Synthesis of \u3cem\u3eN\u3c/em\u3e-Acetyl-ᴅ-quinovosamine in \u3cem\u3eRhizobium etli\u3c/em\u3e CE3 is Completed After Its 4-keto-precursor is Linked to a Carrier Lipid

Bacterial O-antigens are synthesized on lipid carriers before being transferred to lipopolysaccharide core structures. Rhizobium etli CE3 lipopolysaccharide is a model for understanding O-antigen biological function. CE3 O-antigen structure and genetics are known. However, proposed enzymology for CE3 O-antigen synthesis has been examined very little in vitro, and even the sugar added to begin the synthesis is uncertain. A model based on mutagenesis studies predicts that 2-acetamido-2,6-dideoxy-d-glucose (QuiNAc) is the first O-antigen sugar and that genes wreV, wreQ and wreU direct QuiNAc synthesis and O-antigen initiation. Previously, synthesis of UDP-QuiNAc was shown to occur in vitro with a WreV orthologue (4,6-hexose dehydratase) and WreQ (4-reductase), but the WreQ catalysis in this conventional deoxyhexose-synthesis pathway was very slow. This seeming deficiency was explained in the present study after WreU transferase activity was examined in vitro. Results fit the prediction that WreU transfers sugar-1-phosphate to bactoprenyl phosphate (BpP) to initiate O-antigen synthesis. Interestingly, WreU demonstrated much higher activity using the product of the WreV catalysis [UDP-4-keto-6-deoxy-GlcNAc (UDP-KdgNAc)] as the sugar-phosphate donor than using UDP-QuiNAc. Furthermore, the WreQ catalysis with WreU-generated BpPP-KdgNAc as the substrate was orders of magnitude faster than with UDP-KdgNAc. The inferred product BpPP-QuiNAc reacted as an acceptor substrate in an in vitro assay for addition of the second O-antigen sugar, mannose. These results imply a novel pathway for 6-deoxyhexose synthesis that may be commonly utilized by bacteria when QuiNAc is the first sugar of a polysaccharide or oligosaccharide repeat unit: UDP-GlcNAc → UDP-KdgNAc → BpPP-KdgNAc → BpPP-QuiNAc

Relationship Between Maternal Behavior During Pregnancy, Birth Outcome, and Early Childhood Development: An Exploratory Study

This study examines the relationship between maternal behavior during pregnancy, birth outcomes, and early childhood development. Specifically, in the context of four measures of maternal behavior during pregnancy (maternal smoking, drinking, prenatal care, and maternal weight gain), three measures of birth outcome (gestational age, birth length, and birth weight), and 32 exogenous covariates observed during pregnancy, we investigate the importance of maternal choices during pregnancy and birth outcomes in forecasting child health (as indicated by height and weight), child behavioral problems, and a child math/reading test score at age five or six. Strikingly, birth outcomes have virtually no structural/causal effects on early childhood developmental outcomes, and only maternal smoking and drinking during pregnancy have some effects on child height. Not surprisingly, family child-rearing environment has sizeable negative and positive effects on behavioral problems index and math/reading test score, respectively, and a mildly surprising negative effect on child height.endogeneity, birth weight, NLSY, prediction, simultaneous equations

An Econometric Model of Birth Inputs and Outputs

No abstract.

\u3cem\u3eIn Vitro\u3c/em\u3e Biosynthesis and Chemical Identification of UDP-\u3cem\u3eN\u3c/em\u3e-acetyl-d-quinovosamine (UDP-d-QuiNAc)

N-acetyl-d-quinovosamine (2-acetamido-2,6-dideoxy-d-glucose, QuiNAc) occurs in the polysaccharide structures of many Gram-negative bacteria. In the biosynthesis of QuiNAc-containing polysaccharides, UDP-QuiNAc is the hypothetical donor of the QuiNAc residue. Biosynthesis of UDP-QuiNAc has been proposed to occur by 4,6-dehydration of UDP-N-acetyl-d-glucosamine (UDP-GlcNAc) to UDP-2-acetamido-2,6-dideoxy-d-xylo-4-hexulose followed by reduction of this 4-keto intermediate to UDP-QuiNAc. Several specific dehydratases are known to catalyze the first proposed step. A specific reductase for the last step has not been demonstrated in vitro, but previous mutant analysis suggested that Rhizobium etli gene wreQ might encode this reductase. Therefore, this gene was cloned and expressed in Escherichia coli, and the resulting His6-tagged WreQ protein was purified. It was tested for 4-reductase activity by adding it and NAD(P)H to reaction mixtures in which 4,6-dehydratase WbpM had acted on the precursor substrate UDP-GlcNAc. Thin layer chromatography of the nucleotide sugars in the mixture at various stages of the reaction showed that WbpM converted UDP-GlcNAc completely to what was shown to be its 4-keto-6-deoxy derivative by NMR and that addition of WreQ and NADH led to formation of a third compound. Combined gas chromatography-mass spectrometry analysis of acid hydrolysates of the final reaction mixture showed that a quinovosamine moiety had been synthesized after WreQ addition. The two-step reaction progress also was monitored in real time by NMR. The final UDP-sugar product after WreQ addition was purified and determined to be UDP-d-QuiNAc by one-dimensional and two-dimensional NMR experiments. These results confirmed that WreQ has UDP-2-acetamido-2,6-dideoxy-d-xylo-4-hexulose 4-reductase activity, completing a pathway for UDP-d-QuiNAc synthesis in vitro

China: hyper-development and environmental crisis

Journal ArticleChina's spectacular economic growth has been one of the most dramatic developments in the global economy over the past quarter century. Between 1978 and 2004 the Chinese economy expanded at an annual rate of 9.4 per cent. No other large economy has ever grown so rapidly for so long in the economic history of the world. As a result, measured by purchasing power parity, China now accounts for about 15 per cent of the world output, and about one-third of the world economic growth that has taken place since 2000. However, China's economic growth has taken place at an enormous social and environmental price. A rapid increase in social and economic inequality, environmental degradation, mounting rural crisis, growing urban unemployment and poverty, pervasive government corruption, deteriorating public services (especially in basic education and health care), as well as escalating social unrest, have grown to dangerous levels and could potentially lead to an explosive situation. We focus in this essay on the environmental impact of accumulation and profit-oriented development in China. Given its enormous population and its growing importance in the global economy, the implications of China's environmental crisis go far beyond China itself. It has become an important and growing element in the developing global environmental crisis

China\u27s Food Pagodas: Looking Forward By Looking Back?

In this Article we provide a close analysis of the Chinese Dietary Guidelines – the Food Pagoda. Our focus on the dietary guidelines is motivated by two main considerations. First, the guidelines represent the most comprehensive, nationwide, state sponsored effort to educate the people of China about food. Like citizens in most countries, Chinese people are presented with numerous, often competing, messages from scientists, food gurus and online influencers. The dietary guidelines are different in that they are backed by an entire suite of governmental resources for nationwide dissemination through hospitals, schools, public billboards, TV and radio ads, among others. Among all the food advices and recommendations in China, it is the official dietary guidelines that have the greatest potential for changing dietary preferences. Second, understanding the Chinese dietary guidelines provides a useful basis for international comparison, since more than 100 countries around the world have dietary guidelines. Whether in the form of a pyramid or a plate, visualizations of the “ideal” national diet have become a common vector for official food advice. Examining the dietary guidelines therefore helps situate China in the broader context of government proffered food advice. In this Article, we examine the historical evolution of China’s Dietary Guidelines and their implications for environment, health, and animal welfare. Comparing the guidelines to longitudinal survey data about actual consumption provides a unique window on these issues, and in this Article we discuss what this glimpse may suggest for climate, health, and animal welfare going forward

Massive stars in massive clusters - IV. Disruption of clouds by momentum-driven winds

We examine the effect of momentum-driven OB-star stellar winds on a parameter space of simulated turbulent giant molecular clouds using smoothed particle hydrodynamic simulations. By comparison with identical simulations in which ionizing radiation was included instead of winds, we show that momentum-driven winds are considerably less effective in disrupting their host clouds than are H ii regions. The wind bubbles produced are smaller and generally smoother than the corresponding ionization-driven bubbles. Winds are roughly as effective in destroying the very dense gas in which the O stars are embedded, and thus shutting down the main regions of star-forming activity in the model clouds. However, their influence falls off rapidly with distance from the sources, so they are not as good at sweeping up dense gas and triggering star formation further out in the clouds. As a result, their effect on the star formation rate and efficiency is generally more negative than that of ionization, if they exert any effect at all.Peer reviewe

Power, Prestige, and Wealth: Indiana’s 1998 Award-winning School Districts

This research examines relationships between the Blue Ribbon school awards of 1998-1999 in Indiana and their per pupil expenditure, their local monetary sources, and their self-reports evidencing power, prestige, and wealth. An earlier study of 1994-1996 middle and high schools in Indiana found that total local funds were significantly greater in Blue Ribbon school districts than in non-Blue Ribbon school districts. Part of the conclusion suggested a follow up study of subsequent years. The ensuing report seeks to determine if school districts chosen for Blue Ribbon awards in 1998-1999 had greater local sources, or greater total expenditures per pupil, than non-Blue Ribbon school districts did. Did Blue Ribbon School districts spend more local funds than non Blue Ribbon School districts did? Did Blue Ribbon School districts spend more total (federal, state, and local) funds than non Blue Ribbon School districts did? A discussion related to the power, prestige, and wealth of the award-winning elementary schools follows the presentation of the findings