Chapter 18, Problem 20P

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. elegansvulval development.

a. A $\text{lin-3}$ 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?

b. In a complementary experiment, a gain $-$ of $-$ function $\text{let-23}$ mutant with a multi $-$ vulva phenotype was also mutagenized. What types of mutations will suppress the multi $-$ vulva phenotype?