Magnetic wire-based sensors for the micro-rheology of complex fluids

We propose a simple micro-rheology technique to evaluate the viscoelastic properties of complex fluids. The method is based on the use of magnetic wires of a few microns in length submitted to a rotational magnetic field. In this work, the method is implemented on a surfactant wormlike micellar solution that behaves as an ideal Maxwell fluid. With increasing frequency, the wires undergo a transition between a steady and a hindered rotation regime. The study shows that the average rotational velocity and the amplitudes of the oscillations obey scaling laws with well-defined exponents. From a comparison between model predictions and experiments, the rheological parameters of the fluid are determined.Comment: 14 pages 7 figures, accepted in Physical Review

Effect of Soil Moisture Stress on Physiological Response in Grape (Vitis vinifera L.) Varieties

Four varieties of grape namely Flame Seedless, Thompson Seedless, Sharad Seedless and Tas-A-Ganesh were subjected to different levels of moisture stress to study their physiological response. Stress was imposed for 14 days by withholding irrigation. Observations on relative water content, leaf water potential, leaf osmotic potential and gas exchange parameters like photosynthetic rate, transpiration rate, stomatal conductance and water use efficiency (WUE) were recorded. None of the varieties could survive for 14 days without irrigation (100% stress). Flame Seedless and Thompson Seedless at 50% moisture stress maintained higher turgidity as indicated by lesser reduction in relative water content and water potential attributed to better osmotic adjustment. Marginal reduction in photosynthesis and greater reduction in transpiration rate in the variety Flame Seedless may have resulted in higher WUE under moisture stress. Higher photosynthetic rate, lower transpiration rate, higher water relation parameters and high WUE in Flame Seedless under soil moisture stress indicated its better tolerance to drought

Oligomeric state study of prokaryotic rhomboid proteases

AbstractRhomboid peptidases (proteases) play key roles in signaling events at the membrane bilayer. Understanding the regulation of rhomboid function is crucial for insight into its mechanism of action. Here we examine the oligomeric state of three different rhomboid proteases. We subjected Haemophilus influenzae, (hiGlpG), Escherichia coli GlpG (ecGlpG) and Bacillus subtilis (YqgP) to sedimentation equilibrium analysis in detergent-solubilized dodecylmaltoside (DDM) solution. For hiGlpG and ecGlpG, rhomboids consisting of the core 6 transmembrane domains without and with soluble domains respectively, and YqgP, predicted to have 7 transmembrane domains with larger soluble domains at the termini, the predominant species was dimeric with low amounts of monomer and tetramers observed. To examine the effect of the membrane domain alone on oligomeric state of rhomboid, hiGlpG, the simplest form from the rhomboid class of intramembrane proteases representing the canonical rhomboid core of six transmembrane domains, was studied further. Using gel filtration and crosslinking we demonstrate that hiGlpG is dimeric and functional in DDM detergent solution. More importantly co-immunoprecipitation studies demonstrate that the dimer is present in the lipid bilayer suggesting a physiological dimer. Overall these results indicate that rhomboids form oligomers which are facilitated by the membrane domain. For hiGlpG we have shown that these oligomers exist in the lipid bilayer. This is the first detailed oligomeric state characterization of the rhomboid family of peptidases

Distributed optimization for nonrigid nano-tomography

Resolution level and reconstruction quality in nano-computed tomography (nano-CT) are in part limited by the stability of microscopes, because the magnitude of mechanical vibrations during scanning becomes comparable to the imaging resolution, and the ability of the samples to resist beam damage during data acquisition. In such cases, there is no incentive in recovering the sample state at different time steps like in time-resolved reconstruction methods, but instead the goal is to retrieve a single reconstruction at the highest possible spatial resolution and without any imaging artifacts. Here we propose a joint solver for imaging samples at the nanoscale with projection alignment, unwarping and regularization. Projection data consistency is regulated by dense optical flow estimated by Farneback's algorithm, leading to sharp sample reconstructions with less artifacts. Synthetic data tests show robustness of the method to Poisson and low-frequency background noise. Applicability of the method is demonstrated on two large-scale nano-imaging experimental data sets.Comment: Manuscript and supplementary materia

Efficiency of fresh fish and clam meat as a maturation diet in Sebae clownfish, Amphiprion sebae (Bleeker 1853)

107-114The influence of different combinations of fresh fish and clam meat as feed on gonadal development and maturation in Amphiprion sebae was evaluated in a 60-day study. The study used four different combinations of diet viz. control diet (C: commercial feed with 50 % protein (C)), Treatment 1 (T1: fresh fish alone (F)), Treatment 2 (T2: fresh fish in combination with squid meat (FSQ)) and Treatment 3 (T3: fresh fish in combination with clam meat (FCM)). The experiment was conducted in triplicate, with Clown fish (mean weight: 15 g) stocked in tanks of 200 L capacity. The stocked fish were fed on alternate days with the respective assigned diets. On completion of the 60 days study period, maturation of the fish was assessed based on gonado-somatic index (GSI), fecundity and histology. The present study found highest GSI in fish fed with a diet of fresh fish and clam meat on alternate days (0.493 %), followed by fish fed with a diet of fresh fish and squid meat in alternate days (0.349 %) while the lowest GSI was observed in the group fed with the control diet (0.100 %). Average fecundity observed for A. sebae during the present study was 2204±137.4 eggs. Among the different diets, fish fed fresh fish and clam meat (T3) on alternate days had better gonadal development. On 60th day, the ovary of T3 showed late vitellogenic oocytes with an appearance of yolk vesicles. Thus, it could be concluded that fresh fish in combination with clam meat can be used as maturation diet for marine ornamental fish A. sebae to attain early maturation in captivity

Monoclonal antibody-conjugated dendritic nanostructures for siRNA delivery

Small interfering RNA (siRNA) is a promising tool for gene therapy-based disease treatments. However, delivery of siRNA to the target cells requires a specific and reliable carrier system. Herein we describe a targeted carrier system that can deliver siRNA to cancer cells overexpressing the human epidermal growth factor 2 (HER2) receptor. Trastuzumab-conjugated poly(amido)amine dendrimers can be synthesized using the protocols described here

Targeting Glycosylation Pathways and the Cell Cycle: Sugar-Dependent Activity of Butyrate-Carbohydrate Cancer Prodrugs

SummaryShort-chain fatty acid (SCFA)-carbohydrate hybrid molecules that target both histone deacetylation and glycosylation pathways to achieve sugar-dependent activity against cancer cells are described in this article. Specifically, n-butyrate esters of N-acetyl-d-mannosamine (But4ManNAc, 1) induced apoptosis, whereas corresponding N-acetyl-d-glucosamine (But4GlcNAc, 2), d-mannose (But5Man, 3), or glycerol (tributryin, 4) derivatives only provided transient cell cycle arrest. Western blots, reporter gene assays, and cell cycle analysis established that n-butyrate, when delivered to cells via any carbohydrate scaffold, functioned as a histone deacetylase inhibitor (HDACi), upregulated p21WAF1/Cip1 expression, and inhibited proliferation. However, only 1, a compound that primed sialic acid biosynthesis and modulated the expression of a different set of genes compared to 3, ultimately killed the cells. These results demonstrate that the biological activity of butyrate can be tuned by sugars to improve its anticancer properties

Needle(s) in the Haystack – Synchronous Multifocal Tumor Induced Osteomalacia

This is the author accepted manuscript. The final version is available from Endocrine Society via http://dx.doi.org/10.1210/jc.2015-3854MG is supported by the NIHR Cambridge Biomedical Research Centre

Evaluation of the Parasight Platform for Malaria Diagnosis

The World Health Organization estimates that nearly 500 million malaria tests are performed annually. While microscopy and rapid diagnostic tests (RDTs) are the main diagnostic approaches, no single method is inexpensive, rapid, and highly accurate. Two recent studies from our group have demonstrated a prototype computer vision platform that meets those needs. Here we present the results from two clinical studies on the commercially available version of this technology, the Sight Diagnostics Parasight platform, which provides malaria diagnosis, species identification, and parasite quantification. We conducted a multisite trial in Chennai, India (Apollo Hospital [n = 205]), and Nairobi, Kenya (Aga Khan University Hospital [n = 263]), in which we compared the device to microscopy, RDTs, and PCR. For identification of malaria, the device performed similarly well in both contexts (sensitivity of 99% and specificity of 100% at the Indian site and sensitivity of 99.3% and specificity of 98.9% at the Kenyan site, compared to PCR). For species identification, the device correctly identified 100% of samples with Plasmodium vivax and 100% of samples with Plasmodium falciparum in India and 100% of samples with P. vivax and 96.1% of samples with P. falciparum in Kenya, compared to PCR. Lastly, comparisons of the device parasite counts with those of trained microscopists produced average Pearson correlation coefficients of 0.84 at the Indian site and 0.85 at the Kenyan site

Kinetics and Ligand-Binding Preferences of Mycobacterium tuberculosis Thymidylate Synthases, ThyA and ThyX

Mycobacterium tuberculosis kills approximately 2 million people each year and presents an urgent need to identify new targets and new antitubercular drugs. Thymidylate synthase (TS) enzymes from other species offer good targets for drug development and the M. tuberculosis genome contains two putative TS enzymes, a conventional ThyA and a flavin-based ThyX. In M. tuberculosis, both TS enzymes have been implicated as essential for growth, either based on drug-resistance studies or genome-wide mutagenesis screens. To facilitate future small molecule inhibitors against these proteins, a detailed enzymatic characterization was necessary.After cloning, overexpression, and purification, the thymidylate-synthesizing ability of ThyA and ThyX gene products were directly confirmed by HPLC analysis of reaction products and substrate saturation kinetics were established. 5-Fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP) was a potent inhibitor of both ThyA and ThyX, offering important clues to double-targeting strategies. In contrast, the folate-based 1843U89 was a potent inhibitor of ThyA but not ThyX suggesting that it should be possible to find ThyX-specific antifolates. A turnover-dependent kinetic assay, combined with the active-site titration approach of Ackermann and Potter, revealed that both M. tuberculosis enzymes had very low k(cat) values. One possible explanation for the low catalytic activity of M. tuberculosis ThyX is that its true biological substrates remain to be identified. Alternatively, this slow-growing pathogen, with low demands for TMP, may have evolved to down-regulate TS activities by altering the turnover rate of individual enzyme molecules, perhaps to preserve total protein quantities for other purposes. In many organisms, TS is often used as a part of larger complexes of macromolecules that control replication and DNA repair.Thus, the present enzymatic characterization of ThyA and ThyX from M. tuberculosis provides a framework for future development of cell-active inhibitors and the biological roles of these TS enzymes in M. tuberculosis