Mannose metabolism in corn and its impact on leaf metabolites, photosynthetic gas exchange, and chlorophyll fluorescence

When intact corn leaves were provided millimolar concentrations of d-mannose through the transpiration stream photosynthesis was inhibited; 5.7 millimolar resulted in a 50% inhibition of the carbon exchange rate. This inhibition was partially reversible by the addition of orthophosphate to the feeding solution. Mannose metabolism by corn leaves was limited in that it did not act as a resource for sucrose or starch synthesis. Mannose 6-phosphate accumulated in the leaf tissues and was slowly metabolized by a pathway involving mannose 1-phosphate. Correlated with the mannose-6-phosphate accumulation were decreases in ATP, orthophosphate, sucrose, and phosphoenolpyruvate and increases in starch and maltose. When provided in the transpiration stream mannose had access to both mesophyll and bundle sheath cells. Mannose feeding led to oscillations in steady state chlorophyll fluorescence emission (680 nanometers) and an elimination of the Kautsky effect during fluorescence induction. Pyridoxal 5-phosphate and 2,4-dinitrophenol were found to be inhibitors of CO₂ exchange when provided in the transpiration stream of intact corn leaves. However, Pyridoxal 5-phosphate induced a quenching of steady state fluorescence while 2,4-dinitrophenol led to an increase in fluorescence emission.     

EVIDENCE FOR CYTOPLASMIC DNA IN ROOT CELLS OF NICOTIANA

Sterile root cultures from Nicotiana tabacum were grown with H³-thymidine added to the medium for various intervals. Incorporation of the labeled nucleoside into nuclear DNA occurred in a fraction of the nuclei which increased with time. In addition, the cytoplasm of all cells incorporated enough tritium to be readily detected by autoradiography. The tritium was not removed by hydrolysis in 1 N HCl at 60°C for 10 minutes, but was removed by digestion in a DNase solution which also removed nuclear DNA. The amount of tritium in the cytoplasm increased during the first 2 hours, but did not appear to increase significantly during the following 5 hours. If the roots were transferred to unlabeled medium after 2 hours, the label was diluted faster than expected by growth without turnover of the labeled component. If FUdR was added to the unlabeled medium, the depletion occurred faster during the first 6 hours, but later appeared to level off so that at 10 hours these cultures did not differ from those incubated without FUdR. However, the addition of an excess of unlabeled carrier had no effect on the rate of depletion of the cytoplasmic label. Actinomycin D, which inhibited the incorporation of H³-cytidine into RNA in the root tips, had no effect on the incorporation of H³-thymidine into the cytoplasmic component. However, Mitomycin C or a high concentration of deoxyadenosine inhibited the incorporation of H³-thymidine into the cytoplasmic component as well as into the nuclear DNA. It is concluded that H³-thymidine is incorporated into a cytoplasmic fraction which has the characteristics of DNA, with a measurable rate of turnover. This fraction is synthesized regardless of whether or not the nucleus is synthesizing DNA. Although the function of cytoplasmic fraction is not yet known, it does not appear to be that of supplying precursors for the synthesis of the nuclear DNA.     

New Class of Ni‐Rich Cathode Materials Li[NixCoyB1−x−y]O2 for Next Lithium Batteries

A new class of layered cathodes, Li[Ni_xCo_yB_1?x?y]O₂ (NCB), is synthesized. The proposed NCB cathodes have a unique microstructure in which elongated primary particles are tightly packed into spherical secondary particles. The cathodes also exhibit a strong crystallographic texture in which the a–b layer planes are aligned along the radial direction, facilitating Li migration. The microstructure, which effectively suppresses the formation of microcracks, improves the cycling stability of the NCB cathodes. The NCB cathode with 1.5 mol% B delivers a discharge capacity of 234 mAh g^?1 at 0.1 C and retains 91.2% of its initial capacity after 100 cycles (compared to values of 229 mAh g^?1 at 0.1 C and 78.8% for pristine Li[Ni_0.9Co_0.1]O₂). This study shows the importance of controlling the microstructure to obtain the required cycling stability, especially for Ni‐rich layered cathodes, where the main cause of capacity fading is related to mechanical strain in their charged state.     

Flower model traps reduced thrips infestations on a pepper crop in field

A flower model trap developed by modifying an artificial yellow chrysanthemum flower was more attractive to flower thrips than commercial yellow sticky traps. Installation of these flower model traps (20 traps per 50 m² plot) was reported to reduce seasonal populations of Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) on strawberry flowers in greenhouses. In this study, we sought to determine if the installation of such flower model traps would reduce thrips populations in a pepper field. The traps were installed at the bottom of the plant canopy at varying densities (0, 5, 10, and 20 traps) in 20 plots (each 3 × 5 m²) using a completely randomized design. Thrips populations on pepper flowers were sampled from 1 to 29 July in 2009. All thrips sampled on the flowers were identified as F. intonsa. A significant effect of treatment and sampling date was found from repeated-measure analysis of variance. The highest density (20 traps per 15 m²) of traps significantly reduced the female and male F. intonsa population compared to the control by 61 and 49%, respectively. However, no difference in immature thrips numbers was found among the treatments. These results indicate that this flower model trap can be a useful tool for the management of flower thrips on field-grown peppers.     

Metabolic engineering of Escherichia coli for enhanced biosynthesis of poly(3-hydroxybutyrate) based on proteome analysis

We have previously analyzed the proteome of recombinant Escherichia coli producing poly(3-hydroxybutyrate) [P(3HB)] and revealed that the expression level of several enzymes in central metabolism are proportional to the amount of P(3HB) accumulated in the cells. Based on these results, the amplification effects of triosephosphate isomerase (TpiA) and fructose-bisphosphate aldolase (FbaA) on P(3HB) synthesis were examined in recombinant E. coli W3110, XL1-Blue, and W lacI mutant strains using glucose, sucrose and xylose as carbon sources. Amplification of TpiA and FbaA significantly increased the P(3HB) contents and concentrations in the three E. coli strains. TpiA amplification in E. coli XL1-Blue lacI increased P(3HB) from 0.4 to 1.6 to g/l from glucose. Thus amplification of glycolytic pathway enzymes is a good strategy for efficient production of P(3HB) by allowing increased glycolytic pathway flux to make more acetyl-CoA available for P(3HB) biosynthesis.     

Compositionally Graded Cathode Material with Long‐Term Cycling Stability for Electric Vehicles Application

Al is introduced into a compositionally graded cathode with average composition of Li[Ni_0.61Co_0.12Mn_0.27]O₂ (FCG61) whose Ni and Mn concentrations are designed to vary continuously within the cathode particle. The Al‐substituted full concentration gradient (Al‐FCG61) cathode is tested for 3000 cycles in a full‐cell, mainly to gauge its viability for daily charge/discharge cycles during the service life of electric vehicles (≈10 years). The Al‐substitution enables the Al‐FCG61 cathode to maintain 84% of its initial capacity even after 3000 cycles. It is demonstrated that the Al‐substitution strengthens the grain boundaries, substantiated by the mechanical strength data, thereby delaying the nucleation of microcracks at the phase boundaries which is shown to be the main reason for the cathode failure during long‐term cycling. It also shows that the Al‐substitution decreases the cation mixing and suppresses the deleterious formation of the secondary phase that likely initiates the microcracks. Unlike an NCA cathode, whose depth of discharge (DOD) must be limited to 60% for long‐term cycling, the proposed Al‐FCG61 cathode is cycled at 100% DOD for 3000 cycles to fully utilize its available capacity for maximum energy density and subsequent reduction in cost of the battery.     

An integrated analysis to predict micro‐RNAs targeting both stemness and metastasis in breast cancer stem cells

Several evidences support the idea that a small population of tumour cells representing self‐renewal potential are involved in initiation, maintenance, metastasis, and outcomes of cancer therapy. Elucidation of microRNAs/genes regulatory networks activated in cancer stem cells (CSCs) is necessary for the identification of new targets for cancer therapy. The aim of the present study was to predict the miRNAs pattern, which can target both metastasis and self‐renewal pathways using integration of literature and data mining. For this purpose, mammospheres derived from MCF‐7, MDA‐MB231, and MDA‐MB468 were used as breast CSCs model. They had higher migration, invasion, and colony formation potential, with increasing in stemness‐ and EMT‐related genes expression. Our results determined that miR‐204, ‐200c, ‐34a, and ‐10b contemporarily could target both self‐renewal and EMT pathways. This core regulatory of miRNAs could increase the survival rate of breast invasive carcinoma via up‐regulation of OCT4, SOX2, KLF4, c‐MYC, NOTCH1, SNAI1, ZEB1, and CDH2 and down‐regulation of CDH1. The majority of those target genes were involved in the regulation of pluripotency, MAPK, WNT, Hedgehog, p53, and transforming growth factor β pathways. Hence, this study provides novel insights for targeting core regulatory of miRNAs in breast CSCs to target both self‐renewal and metastasis potential and eradication of breast cancer.