. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OD= 0 B t = 0 min OD= 0 t =20-30 min OD= 1/10X t =20-30 min OD= X E ( control, no attractam ) F ( attractant) Figure 1. Schematic representation of the quantitative two-phase assay. Cells starved in a 500-ml Fernbach flask at a concentration of 1- 2 x 105 cells ml'1 at a temperature of 2I°C for 20-40 h are used. OD600 of the cell suspension was measured just before the experiment, using the solution of metnzamide as reference. In this example, OD of the cell suspension equals X (A). One milliliter of the metnzamide solut
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OD= 0 B t = 0 min OD= 0 t =20-30 min OD= 1/10X t =20-30 min OD= X E ( control, no attractam ) F ( attractant) Figure 1. Schematic representation of the quantitative two-phase assay. Cells starved in a 500-ml Fernbach flask at a concentration of 1- 2 x 105 cells ml'1 at a temperature of 2I°C for 20-40 h are used. OD600 of the cell suspension was measured just before the experiment, using the solution of metnzamide as reference. In this example, OD of the cell suspension equals X (A). One milliliter of the metnzamide solution is filled into the microcuvettes and each cuvette is blanked (B). Using a pasteur pipette and a steady fingertip. ml of the cell suspension is carefully layered on top of the melrizamide (C). Immediately after the cells are applied, the optical density of the lower phase should still be zero (D). After 20-30 min, the OD of the lower phase containing 1 mg proteose peptone ml'1 will increase to about X, implying that virtually all cells are now present in the lower phase (F). In the control cuvette, the OD is only slightly increased—to about 1/10 X (E). assays in these experiments contained TRIS at the appro- priate concentration. The mixture of amino acids was prepared in a stock solution composed of 10 mM of each of the amino acids found in a synthetic medium proposed for growth of Tet- rahymena (Rasmussen and Modeweg-Hansen, 1973). These are DL-alanine, L-arginine, L-asparagine. L-gluta- mate, L-glutamine, glycine, L-histidine, L-isoleucine, L- leucine, L-lysine, DL-methionine, DL-phenylalanine, L- proline, DL-serine, DL-threonine. L-tryptophan, and DL- valine. The amino acid mixture was adjusted to pH = by the addition of NaOH. Results In the experiment shown in Figure 3, cells from late exponential growth phase were starved at a concentra- tion of X 105 cells ml ', and assays were performed after 2, 16, 40, and 64 h of starvation using no attractant (c
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
