Andrew J. Roger | |
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Academic background | |
Alma mater | University of British Columbia, Dalhousie University |
Influences | Ford Doolittle |
Academic work | |
Institutions | Dalhousie University |
Main interests | Eukaryotic organisms,biology and evolution of mitochondria,hydrogenosomes and mitosomes,comparative genomics of unicellular eukaryotes,modeling the evolution of genes and genomes |
Website | https://medicine.dal.ca/departments/department-sites/biochemistry-molecular-biology/our-people/faculty/roger.html |
Andrew J. Roger is a Canadian-Australian molecular biologist and evolutionary bioinformatician. He is currently a professor in the Department of Biochemistry and Molecular Biology at Dalhousie University and was the founding director (from 2008-2017) of the inter-departmental Centre for Comparative Genomics and Evolutionary Bioinformatics (CGEB). [1]
Roger received his B.Sc from the University of British Columbia and his PhD from Dalhousie University. Roger was elected as a fellow of the Royal Society of Canada in 2012 [2] for his work on eukaryotic superkingdoms,his work on the evolution of mitochondrion-related organelles in anaerobic protists and his contribution to investigating and improving phylogenetic models [3]
A former student of Ford Doolittle,Roger's research focuses on the 'deep' Tree of Life,especially determining the super-kingdom-level relationships amongst eukaryotes and clarifying the nature of the last eukaryotic common ancestor (LECA). [4] Using phylogenomic approaches Roger's group elucidates the patterns and process of genome evolution in eukaryotic microbes. His research also addresses the evolutionary origin of mitochondria,hydrogenosomes,and mitosomes, [5] [6] [7] the role of lateral (horizontal) gene transfer in eukaryotic genome evolution [8] [9] and how anaerobic parasites evolved from free-living ancestors.
Symbiogenesis is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria,plastids such as chloroplasts,and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria,while chloroplasts are thought to be related to cyanobacteria.
Excavata is an extensive and diverse but paraphyletic group of unicellular Eukaryota. The group was first suggested by Simpson and Patterson in 1999 and the name latinized and assigned a rank by Thomas Cavalier-Smith in 2002. It contains a variety of free-living and symbiotic protists,and includes some important parasites of humans such as Giardia and Trichomonas. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They were distinguished from other lineages based on electron-microscopic information about how the cells are arranged. They are considered to be a basal flagellate lineage.
The metamonads are a large group of flagellate amitochondriate microscopic eukaryotes. Their composition is not entirely settled,but they include the retortamonads,diplomonads,and possibly the parabasalids and oxymonads as well. These four groups are all anaerobic,occurring mostly as symbiotes or parasites of animals,as is the case with Giardia lamblia which causes diarrhea in mammals.
Amorphea is a taxonomic supergroup that includes the basal Amoebozoa and Obazoa. That latter contains the Opisthokonta,which includes the Fungi,Animals and the Choanomonada,or Choanoflagellates. The taxonomic affinities of the members of this clade were originally described and proposed by Thomas Cavalier-Smith in 2002.
The retortamonads are a small group of flagellates,most commonly found in the intestines of animals as commensals,although a free-living species called the Chilomastix cuspidata exists. They are grouped under the taxon,Archezoa. They are usually around 5-20 μm in length,and all of their small subunit ribosomal RNA gene sequences are very similar to each other. There are two genera:Retortamonas with two flagella,and Chilomastix with four. In both cases there are four basal bodies anterior to a prominent feeding groove,and one flagellum is directed back through the cell,emerging from the groove.
The Oxymonads are a group of flagellated protists found exclusively in the intestines of animals,mostly termites and other wood-eating insects. Along with the similar parabasalid flagellates,they harbor the symbiotic bacteria that are responsible for breaking down cellulose. There is no evidence for presence of mitochondria in oxymonads and 3 species have been shown to completely lack any molecular markers of mitochondria.
A mitosome is a mitochondrion-related organelle (MRO) found in a variety of parasitic unicellular eukaryotes,such as members of the supergroup Excavata. The mitosome was first discovered in 1999 in Entamoeba histolytica, an intestinal parasite of humans,and mitosomes have also been identified in several species of Microsporidia and in Giardia intestinalis.
Alphaproteobacteria is a class of bacteria in the phylum Pseudomonadota. The Magnetococcales and Mariprofundales are considered basal or sister to the Alphaproteobacteria. The Alphaproteobacteria are highly diverse and possess few commonalities,but nevertheless share a common ancestor. Like all Proteobacteria,its members are gram-negative,although some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable.
Telonemia is a phylum of microscopic eukaryotes commonly known as telonemids. They are unicellular free-living flagellates with a unique combination of cell structures,including a highly complex cytoskeleton unseen in other eukaryotes.
Breviata anathema is a single-celled flagellate amoeboid eukaryote,previously studied under the name Mastigamoeba invertens. The cell lacks mitochondria,much like the pelobionts to which the species was previously assigned,but has remnant mitochondrial genes,and possesses an organelle believed to be a modified anaerobic mitochondrion,similar to the mitosomes and hydrogenosomes found in other eukaryotes that live in low-oxygen environments.
Anaeromonadea,also known as Preaxostyla,is a class of excavate protists,comprising the oxymonads,Trimastix,and Paratrimastix. This group is studied as a model system for reductive evolution of mitochondria,because it includes both organisms with anaerobic mitochondrion-like organelles,and those that have completely lost their mitochondria.
Malawimonas is genus of unicellular,heterotrophic flagellates with uncertain phylogenetic affinities. They have variably being assigned to Excavata and Loukozoa. Recent studies suggest they may be closely related to the Podiata.
Jakobids are an order of free-living,heterotrophic,flagellar eukaryotes in the supergroup Excavata. They are small,and can be found in aerobic and anaerobic environments. The order Jakobida,believed to be monophyletic,consists of only twenty species at present,and was classified as a group in 1993. There is ongoing research into the mitochondrial genomes of jakobids,which are unusually large and bacteria-like,evidence that jakobids may be important to the evolutionary history of eukaryotes.
Holozoa is a clade of organisms that includes animals and their closest single-celled relatives,but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms,including around 300 unicellular species. It consists of various subgroups,namely Metazoa and the protists Choanoflagellata,Filasterea,Pluriformea and Ichthyosporea. Along with fungi and some other groups,Holozoa is part of the Opisthokonta,a supergroup of eukaryotes. Choanofila was previously used as the name for a group similar in composition to Holozoa,but its usage is discouraged now because it excludes animals and is therefore paraphyletic.
The eukaryotes constitute the domain of Eukarya or Eukaryota,organisms whose cells have a membrane-bound nucleus. All animals,plants,fungi,and many unicellular organisms are eukaryotes. They constitute a major group of life forms alongside the two groups of prokaryotes:the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms,but given their generally much larger size,their collective global biomass is much larger than that of prokaryotes.
The Magnetococcales were an order of Alphaproteobacteria,but now the mitochondria are considered as sister to the alphaproteobactera,together forming the sister the marineproteo1 group,together forming the sister to Magnetococcidae.
Cryptista is a clade of alga-like eukaryotes. It is most likely related to Archaeplastida which includes plants and many algae,within the larger group Diaphoretickes.
Obazoa is a proposed sister clade of Amoebozoa. The term Obazoa is based on the OBA acronym for Opisthokonta,Breviatea,and Apusomonadida,the group's three constituent clades.
A supergroup,in evolutionary biology,is a large group of organisms that share one common ancestor and have important defining characteristics. It is an informal,mostly arbitrary rank in biological taxonomy that is often greater than phylum or kingdom,although some supergroups are also treated as phyla.
Paratrimastix pyriformis is a species of free-living (non-parasitic) anaerobic freshwater bacteriovorous flagellated protists formerly known as Trimastix pyriformis and Tetramitus pyriformis.