Deletion of the α-synuclein gene locus in the BL6JHUK strain. A. Semi-quantitative analysis of α-synuclein expression in BL6JHUK mice by RT-PCR, sized on a 1.5% agarose gel. A 568 bp α-synuclein band is detected after as few as 20 PCR cycles on brain total RNA of an ICR mouse at P15. No signal was detected in the BL6JHUK sample even after 35 cycles. However, when the BL6JHUK sample was contaminated with as little as 0.01% ICR RNA, the α-synuclein band could still be detected after 35 PCR cycles. The control shows amplification of a 473 bp tubulin fragment with constant 35 cycles. B. Probing for the presence of the α-synuclein gene in the ICR, 129/Ola, BL6JHUK, BL6N, BL6, and BL6Jax strains. Genomic α-synuclein DNA fragments of exon 4 and of exon 6 were amplified by PCR and the products separated on a 2% agarose gel. In a control experiment, a fragment of the NR1 gene was amplified. Fragment sizes are 130 bp, 266 bp, and 508 bp, respectively. C. Genomic PCR on BL6JHUK and BL6Jax DNA with the markers Atoh2, D6Mit122, D6Mit357, Atoh1, and D6Mit299. The D6Mit357 signal was absent from the BL6JHUK strain, whereas all other markers amplified on the two DNA samples. Atoh2 and D6Mit122 are both currently mapped to about 1 cM upstream of Snca (marker D6Mit357), Atoh1 and D6Mit299 both to about 1 cM downstream of this locus [; and databases cited there]. PCR products were separated on a 2% agarose gel.