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This review analyzes the advantages and disadvantages of using eukaryotic microorganisms to design whole-cell biosensors (WCBs) for monitoring environmental heavy metal pollution in soil or aquatic habitats. Basic considerations for designing a eukaryotic WCB are also shown. A comparative analysis of the promoter genes used to design WCBs is carried out,(More)
BACKGROUND Metallothioneins are ubiquitous small, cysteine-rich, multifunctional proteins which can bind heavy metals. METHODOLOGY/PRINCIPAL FINDINGS We report the results of phylogenetic and gene expression analyses that include two new Tetrahymena thermophila metallothionein genes (MTT3 and MTT5). Sequence alignments of all known Tetrahymena(More)
Laboratory toxicity tests, using ciliated protozoa, are scarce and they have been carried out usually with freshwater species. In this study, we have analysed the acute cytotoxicity of Cd, Zn and Cu in five different strains of very common soil ciliate species (Colpoda steinii, Colpoda inflata and Cyrtolophosis elongata), which were isolated from very(More)
In the present study, we have assessed by flow cytometry, the cytotoxicity of the heavy metals Cd, Zn and Cu on populations of the ciliated protozoan Tetrahymena thermophila. The obtained LC(50) for these metals was estimated as 0.195mgCdl(-1), 3.58mgZnl(-1) and 0.47mgCul(-1), respectively. As a result, the toxicity rank for this eukaryotic microorganism is(More)
Reactive oxygen species (ROS) induction by exposure to heavy metals (Cd, Cu or Zn) in diverse free-living ciliated protozoa (Tetrahymena sp. and three strains of Colpoda steinii, isolated from freshwater and soils with different level of metal pollution) has been evaluated. Using specific fluorophores, such as 2',7'-dichlorofluorescein diacetate,(More)
Much experimental evidence on the role of DNA methylation in gene expression has been reported. Here we review reports on DNA methylation in ciliated protozoa, emphasizing its implications in cell differentiation processes. Both types of methylated bases (adenine and cytosine) can be found in macronuclear DNA. The division cycle and conjugation have been(More)
This review outlines the main features of ciliate resting-cyst formation or encystment. It represents a strategy against several environmental stresses (such as starvation), which involves a highly gene-regulated cell differentiation process and originates a more resistant, differentiated form or resting cyst. This process is mainly characterized by drastic(More)
In this work we propose a generalized model to explain encystment (cryptobiosis) in ciliates. The model is elaborated from both structural and physiological studies previously reported, and some hypothetical considerations. The main features of this model are the following: (a) starvation is considered as the most important inducer of ciliate encystment,(More)
This article represents an updated review of ciliate metallothioneins (Tetrahymena species) including a comparative analysis with regard to well-known metallothioneins (MTs) from other organisms and discussion of their exclusive features. It opens with an introduction to ciliates, summarizing the main characteristics of these eukaryotic microorganisms and(More)
We report the cloning and characterization of two new metallothionein (MT) genes (TrosMTT1 and TrosMTT2), isolated as cDNAs, from the ciliated protozoa Tetrahymena rostrata. The TrosMTT1 inferred protein has been identified as a CdMT and included into the 7a subfamily of Tetrahymena MTs, while TrosMTT2 has been identified as a CuMT (including it into 7b(More)