February 17, 1993 TIME: 50 minutes

TOTAL POINTS: 60

(VALUE) QUESTION

(20) 1. Sodium ions play a number of roles in reproduction in echinoderms. Discuss those roles in as much detail as possible. Include in your answer a description of the Na+ fluxes, how such fluxes are controlled, and the consequences of each Na+ flux. Cite experimental evidence to support your statements.

(20 total) 2. When Drosophila females are homozygous for the mutant gene eggnog (egn), cellularization of the blastoderm does not occur in their progeny. However, all progeny of a mating between egn+/egn- males and egn+/egn- females cleave normally. A transgenic Drosophila strain was produced in which the 100 nucleotides upstream of egn+ were fused to the luciferase reporter gene. Luciferase activity determinations gave the following results.

What do these observations tell you about the identities of the cells in which egn is transcribed? (5 points)

What is the term used to describe this kind of mutation? (5 points)

Another transgenic strain was produced in which the 5' untranslated region of the egn+ gene was inserted between the egn+ transcription control region and the luciferase coding region. Luciferase activity determinations gave the following results.

Interpret these results. (10 points)

3. Define or describe

(5) a. inhibin.

(10) b. maturation promotion factor.

(5) c. manchette.