First Detection of Potato Spindle Tuber Viroid in Natural Isolates of Potato Blight Agent Phytophthora infestans.

Phytophthora infestans is the oomycete that causes potato blight, an important disease. The potato spindle tuber viroid (PSTVd) is a dangerous pathogen of many plants, including potato. We have previously shown that PSTVd can be transmitted from infected potato plants into the Ph. infestans mycelium, replicated within the mycelium, and then transmitted to other potato plants upon their infection with Ph. infestans in laboratory conditions. The objective of this work was to check the hypothesis that PSTVd transmission, preservation, and replication in Ph. infestans are possible to occur in natural conditions during long-term coevolution of the host and pathogen in the Solanum spp.-Ph. infestans system. A screening test for PSTVd was performed in 111 natural Ph. infestans isolates obtained from potato plants, which represented various cultivars, had signs of potato blight, and were collected from industrial potato fields of the Moscow, Vologda, and Bryansk regions and breeding and variety test plots of the St. Petersburg and Moscow regions in 2020 and 2022. Using RT-PCR with PSTVd-specific primers, 42 Ph. infestans isolates collected in 2020 were tested after five passages and 69 Ph. infestans isolates collected in 2022, after a single passage on rye agar. Diagnostic amplicons were detected in 8 and 50 isolates, respectively. Some of the amplicons were visually assessed as minor amplification products, apparently resulting from nonspecific priming on a host Ph. infestans gene, which codes for a hypothetical protein-coding mRNA in Ph. infestans and other oomycetes. Eight amplicons were sequenced to verify the PSTVd presence in Ph. infestans isolates. Three amplicons corresponded to the complete PSTVd genome and five, to its part (~260 bp). The nucleotide sequences of cloned amplification products were identified to species in the BLAST system and deposited in GenBank. The amplicons obtained with the PSTVd-specific primers were identified as PSTVd sequences in all Ph. infestans isolates examined. The majority of the nucleotide sequences were phylogenetically related to BLAST sequences of PSTVd strains originating from Russia; several strains showed similarity to strains from other countries (France, China, and West African countries). The results demonstrate that PSTVd was for the first time detected in natural (field) Ph. infestans isolates and offer new opportunities for studying the intricate multilevel host-parasite interactions.

Selective slow-wave sleep suppression affects glucose tolerance and melatonin secretion. The role of sleep architecture.

OBJECTIVES: Our study aimed to assess the impact of one night of slow-wave sleep (SWS) suppression on glucose tolerance, and explore whether melatonin plays a role in glucose tolerance impairment after SWS suppression. METHODS: In sum, 20 volunteers participated in two experimental sessions: a session with SWS suppression during one night's sleep and a session with a regular night's sleep (control). Each session included collecting seven salivary samples. The following morning, an oral glucose tolerance test (OGTT) was performed. RESULTS: SWS suppression effects depended on the individual blood glucose response to the OGTT. During the control session, 'responders' (N = 11), already presented with low glucose tolerance, which further declined after SWS suppression. 'Non-responders' (N = 9) experienced high glucose tolerance in both conditions. Among the responders, SWS suppression led to an increase in melatonin at the moment of awakening, while in non-responders melatonin increased during the first half of the night. In both conditions, responders were characterized by a shorter total sleep time (TST) and less rapid eye movement (REM) sleep. During SWS suppression, they had more non-rapid eye movement (NREM) stage 1 and longer nocturnal wakefulness. Responders and non-responders showed a comparable amount of SWS. CONCLUSIONS: This study highlights three key findings: first, SWS suppression leads to an increase in salivary melatonin; second, melatonin's effect on glucose tolerance depends on its secretion timing; and third, durations of REM sleep and nocturnal awakenings, appear to play an important role in melatonin secretion and glucose tolerance, indicating the potential clinical relevance of these findings for type 2 diabetes risk assessment.

Slow-wave sleep and androgens: selective slow-wave sleep suppression affects testosterone and 17α-hydroxyprogesterone secretion.

OBJECTIVES: Levels of steroid hormones such as androgens and cortisol exhibit circadian variation, and their fluctuations are related to the sleep-wake cycle. Currently, the functional role of different stages of sleep in steroid hormone secretion remains unclear. The present study aims to explore the effect of slow-wave sleep (SWS) suppression on morning levels of cortisol and androgens. METHODS: Twelve healthy male volunteers participated in two experimental sessions: a session with selective SWS suppression during night sleep and a session with regular night sleep (control). SWS suppression was achieved by stimulation using an acoustic tone. Salivary samples were collected in the morning immediately after awakening and again 40 min later. The samples were analysed by liquid chromatography-tandem mass spectrometry for testosterone, androstenedione (Ad), dehydroepiandrosterone (DHEA), 17α-hydroxyprogesterone (17-OHP), and cortisol. RESULTS: SWS suppression reduced overall SWS duration by 54.2% without significant changes in total sleep time and sleep efficiency. In the session with selective SWS suppression, the average level of morning testosterone was lower than in the control session (p = 0.017). Likewise, 17-OHP was lower in the SWS suppression condition (p = 0.011) whereas the ratio of DHEA/Ad was higher (p = 0.025). There were no significant differences between sessions in cortisol, Ad, or DHEA concentrations. CONCLUSIONS: The effect of selective SWS suppression on morning levels of testosterone and 17-OHP points to the importance of SWS for the synthesis and secretion of androgens. These results suggest that chronic sleep problems, which lead to reduced SWS, increase the risk for the development of androgen deficiency in the long term.

Proton and oxygen ion conductivity in the pyrochlore/fluorite family of Ln2-xCaxScMO7-δ (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1) niobates and tantalates.

The tolerance factor is a good criterion to understand the structural transitions in Ln2-xCaxScMO7-δ (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1). Decreasing the Ln ionic radius in Ln2ScNb(Ta)O7 leads to a morphotropic transition from a pyrochlore to a fluorite-like structure. Ca2+-doping leads to a pyrochlore-to-fluorite transition in Ln2-xCaxScMO7-δ (Ln = La, Sm) and a fluorite-to-pyrochlore transition in Ho2-xCaxScNbO7-δ. Proton contribution to the total conductivity was observed for Ln2-xCaxScNb(Ta)O7-δ (Ln = La, Sm; x = 0, 0.05, 0.1) 3+/5+ pyrochlores and the maximum proton contribution was shown by Sm1.9Ca0.1ScMO6.95 (M = Nb, Ta), which are located at the boundary between pyrochlores and fluorites (comparative study of electrical conduction and oxygen diffusion). Proton conduction of Sm1.9Ca0.1ScNbO6.95 and Sm1.9Ca0.1ScTaO6.95 pyrochlores persists up to 800 and 850 °C, respectively. The conductivity of fluorite-like Ho2-xCaxScNbO7-δ (x = 0, 0.05) and Yb2ScNbO7 is dominated by the oxygen ion transport, in accordance with their energy activation values 1.09-1.19 eV. The dielectric permittivity and TG studies were used for the investigation of oxygen vacancy dynamics and water incorporation into the Ln2-xCaxScNb(Ta)O7-δ (Ln = La, Sm, Ho, Yb; x = 0, 0.05, 0.1) lattice. It is shown that oxygen vacancy-related dielectric relaxation in the range of 550-650 °C (ambient air), typical of pyrochlores and fluorites with pure oxygen ion conductivity, decreases and disappears for proton-conducting oxides.

Nanocomposites based on poly-D,L-lactide and multiwall carbon nanotubes.

A possibility of poly-D,L-lactide modification by multiwall carbon nanotubes (MWCNT) has been shown. MWCNT were prepared from methane-air mixture upon atmospheric pressure without catalyst on high voltage atmospheric pressure discharge plasma set-up. According to scanning and transmission electronic microscope data carbon nanotubes diameters were within 12-60 nm. Quantities of MWCNT incorporated did not exceed 0.5%. Nanocomposites were obtained by sonification of mixture of a poly-D,L-lactide solution in chloroform and MWCNT followed by film casting on glass substrates. Tensile strength and thermomechanical properties of the dried composite films were investigated. Introduction of MWCNT into poly-D,L-lactide has been shown to cause the enhanced polymer stability to thermal oxidative destruction. Taking into account the results obtained one could anticipate that implants from nanocomposites of poly-D,L-lactide with MWCNT would be dispersed in a living organism more slowly as compared to implants from pure poly-D,L-lactide without additives.

[Analysis of contact interfaces of HIV reverse transcriptase subunits].

Analysis of structure and features of subunit contact areas of reverse transcriptase (RT) HIV was done. The amino acid residues from contact areas of RT subunits are more conservative than the rest residues of the protein. Estimation of contribution of the amino acid residues from contact areas in binding energy of subunits showed that binding energy is mostly localized on the several amino acid residues of the dimer interface (hot spots). The majority of these hot spots form several clusters on contact surfaces. Analysis of these clusters allows to predict the region on the contact area of protein dimer that can be useful for design the inhibitors of dimerization of RT HIV.