Tetrahymena

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... 

FIGURE 4.49 Isolation of a complex protein conjugate on Toyopearl HW-50S. Column 22 mm X 83 cm. Sample Fraction from crude Tetrahymena H2A containing the ubiquitin-histone conjugate uH2A. Elution 10 nM HCI. Flow rate 0.1 ml/min. Detection UV at 230 nm. 

FIGURE 14.23 RNA splicing in TetraAjimejta rRNA matnradon (a) the gnanosine-mediated reaction involved in the antocatalytic excision of the Tetrahymena rRNA intron, and (b) the overall splicing process. The cyclized intron is formed via nncleophilic attack of the 3 -OH on the phosphodiester bond that is 15 nncleotides from the 5 -GA end of the spliced-ont intron. Cyclization frees a linear 15-mer with a 5 -GA end. 

Tetrahymena thermophila transforms pentachloronitrobenzene to the corresponding aniline and pentachlorothioanisole (Figure 2.24) (Murphy et al. 1982). 

Drotar A-M, LR Fall, EA Mishalanie, JE Tavernier, R Eall (1987) Enzymatic methylation of sulfide, selenide, and organic thiols by Tetrahymena thermophila. Appl Environ Microbiol 53 2111-2118. 

The degradation of 11,12-methyleneoctadecanoate is carried out in Tetrahymena pyri-formis by a modified p-oxidation pathway with the formation of propionate and acetate (Figure 7.34a) (Tipton and Al-Shather 1974). 

Tipton CL, NM Al-Shathir (1974) The metabolism of cyclopropane fatty acids by Tetrahymena pyriformis. J Biol Chem 249 886-889. 

TEST allows for estimates of the value for several toxicity endpoints [29] 96 h Fathead minnow LC50, 48 h Daphnia magna LC50, 48 h Tetrahymena pyriformis IGC50, Oral rat LD50, bioaccumulation factor, developmental toxicity, and Ames mutagenicity. TEST also estimates several physical properties... 

All four scientists whose work led to modification of the dogmas received the Nobel Prize. Thomas Cech (1987) was the first to observe enzyme-like reactions taking place at the same RNA strand, in ribosomal RNA (rRNA) from the proto-zoon Tetrahymena thermophila. The RNA produced, which is completely viable, is formed in a process in which certain sections (introns) of the primary copy (the transcription of DNA to mRNA) are cut out, the two remaining ends of the exon then being rejoined (spliced). 

Cech s group was the first to have success in this direction (Piccirilli, 1992). Using a genetically modified Tetrahymena ribozyme, they were able to hydrolyse an ester bond between the amino acid A-formylmethionine and the corresponding tRNAf Met. The reaction was, however, very slow, only about 5 to 15 times faster than the uncatalysed reaction. The authors ventured to suggest that these ribozymes could have functioned as the first aminoacyl tRNA synthetases. 

Values of molecular weight (uncorrected for dissymmetry) have been obtained by Harrap and Manners238 from light-scattering investigations, as follows rabbit liver, 6.8 X 106 rabbit muscle, 2.8 X 109 cat liver, 10.0 X 109 fetal sheep liver, 14.8 X 106 Tetrahymena pyriformis, 9.8 X 106 and Ascaris lumbricoides, 8.8 X 106. 

Boisson, F., M. Gnassia-Barelli, and M. Romeo. 1995. Toxicity and accumulation of selenite and selenate in the unicellular marine algae Cricosphaera elongata. Arch. Environ. Contamin. Toxicol. 28 497-493. Bovee, E.C. and T.L. O Brien. 1982. Some effects of selenium, vanadium and zirconium on the swimming rate of Tetrahymena pyriformis a bioassay study. Univ. Kans. Sci. Bull. 52 (4) 39 44. 

Horiguchi, M. and Rosenberg, H., Phosphonopyruvic acid a probable precursor of phosphonic acids in cell-free preparations of Tetrahymena, Biochim. Biophys. Acta, 404, 333, 1975. 

Tetrahymena pyriformis utilizes nicotinic acid or nicotinamide when they are added in the same concentration, the increment of growth is less than that predicted from the algebraic sums of the individual increments (Table 5). 

We have developed a direct assay for vitamin Be in blood, serum, urine, cerebrospinal fluid, and tissue, based on the ciliate, Tetrahymena pyriformvs. The techniques are essentially those described for nicotinic acid (see Section 4.1), except that vitamin Be is omitted from the basal medium both nicotinic acid and its amide are added each at 0.1 mg/100 ml of basal medium. The method for blood, serum, urine, cerebrospinal fluid, and tissues is given below. 

Fig. 4. Growth of Tetrahymena pyriformis with members of the vitamin Be group.

Endocytosis of particulate material by Tetrahymena increases growth rate from dissolved nutrients by seven to eight fold [78]. 

Tetrahymena mutants lacking functional phagocytosis require high levels of iron and copper supplements [81]. 

Rasmussen, L. and Kludt, T. A. (1970). Particulate material as a prerequisite for rapid cell multiplication in Tetrahymena culture, Exp. Cell Res., 59, 457-463. 

Nilsson, J. R. (1979). Intracellular distribution of lead in Tetrahymena during continuous exposure to the metal, J. Cell ScL, 39, 383-396. 

Orias, E. and Rasmussen, L. (1976). Dual capacity for nutrient uptake in Tetrahymena. IV Growth without food vacuoles and its implications, Exp. Cell Res., 102, 127-137. 

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