A novel Tetrahymena thermophila sterol C-22 desaturase belongs to the fatty acid hydroxylase/desaturase superfamily.

Sterols in eukaryotic cells play important roles in modulating membrane fluidity and in cell signaling and trafficking. During evolution, a combination of gene losses and acquisitions gave rise to an extraordinary diversity of sterols in different organisms. The sterol C-22 desaturase identified in plants and fungi as a cytochrome P-450 monooxygenase evolved from the first eukaryotic cytochrome P450 and was lost in many lineages.

Genome analysis of sphingolipid metabolism-related genes in Tetrahymena thermophila and identification of a fatty acid 2-hydroxylase involved in the sexual stage of conjugation.

Sphingolipids are bioactive lipids present in all eukaryotes. Tetrahymena thermophila is a ciliate that displays remarkable sphingolipid moieties, that is, the unusual phosphonate-linked headgroup ceramides, present in membranes. To date, no identification has been made in this organism of the functions or related genes implicated in sphingolipid metabolism.

Genome-wide Transcriptional Analysis of Tetrahymena thermophila Response to Exogenous Cholesterol.

The ciliate Tetrahymena thermophila does not require sterols for growth and synthesizes pentacyclic triterpenoid alcohols, mainly tetrahymanol, as sterol surrogates. However, when sterols are present in the environment, T. thermophila efficiently incorporates and modifies them.

Gene identification and functional characterization of a Δ12 fatty acid desaturase in Tetrahymena thermophila and its influence in homeoviscous adaptation to low temperature.

Homeoviscous adaptation in poikilotherms is based in the regulation of the level of desaturation of fatty acids, variation in phospholipids head groups and sterol content in the membrane lipids, in order to maintain the membrane fluidity in response to changes in environmental temperature. Increased proportion of unsaturated fatty acids is thought to be the main response to low-temperature acclimation, which is mostly achieved by fatty acid desaturases. Genome analysis of the ciliate Tetrahymena thermophila and a gene knockout approach has allowed us to identify one Δ12 FAD and to study its activity in the original host and in a yeast heterologous expression system.

Biotechnology in ciliates: an overview.

Since their description and classification in the 19th century, ciliates have played an important role in science, leading to several fundamental discoveries in the areas of cellular and molecular biology. During the last decades, with the emergence of biotechnology, many new developments are also coming to light. In this review, we describe a range of applications in which ciliates have found a niche, ranging from the production of a vast array of proteins, lipids, metabolites, and antigens to their use in toxicity screening, biocontrol, bioremediation, and biotransformation of substrates into more valuable products.