SUMMARY Fifty years ago, David Baltimore published a brief conceptual paper delineating
the classification of viruses by the routes of genome expression. The six “Baltimore classes” …

Viruses have been infecting their host cells since the dawn of life, and this extremely long-
term coevolution gave rise to some surprising consequences for the entire tree of life. It is …

Microbial and viral communities transform the chemistry of Earth's ecosystems, yet the
specific reactions catalyzed by these biological engines are hard to decode due to the …

Conventional CRISPR–Cas systems maintain genomic integrity by leveraging guide RNAs
for the nuclease-dependent degradation of mobile genetic elements, including plasmids and …

Halophilic archaea (haloarchaea) are known to exhibit multiple chromosomes, with one
main chromosome and one or several smaller secondary chromosomes or megaplasmids …

Aquatic viruses are naturally present in the aquatic environment and the number of viruses
is staggering. Various multicellular organisms in aquatic ecosystems may be infected, cross …

Viroids are non-coding circular RNA molecules with rod-like or branched structures. They
are often ribozymes, characterized by catalytic RNA. They can perform many basic functions …

Despite a small genome size, bats have comparable diversity of retroviral and non-retroviral
endogenous sequences to other mammals. These include Class I and Class II retroviral …

Epigenetic modifications can alter the function of genes. The epigenetics changes are
caused by environmental effects, which lead to chemical modifications of the DNA or the …

The debate over whether viruses are living organisms tends to be paradigmatically
determined. The metabolic paradigm denies that they are, while new research evidences …