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. A lin-3 loss-of-function mutant with a vulva-less phenotype was mutagenized. Based on your knowledge of the genetic pathway, what types of mutations will suppress the vulva-less phenotype?

Key Concepts

Genetic Pathways

Genetic pathways are networks of genes that interact with each other to regulate biological processes. In the context of C. elegans vulval development, understanding these pathways helps identify how specific genes influence the phenotype. Mutations in certain genes can either enhance or suppress the effects of other mutations, revealing the relationships and functions within the pathway.

Loss-of-Function Mutations

Loss-of-function mutations result in the reduced or abolished activity of a gene product, often leading to a specific phenotype. In the case of the lin-3 mutant, the vulva-less phenotype indicates that the lin-3 gene is crucial for vulval development. Identifying mutations that can suppress this phenotype involves finding other genes that, when mutated, can compensate for the loss of lin-3 function.

Suppressor Mutations

Suppressor mutations are secondary mutations that counteract the effects of a primary mutation, restoring the normal phenotype. In the scenario described, mutations that enhance the activity of genes downstream of lin-3 or that bypass the need for lin-3 function could suppress the vulva-less phenotype. Understanding how these suppressor mutations interact with the original mutation is key to elucidating the genetic pathway.