It was the first Monday dissertation in the history of the Elf group. Oscar, the presumptive doctor, did opt for an afternoon defense, and we were all grateful; by 1 p.m., most of us were awake and looking forward to the academic duel. The opponent, Prof. Jaan Männik from the University of Tennessee, Knoxville, chose an offensive approach, carefully scrutinizing every panel of the thesis. With confidence, Oscar delivered his rebuttals carefully, never showing any signs of abashment or frustration. When, after bout two hours, it was time for the committee consisting of Kristina Jonas, Stockholm University, Klas Flärdh, Lund University, and Felipe Cava, Umeå University, they did not dwell on the details because, frankly, there were not many stones left unturned. Instead, they focused on the bigger picture, putting the science in perspective. After the defense, we enjoyed finger food and bubbles in the Öbring room, as tradition dictates. After an unusually short meeting, the committee delivered their verdict; a new doctor was born!

In his thesis, Oscar studies how E. coli bacteria manage to start copying their DNA at just the right time, every time, even when they divide faster than it takes to replicate the whole genome.

A key player in this process is a protein called DnaA, which helps start DNA replication. But only its “active” form can do the job, and it’s regulated by a complex system we don’t fully understand. To investigate, Oscar tagged proteins involved in replication with fluorescent markers and tracked them in real-time as the bacteria grew in tiny microfluidic chambers. The results supported a model where the activation and inactivation of DnaA is the most important regulatory component—but hinted that something else might be involved too.

To this end, Oscar developed a method to find those unknown elements. By randomly disrupting genes across the E. coli genome and spotting which bacteria behaved oddly, he discovered new DNA regions that may help regulate replication. Some were already known—but others were completely new and could potentially unlock deeper insights into how cells control their inner clocks. This approach could be applied to other mysteries in biology too.

Read Oscar’s thesis here