INVESTIGADORES
GIUSTO Norma Maria
artículos
Título:
Synthesis of Retinal Ganglion Cell Phospholipids Is Under Control of an Endogenous Circadian Clock: Daily Variations in Enzyme Activities Enzyme Activities
Autor/es:
E GARBARINO PICO; A R CARPENTIERI,; P I CASTAGNET,; S J PASQUARÉ,; NORMA MARIA GIUSTO; B L CAPUTTO,; M E GUIDO,
Revista:
JOURNAL OF NEUROSCIENCE RESEARCH
Editorial:
Wiley -liss
Referencias:
Lugar: New Jersey; Año: 2004 vol. 76 p. 642 - 652
ISSN:
0360-4012
Resumen:
Retinal ganglion cells (RGCs) are major components of
the vertebrate circadian system. They send information
to the brain, synchronizing the entire organism to the
light-dark cycles. We recently reported that chicken
RGCs display daily variations in the biosynthesis of glycerophospholipids
in constant darkness (DD). It was unclear
whether this rhythmicity was driven by this population
itself or by other retinal cells. Here we show that
RGCs present circadian oscillations in the labeling of
[32P]phospholipids both in vivo in constant light (LL) and
in cultures of immunopuri.ed embryonic cells. In vivo,
there was greater [32P]orthophosphate incorporation into
total phospholipids during the subjective day. Phosphatidylinositol
(PI) was the most 32P-labeled lipid at all times
examined, displaying maximal levels during the subjective
day and dusk. In addition, a signi.cant daily variation
was found in the activity of distinct enzymes of the pathway
of phospholipid biosynthesis and degradation, such
as lysophospholipid acyltransferases (AT II), phosphatidate
phosphohydrolase (PAP), and diacylglycerol lipase
(DGL) in cell preparations obtained in DD, exhibiting differential
but coordinated temporal pro.les. Furthermore,
cultures of immunopuri.ed RGCs synchronized by medium
exchange displayed a circadian .uctuation in the
phospholipid labeling. The results demonstrate that
chicken RGCs contain circadian oscillators capable of
generating metabolic oscillations in the biosynthesis of
phospholipids autonomously. © 2004 Wiley-Liss, Inc.
2000).