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If you treat a moving neutrophil with cytochalasin (preventing actin polymerization) it loses its ability to follow a bacterium.

A) Why is this?
B) What is a signaling pathway that might lead from detection of a bacterial protein to changes in the cytoskeleton?
C) Are the cytoskeletal changes localized or do they take place in the entire cell? Why might this be important?

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A) Cytochalasin prevents actin polymerization, disrupting the neutrophil's ability to undergo chemotaxis and follow a bacterium.

B) The Rho GTPase signaling pathway can lead from detection of a bacterial protein to cytoskeletal changes.

C) Cytoskeletal changes are localized, facilitating targeted cell movement towards the bacterial threat, crucial for efficient immune response.

A) Cytochalasin is a compound that inhibits actin polymerization, a critical process for the formation of the cell's cytoskeleton. Neutrophils, a type of white blood cell, rely on dynamic changes in their cytoskeleton to undergo chemotaxis, which enables them to move toward a target, such as a bacterium. By preventing actin polymerization, cytochalasin disrupts the cytoskeletal dynamics essential for the neutrophil's ability to follow and engulf a bacterium.

B) The Rho GTPase signaling pathway is a key mechanism that transduces signals from the detection of bacterial proteins to changes in the cytoskeleton. When a neutrophil detects a bacterial threat, signaling pathways, including Rho GTPases, are activated. Rho GTPases regulate the reorganization of the actin cytoskeleton, leading to the formation of membrane protrusions and cell movement.

C) Cytoskeletal changes in response to bacterial detection are localized, primarily occurring in the region of the cell facing the bacterial stimulus. This localized response is crucial for directed cell movement, allowing the neutrophil to efficiently navigate towards the site of infection. Localized cytoskeletal changes enable the formation of pseudopodia, extensions of the cell membrane, which guide the neutrophil's movement and facilitate effective immune responses against the bacterial threat.

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