Question

A graduate student decided to investigate the effects of heat on the expression of the VirD gene of Agrobacterium tumefaciens cells. He grew two batches of cells, one at 28 oC and the other at 32 oC. He then measured the transcriptional expression of the VirD gene by qPCR in both cells, and collected the following data.

Average CT (VirD); n = 3

Grown at 28 oC

25

Grown at 32 oC

20

a) What does this data imply about the relative expression of the VirD gene grown at different temperatures? (3 points)

b) Is the experiment reliable (3 point)? Explain? (4 points)

Answer 1

Ans (a) The realtive expression of VirD gene is higher at 32 degree temperature grown Agrobacterium. Because, the lower the Ct value means the higher expression of gene compared to the sample havig higher ct value. Thus, Ct value of VirD gene is 25 at 28 degree grown cells whereas Ct value is 20 at 32 degree grown cells. Thus, at 32 degree have higher expression of VirD gene.

Ans (b) No, the experiment is not reliable because the chances of error in real time PCR are very higher. For, getting the reliable data we should use the house keeping control gene like actin along with VirD. Now, the level of expression of housekeeping genes for each case will be similar. Then we can easily compare the expression of our VirD gene and normalised with housekeeping gene

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