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  • 1
    Electronic Resource
    Electronic Resource
    Skeletogenic potential of induced secondary mesenchyme cells derived from the presumptive ectoderm in echinoid embryos (1997)
    Springer
    Development genes and evolution 206 (1997), S. 472-476 
    Details
    ISSN: 1432-041X
    Keywords: Key words Cell fate ; Skeletogenic potential ; Echinoid ; Induction ; Secondary mesenchyme cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  During the normal development of echinoids, an animal cap consisting of 8 mesomeres in a 16-cell stage embryo differentiates exclusively into ectoderm. Micromeres in an embryo at the same stage differentiate into primary mesenchyme cells (PMC) and coelomic pouch constituents. An animal cap and a quartet of micromeres were isolated from a 16-cell stage embryo and recombined to make a chimeric embryo devoid of presumptive endoderm and secondary mesenchyme cells (SMC). The PMC in the chimeric embryo were completely removed at the mesenchyme blastula stage. The PMC-depleted chimeric embryos formed an archenteron derived from the mesomeres. Some secondary mesenchyme-like cells (induced SMC) were released from the archenteron tip. A considerable fraction of the induced SMC formed the typical mesenchyme pattern after migrating into the vegetal region, synthesized skeletogenic mesenchyme cell-surface protein (msp130) and produced the larval skeleton. These findings indicate that induced SMC derived from the presumptive ectoderm have the same nature as natural SMC in both the timing of their release and their skeletogenic potential expressed in the absence of PMC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050077
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  • 2
    Electronic Resource
    Electronic Resource
    Alpha-actinin accumulation in the cortex of echinoderm eggs during fertilization (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 549-559 
    Details
    ISSN: 0886-1544
    Keywords: activation ; microinjection ; polar body ; sea urchin eggs ; starfish oocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Redistribution of alpha-actinin during fertilization was investigated by means of the microinjection of fluorescently labeled egg alpha-actinin in the sea urchin, Hemicentrotus pulcherrimus. Upon fertilization, labeled alpha-actinin accumulated locally around the sperm binding site, where the fertilization cone formed soon afterwards. The accumulation propagated all over the cortex within 10 sec after a latent period of 10-20 sec. When an egg in Na-free seawater was injected with both alpha-actinin and calcium buffer (intracellular free Ca2+ concentration = 9 μM), the accumulation of alpha-actinin was similar to that in normal seawater, which suggests that the accumulation did not depend on the increase in intracellular pH but only on the increase in the intracellular free Ca2+ concentration. In immature oocytes the accumulation was detected in the cortical region, including the huge protruding cytoplasm where the sperm entered. When labeled egg alpha-actinin was injected into starfish (Asterias amurensis) oocytes followed by insemination, it accumulated in the cortical layer in a manner similar to the case of sea urchin, except that the accumulation in fertilization cones of maturing oocytcs or reception cones of immature oocytes appeared ringlike and rodlike, respectively. Moreover, just after the arrival of the meiotic apparatus, egg alpha-actinin accumulated in the cortical region, where the formation of the polar body was expected. This suggests that the meiotic apparatus somehow induced the differentiation of the cortex so as to form a polar body. It is concluded that the cortical region where alpha-actinin accumulated coincided with the microfilament-rich region. This suggests that alpha-actinin plays a role in forming the cortical meshwork of actin filaments.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060603
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