Tsukubamonas

Tsukubamonas is a unicellular heterotrophic, biflagellated excavate of the Discoba clade (along with jakobids, euglenozoans and percolozoans) with only one species known, Tsukubamonas globosa. It inhabits fresh-water, feeds on bacteria, and can exist as a vegetative cell or cyst. The cells are characterised with a spherical or semi-spherical shape, are highly vacuolated with thin subsurface vesicles and the absence of a contractile vacuole, tubular cristae in its mitochondria, and two flagella of an apparatus with five main structures (four basal bodies, three major microtubule roots, four major fibres, one microtubule organization center, and several internal microtubules). Tsukubamonas is notable for having a backwards right root, a differentiation of its anterior root orientation, and for having a lack of a left root. Other notable differences are in the morphology of its singlet root and associated fibre, the lack of flagella vanes, and in its cytoskeletal structure. The research has currently acknowledged its placement within the Discoba clade as its own individual group, with its mitochondrial genome to be around 48,643 base pairs long. == Etymology == “Tsukuba” is derived from the geographical location of the University of Tsukuba, Japan, where th organism was found. “Monas” is a suffix commonly used to describe single-celled organisms within taxonomic rank, originating from Ancient Greek word "μονάς" (monás), meaning "unit" or "single". == History of knowledge == The genus was first discovered in Hyoutaro pond at the University of Tsukuba, Japan in October, 2002. Providing a general idea of its phylogenetic position, they determined the genus to be categorized within the supergroup, Excavata, due to the presence of a ventral feeding groove. However, with a number of differing characteristics from the supergroup, they further used SSU rDNA phylogeny analysis to determine the precise positioning. Although this method provided no results of statistical significance, a multigene phylogeny analysis using 5 protein datasets was able to place the group ambiguously under the Discoba clade along with Jakobids, Euglenozoans, and Heteroloboseans. The novelty of the morphological features provided lead to the classification of its own new taxa, the Tsukubamonadidae n. fam. and Tsukubamonadida n. ord. Tsukubamonas globosa is currently the only species in the genus. Since the initial collection from Hyoutaropond, T. globosa has never been found again. An established strain has been created and maintained through a small aliquot of water sample and URO1YT(1/10) media, along with bacterial prey.

From the works of Yabuki et al., further research has been done to complete the mitochondrial genome sequence and to determine its evolutionary relationship to other Discobids. From this, Tsukubamonas is currently recognized as an independent discobid lineage.