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The review analyzes and summarizes the latest literature on the history of development and the current state of methodological approaches to the identification and quantification of phytohormones in plant tissues. Phytohormones play a key role in the regulation of physiological processes throughout the life cycle of plants – from seed germination to aging. In tissues of plants, their concentrations are very low (from 10-9 M to 10-6 M), so the development of fast, highly efficient, comprehensive, and at the same time reliable approaches to the determination of phytohormones is extremely urgent. The article gives a brief description of the main classes of phytohormones, describes their functional activity. The substantiated and checked sequence of procedures on the extraction of plant hormones, their separation from interfering substances, quantification methodology for indol-3-acetic, abscisic, gibberellic (GA3), salicylic acids and five cytokinins that combines a high-performance liquid chromatography with mass spectrometry are presented. The article describes four chromatographic methods of profiling, gives the conditions for detecting phytohormones of different classes and ionization of these substances in a mass spectrometer. The importance of phytohormones profiling in plant tissues for further applied in biotechnological approaches, in particular in metabolic engineering, for the formation of stress resistance in crops is discussed.

The review analyzes and summarizes information on the history of development and the current state of methodological approaches to the qualitative and quantitative determination of phytohormones in plant tissues. Plant hormones play an indispensable role in many physiological processes during a plant life cycle, from seed’s germination to senescence. The determination of the endogenous hormones concentration is essential for elucidating the role of a particular hormone in any physiological process. A sensitive and quick analytical method of a simultaneous quantitative estimation of the main classes of phytohormones is essential for the investigation of signaling control networks in specific developmental pathways and physiological responses. In plant tissues, phytohormones are present in very low concentrations (from 10-9 M to 10-6 M); hence, the availability of highly effective, comprehensive and reliable analytical techniques for their identification is extremely important. The article gives a brief description of the main classes of plant hormones and outlines their functional activity. The importance of methods for hormones identification in plant tissues and their use in plant physiology and agricultural practice is discussed. The study presents a valid and tested sequence of procedures for the extraction of plant hormones, a methodology for purification of the obtained extracts from interfering substances and an up-to-date method of plant hormones quantification (indole-3-acetic, abscisic, gibberellic, salicylic acids and five forms of cytokinins). The quantification method combines a high-performance liquid chromatography with a mass spectrometry. Four chromatographic methods for the sepa­ration and detection of substances in aliquots as well as ionization conditions for hormones in a mass spectrometer are described. The presented analytical technique is adapted for scientific laboratories in Ukraine.

Regulation of growth and development of cultivated plants in order to optimize the production process is one of the main objectives of modern plant physiology. Both activators and growth inhibitors are used for this purpose. The effect of foliar treatment with 0.005% solution of gibberellic acid and 0.025% solution of antigibberellic preparation of tebuconazole on the morphogenesis, leaf structure, photosynthetic pigment content, balance of phytohormones and eggplant productivity cv. Diamond variety was investigated. The treatment with the preparations was carried out in the budding phase. The vegetation experiment was laid under soil and sand culture in vessels of a ten-liter capacity. The morphometric parameters were determined every 10 days, the mesostructure was studied in the leaves of the middle tier in the phase of fruit formation, chlorophyll content was measured in the raw material by spect­rophotometric method. Analytical determination of phytohormones (indole-3-acetic acid, gibberellic, abscisic acids and cytokinins – zeatin, zeatin-O-glucoside, zeatinriboside, isopentenyladenine and isopentenyladenosine) was performed by high performance liquid chromatography. Under the action of gibberellic acid, plant height increased significantly, and it decreased after its treatment with tebuconazole. The stimulator and inhibitor increased the number of leaves per plant, the weight of the leaf dry matter, the area of the individual leaf blade and the area of leaves per plant. Both preparations increased the weight of the raw material of the stems and roots, as well as the mass of dry matter of the whole plant. Under the action of tebuconazole, the content of chlorophylls in the leaves increased, while under the action of gibberellic acid it decreased. After treatment with gibberellic acid and tebuconazole, the thickness of the leaf blade increased due to chlorenchyma thickening. In the variant with gibberellic acid, the thickness of upper and lower epidermis increased, and in the variant with tebuconazole, these parameters decreased. Both growth regulators increased the volume of cells of the columnar parenchyma. The contet of endogenous gibberellic, indole-3-acetic and abscisic acids of the stems and especially in the leaves increased with the treatment of exogenous gibberellic acid, whereas after the application of tebuconazole the gibberellic and indole-3-acetic acid content of the stems decreased significantly and practically decreased to traces. Instead, the amount of abscisic acid increased. After treatment with exogenous gibberellic acid, the pool of cytokinins in the leaves significantly decreased. The inactive isoforms of the hormone zeatin-O-glucoside and isopentenyladenosine dominated in the stems. The effect of tebuconazole decreased the pool of cytokinins in the stems and increased in the leaves. In general, due to the multidirectional action, growth regulators positively influenced the elements of eggplant productivity. More effective was the retardant – tebuconazole. Therefore, the anatomic-morphological and structural-functional rearrangements in eggplants under the effects of exogenous gibberellic acid and tebuconazole are due to changes in the balance and distribution of endogenous hormones. Increased photosynthetic activity, stimulation of growth processes of some organs of the plant and inhibition of others enlarged the biological productivity of the culture.

Plants of heterosporous annual fern hydrophyte Salvinia natans L. were collected in ponds of the Desniansky district of Kyiv city during summer time beginning from June, 2015 at one-month interval. Biometric studies of the whole plant (clone) and some segments of floating and submerged fronds showed that changes in the sporophyte weight and length at the various phenological phases of development occurred mostly owing to newly formed organs (modules) while linear dimensions of some formed fronds remained practically unchanged. The weight and length of an individual submerged frond considerably exceeded those of floating one. At the steady-state growth phase (July) the weight of an individual submerged frond increased two times due to an intensive formation of multi-cellular filamentous hairs while the length remained almost unchanged. During the reproductive development (August-September) the sporophyte weight increased as a result of sporocarps formation. The pattern of IAA accumulation and localization in organs of the sporophyte S. natans was for the first time analyzed using HPLC. At the phase of a fern intensive growth (June), the total IAA content of floating and submerged fronds was shown to be similarly high and reached 182 ng/g of fresh weight. During an active overgrowth and pubescence of submerged fronds (July) the endogenous IAA content was 546.3 ng/g of fresh weight while the quantity of this hormone in floating fronds remained at the level of the previous phase. A considerable reduction of this hormone content in ageing floating and submerged fronds was observed following the sporogenesis beginning at the phase of sporocarp formation and spore ripening. At the stage of late sporogenesis in the beginning of vegetative organs dying phase (September), the total IAA content in sporocarps that contained mature spores was 193 ng/g of fresh weight. The free hormone form dominated at the stage of an active and steady-state growth of floating and submerged fronds. Conjugated IAA was localized mostly in submerged fronds in quantity which exceeded that of floating ones 4 and 36 times, respectively. Distribution of this hormone between floating and submerged fronds shows that during the steady-state growth phase IAA is localized in submerged fronds, while at the phase of vegetative organs dying – in sporocarps. Specific changes in accumulation and localization of endogenous IAA revealed the correlation between growth processes and distribution, and content of phytohormone free and conjugated forms in sporophyte vegetative and reproductive organs of S. natans water fern during its individual development.

Analytical formula for the equation of the neutron scattering for isotropic neutron source, which includes the temperature of the moderating medium as the parameter, was first obtained in the given work in the framework of gas model of the medium. The obtained equation of the scattering is based on the solution of the kinematic problem of elastic scattering of neutron at the nucleus in “L”-system in general case, when before the scattering not only neutron but the nucleus also have the arbitrary velocity vector in “L”-system of coordinates. The neutron flux and moderating spectra depending on the media temperature were found for this new equation of the scattering. Obtained expression for the moderating neutron spectra allows the new interpretation of the processes, which determine neutron spectra in the thermal area.

Phytohormonal balance changes in plants with contrast salt resistance – glycophyte Phaseolus vulgaris L. and halophyte Mesembryanthemum crystallinum L. – under salt stress (NaCl) were studied. It was assumed that salt tolerance of M. crystallinum is dependent on hormonal balance peculiarities, namely on, extremely low ABA level combined with high amount of IAA and cytokinins.

Listeners with hearing loss have difficulty processing sounds in noisy environments. This is most noticeable for speech perception, but is reflected in a basic auditory processing task: detecting a tonal signal in a noise background, i.e. simultaneous masking. It is unresolved whether the mechanisms underlying simultaneous masking arise from the auditory periphery or from the central auditory system. Poor detection in listeners with sensorineural hearing loss (SNHL) is attributed to cochlear hair cell damage. However, hearing loss alters neural processing in the central auditory system. Additionally, both psychophysical and neurophysiological data from normally hearing and impaired listeners suggest that there are additional contributions to simultaneous masking that arise centrally. With SNHL, it is difficult to separate peripheral from central contributions to signal detection deficits. We have thus excluded peripheral contributions by using an animal model of early conductive hearing loss (CHL) that provides auditory deprivation but does not induce cochlear damage. When tested as adults, animals raised with CHL had increased thresholds for detecting tones in simultaneous noise. Furthermore, intracellular in vivo recordings in control animals revealed a cortical correlate of simultaneous masking: local cortical processing reduced tone-evoked responses in the presence of noise. This raises the possibility that altered cortical responses which occur with early CHL can influence even simple signal detection in noise.

The central nucleus of the inferior colliculus (IC) is a major integrative center in the central auditory system. It receives information from both the ascending and descending auditory pathways. To determine how single IC neurons integrate information over a wide range of sound frequencies and sound levels, we examined their intracellular responses to frequency-modulated (FM) sounds in awake little brown bats (Myotis lucifugus). Postsynaptic potentials were recorded in response to downward FM sweeps of the range typical for little brown bats (80–20 kHz) and to three FM subcomponents (80–60, 60–40, and 40–20 kHz). The majority of recorded neurons responded to the 80- to 20-kHz downward FM sweep with a complex response. In this response an initial hyperpolarization was followed by depolarization with or without spike followed by hyperpolarization. Intracellular recordings in response to three FM subcomponents revealed that these neurons receive excitatory and inhibitory inputs from a wide range of sound frequencies. One third of IC neurons performed nearly linear temporal summation across a wide range of sound frequencies, whereas two thirds of IC neurons exhibited nonlinear summation with different degrees of nonlinearity. Some IC neurons showed different latencies of postsynaptic potentials in response to different FM subcomponents. Often responses to the later FM subcomponent occurred before responses to the earlier ones. This phenomenon may be responsible for response selectivity of IC neurons to FM sweeps. [ABSTRACT FROM AUTHOR]