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?
Latrunculin
Actin Polymerization Inhibition in C. elegans
The question asks for a chemical that would be most suitable for directly inhibiting actin polymerization to study its effect on PAR protein localization and cell polarity in C. elegans. Cell polarity in C. elegans zygotes depends on the cortical actin cytoskeleton.
Understanding Actin and Polymerization
Actin is a protein that forms microfilaments, a key component of the cytoskeleton. Actin exists as monomers (G-actin) and can polymerize into filaments (F-actin). This dynamic process of polymerization and depolymerization is crucial for many cellular functions, including cell shape, motility, and the organization of the cell cortex.
Analyzing the Chemical Options
Let's look at the function of each chemical provided in the options:
- Taxol: This drug is a microtubule-stabilizing agent. It binds to tubulin polymers and prevents depolymerization, thus affecting the microtubule cytoskeleton, not the actin cytoskeleton.
- Colchicine: This drug is a microtubule-destabilizing agent. It binds to tubulin dimers and prevents their polymerization, leading to microtubule depolymerization. Like Taxol, it affects microtubules, not actin.
- Latrunculin: Latrunculins (like Latrunculin A or B) are potent inhibitors of actin polymerization. They bind to G-actin monomers and prevent them from being incorporated into growing actin filaments. This effectively reduces the pool of G-actin available for polymerization and leads to the depolymerization of existing F-actin.
- LY294002: This is a PI3-kinase inhibitor. PI3-kinases are enzymes involved in various intracellular signaling pathways, including cell growth, proliferation, differentiation, motility, and survival. While signaling pathways can indirectly affect the cytoskeleton, LY294002 does not directly target actin polymerization.
Selecting the Most Suitable Inhibitor
The investigator specifically wants to directly inhibit actin polymerization. Based on the mechanisms of action described above, Latrunculin is the only chemical among the options that directly interferes with the process of actin polymerization by binding to actin monomers.
Therefore, Latrunculin is the most suitable chemical for inhibiting cortical actin polymerization in C. elegans zygotes to analyze its impact on PAR protein localization and the establishment of cell polarity.
Conclusion
To directly inhibit actin polymerization and study its effects on PAR protein localization and cell polarity in C. elegans, Latrunculin is the appropriate chemical choice.
Important Questions from Cellular communication
In a neuron, proteins and membranes are primarily synthesized in the cell body. These materials must be transported down the axon to the synaptic region using microtubules in an anterograde fashion. Such axonal transport is directed by
Acetylcholine is a potent neurotransmitter, which is released from the neurons. After release they diffuse across the synaptic cleft and combine with nicotinic acetylcholine receptor molecules in the membrane of the postsynaptic cell. The interaction of acetylcholine with the nicotinic acetylcholine receptor produces large transient increase in the permeability of the membrane to specialized ions resulting in signal transduction for nerve impulse. Acetylcholine receptor is a
Column X represents the type of junctions and column Y represents the proteins associated with the junctions.
Column X
Column Y
A.
Anchoring junction
i.
Claudins
B.
Occluding junction
ii.
Delta-Notch
C.
Channel-forming junction
iii.
Desmoglein
D.
Signal-relaying junction
iv.
Connexin
Which one of the following options is a correct match between terms of Columns X and Y?
Bacteria employ various mechanisms to invade or enter host cells, which are either phagocytic or non-phagocytic in nature. Given below are some of the mechanisms which are generally used for carrying out this process.
A. Some bacteria express a protein called invasin that is recognized by host-cell β1 integrins.
B. Actin polymerization along with assembly of clathrin coat results in the internalization of bacteria by zipper mechanism.
C. Some bacteria, including Salmonella enterica, use trigger mechanism to inject a set of effector molecules in the cytosol through type III secretion system.
D. Some bacteria attach to host cell surface receptors inducing local elevation of Ca2+ in cell cytosol, leading to the fusion of lysosomes with bacteria containing plasma membrane vesicles.
Which one of the following represents the combination of correct mechanisms for invading non-phagocytic cells?
Many signal transduction pathways work as molecular switches. On receiving a signal, they switch from an inactive form to an active form. They return to the inactive form when another signal switches them off. Which of the following processes does NOT directly involve a molecular switch?
