While the experimental work was initially intended to be performed in an organism called Creolimax fragrantissima, it soon became clear that due to technical challenges and irreproducibility of results, carrying out the project as was initially planned would not be possible. Instead, I switched focus to another ichthyosporean species called Sphaeroforma arctica. I serendipitously discovered that its unique cell division cycle can easily be synchronized, which allowed elegant experimental manipulation. Using my previous expertise in quantitative cell biology, I analyzed the relationship between the cell size and cell division using quantitative experiments and mathematical modeling. I found that in S. arctica, division of nuclei is under control of a timer, which is unique among unicellular organisms, and represents a significant discovery in the field of cell division cycle. The manuscript describing this work has been published in a prestigious journal Current Biology.
To begin to study the genome regulation in ichthyosporeans, I then analyzed gene expression throughout the entire cell cycle, making use of the protocols for synchronization. We found that there is a highly coordinated transacriptional regulation in the last stage of the cycle, where Sphaeroforma arctica cells undergo a coordinated transition into a transiently multicellular state. Furthermore, combining with a bioinformatics analysis, we found that this transiently multinucleated state involves upregulation of homologs of animal cell adhesion molecules. This discovery pointed out that multicellularity in animals and ichtyosporeans might have a common cell adhesion mechanism. The results of this study, which involved several collaborators and also included a comprehensive cell biological analysis of this transiently multicellular state using advanced microscopy, as well as re-sequencing of the entire genome of Sphaeroforma arctica, will soon be published.
Finally, to get insight into genome regulatory mechanisms, which was the initial main aim of PREMETAZOAEPIGENOME, we have, with Alfonso Mendaña Gomez, a MSc student in the lab, established and optimized protocols for the genomic assays, in both Sphaeroforma arctica and Creolimax fragrantissima. Establishment of these protocols is the first step towards the investigation of genome regulatory mechanisms.
