Female Drosophila that are homozygous for a mutant form of the bicoid maternal effect gene produce eggs that,when fertilized,develop into larvae with no head or thorax.Which procedure would most likely lead to restoration of normal development in one of these mutant eggs?
A) Adding cytoplasm from the anterior end of a normal egg to the anterior end of the mutant egg
B) Adding cytoplasm from the posterior end of a normal egg to the posterior end of the mutant egg
C) Disrupting expression of the mutant bicoid gene in the egg
D) Forcing expression of the nanos gene in the egg
E) Knocking out expression of the nanos gene in the egg

Question

Quizplus · Accepted Answer

Bicoid mRNA is synthesized at the anterior end of the oocyte and concentrates there. Therefore, by adding cytoplasm from the anterior end of a normal egg to the anterior end of the mutant egg, the mutant cytoplasm would be supplemented with normal bicoid mRNA, leading to restoration of normal development. Adding cytoplasm from the posterior end of a normal egg (choice B) would not provide the necessary bicoid mRNA. Disrupting expression of the mutant bicoid gene in the egg (choice C) would not be possible without genetic manipulation of the organism. Forcing expression of the nanos gene in the egg (choice D) would not address the issue of the missing bicoid mRNA. Knocking out expression of the nanos gene in the egg (choice E) would not address the issue of the missing bicoid mRNA either.

Female Drosophila That Are Homozygous for a Mutant Form of the Bicoid