Development of Ca²(+) signaling mechanisms and cell motility in presumptive ectodermal cells during amphibian gastrulation.
This study investigated the development of Ca²(+) signaling mechanisms and their role in initiating morphogenetic cell movement in the presumptive ectoderm of Japanese newt (Cynops pyrrhogaster) during gastrulation. Histochemical staining using fluorescently labeled ryanodine and dihydropyridine probes revealed that dihydropyridine receptor (L-type Ca²(+) channels) appeared in stage 12b embryos, while ryanodine receptors were expressed in both stage 11 and 12b embryos. Transmission electron microscopy of stage 12b embryos showed abundant peripheral couplings, which are couplings of the endoplasmic reticulum and cell membrane with an approximate 12 nm gap. Caffeine increased the intracellular free Ca²(+) concentration ([Ca²(+)](i)) in presumptive ectodermal cells isolated from both stage 11 and 12b embryos, while (±)-Bay K 8644 ((±)-BayK) increased [Ca²(+)](i) in cells isolated from stage 12b embryos, but not in cells isolated from stage 11 embryos. Dantrolene and nifedipine completely inhibited increases in [Ca²(+)](i) after treatment with caffeine and (±)-BayK, respectively. Caffeine activated the motility of cells isolated from both stage 11 and 12b embryos, but (±)-BayK only activated the motility of cells isolated from stage 12b embryos. These findings suggested that formation of the Ca²(+) -induced Ca²(+) release system in presumptive ectodermal cells during gastrulation plays an important role in the initiation and execution of epibolic extension.
Department of Anatomy, Saitama Medical University, Iruma, Japan.
Kazuhiro
K
Takano
Shuichi
S
Obata
Shinji
S
Komazaki
Mika
M
Masumoto
Tsutomu
T
Oinuma
Yuzuru
Y
Ito
Takashi
T
Ariizumi
Hiroaki
H
Nakamura
Makoto
M
Asashima
D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D004475:Ectoderm / Q000196:embryology / Q000378:metabolism; D054262:Gastrulation / Q000502:physiology*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012455:Salamandridae / Q000196:embryology* / Q000378:metabolism*
D020746:Calcium Channels, L-Type; D019837:Ryanodine Receptor Calcium Release Channel