Abstract
The renewal of fatty acids in the visual cells and pigment epithelium of the frog retina was studied by autoradiographic analysis of animals injected with tritiated palmitic, stearic, or arachidonic acids. Most of the radioactive material could be extracted from the retina with chloroform-methanol, indicating that the fatty acids had been esterified in lipids. Analysis of the extracts, after injection of [3H]palmitic acid, revealed that the radioactivity was predominantly in phospholipid. Palmitic acid was initially concentrated in the pigment epithelium, particularly in oil droplets which are storage sites for vitamin A esterified with fatty acid. The cytoplasm, but not the nucleus of these cells, was also heavily labeled. Radioactive fatty acid was bound immediately to the visual cell outer segment membranes, including detached rod membranes which had been phagocytized by the pigment epithelium. This is believed to be due to fatty acid exchange in phospholipid molecules already situated in the membranes. Gradually, the concentration of radioactive material in the visual cell outer segment membranes increased, apparently as a result of the addition of new phospholipid molecules, possibly augmented by the transfer from the pigment epithelium of esterified vitamin A. Injected fatty acid became particularly concentrated in new membranes which are continually assembled at the base of rod outer segments. This localized concentration was short-lived, apparently due to the rapid renewal of fatty acid. The results support the conclusion that rods renew the lipids of their outer segments by membrane replacement, whereas both rods and cones renew the membrane lipids by molecular replacement, including fatty acid exchange and replacement of phospholipid molecules in existing membranes.
Full Text
The Full Text of this article is available as a PDF (1.6 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ANDREWS J. S., FUTTERMAN S. METABOLISM OF THE RETINA. V. THE ROLE OF MICROSOMES IN VITAMIN A ESTERIFICATION IN THE VISUAL CYCLE. J Biol Chem. 1964 Dec;239:4073–4076. [PubMed] [Google Scholar]
- Akiyama M., Sakagami T. Exchange of mitochondrial lecithin and cephalin with those in rat liver microsomes. Biochim Biophys Acta. 1969 Jul 29;187(1):105–112. [PubMed] [Google Scholar]
- Anderson R. E. Lipids of ocular tissues. IV. A comparison of the phospholipids from the retina of six mammalian species. Exp Eye Res. 1970 Oct;10(2):339–344. doi: 10.1016/s0014-4835(70)80046-x. [DOI] [PubMed] [Google Scholar]
- Anderson R. E., Maude M. B. Phospholipids of bovine outer segments. Biochemistry. 1970 Sep 1;9(18):3624–3628. doi: 10.1021/bi00820a019. [DOI] [PubMed] [Google Scholar]
- Anderson R. E., Sperling L. Lipids of ocular tissues. VII. Positional distribution of the fatty acids in the phospholipids of bovine retina rod outer segments. Arch Biochem Biophys. 1971 Jun;144(2):673–677. doi: 10.1016/0003-9861(71)90374-2. [DOI] [PubMed] [Google Scholar]
- Baker R. R., Thompson W. Positional distribution and turnover of fatty acids in phosphatidic acid, phosphinositides, phosphatidylcholine and phosphatidylethanolamine in rat brain in vivo. Biochim Biophys Acta. 1972 Aug 11;270(4):489–503. doi: 10.1016/0005-2760(72)90114-2. [DOI] [PubMed] [Google Scholar]
- Bargoot F. G., Williams T. P., Beidler L. M. The localization of radioactive amino acid taken up into the outer segments of frog (Rana pipiens) rods. Vision Res. 1969 Mar;9(3):385–391. doi: 10.1016/0042-6989(69)90085-6. [DOI] [PubMed] [Google Scholar]
- Basinger S. F., Hall M. O. Rhodopsin biosynthesis in vitro. Biochemistry. 1973 May 8;12(10):1996–2003. doi: 10.1021/bi00734a025. [DOI] [PubMed] [Google Scholar]
- Blasie J. K., Worthington C. R. Planar liquid-like arrangement of photopigment molecules in frog retinal receptor disk membranes. J Mol Biol. 1969 Feb 14;39(3):417–439. doi: 10.1016/0022-2836(69)90136-3. [DOI] [PubMed] [Google Scholar]
- Bok D., Young R. W. The renewal of diffusely distributed protein in the outer segments of rods and cones. Vision Res. 1972 Feb;12(2):161–168. doi: 10.1016/0042-6989(72)90108-3. [DOI] [PubMed] [Google Scholar]
- Borggreven J. M., Daemen F. J., Bonting S. L. Biochemical aspects of the visual process. VI. The lipid composition of native and hexane-extracted cattle rod outer segments. Biochim Biophys Acta. 1970 Mar 10;202(2):374–381. [PubMed] [Google Scholar]
- Cone R. A. Rotational diffusion of rhodopsin in the visual receptor membrane. Nat New Biol. 1972 Mar 15;236(63):39–43. doi: 10.1038/newbio236039a0. [DOI] [PubMed] [Google Scholar]
- DOWLING J. E. Chemistry of visual adaptation in the rat. Nature. 1960 Oct 8;188:114–118. doi: 10.1038/188114a0. [DOI] [PubMed] [Google Scholar]
- Dratz E. A., Gaw J. E., Schwartz S., Ching W. M. Molecular organization of photoreceptor membranes of rod outer segments. Nat New Biol. 1972 May 24;237(73):99–102. doi: 10.1038/newbio237099a0. [DOI] [PubMed] [Google Scholar]
- Eichberg J., Hess H. H. The lipid composition of frog retinal rod outer segments. Experientia. 1967 Dec 15;23(12):993–994. doi: 10.1007/BF02136402. [DOI] [PubMed] [Google Scholar]
- Futterman S., Downer J. L., Hendrickson A. Effect of essential fatty acid deficiency on the fatty acid composition, morphology, and electroretinographic response of the retina. Invest Ophthalmol. 1971 Feb;10(2):151–156. [PubMed] [Google Scholar]
- HUBBARD R., COLMAN A. D. Vitamin-A content of the frog eye during light and dark adaptation. Science. 1959 Oct 16;130(3381):977–978. doi: 10.1126/science.130.3381.977. [DOI] [PubMed] [Google Scholar]
- HUBBARD R., DOWLING J. E. Formation and utilization of 11-cis vitamin A by the eye tissues during light and dark adaptation. Nature. 1962 Jan 27;193:341–343. doi: 10.1038/193341a0. [DOI] [PubMed] [Google Scholar]
- Hall M. O., Bok D., Bacharach A. D. Biosynthesis and assembly of the rod outer segment membrane system. Formation and fate of visual pigment in the frog retina. J Mol Biol. 1969 Oct 28;45(2):397–406. doi: 10.1016/0022-2836(69)90114-4. [DOI] [PubMed] [Google Scholar]
- Hall M. O., Bok D., Bacharach A. D. Visual pigment renewal in the mature frog retina. Science. 1968 Aug 23;161(3843):787–789. doi: 10.1126/science.161.3843.787. [DOI] [PubMed] [Google Scholar]
- Ishikawa T., Yamada E. The degradation of the photoreceptor outer segment within the pigment epithelial cell of rat retina. J Electron Microsc (Tokyo) 1970;19(1):85–99. [PubMed] [Google Scholar]
- KRINSKY N. I. The enzymatic esterification of vitamin A. J Biol Chem. 1958 Jun;232(2):881–894. [PubMed] [Google Scholar]
- Korenbrot J. I., Brown D. T., Cone R. A. Membrane characteristics and osmotic behavior of isolated rod outer segments. J Cell Biol. 1973 Feb;56(2):389–398. doi: 10.1083/jcb.56.2.389. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lettré H., Paweletz N. Probleme der elektronenmikroskopischen Autoradiographie. Naturwissenschaften. 1966 Jun;53(11):268–271. doi: 10.1007/BF00621640. [DOI] [PubMed] [Google Scholar]
- Matsubara T., Miyata M., Mizuno K. Radioisotopic studies on renewal of opsin. Vision Res. 1968 Sep;8(9):1139–1143. doi: 10.1016/0042-6989(68)90023-0. [DOI] [PubMed] [Google Scholar]
- Mulder E., van Deenen L. L. Metabolism of red-cell lipids. I. Incorporation in vitro of fatty acids into phospholipids from mature erythrocytes. Biochim Biophys Acta. 1965 Jul 7;106(1):106–117. doi: 10.1016/0005-2760(65)90099-8. [DOI] [PubMed] [Google Scholar]
- OLIVEIRA M. M., VAUGHAN M. INCORPORATION OF FATTY ACIDS INTO PHOSPHOLIPIDS OF ERYTHROCYTE MEMBRANES. J Lipid Res. 1964 Apr;5:156–162. [PubMed] [Google Scholar]
- Poincelot R. P., Abrahamson E. W. Fatty acid composition of bovine rod outer segments and rhodopsin. Biochim Biophys Acta. 1970 Mar 10;202(2):382–385. doi: 10.1016/0005-2760(70)90202-x. [DOI] [PubMed] [Google Scholar]
- Reed C. F. Phospholipid exchange between plasma and erythrocytes in man and the dog. J Clin Invest. 1968 Apr;47(4):749–760. doi: 10.1172/JCI105770. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Robinson W. E., Gordon-Walker A., Bownds D. Molecular weight of frog rhodopsin. Nat New Biol. 1972 Jan 26;235(56):112–114. doi: 10.1038/newbio235112a0. [DOI] [PubMed] [Google Scholar]
- Scherphof G. L., van Deenen L. L. On the pathways of fatty acid incorporation into the lipids of subcellular particles of rat liver and into erythrocytes. Biochim Biophys Acta. 1966 Feb 14;113(2):417–420. doi: 10.1016/s0926-6593(66)80087-5. [DOI] [PubMed] [Google Scholar]
- Shohet S. B. Release of phospholipid fatty acid from human erythrocytes. J Clin Invest. 1970 Sep;49(9):1668–1678. doi: 10.1172/JCI106384. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shohet S. B. The apparent transfer of fatty acid from phosphatidylcholine to phosphatidylethanolamine in human erythrocytes. J Lipid Res. 1971 Mar;12(2):139–142. [PubMed] [Google Scholar]
- Stein O., Stein Y. Lipid synthesis, intracellular transport, and secretion. II. Electron microscopic radioautographic study of the mouse lactating mammary gland. J Cell Biol. 1967 Jul;34(1):251–263. doi: 10.1083/jcb.34.1.251. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stein O., Stein Y. Lipid synthesis, intracellular transport, storage, and secretion. I. Electron microscopic radioautographic study of liver after injection of tritiated palmitate or glycerol in fasted and ethanol-treated rats. J Cell Biol. 1967 May;33(2):319–339. doi: 10.1083/jcb.33.2.319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Swartz J. G., Mitchell J. E. Biosynthesis of retinal phospholipids: incorporation of radioactivity from labeled phosphorylcholine and cytidine diphosphate choline. J Lipid Res. 1970 Nov;11(6):544–550. [PubMed] [Google Scholar]
- Wirtz K. W., Zilversmit D. B. Exchange of phospholipids between liver mitochondria and microsomes in vitro. J Biol Chem. 1968 Jul 10;243(13):3596–3602. [PubMed] [Google Scholar]
- Wirtz K. W., Zilversmit D. B. The use of phenobarbital and carbon tetrachloride to examine liver phospholipid exchange in intact rats. Biochim Biophys Acta. 1969 Dec 17;187(4):468–476. doi: 10.1016/0005-2760(69)90043-5. [DOI] [PubMed] [Google Scholar]
- Worthington C. R. Structure of photoreceptor membranes. Fed Proc. 1971 Jan-Feb;30(1):57–63. [PubMed] [Google Scholar]
- Young R. W. A difference between rods and cones in the renewal of outer segment protein. Invest Ophthalmol. 1969 Apr;8(2):222–231. [PubMed] [Google Scholar]
- Young R. W. An hypothesis to account for a basic distinction between rods and cones. Vision Res. 1971 Jan;11(1):1–5. doi: 10.1016/0042-6989(71)90201-x. [DOI] [PubMed] [Google Scholar]
- Young R. W., Bok D. Autoradiographic studies on the metabolism of the retinal pigment epithelium. Invest Ophthalmol. 1970 Jul;9(7):524–536. [PubMed] [Google Scholar]
- Young R. W., Bok D. Participation of the retinal pigment epithelium in the rod outer segment renewal process. J Cell Biol. 1969 Aug;42(2):392–403. doi: 10.1083/jcb.42.2.392. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Young R. W., Droz B. The renewal of protein in retinal rods and cones. J Cell Biol. 1968 Oct;39(1):169–184. doi: 10.1083/jcb.39.1.169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Young R. W. Passage of newly formed protein through the connecting cilium of retina rods in the frog. J Ultrastruct Res. 1968 Jun;23(5):462–473. doi: 10.1016/s0022-5320(68)80111-x. [DOI] [PubMed] [Google Scholar]
- Young R. W. Renewal systems in rods and cones. Ann Ophthalmol. 1973 Aug;5(8):843–854. [PubMed] [Google Scholar]
- Young R. W. Shedding of discs from rod outer segments in the rhesus monkey. J Ultrastruct Res. 1971 Jan;34(1):190–203. doi: 10.1016/s0022-5320(71)90014-1. [DOI] [PubMed] [Google Scholar]
- Young R. W. The renewal of photoreceptor cell outer segments. J Cell Biol. 1967 Apr;33(1):61–72. doi: 10.1083/jcb.33.1.61. [DOI] [PMC free article] [PubMed] [Google Scholar]