Influence of sucrose concentration and phosphate source on biomass and metabolite accumulation in adventitious roots of Pseudostellaria heterophylla

In this study, we investigated the induction of Pseudostellaria heterophylla adventitious root and the effects of sucrose concentration and phosphate source on biomass increase and metabolites accumulation. These roots were initially cultured in Murashige and Skoog medium for 4 weeks. IBA 3.0 mg L^?1 proved to be the best auxin for inducing adventitious roots and the frequency of adventitious roots induced from roots (100 %) was higher than that from leaves (78 %) and stems (27 %). The medium with 4 % sucrose resulted in the optimum biomass i.e. 1.04 g/flask DW, and the content of saponin and polysaccharides reached the peak i.e. 0.676 and 24.4 %, respectively. With regards to phosphate source, 1.25 mM phosphate concentration was more favorable for biomass of roots (0.87 g/flask of DW), whereas the optimum saponin (0.74 %) and polysaccharides (22.09 %) were achieved with 2.5 mM phosphate. However, the saponin content at 2.5 mM phosphate did not show significant difference from the saponin content at 0.625 mM (0.69 %) or 3.75 mM phosphate (0.69 %).     

Nanoparticle-tethered NAD+ with in situ cofactor regeneration

A new and simple route for the preparation of immobilized NAD⁺ on carboxyl-activated silica nanoparticles activated by γ-aminpropyltriethoxysilane and glutaric anhydride was developed. In addition, formate dehydrogenase, keto-reductase and the silica nanoparticle-attached NAD⁺ were applied to catalyze the coupled reactions for production of l-lactate with the cofactor regenerated within the reaction cycle. As indicated by thermogravimetric analysis and FT-IR, the silica nanoparticles were successfully activated and the loading of carboxyl groups was 0.53 mmol g^?1 particle. The amount of immobilized NAD⁺ on the support was 73 mg g^?1 particle. With 0.2 M pyruvate and 3 M formate, 0.16 M l-lactate was produced after the coupled reactions. The immobilized system showed excellent efficiency and stabilities in recycling, and it retained 60 % residual activity even after six reuses.     

Genetic manipulation revealing an unusual N-terminal region in a stand-alone non-ribosomal peptide synthetase involved in the biosynthesis of ramoplanins

Ramoplanins produced by Actinoplanes are new structural class of lipopeptide and are currently in phase III clinical trials for the prevention of vancomycin-resistant enterococcal infections. The depsipeptide structures of ramoplanins are synthesized by non-ribosomal peptide synthetases (NRPS). Romo-orf17, a stand-alone NRPS, is responsible for the recruitment of Thr into the linear NRPS pathways for which the corresponding adenylation domain is absent. Here, systematical gene inactivation and complementation have been carried out in a Actinoplanes sp. using homologous recombination and site-specific integration methods. A hybrid gene coding for the N-terminal region of the stand-alone NRPS and the A-PCP domains of a heterologous NRPS restored production of ramoplanins. The results elucidate the unusual N-terminal region which is essential for the biosynthesis of ramoplanins.     

Identification and characterization of P GCW14 : a novel, strong constitutive promoter of Pichia pastoris

The available promoters in the Pichia pastoris expression platform are still limited. We selected and identified a novel strong constitutive promoter, P _GCW14 , and tested its promoter activity using enhanced green fluorescent protein (EGFP) as a reporter. Potential promoter regions of P _GCW14 were cloned upstream of the EGFP gene and promoter activity was analyzed by measuring fluorescence intensity. P _GCW14 exhibited significantly stronger promoter activity than the classic strong constitutive promoters P _TEF1 and P _GAP under various carbon sources, suggesting that P _GCW14 is a strong and constitutive promoter. Hence, P _GCW14 can be used as a promoter for high-level expression of heterologous proteins.     

Normalization of miRNA qPCR high-throughput data: a comparison of methods

Low-density quantitative real-time PCR (qPCR) arrays are often used to profile expression patterns of microRNAs in various biological milieus. To achieve accurate analysis of expression of miRNAs, non-biological sources of variation in data should be removed through precise normalization of data. We have systematically compared the performance of 19 normalization methods on different subsets of a real miRNA qPCR dataset that covers 40 human tissues. After robustly modeling the mean squared error (MSE) in normalized data, we demonstrate lower variability between replicates is achieved using various methods not applied to high-throughput miRNA qPCR data yet. Normalization methods that use splines or wavelets smoothing to estimate and remove Cq dependent non-linearity between pairs of samples best reduced the MSE of differences in Cq values of replicate samples. These methods also retained between-group variability in different subsets of the dataset.     

Arbuscular mycorrhizal fungi-enhanced resistance against Phytophthora sojae infection on soybean leaves is mediated by a network involving hydrogen peroxide, jasmonic acid, and the metabolism of carbon and nitrogen

The arbuscular mycorrhizal fungi (AMF) enhance the resistance to pathogen infection in host plant. However, it is unclear how the AMF are involved in the systemic acquired resistance of host plant against pathogen. Here, an experiment was carried out to clarify the role of the AMF in soybean’s defense against the infection from pathogen Phytophthora sojae. It was found that the AMF contributed to the resistance of soybean against Phytophthora sojae by the release of hydrogen peroxide and by the accumulation of jasmonic acid in response to pathogenic invasion. Furthermore, the trade of nitrogen (N) from the fungus for carbon from the host was accelerated in the AM symbiosis in the defense reaction, which was indicated by the increased soluble sugar level, NO content and enzyme activities involved in N metabolism in the AM symbiosis.     

A role for Ethylene-Insensitive3 in the regulation of hydrogen peroxide production during seed germination under high salinity in Arabidopsis

The Arabidopsis Ethylene-Insensitive3 (EIN3) has received attention recently and has been shown to be involved in the regulation of multitude of responses ranging from biotic stress defense and development to hormone interaction. To better understand the roles of EIN3 in plants response to salinity stress during germination and post-germination development, seeds of two EIN3 deficient mutant and a EIN3 overexpression mutant of Arabidopsis were analyzed under salinity and compared with Col-0 as control. The results showed that the ein3-1eil1-1 double mutant (lacking EIN3 and EIN3-Like1) and ein3-1 (lacking EIN3) were hypersensitive to high salinity (>150 mM NaCl), while EIN3 overexpression mutant (EIN3ox) displayed enhanced tolerance, indicating that EIN3 plays important roles during seed germination under salinity. In addition, we also found that the two EIN3 deficient mutant seedlings accumulate high levels of hydrogen peroxide (H₂O₂), which was thought to be an inhibitor of germination under salinity before, suggesting that EIN3 may function as a negative regulator of reactive oxygen species metabolism in germinating seeds under salinity. Taken together, our studies provide insights that EIN3 promotes seed germination under salinity, at least in part, through modulating concentration of H₂O₂ in germinating seeds.     

Synergistic effect of colonization with arbuscular mycorrhizal fungi improves growth and drought tolerance of Plukenetia volubilis seedlings

The objective of this study was to investigate the effects of arbuscular mycorrhizal fungus (AMF) inoculation on plant growth and drought tolerance in seedlings of a promising oilseed crop, Sacha Inchi (Plukenetia volubilis L.), under well-watered or drought conditions. AMF inoculation was applied in four treatments: without AMF inoculation, Glomus versiforme, Paraglomus occultum, or combination of both microorganism inoculations. The results showed that AMF colonization significantly enhanced the growth of Sacha Inchi seedlings regardless of soil water conditions, and the greatest development was reached in plants dually inoculated under well-watered conditions. G. versiforme was more efficient than P. occultum. Plants inoculated with both symbionts had significantly greater specific leaf area, leaf area ratio and root volume when compared with the uninoculated control, G. versiforme, and P. occultum treatments alone, indicating a synergistic effect in the two AMF inoculation. Photosynthetic rate and water-use efficiency were stimulated by AMF, but not stomatal conductance. Inoculation with AM fungus increased antioxidant enzymes activities including guaiacol peroxidase and catalase, thus lowering hydrogen peroxide accumulation and oxidative damage, especially under drought stress conditions. However, proline content showed little change during drought stress and AMF colonization conditions, which suggested that proline accumulation might not serve as the main compound for osmotic adjustment of the studied species. These results indicate that AMF inoculation stimulated growth and enhanced drought tolerance of Sacha Inchi seedlings, through alterations in morphological, physiological and biochemical traits. This microbial symbiosis might be an effective cultivation practice in improving the performance and development for Sacha Inchi plants.     

Rubia austrozhejiangensis sp. nov. (Rubiaceae) from Zhejiang,China

Rubia austrozhejiangensis Z. P. Lei, Y. Y. Zhou & R. W. Wang, a new species of Rubiaceae from China, is described and illustrated. The new species is similar to R. ovatifolia Z. Ying Zhang and R. argyi (H. Lév. & Vaniot) H. Hara ex Lauener, but differs from the former in having stems and branches cylindrical, not quadrate‐angled, long‐ovate to ovate‐lanceolate leaf blades, many‐flowered inflorescence, and smaller mericarps, 3–4 mm in diameter. In R. ovatifolia, stems and branches are quadrate‐angled, leaf blades ovate, ovate‐cordate to rounded cordate, and the inflorescences are sparsely flowered. Compared to R. argyi, the new species has cylindrical, not quadrate‐angled stems and branches, leaf blades that are long‐ovate to ovate‐lanceolate, 3–5‐veined, and slightly reflexed corolla lobes. In R. argyi, stems and branches are quadrate‐angled or winged, the corolla lobes are spreading, and the mericarps are 5–7 mm in diameter.     

The making of an ‘ideal’ live-in migrant care worker: recruiting,training, matching and disciplining

This essay investigates the contested processes through which gender and racial ideologies are practised and thereby place specific groups of women in particular gendered and racialized labour markets. The migration of female live-in care workers to Taiwan exemplifies how gender and racial ideologies are embodied in everyday practices that justify the paid care work done by these women and that produce their subordinate status. In this essay, I take the problematic of representation of ‘migrant care workers’ as a point of entry, to investigate how a gendered-racialized ideology is utilized to legitimate and naturalize the gendered-racialized division of care labour within the global capitalist context.