Uronemella
Uronemella Song & Wilbert (ref. ID; 4523)
- Uronemella filificum (ref. ID; 4523)
Syn; Uronema filificum (ref. ID; 4523)
Synonym
Uronema filificum (ref. ID; 4523)
Descriptions
Cells in vivo about (30-45) um x (20-30) um in size, shape rather stable, broadly oval with ventral side more or less concave, while dorsally considerably convex; cross section circular. Frontal end flat and slightly truncated with large, conspicuous apical plate, which is about half the width of the body. Buccal field about 3/5 of body length with cytostome slightly posterior to equatorial level position. Macronucleus large, rounded to oval, located centrally. Cilia densely arranged; a typical caudal cilium complex at the end of cell. Typical rotatory movement, with a slim thread sticking to debris while slowly rotating around longitudinal axis of body. When disturbed, cells moving quickly, back and forth on the bottom. Somatic ciliature genus-typical, mostly 23 ciliary rows extending occur entire length of body, composed of close-set dikinetids in anterior half of body, but loosely-arranged monokinetids in posterior half. Buccal apparatus similar to that of Uronema. Membranelle 1, consisting of ca. 6-8 basal bodies arranged in one row attached with two basal bodies, well separated from other membranelles; membranelle 2 and 3 short and near to each other, each consisting of 3 rows of basal bodies. Paroral membrane on right of buccal cavity, with zigzag row of basal bodies, extending anteriorly to about middle of membranelle 2. Scutica comprising 2 to 3 pairs of basal bodies. (ref. ID; 4523)
Morphogenesis: Morphogenesis in Uronemella filificum begins with the proliferation of kinetosomes in scutica, which are arranged irregularly in 6-7 pairs. This structure is designed as the primary field of the primordium (PF for short) because it appears first at the very beginning of the stomatogenesis. At the same time, the zig-zag configuration of the paroral membrane begins to split into two rows longitudinally, of which the right one (the outer row) serves as a new primordium, namely, the secondary field (SF). The basal bodies in the kineties also begin to proliferate, thus, the monokinetids formerly in the post part of kineties become di- or tri-kinetids. With a marked proliferation, the secondary field fragmentizes into to portions, the anterior and the posterior one (SFa and SFp for short respectively). SFa possesses a 2-rowed structure, while SFp has one row of basal bodies at the moment. While the kinetosomes of the primary field arrange and migrate posterior, the proliferated SFa moves down extremely to SFp. At this stage, the PF is composed of three parts, the middle one with about 3-4 rows of basal bodies, while the anterior and the posterior one are made up of only three basal bodies each. In migrating posteriorly, SFp experiences a J-shaped configuration with the terminus curving rightward. The anterior part of PF remains at the initial position, while the other two parts of PF migrate posteriorly. Then, the SFa moves posteriorly and rearranges, the SFp develops into two parts and several sparsely arranged basal bodies, and the macronucleus becomes sausage-shaped. The characteristic change in this stage is the enlarged remnant Paroral membrane (PM) which terminates anteriorly at the anterior of M1, while in the opisthe, the SFa enlarges and curves as a long curveted structure. At the next stage, the cell develops into two similar parts, which is referred as proter and opisthe respectively. The posterior kinetosomes of the PM in both proter and opisthe proliferated giving rise to a kinetosomal hook that later differentiates into the scutica, while the three membranelles experience a slight rotation and rearrangement. The final phases of stomatogenesis, just before cytokinesis takes place. The field of kinetosomes that give rise to M1 in both proter and opisthe is now parallel to the longitudinal axis of the cell and is formed by only one row of kinetosomes. The other fields also reorganize and reabsorb their kinetosomes to produce the final membranelles. The three parental membranelles are inherited to the proter. (ref. ID; 4523)