Initiation of cytosolic plant purine nucleotide catabolism involves a monospecific xanthosine monophosphate phosphatase

In plants, guanosine monophosphate (GMP) is synthesized from adenosine monophosphate via inosine monophosphate and xanthosine monophosphate (XMP) in the cytosol. It has been shown recently that the catabolic route for adenylate-derived nucleotides bifurcates at XMP from this biosynthetic route. Dephosphorylation of XMP and GMP by as yet unknown phosphatases can initiate cytosolic purine nucleotide catabolism. Here we show that Arabidopsis thaliana possesses a highly XMP-specific phosphatase (XMPP) which is conserved in vascular plants. We demonstrate that XMPP catalyzes the irreversible entry reaction of adenylate-derived nucleotides into purine nucleotide catabolism in vivo, whereas the guanylates enter catabolism via an unidentified GMP phosphatase and guanosine deaminase which are important to maintain purine nucleotide homeostasis. We also present a crystal structure and mutational analysis of XMPP providing a rationale for its exceptionally high substrate specificity, which is likely required for the efficient catalysis of the very small XMP pool in vivo.

Strategy for Rapid Recovery of Simultaneous Sulfide and Nitrite Removal under High Substrate Inhibition

The paper deals with the strategy for a quick recovery of reactor treating sulfide and nitrite simultaneously under inhibition caused by high substrate concentration. For influent sulfide concentration of 360 mg S/L, respective sulfide and nitrite removal percentages dropped to 74.19% and 14.33% due to inhibition caused by high sulfide and nitrite concentrations. It was found that reduction in the influent substrate concentration (300 mg S/L) could not revive the nitrite removal performance in 4 days’ operation, which still showed a declining tendency from 47.16–18.52%. Regulating the influent pH around 6.70 ± 0.10, it only took 4 days to recover the performance for 300 mg S/L. Furthermore, at influent sulfide concentration increased to 360 mg S/L, respective sulfide and nitrite removal percentages were 99.76 ± 0.27% and 100%. The strategy of regulating influent pH could recover the process performance in a short term, which would provide great convenience for subsequent process research.

Direct Cross-Coupling of Alcohols with O-Nucleophiles Mediated by N-Iodosuccinimide as a Precatalyst under Mild Reaction Conditions

We report N-iodosuccinimide as the most efficient and selective precatalyst among the N-halosuccinimides for dehydrative O-alkylation reactions between various alcohols under high-substrate concentration reaction conditions. The protocol is non-metal, one-pot, selective, and easily scalable, with excellent yields; enhancing the green chemical profiles of these transformations.

From Propagation to Field: Influence of Tray Design on Tree Seedling Quality and Performance1

This study evaluated the effects of low, moderate and high substrate exposure air-pruning propagation trays on eastern cottonwood (Populus deltoides W. Bartram ex Marshall ssp. deltoides) and black cherry (Prunus serotina Ehrh.) seedling root system quality and overall performance. Root system quality was characterized primarily by proportion of coarse root defects within the container imprint. Seedlings were evaluated after a nearly four-month commercial greenhouse production phase and one year after transplanting into a nursery field. Above and below-ground growth were measured at both time points. Proportions of coarse root defects, indicating degree of root deflection in container production, were persistent between greenhouse and field production phases. The Open (high substrate exposure) tray produced seedlings with roughly three times less deflected coarse root weight compared to the Closed Wall (low substrate exposure) tray for both species in both production phases. At neither production phase were there significant differences in above-ground growth among trays. This corroborates findings from other research studies that have found that variable root system quality does not always result in above-ground growth differences; and that when it does, differences in growth may take several years to manifest. Index words:, tree seedling quality, root defects, transplant performance, above-ground growth. Species used in this study: eastern cottonwood (Populus deltoides W. Bartram ex Marshall ssp. deltoides), black cherry (Prunus serotina Ehrh.).

Fabrication, micro-structure characteristics and transport properties of co-evaporated thin films of Bi2Te3 on AlN coated stainless steel foils

N-type bismuth telluride (Bi2Te3) thin films were prepared on an aluminum nitride (AlN)-coated stainless steel foil substrate to obtain optimal thermoelectric performance. The thermal co-evaporation method was adopted so that we could vary the thin film composition, enabling us to investigate the relationship between the film composition, microstructure, crystal preferred orientation and thermoelectric properties. The influence of the substrate temperature was also investigated by synthesizing two sets of thin film samples; in one set the substrate was kept at room temperature (RT) while in the other set the substrate was maintained at a high temperature, of 300 °C, during deposition. The samples deposited at RT were amorphous in the as-deposited state and therefore were annealed at 280 °C to promote crystallization and phase development. The electrical resistivity and Seebeck coefficient were measured and the results were interpreted. Both the transport properties and crystal structure were observed to be strongly affected by non-stoichiometry and the choice of substrate temperature. We observed columnar microstructures with hexagonal grains and a multi-oriented crystal structure for the thin films deposited at high substrate temperatures, whereas highly (00 l) textured thin films with columns consisting of in-plane layers were fabricated from the stoichiometric annealed thin film samples originally synthesized at RT. Special emphasis was placed on examining the nature of tellurium (Te) atom based structural defects and their influence on thin film properties. We report maximum power factor (PF) of 1.35 mW/m K2 for near-stoichiometric film deposited at high substrate temperature, which was the highest among all studied cases.

Optimization of the Acetification Stage in the Production of Wine Vinegar by Use of Two Serial Bioreactors

In the scope of a broader study about wine acetification, previous works concluded that using a single bioreactor hindered simultaneously reaching high productivities with high substrate consumption and the use of two serially arranged bioreactors (TSAB) could achieve such goal. Then, the aim of this work is the optimization, using Karush–Kuhn–Tucker (KKT) conditions, of this TSAB using polynomial models previously obtained. The ranges for the operational variables leading to either maximum and minimum mean rate of acetification of 0.11 ≤ (rA)global ≤ 0.27 g acetic acid·(100 mL·h)−1 and acetic acid production of 14.7 ≤ Pm ≤ 36.6 g acetic acid·h−1 were identified; the results show that simultaneously maximizing (rA)global and Pm is not possible so, depending on the specific objective, different operational ranges must be used. Additionally, it is possible to reach a productivity close to the maximum one (34.6 ≤ Pm ≤ 35.5 g acetic acid·h−1) with an almost complete substrate use [0.2% ≤ Eu2 ≤ 1.5% (v/v)]. Finally, comparing the performance of the bioreactors operating in series and in parallel revealed that the former choice resulted in greater production.