Treatment in Suspension

Treatment in suspension has the advantage that cells are exposed to a well-defined concentration of a given agent for a defined length of time. Moreover, using buffered solution of an agent allows one to control the j H during the period of treatment. 

The biological and the chemical time factors need not be very severe as long as one is interested in the genetic activity v.s. nonactivity at a qualitative level. For quantitative considerations, however, these factors have to be taken into account. 

Very critical is the choice of j H. Most relevant is the pH range around neutrality. Some genetically active agents, such as nitrious acid, show a sharp response to pH. Other mutagens, however, show a clear pH dependence as well.  

The appropriate choice of the cell-cycle stage is very important for those chemicals which might be mutagenic, not because of their reactivity with DNA, but because of their incorporation as base analogues or, as in the case of 5-fluorodeoxyuridine, their interference with specific reactions involved in DNA replication. 

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Subsequent filtration yields the spent acid filtrate and a cake of aqueous titanium oxide. Thorough washing of the cake, calcination, grinding, surface treatment in suspension, filtration, drying, and micronizing finally lead to the titanium dioxide pigment product. These process steps result in some slightly acidic effluents. 

Hatanaka, R. Sugawara, Y. (2010). Development of Desiccation Tolerance and Vitrification by Preculture Treatment in Suspension-Cultured Cells of the Liverwort Marchantia polymorpha. Planta, Vol. 231, No. 4, (March 2010), pp. 965-976, ISSN 0032-0935Heimburg, T. (2010). Lipid Ion Charmels. Biophysical Chemistry, Vol. 150, No. 1-3, (August 2010), pp. 2-22, ISSN 21530378... 

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