell via two genetically separable systems. One system requires the reduction and release of the iron from the siderophore prior to uptake by members of the Fre family of plasma-membrane metalloreductases. Following reduction and release from the siderophore, the iron is then taken up via the high-affinity ferrous transport system. A set of transporters that specifically recognizes siderophore- iron chelates is also expressed under conditions of iron deprivation. These transporters, encoded by ARNI, ARN2/ TAFl, ARN3/SIT1 and ARN4IENB1, facilitate the uptake of both hydroxamate- and catecholate-type siderophores. The Arn transporters are expressed in intracellular vesicles that correspond to the endosomal compartment, which suggests that intracellular trafficking of the siderophore and/or its transporter may be important for uptake.
Conductivity type conversion in p- CdXHg1-XTe
(2003) Berchenko, N.; Bogoboyashchiy, V.; Izhnin, I.; Vlasov, Andriy; Kurbanov, K.; Yudenkov, V.; Берченко, Н.; Богобоящий, В.; Іжнін, І.; Власов, Андрій; Курбанов, К.; Юденков, В.
Investigations and comparative analysis of p-to-n type conductivity conversion processes on the identical samples of vacancy doped p-CdxHg–xTe (x 0.2) under ion-beam milling (IBM) and anodic oxide annealing and on the identical samples of As-doped p-CdxHg1–xTe (x 0.22) under IBM and anodic oxide annealing have been carried out. The conductivity type conversion has been observed at the considerable depth of the vacancy doped material both under IBM or under anodic oxide annealing while in the case with As-doped material only under IBM. It was considered that conversion in all these processes was determined by the mercury interstitial diffusion from corresponding mercury diffusion source and recombination with its native acceptors – cationic vacancies (in the first case) or with donor complex formations (in the second one). It has been shown that in the vacancy-doped p-CdxHg1–xTe the effective diffusion coefficients for the mercury interstitials that determines the depth of the converted layer are equal each other at equal temperatures either under thermal annealing in the saturated mercury vapour or anodic oxide annealing. It proves the identity of the mercury concentration in the diffusion source. Absence of the conversion under anodic oxide annealing in the As-doped p-CdxHg1–xTe is explained by insufficient Hg concentration in the source and it matches well with necessary condition for donor complex formation as it takes place under IBM.
Time Relaxation of Point Defects in p- and n-(HgCd)Te after Ion Milling
(2003) Belas, E.; Bogoboyashchyy, V.; Grill, R.; Izhnin, I.; Vlasov, Andriy; Yudenkov, V.; Белас, Е.; Богобоящий, В.; Гріл, Р.; Іжнін, І.; Власов, Андрій; Юденков, В.
RH(77 K) of the n-type layer created by ion milling is investigated in Hg vacancy-doped, As-doped, and In-predoped p-type, and In-doped n-type Hg1−xCdxTe (0.2 < x < 0.22) samples. We show that the n-type layer is formed, and the temperature-activated relaxation occurs in all cases. The annealing at 75°C results in a gradual degradation of the converted n-type layer and a back n-to-p conversion within 8 days. The existence of a high-conducting, surfacedamaged region with a high-electron density (∼1018 cm−3) and a low mobility (∼103 cm2/Vs) is confirmed, and its influence on the relaxation is studied.
High temperature arsenic doping of CdHgTe epitaxial layers
(2004) Vlasov, Andriy; Bogoboyashchiy, V.; Bonchyk, O.; Barcz, A.; Власов, Андрій; Богобоящий, В.; Бончик, О.
Experimental results on solid-state arsenic doping of the n-type bulk and ISOVPE epitaxial CdXHg1-XTe (X = 0.19÷0.3) alloys are presented. The arsenic doped thin epitaxial CdxHg1-xTe films (nAs ≈ 5⋅1016÷1⋅1020 cm-3; d =2÷5 μm) obtained by RF sputtering in a mercury glow discharge were used as As diffusion sources. The arsenic diffusion and activation were carried out at temperatures Т = 500÷600°С under Hg vapour pressure. Immediately after the high temperature treatment all samples were annealed to annihilate point defects. The SIMS analysis was used for determination of the quantitative admixture distribution of As in the diffusion area. The arsenic electrical activity has been evaluated by means of differential Hall, resistivity and thermoemf measurements. The analysis of experimental data obtained as well as their comparison with previously obtained results has been performed.
Positive selection of mutants defective in transcriptional repression of riboflavin synthesis by iron in the flavinogenic yeast Pichia guilliermondii
(2005) Boretsky, Yuriy; Kapustyak, Kostyantyn; Fayura, Lyubov; Stasyk, Oleh; Stenchuk, Mykola; Bobak, Yaroslav; Drobot, Lyudmyla; Sibirny, Andriy; Борецький, Юрій
It is known for many years that iron represses synthesis of riboflavin (RF) and most of RF-synthesizing enzymes in several yeast species, known as flavinogenic yeasts. However, the mechanism of such repression is not known. We have found that iron represses transcription of RIB1 and RIB7 genes coding for the first and the last enzymes of RF biosynthesis in the model flavinogenic organism Pichia guilliermondii. To decipher molecular mechanisms of iron-dependent repression, isolation and study of the regulatory mutants defective in corresponding regulation is desirable. However, no suitable methods for isolation of such mutants were previously available. We have produced a single-point transition mutation in the RIB1 gene. The corresponding rib1-86 mutant exhibits leaky phenotype and is unable to grow in iron-sufficient minimal medium without exogenous RF. However, it can grow in minimal iron-deficient medium without RF, or in iron-sufficient medium upon introduction of the previously-isolated regulatory mutation rib81, which leads to increase in RF production. Using the rib1-86 mutant as parental strain, a collection of mutants able to grow in iron-sufficient medium without exogenous RF has been isolated. The mutants appeared to be defective in regulation of RF biosynthesis and iron homeostasis and were divided into six new complementation groups. Study of one corresponding mutant, red6, showed derepression of RIB1 mRNA synthesis in iron-sufficient medium.
Relaxation of electrical properties of n-type layers formed by ion milling in epitaxial HgCdTe doped with V-group acceptors
(2006) Bogoboyashchyy, V.; Izhnin, I.; Mynbaev, K.; Pociask, M.; Vlasov, Andriy
The relaxation of electrical properties of As- and Sb-doped HgCdTe epitaxial layers, which were converted into n-type by ion milling, is studied. It is shown that donor complexes formed under ion milling and responsible for p-to-n conductivity type conversion are not stable, and their concentration decreases upon storage even at room temperature. Increasing the temperature of the storage speeds up the relaxation process. It is demonstrated that the relaxation is caused by the disintegration of the donor complexes that starts right after the end of the milling process because of the decrease in the concentration of interstitial mercury atoms, which were generated during the milling. The results presented in the paper are important for the development of the technology of photodetectors based on HgCdTe doped with V-group acceptors.
Developmental trends in sports for the disabled. The case of Summer Paralympics
(2006) Prystupa, Evhen; Prystupa, Tetiana; Bolach, Eugeniusz; Приступа, Євген; Приступа, Тетяна; Болах, Євген
The paper presents the most important trends in spport for the disabled in the period between the 1 and the 12 Paralympic Games.
Archer–bow–arrow behaviour in the vertical plane
(2006) Zanevskyy, Ihor; Заневський, Ігор
Theoretical and experimental results of research on the problem of archer, bow and arrow behaviour in the vertical plane are presented. The aim of the research is to develop a method of computer simulation of static and dynamic interactions between the archer, bow and arrow system in order to provide archery with practical recommendations. A model of an archer’s body is presented as a mechanical system composed of a few solid bodies, which are connected to each other and to the ground with viscoelastic elements. Mechanical and mathematical model of bow and arrow geometry in vertical plane in braced and drawn situations is investigated. An asymmetrical scheme, rigid beams, concentrated elastic elements and elastic string are the main features of the model. Numerical results of computer simulation of archer, bow and arrow interactions are presented in graphical form, which makes the methods easy to use by sportsmen and coaches.
Development of a transformation system for gene knock - out in the flavinogenic yeast Pichia guilliermondii
(2007) Boretsky, Yuriy; Pynyaha, Yuriy; Boretsky, Volodymyr; Kutsyaba, Vasyl; Protchenko, Olga; Philpott, Caroline; Sibirny, Andriy; Борецький, Юрій
Pichia guilliermondii is a representative of a yeast species, all of which over-synthesize riboflavin in response to iron deprivation. Molecular genetic studies in this yeast species have been hampered by a lack of strain-specific tools for gene manipulation. Stable P. guilliermondii ura3 mutants were selected on the basis of 5′-fluoroorotic acid resistance. Plasmid carrying Saccharomyces cerevisiae URA3 gene transformed the mutant strains to prototrophy with a low efficiency. Substitution of a single leucine codon CUG by another leucine codon CUC in the URA3 gene increased the efficiency of transformation 100 fold. Deletion cassettes for the RIB1 and RIB7 genes, coding for GTP cyclohydrolase and riboflavin synthase, respectively, were constructed using the modified URA3 gene and subsequently introduced into a P. guilliermondii ura3 strain. Site-specific integrants were identified by selection for the Rib− Ura+ phenotype and confirmed by PCR analysis. Transformation of the P. guilliermondii ura3 strain was performed using electroporation, spheroplasting or lithium acetate treatment. Only the lithium acetate transformation procedure provided selection of uracil prototrophic, riboflavin deficient recombinant strains. Depending on the type of cassette, efficiency of site-specific integration was 0.1% and 3–12% in the case of the RIB1 and RIB7 genes, respectively. We suggest that the presence of the ARS element adjacent to the 3′ end of the RIB1 gene significantly reduced the frequency of homologous recombination. Efficient gene deletion in P. guilliermondii can be achieved using the modified URA3 gene of S. cerevisiae flanked by 0.8–0.9 kb sequences homologous to the target gene.
Influence of laser shock waves on As implanted HgCdTe
(2007) Yakovyna, V.; Berchenko, N.; Kuzma, M.; Vlasov, Andriy; Яковина, В.; Берченко, Н.; Кузма, М.; Власов, Андрій
The principal purpose of our research is to show that low-temperature treatment of materials can be successfully used instead of annealing. Laser shock waves (LSW) were chosen as an alternative to form p-n junctions in HgCdTe after arsenic ions were implanted. Electrical characteristics of As implanted HgCdTe bulk crystals were studied to determine the effect of LSW generated by nanosecond laser irradiation pulses. The samples were of n-type conductivity immediately after the implantation. Then LSW processing was performed under increasingly growing laser beam power density and shock wave pressure. The experiment demonstrated that a threshold shock wave pressure should be reached to ensure the p-to-n conductivity conversion in the surface layer of samples. On the whole the results provide evidence that LSW combined with ion implantation can be used to form p-n junctions in HgCdTe
Mutations and environmental factors affecting regulation of riboflavin synthesis and iron assimilation also cause oxidative stress in the yeast Pichia guilliermondii
(2007) Boretsky, Yuriy; Protchenko, Olga; Prokopiv, Tetiana; Mukalov, Igor; Fedorovych, Daria; Sibirny, Andriy
Iron deficiency causes oversynthesis of riboflavin in several yeast species, known as flavinogenic yeasts. However, the mechanisms of such regulation are not known. We found that mutations causing riboflavin overproduction and iron hyperaccumulation (rib80, rib81 and hit1), as well as cobalt excess or iron deficiency all provoke oxidative stress in the Pichia guilliermondii yeast. Iron content in the cells, production both of riboflavin and malondialdehyde by P. guilliermondii wild type and hit1 mutant strains depend on a type of carbon source used in cultivation media. The data suggest that the regulation of riboflavin biosynthesis and iron assimilation in P. guilliermondii are linked with cellular oxidative state.
Biological Regeneration as a Factor for Muscle Strength Optimization in Upper Limbs of Disabled Weight lifters with Cerebral Palsy
(2007) Prystupa, Tetyana; Prystupa, Eugeniusz; Wołyńska‐Ślężyńska, Alicja; Ślężyński, Jan; Приступа, Тетяна; Приступа, Євген; Волинська-Сленжинська, Аліція; Сленжинський, Ян
Currently the sport of disabled goes through a particular renaissance. It is not only a universal method for an effective rehabilitation, but also a stimulant for physical and motor development for disabled, especially those with infantile cerebral palsy. Due to a constant increase of training loads in disabled sport, the role of physical exertion efficiency in regeneration is very important. The rational usage of biological regeneration is an important factor for increasing the functional abilities and an inseparable part of training exercises. Зараз спорт для інвалідів переживає особливий ренесанс. Це є не тільки універсальним методом ефективної реабілітації, а й a стимулятор фізичного та рухового розвитку інвалідів, особливо хворі на дитячий церебральний параліч. За рахунок постійного підвищення рівня підготовки навантажень в інвалідному спорті дуже важлива роль ефективності фізичних навантажень у регенерації. Раціональне використання біологічної регенерації є важливий фактор підвищення функціональних можливостей і невід'ємна частина тренувальних вправ.
The Pleiotropic Nature of rib80, hit1 , and red6 Mutations Affecting Riboflavin Biosynthesis in the Yeast Pichia guilliermondii
(2007) Fayura, Lyubov; Fedorovych, Daria; Prokopiv, Tetiana; Boretsky, Yuriy; Sibirny, Andriy
The yeast Pichia guilliermondii is capable of riboflavin overproduction under iron deficiency. The rib80, hit1 , and red6 mutants of this species, which exhibit impaired riboflavin regulation, are also distinguished by increased iron concentrations in the cells and mitochondria, morphological changes in the mitochondria, as well as decreased growth rates (except for red6 ) and respiratory activity. With sufficient iron supply, the rib80 and red6 mutations cause a 1.5–1.8-fold decrease in the activity of such Fe–S cluster proteins as aconitase and flavocytochrome b2, whereas the hit1 mutation causes a six-fold decrease. Under iron deficiency, the activity of these enzymes was equally low in all of the studied strains.

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