The Last Universal Common Ancestor of Ribosome-Encoding Organisms: Portrait of LUCA.

The existence of LUCA in the distant past is the logical consequence of the binary mechanism of cell division. The biosphere in which LUCA and contemporaries were living was the product of a long cellular evolution from the origin of life to the second age of the RNA world. A parsimonious scenario suggests that the molecular fabric of LUCA was much simpler than those of modern organisms, explaining why the evolutionary tempo was faster at the time of LUCA than it was during the diversification of the three domains.

From Mimivirus to Mirusvirus: The Quest for Hidden Giants.

Our perception of viruses has been drastically evolving since the inception of the field of virology over a century ago. In particular, the discovery of giant viruses from the phylum marked a pivotal moment. Their previously concealed diversity and abundance unearthed an unprecedented complexity in the virus world, a complexity that called for new definitions and concepts.

Dry mass photometry of single bacteria using quantitative wavefront microscopy.

Quantitative phase microscopy (QPM) represents a noninvasive alternative to fluorescence microscopy for cell observation with high contrast and for the quantitative measurement of dry mass (DM) and growth rate at the single-cell level. While DM measurements using QPM have been widely conducted on mammalian cells, bacteria have been less investigated, presumably due to the high resolution and high sensitivity required by their smaller size. This article demonstrates the use of cross-grating wavefront microscopy, a high-resolution and high-sensitivity QPM, for accurate DM measurement and monitoring of single microorganisms (bacteria and archaea).

Mirusviruses link herpesviruses to giant viruses.

DNA viruses have a major influence on the ecology and evolution of cellular organisms, but their overall diversity and evolutionary trajectories remain elusive. Here we carried out a phylogeny-guided genome-resolved metagenomic survey of the sunlit oceans and discovered plankton-infecting relatives of herpesviruses that form a putative new phylum dubbed Mirusviricota. The virion morphogenesis module of this large monophyletic clade is typical of viruses from the realm Duplodnaviria, with multiple components strongly indicating a common ancestry with animal-infecting Herpesvirales.