Tanja Hartmann

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35S-sulphate was flap-fed to poplar leaves of different leaf development stages - young developing, expanding, mature, and old mature poplar leaves. (35)S-sulphate was taken up independent of the leaf development stage. Whereas young development leaves did not export the (35)S taken up, export increased with increasing leaf development stage. Expanding(More)
The chemokine CXCL12 promotes migration of human leukocytes, hematopoietic progenitors, and tumor cells. The binding of CXCL12 to its receptor CXCR4 triggers Gi protein signals for motility and integrin activation in many cell types. CXCR7 is a second, recently identified receptor for CXCL12, but its role as an intrinsic G-protein-coupled receptor (GPCR)(More)
Lymphocyte motility in lymph nodes is regulated by chemokines, but the contribution of integrins to this motility remains obscure. Here we examined lymphocyte migration over CCR7-binding chemokines that 'decorate' lymph node stroma. In a shear-free environment, surface-bound lymph node chemokines but not their soluble counterparts promoted robust and(More)
The human chemokine receptor CRAM (chemokine receptor on activated macrophages), encoded by the gene CCRL2, is a new candidate for the atypical chemokine receptor family that includes the receptors DARC, D6 and chemocentryx chemokine receptor (CCX-CKR). CRAM is maturation-stage-dependently expressed on human B lymphocytes and its surface expression is(More)
Glutathione (GSH) is the major low molecular weight thiol in plants with different functions in stress defence and the transport and storage of sulphur. Its synthesis is dependent on the supply of its constituent amino acids cysteine, glutamate, and glycine. GSH is a feedback inhibitor of the sulphate assimilation pathway, the primary source of cysteine(More)
Small cell lung cancer (SCLC) is an aggressive, rapidly metastazising neoplasm with a high propensity for marrow involvement. SCLC cells express high levels of functional CXCR4 receptors for the chemokine stromal-cell-derived factor-1 (SDF-1/CXCL12). Adhesion of SCLC cells to extracellular matrix or accessory cells within the tumor microenvironment confers(More)
Growth and survival of chronic lymphocytic leukemia (CLL) B cells are favored by interactions between CLL and nontumoral accessory cells. CLL cells express CXCR4 chemokine receptors that direct leukemia cell chemotaxis. Marrow stromal cells or nurselike cells constitutively secrete CXCL12, the ligand for CXCR4, thereby attracting and rescuing CLL B cells(More)
Homing to secondary lymphoid organs and bone marrow (BM) is a central aspect of leukemic pathophysiology. We investigated the roles of the two major lymphocyte integrins LFA-1 and VLA-4 on B-cell chronic lymphocytic leukemia (CLL) cells in these processes. We found that the majority of CLL cells expressed significantly reduced LFA-1 due to low beta2(More)
Algorithms or target functions for graph clustering rarely admit quality guarantees or optimal results in general. Based on properties of minimum-cut trees, a clustering algorithm by Flake et al. does however yield such a provable guarantee, which ensures the quality of bottlenecks within the clustering. We show that the structure of minimum s-t-cuts in a(More)