Supply cultural change

Nadeau I, Sabatie J, Koehl M, et al. (2000). Human 293 cell metabolism in low glutamine-supplied culture Interpretation of metabolic changes through metabolic flux analysis. Metabol. Engineer. 2 277-292. 

This chapter describes foundation elements for supply chain change. Foundation elements are the basic building blocks needed if change is to occur. They are cultural rather than structural. Their existence will depend on the values, beliefs, and management philosophy of the organization s leaders, not on formal rules or procedures. We describe four in this chapter ... 

The most important type of mixed solution is a buffer, a solution in which the pH resists change when small amounts of strong acids or bases are added. Buffers are used to calibrate pH meters, to culture bacteria, and to control the pH of solutions in which chemical reactions are taking place. They are also administered intravenously to hospital patients. Human blood plasma is buffered to pH = 7.4 the ocean is buffered to about pH = 8.4 by a complex buffering process that depends on the presence of hydrogen carbonates and silicates. A buffer consists of an aqueous solution of a weak acid and its conjugate base supplied as a salt, or a weak base and its conjugate acid supplied as a salt. Examples are a solution of acetic acid and sodium acetate and a solution of ammonia and ammonium chloride. 

Over a long time period it may well not be possible to duplicate library cell culture conditions. What happens when the lot of media used in the final culture step prior to pyrolysis has been consumed Can culture media suppliers assure nutritional identity between batches Media types for growth of fastidious strains invariably include natural products such as brewer s yeast, tryptic soy, serum, egg, chocolate, and/or sheep blood. Trace components in natural products cannot be controlled to assure an infinite, invariable supply. The microtiter plate wells used here do not hold much media. Even so, the day will come when all media supplies are consumed and a change in batch is unavoidable. When that happens, if there were no effective way to compensate spectra for the resulting distortions, it would be necessary to re-culture and re-analyze replicates for every strain in the reference library. Until recently the potential for obsolescence was a major disincentive for developing PyMS spectral libraries of bacteria. Why this is no longer an insurmountable problem is discussed in the next section. 

He Y, Liao H, Yan X (2003) Localized supply of phosphorus induces root morphological and architectural changes of rice in split and stratified soil cultures. Plant Soil 248 247-256. doi http //dx.doi.org/10.1023/A 1022351203545... 

Suspension systems can be operated in different modes batch, fed-batch, chemostat, and perfusion (Fig. 1). These operation modes differ basically in the way nutrient supply and metabolite removal are accomplished, which in turn determines cell concentration, product titer and volumetric productivity that can be achieved [8]. The intrinsic limitation of batch processes, where cells are exposed to a constantly changing environment, limits full expression of growth and metabolic potentials. This aspect is partially overcome in fed-batch cultures, where a special feeding strategy prolonges the culture and allows an increase in cell concentration to be achieved. In perfusion and chemostat processes nutrients are continuously fed to the bioreactor, while the same amount of spent medium is withdrawn. However, in perfusion cultures the cells are retained within the bioreactor, as opposed to continuous-flow culture (chemostat), which washes cells out with the withdrawn medium [9]. 

The importance of zinc for a normal functioning of the Cu-Zn-SOD was shown in Lemna gibba. In zinc-deficient culture media the activity of Cu-Zn-SOD was strongly inhibited whereas in copper-deficient media little change was found in the enzyme activity (Vaughan et al., 1982). In extracts of zinc-deficient plants, restoration of enzyme activity was possible by supplying zinc to the enzyme assay medium. 

Nahapetian AT, Thomas JN, Thilly WG (1986), Optimization of environment for high density VERO cell culture effect of dissolved oxygen and nutrient supply on cell growth and changes in metabolites, J. Cell Sci. 81 65-103. 

Fig. 3A,B. Changes in RubisCO activity and Chi content during acclimation cultures of photomixotrophic pak-bung hairy roots to photoautotrophy. Each culture was carried out using the conical flasks illuminated at I= 11 W nr2 and shaken at 100 rpm with A plain air (0.03 % C02) supply B 3.0% C02-enriched air supply...

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