Expression of angiotensin II AT2 receptors in the rat skin during experimental wound healing.

We localized and characterized angiotensin II AT1 and AT2 receptors in the skin of 2-week-old rats during experimental wound healing. Both AT1 and AT2 were present in the skin. Three days after wounding, the expression of angiotensin II receptors was significantly enhanced in the dermis as well as in a localized band within the superficial dermis of the skin surrounding the wound. The major proportion of this increase was due to angiotensin II AT2 receptors. Our results suggest a physiological role for AT2 receptors in the process of tissue repair.     

Reaction kinetics of d-glucose fermentation by Saccharomyces cerevisiae

Data obtained on the conversion of d-glucose to alcohol using Saccharomyces cerevisiae in batch culture has been analysed kinetically. The effects of different kinetic parameters, e.g. rates of ethanol and biomass formation, rate of d-glucose utilization and variation of pH have been studied. Analysis of data was made on the basis of Michaelis-Menten, Leudeking-Piret and simple kinetics. Unsteady rate behaviour in the lag phase was observed and explained.     

A comparative study of the effects of aflatoxin B1, alpha-amanitin and actinomycin-D on RNA synthesis by rat liver.

The effect of different combinations of aflatoxin B1, alpha-amanitin and actinomycin-D on the incorporation of orotic acid-6-14C into RNA was investigated using rat liver slices. The results support the view that the mode of action of aflatoxin B1 and alpha-amanitin are similar in some respects, and that aflatoxin B1 and actinomycin-D act according to different mechanisms. Evidence was also obtained about the formation of an active metabolite of aflatoxin B1 in this system.     

Mitochondrial damage by active oxygen species in vitro

Under in vitro conditions involving formation of active oxygen species, rat liver mitochondria were found to undergo swelling, peroxidative decomposition of lipids, and distinct disorganization of ultrastructure. Supplementation with free radical scavengers such as superoxide dismutase (SOD), methionine, histidine, and tryptophan accorded considerable protection to the organelle. A possible correlation between oxygen radicals, membrane integrity, and calcium functions is indicated.     

The Role of the Epigenome in Gene Expression Control and the Epimark Changes in Response to the Environment

Our knowledge base involving the biochemical participants of epigenetic control has expanded greatly over the last decade. The role of epigenetic marks to DNA and histones controlled by non-coding RNAs is one of the most intensely studied areas of biology today. This review covers many of the mechanisms that non-coding RNAs and other molecules use to control gene expression and eventually affect responses to the environment. In the first part of the review, we discuss the array of covalent modifications to the genome that constitute the epigenome, which consists of the histone variants, covalent modifications, and post-translational modifications that result in gene expression changes. How the histone variants and post-translational modifications including, acetylation, methylation, phosphorylation, ubiquitination and sumoylation help form the epigenome is also summarized. Our eventual understanding of how the environment controls these modifications will open incredible opportunities in agriculture, medicine and the development of practical tools for biology. In the second part of this review we discuss the growing list of environmentally-mediated epigenetic modifications, and examples of transgenerational epigenetic inheritance events, that may begin to change our views of adaptive responses to the environment and evolution.     

Thiol Metabolism and Redox Regulation of Cellular Functions. Series I: Life and Behavioural Sciences

α,β-Unsaturated carbonyl compounds have been implicated in a number of environmentally-related diseases. Often, the presence of α,β-unsaturated carbonyl functionality as part of either an aliphatic or cyclic structure is considered a structural alert for cytotoxicity. We examined the cytotoxicity of methyl vinyl ketone (MVK), an aliphatic, straight-chain α,β-unsaturated carbonyl compound, in murine GT1-7 hypothalamic neurons. In addition to its widespread environmental occurrence, MVK was selected due to its extensive use in the chemical industry. Also, MVK is a close structural analog of hydroxymethylvinyl ketone that, in part, mediates the cytotoxic effects of 1,3-butadiene in vivo. It was found that MVK at low micromolar concentrations induced extensive cell death that retained key features of apoptosis such as chromatin condensation and DNA fragmentation. The MVK-induced apoptosis was associated with depletion of glutathione, disruption of mitochondrial transmembrane potential, and increased generation of reactive oxygen species (ROS). Supplementation of neuronal cells with Trolox offered partial, but significant, protection against the MVK-induced cytotoxicity, presumably due to scavenging of ROS in situ. The suggested sequence of events in the MVK-induced apoptosis in neuronal cells involves the depletion of cellular glutathione followed by an increased generation of ROS and finally the loss of mitochondrial function.