Protozoans Tetrahymena pyriformis

Toyopearl HW-50S resin has been used to help isolate the ubiquitin-histone conjugate mH2A from the unicellular ciliated protozoan Tetrahymena pyriformis. Figure 4.49 shows the separation of mH2A from the histone, H2A. The sole difference between these two components is a small polypeptide, ubiquitin (approximately 8500 Da). The mH2A fraction was then further purified by HPLC on a Tosoh ODS-silica column (52). One of the many benefits... 

Toropov AA, Benfenati E (2004) QSAR modelling of aldehyde toxicity against a protozoan, Tetrahymena pyriformis by optimization of correlation weights of nearest neighboring codes. J. Mol. Struct. (Theochem) 679 225-228. 

Bogaerts, P. Bohatier, J. Bonnemoy, E. Use of the ciliated protozoan Tetrahymena pyriformis for the assessment of the toxicity and quantitative structure-activity relationships of xenobiotics comparison with the microtox test. Ecotox. Environ. Safe. 2001, 49, 293-301. 

It is interesting to note that the protozoan, Tetrahymena pyriformis, lacks the capacity of sterol biosynthesis, but has the ability to dealkylate phytosterols [173]. 

Another interesting membrane effect of chlorpromazine (and other phenothiazines), which may connect its action with phosphatidylcholine, is that described by Guttman and Friedman (1963). ITiey found that 3 X 10 M chlorpromazine immobilized the protozoan Tetrahymena pyriformis in 15 minutes, and that this was due to an increased permeability of the cell membrane which finally ruptured. Antimobility activity paralleled clinical effectiveness for a variety of phenothiazines. Membrane damage could, moreover, be prevented by the presence of phosphatidylcholine, an effect not due to the binding of chlorpromazine in the medium. Unfortunately, phospholipids other than phosphatidylcholine were not tested and it would be of interest to know if the cell membrane of T. pyriformis is rich in this phospholipid. 

When the protozoan Tetrahymena pyriformis is grown in the presence of... 

The properties of a soluble enzyme system from plants which catalyses cyclization of squalene 2(3),22(23)-diepoxide into oc-onocerin (28) have been reported. The enzyme requires both substrate epioxide groups for recognition and cyclization of the substrate. Additional inhibitors of squalene 2,3-oxide cyclase have been described, and a comparison of the effects of numerous hypocholesterolaemic agents on squalene metabolism in rat liver and the protozoan Tetrahymena pyriformis has been reported. ... 

Metabolism of Sterols. It is interesting that a heat-stable sterol carrier protein (SCP) has been detected in the protozoan Tetrahymena pyriformis. This protozoan-SCP (P-SCP) was required, in addition to oxygen and pyridine nucleotides, for conversion of cholesterol into cholesta-5,7,22-trien-3p-ol by the protozoan microsomal enzymes (A - and A -dehydrogenase). It is interresting that both protozoan-SCP and liver-SCP are interchangeable in cholesterol biosynthesis by liver enzymes and the oxidation of cholesterol to the triene by protozoan enzymes. The effect of numerous hypocholesteraemic compounds on the cyclization of squalene to the pentacyclic triterpenoid tetrahymanol has also been studied in Tetrahymena. ... 

Aptula et al. used multiple linear regression to investigate the toxicity of 200 phenols to the ciliated protozoan Tetrahymena pyriformis Using their MLR model, they then predicted the toxicity of another 50 phenols. Here we present a comparative study for the entire set of 250 phenols, using multiple linear regression, artificial neural networks, and SVM regression methods. Before computing the SVM model, the input vectors were scaled to zero mean and unit variance. The prediction power of the QSAR models was tested with complete cross-validation leave-5%-out (L5%0), leave-10%-out (L10%O), leave-20%-out (L20%O), and leave-25%-out (L25%0). The capacity parameter C was optimized for each SVM model. 

Seaman, G. R. (1960). Large scale isolation of kinetosomes from the ciliated protozoan Tetrahymena pyriformis. Exptl. Cell Res. 21, 292. 

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