flagella of unequal length used to create a propulsive current for feeding.[3] As members of Kinetoplastids, they have an evident kinetoplast[4] There was much confusion and debate within the class Kinetoplastid and subclass Bodonidae regarding the classification of the organism, but finally the new genera Neobodo was proposed by Keith Vickerman.[5] Although they are one of the most common flagellates found in freshwater, they are also able to tolerate saltwater[6] Their ability to alternate between both marine and freshwater environments in many parts of the world give them a “cosmopolitan” character.[6] Due to their relatively microscopic size ranging between 4–12 microns, they are further distinguished as heterotrophic nanoflagellates.[3] This small size ratio limits them as bacterivores that swim around feeding on bacteria attached to surfaces or in aggregates.[3]
Etymology
The prefix ‘Neo-’ comes from the ancient Greek word for ‘neos’ which signifies 'young'. Attaching the prefix to the original bodonid species, neobodo literally means a “new” bodonid species.[5]
History of Knowledge
The order Neobodonida was proposed by a researcher, Keith Vickerman, based on significant characteristics that differed from the original bodonid species.
polyphyletic in the trees rooted using the traditional, distant outgroup sequences.[5]
As a result, the classification of the class Kinetoplastea was divided as two new subclasses:
Through this process, Neobodo was created as a new genus, along with the revision of the classification of species formerly included in the genus Bodo and the amendment of the genus Parabodo.[5]
Description
The new genus Neobodo is characterized as solitary
cytopharynx supported by a prismatic rod of microtubules.[5]
Neobodo cells are usually elongate and
proximal part of the posterior flagellum is accompanied with a paraxial rod and sometimes non-tubular mastigonemes.[5] The cells use their posterior flagellum and rotate around their longitudinal axes to swim and glide along in rapid darts of straight lines.[7]
Along with their two flagella, they have two nearly parallel
Bodonid flagellates (class Kinetoplastea) are abundant, free-living
euphotic zone of different marine areas.[3] Areas include the Mediterranean Sea, Norwegian Sea, the Indian Ocean and around the Antarctic Peninsula.[3] Throughout the numerous oceans, large fractions of small heterotrophic flagellates with few morphological features remain unidentified.[3] Therefore there is a high possibility that there are many bodonids among the unidentified that have not yet been studied.[3]
Although Neobodo are surface organisms, typically found in surface waters, studies have shown their ability to tolerate deep water conditions.
microbes from the surface of the ocean are continuously transported to deeper areas.[6] The vast majority of the marine environment consists of dark, cold, high-pressure environments, which increases with depth.[6] When cultures of Neobodo were isolated from surface waters and were put in different deep-sea temperatures and pressures, the abundance of protists declined in all treatments, with a significantly greater rate of mortality under combined cold temperature and high pressure conditions than in the cold temperature-only conditions.[6] However, an average of 6.1% of N. designis cells survived in the high pressure treatments, indicating that some fraction of sinking protists can survive transport to the deep ocean.[6] In addition, after a period of acclimation, positive growth rates were measured in some cases.[6] This suggests that surface-adapted flagellates can not only survive under deep-sea conditions but are able to reproduce and potentially provide seed populations in cold, high-pressure environments.[6] Although Neobodo are not abundant in the deep oceans, they are capable of surviving in the deep waters, tolerating high pressure and low temperature conditions.[6]
Feeding
Neobodo are free-living and active microbial predators that swim around and feed on prey in aquatic ecosystems.
pseudopod-like structure (pharynx) to detach bacteria.[3] Within this feeding mechanism, further variability in terms of feeding behavior and selection strategies can be observed among different species.[3]
Practical importance
Despite the
fibers and coarser tunic matrices.[8] However, the pathogenesis is unclear and is still an area of research.[8]
List of species (or of lower taxonomic units)
Despite the considerable interest in free-living bodonids, their true
rRNA gene primers were used to test Neobodo’s global distribution and genetic diversity.[7] The non-overlap between environmental DNA sequences and those from cultures suggests that there are hundreds, possibly thousands, of different rRNA gene sequences of free-living Neobodo species globally.[7]
^ abcdef"Neobodo". NCBI taxonomy. Bethesda, MD: National Center for Biotechnology Information. Retrieved 19 April 2018.
^ abcdefghijklmnopKirchman, D. 2008: Microbial ecology of the oceans / [edited by] David L. Kirchman. (2nd ed.).
^ abcdefghijklmnoTikhonenkov, D. V., Janouškovec, J., Keeling, P. J., and Mylnikov, A. P. 2016: The Morphology, Ultrastructure and SSU rRNA Gene Sequence of a New Freshwater Flagellate, Neobodo borokensis n. sp. (Kinetoplastea, Excavata). The Journal Of Eukaryotic Microbiology, 63 :220–232. DOI:10.1111/jeu.12271
^ abcdefghijklmnopqMoreira, David, et al. 2004: An Updated View of Kinetoplastid Phylogeny Using Environmental Sequences and a Closer Outgroup: Proposal for a New Classification of the Class Kinetoplastea. International Journal of Systematic and Evolutionary Microbiology, 54: 1861–75. DOI:10.1099/ijs.0.63081-0
^ abcdefghijklmMorgan-Smith, D., Garrison, C. E., and Bochdansky, A. B. 2013: Mortality and survival of cultured surface-ocean flagellates under simulated deep-sea conditions. Journal of Experimental Marine Biology and Ecology, 445: 13–20. DOI: 10.1016/j.jembe.2013.03.017
^ abcdefghVon Der Heyden, S., and Cavalier-Smith, T. 2005: Culturing and Environmental DNA Sequencing Uncover Hidden Kinetoplastid Biodiversity and a Major Marine Clade within Ancestrally Freshwater Neobodo Designis. International Journal of Systematic and Evolutionary Microbiology, 55: 2605–2621. DOI: 10.1099/ijs.0.63606-0
^ abcdJang, H.B., Kim, Y. K., Del Castillo, C. S., Nho, S. W., Cha, I. S., and Park, S. B. 2012: RNA-Seq-Based Metatranscriptomic and Microscopic Investigation Reveals Novel Metalloproteases of Neobodo sp. as Potential Virulence Factors for Soft Tunic Syndrome in Halocynthia roretzi. PLoS ONE, 7(12): e52379. DOI: 10.1371/journal.pone.0052379
