A framework for quantification and physical modeling of cell mixing applied to oscillator synchronization in vertebrate somitogenesis

In development and disease, cells move as they exchange signals. One example is found in vertebrate development, during which the timing of segment formation is set by a ‘segmentation clock’, in which oscillating gene expression is synchronized across a population of cells by Delta-Notch signaling. Delta-Notch signaling requires local cell-cell contact, but in the zebrafish embryonic tailbud, oscillating cells move rapidly, exchanging neighbors. Previous theoretical studies proposed that this relative movement or cell mixing might alter signaling and thereby enhance synchronization. However, it remains unclear whether the mixing timescale in the tissue is in the right range for this effect, because a framework to reliably measure the mixing timescale and compare it with signaling timescale is lacking. Here, we develop such a framework using a quantitative description of cell mixing without the need for an external reference frame and constructing a physical model of cell movement based on the data. Numerical simulations show that mixing with experimentally observed statistics enhances synchronization of coupled phase oscillators, suggesting that mixing in the tailbud is fast enough to affect the coherence of rhythmic gene expression. Our approach will find general application in analyzing the relative movements of communicating cells during development and disease.Fil: Uriu, Koichiro. Kanazawa University; JapónFil: Bhavna, Rajasekaran. Max Planck Institute of Molecular Cell Biology and Genetics; Alemania. Max Planck Institute for the Physics of Complex Systems; AlemaniaFil: Oates, Andrew C.. Francis Crick Institute; Reino Unido. University College London; Reino UnidoFil: Morelli, Luis Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; Argentina. Max Planck Institute for Molecular Physiology; Alemania. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Investigations on Antibacterial Activity of Leaf Extracts of \u3cem\u3eAzadirachta indica\u3c/em\u3e A. Juss (Meliaceae): A Traditional Medicinal Plant of India

The present study was carried out to screen and evaluate antimicrobial activity of leaf extracts of Azadirachta indica A. Juss. Petroleum ether, dichloromethane, chloroform, ethanol and aqueous extract of leaves of A. indica were tested against selected Gram positive and Gram negative bacterial species. Phytochemical leaf extracts of A. indica exhibited significant anti-bacterial activity against all the test microorganisms. However, inhibitory activities of the leaf extracts were both organism and solvent dependent. The leaf extracts limited the growth of both Gram-positive and Gram-negative bacterial species tested. Among the different extracted used in the study, ethanolic and dichloromethane leaf extracts of A. indica were found to be more active towards the bacterial species used in the study. Further, the aqueous leaf extract was moderately active. However, petroleum ether and chloroform extracts were not effective against any of the organisms tested, but for Bacillus cereus where the chloroform extract was moderately active. Growth of Lactobacillus bulgaris was not inhibited by any of the tested leaf extracts of A. indica but for dichloromethane. The study shows that ethanolic and dichloromethane leaf extracts of A. indica can be used as a potential source of antimicrobial agents

Double Threefold Degeneracies for Active and Sterile Neutrinos

We explore the possibility that the 3 active (doublet) neutrinos have nearly degenerate masses which are split only by the usual seesaw mechanism from 3 sterile (singlet) neutrinos in the presence of a softly broken $A_4$ symmetry. We take the unconventional view that the sterile neutrinos may be light, i.e. less than 1 keV, and discuss some very interesting and novel phenomenology, including a connection between the LSND neutrino data and solar neutrino oscillations.Comment: 8 pages, no figur

See-saw fermion masses in an SO(10) GUT

In this work we study an SO(10) GUT model with minimum Higgs representations belonging only to the 210 and 16 dimensional representations of SO(10). We add a singlet fermion S in addition to the usual 16 dimensional representation containing quarks and leptons. There are no Higgs bi-doublets and so charged fermion masses come from one-loop corrections. Consequently all the fermion masses, Dirac and Majorana, are of the see-saw type. We minimize the Higgs potential and show how the left-right symmetry is broken in our model where it is assumed that a D-parity odd Higgs field gets a vacuum expectation value at the grand unification scale. From the renormalization group equations we infer that in our model unification happens at 10^{15} GeV and left-right symmetry can be extended up to some values just above 10^{11} GeV. The Yukawa sector of our model is completely different from most of the standard grand unified theories and we explicitly show how the Yukawa sector will look like in the different phases and briefly comment on the running of the top quark mass. We end with a brief analysis of lepton number asymmetry generated from the interactions in our model.Comment: 30 pages, 10 figure

Evaluation of Serological Markers with Nucleic Acid Based Assay in Diagnosis of Hepatitis C Virus Infection among Chronic Kidney Disease patients in a Tertiary Care Hospital

INTRODUCTION: HCV is the major cause of non-A non-B hepatitis. HCV is endemic in most parts of the world. The global prevalence of Hepatitis C virus (HCV) infection is around 3%. Three to four million people are newly infected every year worldwide. HCV is one of the major cause of transfusion associated acute hepatitis. Infected persons serve as major source for transmission. They are at more risk for developing chronic liver disease, which may progress to cirrhosis and primary hepatocellular carcinoma. HCV is a major cause of liver disease in patients with Chronic kidney disease (CKD) on maintenance hemodialysis. The prevalence of HCV infection among CKD patients is much higher when compared to the general population. Risk factor for spread includes history of transfusion, amount of blood products transfused, and duration of hemodialysis therapy. MATERIALS AND METHODS: A total of 82 patients diagnosed with CKD at our Nephrology Unit were included in the study. After obtaining informed consent from the patients who were enrolled for this study, epidemiological data were collected. All the patients were tested for HCV by anti-HCV antibody detection by third generation ELISA, Combined -HCV antibody and Capsid antigen detection by ELISA, and Real time PCR. RESULTS: Mean age of the CKD patients in our study group was 35.82. More than two third of the CKD patients in our study were male. In our study Hypertension and Diabetes mellitus were the commonly associated conditions in CKD patients In our study 7 patients were tested positive for HCV by antibody ELISA(8.53%), 9 patients were tested positive for HCV by antigen- antibody combined ELISA (10.97%). 11 were tested positive for HCV by PCR (13.41%). Prevalence of HCV in our study group was 13.41%. 11 patients who were tested positive for HCV in our study underwent hemodialysis for more than 24 months. Out of 27 patients who had change of dialysis centre 9 were tested positive for HCV. Prevalence of HCV in our study group was 13.41%. HCV antibody ELISA had sensitivity of 63.63% and specificity of 100% when compared with gold standard PCR. HCV combined antigen-antibody ELISA had sensitivity of 81.81% and specificity of 100% when compared with gold standard PCR.Positive predictive value of HCV antibody ELISA was 100% where as negative predictive value was 94.66%. Positive predictive value of HCV combined antigen-antibody ELISA was 100% where as negative predictive value was 97.26%. CONCLUSION: Adopting universal precautions in hospital and health care settings prevents the nosocomial spread of HCV. In CKD patients with poor immune response antibody ELISA alone is not sufficient for diagnosis of HCV infection. Combined antigenantibody ELISA can be substituted as a diagnostic test where nucleic acid testing facilities are unavailable

Free Radical Scavenging, Cytotoxic and Hemolytic Activities from Leaves of Acacia nilotica (L.) Wild. ex. Delile subsp. indica (Benth.) Brenan

Dietary intake of phytochemicals having antioxidant activity is associated with a lower risk of mortality from many diseases. Therefore, the aim of this study was to determine the free radical scavenging, cytotoxic and hemolytic activities of leaves of Acacia nilotica by using various methods. The results of the present study revealed that ethanol extract was the most effective and IC50 value was found to be 53.6 μg mL−1 for Vero cell lines and 28.9 μg mL−1 for Hela cell lines in cytotoxicity assays. The zone of color retention was 14.2 mm in β-carotene bleaching assay, which was as significant as positive control, butylated hydroxy toluene. None of the tested extracts possessed any hemolytic activity against rat and human erythrocytes revealing their cytotoxic mechanism and non-toxicity. Thus, only the ethanol extract could be considered as a potential source of anticancer and antioxidant compounds. Further phytochemical studies will be performed for specification of the biologically active principles

Reducing False-Positive Prediction of Minimotifs with a Genetic Interaction Filter

Background: Minimotifs are short contiguous peptide sequences in proteins that have known functions. At its simplest level, the minimotif sequence is present in a source protein and has an activity relationship with a target, most of which are proteins. While many scientists routinely investigate new minimotif functions in proteins, the major web-based discovery tools have a high rate of false-positive prediction. Any new approach that reduces false-positives will be of great help to biologists. Methods and Findings: We have built three filters that use genetic interactions to reduce false-positive minimotif predictions. The basic filter identifies those minimotifs where the source/target protein pairs have a known genetic interaction. The HomoloGene genetic interaction filter extends these predictions to predicted genetic interactions of orthologous proteins and the node-based filter identifies those minimotifs where proteins that have a genetic interaction with the source or target have a genetic interaction. Each filter was evaluated with a test data set containing thousands of true and false-positives. Based on sensitivity and selectivity performance metrics, the basic filter had the best discrimination for true positives, whereas the node-based filter had the highest sensitivity. We have implemented these genetic interaction filters on the Minimotif Miner 2.3 website. The genetic interaction filter is particularly useful for improving predictions of posttranslational modifications such as phosphorylation and proteolytic cleavage sites

Radiative stability of neutrino-mass textures

Neutrino-mass textures proposed at high-scales are known to be unstable against radiative corrections especially for nearly degenerate eigen values. Within the renormalization group constraints we find a mechanism in a class of gauge theories which guarantees reproduction of any high-scale texture at low energies with radiative stability. We also show how the mechanism explains solar and atmospheric neutrino anomalies through the bimaximal texture at high scale.Comment: 4 pages REVTEX, 1 Postscript fi

Studies on the Impact of Altitudinal Gradient on Ammonium Assimilatory Metabolism in Glycine max L. (Fabaceae)

Seedlings of Glycine max L. were grown, transplanted and acclimatized for 60 days at different altitudes (250, 400 and 1600 m). Response to shift in altitude was observed in the plants. Shoot length decreased with the increase in the altitude, while root length followed a reverse trend. Biomass accumulation in shoot and roots of G. max was the maximum at high altitude. Total soluble protein content was significantly high at low altitude in the shoot and the roots. Free tissue ammonia level in this species showed positive correlation with increasing altitude. Ammonium assimilatory enzymes viz., glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) were studied. GS/ GOGAT specific and total activity were altitude sensitive, whereas GDH activity exhibited inverse trend. Results indicate that there is a positive shift in ammonium assimilatory pathway in plants growing at high altitude