The versatile transcription factor Oct-1 : a crucial protein in embryonic development and a key component of the stress cellular response

Oct-1 is a transcription factor belonging to the POU family (Clerc et al. 1988) (Herr et al. 1988) (Ryan and Rosenfeld 1997). The members of this family are involved in a broad range of biological processes like transcription of housekeeping genes (Oct-1), pluripotency of embryonic stem cells (Oct-4) or development of immune system (Oct-1, Oct-2) (Spaniol et al. 1996). The transcription factor Oct-1 is ubiquitously expressed in embryonic and adult tissues, and regulates the expression of a variety of genes. Previous studies described Oct-1 to be regulated at the protein level by phosphorylation in a cell cycle dependent manner. In addition, more recently it has been shown that Oct- 1 is induced in response to DNA damage and modulates the activity of genes like GADD45 important for the cellular stress response (Segil et al. 1991) (Zhao et al. 2000) (Jin et al. 2001) (Fan et al. 2002) (Tantin et al. 2005).. Knockout and a conditional oct-1 knockout alleles were created in our laboratory, and used to generate Oct-1 deficient mouse embryonic fibroblast (MEFs) and embryonic stem cells (ES). We used them as a model to study the cellular response to stress in absence of Oct-1. We have found that cells lacking Oct-1 were less sensitive to stress lik

Theoretical Development of the Differential Scattering Decomposition for the 3D Resistivity Experiment

In any numerical solution of the DC resistivity experiment, care must be taken to deal with strong heterogeneity of electrical conductivity. In order to examine the importance of conductivity contrasts, we develop a scattering decomposition of the DC resistivity equation in the sparse differential domain as opposed to the traditional dense integral formulation of scattering-type equations. We remove the singularity in the differential scattered series via separation of primary and secondary conductivity, thereby avoiding the need to address the singularity in a Green\u27s function. The differential scattering series is observed to diverge for large conductivity contrasts and to converge for small contrasts. We derive a convergence criterion, in terms of matrix norms for the weak-form finite-volume equations, that accounts for both the magnitude and distribution of heterogeneity of electrical conductivity. We demonstrate the relationship between the differential scattering series and the Fréchet derivative of the electrical potential with respect to electrical conductivity, and we show how the development may be applied to the inverse problem. For linearization associated with the Fréchet derivative to be valid, the perturbation in electrical conductivity must be small as defined by the convergence of the scattered series. The differential scattering formulation also provides an efficient tool for gaining insight into charge accumulation across contrasts in electrical conductivity, and we present a derivation that equates accumulated surface charge density to the source of scattered potential

Effect of Oral Creatine Supplementation on Single-Effort Sprint Performance in Elite Swimmers

Oral supplementation with creatine monohydrate (Cr.H2O) has been reported to increase muscle creatine phosphate levels. The aim of the present study was to determine the effect of such supplementation on performance of a single-effort sprint by elite swimmers. Thirty-two elite swimmers (M = 18, F = 14; age = 17-25 years) from the Australian Institute of Sport were tested on two occasions, 1 week apart. Tests performed were 25-m, 50-m, and 100-m maximal effort sprints (electronically timed with dive start, swimmers performing their best stroke), each with approximately 10 min active recovery. A 10-s maximal leg ergometry test was also undertaken. Swimmers were divided into two groups matched for sex, stroke/event, and sprint time over 50 m, and groups were randomly assigned to 5 days of Cr.H2O supplementation (4 · day-1 × 5 g Cr.H2O + 2 g sucrose, n = 16) or placebo (4 · day-1 × 5 g Polycose + 2 g sucrose, n = 16) prior to the second trial. Results revealed no significant differences between the group means for sprint times or between 10-s maximal leg ergometry power and work. This study does not support the hypothesis that creatine supplementation enhances single-effort sprint ability of elite swimmers.</p