Daniela Boassa, Jennifer Lee, Germán Enciso, Christopher Chander, Tracy Lou, Sean Pairawan, Melody Guo, Frederic Wan, Mark Ellisman, Christine Sütterlin, Ming Tan (2017) CIL:50068, 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的最常见原因。它引发了一种不寻常的细胞内感染：在被称为衣原体包涵体的膜结合腔室中，原体（EB）转化为更大、具有代谢活性的网状体（RB）。该RB进行复制，然后转化为EB，即感染形式。我们利用定量三维电子显微镜技术证实，沙眼衣原体RB通过二分裂进行分裂，并且随着种群扩张，其体积缩小六倍。转化仅在至少经过六轮复制后发生，且与RB尺寸的减小相关。这些结果表明，RB仅在达到特定体积阈值以下时转化为EB，这一阈值是通过反复分裂并在体积加倍前达到的。我们的发现支持了一种模型，即RB尺寸通过无需外部信号的机制控制RB向EB转化的时机。