A chondroitin sulfate purified from shark cartilage and bovine serum albumin interaction activity.

Chondroitin sulfate (CS) was extracted and purified from shark cartilage, and its interaction with bovine serum albumin (BSA) were studied. The content of chondroitin sulfate in shark cartilage was 29.97 % using the 1,9-dimethyl-methylene blue method. The molecular weight of CS was determined to be 62.464 kDa by high-performance gel permeation chromatography. UV and FT-IR spectroscopy identified the characteristics of CS and its functional group information. NMR spectroscopy and disaccharide derivatization revealed that CS was predominantly composed of disulfated disaccharides, specifically ΔDi4,6S. Fluorescence quenching experiments indicated that the interaction between CS and BSA exhibited static quenching, with a binding site number of 1. The binding process was primarily mediated by van der Waals forces and hydrogen bonds. Furthermore, synchronous and 3D fluorescence spectroscopy demonstrated that CS had minimal impact on the polarity and hydrophobicity of the microenvironment surrounding Tyr and Trp residues. UV-vis absorption and circular dichroism (CD) spectroscopy demonstrated the altered structure of BSA. The molecular docking analysis revealed that CS formed hydrogen bonds and salt bridges with BSA, predominantly binding to the IIA substructure domain of BSA. Investigating the interaction between CS and BSA holds the potential for enhancing its applications in drug delivery and tissue engineering endeavors.

Effects of different light conditions on transient expression and biomass in Nicotiana benthamiana leaves.

In the process of the production of recombinant proteins by using an Agrobacterium-mediated transient gene expression system, the effectiveness of the control of light conditions pre- and post-agroinfiltration on efficiency of transient expression is worth being evaluated. In this study, Nicotiana benthamiana plants were used as a bioreactor to investigate the effects of different light conditions pre- and post-agroinfiltration on the transient expression of green fluorescent protein (GFP). The results showed that the plants grown under light condition for 5 weeks had the highest level of transient expression among those grown for 4-8 weeks. In the pre-agroinfiltration, the level of transient expression of GFP was obviously decreased by the increase in light intensity or by the shortening of the photoperiod. Although the shortening of the photoperiod post-agroinfiltration also decreased the level of transient expression, moderate light intensity post-agroinfiltration was needed for higher level of transient expression efficiency. However, there was no strong correlation between the transient expression efficiency and plant growth. The results suggested that light condition was an important factor affecting the level of transient expression in plants. Hence, light conditions should be optimized to obtain higher productivity of recombinant protein from transient expression systems.

Advances in emission control of diesel vehicles in China.

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NOx emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH3. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.

Alleviative effects of magnetic Fe3O4 nanoparticles on the physiological toxicity of 3-nitrophenol to rice (Oryza sativa L.) seedlings.

In the present study, we explored whether magnetic iron oxide nanoparticles (MNPs-Fe3O4) can be used to alleviate the toxicity of 3-nitrophenol (3-NP) to rice (Oryza sativa L.) seedlings grown under hydroponic conditions. The results showed that 3-NP from 7 to 560 µM decreased the growth, photochemical activity of the photosystem II (PS II), and chlorophyll content of the seedlings in a concentration-dependent manner. In the presence of 3-NP, 2,000 mg L-1 MNPs-Fe3O4 were added to the growth medium as the absorbents of 3-NP and then were separated with a magnet. The emergence of MNPs-Fe3O4 effectively alleviated the negative effects of 3-NP on rice seedlings. In addition, the long-term presence of MNPs-Fe3O4 (from 100 to 2,000 mg L-1) in the growth medium enhanced the growth, production of reactive oxygen species (ROS), activities of antioxidant enzymes, photochemical activity of PS II, and chlorophyll content of the rice seedlings. These results suggest that MNPs-Fe3O4 could be used as potential additives to relieve the physiological toxicity of 3-NP to rice seedlings.

The involvement of extracellular ATP in regulating the stunted growth of Arabidopsis plants by repeated wounding.

BACKGROUND: Extracellular ATP (exATP) has been shown to act as a signal molecule for regulating growth, development, and responses of plants to the external environment. RESULTS: In this study, we investigated the possible involvement of exATP in regulating the stunted growth caused by repeated wounding. The present work showed that the repeated wounding caused the decreases in leaf area, fresh weight, dry weight, and root length of Arabidopsis seedlings, while the exATP level was enhanced by the repeated wounding. Repeated application of exogenous ATP had similar effects on the plant growth, as the repeated wounding. Through the comparison of p2k1-3 mutant (in which T-DNA disrupted the gene coding P2K1, as exATP receptor) and wide type (WT) plants, it was found that the mutation in P2K1 decreased the sensitivity of plant growth to the repeated wounding and exogenous ATP application. Further works showed that the ibuprofen (IBU, an inhibitor of jasmonate biosynthesis) partially rescued the wound-induced growth degradation. In comparison, the P2K1 mutation partly rescued the wound-induced growth degradation, whereas this mutation failed to do so in the wounded seedlings treated with IBU, indicating that the role of exATP in regulating the growth degradation by repeated wounding could be linked to the JA signaling pathway. CONCLUSIONS: In conclusion, these results indicate that exATP could be a regulator for the stunted growth of plants by repeated wounding.

Extracellular ATP is involved in regulating Arabidopsis seed germination.

MAIN CONCLUSION: Extracellular ATP level induced a transient increase during germination of Arabidopsis seeds, and extracellular ATP could negatively regulate the seed germination by its receptor, DORN1. Extracellular ATP (exATP) acts as a signal molecule for regulating growth, development, and responses of plants to external environments. In this study, we investigated the possible involvement of exATP in regulating the seed germination of Arabidopsis thaliana. Treatments of Arabidopsis seeds with exogenous ATP delayed seed germination, suggesting that exATP could be a repressor for seed germination. During the germination of Arabidopsis seeds, the exATP level of the seeds presented a transient increase. When exogenous application of the glucose-hexokinase system effectively decreased the exATP level of the Arabidopsis seeds during germination, the percentage of germination was significantly enhanced, while the products of ATP hydrolysis had no effects on the germination. Further studies showed that the seeds of dorn 1-3 mutant plants (mutation in exATP receptor) showed a higher germination percentage, compared to the seeds of wide type (WT) plants. In addition, the dorn 1-3 mutant seeds were less sensitive to the delay-effect of exogenous ATP on seed germination than the WT seeds. The dorn 1-3 mutant seeds presented a higher GA (gibberellin) content, lower ABA (abscisic acid) content, and lower ratio of ABA/GA contents before the imbibition, compared to the WT seeds. The regulation of seed germination by exATP was dependent on the external temperature. These data suggest that exATP is involved in regulating Arabidopsis seed germination.

Restoring the Oxidase-Like Activity of His@AuNCs for the Determination of Alkaline Phosphatase.

In this paper, we propose a simple colorimetric method for the sensitive and selective detection of alkaline phosphatase (ALP) activity based on the turn off/turn on oxidase mimic activity of His@AuNCs. His@AuNCs/graphene oxide hybrids (His@AuNCs/GO) were easily obtained using the self-assembly method with poly (diallyldimethylammonium chloride) (PDDA)-coated GO and showed high oxidase-like activity compared with His@AuNCs. We found that the pyrophosphate ion (P2O74-, PPi) could effectively inhibit the oxidase mimic activity of His@AuNCs/GO, and the hydrolysis of PPi by ALP restored the inhibited activity of His@AuNCs/GO, enabling them to efficiently catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to generate the blue oxidized product oxTMB. The intensity of the color showed a linear dependency with the ALP activity. ALP was detected in the linear range of 0-40 mU/mL with a low detection limit (LOD) of 0.26 mU/mL (S/N = 3). The proposed method is fast, easy, and can be applied to monitor the ALP activity in serum samples accurately and effectively, which suggests its practicability and reliability in the detection of ALP activity in clinical practice.

Effects of plant growth regulators on transient expression of foreign gene in Nicotiana benthamiana L. leaves.

BACKGROUND: In the last decades, replicating expression vectors based on plant geminivirus have been widely used for enhancing the efficiency of plant transient expression. By using the replicating expression vector derived from bean yellow dwarf virus and green fluorescent protein as a reporter, we investigated the effects of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine, as three common plant growth regulators, on the plant biomass and efficiency of transient expression during the process of transient expression in Nicotiana benthamiana L. leaves. RESULTS: With the increase of the concentration of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine (from 0.1 to 1.6 mg/L), the fresh weight, dry weight, and leaf area of the seedlings increased first and then returned to the levels similar to the controls (without chemical treatment). The treatment with α-naphthalene acetic acid at 0.2 and 0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.4 mg/L α-naphthalene acetic acid and was increased about by 19%, compared to the controls. Gibberellins3 at 0.1-0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.2 mg/L gibberellins3 and was increased by 25%. However, the application of 6-benzyladenine led to decrease in the level of transient expression of green fluorescent protein. CONCLUSIONS: The appropriate plant growth regulators at moderate concentration could be beneficial to the expression of foreign genes from the Agrobacterium-mediated transient expression system in plants. Thus, appropriate plant growth regulators could be considered as exogenous components that are applied for the production of recombinant protein by plant-based transient expression systems.