INVESTIGADORES
AYBAR Manuel Javier
artículos
Título:
Participation of GM1 ganglioside in Bufo arenarum gastrulation
Autor/es:
MANUEL J. AYBAR; SUSANA B. GENTA; ALICIA SÁNCHEZ RIERA; SARA S. SÁNCHEZ
Revista:
JOURNAL OF EXPERIMENTAL ZOOLOGY
Editorial:
John Wiley & Sons
Referencias:
Lugar: USA; Año: 2000 vol. 286 p. 457 - 472
ISSN:
0022-104X
Resumen:
In the present paper we established the ganglioside composition of the
blastula and gastrula stages of the anuran amphibian Bufo arenarum, two
relevant stages characterized by dynamic changes in morphology and
cellular rearrangements. Densitometric studies evidenced that GD1a and
GT1b were the more abundant gangliosides of the blastula embryos
whereas GM1 and GM2 were the predominant species in gastrula embryos.
Analysis of ganglioside abundance indicates that the "a" and "b"
synthesis pathways perform similar biosynthetic activities in the
blastula stage, in contrast to the gastrula stage in which a marked
predominance of the "a" pathway occurred. The spatio-temporal
expression of GM1 and of polygangliotetraosyl ceramides (pGTC) was
investigated by wholemount immunocytochemistry using cholera toxin B
subunit (CTB) and an affinity purified human anti-GM1 antibody. The
pGTC were detected as GM1 after treatment with neuraminidase.
Blastomeres from the inner surface of the blastocoelic roof (BCR) of
blastula embryos were GM1 and pGTC positive. At midgastrula stage,
embryos showed an increased labeling on the inner surface of BCR. To
establish whether the GM1 ganglioside was involved in the gastrulation
processes, CTB, anti-GM1 antibodies and anti-GM1 Fab' fragments were
microinjected into the blastocoel cavity of blastula embryos. Treatment
with the probes blocked gastrulation. Scanning electron microscopy
analysis of blocked embryos revealed that mesodermal cell migration,
radial interdigitation, and convergent extension movements were
affected. The blocking of gastrulation was correlated with the absence
of fibronectin and EP3/EP4 on the inner surface of blastocoelic roof of
CTB- or anti-GM1 treated embryos. Results show that the GM1 ganglioside
is differentially expressed by embryonic cells and participates in the
morphogenetic processes of amphibian gastrulation. J. Exp. Zool.
286:457-472, 2000.