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Pacific Grove (CA)/Leipzig. Researchers have for the first time identified complete gene sequences and function of two proteins in mussels that play a key defensive role against environmental toxicants. These proteins form part of an active, physiological barrier in mussel gills that protects them against environmental toxicants, researchers from the Helmholtz Centre for Environmental Research (UFZ) in Germany and Stanford University in California report in the American Journal of Physiology Regulatory, Integrative and Comparative Physiology. Mussels like the California mussel (Mytilus californianus) can pump over 20 litres of water through their gills every hour. The active barrier protects the organism against harmful substances in the water. The presence of such proteins in mussel gills has been previously indicated, but it is only now that they can be accurately identified. The function of these proteins can be inhibited by chemicals introduced into the environment by humans, e.g. galaxolide, a perfume used in cleaning products. This means that such substances open the way for other chemicals to enter cells. Even chemicals that are not regarded as toxic by conventional standards can enhance toxicity of other compounds. Little is known about the global environmental and human impacts of these 'chemosensitizers'.
Cells have mechanisms that allow them to deal with harmful substances and to survive. One such protective mechanism consists of transport proteins in the cell membrane that act as molecular 'pumps', preventing toxic compounds from accumulating in the cell. This defence mechanism against toxic chemicals is called multi-xenobiotic resistance (MXR). Substances that inhibit the MXR mechanism are called chemosensitizers.
The two recently discovered proteins are both ABC transporters. This cl
|Contact: Tilo Arnhold|
Helmholtz Association of German Research Centres