Comparative transcriptomics reveals the molecular toolkit used by an algivorous protist for cell wall perforation.

Microbial eukaryotes display a stunning diversity of feeding strategies, ranging from generalist predators to highly specialized parasites. The unicellular "protoplast feeders" represent a fascinating mechanistic intermediate, as they penetrate other eukaryotic cells (algae and fungi) like some parasites but then devour their cell contents by phagocytosis. Besides prey recognition and attachment, this complex behavior involves the local, pre-phagocytotic dissolution of the prey cell wall, which results in well-defined perforations of species-specific size and structure.

The effective family size of immigrant founders predicts their long-term demographic outcome: From Québec settlers to their 20th-century descendants.

Population history reconstruction, using extant genetic diversity data, routinely relies on simple demographic models to project the past through ascending genealogical-tree branches. Because genealogy and genetics are intimately related, we traced descending genealogies of the Québec founders to pursue their fate and to assess their contribution to the present-day population. Focusing on the female and male founder lines, we observed important sex-biased immigration in the early colony years and documented a remarkable impact of these early immigrants on the genetic make-up of 20th-century Québec.

Historical human remains identification through maternal and paternal genetic signatures in a founder population with extensive genealogical record.

Objectives: We describe a method to identify human remains excavated from unmarked graves in historical Québec cemeteries by combining parental-lineage genetic markers with the whole-population genealogy of Québec contained in the BALSAC database.

Materials And Methods: The remains of six men were exhumed from four historical cemeteries in the province of Québec, Canada. DNA was extracted from the remains and genotyped to reveal their mitochondrial and Y-chromosome haplotypes, which were compared to a collection of haplotypes of genealogically-anchored modern volunteers.

Recent Advances in Halophilic Protozoa Research.

Most research on microorganisms adapted to hypersaline habitats has focused on Archaea and Bacteria, with microbial eukaryotes receiving much less attention. Over the past 15 yr, our knowledge of phagotrophic microbial eukaryotes, i.e.

Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers.

The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga . By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.

Mitochondrial Genome Evolution and a Novel RNA Editing System in Deep-Branching Heteroloboseids.

Discoba (Excavata) is an evolutionarily important group of eukaryotes that includes Jakobida, with the most bacterial-like mitochondrial genomes known, and Euglenozoa, many of which have extensively fragmented mitochondrial genomes. However, little is known about the mitochondrial genomes of Heterolobosea, the third main group of Discoba. Here, we studied two heteroloboseids-an undescribed amoeba "BB2" and Pharyngomonas kirbyi.

Osmoadaptative Strategy and Its Molecular Signature in Obligately Halophilic Heterotrophic Protists.

Halophilic microbes living in hypersaline environments must counteract the detrimental effects of low water activity and salt interference. Some halophilic prokaryotes equilibrate their intracellular osmotic strength with the extracellular milieu by importing inorganic solutes, mainly potassium. These "salt-in" organisms characteristically have proteins that are highly enriched with acidic and hydrophilic residues.

Winter bloom of a rare betaproteobacterium in the Arctic Ocean.

Extremely low abundance microorganisms (members of the "rare biosphere") are believed to include dormant taxa, which can sporadically become abundant following environmental triggers. Yet, microbial transitions from rare to abundant have seldom been captured in situ, and it is uncertain how widespread these transitions are. A bloom of a single ribotype (≥99% similarity in the 16S ribosomal RNA gene) of a widespread betaproteobacterium (Janthinobacterium sp.

Amoeba stages in the deepest branching heteroloboseans, including Pharyngomonas: evolutionary and systematic implications.

The taxon Heterolobosea (Excavata) is a major group of protists well known for its diversity of life stages. Most are amoebae capable of transforming into flagellates (amoeboflagellates), while others are known solely as flagellates or solely as amoebae. The deepest-branching heterolobosean taxon confirmed previously, Pharyngomonas, was generally assumed to be a pure flagellate, suggesting that the amoeba form arose later in the evolution of Heterolobosea sensu lato.

Vertical distribution of microbial communities in a perennially stratified Arctic lake with saline, anoxic bottom waters.

Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada.

Microbes in high arctic snow and implications for the cold biosphere.

We applied molecular, microscopic, and culture techniques to characterize the microbial communities in snow and air at remote sites in the Canadian High Arctic (Ward Hunt Island, Ellesmere Island, and Cornwallis Island, latitudes 74 to 83(o)N). Members of the Bacteria and Eukarya were prevalent in the snow, and their small subunit (SSU) rRNA gene signatures indicated strong local aerial transport within the region over the preceding 8 months of winter snowpack accumulation. Many of the operational taxonomic units (OTUs) were similar to previously reported SSU rRNA gene sequences from the Arctic Ocean, suggesting the importance of local aerial transport processes for marine microbiota.