EAWAG news 56e (November 2003)
Molecules in Action (Entire Volume)
| Editorial: From Ecosystem via Molecule to Ecosystem |
| (Screenversion ca. 85 KB; Printversion 100 KB) |
| Rik Eggen |
| Lead Article |
| Molecular Strategies in the Environment
- 135 Years of Spell-Binding Research (Screenversion 210 KB; Printversion 540 KB) Alexander Zehnder Since the middle of the last century, molecular biology is its own discipline. It has its roots in microbiology, a discipline traditionally examining life processes and the role of microorganisms in different ecosystems. While today’s applications of molecular biology in biotechnology and in the medical field are widely known, molecular approaches to problem-oriented environmental research are still very much in the background. This is not justified since these techniques are highly useful in the solution of current problems. |
| Research Reports |
| Genomic Islands and Horizontal
Gene Transfer Among Bacteria (Screenversion 185 KB; Printversion 515 KB) Jan Roelof van der Meer Chromosomes are usually thought to be stable molecules, which have to be copied carefully for each of the new daughter cells. Except for a few copying mistakes (“mutations”), not much is happening to the chromosomal DNA. Or is it? Bacterial chromosomes are now known to harbor what is called “genomic islands”, regions which can cut themselves out of the chromosome, in some cases travel to other bacterial cells and reinsert into the recipient’s chromosome. Their function? Very often, they provide the recipient bacteria with auxiliary capabilities for infecting eukaryotic hosts or for degrading environmental pollutants. |
| Characterization of Reactive Chemicals
Based on their Primary Mode of Action (Screenversion 145 KB; Printversion 220 KB) Beate Escher Dead fish washed on the shore “belly up”: who has not seen these pictures? They illustrate dramatically the fatal effects on aquatic life that accidents with environmental pollutants can have. However, our environment is also continuously influenced by chemical pollutants in low concentrations which unfortunately remain unperceived in most cases. It is important therefore to find out how exactly pollutants react in organisms. Thus, the goal of our research is to identify and classify the various primary modes of action of reactive chemicals by means of a bacterial test system. |
| Bacterial Biosensors to Measure
Arsenic in Potable Water (Screenversion 250 KB; Printversion 795 KB) Jan Roelof van der Meer Worldwide, arsenic is one of the most important inorganic pollutants in drinking water. Particularly alarming is the situation in Bangladesh where more than one million people are already suffering from arsenic poisoning. In order to test each one of the roughly 9 million private drinking water wells, an inexpensive, reliable and sensitive field method is needed. For this reason, an EAWAG team has developed a new biosensor for arsenic. The paper strip test uses genetically modified bacteria that produce blue coloration even at low arsenic concentrations. EAWAG has applied for a patent for this sensor. |
| Defense Genes as Indicators of
Toxicity (Screenversion 250 KB; Printversion 700 KB) Beat Fischer As a result of exposure to certain pollutants, various toxic oxygen derivatives form in the cells of plants and animals, including the so-called “singlet oxygen”. Fortunately, most cells have specific defense mechanisms against the toxic effects of these derivatives. Currently, research at EAWAG is examining in detail how the unicellular green alga Chlamydomonas reinhardtii reacts to the presence of singlet oxygen. The long-term goal of the work is to develop a biosensor for the detection of singlet oxygen, which would give us an indirect indicator of pollutant levels. |
| New Paths in the Analysis of Drinking
Water Quality (Screenversion 130 KB; Printversion 170 KB) Annette Rust Drinking water is routinely tested for the presence of bacteria by culturing methods which have the disadvantage of being very time consuming. It takes at least one day before results are available. For this reason, EAWAG is currently developing a faster method. The application of new molecular techniques is promising, although the development of an actual method is proving to be rather difficult. |
| The Anammox Process for Nitrogen
Removal from Waste Water (Screenversion 155 KB; Printversion 305 KB) Christian Fux As a country bordering the Rhine, Switzerland shares in the responsibility to reduce nitrogen export to the North Sea. In wastewater treatment plants, this is currently accomplished through a costly expansion of the main activated sludge system. During the 1990s, however, there were several reports of nitrogen being eliminated rather unexpectedly under certain operating conditions. It was found that this is due to a recently discovered group of bacteria, which were also found in Swiss wastewater treatment plants. Based on this discovery, process engineers have developed a new process that reliably removes nitrogen. |
| Genetic Diversity of Daphnia in
Alpine Lakes (Screenversion 145 KB; Printversion 210 KB) Monika Winder, Piet Spaak The diversity of zoo- and phytoplankton in alpine lakes has been studied intensively for over 100 years. It is now generally accepted that the species diversity of plankton communities decreases with increasing altitude. This study addresses the question as to whether or not this general pattern also applies at the population level. Daphnia, a typical member of zooplankton communities, was chosen as the study organism. Genetic diversity was determined for 11 Daphnia populations in mountain lakes at varying elevations. We found that the genetic diversity was very heterogeneous. |
| In Brief (Screenversion 140 KB; Printversion 480 KB) |
Please feel free to submit questions or suggestions any time to the editor Martina Bauchrowitz.