INVESTIGADORES
ROTSTEIN Nora Patricia
artículos
Título:
Labeling of phosphatidylcholines of retina subcellular fractions by [14C] eicosatetraenoate (20:4 n-6), docosapentaenoate (22:5 n-3) and docosahexaenoate (22:6 n-3)
Autor/es:
ROTSTEIN, N.P.; AVELDAÑO, M.I.
Revista:
BIOCHIMICA AND BIOPHYSICA ACTA
Editorial:
Elsevier
Referencias:
Año: 1987 vol. 921 p. 235 - 245
ISSN:
0006-3002
Resumen:
The labeling of molecular species of phosphatidylcholine (PC) has been studied in bovine retinas incubated for 2 h with (1-14C)-labeled (n − 6) eicosatetraenoate (n − 3) docosapentaenoate and (n
− 3) docosahexaenoate (20:4, 22:5 and 22:6, respectively) and in four
subcellular fractions isolated after such incubations. Of the total
radioactivity incorporated in PC, the following percentages of the above
fatty acids, respectively, are found in its dipolyunsaturated species:
58, 56 and 53% in rod outer segments; 29, 41 and 49% in mitochondria;
24, 28 and 39% in microsomes; 12, 14 and 16% in postmicrosomal
supernatants; 28, 36 and 58% in entire retinas. The remainder
percentages are in tetra-, penta- and hexaenoic species of PC,
respectively. The levels of pentaenoic species in the PCs of all
fractions are similar, while tetraenes are lowest and hexaenes highest
in photoreceptor membranes. Dipolyunsaturated species are highly
concentrated in photoreceptor membranes, but are minor components of
mitochondrial, microsomal and cytosolic PC. The specific radioactivities
of tetraenoic, pentaenoic and hexaenoic PCs are decreasingly lower in
the following order: postmicrosomal supernatants, microsomes,
mitochondria, photoreceptor membranes. In contrast, the specific
radioactivities of dipolyunsaturated PCs are higher in mitochondria and
microsomes than in the other fractions, especially with 22:5 and 22:6.
It is suggested that mitochondria as well as the endoplasmic reticulum
could play a role in the synthesis and further modifications of
dipolyunsaturated PCs before being supplied to photoreceptor membranes.