Fluorination of BC3 nanotubes: DFT studies

We have studied the adsorption of atomic and molecular fluorines on a BC₃ nanotube by using density functional calculations. It was found that the adsorption of atomic fluorine on a C atom of the tube surface is energetically more favorable than that on a B atom by about 0.97 eV. The adsorption of atomic fluorine on both C and B atoms significantly affects the electronic properties of the BC₃ tube. The HOMO-LUMO energy gap is considerably reduced from 2.37 to 1.50 and 1.14 eV upon atomic F adsorption on B and C atoms, respectively. Molecular fluorine energetically tends to be dissociated on B atoms of the tube surface. The associative and dissociative adsorption energies of F₂ were calculated to be about ?0.42 and ?4.79 eV, respectively. Electron emission density from BC₃ nanotube surface will be increased upon both atomic and molecular fluorine adsorptions due to work function decrement.     

Temperature‐dependent conformational change affecting Tyr11 and sweetness loops of brazzein

The sweet protein brazzein, a member of the Csβα fold family, contains four disulfide bonds that lend a high degree of thermal and pH stability to its structure. Nevertheless, a variable temperature study has revealed that the protein undergoes a local, reversible conformational change between 37 and 3°C with a midpoint about 27°C that changes the orientations and side‐chain hydrogen bond partners of Tyr8 and Tyr11. To test the functional significance of this effect, we used NMR saturation transfer to investigate the interaction between brazzein and the amino terminal domain of the sweet receptor subunit T1R2; the results showed a stronger interaction at 7°C than at 37°C. Thus the low temperature conformation, which alters the orientations of two loops known to be critical for the sweetness of brazzein, may represent the bound state of brazzein in the complex with the human sweet receptor. Proteins 2013; © 2012 Wiley Periodicals, Inc.     

Impact of winter pruning of pomegranate trees on Aphis punicae (Hemiptera,Aphididae) and its natural enemies in Tunisia

Winter pruning is a cultural practice used to modify vegetative growth, which is likely to affect the development of pests. However, it has been poorly defined as a cultural method for diminishing the population levels of the pomegranate aphid Aphis punicae (Hemiptera, Aphididae) in pomegranate orchards. This study aimed to evaluate the impact of winter pruning of pomegranate on A. punicae population and their natural enemies. The results showed that winter pruning significantly decreased the population of A. punicae (p < 0.05) in pomegranate. Also, number of natural enemies decreased in pomegranate trees after winter pruning. This technical practice affects the number of winged and wingless individuals, the mean relative growth rate, the specific age of the population and the infestation rate. Winter pruning for A. punicae control in pomegranate orchards is highly recommended.     

Does Dietary vitamin E or C Decrease Egg Yolk Cholesterol?

An experiment was conducted to determine the effect of dietary vitamin E and C on serum metabolites, yolk cholesterol, egg quality, and performance of layer hens. One hundred sixty-eight commercial Hy-Line W-36 layer hens were randomly divided into seven groups and six replicates with four hens in each. Dietary treatments were introduced after the pre-experimental period (10 days) to adjust egg production. Treatments were levels of vitamin E or C (100, 200, and 400 mg/kg diet) supplementation to the basal diet for 4 weeks, whereas the control group received no supplementation. Egg production, egg weight, and feed consumption were recorded during the study. Shell thickness, Haugh unit score, yolk color, yolk weight, yolk cholesterol, and blood parameters were measured at the end of experiment. There was no significant effect of dietary vitamin E or C on hen performance. Egg yolk cholesterol concentrations decreased linearly by antioxidant vitamin supplementation (P?<?0.01). Egg yolk cholesterol reduction did not have any negative effect on egg production rate. Antioxidants, especially vitamin C, increased serum glucose concentration (P?<?0.05). Serum total cholesterol content did not change by vitamin supplementation but cholesterol in high-density lipoprotein (HDL-C) decreased and cholesterol in low-density lipoprotein (LDL-C) increased (P?<?0.05), as dietary vitamin E or C supplementation increased in diets. These results are in conflict with the previous hypothesis that antioxidants have a role in LDL-C removal from the blood or increasing HDL-C. Vitamin E was more effective than vitamin C in this case and if these results are confirmed by further studies, they may result to revision in researchers’ point of view about antioxidant especially in human medicine.     

Critical negative regulation of type 1 T cell immunity and immunopathology by signaling adaptor DAP12 during intracellular infection

Transmembrane signaling adaptor DAP12 has increasingly been recognized for its important role in innate responses. However, its role in the regulation of antimicrobial T cell responses has remained unknown. In our current study, we have examined host defense, T cell responses, and tissue immunopathology in models of intracellular infection established in wild-type and DAP12-deficient mice. During mycobacterial infection, lack of DAP12 leads to pronounced proinflammatory and Th1 cytokine responses, overactivation of Ag-specific CD4 and CD8 T cells of type 1 phenotype, and heightened immunopathology both in the lung and lymphoid organs. DAP12-deficient airway APC display enhanced NF-kappaB activation and cytokine responses upon TLR stimulation or mycobacterial infection in vitro. Of importance, adoptive transfer of Ag-loaded DAP12-deficient APC alone could lead to overactivation of transferred transgenic or endogenous wild-type T cells in vivo. We have further found that the immune regulatory role by DAP12 is not restricted only to intracellular bacterial infection, since lack of this molecule also leads to uncontrolled type 1 T cell activation and severe immunopathology and tissue injury during intracellular viral infection. Our study thus identifies DAP12 as an important novel immune regulatory molecule that acts, via APC, to control the level of antimicrobial type 1 T cell activation and immunopathology.     

Androgen receptor regulation of the versican gene through an androgen response element in the proximal promoter

Versican, one of the key components of prostatic stroma, plays a central role in tumor initiation and progression. Here, we investigated promoter elements and mechanisms of androgen receptor (AR)-mediated regulation of the versican gene in prostate cancer cells. Using transient transfection assays in prostate cancer LNCaP and cervical cancer HeLa cells engineered to express the AR, we demonstrate that the synthetic androgen R1881 and dihydrotestosterone stimulate expression of a versican promoter-driven luciferase reporter vector (versican-Luc). Further, both basal and androgen-stimulated versican-Luc activities were significantly diminished in LNCaP cells, when AR gene expression was knocked down using a short hairpin RNA. Methylation-protection footprinting analysis revealed an AR-protected element between positions +75 and +102 of the proximal versican promoter, which strongly resembled a consensus steroid receptor element. Electrophoretic mobility shift and supershift assays revealed strong and specific binding of the recombinant AR DNA binding domain to oligonucleotides corresponding to this protected DNA sequence. Site-directed mutagenesis of the steroid receptor element site markedly diminished R1881-stimulated versican-Luc activity. In contrast to the response seen using LNCaP cells, R1881 did not significantly induce versican promoter activity and mRNA levels in AR-positive prostate stromal fibroblasts. Interestingly, overexpression of beta-catenin in the presence of androgen augmented versican promoter activity 10- and 30-fold and enhanced versican mRNA levels 2.8-fold in fibroblasts. In conclusion, we demonstrate that AR transactivates versican expression, which may augment tumor-stromal interactions and may contribute to prostate cancer progression.     

Tenascin-C as a noninvasive biomarker of coronary artery disease

Molecular Biology Reports - Coronary artery disease (CAD), is the leading cause of mortality and morbidity worldwide. Tenascin-C (TNC) with high expression levels in inflammatory and cardiovascular...