Date of Award


Degree Type


Degree Name

Master of Science




Dr. David Haniford

Second Advisor

Dr. Greg Gloor

Third Advisor

Dr. David Edgell


Plasmids containing the pB10 integron were used to examine if there are regulatory mechanisms that can up-regulate the expression of integron genes independent of transposition to the front of the array. Selection assays of cultures harbouring the integron containing plasmids on ampicillin concentrations greater than the minimal inhibitory concentration resulted in plasmid deletion events and an increased resistance to ampicillin. Integron gene transcripts from the deletion plasmids originated from the tetracycline or chloramphenicol resistance gene promoters increasing levels of all transcripts as determined by RT-PCR. This increased transcription resulted in increased translation of not only oxa2, but qacEΔl located beyond the first gene cassette. Ribonuclease protection assays showed that the oxa2 attC site is not involved in transcriptional termination. However there is a Rho- independent transcriptional terminator present in the orfE-like gene cassette that provides 20-30% termination. Together, these data indicate that events increasing transcription of the first gene cassette also increase expression of downstream genes, and gene cassettes can have imbedded elements that affect expression of downstream genes.



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