Reproduction and life history

Reclinomonas cells reproduce asexually by binary division. No sexual reproduction has been observed.

The first sign of imminent cell division is the formation of two new basal bodies in the vicinity of the old ones.

Just prior to prophase, the basal bodies split into two pairs, which then migrate to opposite ends of the cell. Each pair consists of one "old" and one "new" basal body. The "old" basal body in each pair will become basal body 1 (eldest) in the progeny cells. Flagella remain attached to the old basal bodies, and new flagella form on the new basal bodies. Flagella remain attached throughout division. The microtubular roots of the parent cell are severed from the separating basal body pairs near their proximal ends (the ends nearest the basal bodies). The roots then progressively depolymerize posteriorly.

At prophase, the basal bodies are located at the spindle poles. Each basal body pair is the focus for a cone of microtubules that extends toward and envelops the nucleus. Also, at each basal body pair, new microtubular roots have begun to form. The nuclear envelope initially remains intact, but later dissipates, at which time the microtubules enter the nucleus and become associated with chromosomes. Chromosome condensation is evident at prophase. The nucleolus remains intact.

At metaphase, there are two conical "half-spindles" focused on the basal body complexes and terminating at the chromosomal plate. Chromosomes are small, irregularly shaped and difficult to count. The number appears to be in th twenties or thirties. The nucleolus is persistent.

Chromosome movement at anaphase appears to be due mostly to the separation of the spindle poles. There do not appear to be any microtubules that extend from one spindle pole to the other (that is, there is no "interzonal spindle"), and shortening of the microtubules in the half spindles is minimal until late anaphase and telophase.

At telophase, nuclei reform, chromosomes decondense, and spindle microtubules disappear. A cleavage furrow is initiated between the basal body pairs and progresses posteriorly until the cells are separated. The reforming microtubular roots are visible just behind the leading edge of the cleavage furrow.

The progeny cell that receives the parent cell's anterior flagellum (basal body 2) also receives a large vesicle containing lorica scales. This cell becomes the zoospore and swims away. After an hour or so, this swimming cell settles, secreting its lorica, and its elder flagellum becomes associated with the ventral groove and develops a vane ... that is, the anterior flagellum of the parent cell becomes the posterior flagellum of the progeny cell.

The progeny cell that receives the parent cell's posterior flagellum remains in the parent lorica.

Cysts form, as far as is known, from single trophic cells. Their prevalence and role in nature is unknown. In culture, they remain viable for several months, germinating upon a change in culture medium upon the appearance of fresh food bacteria.

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