CITE seminar series
CITE - Chemicals In the Environment - is a research topic within the Helmholtz programm oriented funding. CITE addresses multiple aspects of the impact of chemicals in the environment. We aim to have a monthly regular seminar series addressing issues related to our activities.
12.11.2013, 1 p.m., KUBUS, Room 2
Dr. Urs Berger
Department of Applied Environmental Science (ITM), Stockholm University, Sweden
State-of-the-art in trace analysis of per- and polyfluoroalkyl substances
Implications for our understanding of their environmental fate
Twelve years ago, the first scientific reports on the presence of perfluorooctane sulfonic acid (PFOS) in blood serum of the general population and on its global distribution in wildlife were published. This triggered an ever-since increasing number of research studies on per- and polyfluoroalkyl substances (PFASs) in humans and the environment. The majority of these studies are based or rely on chemical analysis of PFASs in a variety of matrices. Many of the early-recognized challenges specific to trace analysis of PFASs have eventually been overcome as well-characterized chemical standards became available and analytical methods evolved. Today, a number of highly sensitive methods are described for quantification of many classes of PFASs in a multitude of matrices. The presentation investigates to what extent these existing methods are able to supply the analytical data needed to understand key issues such as environmental sources, transport and fate or human exposure sources and pathways for different PFASs. Potential shortcomings and quality gaps of commonly applied methods, such as procedural blank contamination, matrix effects and varying response factors of structural isomers, are also discussed. A special focus is on particular challenges with emerging groups of PFASs such as perfluoroalkyl phosphonic acids and polyfluoroalkyl phosphate esters.
Urs Berger is the head of a research group at the Department of Applied Environmental Science (ITM), Stockholm University, Sweden. His main interest is the development of trace analytical methods for emerging organic contaminants in different environmental matrices. Furthermore, he applies tailor-made methods in order to gain an understanding for environmental and ecotoxicological pollutant dynamics. Over the last twelve years, an increasing focus has been on per- and polyfluoroalkyl substances (PFASs). Urs Berger has published 42 scientific papers in the field of analysis as well as environmental and ecotoxicological process studies of PFASs.
Host: Thorsten Reemtsma (ANA)
19.11.2013, 12 a.m., KUBUS, Room 1CD
Max Planck Institute for Developmental Biology, Tübingen
Biophysics of morphogen transport
The fundamental question of developmental biology is how a single cell can develop into a complex mature organism with hundreds of different types of specialized cells. Cellular communication via signaling molecules, also known as morphogens, is of central importance to generate this diversity during development. We combine genetic, biophysical and theoretical approaches to study how extracellular morphogens move in developing embryos and how they pattern tissues. We found that morphogens move by hindered diffusion in the extracellular space of living zebrafish embryos: Locally, morphogens can move freely, but their global movement through embryonic tissues is hindered by cell packing (tortuosity) and transient binding to diffusion regulators. Interestingly, differential diffusivity - not stability - of morphogens underlies tissue patterning, consistent with classic reaction-diffusion models that have been postulated to generate complex self-organizing patterns during development.
Host: Till Luckenbach (BIOTOX)