Mitochondria and chloroplasts are now called organelles, but they used to be bacteria. As they transitioned from endosymbionts to organelles, they became more and more integrated into the biochemistry and cell biology of their hosts. Work over the last 15 years has shown that other symbioses show striking similarities to mitochondria and chloroplasts. In particular, many sap-feeding insects house intracellular bacteria that have genomes that overlap mitochondria and chloroplasts in terms of size and coding capacity. The massive levels of gene loss in some of these bacteria suggest that they, too, are becoming highly integrated with their host cells. Understanding these bacteria will require inspiration from eukaryotic cell biology, because a traditional microbiological framework is insufficient for understanding how they work.

中文翻译：

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从微生物学到细胞生物学：当细胞内细菌成为其宿主细胞的一部分时。

线粒体和叶绿体现在称为细胞器，但它们曾经是细菌。当它们从共生菌过渡到细胞器时，它们越来越融入宿主的生物化学和细胞生物学中。过去15年的工作表明，其他共生体与线粒体和叶绿体具有惊人的相似性。特别是，许多以汁液为食的昆虫饲养的细胞内细菌的基因组在大小和编码能力方面都与线粒体和叶绿体重叠。这些细菌中某些细菌的大量基因损失表明，它们也正与宿主细胞高度整合。了解这些细菌将需要真核细胞生物学的启发，因为传统的微生物学框架不足以了解它们的工作原理。