Chemotaxis and its significance in biology and

clinics

Dr. habil. Kőhidai László

2012.

ChemotaxisChemotaxis PhagocytosisPhagocytosisAdhesionAdhesion

Other Other Cell-physiological Cell-physiological effects effects (e.g. proliferation)(e.g. proliferation)

Chemotaxis – Significance in biologyChemotaxis – Significance in biology

Helps to distinguish / to approach food moleculesHelps to distinguish / to approach food molecules

Helps to avoid biologically harmful/toxic substances Helps to avoid biologically harmful/toxic substances

Sperm to approach oocyte - fertilization Sperm to approach oocyte - fertilization

Tissue transformation processes (e.g. CNS) Tissue transformation processes (e.g. CNS)

Immune reaction of multicellular organismsImmune reaction of multicellular organisms

Proliferation and growing of tumors, formation Proliferation and growing of tumors, formation

of metastasisof metastasis

Migration

Kinesis Taxis

Chmokinesis(direction)

Ortokinesis(speed)

Klinokinesis(frequency)

Chemotaxis Haptotaxis Necrotaxis

Chemoattractant materials

Chemorepellent materials

Basic concepts – Definitions 1Basic 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 theenvironment.

VECTORIAL movement

ChemotaxisChemotaxis

Chemokinesis:

Characteristic parameters (speed, frequency, amplitude) of motile cells are randomely changing due to the influence of environmental factors.

NON vectorial !

Basic concepts – Definitions 2Basic concepts – Definitions 2

ChemokinesisChemokinesis

Concentration of meolacules inducing migration

Chemotaxis – Induced by dissolved moleculesChemotaxis – Induced by dissolved molecules

Concentration gradient of moleculesbound onto the surface

Effect of molecules bound to the surfaceEffect of molecules bound to the surface

HaptotaxisHaptotaxis

NecrotaxisNecrotaxis

LASER

Migration of cells is modulated (induced or blocked) by the biologicallyactive substances released from the dead cells.

Nekrotaxis

Conditions of migrationConditions of migration

Ligands/substances inducing the migration

Motile cells

Receptors capable to detect ligandsReceptors capable to detect ligands

Effector mechanisms – e.g. cytoskeletal systemEffector mechanisms – e.g. cytoskeletal system

Main steps accompanying receptor Main steps accompanying receptor dependent migration of eukaryotesdependent migration of eukaryotes

Deformation of the cellDeformation of the cell

Cell adhesionCell adhesion

Cilliary/ flagellar movementCilliary/ flagellar movement

Chemotactic substancesChemotactic substances

Main groups of chemoattractant ligandsMain groups of chemoattractant ligands

ions of inorganic saltsions of inorganic salts (K+, Cl-)

amino acids (methionine, serine)

biogenic amines

oligopeptidesoligopeptides (bacterial tripeptidesbacterial tripeptides)

hormones (insulin)

chchemokines (interleukin 8interleukin 8)

feromones

synthetic substances (drugs)

Target cellsTarget cells

„„Classical” target cellsClassical” target cells

bacteria

ciliated eukaryotes

amebas

Target cells in higher ranked organismsTarget cells in higher ranked organisms

neutrophil granulocyte endothel

monocyte eosinophil granulocytelymphocyte

ReceptorsReceptors

Receptor classesReceptor classes

HormoneHormone

ImmuneImmune

Nerve systemNerve system

DrugDrug

LigandLocation

Surface membraneSurface membrane

CytoplasmeCytoplasme

NucleusNucleus

Main characteristics of receptorsMain characteristics of receptors

Specificity – structureSpecificity – structure

Affinity – effect at low conc.Affinity – effect at low conc.

Saturabiliy – number of receptorsSaturabiliy – number of receptors

ReversibilityReversibility

Specific response of the cellSpecific response of the cell