Determination and morphogenesis in the sea urchin embryo

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 559-576 ◽  
Author(s):  
F.H. Wilt
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Secondary Phase ◽  
Animal Cells ◽  
Sea Urchin Embryo ◽  
Defect Isolation ◽  
Normal Larva ◽  
Mesenchyme Cells ◽  
The Stability ◽  
Almost All

The study of the sea urchin embryo has contributed importantly to our ideas about embryogenesis. This essay re-examines some issues where the concerns of classical experimental embryology and cell and molecular biology converge. The sea urchin egg has an inherent animal-vegetal polarity. An egg fragment that contains both animal and vegetal material will produce a fairly normal larva. However, it is not clear to what extent the oral-aboral axis is specified in embryos developing from meridional fragments. Newly available markers of the oral-aboral axis allow this issue to be settled. When equatorial halves, in which animal and vegetal hemispheres are separated, are allowed to develop, the animal half forms a ciliated hollow ball. The vegetal half, however, often forms a complete embryo. This result is not in accord with the double gradient model of animal and vegetal characteristics that has been used to interpret almost all defect, isolation and transplantation experiments using sea urchin embryos. The effects of agents used to animalize and vegetalize embryos are also due for re-examination. The classical animalizing agent, Zn2+, causes developmental arrest, not expression of animal characters. On the other hand, Li+, a vegetalizing agent, probably changes the determination of animal cells. The stability of these early determinative steps may be examined in dissociation-reaggregation experiments, but this technique has not been exploited extensively. The morphogenetic movements of primary mesenchyme are complex and involve a number of interactions. It is curious that primary mesenchyme is dispensable in skeleton formation since in embryos devoid of primary mesenchyme, the secondary mesenchyme cells will form skeletal elements. It is likely that during its differentiation the primary mesenchyme provides some of its own extracellular microenvironment in the form of collagen and proteoglycans. The detailed form of spicules made by primary mesenchyme is determined by cooperation between the epithelial body wall, the extracellular material and the inherent properties of primary mesenchyme cells. Gastrulation in sea urchins is a two-step process. The first invagination is a buckling, the mechanism of which is not understood. The secondary phase in which the archenteron elongates across the blastocoel is probably driven primarily by active cell repacking. The extracellular matrix is important for this repacking to occur, but the basis of the cellular-environmental interaction is not understood.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization and expression of msp130, a primary mesenchyme lineage-specific cell surface protein in the sea urchin embryo

Development ◽  
1987 ◽  
Vol 101 (2) ◽  
pp. 255-265 ◽  
Author(s):  
J.A. Anstrom ◽  
J.E. Chin ◽  
D.S. Leaf ◽  
A.L. Parks ◽  
R.A. Raff
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Sea Water ◽  
Surface Protein ◽  
Specific Cell ◽  
Cell Surface Protein ◽  
Sea Urchin Embryo ◽  
A Cell ◽  
Mesenchyme Cells ◽  
Primary Mesenchyme Cells

In this report, we use a monoclonal antibody (B2C2) and antibodies against a fusion protein (Leaf et al. 1987) to characterize msp130, a cell surface protein specific to the primary mesenchyme cells of the sea urchin embryo. This protein first appears on the surface of these cells upon ingression into the blastocoel. Immunoelectronmicroscopy shows that msp130 is present in the trans side of the Golgi apparatus and on the extracellular surface of primary mesenchyme cells. Four precursor proteins to msp130 are identified and we show that B2C2 recognizes only the mature form of msp130. We demonstrate that msp130 contains N-linked carbohydrate groups and that the B2C2 epitope is sensitive to endoglycosidase F digestion. Evidence that msp130 is apparently a sulphated glycoprotein is presented. The recognition of the B2C2 epitope of msp130 is disrupted when embryos are cultured in sulphate-free sea water. In addition, two-dimensional immunoblots show that msp130 is an acidic protein that becomes substantially less acidic in the absence of sulphate. We also show that two other independently derived monoclonal antibodies, IG8 (McClay et al. 1983; McClay, Matranga & Wessel, 1985) and 1223 (Carson et al. 1985), recognize msp130, and suggest this protein to be a major cell surface antigen of primary mesenchyme cells.

Cell interactions and mesodermal cell fates in the sea urchin embryo

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 43-51 ◽  
Author(s):  
Charles A. Ettensohn
Keyword(s):  
Sea Urchin ◽  
Cell Interactions ◽  
Cell Labeling ◽  
Cell Fates ◽  
Mesodermal Cell ◽  
Sea Urchin Embryo ◽  
Present Information ◽  
Cell Type Specific ◽  
Mesenchyme Cells

Cell interactions during gastrulation play a key role in the determination of mesodermal cell fates in the sea urchin embryo. An interaction between primary and secondary mesenchyme cells (PMCs and SMCs, respectively), the two principal populations of mesodermal cells, regulates the expression of SMC fates. PMCs are committed early in cleavage to express a skeletogenic phenotype. During gastrulation, they transmit a signal that suppresses the skeletogenic potential of a subpopulation of SMCs and directs these cells into an alternative developmental pathway. This review summarizes present information concerning the cellular basis of the PMC-SMC interaction, as analyzed by cell transplantation and ablation experiments, fluorescent cell labeling methods and the use of cell type-specific molecular markers. The nature and stability of SMC fate switching, the timing of the PMC-SMC interaction and its quantitative characteristics, and the lineage, numbers and normal fate of the population of skeletogenic SMCs are discussed. Evidence is presented indicating that PMCs and SMCs come into direct filopodial contact during the late gastrula stage, when the signal is transmitted. Finally, evolutionary questions raised by these studies are briefly addressed.

scholarly journals Culture of and experiments with sea urchin embryo primary mesenchyme cells

2019 ◽  
pp. 293-330
Author(s):  
Bradley Moreno ◽  
Allessandra DiCorato ◽  
Alexander Park ◽  
Kellen Mobilia ◽  
Regina Knapp ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Embryo ◽  
Mesenchyme Cells ◽  
Primary Mesenchyme Cells

scholarly journals The sea urchin – the ultimate herbivore and biogeographic variability in its ability to deforest kelp ecosystems

2013 ◽  
Author(s):  
Jarrett E Byrnes ◽  
Ladd E. Johnson ◽  
Sean D. Connell ◽  
Nick T. Shears ◽  
Selena M McMillan ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Large Scale ◽  
Sea Urchins ◽  
Meta Analysis ◽  
Kelp Forest ◽  
Rocky Reef ◽  
Rocky Reefs ◽  
Iconic Images ◽  
Balance Of Forces ◽  
Almost All

Barren rocky seafloor landscapes, denuded of almost all life by ravenous sea urchins, liberated from their predators, stands as one of the iconic images of trophic cascades in Ecology. While this paradigm has been cited in nearly every temperate rocky reef ecosystem across the globe, there is widespread disagreement as to its generality. Given their biology, sea urchins are clearly one of the ocean’s strongest herbivores in many systems, but where will their impact be strongest? Here we perform a global meta-analysis of sea urchin-kelp relationships in the field. We find that sea urchins appear to be able to control kelp abundances in any system where they can achieve high densities. Furthermore, their ability to create large-scale long-lasting barrens appears to be limited to biogeographic regions where they can achieve high consumptive potential. Based on the literature, we outline a conceptual model that examines when and where sea urchins should be able to have a strong regulating impact on kelp forest ecosystems. We suggest that many elements of global change may shift the balance of forces regulating sea urchin consumptive potential in these ecosystems. Given their ability to have strong impacts on temperate rocky reefs, these drivers need to be considered in concert with their effect on sea urchins when attempting to predict future change to marine ecosystems.

Cell-cell interactions regulate skeleton formation in the sea urchin embryo

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 833-840 ◽  
Author(s):  
N. Armstrong ◽  
J. Hardin ◽  
D.R. McClay
Keyword(s):  
Sea Urchin ◽  
Cell Interactions ◽  
Sea Urchin Embryo ◽  
Skeletal Pattern ◽  
Tissue Sensitivity ◽  
Mesenchyme Cells ◽  
Larval Skeleton ◽  
Skeleton Formation

In the sea urchin embryo, the primary mesenchyme cells (PMCs) make extensive contact with the ectoderm of the blastula wall. This contact is shown to influence production of the larval skeleton by the PMCs. A previous observation showed that treatment of embryos with NiCl2 can alter spicule number and skeletal pattern (Hardin et al. (1992) Development, 116, 671–685). Here, to explore the tissue sensitivity to NiCl2, experiments recombined normal or NiCl2-treated PMCs with either normal or NiCl2-treated PMC-less host embryos. We find that NiCl2 alters skeleton production by influencing the ectoderm of the blastula wall with which the PMCs interact. The ectoderm is responsible for specifying the number of spicules made by the PMCs. In addition, experiments examining skeleton production in vitro and in half- and quarter-sized embryos shows that cell interactions also influence skeleton size. PMCs grown in vitro away from interactions with the rest of the embryo, can produce larger spicules than in vivo. Thus, the epithelium of the blastula wall appears to provide spatial and scalar information that regulates skeleton production by the PMCs.

Pattern formation during gastrulation in the sea urchin embryo

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 33-41 ◽  
Author(s):  
David R. McClay ◽  
Norris A. Armstrong ◽  
Jeff Hardin
Keyword(s):  
Sea Urchin ◽  
Spatial Information ◽  
Cell Types ◽  
Cell Interactions ◽  
Pigment Cells ◽  
Original Position ◽  
Embryonic Cells ◽  
Sea Urchin Embryo ◽  
Mesenchyme Cells ◽  
Primary Mesenchyme Cells

The sea urchin embryo follows a relatively simple cell behavioral sequence in its gastrulation movements. To form the mesoderm, primary mesenchyme cells ingress from the vegetal plate and then migrate along the basal lamina lining the blastocoel. The presumptive secondary mesenchyme and endoderm then invaginate from the vegetal pole of the embryo. The archenteron elongates and extends across the blastocoel until the tip of the archenteron touches and attaches to the opposite side of the blastocoel. Secondary mesenchyme cells, originally at the tip of the archenteron, differentiate to form a variety of structures including coelomic pouches, esophageai muscles, pigment cells and other cell types. After migration of the secondary mesenchyme cells from their original position at the tip of the archenteron, the endoderm fuses with an invagination of the ventral ectoderm (the stomodaem), to form the mouth and complete the process of gastrulation. A larval skeleton is made by primary mesenchyme cells during the time of archenteron and mouth formation. A number of experiments have established that these morphogenetic movements involve a number of cell autonomous behaviors plus a series of cell interactions that provide spatial, temporal and scalar information to cells of the mesoderm and endoderm. The cell autonomous behaviors can be demonstrated by the ability of micromeres or endoderm to perform their morphogenetic functions if either is isolated and grown in culture. The requirement for cell interactions has been demonstrated by manipulative experiments where it has been shown that axial information, temporal information, spatial information and scalar information is obtained by mesoderm and endoderm from other embryonic cells. This information governs the cell autonomous behavior and places the cells in the correct embryonic context.

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