Genetic aspects of potato resistance to phytophthorosis

Phytophthora infestans Mont. de Bary is the main oomycete pathogen of cultivated crops in the family Solanaceae, especially potato (Solanum tuberosum). Because potato is the fourth most cultivated crop worldwide, its annual losses from late blight are tremendous. Studies of the basic mechanisms of interaction between potato and the late blight pathogen not only expand the fundamental knowledge in this area, but also open up new possibilities for regulating these interactions in order to increase resistance to the pathogen. The interaction of potato and the late blight pathogen can be considered from a genetic point of view, and it is interesting to consider both the response of the potato to the colonization process by P. infestans and the change in gene activity in late blight during plant infection. We can also investigate this process by changing the profile of secondary metabolites of the host and the pathogen. In addition to fundamental work in this area, applied work in the form of the development of new preparations for protecting potatoes is of no less importance. This review briefly describes the main stages of studies of potato resistance to late blight, starting almost from the first works. Much attention is paid to key works on changing the profile of secondary metabolites phytoalexins. A separate section is devoted to the description of both qualitative and quantitative characteristics of potato resistance to the late blight pathogen: their contribution to overall resistance, gene mapping, and regulation capabilities. Both types of traits are important for potato breeding: quantitative resistance due to R-genes is quickly overcome by the pathogen, while quantitative trait loci make it possible to create varieties with almost absolute resistance due to the pyramid of effective genes. The latest approaches in molecular biology make it possible to study translatomic profiles, which makes it possible to look at the interaction of potatoes and the late blight pathogen at a different angle. It has been shown that the process of potato colonization affects not only the activity of various genes and the profile of secondary metabolites: proteins­markers of the response to infection from potatoes have also been identified: they are pathogen-bound proteins and plastid carbonic anhydrase. On the part of P. infestans, fungal cellulose synthase proteins and haustorium-specific membrane protein were markers of infection. Thus, the review contains information on the most relevant complex studies of the genetic mechanisms of potato resistance to late blight

Application features of the electrostatic systems for measuring the secondary electron emission yield

The analysis of the experimental systems for research of secondary electron emission during the interaction of electron beams with matter is presented. The three most common and methodologically developed variants of exper-imental systems are considered. According to their design features and methodological capabilities, they allow for the study of the main parameters of secondary emission depending on the primary electron beam energy and the sample thickness. The evolution of the experimental measuring systems and their improvement from simple to three-electrode systems with pass-through collectors is considered too. The peculiarities of registration of the sec-ondary electrons current emitted from the studied target surface depending on the structural features of the target device are considered too. Application results of the developed three-electrode measuring system for research thin foil emission characteristics have been discussed.Проведено аналіз експериментальних систем дослідження вторинної електронної емісії при взаємодії електронних пучків з речовиною. Розглянуто три найбільш поширені та методологічно розроблені варіанти експериментальних систем. За своїми конструктивними особливостями та методичними можливостями вони дозволяють досліджувати основні параметри вторинної емісії залежно від енергії первинного електронного пучка та товщини зразка. Розглянуто еволюцію експериментальних вимірювальних систем та їх удосконалення від простих до триелектродних систем з прохідними колекторами. Розглянуто також особливості реєстрації струму вторинних електронів у залежності від конструктивних особливостей пристрою мішені. Обговорено результати застосування розробленої триелектродної вимірювальної системи для дослідження емісійних характеристик вторинних електронів з тонкої плівки

Ribosomal profiling as a tool for studying translation in plants: main results, problems and future prospects

The expression of eukaryotic genes can be regulated at several stages, including the translation of mRNA. It is known that the structure of mRNA can affect both the efficiency of interaction with the translation apparatus in general and the choice of translation initiation sites. To study the translated fraction of the transcriptome, experimental methods of analysis were developed, the most informative of which is ribosomal profiling (RP, Ribo-seq). Originally developed for use in yeast systems, this method has been adapted for research in translation mechanisms in many plant species. This technology includes the isolation of the polysomal fraction and high-performance sequencing of a pool of mRNA fragments associated with ribosomes. Comparing the results of transcript coverage with reads obtained using the ribosome profiling with the transcriptional efficiency of genes allows the translation efficiency to be evaluated for each transcript. The exact positions of ribosomes determined on mRNA sequences allow determining the translation of open reading frames and switching between the translation of several reading frames – a phenomenon in which two or more overlapping frames are read from one mRNA and different proteins are synthesized. The advantage of this method is that it provides quantitative estimates of ribosome coverage of mRNA and can detect relatively rare translation events. Using this technology, it was possible to identify and classify plant genes by the type of regulation of their expression at the transcription, translation, or both levels. Features of the mRNA structure that affect translation levels have been revealed: the formation of G2 quadruplexes and the presence of specific motifs in the 5’-UTR region, GC content, the presence of alternative translation starts, and the influence of uORFs on the translation of downstream mORFs. In this review, we briefly reviewed the RP methodology and the prospects for its application to study the structural and functional organization and regulation of plant gene expression

ОПРЕДЕЛЕНИЕ ФЕНОЛЬНЫХ СОЕДИНЕНИЙ В ДЕЗИНФЕКЦИОННЫХ СРЕДСТВАХ

The aspects of analytical determination of disinfectants derivatives of the phenol series аrе considered. The possibility of codetermination of five derivatives of this series in different disinfectants using the RP-HPLC method in the isocratic mode (UV detection) is shown. Alternatively, the possibilities of the determination with the use of spectrophotometry and GC methods are considered. This study and previous ones showed that the extraction of phenol derivatives by organic solvents from а wide range of disinfectants is feasible only in some cases, preferably with the use of hexane as an extractant. Further spectrophotometry of hexane extracts does not always enable to correctly compensate for the effect of background impurities and requires an additional separation of the components. The literature data and experimental results suggest that it is more efficient to analyze the whole series of disinfectants in isopropanol (sometimes in water) by chromatographic methods, preferably by HPLC. Sample preparation reduces to the solubilization of batches of ready-made disinfectants in isopropanol/water. It is optimal to carry out the chromatographic study using elution with acetonitrile-based systems (for example, СН3СN:Н2O, 60:40) providing the correct determination (λ = 280 nт) of phenol derivatives. The completeness of extraction (if the extraction method is used), as well as the metrology aspects of all the analytical determination is set directly in а laboratory during the realization of procedures of introduction/validation according to the internal documents of the system quality management for the relevant structural unit.Рассмотрены аспекты аналитического определения дезинфектантов производных ряда фенола. Показана возможность совместного определения пяти производных данного ряда в различных дезинфицирующих средствах с использованием ОФ ВЭЖХ в изократическом режиме (УФ-детектирование). Альтернативно рассмотрены возможности определения с использованием методов спектрофотометрии и ГЖХ. Настоящее и предшествующие исследования показали, что экстракционное извлечение производных группы фенола органическими растворителями из широкого спектра дезинфицирующих средств доступно только в некоторых случаях, преимущественно при использованием гексана в качестве экстрагента. В дальнейшем спектрофотометрирование гексановых экстрактов не всегда позволяет корректно скомпенсировать влияние фоновых примесей и требует дополнительного разделения компонентов. Исходя из литературных данных и результатов экспериментов, стоит отметить, что производительнее осуществлять анализ всей линейки дезинфекционных препаратов в изопропаноле (иногда в воде) хроматографическими методами, отдавая предпочтение ВЭЖХ. При этом пробоподготовка сводится к солюбилизации навесок готовых средств в изопропаноле/воде. Хроматографическое исследование оптимально проводить с применением в качестве элюента систем на основе ацетонитрила, обеспечивающих корректное определение (λ = 280 нм) производных фенола

Possible background reductions in double beta decay experiments

The background induced by radioactive impurities of $^{208}\rm Tl$ and $^{214}\rm Bi$ in the source of the double beta experiment NEMO-3 has been investigated. New methods of data analysis which decrease the background from the above mentioned contamination are identified. The techniques can also be applied to other double beta decay experiments capable of measuring independently the energies of the two electrons.Comment: 15 pages, 13 figures, accepted in the Nuclear Instruments and Methods

Study of 2 beta-decay of Mo-100 and Se-82 using the NEMO3 detector

After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of Mo-100 (T-1/2 > 3.1 x 10(23) y, 90% CL) and Se-82 (T-1/2 > 1.4 x 10(23) y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: 1.4 x 10(22) y (90% CL) for Mo-100 and T-1/2 > 1.2 x 10(22) y (90% CL) for Se-82. Corresponding bounds on the Majoron-neutrino coupling constant are < (0.5-0.9) x 10(- 4) and <(0.7-1.6) x 10(- 4). Two-neutrino 2beta-decay half-lives have been measured with a high accuracy, (T1/2Mo)-Mo-100 = [7.68 +/- 0.02(stat) +/- 0.54(syst)] x 10(18) y and (T1/2Se)-Se-82 = [10.3 +/- 0.3(stat) +/- 0.7(syst)] x 10(19) y. (C) 2004 MAIK "Nauka/Interperiodica"

Time delays in PG1115+080: new estimates

We report new estimates of the time delays in the quadruple gravitationally lensed quasar PG1115+080, obtained from the monitoring data in filter R with the 1.5-m telescope at the Maidanak Mountain (Uzbekistan, Central Asia) in 2004-2006. The time delays are 16.4 days between images C and B, and 12 days between C and A1+A2, with image C being leading for both pairs. The only known estimates of the time delays in PG1115 are those based on observations by Schechter et al. (1997) -- 23.7 and 9.4 days between images C and B, C and A1+A2, respectively, as calculated by Schechter et al., and 25 and 13.3 days as revised by Barkana (1997) for the same image components with the use of another method. The new values of time delays in PG 1115+080 may be expected to provide larger estimates of the Hubble constant thus decreasing a diversity between the H_0 estimates taken from gravitationally lensed quasars and with other methods.Comment: 5 pages, 2 figures, Accepted for publication in MNRAS Letter