GeekooThey infect algae, rewire photosynthesis, and shape ocean life from the shadows. Meet the newly discovered giants of the sea. #GiantViruses #OceanScience #MarineEcology
https://geekoo.news/the-giants-that-rule-the-microbial-ocean/
Frank AylwardGiant virus encodes key piece of protein-making machinery of cellular life
"Viruses are integral to the functioning of ocean ecosystems, influencing biological productivity, shifting community interactions, and driving evolutionary change,"
https://phys.org/news/2024-12-giant-virus-encodes-key-piece.html
Giant virus encodes key piece of protein-making machinery of cellular life
Researchers at the University of Hawai'i at Mānoa have discovered that a virus, FloV-SA2, encodes one of the proteins needed to make ribosomes, the central engines in all cells that translate genetic information into proteins, the building blocks of life. This is the first eukaryotic virus (a virus that infects eukaryotes, such as plants, animals, fungi) found to encode such a protein.
Lukas VFN 🇪🇺Hunting down giant #viruses that attack tiny algae https://phys.org/news/2024-09-giant-viruses-tiny-algae.html
Single-cell RNA-seq of the rare #virosphere reveals the native hosts of giant viruses in the marine environment https://www.nature.com/articles/s41564-024-01669-y
"#GiantViruses inhabiting the oceans infect, among others, various species of single-celled #algae... Viral infection can cause a rapid collapse of #AlgalBlooms"
Hunting down giant viruses that attack tiny algae
They were said to come from outer space, and there were even claims that they were actually bacteria and that they undermined the very definition of viruses. Giant viruses, nicknamed "giruses," contain enormous quantities of genetic material—up to 100 times more than other viruses—and some are larger than certain bacteria.
ISEPNew #ISEPpapers! Genomic analyses of Symbiomonas scintillans show no evidence for endosymbiotic #bacteria but does reveal the presence of #GiantViruses https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1011218 #protists #symbiosis #viruses #genomics #microbes @PLOS by Anna Cho et al.
Genomic analyses of Symbiomonas scintillans show no evidence for endosymbiotic bacteria but does reveal the presence of giant viruses
Author summary Endosymbiotic bacteria are found in a wide variety of hosts across the tree of eukaryotes and have been proposed to be evolutionarily and ecologically significant, but in most cases, we know little to nothing about them. This is exemplified by the stramenopile flagellate Symbiomonas scintillans, where the bacterial endosymbiont that gave the genus its name remains unidentified and has no known function. Here we used multiple genomic sequencing methods on two strains of S. scintillans, and showed absence of the endobacteria belonging to common endosymbiotic lineages. Instead, we identified giant viruses similar to those infecting prasinophyte green algae. Although further experiments are needed to verify the nature of the viral association with S. scintillans, our study is reminiscent of how the first mimivirus (named for mimicking gram-negative bacteria) was discovered, and we speculate similar discoveries will follow with ever-increasing genomic data of protists.
michael4-JUN-2024
#GiantViruses found on #Greenland ice sheet
The viruses probably regulate the growth of snow #algae on the ice by infecting them. Knowing how to control these #viruses could help us reduce some of the ice from melting.
<< that's fascinating but I really don't think they are going to stop the #ClimateCatastrophe for us.
https://www.eurekalert.org/news-releases/1047048 #science #ecology #environment #microbiology
Giant viral signatures on the Greenland ice sheet
Giant viral signatures on the Greenland ice sheet - Microbiome
Background Dark pigmented snow and glacier ice algae on glaciers and ice sheets contribute to accelerating melt. The biological controls on these algae, particularly the role of viruses, remain poorly understood. Giant viruses, classified under the nucleocytoplasmic large DNA viruses (NCLDV) supergroup (phylum Nucleocytoviricota), are diverse and globally distributed. NCLDVs are known to infect eukaryotic cells in marine and freshwater environments, providing a biological control on the algal population in these ecosystems. However, there is very limited information on the diversity and ecosystem function of NCLDVs in terrestrial icy habitats. Results In this study, we investigate for the first time giant viruses and their host connections on ice and snow habitats, such as cryoconite, dark ice, ice core, red and green snow, and genomic assemblies of five cultivated Chlorophyta snow algae. Giant virus marker genes were present in almost all samples; the highest abundances were recovered from red snow and the snow algae genomic assemblies, followed by green snow and dark ice. The variety of active algae and protists in these GrIS habitats containing NCLDV marker genes suggests that infection can occur on a range of eukaryotic hosts. Metagenomic data from red and green snow contained evidence of giant virus metagenome-assembled genomes from the orders Imitervirales, Asfuvirales, and Algavirales. Conclusion Our study highlights NCLDV family signatures in snow and ice samples from the Greenland ice sheet. Giant virus metagenome-assembled genomes (GVMAGs) were found in red snow samples, and related NCLDV marker genes were identified for the first time in snow algal culture genomic assemblies; implying a relationship between the NCLDVs and snow algae. Metatranscriptomic viral genes also aligned with metagenomic sequences, suggesting that NCLDVs are an active component of the microbial community and are potential “top-down” controls of the eukaryotic algal and protistan members. This study reveals the unprecedented presence of a diverse community of NCLDVs in a variety of glacial habitats dominated by algae.
A giant virus infecting the amoeboflagellate Naegleria
A giant virus infecting the amoeboflagellate Naegleria - Nature Communications
This is the first report on a virus infecting the amoeboflagellate Naegleria, including the lethal human pathogen N. fowleri. The new virus isolate, Catovirus naegleriensis (Naegleriavirus, NiV), shows hallmarks of giant viruses (Nucleocytoviricota) and unique adaptations to its protist host.
Another interesting study suggesting that giant viruses can control phototaxis in their hosts during infection
"Hijacking of internal calcium dynamics by intracellularly residing viral rhodopsins"
"... we show here that light irradiation reversibly modified tail movements of OLPVR1-expressing frog tadpoles."
Hijacking of internal calcium dynamics by intracellularly residing viral rhodopsins - Nature Communications
Rhodopsins are ubiquitous light-driven membrane proteins that have diverse functions in nature, and value as optogenetics tools. Here the authors characterise type 1 viral channelrhodopsins, showing that they regulate intracellular calcium and can be used for the photocontrol of muscle contraction in vivo.
Gene duplication as a major force driving the genome expansion in some giant viruses
Kratosvirus quantuckense: the history and novelty of an algal bloom disrupting virus and a model for giant virus research
Kratosvirus quantuckense: the history and novelty of an algal bloom disrupting virus and a model for giant virus research
Since the discovery of the first “giant virus,” particular attention has been paid toward isolating and culturing these large DNA viruses through Acanthamoeba spp. bait systems. While this method has allowed for the discovery of plenty novel viruses in the Nucleocytoviricota, environmental -omics-based analyses have shown that there is a wealth of diversity among this phylum, particularly in marine datasets. The prevalence of these viruses in metatranscriptomes points toward their ecological importance in nutrient turnover in our oceans and as such, in depth study into non-amoebal Nucleocytoviricota should be considered a focal point in viral ecology. In this review, we report on Kratosvirus quantuckense (née Aureococcus anophagefferens Virus), an algae-infecting virus of the Imitervirales. Current systems for study in the Nucleocytoviricota differ significantly from this virus and its relatives, and a litany of trade-offs within physiology, coding potential, and ecology compared to these other viruses reveal the importance of K. quantuckense. Herein, we review the research that has been performed on this virus as well as its potential as a model system for algal-virus interactions.