Effects of equilibration time, precooling and developmental stage on the survival of mouse embryos cryopreserved by vitrification

Factorial experiments were carried out to examine the effects of equilibration time, precooling and developmental stage on the postthaw in vitro survival of vitrified mouse embryos. Eight-cell embryos, compacted morulae, or blastocysts were cryopreserved using vitrification Solution 1 (VS1; 10% glycerol + 20% propylene glycol), and vitrification Solution 2 (VS2; 25% glycerol + 25% propylene glycol) in phosphate buffered saline + 10% calf serum. Each embryo stage group was first equilibrated in VS1 for 5, 10 or 20 min and then exposed to either a precooled ( approximately 4 degrees C) or nonprecooled ( approximately 20 degrees C) VS2 in a 0.25-ml straw before they were plunged directly into liquid nitrogen. Results of this study showed an interaction between precooling, equilibration time and developmental stage which affect significantly post-thaw embryo survival (P< 0.05). High survival rates were obtained after 10 min equilibration in VS1 irrespective of the embryo developmental stage. Precooling of the VS2 significantly improved the survival mainly of blastocysts. However, eight-cell and morula-stage embryos also showed high survival rates when they were exposed to precooled VS2 after 5 min equilibration in VS1. It was further observed that morulae usually exhibit high survival rates, and vitrification conditions are more critical for early and advanced stage embryo development.     

A Comparative Study of a Novel Anti-reflective Layer to Improve the Performance of a Thin-Film GaAs Solar Cell by Embedding Plasmonic Nanoparticles

In this research work, a systematic design of a novel anti-reflective layer using embedded plasmonic nanoparticles is investigated for a thin-film GaAs solar cell. First, an anti-reflective layer that is made from ITO or SiO₂ is assumed in which Al nanoparticles are embedded inside them to manipulate the absorption and hence the photocurrent of a 500-nm GaAs solar cell. It is investigated that the Al nanoparticles embedded inside the anti-reflective coating improve the photocurrent of a GaAs solar cell. For instance, the 15.37 mA photocurrent is obtained for 500-nm bare GaAs cell, and it reached to 17.25 mA/cm² and 20.18 mA/cm² when an ITO anti-reflection is used with Al nanoparticles on top and inside that, respectively. It increases to 21.94 mA/cm² and 24.98 mA/cm² in the case of the anti-reflective layer made from SiO₂ and Al nanoparticles at the top side or inside that, respectively. Finally, using a double anti-reflective layer that is made from SiO₂-TiO₂, the maximum photocurrents of 23.79 mA/cm² and 24.68 mA /cm² are obtained when Al nanoparticles are at the top side or inside that, respectively. The simulation results show that the embedding Al nanoparticles in the anti-reflective layer can improve the photocurrent of a thin-film GaAs solar cell.

     

Synthesis and biological activity of benzo-fused 7-deazaadenosine analogues. 5- and 6-substituted 4-amino- or 4-alkylpyrimido[4,5-b]indole ribonucleosides

Two series of new 4-aminopyrimido[4,5-b]indole ribonucleosides bearing phenyl or hetaryl group at position 5 or 6 have been prepared by Suzuki or Stille cross-coupling reactions employing X-Phos ligand with (het)arylboronic acids or stannanes. A series of 4-substituted nucleosides has been also prepared by Pd-catalyzed cross-couplings or nucleophilic substitution. Some of these compounds displayed moderate antiviral activities against HCV and dengue viruses.     

Identification of a Novel Human Papillomavirus by Metagenomic Analysis of Samples from Patients with Febrile Respiratory Illness

As part of a virus discovery investigation using a metagenomic approach, a highly divergent novel Human papillomavirus type was identified in pooled convenience nasal/oropharyngeal swab samples collected from patients with febrile respiratory illness. Phylogenetic analysis of the whole genome and the L1 gene reveals that the new HPV identified in this study clusters with previously described gamma papillomaviruses, sharing only 61.1% (whole genome) and 63.1% (L1) sequence identity with its closest relative in the Papillomavirus episteme (PAVE) database. This new virus was named HPV_SD2 pending official classification. The complete genome of HPV-SD2 is 7,299 bp long (36.3% G/C) and contains 7 open reading frames (L2, L1, E6, E7, E1, E2 and E4) and a non-coding long control region (LCR) between L1 and E6. The metagenomic procedures, coupled with the bioinformatic methods described herein are well suited to detect small circular genomes such as those of human papillomaviruses.     

Use of Coupled Al-Ag Bimetallic Cylindrical Nanoparticles to Improve the Photocurrent of a Thin-Film Silicon Solar Cell

In this paper, cylindrical shape coupled bimetallic plasmonic nanoparticles (NPs) were used to improve the performance of a thin-film silicon solar cell. Our design is based on the appropriate selection of the composition and morphology of the NPs to reach a cell with excellent optical properties. The specific interaction between the incident light and bimetallic NPs helps us to design better solar absorbers. Here, the FDTD method was used to evaluate the effect of cylindrical Al-Ag bimetallic NPs on the surface of a thin silicon absorber. At first, a unit cell with Al-Al paired nano-cylinders at the surface was evaluated and a photocurrent of 14.65 mA/cm² was obtained. In the case of a cell with paired Al-Ag bimetallic nano-cylinders, the photocurrent was increased to 16.15 mA/cm². This value was increased to 16.57 mA/cm² when paired polymetallic NPs were used. According to the results of this work, bimetallic and polymetallic nanoparticles can significantly improve the photocurrent of an ultra-thin silicon solar cell. The results of this work can be used to design better plasmonic-based light trapping systems for thin-film solar cells.

     

Imaging techniques for the detection of stored product pests

Stored grains are subject to deterioration and losses through various factors, but mainly insects and fungi. Various techniques are employed to detect stored product pests; however, there is an urgent need for an industrial-scale on-line detection technique. Near-infrared hyperspectroscopic imaging and soft X-rays have shown the potential for real-time application. These techniques are particularly effective for detecting internal infestations of stored grains. The digital images of the scanned objects are analyzed for various spectral and image features using statistical techniques such as complex multivariate tools. Classification accuracies as high as 80–100 % have been achieved for various pest and grain combinations. Dual-energy X-rays have been shown to detect the concealed eggs of stored product insect pests. The main threats to stored cereals come from Aspergillus spp., Penicillium spp., and Fusarium spp., which may produce mycotoxins. These imaging techniques have shown good results in the detection of fungal infections of stored grain.     

A dominant negative mutant of protein kinase CK2 exhibits altered auxin responses in Arabidopsis

Protein kinase CK2 is a pleiotropic Ser/Thr kinase, evolutionary conserved in eukaryotes. Studies performed in different organisms, from yeast to humans, have highlighted the importance of CK2 in cell growth and cell-cycle control. However, the signalling pathways in which CK2 is involved have not been fully identified. In plants, the phytohormone auxin is a major regulator of cell growth. Recent discoveries have demonstrated that differential distribution of within auxin plant tissues is essential for developmental processes, and that this distribution is dependent on polar auxin transport. We report here that a dominant-negative mutant of CK2 (CK2mut) in Arabidopsis thaliana shows phenotypic traits that are typically linked to alterations in auxin-dependent processes. However, CK2mut plants exhibit normal responses to exogenous indole-3-acetic acid (IAA) indicating that they are not affected in the perception of the hormone but upstream in the pathway. We demonstrate that mutant plants are not deficient in IAA but are impaired in its transport. Using genetic and pharmacological tools we show that CK2 activity depletion hinders correct formation of auxin gradients and leads to widespread changes in the expression of auxin-related genes. In particular, members of the auxin efflux carrier family (PINs), and the protein kinase PINOID, both key regulators of auxin fluxes, were misexpressed. PIN4 and PIN7 were also found mislocalized, with accumulation in endosomal bodies. We propose that CK2 functions in the regulation of auxin-signalling pathways, particularly in auxin transport.     

SAR studies on dihydropyrimidinone antibiotics

There is an urgent need for the development of novel antimicrobial agents that offer effective treatment against MRSA. Using a new class of dipeptide antibiotic TAN-1057A/B as lead, we designed, synthesized and evaluated analogs of TAN-1057A/B. Several novel dihydropyrimidinone antibiotics demonstrating comparable antibiotic efficacy while possessing favorable selectivity were identified.     

A fluorescence-based alkaline phosphatase-coupled polymerase assay for identification of inhibitors of dengue virus RNA-dependent RNA polymerase

The flaviviral RNA-dependent RNA polymerase (RdRp) is an attractive drug target. To discover new inhibitors of dengue virus RdRp, the authors have developed a fluorescence-based alkaline phosphatase-coupled polymerase assay (FAPA) for high-throughput screening (HTS). A modified nucleotide analogue (2'-[2-benzothiazoyl]-6'-hydroxybenzothiazole) conjugated adenosine triphosphate (BBT-ATP) and 3'UTR-U(30) RNA were used as substrates. After the polymerase reaction, treatment with alkaline phosphatase liberates the BBT fluorophore from the polymerase reaction by-product, BBT(PPi), which can be detected at excitation and emission wavelengths of 422 and 566 nm, respectively. The assay was evaluated by examining the time dependency, assay reagent effects, reaction kinetics, and signal stability and was validated with 3'dATP and an adenosine-nucleotide triphosphate inhibitor, giving IC(50) values of 0.13 μM and 0.01 μM, respectively. A pilot screen of a diverse compound library of 40,572 compounds at 20 μM demonstrated good performance with an average Z factor of 0.81. The versatility and robustness of FAPA were evaluated with another substrate system, BBT-GTP paired with 3'UTR-C(30) RNA. The FAPA method presented here can be readily adapted for other nucleotide-dependent enzymes that generate PPi.     

The effect of Quercus castaneifolia extract on pathogenic enteric bacteria

The family of Enterobacteriaceae is a major group of gram negative bacteria, some of these microorganisms are pathogen and could cause disease mainly gastroenteritis. Recently, due to drug resistant nature of these bacteria specially in developing countries treatment of the patient considered as important investigate. Quercus castaneifolia is a native plant of Yasuj province in Iran, which the people who living in this area consume the fruit of this plant for treatment of enteric disease. Hence, the present study was conducted to evaluate the effect of fruit of Q. castaneifolia extract on pathogenic enteric bacteria viz., E. coli, Salmonella typhimurium, Shigella dysenteriae and Yersinia enterocolitica.Antimicrobial susceptibility and minimal inhibitory concentration (MIC) of the extracts were assessed by gel diffusion method and modification of E-test respectively. All the experiments were performed in triplicate and the statistical analysis was carried out on the results. The results obtained from this study indicated that alcoholic extract was shown antimicrobial effect on the microorganisms tested. In addition, S. dysentriae was more sensitive with zone of inhibition 18 mm and MIC value was 2.5 × 10⁻⁴ whereas, E. coli was less sensitive with zone of inhibition 12 mm and MIC value 1 × 10⁻². Salmonella typhimurium and Yersinia enterocolitica showed relatively intermediate susceptibility to the extract with zone of inhibition of 14 mm and MIC value 5 × 10⁻³. Overall, Q. castaneifolia may be considered for treatment of the patients suffering from enteric disease.