Responses of Crop Water Use Efficiency to Climate Change and Agronomic Measures in the Semiarid Area of Northern China

It has long been concerned how crop water use efficiency (WUE) responds to climate change. Most of existing researches have emphasized the impact of single climate factor but have paid less attention to the effect of developed agronomic measures on crop WUE. Based on the long-term field observations/experiments data, we investigated the changing responses of crop WUE to climate variables (temperature and precipitation) and agronomic practices (fertilization and cropping patterns) in the semi-arid area of northern China (SAC) during two periods, 1983–1999 and 2000–2010 (drier and warmer). Our results suggest that crop WUE was an intrinsical system sensitive to climate change and agronomic measures. Crops tend to reach the maximum WUE (WUEmax) in warm-dry environment while reach the stable minimum WUE (WUEmin) in warm-wet environment, with a difference between WUEmax and WUEmin ranging from 29.0%-55.5%. Changes in temperature and precipitation in the past three decades jointly enhanced crop WUE by 8.1%-30.6%. Elevated fertilizer and rotation cropping would increase crop WUE by 5.6–11.0% and 19.5–92.9%, respectively. These results indicate crop has the resilience by adjusting WUE, which is not only able to respond to subsequent periods of favorable water balance but also to tolerate the drought stress, and reasonable agronomic practices could enhance this resilience. However, this capacity would break down under impact of climate changes and unconscionable agronomic practices (e.g. excessive N/P/K fertilizer or traditional continuous cropping). Based on the findings in this study, a conceptual crop WUE model is constructed to indicate the threshold of crop resilience, which could help the farmer develop appropriate strategies in adapting the adverse impacts of climate warming.     

Hepatocytes release ceramide-enriched pro-inflammatory extracellular vesicles in an IRE1α-dependent manner

Nonalcoholic steatohepatitis (NASH) is a lipotoxic disease wherein activation of endoplasmic reticulum (ER) stress response and macrophage-mediated hepatic inflammation are key pathogenic features. However, the lipid mediators linking these two observations remain elusive. We postulated that ER stress-regulated release of pro-inflammatory extracellular vesicles (EVs) from lipotoxic hepatocytes may be this link. EVs were isolated from cell culture supernatants of hepatocytes treated with palmitate (PA) to induce lipotoxic ER stress, characterized by immunofluorescence, Western blotting, electron microscopy, and nanoparticle tracking analysis. Sphingolipids were measured by tandem mass spectrometry. EVs were employed in macrophage chemotaxis assays. PA induced significant EV release. Because PA activates ER stress, we used KO hepatocytes to demonstrate that PA-induced EV release was mediated by inositol requiring enzyme 1α (IRE1α)/X-box binding protein-1. PA-induced EVs were enriched in C16:0 ceramide in an IRE1α-dependent manner, and activated macrophage chemotaxis via formation of sphingosine-1-phosphate (S1P) from C16:0 ceramide. This chemotaxis was blocked by sphingosine kinase inhibitors and S1P receptor inhibitors. Lastly, elevated circulating EVs in experimental and human NASH demonstrated increased C16:0 ceramide. PA induces C16:0 ceramide-enriched EV release in an IRE1α-dependent manner. The ceramide metabolite, S1P, activates macrophage chemotaxis, a potential mechanism for the recruitment of macrophages to the liver under lipotoxic conditions.     

Determination of free amino acids in burley tobacco by high performance liquid chromatography

A reversed-phase high performance liquid chromatographic method was developed for determining free amino acids in burley tobacco. The test was done by OPA/3-mercaptopropionic acid as the pre-column derivatizing reagent. Chromatographic column was Elitte C¹⁸ column (4.6 mm × 250 mm i.d., 5 μm). Mobile phase A was 18 mol/l NaAc (pH7.2) including 0.002%(v/v) triethylamine and 0.3%(v/v) furanidine. Mobile phase B was 100 mol/l NaAc (pH7.2)–acetonitrile–methanol (v/v = 1:2:2). The column temperature was 40 °C and the flow rate was 1.0 ml/min. The fluorescence detector was used with 350 nm excitation wave length and 450 nm emission wave length. The average recoveries of the method ranged from 95.3–100.7% with the relative standard deviation of 2.32–9.24%. The method is simple, accurate and has good repeatability. The results of the determination of seventeen kinds of free amino acids in burley leaves were produced by the way of different ratios of cake fertilizer and inorganic fertilizer. The results show that Aspartic acid has the highest content however ratio of cake fertilizer and inorganic fertilizer. The contents of most of the free amino acids are increased and then gradually decreased with the increase in organic manure. The contents of most of the free amino acids are very close at 15:85% ratio and 30:70% ratio of cake fertilizer and inorganic fertilizer. The total amount of free amino acids is the highest at 30:70% ratio of cake fertilizer and inorganic fertilizer. Considering comprehensively, the quality of burley leaves is the best at 30:70% ratio of cake fertilizer and inorganic fertilizer.     

Enhanced catalytic efficiency and enantioselectivity of epoxide hydrolase from Agrobacterium radiobacter AD1 by iterative saturation mutagenesis for (R)-epichlorohydrin synthesis

Applied Microbiology and Biotechnology - Enantioselective hydrolysis of epoxides by epoxide hydrolase (EH) is one of the most attractive approaches for the synthesis of chiral epoxides. So far,...     

Advances in the discovery of cathepsin K inhibitors on bone resorption

Cathepsin K (Cat K), highly expressed in osteoclasts, is a cysteine protease member of the cathepsin lysosomal protease family and has been of increasing interest as a target of medicinal chemistry efforts for its role in bone matrix degradation. Inhibition of the Cat K enzyme reduces bone resorption and thus, has rendered the enzyme as an attractive target for anti-resorptive osteoporosis therapy. Over the past decades, considerable efforts have been made to design and develop highly potent, excellently selective and orally applicable Cat K inhibitors. These inhibitors are derived from synthetic compounds or natural products, some of which have passed preclinical studies and are presently in clinical trials at different stages of advancement. In this review, we briefly summarised the historic development of Cat K inhibitors and discussed the relationship between structures of inhibitors and active sites in Cat K for the purpose of guiding future development of inhibitors.