In bacteria, the earliest stage of cell division is the formation of the Z ring at the division site at the cell centre. It has been shown in Bacillus subtilis that Z ring assembly is coupled with the early stages of DNA replication1, 2. The chromosome (nucleoid) also influences the position of the division site via the actions of Noc (nucleoid occlusion) which binds the chromosome and prevents Z ring assembly over it too early in the replication round3. Both systems ensure each daughter cell receives a complete genetic complement. When DNA replication is blocked at the earliest stage of DNA replication (initiation), midcell Z rings are unable to form and this is partly due to the activity of Noc4. However, another DNA-binding protein, Spo0J, has been shown to influence Z ring placement5. Therefore, we hypothesised that Spo0J may have a nucleoid occlusion function. To test this, mutant strains lacking spo0J were constructed. Initiation of DNA replication was inhibited during the first round of replication using the spore outgrowth system and Z rings were observed in live cells using an ftsZ-yfp fusion and fluorescence microscopy. A significant increase in the frequency of midcell Z rings was observed in cells lacking Spo0J when initiation was blocked, to a similar frequency previously observed in cells lacking Noc. These results support our hypothesis of Spo0J having a nucleoid occlusion function. We are now testing whether removing both Noc and Spo0J would result in complete midcell Z ring assembly when initiation of DNA replication is blocked. If so, this would connect the nucleoid occlusion proteins with the coupling of DNA replication and division site placement.