Direct electrochemistry of hemoglobin on carbonized titania nanotubes and its application in a sensitive reagentless hydrogen peroxide biosensor

Carbonized TiO(2) nanotubes (TNT/C) prepared by carbonization with organic polymers possess advantages combined from high conductivity of carbon and nanostructure of TiO(2) nanotubes. The material was used as a supporting matrix to immobilize a redox protein, hemoglobin (Hb), to explore its direct electron transfer ability. The apparent heterogeneous electron transfer rate constant (k(ET)) of Hb on TNT/C is 108s(-1), which is much higher than that in the reported works, demonstrating excellent direct electrochemistry behavior. The TNT/C-Hb modified glassy carbon electrode (GCE) demonstrates significant electrocatalytic activity for reduction of hydrogen peroxide with a small apparent Michaelis-Menten constant (87.5 microM). The TNT/C-Hb based H(2)O(2) sensor has a low detection limit (0.92 microM), fast response time (3s) and high dynamic response range (10(-6) to 10(-4)M), a much better performance than the reported works. These results demonstrate that a direct electrochemistry behavior can be significantly enhanced through simple carbon coating on a nanostructured material for higher reaction surface area and better conductivity. This work suggests that Hb-immobilized TNT/C has potential applications in a sensitive H(2)O(2) sensor.     

Bacteriocin of Pediococcus acidilactici HW01 Inhibits Biofilm Formation and Virulence Factor Production by Pseudomonas aeruginosa

Probiotics and Antimicrobial Proteins - Pseudomonas aeruginosa is a potential source of food contamination that leads to food spoilage and infections as a result of the generation of biofilm and...     

Electrically Control Lateral Shift Owning to Guided-Wave Surface Plasmon Resonance with a Lithium Niobate Prism

Electrically controlled lateral shift by an electro-optic crystal prism is studied theoretically. The resonance point of excitation of guided-wave surface plasmon resonance (GWSPR) can be controlled by altering the refractive index of the prism. That is to say, the positions corresponding to the least reflectivity and the largest lateral shift could be conveniently modulated while the lithium niobate prism is operated in an external electric field. The maximal lateral shift is obtained at the excitation of GWSPR when the thickness of the silver film is optimized. The results of numerical simulations confirm theoretical calculation.

     

Phosphate-buffered saline-based nucleofection of primary endothelial cells

Although various nonviral transfection methods are available, cell toxicity, low transfection efficiency, and high cost remain hurdles for in vitro gene delivery in cultured primary endothelial cells. Recently, unprecedented transfection efficiency for primary endothelial cells has been achieved due to the newly developed nucleofection technology that uses a combination of novel electroporation condition and specific buffer components that stabilize the cells in the electrical field. Despite superior transfection efficiency and cell viability, high cost of the technology has discouraged cardiovascular researchers from liberally adopting this new technology. Here we report that a phosphate-buffered saline (PBS)-based nucleofection method can be used for efficient gene delivery into primary endothelial cells and other types of cells. Comparative analyses of transfection efficiency and cell viability for primary arterial, venous, microvascular, and lymphatic endothelial cells were performed using PBS. Compared with the commercial buffers, PBS can support equally remarkable nucleofection efficiency to both primary and nonprimary cells. Moreover, PBS-mediated nucleofection of small interfering RNA (siRNA) showed more than 90% knockdown of the expression of target genes in primary endothelial cells. We demonstrate that PBS can be an unprecedented economical alternative to the high-cost buffers or nucleofection of various primary and nonprimary cells.     

Enhancing the processivity of a family B-type DNA polymerase of Thermococcus onnurineus and application to long PCR

Mechanisms that allow replicative DNA polymerases to attain high processivity are often specific to a given polymerase and cannot be generalised to others. Amplification efficiency is lower in family B-type DNA polymerases than in family A-type (Taq) polymerases because of their strong 3′–5′ exonuclease-activity. Here, we have red the exonuclease domain of the Thermococcus onnurineus NA1 (TNA1) DNA polymerase, especially Asn210 to Asp215 residues in Exo II motif (NXXXFD), to improve the processivity. N213D mutant protein had higher processivity and extension rate than the wild-type TNA1 DNA polymerase, retaining a lower mutation frequency than recombinant Taq DNA polymerase. Consequently, the N213D mutant could amplify target DNA up to 13.5 kb in length from human genomic DNA and 16.2 kb in length from human mitochondrial DNA while wild-type TNA1 amplified target DNA of 2.7 kb in length from human genomic DNA.     

Phosphate Solubilizing Bacillus megaterium mj1212 Regulates Endogenous Plant Carbohydrates and Amino Acids Contents to Promote Mustard Plant Growth

The current study was conducted to explore the potential of a phosphate solubilizing soil bacterium, Bacillus megaterium mj1212 for enhancing the growth of mustard plants. The newly isolated bacterial strain mj1212 was identified as B. megaterium using phylogenetic analysis and, its phosphate solubilization ability was shown by the clear zone formation on National Botanical Research Institute’s Phosphate medium. Moreover, the phosphate solubilization ability of B. megaterium mj1212 was enhanced by optimal culture conditions at pH 7.0 and 35 °C which might be due to the presence of malic and quinic acid in the culture medium. The beneficial effect of B. megaterium mj1212 in mustard plants was determined by an increasing shoot length, root length and fresh weight of plants. In the biochemical analysis revealed that chlorophyll, sucrose, glucose, fructose and amino acids (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ilu, Leu, Tyr, Phe, Lys, His, Arg and Pro) were higher in B. megaterium mj1212 treated plants, when compared to their control. The result of present study suggests that B. megaterium mj1212 treatment could be act as phosphate biofertilizer to improve the plant growth.     

Comparative and experimental studies on the relationship between body size and countershading in caterpillars

Countershading is a gradient of colouration in which the illuminated dorsal surfaces are darker than the unilluminated ventral surface. It is widespread in the animal kingdom and endows the body with a more uniform colour to decrease the chance of detection by predators. Although recent empirical studies support the theory of survival advantage conferred by countershading, this camouflage strategy has evolved only in some of the cryptic animals, and our understanding of the factors that affect the evolution of countershading is limited. This study examined the association between body size and countershading using lepidopteran larvae (caterpillars) as a model system. Specifically, we predicted that countershading may have selectively evolved in large-sized species among cryptic caterpillars if (1) large size constrains camouflage which facilitates the evolution of a trait reinforcing their crypsis and (2) the survival advantage of countershading is size-dependent. Phylogenetic analyses of four different lepidopteran families (Saturniidae, Sphingidae, Erebidae, and Geometridae) suggest equivocal results: countershading was more likely to be found in larger species in Saturniidae but not in the other families. The field predation experiment assuming avian predators did not support size-dependent predation in countershaded prey. Collectively, we found only weak evidence that body size is associated with countershading in caterpillars. Our results suggest that body size is not a universal factor that has shaped the interspecific variation in countershading observed in caterpillars.