Unity and Diversity of Responses to Xenobiotics in Organisms

A conceptual treatment of the mechanisms involved in the process of toxicosis by diverse agents in different tissues indicate a likely unspecific, common, central process in addition to specific precipitating factors acting on a particular site in a cascade of events. Free radicals, membrane functions and calcium functions appear to be links in the common pathway. Such a central mechanism could be interrelated with immunological defenses as well as genotoxic changes at different sites, suggesting parallel or related evolution of these antistress mechanisms. Many radical scavengers, antioxidants, membrane stabilizers, nutritional supplements and calcium modulators have proved beneficial either in reducing toxic impact, delaying the development of lesions or even reversing the effects. Similarly, recent evidences show that some immunomodulators can act as antioxidants and antigenotoxicants. Thus, the status of body defenses which may vary from one individual to the other have a role in deciding the effects under the same quantified risks with varying relative responses. Whether modulation of physiological defenses against stress could help in developing prophylactic measures remains an open question.

Species and Organ Diversity in the Effects of Hydrogen Peroxide on Superoxide Dismutase Activity In Vitro

Superoxlde dlsmutase （SOD） is ubiquitous in aerobic organisms and constitutes the first link In the enzyme scavenging system of reactive oxygen species. In the present study, species and organ diversity of SOD activity In a solution and In an in-gel assay system, as well as the effects of hydrogen peroxide （H202） on SOD activity, were Investigated. In a solution assay system, SOD activity of jackfruIt root, shoot, leaves, axes, and cotyledons, of maize embryos and endosperms, of mung bean leaves and seeds, of sacred lotus axes and cotyledons, and of rice and wheat leaves was Increased by 1-15 mmol/L H2O2. However, SOD activity In rice root and seeds, maize roots and leaves, mung bean roots and shoots, and wheat seeds was decreased by 1-15 mmol/L H2O2. The SOD activity of wheat root and soybean roots, leaves, axes, and cotyledons was Increased by 1-4 mmol/L H2O2, but was decreased by concentrations of H2O2 〉4 mmol/L. The SOD activity of soybean shoots was not affected by 1-15 mmol/L H2O2. The SOD activity In crude mltochondrla of jackfruIt, maize, and upas seeds, as well as In purified mitochondria of jackfruIt, was also Increased by 1-15 mmol/L H2O2. In the In-gel assay system, the SOD In jackfruIt cotyledons was comprised of Mn-SOD, Cu/Zn-SOD, and Fe-SOD, the crude mltochondria of jackfruit seeds and maizes embryo was comprised of Mn-SOD and Cu/ Zn-SOD, and the crude mltochondria of maize seeds was comprised of Mn-SOD only. In the present study, H2O2 markedly Inhibited Cu/Zn-SOD and Fe-SOD activity.

The genome-wide molecular regulation of mouse gastrulation embryo

The diverse morphologies among vertebrate species stems from the evolution of a basic body plan that is constituted by a spatially organized ensemble of tissue lineage progenitors. At gastrulation, this body plan is established through a coordinated morphogenetic process and the delineation of tissue lineages that are driven by the activity of the genome. To explore the molecular mechanisms, in a comprehensive context, it is imperative to glean an understanding of the region-and population-specific genetic activity underpinning this fundamental developmental process. In this review, we outline the recent progress and the future directions in studies of genome activity for the regulation of mouse embryogenesis at gastrulation.