HpEtsimplicated in primary mesenchyme cell differentiation of the sea urchin (Hemicentrotus pulcherrimus) embryo

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S33-S34 ◽  
Author(s):  
Daisuke Kurokawa ◽  
Takashi Kitajima ◽  
Keiko Mitsunaga-Nakatsubo ◽  
Shonan Amemiya ◽  
Hiraku Shimada ◽  
...  
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Marker Genes ◽  
Asymmetric Distribution ◽  
Specific Marker ◽  
Cell Stage ◽  
Mesenchyme Cell ◽  
Maternal Determinants ◽  
And Function

In sea urchin embryogenesis it has been suggested that the initial territories are specified by a combination of the asymmetric distribution of cytoplasmic determinants and cell-cell interactions. At the 60-cell stage blastomeres clonally originated from founder cells divide the embryo into five distinct territories: small micromeres, large micromeres, vegetal plate, oral ectoderm and aboral ectoderm. The territories are identified by the expression of specific marker genes and their cell lineages (Davidson, 1989, 1991). The large micromeres are thought to play a role as an organiser and initiate a cascade of signal transduction toward overlying cells (Davidson, 1989). In this model the large micromeres induce the overlying veg2 tier, specifying the vegetal plate (Ransick & Davidson, 1993, 1995). The veg2 tier then induces the overlying cells, which include gut cells and cells of the prospective ectodermal territories (Wikramanayakeet al., 1995; Wikramanayake & Klein, 1997). Thus, the large micromeres, which are the prospective primary mesenchyme cells (PMCs), play a key role in cell fate specification and axis determination during sea urchin embryogenesis. Previous data suggested that the large micromeres are autonomously specified to become PMCs by maternally inherited determinants (Okazaki, 1975; Kitajima & Okazaki, 1980). An important question in sea urchins embryogenesis is the identity and function of the proposed maternal determinants.

Altered expression of spatially regulated embryonic genes in the progeny of separated sea urchin blastomeres

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 567-579 ◽  
Author(s):  
D.L. Hurley ◽  
L.M. Angerer ◽  
R.C. Angerer
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Sea Water ◽  
Negative Control ◽  
Normal Embryo ◽  
Cell Stage ◽  
Mrna Accumulation ◽  
Altered Expression ◽  
Intact Embryo ◽  
Dissociated Cells

We have examined the importance of the extracellular environment on the ability of separated cells of sea urchin embryos (Strongylocentrotus purpuratus) to carry out patterns of mRNA accumulation and decay characteristic of intact embryos. Embryos were dissociated into individual blastomeres at 16-cell stage and maintained in calcium-free sea water so that daughter cells continuously separated. Levels of eleven different mRNAs in these cells were compared to those in control embryos when the latter reached mesenchyme blastula stage, by which time cells in major regions of the intact embryo have assumed distinctive patterns of message accumulation. Abrogation of interactions among cells resulted in marked differences in accumulation and/or turnover of the individual mRNAs, which are expressed with diverse temporal and spatial patterns of prevalence in intact embryos. In general, separated cells are competent to execute initial events of mRNA accumulation and decay that occur uniformly in most or all blastomeres of the intact embryo and are likely to be regulated by maternal molecules. The ability of separated cells to accumulate mRNAs that appear slightly later in development depends upon the presumptive tissue in which a given mRNA is found in the normal embryo. Messages that normally accumulate in cells at the vegetal pole also accumulate in dissociated cells either at nearly normal levels or at increased levels. In one such case, that of actin CyIIa, which is normally restricted to mesenchyme cells, in situ hybridization demonstrates that the fraction of dissociated cells expressing this message is 4- to 5-fold higher than in the normal embryo. In contrast, separated cells accumulate significant levels of a message expressed uniformly in the early ectoderm but are unable to execute accumulation and decay of different messages that distinguish oral and aboral ectodermal regions. These data are consistent with the idea that interactions among cells in the intact embryo are important for both positive and negative control of expression of different genes that are early indicators of the specification of cell fate.

Nuclear beta-catenin is required to specify vegetal cell fates in the sea urchin embryo

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 345-357 ◽  
Author(s):  
C.Y. Logan ◽  
J.R. Miller ◽  
M.J. Ferkowicz ◽  
D.R. McClay
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Beta Catenin ◽  
Cell Fate Specification ◽  
Cell Fates ◽  
Cell Stage ◽  
Animal Pole ◽  
Fate Specification ◽  
The Relationship ◽  
Vegetal Cell

Beta-catenin is thought to mediate cell fate specification events by localizing to the nucleus where it modulates gene expression. To ask whether beta-catenin is involved in cell fate specification during sea urchin embryogenesis, we analyzed the distribution of nuclear beta-catenin in both normal and experimentally manipulated embryos. In unperturbed embryos, beta-catenin accumulates in nuclei that include the precursors of the endoderm and mesoderm, suggesting that it plays a role in vegetal specification. Using pharmacological, embryological and molecular approaches, we determined the function of beta-catenin in vegetal development by examining the relationship between the pattern of nuclear beta-catenin and the formation of endodermal and mesodermal tissues. Treatment of embryos with LiCl, a known vegetalizing agent, caused both an enhancement in the levels of nuclear beta-catenin and an expansion in the pattern of nuclear beta-catenin that coincided with an increase in endoderm and mesoderm. Conversely, overexpression of a sea urchin cadherin blocked the accumulation of nuclear beta-catenin and consequently inhibited the formation of endodermal and mesodermal tissues including micromere-derived skeletogenic mesenchyme. In addition, nuclear beta-catenin-deficient micromeres failed to induce a secondary axis when transplanted to the animal pole of uninjected host embryos, indicating that nuclear beta-catenin also plays a role in the production of micromere-derived signals. To examine further the relationship between nuclear beta-catenin in vegetal nuclei and micromere signaling, we performed both transplantations and deletions of micromeres at the 16-cell stage and demonstrated that the accumulation of beta-catenin in vegetal nuclei does not require micromere-derived cues. Moreover, we demonstrate that cell autonomous signals appear to regulate the pattern of nuclear beta-catenin since dissociated blastomeres possessed nuclear beta-catenin in approximately the same proportion as that seen in intact embryos. Together, these data show that the accumulation of beta-catenin in nuclei of vegetal cells is regulated cell autonomously and that this localization is required for the establishment of all vegetal cell fates and the production of micromere-derived signals.

scholarly journals Cyclin D and cdk4 Are Required for Normal Development beyond the Blastula Stage in Sea Urchin Embryos

2002 ◽  
Vol 22 (13) ◽  
pp. 4863-4875 ◽  
Author(s):  
Jennifer C. Moore ◽  
Jan L. Sumerel ◽  
Bradley J. Schnackenberg ◽  
Jason A. Nichols ◽  
Athula Wikramanayake ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Normal Development ◽  
Sea Urchins ◽  
Ectopic Expression ◽  
Cyclin D ◽  
Blastula Stage ◽  
Cell Stage ◽  
Cell Cycles ◽  
Early Embryos ◽  
Cdk4 Expression

ABSTRACT cdk4 mRNA and protein are constitutively expressed in sea urchin eggs and throughout embryonic development. In contrast, cyclin D mRNA is barely detectable in eggs and early embryos, when the cell cycles consist of alternating S and M phases. Cyclin D mRNA increases dramatically in embryos at the early blastula stage and remains at a constant level throughout embryogenesis. An increase in cdk4 kinase activity occurs concomitantly with the increase in cyclin D mRNA. Ectopic expression of cyclin D mRNA in eggs arrests development before the 16-cell stage and causes eventual embryonic death, suggesting that activation of cyclin D/cdk4 in cleavage cell cycles is lethal to the embryo. In contrast, blocking cyclin D or cdk4 expression with morpholino antisense oligonucleotides results in normal development of early gastrula-stage embryos but abnormal, asymmetric larvae. These results suggest that in sea urchins, cyclin D and cdk4 are required for normal development and perhaps the patterning of the developing embryo, but may not be directly involved in regulating entry into the cell cycle.

Further studies of the effects of deprivation of sulfate on the early development of the sea urchin Paracentrotus lividus

Development ◽  
1965 ◽  
Vol 14 (3) ◽  
pp. 289-305
Author(s):  
J. Immers ◽  
J. Runnström
Keyword(s):  
Sea Urchin ◽  
Developmental Stages ◽  
Sea Water ◽  
Sea Urchins ◽  
Paracentrotus Lividus ◽  
The Other ◽  
Free Medium ◽  
Dominant Group ◽  
And Function ◽  
Early Developmental

The morphological effects of sulfate-free medium on sea urchin embryos were described in detail by Herbst (1904). Further studies were carried out by Lindahl (1936, 1942). He was the first to consider metabolic aspects of the rôle of sulfate in the development of the sea urchin. Immers (1956, 1959, 1961a and b, 1962) studied the distribution and function of acid mucopolysaccharides in early developmental stages of sea urchins, mainly Paracentrotus lividus. A dominant group of these acid polysaccharides are sulfated. Their location in the blastocoel, in the hyaline layer and in the lumen of the intestine could be demonstrated by staining of sectioned specimens with the ferri-acetic reagent of Hale (1946). In blastulae or gastrulae raised in sulfate-free sea water these regions are negative with respect to Hale staining (Immers, 1961b). On the other hand, the ectodermal nuclei of the animal region of the embryos are stained with the Hale reagent although the nuclei of the vegetal region remained unstained (1.c.).

scholarly journals Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development

2016 ◽  
Vol 283 (1826) ◽  
pp. 20152978 ◽  
Author(s):  
Chai-An Mao ◽  
Cavit Agca ◽  
Julie A. Mocko-Strand ◽  
Jing Wang ◽  
Esther Ullrich-Lüter ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Sea Urchin ◽  
Ganglion Cells ◽  
Sea Urchins ◽  
Photoreceptor Cells ◽  
Retinal Ganglion ◽  
Mammalian Retina ◽  
Morphological Differences ◽  
And Function ◽  
Tube Feet

Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus ( SpPou4f1/2 ), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2 . To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2 -null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus , SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures.

Fertilistion in sea urchins: how many different molecules are involved in gamete interaction and fusion?

Zygote ◽  
1994 ◽  
Vol 2 (1) ◽  
pp. 1-4 ◽  
Author(s):  
William J. Lennarz
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Structure And Function ◽  
Cell Surface Receptor ◽  
Egg Cell ◽  
Cell Surface Molecules ◽  
Surface Molecules ◽  
Surface Receptor ◽  
And Function

SummaryIt has been established that fertilisation in the sea urchin involves binding of acrosome-reacted sperm to an egg cell surface receptor. The structure and function of receptor, as well as the possible involvement of other cell surface molecules in the binding, fusion and activation events, is discussed.

Altering cell fates in sea urchin embryos by overexpressing SpOtx, an orthodenticle-related protein

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1489-1498 ◽  
Author(s):  
C.A. Mao ◽  
A.H. Wikramanayake ◽  
L. Gan ◽  
C.K. Chuang ◽  
R.G. Summers ◽  
...  
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Biological Effects ◽  
Gene Activation ◽  
Related Protein ◽  
Cell Fates ◽  
Cell Stage ◽  
Morphological Alterations ◽  
Transactivation Domains ◽  
Sea Urchin Embryo

While many general features of cell fate specification in the sea urchin embryo are understood, specific factors associated with these events remain unidentified. SpOtx, an orthodenticle-related protein, has been implicated as a transcriptional activator of the aboral ectoderm-specific Spec2a gene. Here, we present evidence that SpOtx has the potential to alter cell fates. SpOtx was found in the cytoplasm of early cleavage stage embryos and was translocated into nuclei between the 60- and 120-cell stage, coincident with Spec gene activation. Eggs injected with SpOtx mRNA developed into epithelial balls of aboral ectoderm suggesting that SpOtx redirected nonaboral ectoderm cells to an aboral ectoderm fate. At least three distinct domains on SpOtx, the homeobox and regions in the N-terminal and C-terminal halves of the protein, were required for the morphological alterations. These same N-terminal and C-terminal regions were shown to be transactivation domains in a yeast transactivation assay, indicating that the biological effects of overexpressing SpOtx were due to its action as a transcription factor. Our results suggest that SpOtx is involved in aboral ectoderm differentiation by activating aboral ectoderm-specific genes and that modulating its expression can lead to changes in cell fate.

scholarly journals A single-cell analysis of the molecular lineage of chordate embryogenesis

2020 ◽  
Author(s):  
Tengjiao Zhang ◽  
Yichi Xu ◽  
Kaoru Imai ◽  
Teng Fei ◽  
Guilin Wang ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Fate ◽  
Developmental Stages ◽  
Expression Profiles ◽  
Cell Types ◽  
Mapk Signaling ◽  
Modular Structure ◽  
Marker Genes ◽  
List Type ◽  
Cell Stage

SummaryIn multicellular organisms, a single zygote develops along divergent lineages to produce distinct cell types. What governs these processes is central to the understanding of cell fate specification and stem cell engineering. Here we used the protochordate model Ciona savignyi to determine gene expression profiles of every cell of single embryos from fertilization through the onset of gastrulation and provided a comprehensive map of chordate early embryonic lineage specification. We identified 47 cell types across 8 developmental stages up to the 110-cell stage in wild type embryos and 8 fate transformations at the 64-cell stage upon FGF-MAPK inhibition. The identities of all cell types were evidenced by in situ expression pattern of marker genes and expected number of cells based on the invariant lineage. We found that, for the majority of asymmetrical cell divisions, the bipotent mother cell shows predominantly the gene signature of one of the daughter fates, with the other daughter being induced by subsequent signaling. Our data further indicated that the asymmetric segregation of mitochondria in some of these divisions does not depend on the concurrent fate inducing FGF-MAPK signaling. In the notochord, which is an evolutionary novelty of chordates, the convergence of cell fate from two disparate lineages revealed modular structure in the gene regulatory network beyond the known master regulator T/Brachyury. Comparison to single cell transcriptomes of the early mouse embryo showed a clear match of cell types at the tissue level and supported the hypothesis of developmental-genetic toolkit. This study provides a high-resolution single cell dataset to understand chordate embryogenesis and the relationship between fate trajectories and the cell lineage.HighlightsTranscriptome profiles of 47 cell types across 8 stages in early chordate embryoBipotent mother in asymmetric division shows the default daughter fateModular structure of the notochord GRN beyond the known function of TInvariant lineage and manual cell isolation provide truth to trajectory analysis

scholarly journals Effects of Ocean Climate on Spatiotemporal Variation in Sea Urchin Settlement and Recruitment

2018 ◽  
Author(s):  
Daniel K. Okamoto ◽  
Stephen Schroeter ◽  
Daniel C. Reed
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Larval Settlement ◽  
Larval Transport ◽  
Climatic Fluctuations ◽  
Larval Recruitment ◽  
Purple Sea Urchin ◽  
Class Strength ◽  
Temporal And Spatial ◽  
And Function

AbstractSea urchins are voracious herbivores that influence the ecological structure and function of nearshore ecosystems throughout the world. Like many species that produce planktonic larvae, their recruitment is thought to be particularly sensitive to climatic fluctuations in temperature that directly or indirectly affect adult reproduction and larval transport and survival. Yet how climate alters sea urchin populations in space and time by modifying larval recruitment and year-class strength on the time-scales that regulate populations remains understudied. Using a, spatially replicated weekly-biweekly dataset spanning 27 years and 1100 km of coastline, we characterized seasonal, interannual, and spatial patterns of larval settlement of the purple sea urchin (Strongylocentrotus purpuratus). We show that large spatial differences in temporal patterns of larval settlement were associated with different responses to fluctuations in ocean temperature and climate. Importantly, we found a strong correlation between larval settlement and regional year class strength suggesting that such temporal and spatial variation in settlement plays an important role in controlling population dynamics. These results provide strong evidence over extensive temporal and spatial domains that climatic fluctuations shape broad-scale patterns of larval settlement and subsequent population structure of an important marine herbivore known to control the productivity, community state and provisioning services of marine ecosystems.

scholarly journals Rainbow-seq: combining cell lineage tracking with single-cell RNA sequencing in preimplantation embryos

2018 ◽  
Author(s):  
Fernando Biase ◽  
Qiuyang Wu ◽  
Riccardo Calandrelli ◽  
Marcelo Rivas-Astroza ◽  
Shuigeng Zhou ◽  
...  
Keyword(s):  
Cell Division ◽  
Single Cell ◽  
Cell Fate ◽  
Fluorescent Protein ◽  
Lineage Tracing ◽  
Preimplantation Embryos ◽  
Marker Genes ◽  
Regulation Of Transcription ◽  
Rna Seq ◽  
Cell Stage

SUMMARYSingle-cell RNA-seq experiments cannot record cell division history and therefore cannot directly connect intercellular differences at a later developmental stage to their progenitor cells. We developed Rainbow-seq to combine cell division lineage tracing with single-cell RNA-seq. With distinct fluorescent protein genes as lineage markers, Rainbow-seq enables each single-cell RNA-seq experiment to simultaneously read single-cell transcriptomes and decode the lineage marker genes. We traced the lineages deriving from each blastomere in two-cell mouse embryos and observed inequivalent contributions to the embryonic and abembryonic poles in 72% of the blastocysts evaluated. Rainbow-seq on four- and eight-cell embryos with lineage tracing triggered at two-cell stage exhibited remarkable transcriptome-wide differences between the two cell lineages at both stages, including genes involved in negative regulation of transcription and signaling. These data provide critical insights on cell fate choices in cleavage embryos. Rainbow-seq bridged a critical gap between cellular division history and single-cell RNA-seq assays.

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