[Effects of weeds on crops and their ecological control in ecological agriculture of Chinese materia medica].

Weeds is one of the important parts of agricultural ecosystem of Chinese materia medica. Weeds is a double-edged sword with advantages and disadvantages for the cultivated medicinal plants. In this study, we firstly analyzed the positive and negative effects of weeds on the yield and quality of Chinese materia medica. We then explored the possible mechanisms for the weeds' positive effects from the aspects of interspecific relationship, soil microecological environment, light environment, natural control of pests and so on. We also summarized three basic principles of weed control, that is, "making medicinal plants and weeds coexist harmoniously, achieving the overall optimum growth of medicinal plants", "prevention first, integrated control" and "preserving beneficial weeds and increasing their beneficial effects, removing harmful weeds and control their adverse effects". Finally, we introduced several common weed ecological control technology in field of the cultivated medicinal plants in China, including technology of controlling weeds by no-tillage, stral mulch, rotation, alternative herbs, competitive crops, and allelopathy. This study is aimed to apply the ecology theory to guide weed management and control, so as to achieve the goal of advantages promotion and disadvantages elimination of weeds to cultivated medicinal plants, making weeds into treasure and to promote the sustainable and healthy development of Chinese medicinal materials production and the protection of weed diversity.

Functional Analysis of the Ferric Uptake Regulator Gene fur in Xanthomonas vesicatoria.

Iron is essential for the growth and survival of many organisms. Intracellular iron homeostasis must be maintained for cell survival and protection against iron toxicity. The ferric uptake regulator protein (Fur) regulates the high-affinity ferric uptake system in many bacteria. To investigate the function of the fur gene in Xanthomonas vesicatoria (Xv), we generated a fur mutant strain, fur-m, by site-directed mutagenesis. Whereas siderophore production increased in the Xv fur mutant, extracellular polysaccharide production, biofilm formation, swimming ability and quorum sensing signals were all significantly decreased. The fur mutant also had significantly reduced virulence in tomato leaves. The above-mentioned phenotypes significantly recovered when the Xv fur mutation allele was complemented with a wild-type fur gene. Thus, Fur either negatively or positively regulates multiple important physiological functions in Xv.

Co-regulation of transcellular and paracellular leak across microvascular endothelium by dynamin and Rac.

Increased permeability of the microvascular endothelium to fluids and proteins is the hallmark of inflammatory conditions such as sepsis. Leakage can occur between (paracellular) or through (transcytosis) endothelial cells, yet little is known about whether these pathways are linked. Understanding the regulation of microvascular permeability is essential for the identification of novel therapies to combat inflammation. We investigated whether transcytosis and paracellular leakage are co-regulated. Using molecular and pharmacologic approaches, we inhibited transcytosis of albumin in primary human microvascular endothelium and measured paracellular permeability. Blockade of transcytosis induced a rapid increase in paracellular leakage that was not explained by decreases in caveolin-1 or increases in activity of nitric oxide synthase. The effect required caveolin-1 but was observed in cells depleted of clathrin, indicating that it was not due to the general inhibition of endocytosis. Inhibiting transcytosis by dynamin blockade increased paracellular leakage concomitantly with the loss of cortical actin from the plasma membrane and the displacement of active Rac from the plasmalemma. Importantly, inhibition of paracellular leakage by sphingosine-1-phosphate, which activates Rac and induces cortical actin, caused a significant increase in transcytosis of albumin in vitro and in an ex vivo whole-lung model. In addition, dominant-negative Rac significantly diminished albumin uptake by endothelia. Our findings indicate that transcytosis and paracellular permeability are co-regulated through a signaling pathway linking dynamin, Rac, and actin.