doxycycline long term side effects The PCR were carried out using the following primers d2EYFP forward 5 acgacggcactcaagacc- 3; d2EYFP reverse 5 gtcctccttgaagtcgatgc- 3; PFL tTA forward 5 aaagcagctgaagtgcgagag- 3; PFL tTA reverse 5 gatggtgctgccgtagttgtt- 3; NO PFL tTA forward 5 acagcgcattagagctgctt- 3; NO PFL tTA reverse 5 acctagcttctgggcgagtt- 3.