Reproduction and life history

Trimastix cells reproduce asexually by binary fission, with mitotic division of the nucleus.

During late interphase, new basal bodies form in the kinetid. At the onset of prophase, the old microtubular roots become separated from the kinetid and eventually disappear. The eight basal bodies separate semiconservatively (two parental ones and two new ones in each set). Flagella remain attached to the parental basal bodies throughout mitosis. The basal bodies migrate to opposite ends of the cell and become the focus for the mitotic spindle poles.

The mitotic spindle consists of two cones of microtubules, one from the vicinity of each kinetid. The microtubules of the cones extend to the chromosomes; no microtubules, it appears, extend from spindle pole to spindle pole (in other words, there is no "interzonal spindle"). The nuclear envelope is not visible at metaphase (the spindle is "open"), nor is the nucleolus visible. During anaphase, chromosomes move to the spindle poles. As there does not seem to be a lengthening of the distance between the poles, chromosome movement seems to depend on a shortening of the chromosome-to-pole microtubules.

New microtubular roots, and new flagella on the younger basal bodies, begin to form during late prophase and continue to form during the rest of cell division, so that flagella and the interphase cytoskeleton are fully formed by the completion of cytokinesis (cell separation).

In terms of the architecture of the mitotic spindle, and the sequence of mitotic events, Trimastix has more in common with both the jakobid flagellates and the retortamonads than with any other protist group.

Cysts form, as far as is known, from single trophic cells.

No sexual reproduction has been observed.

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