Vanadyl bisacetylacetonate protects β cells from palmitate-induced cell death through the unfolded protein response pathway

Endoplasmic reticulum (ER) stress induced by free fatty acids (FFA) is important to β-cell loss during the development of type 2 diabetes. To test whether vanadium compounds could influence ER stress and the responses in their mechanism of antidiabetic effects, we investigated the effects and the mechanism of vanadyl bisacetylacetonate [VO(acac)₂] on β cells upon treatment with palmitate, a typical saturated FFA. The experimental results showed that VO(acac)₂ could enhance FFA-induced signaling pathways of unfolded protein responses by upregulating the prosurvival chaperone immunoglobulin heavy-chain binding protein/78-kDa glucose-regulated protein and downregulating the expression of apoptotic C/EBP homologous protein, and consequently the reduction of insulin synthesis. VO(acac)₂ also ameliorated FFA-disturbed Ca²⁺ homeostasis in β cells. Overall, VO(acac)₂ enhanced stress adaption, thus protecting β cells from palmitate-induced apoptosis. This study provides some new insights into the mechanisms of antidiabetic vanadium compounds.     

Genome-Wide Identification, Classification, and Expression Analysis of Autophagy-Associated Gene Homologues in Rice (Oryza sativa L.)

Autophagy is an intracellular degradation process for recycling macromolecules and organelles. It plays important roles in plant development and in response to nutritional demand, stress, and senescence. Organisms from yeast to plants contain many autophagy-associated genes (ATG). In this study, we found that a total of 33 ATG homologues exist in the rice [Oryza sativa L. (Os)] genome, which were classified into 13 ATG subfamilies. Six of them are alternatively spliced genes. Evolutional analysis showed that expansion of 10 OsATG homologues occurred via segmental duplication events and that the occurrence of these OsATG homologues within each subfamily was asynchronous. The Ka/Ks ratios suggested purifying selection for four duplicated OsATG homologues and positive selection for two. Calculating the dates of the duplication events indicated that all duplication events might have occurred after the origin of the grasses, from 21.43 to 66.77 million years ago. Semi-quantitative RT–PCR analysis and mining the digital expression database of rice showed that all 33 OsATG homologues could be detected in at least one cell type of the various tissues under normal or stress growth conditions, but their expression was tightly regulated. The 10 duplicated genes showed expression divergence. The expression of most OsATG homologues was regulated by at least one treatment, including hormones, abiotic and biotic stresses, and nutrient limitation. The identification of OsATG homologues showing constitutive expression or responses to environmental stimuli provides new insights for in-depth characterization of selected genes of importance in rice.     

The effect of calciums on molecular motions of proteinase K

The native serine protease proteinase K binds two calcium cations. It has been reported that Ca²⁺ removal decreased the enzyme’s thermal stability and to some extent the substrate affinity, but has discrepant effects on catalytic activity of the enzyme. Molecular dynamics simulations were performed on the Ca²⁺-bound and Ca²⁺-free proteases to investigate the mechanism by which the calciums affect the structural stability, molecular motions, and catalytic activity of proteinase K. Very similar structural properties were observed between these two forms of proteinase K during simulations; and several long-lived hydrogen bonds and salt bridges common to both forms of proteinase K were found to be crucial in maintaining the local conformations around these two Ca²⁺ sites. Although Ca²⁺ removal enhanced the overall flexibility of proteinase K, the flexibility in a limited number of segments surrounding the substrate-binding pockets decreased. The largest differences in the equilibrium structures of the two simulations indicate that, upon the removal of Ca²⁺, the large concerted motion originating from the Ca1 site can transmit to the substrate-binding regions but not to the catalytic triad residues. In conjunction with the large overlap of the essential subspaces between the two simulations, these results not only provide insight into the dynamics of the underlying molecular mechanism responsible for the unchanged enzymatic activity as well as the decreased thermal stability and substrate affinity of proteinase K upon Ca²⁺ removal, but also complement the experimentally determined structural and biochemical data.     

A Durable Alternative for Proton‐Exchange Membranes: Sulfonated Poly(Benzoxazole Thioether Sulfone)s

To develop a durable proton‐exchange membrane (PEM) for fuel‐cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s ( SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid–base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier‐transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy (¹H NMR and ¹⁹F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three‐electrode cell configuration. The physicochemical properties of the membranes vital to fuel‐cell performance are also carefully evaluated under conditions relevant to fuel‐cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25°C to 90°C and excellent thermal stability up to 250°C. Upon elimination of unstable end groups, the co‐polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO‐HFB‐60 (HFB‐60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel‐cell performance to that of an NRE 212 membrane at 80°C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel‐cell applications.     

Efficiency Boost in All-Small-Molecule Organic Solar Cells: Insights from the Re-Ordering Kinetics

Achieving high-performance in all-small-molecule organic solar cells (ASM-OSCs) significantly relies on precise nanoscale phase separation through domain size manipulation in the active layer. Nonetheless, for ASM-OSC systems, forging a clear connection between the tuning of domain size and the intricacies of phase separation proves to be a formidable challenge. This study investigates the intricate interplay between domain size adjustment and the creation of optimal phase separation morphology, crucial for ASM-OSCs’ performance. It is demonstrated that exceptional phase separation in ASM-OSCs’ active layer is achieved by meticulously controlling the continuity and uniformity of domains via re-packing process. A series of halogen-substituted solvents (Fluorobenzene, Chlorobenzene, Bromobenzene, and Iodobenzene) is adopted to tune the re-packing kinetics, the ASM-OSCs treated with CB exhibited an impressive 16.2% power conversion efficiency (PCE). The PCE enhancement can be attributed to the gradual crystallization process, promoting a smoothly interconnected and uniformly distributed domain size. This, in turn, leads to a favorable phase separation morphology, enhanced charge transfer, extended carrier lifetime, and consequently, reduced recombination of free charges. The findings emphasize the pivotal role of re-packing kinetics in achieving optimal phase separation in ASM-OSCs, offering valuable insights for designing high-performance ASM-OSCs fabrication strategies.     

Evaluation of the predatory mite Amblyseius hainanensis (Acari: Phytoseiidae) and artificial rainfall for the management of Brevipalpus obovatus (Acari: Tenuipalpidae)

Brevipalpus obovatus Donnadieu is an important pest mite on tea plants in South China. In the current study, predatory mites of B. obovatus in the tea gardens of Guangzhou were extensively surveyed. In total, 13 species of predatory mites (four families with seven genera) were recorded. The population proportion of Amblyseius hainanensis Wu et Qian was the highest (68.6?%), followed by that of Anystis baccarum (L.) (8.4?%) and A. theae Wu (6.3?%). The effects of starvation time, habitat size and pest population density on the predatory efficiency of the most dominant species, A. hainanensis, feeding on B. obovatus were assessed. In addition, the effectiveness of artificial rainfall in reducing B. obovatus populations was evaluated. After starvation for 48?h, the predatory efficiency of A. hainanensis was significantly higher than those that had been starved for 24 or 72?h when 30-50 B. obovatus eggs were made available. The predation of A. hainanensis on B. obovatus also increased with increasing prey density. The number of prey attacked by A. hainanensis in a 3.2?cm(2) habitat was significantly higher than in a 6.3?cm(2) habitat. The average predation of A. hainanensis was 31.7 eggs per day when offered 100 B. obovatus eggs on a tea leaf. This decreased to 17.8 eggs per day when four A. hainanensis shared 100 B. obovatus eggs. B. obovatus populations can be reduced by artificial rainfall, with the reduction affected by rainfall intensity. With an intensity of 40?mm in 15?min, 90.2?% mortality of B. obovatus occurred; lower mortalities were recorded (13.3 and 29.8?%) when the intensity was 2 or 4?mm in 15?min. Combination of the predatory mite A. hainanensis and artificial rainfall for the integrated pest management of B. obovatus is discussed.     

Cytological and morphology characteristics of natural microsporogenesis within Camellia oleifera

Camellia oleifera is believed to exhibit a complex intraspecific polyploidy phenomenon. Abnormal microsporogenesis can promote the formation of unreduced gametes in plants and lead to sexual polyploidy, so it is hypothesized that improper meiosis probably results in the formation of natural polyploidy in Camellia oleifera. In this study, based on the cytological observation of meiosis in pollen mother cells (PMCs), we found natural 2n pollen for the first time in Camellia oleifera, which may lead to the formation of natural polyploids by sexual polyploidization. Additionally, abnormal cytological behaviour during meiosis, including univalent chromosomes, extraequatorial chromosomes, early segregation, laggard chromosomes, chromosome stickiness, asynchronous meiosis and deviant cytokinesis (monad, dyads, triads), was observed, which could be the cause of 2n pollen formation. Moreover, we confirmed a relationship among the length–width ratio of flower buds, stylet length and microsporogenesis. This result suggested that we can immediately determine the microsporogenesis stages by phenotypic characteristics, which may be applicable to breeding advanced germplasm in Camellia oleifera.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-01002-5.     

Reconstitution of UDP-galactopyranose mutase with 1-deaza-FAD and 5-deaza-FAD: analysis and mechanistic implications

The galactofuranose moiety found in many surface constituents of microorganisms is derived from UDP-D-galactopyranose (UDP-Galp) via a unique ring contraction reaction catalyzed by a FAD-dependent UDP-Galp mutase. When the enzyme is reduced by sodium dithionite, its catalytic efficiency increases significantly. Since the overall transformation exhibits no net change in the redox state of the parties involved, how the enzyme-bound FAD plays an active role in the reaction mechanism is puzzling. In this paper, we report our study of the catalytic properties of UDP-Galp mutase reconstituted with deaza-FADs. It was found that the mutase reconstituted with FAD or 1-deazaFAD has comparable activity, while that reconstituted with 5-deazaFAD is catalytically inactive. Because 5-deazaFAD is restricted to net two-electron process, yet FAD and 1-deazaFAD can undergo concerted two-electron as well as stepwise one-electron redox reactions, the above results support a radical mechanism for the mutase catalyzed reaction. In addition, the activity of the mutase reconstituted with FAD was found to increase considerably at high pHs. These observations have allowed us to propose a new mechanism involving one-electron transfer from the reduced FAD to an oxocarbenium intermediate generated by C-1 elimination of UDP to give a hexose radical and a flavin semiquinone. Subsequent radical recombination leads to a coenzyme-substrate adduct which may play a central role to facilitate the opening and recyclization of the galactose ring. A deprotonation step, accompanied or followed the electron transfer step, to increase the nucleophilicity of the flavin radical anion may account for the activity enhancement at pH > 8.