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Ross Waller

Cell evolution – novel chromatin biology, remodelling of the cytoskeleton for parasitism, and organellogenesis in diverse eukaryotes


Microbial eukaryotes (protists) go unseen by most but represent the majority of eukaryotic biochemical, molecular and cellular diversity, and drive some of the most important biological processes on the planet. These include contributing half of global primary production and food webs, as well as acting as important disease agents in humans and other organisms (e.g. malaria, toxoplasmosis, trypanosomiasis, giardiasis). Protists also represent many of the major evolutionary transitions that have shaped modern eukaryotes. We study a range of important protist groups in order to better understand cell evolution, and to illuminate the diversity of cellular processes and machineries that define the eukaryotic world.

Two current research themes in the lab are: 1) investigating a novel, histone-independent chromatin organisation found in dinoflagellate algae; and 2) investigating the composition and architecture of the cytoskeleton in apicomplexan parasites, and its role in parasite invasion and proliferation.

Dinoflagellates are a remarkable phylum that present a new view of chromatin biology. They have abandoned the major function of histones in the organisation and regulation of the nuclear genome. Histones have been displaced by a new protein that was gained from an ancient viral infection. We are investigating the novel chromatin biology of this system: the organisation of these genomes; their interaction with the new viral nucleoprotein; and the retained function of a highly modified residual population of histones.

Apicomplexan parasites cause diseases such as malaria and toxoplasmosis, and are superbly evolved to non-destructively invade their host cells where they proliferate. They have remodelled a common cytoskeletal platform shared with related phyla, dinoflagellates and ciliates, to achieve these fiendish tasks. We are deconstructing the apicomplexan cytoskeleton using the genetically tractable model system Toxoplasma gondii to better understand these disease processes.

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Key publications:

Gornik, S.G., Febrimarsa, Cassin, A., MacRae, J.I., Ramaprasad, A., Rchiad, Z., McConville, M.J., Bacic, A., McFadden, G.I., Pain, A. and Waller, R.F. (2015) Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate. PNAS in press

Katris, N.K., van Dooren, G.G., McMillan, P.J., Hanssen, E., Tilley, L. and Waller, R.F. (2014) The apical complex provides a regulated gateway for secretion of invasion factors in Toxoplasma. PLOS Pathog. 10: e1004074

Gornik, S.G., Ford, K.L., Mulhern, T.D., Bacic, A., McFadden, G.I. and Waller, R.F. (2012) Loss of nucleosomal DNA condensation coincides with appearance of a novel nuclear protein in dinoflagellates. Curr. Biol. 22(24): 2303-12

Gould. S.B., Kraft, L.G.K, van Dooren, G.G., Goodman, C.D., Ford, K.L., Cassin, A.M., Bacic, A. McFadden, G.I. and Waller, R.F. (2011) Ciliate pellicular proteome identifies novel protein families with characteristic repeat motifs that are common to Alveolates. Mol. Biol. Evol. 28: 1319-31

Gould, S.B., Tham, W-H., Cowman, A.F., McFadden, G.I. and Waller, R.F. (2008)  Alveolins, a new family of cortical proteins that define the protist infrakingdom Alveolata. Mol. Biol. Evol. 25:1219-30