At high magnification, cells in the S613 isolate have symmetric septa, with only a single septum observed between two cells, and cell separation is easily detected, with single cells visible (Panels A, B, and G). In contrast, multiple septal structures can be seen before complete cell separation in the R712 isolate (Panels A and B, red arrowheads). There are also prominent distortions in the cell envelopes of R712 cells. First, the envelopes appear to be altered at the point of cell contact (which is likely to be the point at which the cells separate) (Panels B, D, and E; blue arrowheads), and the surfaces of the R712 cells lack the smooth appearance of the S613 cells, even when they are in close proximity (a feature observed in all R712 cells analyzed) (Panel E). Second, several structures appear to be connecting the R712 cells (Panels B, C, and F; purple arrowheads); these connecting projections, which were not observed in S613 cells, appear to originate in the cell envelope and maintain the contact between adjacent cells even after the cells have separated. Third, localized protrusions of the cell envelope are a common feature of R712 cells (Panels G and H, black arrowheads). These protrusions were usually observed in proximity to a septal stricture that appeared to originate from the cell envelope. On the other hand, the surface of S613 cells is smooth and symmetric, without any obvious projections or protrusions (more than 100 cells analyzed) (Panels G and H).