Syntheses And Photo-Reactivity Of Chromene Natural Products And Photo-degradation of Steroidal Hormones

AbstractOver the past twenty years natural products from Piper, a tropical genus of plant, have been extensively studied due to the number of biologically active natural products with unique structures. The genus Piper provides an excellent model system for exploring the relationship between natural product diversity and its impact on biotic interactions. Our group has isolated three prenylated benzoic acid derivatives, 36-38, from Piper kelleyi Tepe, a newly described species of Piper that grow in the Eastern Andes of Ecuador and Peru. These unique natural products have recently been found to significantly vary in their relative concentration and this variation was found to be a main driver of diversification of associated herbivores specifically feeding on P. kelleyi. Phytochemical variation was found to be associated with elevation, Chapters 3 of this dissertation describes our exploration of the unique photochemistry.Our biosynthetic hypothesis suggests that these three metabolites share a common pathway, where one is the precursor to the other. Recent studies unveiled that these metabolites varied significantly between individuals and that plants growing at higher elevation were chemically distinct, producing a higher concentration of all three metabolites. Given that the UV-B concentration is established to increase 15%/1,000m of elevation at the equator and the extreme phototoxicity of these metabolites to generalist herbivores, we proposed that a photochromic process involving the chromene metabolite could be driving both the phytochemical variation and the associated toxicity of the metabolites. Studies of this photochromism in the context of the natural products variation and toxicity were conducted and are the subject in chapter 2 & 3.The photochemistry of environmental contaminants, especially agricultural pharmaceuticals, has been largely understudied. While it is widely accepted that photochemical degradation of these contaminants is a primary mode of environmental clearing, reversible photochemical transformations that provide selective avenues could result in long-lived environmental contaminants and can also provide reactive pathways that produce contaminants with enhanced biological activity. Trenbolone acetate (TBA) is an anabolic steroid injected to beef cattle for muscle growth, and trace amounts of TBA leach from their manure into our aquatic systems. Risk from this contamination is eliminated as TBA rapidly photodegrades in the exposure of sunlight. Unfortunately, at night TBA regenerates causing potential risk to aquatic organisms. We have recently extended this study to understand the aquatic photochemistry of dienogest (DIE), a potent progestin analog that has structural similarities to TBA. My study demonstrates that DIE rapidly photodegrades under exposed light and reverts to dienogest when left in the dark. Additionally, we have found that continued irradiation of dienogest produces a major photoproduct that contains an aromatic A ring, like estrogen

Vietnam Inbound M&A Activity: the Role of Government Policy and Regulatory Environment

With a robust recent history of reform and opening, joining of the World Trade Organization, and negotiating a myriad of regional and global trade agreements, Vietnam has emerged as a promising destination for foreign direct investment(FDI) and cross-border mergers and acquisitions (M&A). In this paper, we providean overview of Vietnam’s inbound mergers and acquisitions and review the twomain driving forces of inbound M&A, which are the legal framework reformprocess and the equitization of State-owned enterprises. We close by providingdirections for future research in the area of cross-border M&As

Co-doping red-emitting Sr2Si5N8:Eu2+ into yellow-emitting phosphor-packaging for enhancing the optical properties of the 8500 K remote-phosphor packaging wleds

In the last decades, WLEDs attract more and more consideration in both academic and industrial purposes because of its advantages such as fast response time, environment friendliness, small size, long lifetime, and high efficiency. In this research, by doping the red-emitting Sr2Si5N8:Eu2+ phosphor particles into yellow-emitting YAG:Ce phosphor-packaging, a new recommendation for enhancing the optical properties (color uniformity, color rendering index, and lumen output) of the 8500 K remote-phosphor packaging WLEDs is presented, investigated, and demonstrated. By using Mat Lab and Light Tools software based on Mie Theory, the obtained results show that the optical properties of the 8500 K remote-phosphor packaging WLEDs significantly depended on Sr2Si5N8:Eu2+ concentration. The results have provided a potential practical recommendation for manufacturing remote-phosphor W-LEDs.Web of Science1341034102

How is wine produced?

7 p.Wine making has been around for thousands of years and has been interpreted and molded into an art. There are five components, or steps to making wine: harvesting, crushing and pressing, fermentation, clarification, and aging and bottling. Undoubtedly, one can find endless deviations and clarifications along the way (“Wine making process”). All of these steps result into personal preference and in the end it’s all about pleasing the palette

An Early Reduction in Treg Cells Correlates with Enhanced Local Inflammation in Cutaneous Leishmaniasis in CCR6-Deficient Mice

Resistance to Leishmania major infection is dependent on the development of a cell-mediated Th1 immune response in resistant C57BL/6 mice whereas Th2-prone BALB/c mice develop non-healing lesions after infection. The chemokine receptor CCR6 is shared by anti-inflammatory regulatory T cells and pro-inflammatory Th17 cells. In a recent study we showed that C57BL/6 mice deficient in CCR6 exhibited enhanced footpad swelling and impaired T helper cell migration indicated by reduced recruitment of total T helper cells into the skin after infection and a reduced delayed type hypersensitivity reaction. Based on these findings we tested whether the lack of CCR6 alters Treg or Th17 cell responses during the course of Leishmania major infection. When we analyzed T cell subsets in the lymph nodes of CCR6-deficient mice, Th17 cell numbers were not different. However, reduced numbers of Treg cells paralleled with a stronger IFNγ response. Furthermore, the early increase in IFNγ-producing cells correlated with increased local tissue inflammation at later time points. Our data indicate an important role of CCR6 for Treg cells and a redundant role for Th17 cells in a Th1 cell-driven anti-parasitic immune response against Leishmania major parasites in resistant C57BL/6 mice

Diversity and Activity of Microbial Extracellular Peptidases in Soil

Soil nitrogen exists largely as organic matter, including plant liter, dead animal matter, and microbial necromass. About 90% of soil organic nitrogen is proteinaceous material that is too large for plants and microorganisms to assimilate directly. Protein depolymerization therefore plays a critical role in mobilizing this organic source of nitrogen, producing lower molecular weight molecules that are bioavailable for both microorganisms and plants. The decomposition of proteins in soils serves as the rate-limiting step of the nitrogen cycle. The ability of microorganisms to access and break down proteinaceous material depends largely on their production of extracellular peptidases, but it involves a trade-off with the energetic cost of producing and secreting these enzymes into the environment, including the risk that other microorganisms can compete with the peptidase-producing organisms for the products released through depolymerization. Consequently, in order to optimize this energy investment, there might be a tight connection between soil environmental conditions and microbial proteolytic activity. Despite its ecological importance, there is a lack of understanding about the diversity of these extracellular peptidases and their activity as an important factor influencing the protein degradability in soils. In this dissertation, I first assessed the genetic potential for microorganisms to produce extracellular enzymes, and second, I developed and applied a novel approach to measure the activities of different classes of peptidases in soil. In my first two chapters, I evaluated the abundance and diversity of microbial extracellular peptidases, their evolutionary conservation, and distribution as a function of environmental habitat and lifestyle. Chapter 2 focuses on the secreted peptidases of prokaryotes (Archaea, Bacteria); chapter 3 focuses on Fungi, the dominant soil eukaryote. In both chapters, I analyzed secreted peptidases across microbial lineages using their genomic information and corresponding annotated protein sequences assembled from several databases, including MEROPS, Silva, JGI Genome Portal, and MycoCosm. Peptidase gene sequences of 147 archaeal, 2,191 bacterial and 612 fungal genomes were screened for secretion signals, resulting in 55,072 prokaryotic and 31,668 eukaryotic genes coding for secreted peptidases. I found that Archaea, Bacteria, and Fungi possess unique complements of secreted peptidases and there are differences in the number of secreted peptidases per genome, indicating potential differential abilities for organic nitrogen acquisition. The majority of secreted peptidase families not only follow the phylogenetic evolutionary distribution, but also segregate based on the microbial lifestyles and microbial habitats. This suggests that microorganisms optimize their secreted peptidases to match their surrounding environments. In Chapter 4, I incorporated the use of selective inhibitors to block the activity of different classes of peptidases. I designed a protocol with these peptidase inhibitors to use directly in natural soils. I validated and optimized this protocol with pure enzymes and peptidase-supplemented soils. This research revealed that the profile of extracellular peptidase activities belonging to different catalytic types varies among soils and correlates with both soil chemical and microbial properties. This is in line with our assumption that soil microorganisms respond to their environmental conditions by investing in peptidases that can optimize their activity. Collectively, this work provides a comprehensive and foundational understanding about the contribution of different catalytic types of microbial extracellular peptidases to organic nitrogen turnover in soils

How swelling debts give rise to a new type of politics in Vietnam

Vietnam has seen fast-rising debts, both domestic and external, in recent years. This paperreviews the literature on credit market in Vietnam, providing an up-to-date take on the domesticlending and borrowing landscape. The study highlights the strong demand for credit in both therural and urban areas, the ubiquity of informal lenders, the recent popularity of consumer financecompanies, as well as the government’s attempts to rein in its swelling public debt. Given thehigh level of borrowing, which is fueled by consumerism and geopolitics, it is inevitable that theamount of debt will soon be higher than the saving of the borrowers. Unlike the conventional wisdom that creditors have more bargaining power over the borrowers, we suggest that—albeitlacking a quantitative estimation—when the debts pile up so high that the borrowers could not repay, the power dynamics may reverse. In this new politics of debt, the lenders fear to lose the money's worth and continue to lend and feed the insolvent debtors. The result is a toxic lending/borrowing market and profound lessons, from which the developing world could learn