A unique symbiosome in an anaerobic single-celled eukaryote.

Symbiotic relationships between eukaryotes and prokaryotes played pivotal roles in the evolution of life and drove the emergence of specialized symbiotic structures in animals, plants and fungi. The host-evolved symbiotic structures of microbial eukaryotes - the vast majority of such hosts in nature - remain largely unstudied. Here we describe highly structured symbiosomes within three free-living anaerobic protists (Anaeramoeba spp.

Extreme mitochondrial reduction in a novel group of free-living metamonads.

Metamonads are a diverse group of heterotrophic microbial eukaryotes adapted to living in hypoxic environments. All metamonads but one harbour metabolically altered 'mitochondrion-related organelles' (MROs) with reduced functions, however the degree of reduction varies. Here, we generate high-quality draft genomes, transcriptomes, and predicted proteomes for five recently discovered free-living metamonads.

Influenza A virus NS1 effector domain is required for PA-X-mediated host shutoff in infected cells.

Many viruses inhibit general host gene expression to limit innate immune responses and gain preferential access to the cellular translational apparatus for their protein synthesis. This process is known as host shutoff. Influenza A viruses (IAVs) encode two host shutoff proteins: nonstructural protein 1 (NS1) and polymerase acidic X (PA-X).

Draft genomes of Blastocystis subtypes from human samples of Colombia.

Background: Blastocystis is one of the most common eukaryotic microorganisms colonizing the intestines of both humans and animals, but the conditions under which it may be a pathogen are unclear.

Methods: To study the genomic characteristics of circulating subtypes (ST) in Colombia, we established nine xenic cultures from Blastocystis isolated from human fecal samples, we identified 10 different subtypes, since one sample had a mixed infection. Thus, the genomes of the subtypes ST1 (n = 3), ST2 (n = 1), ST3 (n = 2), ST6 (n = 1), ST7 (n = 1), and ST8 (n = 2) were sequenced using Illumina and Oxford Nanopore Technologies (ONT).

Chromosome-scale assemblies of genomes provide insights into infection-related chromatin reorganization.

The unicellular amoeba is ubiquitous in aquatic environments, where it preys on bacteria. The organism also hosts bacterial endosymbionts, some of which are parasitic, including human pathogens such as and spp. Here we report complete, high-quality genome sequences for two extensively studied strains, Neff and C3.

Genomic analysis finds no evidence of canonical eukaryotic DNA processing complexes in a free-living protist.

Cells replicate and segregate their DNA with precision. Previous studies showed that these regulated cell-cycle processes were present in the last eukaryotic common ancestor and that their core molecular parts are conserved across eukaryotes. However, some metamonad parasites have secondarily lost components of the DNA processing and segregation apparatuses.

RNA-Seq analysis reveals potential regulators of programmed cell death and leaf remodelling in lace plant (Aponogeton madagascariensis).

Background: The lace plant (Aponogeton madagascariensis) is an aquatic monocot that develops leaves with uniquely formed perforations through the use of a developmentally regulated process called programmed cell death (PCD). The process of perforation formation in lace plant leaves is subdivided into several developmental stages: pre-perforation, window, perforation formation, perforation expansion and mature. The first three emerging "imperforate leaves" do not form perforations, while all subsequent leaves form perforations via developmentally regulated PCD.

Re-examination of two diatom reference genomes using long-read sequencing.

Background: The marine diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum are valuable model organisms for exploring the evolution, diversity and ecology of this important algal group. Their reference genomes, published in 2004 and 2008, respectively, were the product of traditional Sanger sequencing. In the case of T.

Heat stress response in the closest algal relatives of land plants reveals conserved stress signaling circuits.

All land plants (embryophytes) share a common ancestor that likely evolved from a filamentous freshwater alga. Elucidating the transition from algae to embryophytes - and the eventual conquering of Earth's surface - is one of the most fundamental questions in plant evolutionary biology. Here, we investigated one of the organismal properties that might have enabled this transition: resistance to drastic temperature shifts.

Nucleomorph Small RNAs in Cryptophyte and Chlorarachniophyte Algae.

The regulation of gene expression and RNA maturation underlies fundamental processes such as cell homeostasis, development, and stress acclimation. The biogenesis and modification of RNA is tightly controlled by an array of regulatory RNAs and nucleic acid-binding proteins. While the role of small RNAs (sRNAs) in gene expression has been studied in-depth in select model organisms, little is known about sRNA biology across the eukaryotic tree of life.

The Inverse Response Law: Theory and Relevance to the Aftermath of Disasters.

The Inverse Care Law is principally concerned with the effect of market forces on health care which create inequities in access to health services through privileging individuals who possess the forms of social capital that are valued within health care settings. The fields of disaster risk reduction need to consider the ways in which inequities, driven by economic and social policy as well as institutional decision-making, create vulnerabilities prior to a disaster, which are then magnified post disaster through entrenched structural differences in access to resources. Drawing on key principles within the Inverse Care Law, the Inverse Response Law refers to the idea that people in lower socio-economic groups are more likely to be impacted and to experience disparities in service provision during the disaster response and recovery phase.

Embryophyte stress signaling evolved in the algal progenitors of land plants.

Streptophytes are unique among photosynthetic eukaryotes in having conquered land. As the ancestors of land plants, streptophyte algae are hypothesized to have possessed exaptations to the environmental stressors encountered during the transition to terrestrial life. Many of these stressors, including high irradiance and drought, are linked to plastid biology.

Genome sequencing reveals metabolic and cellular interdependence in an amoeba-kinetoplastid symbiosis.

Endosymbiotic relationships between eukaryotic and prokaryotic cells are common in nature. Endosymbioses between two eukaryotes are also known; cyanobacterium-derived plastids have spread horizontally when one eukaryote assimilated another. A unique instance of a non-photosynthetic, eukaryotic endosymbiont involves members of the genus Paramoeba, amoebozoans that infect marine animals such as farmed fish and sea urchins.

Heme pathway evolution in kinetoplastid protists.

Background: Kinetoplastea is a diverse protist lineage composed of several of the most successful parasites on Earth, organisms whose metabolisms have coevolved with those of the organisms they infect. Parasitic kinetoplastids have emerged from free-living, non-pathogenic ancestors on multiple occasions during the evolutionary history of the group. Interestingly, in both parasitic and free-living kinetoplastids, the heme pathway-a core metabolic pathway in a wide range of organisms-is incomplete or entirely absent.

The Missing Memory of Canadian Sociology: Reflexive Government and "the Social Science".

The modest literature on the history of Canadian Sociology takes the appearance of a named academic discipline as its object. Canadian Sociology is held to have had some precursors in the 1880s, but really to appear only in the 1920s. It is described as a foreign import and as an activity first of intellectual speculation and moral reform.

Nucleomorph and plastid genome sequences of the chlorarachniophyte Lotharella oceanica: convergent reductive evolution and frequent recombination in nucleomorph-bearing algae.

Background: Nucleomorphs are residual nuclei derived from eukaryotic endosymbionts in chlorarachniophyte and cryptophyte algae. The endosymbionts that gave rise to nucleomorphs and plastids in these two algal groups were green and red algae, respectively. Despite their independent origin, the chlorarachniophyte and cryptophyte nucleomorph genomes share similar genomic features such as extreme size reduction and a three-chromosome architecture.

Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs.

Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans.

Nucleomorph genome sequence of the cryptophyte alga Chroomonas mesostigmatica CCMP1168 reveals lineage-specific gene loss and genome complexity.

Cryptophytes are a diverse lineage of marine and freshwater, photosynthetic and secondarily nonphotosynthetic algae that acquired their plastids (chloroplasts) by "secondary" (i.e., eukaryote-eukaryote) endosymbiosis.

Coral-mucus-associated Vibrio integrons in the Great Barrier Reef: genomic hotspots for environmental adaptation.

Integron cassette arrays in a dozen cultivars of the most prevalent group of Vibrio isolates obtained from mucus expelled by a scleractinian coral (Pocillopora damicornis) colony living on the Great Barrier Reef were sequenced and compared. Although all cultivars showed >99% identity across recA, pyrH and rpoB genes, no two had more than 10% of their integron-associated gene cassettes in common, and some individuals shared cassettes exclusively with distantly-related members of the genus. Of cassettes shared within the population, a number appear to have been transferred between Vibrio isolates, as assessed by phylogenetic analysis.