Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to resistance; and strengthen the case for a role in survival of systems involved in manganese and iron homeostasis

Method of Optical Diagnostics of Grain Seeds Infected with Fusarium

Optical sensors have shown good capabilities for detecting and monitoring plant diseases, including fusariosis. The spectral characteristics of the excitation and luminescence of wheat, oat and barley seeds were measured using a diffraction spectrofluorimeter in the range of 180–700 nm. It was found that during infection, the spectral density of the absorption capacity increases and the curve ηe(λ) shifts upwards in the range of 380–450 nm. The shift to the left is also noticeable for the wheat and barley spectra. The photoluminescence flux at λe = 232 nm increased by 1.71 times when oat seeds were infected, by 2.63 times when wheat was infected and by 3.14 times when barley was infected. The dependences of the infection degree on the photoluminescence flux are statistically and reliably approximated by linear regression models with determination coefficients R2 = 0.83–0.95. The method of determining the degree of infection can include both absolute measurements of photoluminescence flux in the range of 290–380 nm and measurements of the flux ratios when excited by radiation of 232 nm and 424 nm for wheat and 485 nm for barley. An optoelectronic device for remote monitoring can be designed in order to implement the methodology for determining the degree of infection of agricultural plant seeds

Photoluminescent Sensor of Scarification Efficiency of Fodder Plants’ Seeds

Optoelectronic sensors open up new possibilities for predicting the yield for their possible correction, including increasing the seed germination of forage plants. The luminescent properties of unscarified and scarified seeds of various germination galega, clover and alfalfa are compared. The dependence of germination on the photoluminescence flux is approximated by linear equations with a determination coefficient R2 = 0.932–0.999. A technological process for analyzing the scarification quality of forage seed plants is proposed, including sample preparation, photoluminescence excitation and registration, amplification of the received electrical signal and determination of germination based on calibration equations. This is followed by a decision on sowing, or re-scarification. The scheme of the scarification quality control device has been developed for which the LED, as well as the radiation receiver and other elements, has been selected according to the energy efficiency criterion. Mechanical scarification of the forage plants’ seed surfaces has a significant effect on their photoluminescent properties. The flux increases by 1.5–1.7 times for galega, 2.0–3.0 times for clover and 2.3–3.9 times for alfalfa. Linear approximation of the flux dependence on germination with a high coefficient of determination allows us to obtain reliable linear calibration equations. Preliminary mock-up laboratory tests allow us to talk about the developed method’s effectiveness and device

58 Agricultural Education and Extension

Ecosystem Health and Sustainable Agricultur

Detection of Fusarium infected seeds of cereal plants by the fluorescence method.

Infection of seeds of cereal plants with fusarium affects their optical luminescent properties. The spectral characteristics of excitation (absorption) in the range of 180-700 nm of healthy and infected seeds of wheat, barley and oats were measured. The greatest difference in the excitation spectra of healthy and infected seeds was observed in the short-wave range of 220-450 nm. At the same time, the excitation characteristics of infected seeds were higher than those of healthy ones, and the integral parameter Η in the entire range was 10-56% higher. A new maximum appeared at the wavelength of 232 nm and the maximum value increased by 362 nm. The spectral characteristics were measured when excited by radiation at wavelengths of 232, 362, 424, 485, 528 nm and the luminescence fluxes were calculated. It is established that the photoluminescence fluxes Φ in the short-wave ranges of 290-380 nm increase by 1.58-3.14 times and 390-550 nm-by 1.44-2.54 times. The fluxes in longer wavelength ranges do not change systematically and less significantly: for wheat, they decrease by 12% and increase by 19%, for barley, they decrease by 10% and increase by 33%. The flux decreases by 43-71% for oats. Based on the results obtained for cereal seeds, it is possible to further develop a method for detecting fusarium infection with absolute measurements of photoluminescence fluxes in the range of 290-380 nm, or when measuring photoluminescence ratios: for wheat seeds when excited with wavelengths of 424 nm and 232 nm (Φ424/Φ232); for barley seeds-when excited with wavelengths of 485 nm and 232 nm (Φ485/Φ232) and for oat seeds-when excited with wavelengths of 424 nm and 362 nm (Φ424/Φ362)

Photoluminescent Control Ripeness of the Seeds of Plants

The development of technology for objectively determining the ripeness of plant seeds is an urgent task of modern agricultural production. An alternative to existing methods is optical photoluminescent technology, which is characterized by high accuracy, selectivity, expressiveness, as well as being remote and non-destructive. The spectral characteristics of excitation and photoluminescence of wheat, oat, and corn seeds during their maturation were measured using a spectrofluorometer using a previously developed technique. It was found that during maturation, the short-wave component of the excitation spectra decreases (λs=362 nm) and the long-wave component increases (λl=485 nm). After measuring the luminescence spectra, the integral photoluminescence fluxes for long-wave and short-wave excitation, as well as their ratio, were determined. We have obtained statistically reliable linear regression models of the dependence of long-wave and short-wave photoluminescence flows on the maturation time. Based on the obtained dependencies, a technology was developed for determining the degree of physiological maturation and making decisions about harvesting ripe seeds. It includes sample preparation, excitation and registration of luminescent radiation, amplification of the received signals and their relations, obtaining information about the degree of ripeness taking into account a priori dependencies

Rol' svobodnoradikal'no oposredovannogo okislitel'nogo stressa v razvitii diabeticheskoy polineyropatii

Цель. Изучение некоторых патогенетических механизмов диабетической полинейропатии, а именно взаимосвязи перекисного окисления липидов, активности ферментативной антиоксидантной защиты и гемореологических нарушений у больных сахарным диабетом (СД), имеющих дистальную диабетическую полинейропатию. Материалы и методы. Обследовано 212 больных СД 1 и 2 типа, осложненным дистальной диабетической полинейропатией (ДДПНП) 1 и 2 стадии. Проводилось исследование процессов перекисного окисления (ПОЛ). Определялись диеновые конъюгаты (ДК) и триеновые конъгаты (ТК). Определяли уровнь общих липидов. Для определения деформируемости эритроцитов (ДЭ) был использован метод ригидометрии. Результаты. У больных СД и ДДПНП даже при наличии субкомпенсации гликемии имеет место повышение активности свободнорадикально-опосредованного окислительного стресса, что выражается в накоплении первичных, промежуточных и конечного продукта ПОЛ ? оснований Шиффа. У больных СД даже при небольшой длительности заболевания имеет место нарушение деформируемости эритроцита (ДЭ), что способствует усилению эндоневральной гипоксии. подтверждено наличие отрицательной взаимосвязи между этими двумя характеристиками метаболических и сосудистых нарушений: уровнем холестерина и деформируемости. Выводы. Наши исследования подтверждают механизмы диабетической полинейропатии: усиление окислительного стресса с накоплением промежуточных и конечных продуктов пероксидации, снижение активности ферментативной антиоксидантной защиты. Препараты, ограничивающие активность свободнорадикально-опосредованного окислительного стресса и активизирующие антиоксидантную защиту, являются средствами патогенетической терапии осложнений сахарного диабета, в том числе и полинейропатии

A Laboratory Investigation of the Probable Mechanisms of the Action of an Artificial Thunderstorm Cell on Model Aircraft Radomes

The results of experimental laboratory investigations of possible mechanisms of the impact of lightning and thunderclouds on aircraft radomes and equipment inside them are presented. An artificial thunderstorm cell of negative polarity and model aircraft radomes with lightning diverter strips have been used. Experiments have shown that the discharge processes in a radome model significantly depend on the magnitude of the charge that accumulates on the inner and outer surfaces of the radome shell. It is established that the accumulation of large-magnitude charges of different signs on the outer and/or inner surface of the radome (up to hundreds of µC/m2) shell leads to a multivariance of the mechanisms of development of discharge processes inside the radome model, along its surface, and in the space near it. Significant influence of the “reverse” discharge from the antenna model under the radome on the types of current impulses recorded on the antennas under impact of the artificial thunderstorm cell is established. Peculiarities of the discharge formation in the radome model when using solid and segmented diverter strips for its protection are revealed. Parameters of the current impulses registered on the diverter strips and the antennas have been determined. Based on the conducted research, the possible mechanisms of the impact of thunderclouds and lightning discharges on radio-transparent aircraft radomes and the equipment inside them are considered