A powerful approach to identifying genes of a developmental pathway is to screen for mutations that suppress or enhance the phenotype of interest. This approach was undertaken to elucidate the genetic pathway controlling C. elegans vulval development. In a complementary experiment, a gain-of-function let-23 mutant with a multi-vulva phenotype was also mutagenized. What types of mutations will suppress the multi-vulva phenotype?

Verified step by step guidance

1. Identify the role of the let-23 gene in C. elegans vulval development. The let-23 gene is part of the epidermal growth factor receptor (EGFR) pathway, which is crucial for proper vulval development.
2. Understand the nature of a gain-of-function mutation. A gain-of-function mutation in let-23 leads to excessive signaling, resulting in a multi-vulva phenotype.
3. Consider the genetic interactions that could suppress the multi-vulva phenotype. Suppressor mutations could occur in genes that are downstream or parallel to let-23 in the signaling pathway.
4. Focus on mutations that reduce or inhibit the overactive signaling caused by the gain-of-function let-23 mutation. These could include loss-of-function mutations in downstream effectors or negative regulators of the pathway.
5. Explore potential candidates for suppressor mutations, such as genes encoding proteins that negatively regulate the EGFR pathway, like phosphatases or other inhibitory molecules.

Key Concepts

Gain-of-Function Mutations

Gain-of-function mutations result in a gene product with enhanced or new functions. In the context of the let-23 gene in C. elegans, such mutations can lead to a multi-vulva phenotype by overactivating signaling pathways involved in vulval development. Understanding these mutations is crucial for identifying how they can be suppressed by other genetic changes.

Suppressor Mutations

Suppressor mutations are genetic alterations that counteract the effects of a primary mutation, restoring the normal phenotype. In the case of the let-23 gain-of-function mutation, suppressor mutations may occur in downstream components of the signaling pathway or in genes that negatively regulate vulval development, thereby reducing the multi-vulva phenotype.

Genetic Pathways

Genetic pathways are networks of genes that interact to control specific biological processes. In C. elegans vulval development, various genes work together to regulate cell fate decisions. Understanding these pathways is essential for predicting how mutations can influence phenotypes and for identifying potential suppressors of gain-of-function mutations.