Synergetic utilization of glucose and glycerol for efficient myo-inositol biosynthesis

myo-Inositol (MI) as a dietary supplement can provide various health benefits. One major challenge to its efficient biosynthesis is to achieve proper distribution of carbon flux between growth and production. Herein, this challenge was overcome by synergetic utilization of glucose and glycerol. Specifically, glycerol was catabolized to support cell growth while glucose was conserved as the building block for MI production. Growth and production were coupled via the phosphotransferase system, and both modules were optimized to achieve efficient production. First, the optimal enzyme combination was established for the production module. It was observed that enhancing the production module resulted in both increased MI production and better cell growth. In addition, glucose was shown to inhibit glycerol utilization via carbon catabolite repression and the inhibition was released by over-expressing glycerol kinase. Furthermore, the inducible promoter was replaced by strong constitutive promoters to avoid inducer use. With these efforts, the final strain produced MI with both high titer and yield. In fed-batch cultivation, 76 g/L of MI was produced, showing scale-up potential. This study provides a promising strategy to achieve rational distribution of carbon flux.     

Scarcity-weighted global land and metal footprints

Resource scarcity poses an increasing threat to the supply security of modern economies. Some grand challenges ahead are the limits to agricultural expansion and the geologic scarcity of metals. To better understand the drivers behind land and metal depletion, footprint-type indicators are gaining importance. Such indicators, however, fail to differentiate between vastly different degrees of resource availability across regions. Using crop suitability areas and metal reserve base data, we calculate scarcity-weighted land and metal footprints for the major economies with the EXIOBASE global multi-regional input-output model. Scarcity-weighting causes a significant reordering of the global rankings of countries for both land and metal footprints. Land scarcity focuses mostly on cereals (∼54% from the total agricultural land used) and oil crops (∼15%), the former being notably affected by water scarcity issues in Asia and the Middle East. Metal scarcity focuses on copper ores (∼69%) and iron (∼11%), the former being a globally scarce metal impacting multiple economies. The large impact of scarcity-weighting suggests that, while non-weighted resource footprints are a valid proxy of resource use, these are not always aligned with further implications of resource depletion and supply security. In this sense, scarcity-weighting can offer an initial overview of those countries where analyses at finer scales may be more valuable. Our results also show that international trade is a major driver of land and metal depletion in some developing regions. This highlights the intersection of environmental justice and globalization, as the burden of resource depletion often falls into poorer regions which critically rely on exports.     

Design,synthesis and biological evaluation of HIV-1 protease inhibitors with morpholine derivatives as P2 ligands in combination with cyclopropyl as P1′ ligand

A series of novel HIV-1 protease inhibitors has been designed and synthesized, which contained morpholine derivatives as the P2 ligands and hydrophobic cyclopropyl as the P1′ ligand at the meantime in this study, with the aim of improving the interactions between the active sites of HIV-1 protease and the inhibitors. Twenty-eight compounds were synthesized and assessed, among which inhibitors m18 and m1 exhibited excellent inhibitory effect on the activity of HIV-1 protease with IC₅₀ value of 47 nM and 53 nM, respectively. The molecular modeling of m1 revealed possible hydrogen bondings or van der Waals between the inhibitor and the protease, worthy of in-depth study.     

Co-transfer of two plasmids determining bacteriocin production and sucrose utilization in Streptococcus faecium

Abstract Streptococcus faecium strain 25 produced a bacteriocin (enterococcin Sf25), metabolized sucrose and contained three plasmids of 2.4, 4.7 and 13.0 MDa. Plasmids Sfp2.4 and Sfp4.7 were cotransferred in a filter mating procedure to sucrose negative and bacteriocin negative S. faecium strain M16. Strain M16 harboured a nonselftransferable plasmid Sfp 19.1 MDa, which was responsible for erythromycin resistance. Transcipient cells of S. faecium M16 contained the 19.1-MDa plasmid and plasmids Sfp2.4 and Sfp4.7, produced the enterococcin Sf25 and gained the ability to degrade sucrose.     

Studies on the population dynamics of the assassin bug,Agriosphodrus dohrni Signoret,in relation to resting site utilization

Population Ecology -     

Seed quality effects in bulb onions (Allium cepa L.)

The nature and persistence of seed quality effects produced by a range of seed production treatments was investigated in the autumn-sown onion crop. Genotypically equivalent seed lots raised in different glasshouses within the same year were found to germinate at significantly different rates. The seed lot which emerged earlier produced larger seedlings and this difference in size persisted throughout the growing period. In a comparison between the effects of hand crossing and self-pollination techniques the hand crossing method produced a much lower total seed yield but heavier seeds and larger plants. The induced effects persisted throughout the year but were not significant in the mature bulb characters. The implications of these results upon the control of seed production for plant breeding and genetical experiments is discussed.     

Studien über die endokrinen Zellen des Magendarmtraktes

Zusammenfassung Die serotoninhaltigen, nach Formaldehydbedampfung im UV-Licht gelbfluoreszierenden EC-Zellen im Magendarmepithel wurden bei normalen und bei tryptophanfrei ernährten Ratten untersucht. Bei Kontrolltieren ist die Zahl der EC-Zellen, bezogen auf die Schleimhautfläche, im Duodenum größer als im Pylorus. Im Duodenum sind die EC-Zellen etwa gleichmäßig auf Oberflächen- und Drüsenepithel verteilt, im Pylorus ganz überwiegend im Drüsenepithel lokalisiert. Die Brunnerschen Drüsen besitzen keine EC-Zellen. Tryptophanfreie Diät führt zu starker Abnahme des Serotoningehalts der EC-Zellen, nach Umsetzung auf Normalkost steigt er wieder an. — Die Ergebnisse sprechen weiterhin dafür, daß die EC-Zelle sowohl Speicher- als auch Syntheseort von Serotonin ist. Dabei kommt Serotonin in der EC-Zelle wahrscheinlich in zwei Fraktionen vor, nämlich zytoplasmatisch gelöst und granulagebunden. Die histochemischen Nachweismethoden für Serotonin, Möglichkeiten des Eingriffs in die verschiedenen Syntheseschritte des Serotonins und deren Spezifität in bezug auf die EC-Zelle als physiologischem Ort der Serotoninsynthese werden diskutiert.

---

Studies on the endocrine cells of the gastrointestinal tractII. Fluorescence microscopy of the EC-cells after tryptophan-free diet

Summary The serotonin-containing EC-cells of the gastro-intestinal mucosa, which show yellow fluorescence after treatment with gaseous formaldehyde, were investigated in the rat after normal and tryptophan-free nourishment. In control animals the number of EC-cells, related to epithelium area is higher in the duodenum than in the pyloric region. In the duodenum the EC-cells show about the same distribution in surface epithelium and gland epithelium. In the pyloric region EC-cells are localized predominantly in the gland epithelium. No EC-cells were found in the Brunner glands. After tryptophan-free diet the serotonin-level of the EC-cells strongly decreases; serotonin-level increases after return to normal nourishment. The results also suggest, that serotonin is synthesized as well as stored in the EC-cell and that it occurs in two fractions: bound to granules and dissolved in the cytoplasm. Discussion deals with the histochemical methods for determination of serotonin, the possibilities of influencing the pathways of serotonin metabolism and the specificity of these possibilities concerning the EC-cell as the physiological site of serotonin synthesis.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft, Antrag Fo 77, 1–4.     

Sizes of granular vesicles in the rat median eminence,with special reference to the zona granulosa

Summary A quantitative evaluation has been made of the sizes of neuronal granular vesicles (GV) in different (sub-)zones of the rat median eminence. On the basis of the frequency distribution of the mean sizes of the GV in the individual nerve profiles, at least 4 tentative categories of nerve profiles may be distinguished. However, available data do not permit characterization of nerve fibre categories in terms of neurohormone and/or neurotransmitter storage. From dorsal to ventral the palisade zone shows a decrease in mean size of GV; furthermore, the relative number of nerve profiles characterized by small GV (mean size smaller than 112 nm) increases. In contrast, the GV in the zona granulosa, that part of the external zone of the median eminence ventral to the palisade zone, are of relatively large size. Qualitative observations indicate that the zona granulosa may be regarded as an area for both storage and release of biologically active substances. We are grateful to Mrs. R.M.Y. Hartsteen for technical assistance, to Miss P.C. Delfos and Mr. W. van den Oudenalder for photographic assistance and to Prof. J. Moll for helpful criticism.