Proposed function of the accumulation of plasma membrane-type Ca2+-ATPase mRNA in resting cysts of the ciliate Sterkiella histriomuscorum.

From an mRNA differential-display analysis of the encystment-excystment cycle of the ciliate Sterkiella histriomuscorum, we have isolated an expressed sequence tag encoding a plasma membrane-type Ca2+-ATPase (PMCA). PMCAs are located either in the plasma membranes or in the membranes of intracellular organelles, and their function is to pump calcium either out of the cell or into the intracellular calcium stores, respectively. The S.

Localization of centrins in the hypotrich ciliate Paraurostyla weissei.

Centrins are ubiquitous cytoskeletal proteins that are generally associated with the centrosome and form large cytoskeletal networks in protists. To obtain more data on the respective role of different centrin proteins, we studied their distribution and behavior in one ciliate species, Paraurostyla weissei, using specific antibodies. In this species, only two major proteins of 21 and 24 kDa corresponding to centrins, were identified by 1D and 2D electrophoresis.

Cysteine proteases and cell differentiation: excystment of the ciliated protist Sterkiella histriomuscorum.

The process of excystment of Sterkiella histriomuscorum (Ciliophora, Oxytrichidae) leads in a few hours, through a massive influx of water and the resorption of the cyst wall, from an undifferentiated resting cyst to a highly differentiated and dividing vegetative cell. While studying the nature of the genes involved in this process, we isolated three different cysteine proteases genes, namely, a cathepsin B gene, a cathepsin L-like gene, and a calpain-like gene. Excystation was selectively inhibited at a precise differentiating stage by cysteine proteases inhibitors, suggesting that these proteins are specifically required during the excystment process.

Structural inheritance in Paramecium: ultrastructural evidence for basal body and associated rootlets polarity transmission through binary fission.

One main difference between basal bodies and centrioles resides in the expression of their polarity: centrioles display a structural nine-fold radial symmetry, whereas basal bodies express a circumferential polarity, thanks to their asymmetric set of rootlets. The origin of this polarity during organelle duplication still remains under debate: is it intrinsic to the nine-fold structure itself (i.e.

Plateins: a novel family of signal peptide-containing articulins in euplotid ciliates.

In euplotid ciliates, the cortex is reinforced by alveolar plates--proteinaceous scales located within the membranous alveolar sacs, forming a monolayer just below the plasma membrane. This system appears to play a cytoskeletal role analogous to that provided by the fibrous epiplasm found beneath the cortical alveoli in other ciliates. In Euplotes aediculatus, the major alveolar plate proteins (termed alpha-, beta-, and gamma-plateins) have been identified.