Daniela Boassa, Jennifer Lee, Germán Enciso, Christopher Chander, Tracy Lou, Sean Pairawan, Melody Guo, Frederic Wan, Mark Ellisman, Christine Sütterlin, Ming Tan (2017) CIL:50060, Chlamydia trachomatis, Human HeLa. CIL. Dataset

Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infection. It produces an unusual intracellular infection: within a membrane-bound compartment called the chlamydial inclusion, the elementary body (EB) converts into the larger, metabolically-active reticulate body (RB). This RB replicates and then converts into an EB, which is the infectious form. We used quantitative three-dimensional electron microscopy to show that C. trachomatis RBs divide by binary fission and undergo a six-fold reduction in size as the population expands. Conversion only occurs after at least six rounds of replication, and correlates with smaller RB size. These results suggest that RBs only convert into EBs below a size threshold, reached by repeatedly dividing before doubling in size. Our findings support a model in which RB size controls the timing of RB-to-EB conversion without the need for an external signal.

沙眼衣原体是细菌性性传播感染中最常见的病原体。其感染方式异常，即在被称为衣原体包涵体的膜包裹的细胞内腔室中，原体（EB）转变为较大的、代谢活跃的网状体（RB）。该RB进行复制后，再转变为EB，而EB即为感染形态。本研究采用定量三维电子显微镜技术，展示了沙眼衣原体RB通过二分裂进行分裂，并在种群扩张过程中尺寸缩小六倍。转变仅在至少六轮复制之后发生，且与较小的RB尺寸相关。这些结果表明，RB仅在达到一个尺寸阈值以下时才转变为EB，这一阈值是通过反复分裂并在尺寸加倍前达到的。我们的发现支持一种模型，即RB尺寸控制RB向EB转变的时间，而不需要外部信号的介入。