Do ionic currents play a role in the control of development?

Painlevé-integrability of a (2+1)-dimensional reaction-diffusion equation: exact solutions and their interactions

We investigate the singularity structure analysis of a (2+1)-dimensional coupled nonlinear extension of the reaction-diffusion (NLERD) equation by means of the Painlevé (P) test. Following the Weiss et al.'s formalism [J. Math. Phys. 24, 522 (1983)], we prove the arbitrariness of the expansion coefficients of the observables. Thus, without the use of the Kruskal's simplification, we obtain a Bäcklund transformation of the coupled NLERD equation via a consistent truncation procedure stemming from the Weiss 's methodology [J. Weiss, M. Tabor, and G. Carnevale, J. Math. Phys. 25, 13 (1984)]. In the wake of such results, we unveil a typical spectrum of localized and periodic coherent patterns. We also investigate the scattering properties of such structures and we unearth two peculiar soliton phenomena, namely, the fusion and the fission.

Bioelectromagnetics in morphogenesis

Understanding the factors that allow biological systems to reliably self-assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration.

Non-invasive monitoring of ionic current flow during development by SQUID magnetometry

The ionic currents flowing in developing organisms produce weak magnetic fields that can be detected using SQUID magnetometers. The method is non-invasive and dc recording is possible. To date SQUID magnetometers have mainly been used in human studies. The features of the technique are described and the prospects of extending its use to developmental studies are discussed. Feasible instrumental specifications are indicated. A recent SQUID magnetometer investigation of ionic current flow in the developing chick in ovo is summarised as an illustration of the magnetometer method. The paper as a whole argues that magnetometry is a useful alternative or adjunct to electrode-based experiments on the electrophysiology of developing organisms.

Superoxide dismutase activity and glutathione concentration during the calcium-induced differentiation of Physarum polycephalum microplasmodia

Microplasmodia of Physarum polycephalum differentiate into spherules when the CaCl2 concentration of their nutrient medium is increased to 54mM (high-calcium). The salts starvation medium routinely used to induce differentiation contains 8mM CaCl2. This medium will not induce spherulation in the absence of a calcium salt; no other metal is essential. High-calcium also induces the spherulation of a strain of Physarum that had not been previously observed to spherulate. The striking increase in superoxide dismutase activity (SOD) and the decrease in glutathione concentration (GSH) that are characteristic of salts-induced spherulation do not occur in salts media containing high-calcium. In the absence of calcium, no significant change in SOD is observed and very little change in GSH occurs. The immediate effect of the oxidative stress associated with spherulation may be the release of calcium stores into the cytosol. The parameters modulating this stress are, in turn, sensitive to exogenous calcium concentrations.