A new minimal mathematical model of the endocrine system of normal rats validated against experimental data

As a common laboratory practice, rats are studied as biological models for understanding human physiology. Even though, with the advent of modern computer sciences, new methodologies appeared in medical sciences like simulation and optimization to simplify and improve the experimental work. With this background, a novel simulation model of the endocrine system of Sprague Dawley rats is presented. It is a simplified mathematical model composed of 3 differential equations and 8 parameters that have been determined and validated with experimental measures of plasma glucose and insulin alone by means of calculus and optimization techniques. The results presented here are a step before the development of a type I diabetic model of Sprague Dawley rats.Sociedad Argentina de Informática e Investigación Operativ

On Refinements of Boolean and Parametric Modal Transition Systems

We consider the extensions of modal transition systems (MTS), namely Boolean MTS and parametric MTS and we investigate the refinement problems over both classes. Firstly, we reduce the problem of modal refinement over both classes to a problem solvable by a QBF solver and provide experimental results showing our technique scales well. Secondly, we extend the algorithm for thorough refinement of MTS providing better complexity then via reductions to previously studied problems. Finally, we investigate the relationship between modal and thorough refinement on the two classes and show how the thorough refinement can be approximated by the modal refinement

Activation of H+-ATPase of the Plasma Membrane of Saccharomyces cerevisiae by Glucose: The Role of Sphingolipid and Lateral Enzyme Mobility

Activation of the plasma membrane H+-ATPase of the yeast Saccharomyces cerevisiae by glucose is a complex process that has not yet been completely elucidated. This study aimed to shed light on the role of lipids and the lateral mobility of the enzyme complex during its activation by glucose. The significance of H+-ATPase oligomerization for the activation of H+-ATPase by glucose was shown using the strains lcb1-100 and erg6, with the disturbed synthesis of sphyngolipid and ergosterol, respectively. Experiments with GFP-fused H+-ATPase showed a decrease in fluorescence anisotropy during the course of glucose activation, suggesting structural reorganization of the molecular domains. An immunogold assay showed that the incubation with glucose results in the spatial redistribution of ATPase complexes in the plasma membrane. The data suggest that (1) to be activated by glucose, H+-ATPase is supposed to be in an oligomeric state, and (2) glucose activation is accompanied by the spatial movements of H+-ATPase clusters in the PM

Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions