New advances in nano sciences open the door for scientists to study biological processes on a microscopic molecule-by-molecule basis. Recent single-molecule biophysical experiments on enzyme systems, in particular, reveal that enzyme molecules behave fundamentally differently from what classical model predicts. A stochastic network model was previously proposed to explain the experimental disco...

The pattern of DNA methylation plays an important role in regulating different genome functions. To test the hypothesis that DNA methylation is a reversible biochemical process, we purified a DNA demethylase from human cells that catalyzes the cleavage of a methyl residue from 5-methyl cytosine and its release as methanol. We show that similar to DNA methyltransferase, DNA demethylase shows CpG...

Heavy metals are introduced into aquatic ecosystems from industrial wastes, agricultural runoff and mining activities. The toxicity of heavy metal ions in solution to microalgae is well known. The essentiality and toxicity of heavy metals has been a subject of extensive research (Stokes 1983). From a biological point of view, heavy metals can be divided into two categories: essential and non-es...

The use of organofluorine compounds has increased throughout this century, and they are now ubiquitous environmental contaminants. Although generally viewed as recalcitrant because of their lack of chemical reactivity, many fluorinated organics are biologically active. Several questions surround their distribution, fate, and effects. Of particular interest is the fate of perfluoroalkyl substitu...

The halobacteria and the photosynthetic members of the eubacteria have previously been classified in two separate urkingdoms--the archaebacteria and the eubacteria, respectively. They were thought to be no more closely related to each other than they each were to the eukaryotes. In accord with this earlier classification, photosynthesis was thought to have originated twice by independent events...

Circadian rhythms are biological processes displaying endogenous and entrainable oscillations of about 24 h. In mammals the sleep/wake cycle, core body temperature fluctuation, and diurnal variation of blood pressure and heart rate are among the most well-known circadian rhythms. These rhythms are not just the consequence of activity/rest cycles, but are also controlled by molecular clocks, a b...

X-ray fibre-diffraction studies indicate a high degree of stereochemical specificity in interactions between water and the DNA double helix. Evidence for this comes from data that show that the molecular conformations assumed by DNA in fibres are highly reproducible and that the hydration-driven transitions between these conformations are fully reversible. These conformational transitions are i...

DNA is traditionally seen as a linear sequence of instructions for cellular functions that are expressed through biochemical processes. Cellular DNA, however, is also organized as a complex hierarchical structure with a mosaic of mechanical features, and a growing body of evidence is now emerging to imply that these mechanical features are connected to genetic function. Mechanical tension, for ...

Aerobic sludge digestion in the presence of Fenton's reagent and hydrogen peroxide was examined. Fenton's reagent considerably improved the aerobic digestion process in comparison with hydrogen peroxide as well as classical aerobic digestion. Application of Fenton's reagent also led to improvement of settling and dewatering properties of sludge and much better clarity of supernatant. Its drawba...

Complex phenotypes are known to be associated with interactions among genetic factors. A growing body of evidence suggests that gene-gene interactions contribute to many common human diseases. Identifying potential interactions of multiple polymorphisms thus may be important to understand the biology and biochemical processes of the disease etiology. However, despite the great success of genome...