Daniela Boassa, Jennifer Lee, Germán Enciso, Christopher Chander, Tracy Lou, Sean Pairawan, Melody Guo, Frederic Wan, Mark Ellisman, Christine Sütterlin, Ming Tan (2017) CIL:50062, 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。它引发一种异常的细胞内感染：在被称为衣原体包涵体的膜结合室中，原体（EB）转化为较大的、代谢活跃的网状体（RB）。此RB进行复制后转化为EB，即感染形式。我们运用定量三维电子显微镜技术展示了沙眼衣原体RB通过二分裂方式繁殖，并在种群扩大过程中其体积缩小至原来的六分之一。这种转化仅在至少六轮复制之后发生，且与RB体积的减小相关。这些发现表明，RB仅在体积低于某一阈值时转化为EB，这一阈值通过反复分裂并在体积加倍前达到。我们的研究结果支持一种模型，即RB体积通过无需外部信号的机制控制RB至EB转化的时机。