Development of the Ciliary Pattern of the Oral Apparatus of Tetrahymena thermophila¹

Abstract

The sequence of formation and ciliation of basal bodies and the subsequent organization of compound ciliary structures of the oral apparatus of Tetrahymena thermophila was reanalyzed with the aid of scanning electron microscopy of cells in which the epiplasmic layer was exposed, as well as by light microscopy of protargol-impregnated specimens. This combination of methods allowed the delineation of numerous steps in the patterning of the oral ciliature, some of which have received little or no previous attention. Highlights include: the initial formation of "strings" of nonciliated new basal bodies in juxtaposition to relatively few basal bodies of the stomatogenic kinety; generation of basal body pairs, roughly oriented along the anteroposterior axis of the cell, that later align side-by-side to assemble promembranelles; condensation and reorientation of promembranelles simultaneous with addition of a third row of basal bodies anterior to the original two rows; production of a very short fourth row of basal bodies at the anterior right end of each developing mernbranelle; generation of the outer basal body row of the undulating membrane (UM) after alignment of the inner row, with transient ciliation of the inner row preceding permanent ciliation of the outer row; limited basal body resorption at the ends of membranelles; and sculpturing of the right ends of membranelles by a movement of basal bodies associated with formation of the ribbed wall adjacent to the UM. In the old anterior oral apparatus a repetition of the processes of generation of a new outer UM row and sculpturing of right ends of membranelles takes place in synchrony with the corresponding events in the oral primordium, following prior shedding of the old outer UM row and loss of the sculptured pattern in association with temporary regression of the ribbed wall microtubules. Oral development is complex, with different processes involved in the assembly of the mernbranelles and the UM, and with

What Do Genic Mutations Tell Us about the Structural Patterning of a Complex Single-Celled Organism?

“…In the other half of the mpG-1 cells, which expressed two membranelles, both membranelles were almost invariably abnormal. The second membranelle had an M-2/3 pattern very sim- (8). The dependence of the membranelle pattern signature on the number of membranelles in mpG-1 cells is clearly more consistent with the "unified-membranellar-field" model than with the "membranellar-blueprint" alternative.…”

“…Thus, in an OA with five membranelles, the first membranelle had an "M-1" signature, the third had an "M-2" signature, and the fifth had an "M-3" signature. The second and fourth membranelles had intermediate structural signatures ("M-1/2" and "M-2/3," respectively), such as are not seen in normal three-membranelle OAs (8). This implies the existence of a spatially graded field, perhaps a field of forces responsible for displacing basal bodies as the oral cavity is sculptured late during oral development (see Fig.…”

“…The UM, on the right of the OA, consists of a single row of cilia (whose bases are seen in Fig. 8A) underlain by a double row of basal bodies (8,111,159). The three membranelles, on the left of the OA, each consist of three rows of ciliated basal bodies modified into a "sculptured" pattern generated during late stages of oral development (see Fig.…”

“…The three membranelles, on the left of the OA, each consist of three rows of ciliated basal bodies modified into a "sculptured" pattern generated during late stages of oral development (see Fig. 8A) (8,159).…”

Determination of cellular rate distributions in microbial cell populations: Feeding rates of ciliated protozoa

“…The working form of Eq. (2) for a gamma density function then becomes i j ( 1 + ke;) i = 0 , 1 , 2 , ... (3) where pc and t3c are the mean and the coefficient of variation of the distribution of the maximum clearance rates. When the clearance rate is not distributed-i.e., fc(c) = S(c -pc), where 6(c) is the Dirac delta function, or equivalently Bc = 0-both Eq.…”