Chapter 6: Membranes - Endnotes


  1. Modified from Giese, A.C. 1964. Laboratory Manual in Cell Physiology Revised ed., p 67-68. Boxwood Press, Pittsburgh.

  2. Collect Amoeba by centrifugation three days prior to use, wash, and resuspend without food. It is important that the Amoeba be starved for this exercise.

  3. If the dye is too strong, and the Amoeba are stained intensely blue, dilute the dye 1/10 or even 1/100.

  4. This material is readily available from local slaughter houses. If there is not one convenient to your location, and a local butcher will not help, rat brains can be substituted. Quantities will need to be adjusted accordingly.

  5. This solution is stable for about 5 days if refrigerated, and can be prepared ahead and used for multiple lab sessions.

  6. A salt bridge is simply a saturated KCl solution (in 2% (w/v) agar) placed within glass, polyethylene, or teflon capillary tubes and with platinum electrodes or commercially available calomel electrodes immersed within the agar. Thus, they bridge the gap between the solution being monitored and the rather large wire connections of a recording electrode.

  7. A suitable measurement can be made by using the millivolt potential scale on a good pH meter. It may require some assistance from the local physical chemist, or a physicist to construct the proper electrodes.

  8. Assume a thickness of 5 x 10^-7 cm if it was not measured.

  9. This will model the normal distribution of increased external Na^+ observed in vertebrate neurons. As the Na^+ diffuses into the center of the teflon cup, it will model the influx of ions associated with an action potential.

  10. Yields of myelin will vary depending upon the developmental age of the animal and upon the species. Adult rat brains will yield about 40-90 mg. of pure myelin per brain while the white matter from bovine brain will yield about 100 mg of pure myelin per gram of white matter. The purity will depend upon whether whole brain is used or just the white matter, with the latter yielding better results. Whole brains would contain a fair amount of microsomal membranes isolated along with the myelin membranes, and thus would have more impurities.

  11. The pellet contains mitochondria and myelin vessicles.

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Cell Biology Laboratory Manual
Dr. William H. Heidcamp, Biology Department, Gustavus Adolphus College,
St. Peter, MN 56082 -- cellab@gac.edu