Lab 4 - Gene expression in C elegans

Question 1

What is the egg type and cleavage type of C elegans?

Answer 1

egg type = isolecithal
cleavage type = rotational holoblastic

Question 2

What are the advantages of using C elegans?

Answer 2

• two sexual forms: hemaphrodites can self fertilize –> create a pure lines
• short life cycle
• transparent
• can be frozen
• ease of genetic manipulation
• only 1000 cells
• invariant lineage

Question 3

What is a drawback of C elegans?

Answer 3

can only study basal processes and structures

Question 4

What does unc stand for, and what do mutations cause, what tissue do they affect?

Answer 4

unc = uncoordinated
- altered sinusoidal movements
- either muscle or neural defects

Question 5

What tissue does unc 119 affect and what is the phenotype?

Answer 5

tissue = neural
phenotype = C-shaped movement

Question 6

What tissue does unc 54 affect and what is the phenotype? Is this phenotype always observed?

Answer 6

tissue = muscle
phenotype = can’t move (“rolling pin”)

• temperature affects the phenotype –> denaturing of proteins

Question 7

What is the structure of a transgene?

Answer 7

regulatory region of a gene fused to the coding region of a reporter gene. regulatory region should have known expression pattern

Question 8

What are common reporter genes?

Answer 8

GFP and LacZ

Question 9

How is a transgenic made?

Answer 9

1. insert plasmid with transgene + transposase into F0 embryo
2. cross F0 with WT
3. look at F1 for trasgenics

Question 10

Where are transgenes inserted, does this cause problems?

Answer 10

Randomly inserted into genome –> can disrupt coding regions

Question 11

Whats the difference between a transgene and a transgenic?

Answer 11

transgene = construct
transgenic = organism with the transgene

Question 12

In this lab, what reporter gene was used to observe unc 119 and WT, in what cells is it expressed?

Answer 12

GFP, expressed pan-neuronally

Question 13

How does the unc 119 mutant look compared to WT?

Answer 13

WT = straight neurons
unc 119 = squiggly neurons

Question 14

In this lab, how was muscle visualized in the WT and unc 54 mutants, are there any drawbacks?

Answer 14

• used phalloidin: high affinity for F actin in muscle
• phalloidin was conjugated to GFP
• phalloidin is a statin –> kills organisms

Question 15

How does the unc 54 mutant look compared to WT?

Answer 15

WT = smooth, steel cable
Unc 54 = disorganized and blotchy

Question 16

What is sodium azide?

Answer 16

an anesthetic