The group is predominantly interested in the fine- and ultrastructural localization of molecular components of the neuronal signal transduction machinery, especially receptors, ion channels, and functionally related proteins in identified neuronal systems of the mammalian brain. Functionally important molecules such as alpha and beta subunits of potassium channels are localized at the mRNA level by in-situ-hybridisation and the protein level by immunocytochemistry by light and electron microscopy.
For these purposes, selected amino acid sequences are produced as recombinant proteins to raise, characterize and purify antibodies. Channel proteins are visualized by preembedding techniques with different enzymatic (peroxidase and alkaline phosphatase) and particulate (immunogold, iron oxide-dextran) markers at the cellular and subcellular level. Selected proteins are localized to identified neurons or synapses by fluorescent or immunoenzymatic double labeling techniques. Energy filtered transmission electron microscopy (EFTEM) is used to detect specific markers (cerium ions, iron oxide dextran) linked to antibodies or in the enzymatic reaction products for double labeling at the electron microscopic level. With post-embedding immunogold labeling, we are able to localize the targets quantitatively with a resolution of 20 nm (maximum gold particle distance). For post-embedding, techniques like freeze substitution or low temperature embedding in acrylic or epoxy resins are supplemented by ultrathin cryosection procedures according to Tokuyasu.
With our approach we intend to improve the molecular understanding of information processing in selected neuronal circuits.