The Contractile Vacuole and Related Structures in Tetrahymena pyriformis*

Abstract

SYNOPSIS. The nephridial system of T. pyriformis consists of a contractile vacuole with its two pores and an elaborate network of tubules. Both the vacuole and its tubules constitute a continuous system of single membranes of approximately 70 Å in thickness. Tubular fibrils of about 250 Å extend from the pore wall to the vacuole membrane and appear to function in dilating the pore prior to systole. The nephridial tubules arise directly from the wall of the vacuole and are continuous with it throughout the vacuolar cycle. The tubules appear to be contiguous with the granular endoplasmic reticulum. A typical Golgi complex was not found. Some speculation about the interrelation of these structures as regards function is offered.

The Role of the Contractile Vacuole in the Osmoregulation of Tetrahymena pyriformis*

“…T o this observer, using phase contrast optics, the vacuole always appears spherical and it has a circular equatorial section even when systole is just starting. The vacuole may collapse to a nonspherical shape during late systole when it is very small, but this was not seen in visual (real-time) observations, Such a nonspherical, very small vacuole, however, is consistent with electronmicroscopic observations (8). In conclusion, we must agree with Dunham & Stoner ( 7 ) that some intrinsic clock triggers systole.…”

“…For Tetrahymena, the relation of systolic duration to the level of cell activity and to the duration and extent of vacuolar filling may be explained as follows. There is some evidence for a direct dependence of vacuolar emptying upon mitochondria1 oxidative-phosphorylation and there is a close spatial association of mitochondria with the vacuolar pore site (8). In addition, the systolic phase of the vacuolar cycle is specifically sensitive to inhibitors and decouplers such as cyanide (4, 12), Janus Green B, and Tetrazolium Blue.…”

“…In addition, the systolic phase of the vacuolar cycle is specifically sensitive to inhibitors and decouplers such as cyanide (4, 12), Janus Green B, and Tetrazolium Blue. The insensitivity of the filling phase to these inhibitors (12) and the lack of mitochondria around the vacuolar membrane of Tetrahymena (8) further suggest a relative independence of vacuolar diastole and systole. Any inhibition of the triggering of systole caused by a possible lowering of the metabolic energy level would lead to a concomitant lengthening of the systolic repetition period.…”

Effect of drugs affecting microtubular assembly on microtubules, phospholipid synthesis and physiological indices (signalling, growth, motility and phagocytosis) inTetrahymena pyriformis

“…Longitudinal microtubule bands are located more external and to the right of each row of ciliary units. In addition to these above-mentioned structures, microtubules are present in micronuclei of T. thermophila 3 at the cytoproct (circular and radial microtubules) 4 and at the oral apparatus (three membranelles, undulating membrane, oral-rib microtubules underlying a 'ribbed wall' on the right side of the oral apparatus, and a bundle of microtubules together making up a 'deep fibre'). 5 The use of drugs as chemical probes to alter microtubule assembly dynamics sensitively in a well-characterized molecular manner can help elucidate the role of dynamic microtubules in specifying or regulating cell function.…”

CONTRACTION OF ISOLATED CONTRACTILE VACUOLES FROM AMOEBA PROTEUS

“…An early demonstration of birefringence of the wall of the contractile vacuole of Amoeba verrucosa is perhaps relevant (23) . Fibrils are associated with the contractile vacuoles of several ciliates (7,25), but there is no reason that contractile vacuoles of ciliates and amoebae, let alone all amoebae, should share a common mechanism for systole . Further studies are necessary for clear evidence on the structural basis for contraction of the contractile vacuole in amoebae .…”