8o SUBCELLULAR PARTICLES 



26. Palade, G. E. /. Biophys. Biochcm. Cytol. 2: 417, 1956. 



27. Palade, G. E. /. Biophys. Biochem. Cytol. 2, suppl.: 85, 1956. 



28. Palade, G. E. and K. R. Porter. /. Exper. Med. 100: 641, 1954. 



29. Palade, G. E. and G. Schidlowsky. Aiiat. Rec. 130: 352, 1958. 



30. Palade, G. E. and P. Siekevitz. /. Biophys. Biochem. Cytol. 2: 671, 1956. 



31. PoMERAT, C. M., C. G. Lefeber and D. McSmith. Ann. New York, Acad. Sci. 58: 131 1, 



1954- 



32. Porter, K. R. /. E.xper. Med. 97: 727, 1953. 



33. Schneider, W. C. /. Biol. Cheni. 176. 259, 1948. 



34. Schucher, R. AND L. E. HoKiN. /. Biol. Cheni. 210: 551, 1954. 



35. Scott, W. J. M. Am. J. Anut. 20: 237, 1916. 



36. Siekevitz, P. and G. E. Palade. /. Biophys. Biochem. Cytol. 4: 203, 1958. 



37. Siekevitz, P. and G. E. Palade. /. Biophys. Biochem. Cytol. 4: 309, 1958. 



38. Siekevitz, P. and G. E. Palade. /. Biophys. Biochem. Cytol. 4: 557, 1958. 



39. Siekevitz, P. and G. E. Palade. /. Biophys. Biochem. Cytol. 5: i, 1959. 



40. Sjostrand, F. S. and V. Hanzon. E.xper. Cell Res. 7: 393, 1954. 



41. Sjostrand, F. S. and V. Hanzon. Exper. Cell Res. 7: 415, 1954. 



42. Watanabe, Y. /. Electronmicroscopy (Japan) 3: 43, 1955. 



43. Watson, M. L. and P. Siekevitz. /. Biophys. Biochem. Cytol. 2: 639, 1956. 



44. Weiss, J. M. /. Exper. Med. 98: 607, 1953. 



45. ZiEGLER, D. M., A. W. Linnane, D. E. Green, C. M. S. Dass and H. Ris. Blochim. 

 et biophys. acta 28: 524, 1958. 



DISCUSSION 



V. R. Potter, G. E. Palade, D. E. Green, Spirtes, R. Weber, A. B. Novikoff, 

 ./. W. Littlefield, A. Marshak, C. L. Prosser, A. W. Swift 



Dr. Potter: In the case of mitochondria bearing fat droplets, will centrifugation 

 cause the combination to move up or down.' 



Dr. Palade: I do not know of any systematic work carried out to answer this ques- 

 tion, but I fMXSume that 'the combination' would be lighter than usual mitochondria. 

 Some results obtained by Lansing (17) on centrifuged Arbucia eggs may have some 

 bearing on this point. He found many mitochondria among the lipid droplets of the 

 'oil cap' at the centripetal pole of such eggs. These 'light' mitochondria were displaced 

 far away in the centripetal direction from the layer formed by the 'heavy' mitochon- 

 dria of the cell. In retrospect one may wonder whether Lansing's 'light mitochondria' 

 were not mitochondrial-lipid complexes similar to the ones just described. 



Dr. Green: Suggestion is made that the accumulation of lipid is due largely to the 

 fact that oxidation of fats is limited by the unavailability of citric cycle subtrates during 

 starvation. Synthesis of fat appears to be carried out largely by a nonmitochondrial 

 system. If synthesis were more rapid than oxidation, this accumulation would result. 

 Increased rate of oxidation can hardly explain the fact that fat actually accumulates. 



Dr. Palade: To assess the value of Dr. Green's suggestion one should know the con- 

 centration levels at which citric cycle substrates become a limiting factor in the oxida- 

 tion of fatty acids. As far as I know, such information is not yet available. One can 

 assume, however, that the concentrations needed are very low, since citric cycle sub- 



