Daniela Boassa, Jennifer Lee, Germán Enciso, Christopher Chander, Tracy Lou, Sean Pairawan, Melody Guo, Frederic Wan, Mark Ellisman, Christine Sütterlin, Ming Tan (2017) CIL:50051, 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最常见的病原体。其引起一种独特的细胞内感染：在称为衣原体包涵体的膜结合隔室中，原体（EB）转化为较大的、代谢活跃的网状体（RB）。此RB通过二分裂进行复制，然后转化为EB，即感染形式。我们采用定量三维电子显微镜技术，证实了沙眼衣原体RB通过二分裂进行分裂，并在种群扩张过程中体积缩小六倍。转化仅在至少六轮复制之后发生，并与较小的RB体积相关。这些结果表明，RB仅在达到特定体积阈值以下时转化为EB，该阈值通过反复分裂并在体积加倍之前达到。我们的发现支持了一种模型，在该模型中，RB体积控制了RB向EB转化的时机，而无需外部信号的介入。