Mechanisms underlying LncRNA SNHG1 regulation of Alzheimer's disease involve DNA methylation.

Alzheimer's disease (AD) is a neurodegenerative disease associated with long non-coding RNAs and DNA methylation; however, the mechanisms underlying the role of lncRNA small nucleolar RNA host gene 1 (lncRNA SNHG1) and subsequent involvement of DNA methylation in AD development are not known. The aim of this study was to examine the regulatory mechanisms attributed to lncRNA SNHG1 gene utilizing 2 strains of senescence-accelerated mouse prone 8 (SAMP8) model of AD and compared to senescence-accelerated mouse resistant (SAMR) considered a control. Both strains of the mouse were transfected with either blank virus, psLenti-U6-SNHG1(low gene expression) virus, and psLenti-pA-SNHG1(gene overexpression) virus via a single injection into the brains for 2 weeks. At 2 weeks mice were subjected to a Morris water maze to determine any behavioral effects followed by sacrifice to extract hippocampal tissue for Western blotting to measure protein expression of p-tau, DNMT1, DNMT3A, DNMT3B, TET1, and p-Akt. No marked alterations were noted in any parameters following blank virus transfection. In SAMP8 mice, a significant decrease was noted in protein expression of DNMT1, DNMT3A, DNMT3B, and p-Akt associated with rise in p-tau and TET1. Transfection with ps-Lenti-U6-SNHG1 alone in SAMR1 mice resulted in a significant rise in DNMTs and p-Akt and a fall in p-tau and TET1. Transfection of SAMP8 with ps-Lenti-U6-SNHG1 blocked effects on overexpression noted in this mouse strain. However, knockdown of lncRNA SNHG1 yielded the opposite results as found in SAMR1 mice. In conclusion, the knockdown of lncRNA SNHG1 enhanced DNA methylation through the PI3K/Akt signaling pathway, thereby reducing the phosphorylation levels of tau in SAMP8 AD model mice with ameliorating brain damage attributed to p-tau accumulation with consequent neuroprotection.

A New Species of Ganoderma (Ganodermataceae, Polyporales) from Southern China and Optimum Condition for Mycelia Production.

The present study sought to propose Ganoderma guixiense sp. nov. as a new species based on phenotypic and genotypic evidence. Phylogenetic analyses were carried out based on the internal transcribed spacer (ITS), the large subunit of nuclear ribosomal RNA gene (nLSU), and the second subunit of RNA polymerase II (RPB2) sequence data. G. guixiense has been characterized by pileate basidiomata, long stipe, in addition to reddish-black zonate pileal surface. Basidiospores are broadly ellipsoid with one end tapering at maturity, and measuring 9-12.8 × 6.5-9.3 µm. Basidia are oval to subglobose. This study marks the first exploration of the biological characteristics of G. guixiense. The result indicated that the optimal medium of mycelial growth was observed on malt extract agar (MEA) and yeast extract peptone dextrose agar (YPD) while the optimal temperature was found to be 25-30 °C with pH range of 6-7.

Dinuclear Complexes of Uranyl, Neptunyl, and Plutonyl: Structures and Oxidation States Revealed by Experiment and Theory.

Dinuclear perchlorate complexes of uranium, neptunium, and plutonium were characterized by reactivity and DFT, with results revealing structures containing pentavalent, hexavalent, and heptavalent actinyls, and actinyl-actinyl interactions (AAIs). Electrospray ionization produced native complexes [(AnO2)2(ClO4)3]- for An:An = U:U, Np:Np, Pu:Pu, and Np:Pu, which are intuitively formulated as actinyl(V) perchlorates. However, DFT identified lower-energy structures [(AnO2)(AnO3)(ClO4)2(ClO3)]- comprising a perchlorate fragmented to ClO3, actinyl(VI) cation AnVIO22+, and neutral AnO3. For U:U and Np:Np, and Np in Np:Pu, the coordinated AnO3 is calculated as actinyl(VI) with an equatorial oxo, [Oyl═AnVI═Oyl][═Oeq], whereas for Pu:Pu, it is plutonyl(V) oxyl, [Oyl═PuV═Oyl][-Oeq•]. The implied lower stability of PuVI versus NpVI indicates weaker Pu═Oeq versus Np═Oeq bonding. Adsorption of O2 by the U:U complex suggests oxidation of UV to UVI, corroborating the assignment of perchlorate [(AnVO2)2(ClO4)3]-. DFT predicts the O2 adducts are [(AnVIO2)(O2)(AnVIO2)(ClO4)3]- with actinyls oxidized from +V to +VI by bridging peroxide, O22-. In accordance with reactivity, O2- addition is computed as substantially exothermic for U:U and least favorable for Pu:Pu. Collision-induced dissociation of native complexes eliminated ClO2 to yield [(AnO2)(O)2(AnO2)(ClO4)2]-, in which fragmented O atoms bridge as oxyl O-• and oxo O2- to yield uranyl(VI) and plutonyl(VI), or as oxos O2- to yield neptunyl(VII), [Oyl═NpVII═Oyl]3+.

Involvement of 5f Orbitals in the Covalent Bonding between the Uranyl Ion and Trialkyl Phosphine Oxide: Unraveled by Oxygen K-Edge X-ray Absorption Spectroscopy and Density Functional Theory.

Monodentate organophosphorus ligands have been used for the extraction of the uranyl ion (UO22+) for over half a century and have exhibited exceptional extractability and selectivity toward the uranyl ion due to the presence of the phosphoryl group (O═P). Tributyl phosphate (TBP) is the extractant of the world-renowned PUREX process, which selectively recovers uranium from spent nuclear fuel. Trialkyl phosphine oxide (TRPO) shows extractability toward the uranyl ion that far exceeds that for other metal ions, and it has been used in the TRPO process. To date, however, the mechanism of the high affinity of the phosphoryl group for UO22+ remains elusive. We herein investigate the bonding covalency in a series of complexes of UO22+ with TRPO by oxygen K-edge X-ray absorption spectroscopy (XAS) in combination with density functional theory (DFT) calculations. Four TRPO ligands with different R substituents are examined in this work, for which both the ligands and their uranyl complexes are crystallized and investigated. The study of the electronic structure of the TRPO ligands reveals that the two TRPO molecules, irrespective of their substituents, can engage in σ- and π-type interactions with U 5f and 6d orbitals in the UO2Cl2(TRPO)2 complexes. Although both the axial (Oyl) and equatorial (Oeq) oxygen atoms in the UO2Cl2(TRPO)2 complexes contribute to the X-ray absorption, the first pre-edge feature in the O K-edge XAS with a small intensity is exclusively contributed by Oeq and is assigned to the transition from Oeq 1s orbitals to the unoccupied molecular orbitals of 1b1u + 1b2u + 1b3u symmetries resulting from the σ- and π-type mixing between U 5f and Oeq 2p orbitals. The small intensity in the experimental spectra is consistent with the small amount of Oeq 2p character in these orbitals for the four UO2Cl2(TRPO)2 complexes as obtained by Mulliken population analysis. The DFT calculations demonstrate that the U 6d orbitals are also involved in the U-TRPO bonding interactions in the UO2Cl2(TRPO)2 complexes. The covalent bonding interactions between TRPO and UO22+, especially the contributions from U 5f orbitals, while appearing to be small, are sufficiently responsible for the exceptional extractability and selectivity of monodentate organophosphorus ligands for the uranyl ion. Our results provide valuable insight into the fundamental actinide chemistry and are expected to directly guide actinide separation schemes needed for the development of advanced nuclear fuel cycle technologies.

Creation of an unexpected plane of enhanced covalency in cerium(III) and berkelium(III) terpyridyl complexes.

Controlling the properties of heavy element complexes, such as those containing berkelium, is challenging because relativistic effects, spin-orbit and ligand-field splitting, and complex metal-ligand bonding, all dictate the final electronic states of the molecules. While the first two of these are currently beyond experimental control, covalent M‒L interactions could theoretically be boosted through the employment of chelators with large polarizabilities that substantially shift the electron density in the molecules. This theory is tested by ligating BkIII with 4'-(4-nitrophenyl)-2,2':6',2"-terpyridine (terpy*), a ligand with a large dipole. The resultant complex, Bk(terpy*)(NO3)3(H2O)·THF, is benchmarked with its closest electrochemical analog, Ce(terpy*)(NO3)3(H2O)·THF. Here, we show that enhanced Bk‒N interactions with terpy* are observed as predicted. Unexpectedly, induced polarization by terpy* also creates a plane in the molecules wherein the M‒L bonds trans to terpy* are shorter than anticipated. Moreover, these molecules are highly anisotropic and rhombic EPR spectra for the CeIII complex are reported.

Proton affinities of pertechnetate (TcO4-) and perrhenate (ReO4-).

The anions pertechnetate, TcO4-, and perrhenate, ReO4-, exhibit very similar chemical and physical properties. Revealing and understanding disparities between them enhances fundamental understanding of both. Electrospray ionization generated the gas-phase proton bound dimer (TcO4-)(H+)(ReO4-). Collision induced dissociation of the dimer yielded predominantly HTcO4 and ReO4-, which according to Cooks' kinetic method indicates that the proton affinity (PA) of TcO4- is greater than that of ReO4-. Density functional theory computations agree with the experimental observation, providing PA[TcO4-] = 300.1 kcal mol-1 and PA[ReO4-] = 297.2 kcal mol-1. Attempts to rationalize these relative PAs based on elementary molecular parameters such as atomic charges indicate that the entirety of bond formation and concomitant bond disruption needs to be considered to understand the energies associated with such protonation processes. Although in both the gas and solution phases, TcO4- is a stronger base than ReO4-, it is noted that the significance of even such qualitative accordance is tempered by the very different natures of the underlying phenomena.

A Computational Assessment of Actinide Dioxide Cations AnO22+ for An = U to Lr: The Limited Stability Range of the Hexavalent Actinyl Moiety, [O═An═O]2.

The isolated gas-phase actinide dioxide dications, AnO22+, were evaluated by DFT and coupled cluster CCSD(T) calculations for 12 actinides, An = U-Lr. CASSCF calculations were used to define the orbitals for the CCSD(T) calculations. The characteristic linear [O═An═O]2+ hexavalent actinyl(VI) was found to be the lowest energy structure for An = U, Np, and Pu, which also form stable actinyl(VI) species in solution and possibly for Am when spin-orbit effects are included. For Am, there is a divalent [AnII(O2)]2+ structure where the dioxygen is an end-on physisorbed η1-3O2 2 kcal/mol above the actinyl when spin-orbit effects are included which lower the energy of the actinyl structure. For An = Cm, Bk, and Lr, the lowest energy structure is trivalent [AnIII(O2-)]2+ where the dioxygen is a side-on superoxide, η2-O2-. For Cm, the actinyl is close in energy to the ground state when spin-orbit effects are included. For An = Cf, Es, Fm, Md, and No, the lowest energy structure is divalent [AnII(O2)]2+ where the dioxygen is an end-on physisorbed η1-3O2. The relative energies suggest that curyl(VI) and berkelyl(VI), like well-known americyl(VI), might be stabilized by coordinating ligands in condensed phases. The results further indicate that for californyl and beyond, the actinyl(VI) moieties will probably be elusive even using strong donor ligands. The prevalence of low oxidation states (OSs) An(II) and An(III) for transplutonium actinides reflects stabilization of the 5f orbitals and validates established trends, including the remarkably high stability of divalent No. Bond distances and other parameters suggest maximum bond covalency around plutonyl(VI), with a particularly substantial decrease in bond strength between americyl(VI) and curyl(VI).

Gas-Phase Complexes of Americium and Lanthanides with a Bis-triazinyl Pyridine: Reactivity and Bonding of Archetypes for F-Element Separations.

Bis-triazinyl pyridines (BTPs) exhibit solution selectivity for trivalent americium over lanthanides (Ln), the origins of which remain uncertain. Here, electrospray ionization was used to generate gas-phase complexes [ML3]3+, where M = La, Lu, or Am and L is EtBTP 2,6-bis(5,6-diethyl-1,2,4-triazin-3-yl)-pyridine. Collision-induced dissociation (CID) of [ML3]3+ in the presence of H2O yielded a protonated ligand [L(H)]+ and hydroxide [ML2(OH)]2+ or hydrate [ML(L-H)(H2O)]2+, where (L-H)- is a deprotonated ligand. Although solution affinities indicate stronger binding of BTPs toward Am3+ versus Ln3+, the observed CID process is contrastingly more facile for M = Am versus Ln. To understand the disparity, density functional theory was employed to compute potential energy surfaces for two possible CID processes, for M = La and Am. In accordance with the CID results, both the rate determining transition state barrier and the net energy are lower for [AmL3]3+ versus [LaL3]3+ and for both product isomers, [ML2(OH)]2+ and [ML(L-H)(H2O)]2+. More facile removal of a ligand from [AmL3]3+ by CID does not necessarily contradict stronger Am3+-L binding, as inferred from solution behavior. In particular, the formation of new bonds in the products can distort kinetics and thermodynamics expected for simple bond cleavage reactions. In addition to correctly predicting the seemingly anomalous CID behavior, the computational results indicate greater participation of Am 5f versus La 4f orbitals in metal-ligand bonding.

A Comparative Study of Two Tube Feeding Methods in Patients with Dysphagia After Stroke: A Randomized Controlled Trial.

BACKGROUND: Dysphagia is a common symptom seen in stroke patients, it not only affects patients' nutrition supply, but also causes aspiration pneumonia. To solve the problem of nutritional support for patients with dysphagia after stroke, nasogastric tubes are routinely indwelling to provide nutrition in China. However, this feeding method sometimes causes food reflux, aspiration, pneumonia, and often affects the patients' comfort and self-image acceptance. AIM: The aim of this study was to determine whether a new feeding method called intermittent oroesophageal (IOE) tube feeding compared with continuous nasogastric tube feeding as a practical and beneficial mean of decreasing the rate of stroke associated pneumonia (SAP), and improving patients' swallowing function, comfort, psychological status. DESIGN: This was an assessor-blinded, single-center, randomized controlled trial. METHODS: Ninety-seven hospitalized stroke patients with dysphagia in the rehabilitation department from January to December 2018 were randomized to a control group and an intervention group. Patients in both groups received routine nursing, rehabilitation treatment and swallowing therapy. Patients in the intervention group were given IOE tube feeding, while those in the control group were fed by indwelling nasogastric tube. Outcomes were assessed at admission, discharge or the end of the tube feeding. RESULTS: The incidence of SAP in the intervention group was 16.33% lower than that (31.25%) in the control group; the comfort score (2.08 ± .64), anxiety score (10.98 ± 2.28), depression score (7.39 ± 2.16) were lower than those (3.02 ± .70), (12.10 ± 2.18), (8.42 ± 2.34) in the control group. The improvement rate of swallowing function in the intervention group was 83.67% higher than that (66.67%) in the control group (all P < .05). CONCLUSIONS: The IOE tube feeding compared with continuous tube feeding may reduce the incidence of SAP, and improve patients' swallowing function, comfort, psychological status in patients with dysphagia after stroke.

Activation of Water by Pentavalent Actinide Dioxide Cations: Characteristic Curium Revealed by a Reactivity Turn after Americium.

Swapping of an oxygen atom of water with that of a pentavalent actinide dioxide cation, AnO2+ also called an "actinyl", requires activation of an An-O bond. It was previously found that such oxo exchange in the gas phase occurs for the first two actinyls, PaO2+ and UO2+, but not the next two, NpO2+ and PuO2+. The An-O bond dissociation energies (BDEs) decrease from PaO2+ to PuO2+, such that the observation of a parallel decrease in the An-O bond reactivity is intriguing. To elucidate oxo exchange, we here extend experimental studies to AmO2+, americyl(V), and CmO2+, curyl(V), which were produced in remarkable abundance by electrospray ionization of Am3+ and Cm3+ solutions. Like other AnO2+, americyl(V) and curyl(V) adsorb up to four H2O molecules to form tetrahydrates AnO2(H2O)4+ with the actinide hexacoordinated by oxygen atoms. It was found that AmO2+ does not oxo-exchange, whereas CmO2+ does, establishing a "turn" to increasing the reactivity from americyl to curyl, which validates computational predictions. Because oxo exchange occurs via conversion of an actinyl(V) hydrate, AnO2(H2O)+, to an actinide(V) hydroxide, AnO(OH)2+, it reflects the propensity for actinyl(V) hydrolysis: PaO2+ hydrolyzes and oxo-exchanges most easily, despite the fact that it has the highest BDE of all AnO2+. A reexamination of the computational results for actinyl(V) oxo exchange reveals distinctive properties and chemistry of curyl(V) species, particularly CmO(OH)2+.

Probing the structures and bonding of size-selected boron and doped-boron clusters.

Because of their interesting structures and bonding and potentials as motifs for new nanomaterials, size-selected boron clusters have received tremendous interest in recent years. In particular, boron cluster anions (Bn-) have allowed systematic joint photoelectron spectroscopy and theoretical studies, revealing predominantly two-dimensional structures. The discovery of the planar B36 cluster with a central hexagonal vacancy provided the first experimental evidence of the viability of 2D borons, giving rise to the concept of borophene. The finding of the B40 cage cluster unveiled the existence of fullerene-like boron clusters (borospherenes). Metal-doping can significantly extend the structural and bonding repertoire of boron clusters. Main-group metals interact with boron through s/p orbitals, resulting in either half-sandwich-type structures or substitutional structures. Transition metals are more versatile in bonding with boron, forming a variety of structures including half-sandwich structures, metal-centered boron rings, and metal-centered boron drums. Transition metal atoms have also been found to be able to be doped into the plane of 2D boron clusters, suggesting the possibility of metalloborophenes. Early studies of di-metal-doped boron clusters focused on gold, revealing ladder-like boron structures with terminal gold atoms. Recent observations of highly symmetric Ta2B6- and Ln2Bn- (n = 7-9) clusters have established a family of inverse sandwich structures with monocyclic boron rings stabilized by two metal atoms. The study of size-selected boron and doped-boron clusters is a burgeoning field of research. Further investigations will continue to reveal more interesting structures and novel chemical bonding, paving the foundation for new boron-based chemical compounds and nanomaterials.

Lanthanides with Unusually Low Oxidation States in the PrB3- and PrB4- Boride Clusters.

Lanthanide elements typically exhibit a +III oxidation state (OS) in chemical compounds with a few in +IV or even +V OS. Although lanthanides with +II OS have been observed recently in organometallic compounds, +I OS is extremely rare. Using a joint photoelectron spectroscopy and quantum theoretical study, we have found two low OS lanthanides in doped boron clusters, PrB3- and PrB4-. These two clusters are shown to have planar structures, in which the Pr atom is bonded to the aromatic boron clusters via two Pr-B σ bonds. Chemical bonding and electronic structure analyses reveal that the Pr atom is in a very low OS in the two boride clusters: +II in PrB3- and +I in PrB4-. The current finding suggests that there should exist a whole class of boride complexes featuring rather low-valent lanthanides and expands the frontier of lanthanide chemistry.

Evolution and Expression Divergence of the CYP78A Subfamily Genes in Soybean.

Gene expression divergence is an important evolutionary driving force for the retention of duplicate genes. In this study, we identified three CYP78A subfamily genes in soybean, GmCYP78A70, GmCYP78A57 and GmCYP78A72, which experienced different duplication events. GmCYP78A70 was mainly expressed in leaf tissue and the vegetative phase, whereas GmCYP78A57 was mainly expressed in floral tissue and seed, i.e., the reproductive phase. Expression of GmCYP78A72 could be detected in all the tissues and phases mentioned above. The expression levels of GmCYP78A70 and GmCYP78A57 in different soybean cultivars showed positive correlations with leaf size and 100-seed weight, respectively. The population genetics analysis indicated that the three genes had experienced different selective pressures during domestication and improved breeding of soybean. Deciphering the function of this subfamily of genes may well prove useful to breeders for improving soybean's agronomic traits.

Genome-wide analysis of dirigent gene family in pepper (Capsicum annuum L.) and characterization of CaDIR7 in biotic and abiotic stresses.

The dirigent (DIR and DIR-like) proteins involved in lignification, play a pivotal role against biotic and abiotic stresses in plants. However, no information is available about DIR gene family in pepper (Capsicum annuum L.). In this study, 24 putative dirigent genes (CaDIRs) were identified, their gene structure, genome location, gene duplication and phylogenetic relationship were elucidated. Tissue-specific expression analysis displayed the highest transcription levels in flower, stem and leaf. Some CaDIRs were up-regulated by virulent (CaDIR2, 3, 6, 7, 11, 14, 16, 22 and 23) and avirulent (CaDIR3, 5, 7, 16, 20, 22, 23 and 24) Phytophthora capsici strains, as well as by Methyl jasmonate, salicylic acid, NaCl and mannitol stresses. Acid-soluble lignin content increased (103.21%) after P. capsici inoculation (48-hour). Silencing of CaDIR7 weakened plant defense by reducing (~50%) root activity and made plants more susceptible (35.7%) to P. capsici and NaCl (300 mM). Leaf discs of the CaDIR7:silenced plants exposed to NaCl and mannitol (300 mM each), exhibited a significant decrease (56.25% and 48% respectively) in the chlorophyll content. These results suggested that CaDIR7 is involved in pepper defense response against pathogen and abiotic stresses and the study will provide basic insights for future research regarding CaDIRs.

Nb2©Au6: a molecular wheel with a short Nb[triple bond, length as m-dash]Nb triple bond coordinated by an Au6 ring and reinforced by σ aromaticity.

We report a photoelectron spectroscopy and high-resolution photoelectron imaging study of a bimetallic Nb2Au6 - cluster. Theoretical calculations, in conjunction with the experimental data, reveal that Nb2Au6 -/0 possess high-symmetry D 6h structures featuring a Nb-Nb axis coordinated equatorially by an Au6 ring. Chemical bonding analyses show that there are two π bonds and one σ bond in the Nb2 moiety in Nb2©Au6, as well as five totally delocalized σ bonds. The Nb[triple bond, length as m-dash]Nb triple bond is strengthened significantly by the delocalized σ bonds, resulting in an extremely short Nb-Nb bond length comparable to the quintuple bond in gaseous Nb2. The totally delocalized σ bonding in Nb2©Au6 is reminiscent of σ aromaticity, representing a new bonding mode in metal-ligand systems. The unusually short Nb-Nb bond length in Nb2©Au6 shows that the Au6 ring can serve as a bridging ligand to facilitate multiple bonding in transition metal dimers via delocalized σ bonding.

Bismuth-Boron Multiple Bonding in BiB2 O- and Bi2 B.

Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB2 O- and Bi2 B- , containing triple and double B-Bi bonds are presented. The BiB2 O- and Bi2 B- clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB2 O- ([Bi≡B-B≡O]- ) and Bi2 B- ([Bi=B=Bi]- ), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding.

PrB7- : A Praseodymium-Doped Boron Cluster with a PrII Center Coordinated by a Doubly Aromatic Planar η7 -B73- Ligand.

The structure and bonding of a Pr-doped boron cluster (PrB7- ) are investigated using photoelectron spectroscopy and quantum chemistry. The adiabatic electron detachment energy of PrB7- is found to be low [1.47(8) eV]. A large energy gap is observed between the first and second detachment features, indicating a highly stable neutral PrB7 . Global minimum searches and comparison between experiment and theory show that PrB7- has a half-sandwich structure with C6v symmetry. Chemical bonding analyses show that PrB7- can be viewed as a PrII [η7 -B73- ] complex with three unpaired electrons, corresponding to a Pr (4f2 6s1 ) open-shell configuration. Upon detachment of the 6s electron, the neutral PrB7 cluster is a highly stable PrIII [η7 -B73- ] complex with Pr in its favorite +3 oxidation state. The B73- ligand is found to be highly stable and doubly aromatic with six delocalized π and six delocalized σ electrons and should exist for a series of lanthanide MIII [η7 -B73- ] complexes.

Observation of a metal-centered B2-Ta@B18- tubular molecular rotor and a perfect Ta@B20- boron drum with the record coordination number of twenty.

A tubular molecular rotor B2-Ta@B18- (1) and boron drum Ta@B20- (2) with the highest coordination number of twenty in chemistry are observed via a joint photoelectron spectroscopy and first-principles theory investigation.