Chemotaxis
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Chemoattractant receptors in chemotaxis
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Confocal image of GFP-tagged chemoattractant receptors in living amoebae
undergoing chemotaxis. The chemoattractant gradient is established using a
micropipet located just below the frame. Images were captured every 15 seconds.
From Z. Xiao and P.N. Devreotes, Johns Hopkins Medical Institutions. |
G-protein b-subunits in chemotaxis
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Confocal image of GFP-tagged Gb-subunits in living
amoebae undergoing chemotaxis. The chemoattractant gradient is established using a micropipet located just above the frames.
Images were captured every 20 seconds. From T. Jin, N. Zhang, and P.N. Devreotes, Johns Hopkins Medical
Institutions. |
PH-domain translocation with uniform stimulus
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Kinetic analysis of the translocation from the cytoplasm to the plasma
membrane of GFP-tagged CRAC (Cytosolic Regulator of Adenylyl Cyclase-a PH domain
containing protein) in
response to a uniform increase in chemoattractant concentration. Frames were
taken every 2 seconds. The chemoattractant was added just before the cell goes
out of focus. From C.A. Parent and P.N. Devreotes, Johns Hopkins Medical
Institutions.
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PH-domain translocation during chemotaxis
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Confocal image of GFP-tagged CRAC in living amoebae undergoing chemotaxis.
CRAC-GFP specifically translocates to the leading edge of newly elicited
pseudopods. The chemoattractant gradient is established using a micropipet
located near the upper right corner of the frame. Images were captured every 5
seconds. From C.A. Parent and P.N. Devreotes, Johns Hopkins Medical Institutions.
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PH-domain translocation in immobilized cells
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Translocation of CRAC-GFP in cells lacking actin filament formation. Cells
chemotaxing towards the micropipet in the lower portion of the frame were
treated with Latrunculin A and observed within the next few minutes. Images were
captured every 5 seconds. From C.A. Parent and P.N. Devreotes,
Johns Hopkins Medical Institutions.
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PH-domain dynamics in immobilized cells
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Immobilized CRAC-GFP expressing cells can respond to changes in
chemoattractant gradients. Latrunculin A treated cells were subjected to
changing gradients of chemoattractants by moving the micropipet around the cell.
Images were captured every 5 seconds. From C.A. Parent and P.N. Devreotes,
Johns Hopkins Medical Institutions.
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Digitized wild-type cell in chemotaxis
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Three dimensional direct image reconstruction of a D. discoideum
amoebae crawling in a gradient of cAMP. The chemoattractant source is left of the
field. From D. Wessel and D. Soll, Univ. of Iowa |
Digitized clathrin heavy chain null cell in chemotaxis
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Three dimensional direct image reconstruction of a clathrin heavy chain null Dictyostelium
cell. Note the aberrant cell shape, lack of polarity and numerous fragmented
pseudopods. From D. Wessel and D. Soll, Univ. of Iowa.
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