Research

Protistan Cell Biology and Evolution

Our research focuses on some of the most ancient, distinctive, free-living eukaryotic protists, the euglenoid flagellates (Euglenida). Often cited as the prototypical "neither plant nor animal", Euglena is known to virtually every grade schooler and is arguably one of the most widely recognized protists in the world. In fact, Euglena was one of the first protozoans ever seen by Leeuwenhoek. Despite these distinctions, the vast majority of euglenoids are poorly known even among biologists who regularly encounter them in a multitude of environments.

Euglenoids are critically positioned in the evolutionary scheme of eukaryotes and may represent some of the first eukaryotes to possess a mitochondrion. They are most closely related with the kinetoplastids, a group of flagellates that cause many human illnesses including, African Sleeping sickness and Chagas disease. For over a decade, we have been conducting a systematic investigation of the euglenoids using a combined ultrastructural and molecular approach. We have investigated: 1) the ultrastructure of the flagellar apparatus, 2) flagellar motility, 3) mitosis and cytokinesis, 4) the structure and mechanism of operation of the complex feeding apparatus, and 5) phagotrophy/feeding.

The second major aspect of this research is a comparative study of the primary and secondary structure of the small subunit rRNA from euglenoids. Because of its highly conserved nature, the rRNA molecule can be used effectively to infer phylogenetic relationships among organisms ranging from prokaryotes to man. The SSU rRNA gene is amplified, and cycle sequenced. Sequences are generated, aligned based on primary and secondary structure of the rRNA molecule, and compared. The phylogenetic relationships among the taxa are then inferred. Data from the combined ultrastructural and molecular studies are used to deduce evolutionary relationships among taxa, and to determine the morphological and molecular features which characterize these ancient eukaryotes.

A complete introduction to the euglenoid flagellates is presented our NSF sponsored website entitled the The Euglenoid Project.

Publications (1996-present)

Müllner A. N., Angeler D. G., Samuel R., Linton E. W. and Triemer R. E. 2001. Phylogenetic analysis of phagotrophic, phototrophic and osmotrophic euglenoids by using nuclear 18S rDNA sequence. Int. J. Syst. Evol. Microbiol. 51, 783-791.  

Linton, E. and Triemer, R. E. 2001. Reconstruction of the flagellar apparatus in Ploeotia costata (Euglenophyta) and its relationship to other euglenoid flagellar apparatuses. J. Eukaryot. Microbiol.  48:88-94.

 Shin, W. and R. E. Triemer. 2001.  Ultrastructure of the basal body complex and putative vestigial feeding apparatus in Phacus pleuronectes (Euglenophyceae). J. Phycol. 37:913-92.

Leander, B. S.,Triemer R. E. and Farmer, M.A. 2001. Character evolution in heterotrophic euglenids. European Journal of Protistology 37: 337-356.

E. Linton, A. Nudelman, V. Conforti and R. E. Triemer. 2000. A molecular analysis of the euglenophytes using small subunit rDNA  J. Phycol. 36:740-74.  

E. Linton, D. Hittner, C. L. Lewandowski, T. Auld and R. E. Triemer. 1999. A molecular study of euglenoid phylogeny using small subunit rDNA. J. Euk. Microbiol. 46:217-223.

E. Linton and R. E. Triemer. 1999. Reconstruction of the feeding apparatus of Ploeotia costata (Euglenophyta) and its relationships to other euglenoid feeding apparatuses. J. Phycol. 35:313-24.

Triemer, R. E. 1997. Feeding in Peranema trichophorum revisited. J. Phycol. 33:649-654.

Montegut-Felkner, A. E. and R. E. Triemer. 1997. Phylogenetic relationships of select euglenoid genera based on morphological and molecular data. J. Phycol. 33:512-519.

Montegut-Felkner, A. E. and R. E. Triemer. 1996. Phylogeny of Diplonema ambulator (Larsen and Patterson). I. Homologies of the feeding apparatus. Europ. J. Protistology. 32:64-76.