Human molecular chronotyping in sight?

Orchestration of gene expression and physiology by the circadian clock

In mammals, the master circadian clock that drives many biochemical, physiological and behavioral rhythms is located in the suprachiasmatic nuclei (SCN) of the hypothalamus. Generation and maintenance of circadian rhythms rely on complex interlaced feedback loops based on transcriptional and posttranscriptional events involving clock genes and kinases. This clock serves the purpose to organize an organism's biochemistry on a 24 h time scale thereby avoiding interference between biochemical pathways and optimizing performance. Synchronization to environmental 24 h oscillations tunes physiological processes optimally with nature. In this review, I briefly describe the principle of the clock mechanism, its synchronization to the environment and consequences on health when the circadian clock is disrupted.

Early onset of regionalization in EMS lineage of C. elegans embryo: a quantitative study

Early localization of C. elegans founder cell descendents in certain regions of embryo has been documented. The purpose of this investigation is to evaluate the onset of ABp and EMS descendent cell regionalization in the embryo using the random motility coefficient as a quantitative parameter. The forward migration index (FMI) was also calculated in order to evaluate the chemotatic biases of ABp-dc and EMS-dc during regionalization. The results showed that the random motility coefficient declined as the cells tended to regionalize. The mean squared displacement (MSD) versus time plot showed a non-linear model which indicated non-random cell movement. FMI showed progressive increase as the cells tended to regionalized, and it was significantly higher in EMS-dc than ABp-dc, moreover the chemotatic biases were higher in EMS-dc than ABp-dc. The circular plots showed that the statistical differences between the two lineages were significant, while ABp-dc showed significant differences in xy, xz and yz planes; EMS derived cells showed no significant differences except in yz planes. The conclusion of this study is that the onset of early regionalization occurs in EMS-dc sooner than in ABp-dc.