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In C. elegans, PAR proteins segregate at the cell cortex in the zygote to establish cell polarity. This is dependent on the regulation of the cortical actin cytoskeleton by RhoA. An investigator sought to directly inhibit actin polymerization to analyze the impact of this inhibition on PAR protein localization. Which one of the following chemicals would be the most suitable?

Correct option is C

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Explanation:

• Latrunculin is the most suitable choice because it directly inhibits actin polymerization by binding to actin monomers (G-actin) and preventing their incorporation into filaments (F-actin).
• Since PAR protein localization in C. elegans depends on cortical actin dynamics, disrupting actin polymerization with Latrunculin helps study its role in cell polarity.

Information Booster:

1. Actin cytoskeleton regulates cell polarity in various organisms, including C. elegans.
2. PAR proteins (Partitioning-defective proteins) establish asymmetric cell division in the embryo.
3. Latrunculin binds to G-actin and prevents F-actin formation, disrupting actin-based processes.
4. Microtubule inhibitors (Taxol, Colchicine) do not target actin and would be ineffective.
5. RhoA signaling regulates actin polymerization, affecting cortical contractility and polarity.

Additional Knowledge :

(1) Taxol (Incorrect - Targets Microtubules)

• Taxol stabilizes microtubules by preventing depolymerization.
• Used in cancer therapy to block cell division.
• Does not affect actin polymerization, so it is not suitable for this experiment.

(2) Colchicine (Incorrect - Targets Microtubules)

• Colchicine inhibits microtubule polymerization by binding to tubulin.
• Used to treat gout and inflammation by disrupting microtubule-dependent processes.
• Does not target actin, making it unsuitable for this study.

(3) Latrunculin (Correct - Inhibits Actin Polymerization)

• Directly binds monomeric G-actin, preventing filament formation.
• Commonly used to study actin-dependent processes, including cell polarity, migration, and division.
• Best choice for inhibiting actin polymerization in this experiment.

(4) LY294002 (Incorrect - PI3K Inhibitor)

• LY294002 is a phosphoinositide 3-kinase (PI3K) inhibitor, affecting signaling pathways.
• Used to study cell growth, survival, and metabolism, not cytoskeletal dynamics.
• Not related to actin polymerization, making it an incorrect choice.