Although a number of new antibiotics have been discovered in recent decades, our armory against infection is continually being depleted, as our microscopically small enemies are crafty warriors that develop resistance to current antibiotics.
Multiresistant bacteria are a big problem, especially in hospitals. Already weakened patients are easy victims, for which an infection that cannot be treated with antibiotics can quickly become life-threatening. What is needed are active agents that act on completely different sites in the physiological sequence of pathogens than current medicaments. Platensimycin, recently isolated from the mushroom Streptomyces platensis, is such an agent. A Californian team of researchers is now the first to synthesize this natural product completely in the laboratory—a crucial step on the way to a new class of antibiotics.
Platensimycin inhibits an important step of bacterial fatty acid biosynthesis and in this way paralyzes a broad spectrum of Gram-positive bacterial strains. Thus, this natural product in able to kill dangerous germs that have developed resistance not only to established antibiotics but also to standby products. Examples of these include various resistant strains of Staphylococcus aureus and Enterococcus faecium.
To isolate a complex natural product in sufficient quantity and purity for further experiments is usually a difficult and time-consuming, if not impossible, task. Chemists thus follow a different path: They reproduce the natural product in the laboratory from the ground up. This approach is known as total synthesis. To devise such a total synthesis is an enormous scientific challenge. A way must be found to assemble a complicated synthetic molecule faultlessly from simple, available components—and in sufficiently high yield in each reaction step. The total synthesis of platensimycin has now been accomplished by a team headed by the renowned natural products chemist K. C. Nicolaou (The Scripps Research Institute, La Jolla, and University of California, San Diego). Platensimycin consists of an unusual aromatic ring coupled through an amide group to a compact cage structure. The team built these two components—each a veritable challenge for synthetic chemists—separately and then joined them in the final step of the synthesis. "The described chemistry," says Nicolaou, "sets the stage for the synthesis of designed analogues for structure–activity relationship studies in the search for new antibacterial agents."
K.C. Nicolaou, Ph.D. | EurekAlert!
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Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
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