The stomatal complex of Zea mays consists of two guard cells with the pore in between them and two flanking subsidiary cells. Both guard cells and subsidiary cells are important elements for stoma physiology because a wellcoordinated transmembrane shuttle transport of potassium and chloride ions occurs between these cells during stomatal movement. To shed light upon the corresponding transport systems from subsidiary cells, subsidiary cell protoplasts were enzymatically isolated and in turn, analyzed with the patch-clamp technique. Thereby, two K + -selective channel types were identified in the plasma membrane of subsidiary cells. With regard to their voltage-dependent gating behavior, they may act as hyperpolarization-dependent K + uptake and depolarization-activated K + release channels during stomatal movement. Interestingly, the K + channels from subsidiary cells and guard cells similarly responded to membrane voltage as well as to changes in the K + gradient. Further, the inward-and outward-rectifying K + current amplitude decreased upon a rise in the intracellular free Ca 2+ level from 2 nM to the m m m mM-range. The results indicate that the plasma membrane of subsidiary cells and guard cells has to be inversely polarized in order to achieve the anti-parallel direction of K + fluxes between these cell types during stomatal movement.

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Devices and methods for Integrated Bioprocessing have been developed for production of recombinant proteins with the yeast Pichia pastoris. In doing so cross flow filtration techniques for cell separation and product concentration are connected directly to high instrumented cultivation processes. These are equipped with on‐line measuring techniques for substrates and products, e.g., glycerol, methanol and pyruvate as well as recombinant proteins, e.g., the chemokines 1–8del MCP‐1 and vMIP‐II. Complex automation structures allow for process development at virtual plants which can be used as the basis for establishing and implementing fully automated real processes. Experiments for determination of reaction kinetics, optimization of productivity in high‐cell density cultures and Integrated Bioprocessing are outlined, along with detailed illustration of the realization of the methods at industrial pilot plant scale.

Background: MDM4 is a negative regulator of p53 and cooperates with MDM2 in the cellular response to DNA damage. It is unknown, however, whether MDM4 gene alterations play some role in the inherited component of breast cancer susceptibility.

The coding regions of tumour suppressor and cell cycle regulatory genes p21 WAF1 and p27 Kip1 were investigated in 101 feline tumours of various types. No damaging mutations were present in the analysed areas of the genes.