We've seen lots of geeky proposals in which a guy or gal will draw on on a shared love of fandom when asking to marry their significant other. This particular fellow and his lady friend both happen to be biologists, so he decided to let his polymerase chain reaction products do the talking, giving his girlfriend a big surprise when she imaged his electrophoresis gel.
After seeing his proposal pop up on reddit, the proposer (identified by the user name gdiguy2) explained how he pulled off his PCR propsal:
They're 5 sized PCR fragments (roughly 150, 300, 500, 700, 1kb), I went back through my notes to find 5 primer pairs that I knew worked pretty well (so don't feel bad, they're selected out of primers that had been pre-validated =p). The other lanes are just mixes of the 5 sizes (either 2:3:4 or 4:6 volume mixes going in decreasing size, since larger fragments tend to be brighter). The gel actually didn't take that long (though it was terrifying loading it), but I made a mockup in Illustrator beforehand (along with a ladder to test what sizes to use), and then sketched it out beforehand so I knew what to add to each lane.
He also explains that the actual verbal proposal came outside the lab a few minutes later, and involved flowers instead of gel. The PCR proposal was a bit of work, but was less messy than the proposal friends suggested for his mouse geneticist girlfriend: hiding her ring inside a dead mouse and having her dissect it.