Hunting Down Giant Viruses That Attack Tiny Algae potentially threatening Earth's oxygen production

Horror stories from the oceans! What kind of symbiosis is this?

"... Giant viruses inhabiting the oceans infect, among others, various species of single-celled algae, photosynthetic organisms that are responsible for about half of the Earth’s oxygen production and around half of the global carbon fixation. Viral infection can cause a rapid collapse of algal blooms – accumulations of algae stretching across tens of thousands of kilometers in the ocean – and this can, in turn, substantially affect extensive marine, atmospheric and terrestrial ecosystems. ..."

From the abstract:

"Giant viruses (phylum Nucleocytoviricota) are globally distributed in aquatic ecosystems. They play fundamental roles as evolutionary drivers of eukaryotic plankton and regulators of global biogeochemical cycles. However, we lack knowledge about their native hosts, hindering our understanding of their life cycle and ecological importance. In the present study, we applied a single-cell RNA sequencing (scRNA-seq) approach to samples collected during an induced algal bloom, which enabled pairing active giant viruses with their native protist hosts. We detected hundreds of single cells from multiple host lineages infected by diverse giant viruses. These host cells included members of the algal groups Chrysophycae and Prymnesiophycae, as well as heterotrophic flagellates in the class Katablepharidaceae. Katablepharids were infected with a rare Imitervirales-07 giant virus lineage expressing a large repertoire of cell-fate regulation genes. Analysis of the temporal dynamics of these host–virus interactions revealed an important role for the Imitervirales-07 in controlling the population size of the host Katablepharid population. Our results demonstrate that scRNA-seq can be used to identify previously undescribed host–virus interactions and study their ecological importance and impact."

Hunting Down Giant Viruses That Attack Tiny Algae - Environment | Weizmann Wonder Wander - News, Features and Discoveries "A mysterious menace lurks in the oceans, threatening algal blooms. Weizmann Institute researchers have developed a new way to track the culprit – giant viruses – and identify their traces in specific types of tiny algae that they attack"

Single-cell RNA-seq of the rare virosphere reveals the native hosts of giant viruses in the marine environment (no public access)

How blooms collapse: Four giant hexagon-shaped viruses that multiplied within a single-celled alga (rough texture on the right) are about to infect other algal cells. Three viruses are intact and ready for action, and one (white) lacks DNA.

The line connecting a giant virus to a tiny alga: Families of single-celled algae (left) and the giant viruses (right) that they host, as discovered in the study