On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes

Abstract

In the ciliate, Tetrahymena pyriformis, the population of cell organelles shows variation during the culture cycle and when the cells are subjected to various treatments. New cell constituents may appear and the fine structure of mitochondria and peroxisomes may change. Such dynamic structural changes are described and reviewed in relation to physiological and biochemical studies on Tetrahymena. The cell organelles discussed are about I tam in diameter or smaller~ reference is also made to the nuc[eotar organization which is the most sensitive indicator of the physiologica~ state of the ceils. The presumed distribution of the various cell organelles in subcellular fractions of Tetrahymena is mentioned, since dependent on the pretreatment of the cells, especially the mitochondrial and peroxisomal fractions may be contaminated to varying degrees with other cell organelles~The purpose of the review is to demonstrate that a correlation exists between the structure and function of cell organelles, especially mitochondria and peroxisomes, and that the overall fine structure of a cell reflects its physiological state.

Intracellular bioaccumulation of the rare earth element Gadolinium in ciliate cells resulting in biogenic particle formation and excretion

“…We want to emphasize that our results clearly show that a distinction must be made between particles containing metals (as in our case Gd) and having a size of about 3 µm on the one hand and smaller granules with a size of about 0.6 µm on the other hand. The small granules reported in this work occurring during the stationary growth phase, under unfavourable growth conditions or after further CaCl 2 treatment are consistent with prior literature data on granules that were assumed to play a role in ion regulation and storage, especially that of Ca 2+ ions 37,61 . During metal treatment of the cells, heavy metals could be deposited in the granules along with, indicating a role in detoxification as well 22,[35][36][37]39,60 .…”

Extrusomes in Ciliates: Diversification, Distribution, and Phylogenetic Implications

“…A rosette of 15‐nm particles forms within the plasma membrane when the mucocysts reaches a critical distance from it (Satir, Schooley, and Satir 1973). Mucocysts are very numerous: ∼ 1,000 in T. pyriformis according to Nilsson (1981); 4,500 according to other authors (Frankel 1999). They are arrayed in longitudinal files, half of them along the ciliary rows, and the other half along “secondary meridians” situated halfway between the ciliary rows at the alveolar junction (Allen 1967; Satir and Wissig 1982).…”

On starvation-induced autophagy in Teraahymena

“…tural changes in the cells. Mitochondria and peroxisomes change into their "dense" type (26,27,28), the nucleoli form aggregates, and glycogen particles, lipid droplets, and dense granules appear (27). Furthermore, laminated membranous material is seen below the cell surface in alveolar sacs, in the cytoplasm near mitochondria, and within rough endoplasmic reticulum cisternae.…”

“…In Tetrahymena autophagosomes are not seen in cells from rapidly proliferating cultures but they appear whenever growth is inhibited (27,28). The highest frequency of autophagy occurs when cells from rapidly proliferating cultures are exposed abruptly to starvation (27).…”