| 11. |
- Kozlov, Mikhail, V, et al.
(author)
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Climate shapes the spatiotemporal variation in color morph diversity and composition across the distribution range of Chrysomela lapponica leaf beetle
- 2022
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In: Insect Science. - : John Wiley & Sons. - 1672-9609 .- 1744-7917. ; 29:3, s. 942-955
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Journal article (peer-reviewed)abstract
- Color polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. We explored the color morph diversity and composition in a Chrysomela lapponica leaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species. We obtained information on 13 617 specimens of this beetle from museums, private collections, and websites. These specimens (collected from 1830-2020) originated from 959 localities spanning 33 degrees latitude, 178 degrees longitude, and 4200 m altitude. We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism (quantified by the Shannon diversity index) and in the relative frequencies of individual color morphs. The highest level of polymorphism was found at high latitudes and altitudes. The color morphs differed in their climatic requirements; composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year, longitude, mean July temperature and between-year temperature fluctuations. The proportion of melanic beetles, in line with the thermal melanism hypothesis, increased with increasing latitude and altitude and decreased with increasing climate seasonality. Melanic morph frequencies also declined during the past century, but only at high latitudes and altitudes where recent climate warming was especially strong. The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments, presumably due to the different climatic requirements of coexisting color morphs.
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| 12. |
- Serovaiskii, A. Y., et al.
(author)
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Investigation of the LiCu2O2 Phase Samples Treated under High Thermobaric Conditions
- 2021
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In: Crystallography reports (Print). - : Pleiades Publishing Ltd. - 1063-7745 .- 1562-689X. ; 66:6, s. 1060-1065
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Journal article (peer-reviewed)abstract
- Orthorhombic lithium cuprate LiCu2O2 was exposed to high temperature and pressure of 950 degrees C and 4.5 GPa. X-ray diffraction studies indicate that the treated samples of LiCu2O2 had tetragonal symmetry, in contrast to the orthorhombic one of the phase synthesized at atmospheric pressure. Temperature dependences of dielectric permittivity epsilon and tangent of dielectric loss tan delta, as well as DC (direct current), resistivity, rho were investigated in the temperature range 77-296 K. No anomalous changes of the studied parameters inherent in the phase transitions were detected in this temperature range. The rho(T) dependences were common to semiconductors. These dependences were linearized in the Mott coordinates log rho-1/T (0.25). It indicated the variable length hopping mechanism of conduction between the next nearest neighbors in the studied samples.
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| 13. |
- Koptyug, Andrey, 1956-, et al.
(author)
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Novel Strategy in Searching for Natural Compounds with Anti-Aging and Rejuvenating Potential
- 2023
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In: International Journal of Molecular Sciences. - 1661-6596 .- 1422-0067. ; 24:9
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Journal article (peer-reviewed)abstract
- We suggest a novel approach for searching natural compounds with anti-aging and rejuvenation potential using cell cultures, with a high potential for the further in vivo applications. The present paper discusses ways of defining age for cell populations with large numbers of cells and suggests a method of assessing how young or old a cell population is based on a cell age profile approach. This approach uses experimental distributions of the cells over the cell cycle stages, acquired using flow cytometry. This paper discusses how such a profile should evolve under homeostatic maintenance of cell numbers in the proliferation niches. We describe promising results from experiments on a commercial substance claiming rejuvenating and anti-aging activity acting upon the cultures of human mononuclear cells and dermal fibroblasts. The chosen substance promotes a shift towards larger proportion of cells in synthesis and proliferation stages, and increases cell culture longevity. Further, we describe promising in vivo testing results of a selected food supplement. Based on the described concept of cell age profile and available test results, a strategy to search for natural compounds with regenerative, anti-aging and rejuvenation potential is suggested and proposed for wider and thorough testing. Proposed methodology of age assessment is rather generic and can be used for quantitative assessment of the anti-aging and rejuvenation potential of different interventions. Further research aimed at the tests of the suggested strategy using more substances and different interventions, and the thorough studies of molecular mechanisms related to the action of the substance used for testing the suggested search methodology, are needed.
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| 14. |
- Kozlov, Alexander, et al.
(author)
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Recovery of undamaged electron-density maps in the presence of damage-induced partial coherence in singe-particle imaging
- 2020
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In: IUCrJ. - 2052-2525. ; 7, s. 1114-1123
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Journal article (peer-reviewed)abstract
- Resolving the electronic structure of single biological molecules in their native state was among the primary motivations behind X-ray free-electron lasers. The ultra-short pulses they produce can outrun the atomic motion induced by radiation damage, but the electronic structure of the sample is still significantly modified from its original state. This paper explores the decoherence of the scattered signal induced by temporal evolution of the electronic structure in the sample molecule. It is shown that the undamaged electron density of a single-molecule sample can often be retrieved using only the two most occupied modes from the coherent mode decomposition of the partially coherent diffraction fluence.
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| 15. |
- Wells, Daniel J., et al.
(author)
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Observations of phase changes in monoolein during high viscous injection
- 2022
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In: Journal of Synchrotron Radiation. - : International Union Of Crystallography. - 0909-0495 .- 1600-5775. ; 29:3, s. 602-614
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Journal article (peer-reviewed)abstract
- Serial crystallography of membrane proteins often employs high-viscosity injectors (HVIs) to deliver micrometre-sized crystals to the X-ray beam. Typically, the carrier medium is a lipidic cubic phase (LCP) media, which can also be used to nucleate and grow the crystals. However, despite the fact that the LCP is widely used with HVIs, the potential impact of the injection process on the LCP structure has not been reported and hence is not yet well understood. The self-assembled structure of the LCP can be affected by pressure, dehydration and temperature changes, all of which occur during continuous flow injection. These changes to the LCP structure may in turn impact the results of X-ray diffraction measurements from membrane protein crystals. To investigate the influence of HVIs on the structure of the LCP we conducted a study of the phase changes in monoolein/water and monoolein/buffer mixtures during continuous flow injection, at both atmospheric pressure and under vacuum. The reservoir pressure in the HVI was tracked to determine if there is any correlation with the phase behaviour of the LCP. The results indicated that, even though the reservoir pressure underwent (at times) significant variation, this did not appear to correlate with observed phase changes in the sample stream or correspond to shifts in the LCP lattice parameter. During vacuum injection, there was a three-way coexistence of the gyroid cubic phase, diamond cubic phase and lamellar phase. During injection at atmospheric pressure, the coexistence of a cubic phase and lamellar phase in the monoolein/water mixtures was also observed. The degree to which the lamellar phase is formed was found to be strongly dependent on the co-flowing gas conditions used to stabilize the LCP stream. A combination of laboratory-based optical polarization microscopy and simulation studies was used to investigate these observations.
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