Cell suspensions

After recovery of L-lysine, the residual dl-(49) is epimerized to a mixture of the DL and meso isomers, and the latter is subjected to the same decarboxylation step. This reaction is a part of a microbial process in which glucose is fermented by a lysine auxotroph of E. coli to meso- which accumulates in the medium. Meso-(49) is quantitatively decarboxylated to L-lysine by cell suspensions oi erobacteraerogenes (93). However, L-lysine and some... 

The alternative to batch mode operation is continuous operation. In the continuous mode there is a continuous flow of medium into the fermentor and of product stream out of the fermentor. Continuous bioprocesses often use homogenously mixed whole cell suspensions. However, immobilised cell or enzyme processes generally operate in continuous plug flow reactors, without mixing (see Figure 2.1, packed-bed reactors). 

Fig. 17.2. Sketch of the Dyno Mill KDLT. 1. Cell suspension inlet 2. agitator disks 3. coolant 4. disruptate oudet 5. gap separator 6. motor 7. Coolant.

There is much current interest aimed at the implementation of processes that integrate the upstream and downstream operation for protein recovery.131419 Although adsorption in fluidised beds provides a considerable saving in cost and time over conventional purification techniques, it still deploys a discrete operation with which the desired protein is captured at termination of fermentation or once a cell suspension has been disrupted. The main... 

Leibo, S.P., Farrant, J., Mazur, P., Hanna, M.G., Jr., Smith, L.H. (1970). Effects of freezing on marrow stem cell suspensions Interactions of cooling and warming rates in the presence of PVP, sucrose, or glycerol. Cryobiol. 6, 315-332. 

Animal cell cultures that are initiated from cells removed directly from the animal are called primary cultures (Figure 2). Primary cultures include both explant cultures (i.e., cultures initiated from small pieces of intact tissue), as well as cultures initiated from preparations of individual or dispersed cells (obtained from intact tissue by mechanical or proteolytic dismption). Nerve fiber explant cultures in blood plasma were among the earliest types of tissue cultures (Harrison, 1907). Cells grow out from such tissue explants and form a single layer of cells completely filling the tissue culture vessel surface. Such cell cultures are called confluent monolayers. Confluent monolayers can then be treated with trypsin, so as to remove the individual cells from the culture vessel surface. The resulting cell suspension is then transferred into other culture containers, so that more viable monolayer... 

Figure 4. Neurite outgrowth by LA-N-1 human neuroblastoma cells in culture. LA-N-1 human PNS neuroblastoma cells were grown for five days in N2 medium (as described by Bottenstein and Sato, 1979) on a polylysine and fibronectin-modified surface. The cells were plated in clumps, rather than as a single cell suspension, which enhances neurite extension. Very long processes result, and exhibit varicosities along their length. Most of the cells have migrated from the central clump. (Photo courtesy of Dr. jane Bottenstein.)...

Table I describes several of the fluorescent assays that have been used in our lab to study neutrophil activation. Fluorescein-labeled W-formylhexapeptide (FLPEP) has been used to characterize the ki- netics of ligand binding, dissociation, and internalization at 37°C (7,8). FLPEP is added to a suspension of cells, then receptor-bound and free FLPEP in solution are distinguished by adding antibody to fluorescein. This is a high-affinity antibody which binds free FLPEP within 1 s hut does not bind cell-bound FLPEP. When it binds the FLPEP, it quenches the fluorescein fluorescence. Hence the residual fluorescence after antibody addition represents FLPEP that is bound to the cell. Nonspecific binding is determined in cell suspensions that contain an excess of nonfluorescent peptide.

Figure 9. Increase of intracellular Ca stimulated by various HCH isomers. Cells were labeled with lndo-1 and suspended at 2 X 10 cells/mL buffer at 37°C. The HCH isomers were dissolved in DMSO and added to the cell suspensions such that the final HCH concentration was 260 pff and the final DMSO concentation was 0.25% (v/v). The various isomers are indicated in the plot. The control is DMSO alone. The data are plotted as the ratio of fluorescence at 400 nm (measured on channel A) to that at 490 nm (measured through a Corion 490-nm interference filter on channel B).

The increase in Ca is initiated rapidly and begins to recover after 1 min. The order of potency correlates fairly well with the solubilities of these compounds in organic solvents (37) and their abilities to accumulate in phospholipid vesicles (38), i.e., 6>y>a>p, but not with their insecticidal activity (y 6>a p 39). At these concentrations, crystals of p-, a-, and y-HCH were evident in the cell suspensions when we made simultaneous measurements of the right-angle light scatter, indicating that the order of aqueous solubilities is 6>y>a>p. However, stimulation by 6-HCH at concentrations below its aqueous solubility limit shows a typical dose dependency of the response (Figure 10). 

In order to derive a quantitative relation between emission Intensity as measured by EMI and actual metal content, cell samples were subjected to graphite furnace atomic absorption (GFAA) analysis (14). Atomic absorption experiments were performed both on cells which had been stained with a fluorescent reagent and on cells not exposed to a lumlnophore. After EMI analysis, 50 fiL of cell suspension were withdrawn from the 0.30 mL of sample used for EMI and were digested In 150 iiL of concentrated HNO3 for 90 minutes at 85° . These solutions were then diluted to 1/10 of their concentration with deionized water, and the 150 liL of these diluted... 

Cell suspensions which were exposed to 1.0 ppm zinc were combined, and to this matrix known amounts of Zn were added, to allow measurement of the amount of zinc accumulated by the cells via GFAA. In related work, cells treated with known concentrations of zinc solutions were systematically combined and thereby "diluted" with cells not exposed to zinc, to determine If GFAA and EMI analyses yield confirmatory results. 

Cabrera J. C. Messiaen J. Cambier P. Van Cutsem P. (2006) Sise, acetylation and concentration of chitooligosaccharides eHcitors determine the switch from defence involving PAL activation to cell death and water peroxide production in Arabidopsis cell suspensions / / Physiologia plantarum. V. 127. P. 44-56. 

Reaney, M.J.T. Gusta, L.V. (1987). Factors influencing the induction of freezing tolerance by abscisic acid in cell suspension cultures of Bromus inermis Leyss and Medicago sativa L. Plant Physiology, 83, 423-7. 

Fig. 11. Capillary data showing an increase in the release of intracellular calcium content (340/380 ratio) as s increases. Data refer to experiments in which the cell suspension was circulated through a fine bore capillary for 15 min. Error bars represent the 8.0% standard deviation [87]...

Effects of Hydrodynamic and Interfacial Forces on Plant Cell Suspension Systems... 

Keywords. Plant cell suspensions. Hydrodynamic shear. Energy dissipation. Aeration, Oxidative burst... 

Plant cell suspensions offer the potential to produce valuable phytochemicals, traditionally extracted from the naturally grown whole plant, under controlled and reproducible conditions. To date, commercial processes involving these systems have been limited to just a handful of applications, including the much-cited shikonin [1] and ginseng [2,3]. 

The susceptibility of biological systems, including procaryotic and eucaryo-tic cultures and enzyme solutions, to the forces prevailing under normal processing conditions has been extensively studied and is the subject of comprehensive reviews [12-16], including other chapters in this volume. Downstream processing operations, as well as routine pumping, will expose cell suspensions... 

The purpose of this chapter is to review relevant work in the area, including an evaluation of methods employed for shear sensitivity studies, comparison of bases for data analysis and an outline of current knowledge of the interface between the hydrodynamic environment and the plant cells themselves. Coverage is limited to cell suspension cultures and does not extend to other tissue or organ systems. 

For plant cell suspensions cultivated in shake flasks, Huang et al. [45] used the energy dissipation rate as a correlating parameter for system response. Specific power input was calculated using the empirical correlation proposed by Sumino et al. [46] and subsequently employed in other applications [47,48] ... 

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