Question

1.) How can we tell if the inlA and inlB genes are expressed constructively or are induced in the presence of the human receptors?

2.) Might these genes be normally expressed at low levels, but undergo increased transcription once in contact with intestinal epithelial cells? how could this be determined?

Answer 1

Please find the answers below:

Answer 1: Constructively expressed genes are those which are expressed in a cell under all conditions, whether normal or stress/stimulus is present. On the other hand, an induced gene is the one which expresses itself only under a specific condition of stress/stimulus. Thus, a positively and negatively backed-up controlled experiment can be conducted in cultured cells which contain this gene and the two set of cells can be subjected to stress/stimulus. The protein can be extracted and subjected to western blot against the appropriate antibody. Any change in expression level in two sets will demonstrate induced expression whereas similar band intensity in all experimental group will show constructive expression.

Answer 2: In order to investigate the effect of intestinal epithelial cells on expression level of the gene, a co-culture of host-cell with epithelial cells can be conducted and a control set of culture can be maintained having only the host cell line. Extraction of protein and post-extraction analysis by western blotting can be used to investigate any change in band intensity for the two samples. Any deviation in the band intensity would demonstrate the positive regulation of host gene in presence of intestinal epithelial cells.