Figure 1. Immunolocalization by transmission electron microscopy of GroEL in ultrathin sections of A. actinomycetemcomitans ATCC 29522. Unstressed cells (Panel A) and heat-stressed cells (30 min at 43°C) (Panel B) were labeled with use of a specific antibody raised against the purified A. actinomycetemcomitans ATCC 29522 GroEL. More gold particles are observed both inside and outside stressed bacteria compared with unstressed bacteria.