Nassula is agenus ofunicellularciliates, belonging to the classNassophorea. Like other members of the class,Nassula possesses a basket-like feeding apparatus (nasse, orcyrtos) made up of cytopharyngeal rods (nematodesmata), which are themselves composed of closely packedmicrotubules.[1][2][3]Nassula use this structure to ingestfilamentous cyanobacteria, drawing individual strands of blue-green algae through thecytopharynx and into the body of the cell, where they are digested. As the algae are broken down, they can take on a variety of bright colours, which giveNassula a distinctive, variegated appearance under the microscope.
The body is ovoid to elongate, and uniformly ciliated, with a single macronucleus and a partial hypostomial frange (synhymenium) running from the left side of the cell to the oral aperture.[4] When food is scarce, members of the genus have the ability to become dormant by forming amicrobial cyst. Excystment can be induced by exposure to a medium inoculated with wild bacteria.[5]
Nassula reproduce asexually, byfission.[6] During reproduction, the cell is divided transversally. As in most ciliates (with the exception of theKaryorelictea) themacronucleus splits, during division, and themicronuclei also undergomitosis.
While fission is an asexual process, it may be preceded byconjugation, during which compatible mating individuals come together and transfer genetic material across a cytoplasmic link. In conjugation, the micronuclei of each cell undergomeiosis, andhaploid micronuclei are then exchanged from one cell to the other. After sexual exchange has occurred, both conjugants will divide by fission.[7]
^Vigues, Bernard; Blanchard, Marie-Pierre; Bouchard, Philippe (1999). "Centrin-like filaments in the cytopharyngeal apparatus of the ciliatesNassula andFurgasonia: evidence for a relationship with microtubular structures".Cell Motility and the Cytoskeleton.43 (1):72–81.doi:10.1002/(SICI)1097-0169(1999)43:1<72::AID-CM8>3.0.CO;2-U.PMID10340705.
^Carey, Phillip G. (1992).Marine Interstitial Ciliates: An Illustrated Key. Chapman and Hall. p. 112.ISBN978-0-412-40610-2.
