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Chemotaxis and its significance in biology and clinics. Dr. habil. Kőhidai László 2012. Other Cell-physiological effects (e.g. proliferation). Adhesion. Chemotaxis. Phagocytosis. Chemotaxis – Significance in biology. Helps to distinguish / to approach food molecules
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Chemotaxis and its significance in biology and clinics Dr. habil. Kőhidai László 2012.
Other Cell-physiological effects (e.g. proliferation) Adhesion Chemotaxis Phagocytosis
Chemotaxis – Significance in biology • Helps to distinguish / to approach food molecules • Helps to avoid biologically harmful/toxic substances • Sperm to approach oocyte - fertilization • Tissue transformation processes (e.g. CNS) • Immune reaction of multicellular organisms • Proliferation and growing of tumors, formation of metastasis
Chemorepellent materials Chemoattractant materials
Basic concepts – Definitions 1 Chemotaxis: Migratory response of self-directed, motile cells. Direction and speed of migration is influenced by the concentration of molecules solved in the environment. VECTORIAL movement
Basic concepts – Definitions 2 Chemokinesis: Characteristic parameters (speed, frequency, amplitude) of motile cells are randomely changing due to the influence of environmental factors. NON vectorial !
Chemotaxis – Induced by dissolved molecules Concentration of meolacules inducing migration
Effect of molecules bound to the surface Haptotaxis Concentration gradient of molecules bound onto the surface
Necrotaxis LASER Migration of cells is modulated (induced or blocked) by the biologically active substances released from the dead cells.
Conditions of migration • Ligands/substances inducing the migration • Motile cells • Receptors capable to detect ligands • Effector mechanisms – e.g. cytoskeletal system
Main steps accompanying receptor dependent migration of eukaryotes • Deformation of the cell • Cell adhesion • Cilliary/ flagellar movement
Main groups of chemoattractant ligands • ions of inorganic salts (K+, Cl-) • amino acids (methionine, serine) • biogenic amines • oligopeptides (bacterial tripeptides) • hormones (insulin) • chemokines (interleukin 8) • feromones • synthetic substances (drugs)
bacteria amebas ciliated eukaryotes „Classical” target cells
Target cells in higher ranked organisms neutrophil granulocyte endothel monocyte eosinophil granulocyte lymphocyte
Ligand • Hormone • Immune • Nerve system • Drug Location • Surface membrane • Cytoplasme • Nucleus Receptor classes
Main characteristics of receptors • Specificity – structure • Affinity – effect at low conc. • Saturabiliy – number of receptors • Reversibility • Specific response of the cell