Markel has worked in the field of botulinum neurotoxins (BoNTs) during his PhD in Pål Stenmark's team, using X-ray crystallography and cryo-EM to solve the structure of several proteins related to the botulinum neurotoxins. His main cryo-EM project consisted in structural work on the 300 kDa complex of the novel BoNT serotype X and its partner protein NTNH. He has been trained as an internal user of the cryo-EM microscopes at the SciLifeLab Stockholm node and has several years of experience in sample preparation, sample screening and data processing as well as workstation hardware support.