The alternative respiratory pathway is involved in brassinosteroid-induced environmental stress tolerance in Nicotiana benthamiana.

Brassinosteroids (BRs), plant steroid hormones, play essential roles in modulating cell elongation, vascular differentiation, senescence, and stress responses. However, the mechanisms by which BRs regulate plant mitochondria and resistance to abiotic stress remain largely unclear. Mitochondrial alternative oxidase (AOX) is involved in the plant response to a variety of environmental stresses. In this report, the role of AOX in BR-induced tolerance against cold, polyethylene glycol (PEG), and high-light stresses was investigated. Exogenous applied brassinolide (BL, the most active BR) induced, while brassinazole (BRZ, a BR biosynthesis inhibitor) reduced alternative respiration and AOX1 expression in Nicotiana benthamiana. Chemical scavenging of H2O2 and virus-induced gene silencing (VIGS) of NbRBOHB compromised the BR-induced alternative respiratory pathway, and this result was further confirmed by NbAOX1 promoter analysis. Furthermore, inhibition of AOX activity by chemical treatment or a VIGS-based approach decreased plant resistance to environmental stresses and compromised BR-induced stress tolerance. Taken together, our results indicate that BR-induced AOX capability might contribute to the avoidance of superfluous reactive oxygen species accumulation and the protection of photosystems under stress conditions in N. benthamiana.

Responses of soil microbiome to steel corrosion.

The process of microbiologically influenced corrosion (MIC) in soils has received widespread attention. Herein, long-term outdoor soil burial experiments were conducted to elucidate the community composition and functional interaction of soil microorganisms associated with metal corrosion. The results indicated that iron-oxidizing (e.g., Gallionella), nitrifying (e.g., Nitrospira), and denitrifying (e.g., Hydrogenophaga) microorganisms were significantly enriched in response to metal corrosion and were positively correlated with the metal mass loss. Corrosion process may promote the preferential growth of the abundant microbes. The functional annotation revealed that the metabolic processes of nitrogen cycling and electron transfer pathways were strengthened, and also that the corrosion of metals in soil was closely associated with the biogeochemical cycling of iron and nitrogen elements and extracellular electron transfer. Niche disturbance of microbial communities induced by the buried metals facilitated the synergetic effect of the major MIC participants. The co-occurrence network analysis suggested possible niche correlations among corrosion related bioindicators.

Linear disulfide-containing low polymer as efficient DNA cleavage reagent.

A novel linear poly[1,7-bis(mercaptoacetyl)-1,4,7,10-tetraazacyclododecane] (PBMAC) containing macrocyclic polyamine was synthesized through oxidation of 1,7-bis(mercaptoacetyl)-1,4,7,10-tetraazacyclododecane (BMAC) and characterized. Gel electrophoresis experiments showed that PBMAC can promote the DNA cleavage more efficiently than its monomer under physiological conditions without any thiol additives. Fluorescence quenching and DNA melting experiments demonstrated that PBMAC has stronger binding ability with DNA than that of monomer.

Influence of Processing Parameters on the Thread and Spline Synchronous Rolling Process: An Experimental Study.

The thread and spline synchronous rolling (TSSR) process is a new developed rolling process, which can form the different profiles simultaneously in the process and can ensure the consistency of the relative position of different profiles of parts. However, the multi-meshing motions are intercoupling and the multi-deformation characteristics are intercoupling during the forming process. It can easily result in dimension overshoot, and even does not make the synchronous rolling process go smoothly. Exploring the influence of controllable processing parameters on the synchronous rolling process, especially the geometric parameters of rolled parts, is helpful to determine the parameters and control the size error for a smooth rolling process. Thus, in this paper, the effects of controllable geometric parameters and motion parameters such as billet diameter, radial feed-in speed, and rotational speed of synchronous rolling die on the TSSR process have been studied. The synchronous rolling experimental scheme was determined using an orthogonal experimental design method, and the geometric parameters of different tooth profiles of rolled parts were measured and analyzed. The experimental results indicated that: the uncoordinated meshing movement between different tooth profiles is more likely to cause tooth error of the splined section of the part; variations of the processing parameters are more likely to cause fluctuations in the size of the splined section of the part, and change of the billet diameter mainly affects the outside diameter of the threaded and splined sections, and the threaded and splined pitches are mainly affected by the motion parameters of the synchronous rolling die; the motion parameters of the rolling die should be matched and the lower rotational speed needs to match the lower radial feed-in amount per revolution; the ideal dimensional accuracy can be obtained by using an appropriate processing parameter combination, for example, the pitch error of the splined section of the part is less than 0.5 µm under one set of experimental conditions in this paper.

Effects of Ag, Cu or Ca addition on microstructure and comprehensive properties of biodegradable Zn-0.8Mn alloy.

Zn-0.8Mn (in wt%) alloy with good ductility is used for design of novel Zn-0.8Mn-0.4x (x = Ag, Cu or Ca) alloys. Hot extrusion not only eliminates brittleness of the as-cast alloys but also significantly improves their strengths. Among them, Zn-0.8Mn-0.4Ca exhibits the highest strength, Zn-0.8Mn-0.4Ag exhibits the highest ductility, but Zn-0.8Mn-0.4Cu exhibits the best combination of strength and ductility. The minor addition of Ag, Cu or Ca accelerates alloy degradation in simulated body fluid. However, Cu addition much improves in vitro biocompatibility and endows antibacterial ability of Escherichia coli. Overall, Zn-0.8Mn-0.4Cu alloy has the best comprehensive properties.

[Cloning and expression of a novel metallothionein gene LbMT2 from Limonium bicolor].

The full length cDNA of a novel metallothionein (LbMT2) gene was cloned from a cDNA library of Limonium bicolor. The LbMT2 gene cloned is 518 bp in length, which includes a 64 bp of 5' untranslated region (UTR) and a 205 bp of 3' untranslated region. This gene has an open reading frame (ORF) of 249 bp in length, encoding a protein of 82 amino acid residues with the molecular mass of 8.1 kDa and theoretical pI of 4.71. The expression of LbMT2 gene in L. bicolor in response to CuSO4, CdCl2, NaCl, cold, and PEG was further investigated using real time quantitative PCR. In both leaf and root of L. bicolor, the expression of LbMT2 was induced by CuSO4, CdCl2, NaCl, and cold, but inhibited by PEG stress. LbMT2 gene was inserted into a prokaryotic expression vector (pGEX-4T-2) to produce the recombinant expression vector pGEX-LbMT2. The expression of LbMT2 in E. coli BL21 was induced with IPTG, which produced a protein band with expected size of 35 kDa on SDS-PAGE.

[Correlation, seasonal and temporal variation of water-soluble ions of PM2.5 in Beijing during 2012-2013].

A total of 486 daily PM2.5 samples were collected at a background site, 3 urban sites, 4 suburban sites and a boundary transfer site during August 2012-July 2013. Mass concentrations of 9 water-soluble ions were obtained. The average mass concentration of the 9 ions was 60.5 µg x m(-3), and the order of concentration of ions was NO3- > SO4(2-) > NH4(+)- > Cl- > Na+ > K+ > Ca2+ > F- > Mg2+; Secondary inorganic species NO3-, SO4(2-) and NH4+ were the major components of water-soluble ions in PM2.5, with a contribution of 88% to the total ions of PM2.5. NO3- was the most fluctuated anion during the sampling period. With the increase of pollution level, the accumulation of SNA was obvious, the components that contained nitrogen, NO3- and NH4+, occupied the dominant position in the formation of the secondary components. NO3- had a relatively higher contribution to the accumulation of heavy pollution.

[Influence of seven absorption enhancers on nasal mucosa--assessment of toxicity].

OBJECTIVE: To study the influence of seven different absorption enhancers on nasal mucosa. METHODS: By testing last time of ciliary movement, velocity of ciliary movement, ciliary structural and specific cellular changes of nasal mucosa the influence of seven different absorption enhancers on nasal mucosa. RESULTS: The effect on lasting time of ciliary movement was 1%SDS>1%SDC>1%Brij35>5%Tween80>0.1%EDTA>5%HP-beta-CD>1%lecithin the effect on velocity of ciliary movement 1%Brij35>1%SDC>1%SDS>0.1%EDTA>1%lecithin>5%Tween80>5%HP-beta-CD,and the effect on ciliary structural and specific cellular changes of nasal mucosa 1%SDS approximately 1%SDC approximately 1%Brij35>5%Tween80>0.1%EDTA approximately 5% HP-beta-CD approximately 1%lecithin. CONCLUSION: The three methods have good correlation.

Sterol transfer by ABCG5 and ABCG8: in vitro assay and reconstitution.

ATP-binding cassette transporters G5 and G8 are half-transporters expressed on the apical membranes of enterocytes and hepatocytes that limit intestinal uptake and promote secretion of neutral sterols. Genetic defects that inactivate either half-transporter cause accumulation of cholesterol and plant sterols, resulting in premature coronary atherosclerosis. These observations suggest that G5 and G8 promote the translocation of sterols across membranes, but the primary transport substrate of the G5G8 complex has not been directly determined. Here we report the development of a sterol transfer assay using "inside-out" membrane vesicles from Sf9 cells expressing recombinant mouse G5 and G8. Radiolabeled cholesterol or sitosterol was transferred from donor liposomes to G5- and G8-containing membrane vesicles in an ATP-dependent and vanadate-sensitive manner; net transfer of cholesterol was associated with an increase in vesicular cholesterol mass. CTP, GTP, and UTP, as well as ATP, supported transfer but with lesser efficiency (ATP >> CTP > GTP > UTP). Transfer was specific for sterols and was stereoselective; minimal ATP-dependent and vanadate-sensitive transfer of cholesteryl oleate, phosphatidylcholine, or enantiomeric cholesterol was observed. These studies indicate that G5 and G8 are sufficient for reconstitution of sterol transfer activity in vitro and provide the first demonstration that sterols are direct transport substrates of the G5 and G8 heterodimer.