Drosophila

Question 1

What percentage of known human disease genes have a a match in the fruit fly?

Answer 1

75%

Question 2

What are balancer chromosomes?

Answer 2

Multiple inversions in one chromosome (the balancer) prevents recombination with its homologous chromosome. This is useful for maintaining stocks and tracking recessive phenotypes in the progeny.

Question 3

What is the UAS/GAL4 expression system?

Answer 3

Crossing of two fly lines: One has tissue specific expression of GAL4 under an inducible promoter. The other has UAS (upstream activating sequence) which is upstream of a transgene e.g GFP. Progeny flies will have tissue specific expression of GAL4 which then binds to the UAS giving tissue specific expression of the transgene. If it was GFP - tissue specific green fluorescence

Question 4

What is cell competition in drosophila?

Answer 4

Within a growing tissue, two cell populations with different growth rates confront eachother. This results in the growth of the stronger population at the expense of the weaker one.

Question 5

What is the principal method of extending lifespan in c.elegans drosophila and mice.

Answer 5

Down-regulation of major nutrient sensing pathways:

1) Insulin/insulin-like growth signalling
2) Target of rapamycin signalling (mTOR)

Question 6

What does the TOR pathway integrate signals from?

Answer 6

Amino acid supply
Cellular energy state
growth factors
Stresses
Result is to adjust metabolism and growth accordingly from signals.

Question 7

What is the effect of rapamycin

Answer 7

Inhibition of TORC1 - this inhibits activation of S6K which activates autophagy.

Question 8

What is the result when S6K is actively expressed in drosophila which are being treated with rapamycin?

Answer 8

Rapamycin can no longer extend their lifespan.

Question 9

What is the effect of ablating some of the drosophilas insulin signalling capability?

Answer 9

Extends the lifespan of the fly

Question 10

Is rapamycin selective for TORC1 or TORC2?

Answer 10

TORC1

Question 11

What is autophagy?

Answer 11

In stressed cells (starved/growth factor deprivation). The decreased intracellular nutrients leads to autophagy. An intracellular membrane captures a portion of the cytoplasm forming the autophagosome which then fuses with the lysosome. The autolysosome degrades cytoplasmic material which can supply amino acids or fatty acids that can be used for protein synthesis or ATP production. Ultimately leads to cellular survival.