Origin and behaviour of pigment cells in sea urchin embryos

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S42-S43 ◽  
Author(s):  
Tetsuya Kominami
Keyword(s):  
Sea Urchin ◽  
Pigment Cell ◽  
Cell Lineage ◽  
Pigment Cells ◽  
Cleavage Stage ◽  
Fate Map ◽  
Blastula Stage ◽  
Cell Stage ◽  
Stage Embryo ◽  
Founder Cells

Sea urchin pluteus larvae contain dozens of pigment cells in their ectoderm. These pigment cells are the descendants of the veg2 blastomeres of the 60-cell stage embryo. According to the fate map made by Ruffins and Ettensohn, the prospective pigment cells occupy the central region of the vegetal plate. Most of these prospective pigment cells exclusively give rise to pigment cells. Therefore, specification of the pigment cell lineage should occur at some point between the 60-cell and mesenchyme blastula stage. However, the detailed process of the specification of the pigment lineage is unknown.When are pigment cells specified? Are cell interactions necessary for the specification? Do founder cells exist? To answer these questions, I treated embryos with Ca2+-free seawater during the cleavage stage and examined the number of pigment cells observed in pluteus larvae. Treatment at 5.5–8.5 h and especially 7.5–10.5 h postfertilisation markedly reduced the number of pigment cells. The decrease was statistically significant. On the other hand, the treatment at 3.5–6.5 h or 9.5–12.5 h never reduced the number of pigment cells. By examining the frequency of the appearance of embryos whose numbers of pigment cells were less than 20, it was also found that the numbers of pigment cells were frequently in multiples of 4. Embryos having 4, 8, 12, 16 and 20 pigment cells were more frequently observed. Statistics indicated that the frequency of appearance was not random. These results indicated that cell contacts are necessary for the specification of pigment cells and that the specification occurs from 7 to 10 h postfertilisation. The results also suggest that the founder cells, if they exist, divide twice before they differentiate into pigment cells.

Spatial and temporal expression pattern during sea urchin embryogenesis of a gene coding for a protease homologous to the human protein BMP-1 and to the product of the Drosophila dorsal-ventral patterning gene tolloid

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 147-163 ◽  
Author(s):  
T. Lepage ◽  
C. Ghiglione ◽  
C. Gache
Keyword(s):  
Sea Urchin ◽  
Catalytic Domain ◽  
Intracellular Localization ◽  
Regulation Of Gene Expression ◽  
Drosophila Embryo ◽  
Limited Area ◽  
Fate Map ◽  
Blastula Stage ◽  
Cell Stage ◽  
Short Period

A cDNA clone coding for a sea urchin embryonic protein was isolated from a prehatching blastula lambda gt11 library. The predicted translation product is a secreted 64 × 10(3) Mr enzyme designated as BP10. The protein contains several domains: a signal peptide, a putative propeptide, a catalytic domain with an active center typical of a Zn(2+)-metalloprotease, an EGF-like domain and two internal repeats similar to repeated domains found in the C1s and C1r serine proteases of the complement cascade. The BP10 protease is constructed with the same domains as the human bone morphogenetic protein BMP-1, a protease described as a factor involved in bone formation, and as the recently characterized product of the tolloid gene which is required for correct dorsal-ventral patterning of the Drosophila embryo. The transcription of the BP10 gene is transiently activated around the 16- to 32-cell stage and the accumulation of BP10 transcripts is limited to a short period at the blastula stage. By in situ hybridization with digoxygenin-labelled RNA probes, the BP10 transcripts were only detected in a limited area of the blastula, showing that the transcription of the BP10 gene is also spatially controlled. Antibodies directed against a fusion protein were used to detect the BP10 protein in embryonic extracts. The protein is first detected in early blastula stages, its level peaks in late cleavage, declines abruptly before ingression of primary mesenchyme cells and remains constant in late development. The distribution of the BP10 protein during its synthesis and secretion was analysed by immunostaining blastula-stage embryos. The intracellular localization of the BP10 staining varies with time. The protein is first detected in a perinuclear region, then in an apical and submembranous position just before its secretion into the perivitelline space. The protein is synthesized in a sharply delimited continuous territory spanning about 70% of the blastula. Comparison of the size and orientation of the labelled territory in the late blastula with the fate map of the blastula stage embryo shows that the domain in which the BP10 gene is expressed corresponds to the presumptive ectoderm. Developing embryos treated with purified antibodies against the BP10 protein and with synthetic peptides derived from the EGF-like domain displayed perturbations in morphogenesis and were radialized to various degrees. These results are consistent with a role for BP10 in the differentiation of ectodermal lineages and subsequent patterning of the embryo. On the basis of these results, we speculate that the role of BP10 in the sea urchin embryo might be similar to that of tolloid in Drosophila. We discuss the idea that the processes of spatial regulation of gene expression along the animal-vegetal in sea urchin and dorsal-ventral axes in Drosophila might have some similarities and might use common elements.

scholarly journals Macromere cell fates during sea urchin development

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1085-1091 ◽  
Author(s):  
R.A. Cameron ◽  
S.E. Fraser ◽  
R.J. Britten ◽  
E.H. Davidson
Keyword(s):  
Sea Urchin ◽  
Pigment Cell ◽  
Cell Lineage ◽  
Cell Types ◽  
Cellular Migration ◽  
The Other ◽  
Pigment Cells ◽  
Basal Cells ◽  
Cell Fates ◽  
Gut Pigment

This paper examines the cell lineage relationships and cell fates in embryos of the sea urchin Strongylocentrotus purpuratus leading to the various cell types derived from the definitive vegetal plate territory or the veg2 tier of cells. These cell types are gut, pigment cells, basal cells and coelomic pouches. They are cell types that constitute embryonic structures through cellular migration or rearrangement unlike the relatively non-motile ectoderm cell types. For this analysis, we use previous knowledge of lineage to assign macromeres to one of four types: VOM, the oral macromere; VAM, the aboral macromere, right and left VLM, the lateral macromeres. Each of the four macromeres contributes progeny to all of the cell types that descend from the definitive vegetal plate. Thus in the gut each macromere contributes to the esophagus, stomach and intestine, and the stripe of labeled cells descendant from a macromere reflects the re-arrangement of cells that occurs during archenteron elongation. Pigment cell contributions exhibit no consistent pattern among the four macromeres, and are haphazardly distributed throughout the ectoderm. Gut and pigment cell contributions are thus radially symmetrical. In contrast, the VOM blastomere contributes to both of the coelomic pouches while the other three macromeres contribute to only one or the other pouch. The total of the macromere contribution amounts to 60% of the cells constituting the coelomic pouches.

A fate map of the vegetal plate of the sea urchin (Lytechinus variegatus) mesenchyme blastula

Development ◽  
1996 ◽  
Vol 122 (1) ◽  
pp. 253-263 ◽  
Author(s):  
S.W. Ruffins ◽  
C.A. Ettensohn
Keyword(s):  
Sea Urchin ◽  
Single Cells ◽  
Cell Types ◽  
Lineage Tracing ◽  
Lytechinus Variegatus ◽  
Fate Map ◽  
Blastula Stage ◽  
Cell Stage ◽  
Mesodermal Cell ◽  
Single Blastomeres

Previous lineage tracing experiments have shown that the vegetal blastomers of cleavage stage embryos give rise to all the mesoderm and endoderm of the sea urchin larva. In these studies, vegetal blastomers were labeled no later than the sixth cleavage division (60-64 cell stage). In an earlier study we showed that single cells in the vegetal plate of the blastula stage Lytechinus variegatus embryo could be labeled in situ with the fluorescent, lipophilic dye, DiI(C18), and that cells labeled in the central region of the vegetal plate of the mesenchyme blastula primarily gave rise to homogeneous clones consisting of a single secondary mesenchyme cell (SMC) type (Ruffins and Ettensohn (1993) Dev. Biol. 160, 285–288). Our clonal labeling showed that a detailed fate map could be generated using the DiI(C18) labeling technique. Such a fate map could provide information about the spatial relationships between the precursors of specific mesodermal and endodermal cell types and information concerning the movements of these cells during gastrulation and later embryogenesis. We have used this method to construct the first detailed fate map of the vegetal plate of the sea urchin embryo. Ours is a latitudinal map; mapping from the plate center, where the mesodermal precursors reside, through the region which contains the endodermal precursors and across the ectodermal boundary. We found that the precursors of certain SMC types are segregated in the mesenchyme blastula stage vegetal plate and that prospective germ layers reside within specific boundaries. To determine whether the vegetal plate is radially symmetrical with respect to mesodermal cell fates, single blastomeres of four cell stage embryos were injected with lysyl-rhodamine dextran (LRD). The resulting ectodermal labeling patterns were classified and correlated with the SMC types labeled. This analysis indicates that the dorsal and ventral blastomers do not contribute equally to SMC derivatives in L. variegatus.

Incorporation of Uridine in Cleavage Stage Eggs of the Sea Urchin Paracentrotus Lividus

1971 ◽  
Vol 26 (8) ◽  
pp. 816-821 ◽  
Author(s):  
Larry E. Bockstahler
Keyword(s):  
Ion Exchange ◽  
Sea Urchin ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Paracentrotus Lividus ◽  
Cleavage Stage ◽  
Early Cleavage ◽  
Cell Stage ◽  
Cleavage Stages ◽  
Layer Chromatography

Incorporation of uridine in cleavage stage eggs of the sea urchin Paracentrotus lividus was investigated. It was shown by ion exchange and thin layer chromatography that most of the uridine taken up during the 16-cell stage was converted into UTP with some incorporation into UDP and UMP. Conversion of uridine to these phosphorylated nucleosides occurred throughout early cleavage stages. A very small amount of uridine taken up by cleavage stage eggs is incorporated into RNA heterogeneous in size. This RNA was examined by polyacrylamide gel electrophoresis.

Zebrafish Pigment Pattern Formation: Insights into the Development and Evolution of Adult Form

2019 ◽  
Vol 53 (1) ◽  
pp. 505-530 ◽  
Author(s):  
Larissa B. Patterson ◽  
David M. Parichy
Keyword(s):  
Pattern Formation ◽  
Pigment Cell ◽  
Cell Lineage ◽  
Pigment Cells ◽  
Cellular Interactions ◽  
Lineage Specification ◽  
Pigment Pattern ◽  
Adult Form ◽  
Pattern Development ◽  
Pigment Patterns

Vertebrate pigment patterns are diverse and fascinating adult traits that allow animals to recognize conspecifics, attract mates, and avoid predators. Pigment patterns in fish are among the most amenable traits for studying the cellular basis of adult form, as the cells that produce diverse patterns are readily visible in the skin during development. The genetic basis of pigment pattern development has been most studied in the zebrafish, Danio rerio. Zebrafish adults have alternating dark and light horizontal stripes, resulting from the precise arrangement of three main classes of pigment cells: black melanophores, yellow xanthophores, and iridescent iridophores. The coordination of adult pigment cell lineage specification and differentiation with specific cellular interactions and morphogenetic behaviors is necessary for stripe development. Besides providing a nice example of pattern formation responsible for an adult trait of zebrafish, stripe-forming mechanisms also provide a conceptual framework for posing testable hypotheses about pattern diversification more broadly. Here, we summarize what is known about lineages and molecular interactions required for pattern formation in zebrafish, we review some of what is known about pattern diversification in Danio, and we speculate on how patterns in more distant teleosts may have evolved to produce a stunningly diverse array of patterns in nature.

Interactions of different vegetal cells with mesomeres during early stages of sea urchin development

Development ◽  
1991 ◽  
Vol 112 (3) ◽  
pp. 881-890 ◽  
Author(s):  
O. Khaner ◽  
F. Wilt
Keyword(s):  
Sea Urchin ◽  
Normal Development ◽  
Pigment Cells ◽  
Regional Differentiation ◽  
Cell Type ◽  
Animal Cells ◽  
Cell Stage ◽  
Latent Ability ◽  
A Cell ◽  
Poorly Differentiated

It has been known from results obtained in the classical experiments on sea urchin embryos that cell isolation and transplantation showed extensive interactions between the early blastomeres and/or their descendants. In the experiments reported here a systematic reexamination of recombination of mesomeres and their progeny (which come from the animal hemisphere) with various vegetal cells derived from blastomeres of the 32- and 64-cell stage was carried out. Cells were marked with lineage tracers to follow which cell gave rise to what structures, and newly available molecular markers have been used to analyze different structures characteristic of regional differentiation. Large micromeres form spicules and induce gut and pigment cells in mesomeres, conforming to previous results. Small micromeres, a cell type not heretofore examined, gave rise to no recognizable structure and had very limited ability to evoke poorly differentiated gut tissue in mesomeres. Macromeres and their descendants, Veg 1 and Veg 2, form primarily what their normal fate dictated, though both did have some capacity to form spicules, presumably by formation from secondary mesenchyme. Macromeres and their descendants were not potent inducers of vegetal structures in animal cells, but they suppress the latent ability of mesomeres to form vegetal structures. The results lead us to propose that the significant interactions during normal development may be principally suppressive effects of mesomeres on one another and of adjacent vegetal cells on mesomeres.

Mesodermal cell interactions in the sea urchin embryo: properties of skeletogenic secondary mesenchyme cells

Development ◽  
1993 ◽  
Vol 117 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
C.A. Ettensohn ◽  
S.W. Ruffins
Keyword(s):  
Sea Urchin ◽  
Pigment Cell ◽  
Cell Labeling ◽  
Pigment Cells ◽  
Cell Phenotype ◽  
Specific Cell ◽  
Mesodermal Cell ◽  
Developmental Potential ◽  
Sea Urchin Embryo ◽  
Mesenchyme Cells

An interaction between the two principal populations of mesodermal cells in the sea urchin embryo, primary and secondary mesenchyme cells (PMCs and SMCs, respectively), regulates SMC fates and the process of skeletogenesis. In the undisturbed embryo, skeletal elements are produced exclusively by PMCs. Certain SMCs also have the ability to express a skeletogenic phenotype; however, signals transmitted by the PMCs direct these cells into alternative developmental pathways. In this study, a combination of fluorescent cell-labeling methods, embryo microsurgery and cell-specific molecular markers have been used to study the lineage, numbers, normal fate(s) and developmental potential of the skeletogenic SMCs. Previous fate-mapping studies have shown that SMCs are derived from the veg2 layer of blastomeres of the 64-cell-stage embryo and from the small micromeres. By specifically labeling the small micromeres with 5-bromodeoxyuridine, we demonstrate that descendants of these cells do not participate in skeletogenesis in PMC-depleted larvae, even though they are the closest lineal relatives of PMCs. Skeletogenic SMCs are therefore derived exclusively from the veg2 blastomeres. Because the SMCs are a heterogeneous population of cells, we have sought to gain information concerning the normal fate(s) of skeletogenic SMCs by determining whether specific cell types are reduced or absent in PMC(−) larvae. Of the four known SMC derivatives: pigment cells, blastocoelar (basal) cells, muscle cells and coelomic pouch cells, only pigment cells show a major reduction (> 50%) in number following SMC skeletogenesis. We therefore propose that the PMC-derived signal regulates a developmental switch, directing SMCs to adopt a pigment cell phenotype instead of a default (skeletogenic) fate. Ablation of SMCs at the late gastrula stage does not result in the recruitment of any additional skeletogenic cells, demonstrating that, by this stage, the number of SMCs with skeletogenic potential is restricted to 60–70 cells. Previous studies showed that during their switch to a skeletogenic fate, SMCs alter their migratory behavior and cell surface properties. In this study, we demonstrate that during conversion, SMCs become insensitive to the PMC-derived signal, while at the same time they acquire PMC-specific signaling properties.

The fates of the blastomeres of the 16-cell zebrafish embryo

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1791-1798 ◽  
Author(s):  
D. Strehlow ◽  
G. Heinrich ◽  
W. Gilbert
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Probability ◽  
Zebrafish Embryo ◽  
Brachydanio Rerio ◽  
Cleavage Stage ◽  
Fate Map ◽  
Cell Stage ◽  
Fluorescent Dextran

We present a fate map for the 16-cell-stage blastomeres of the zebrafish embryo Brachydanio rerio. We injected high molecular weight fluorescent dextran into cleavage-stage cells to observe the contributions of the descendants of the first 16 cells to the adult. The patterns derived from these early cells are similar, but not identical among different embryos. Furthermore, two-color injections showed that sister blastomeres at the 16-cell stage regularly contribute to different sets of adult structures. A few of the scored tissues could not be mapped in a manner consistent with the predicted axes. Other tissues were mapped to several of the 16 blastomeres. Many of the tissues map with high probability to a few 16-cell-stage blastomeres. Thus, based on 112 injections in 56 different embryos, we have constructed a fate map by assigning probabilities for the contribution of each blastomere to each of 31 tissues in the 26-hour embryo.

scholarly journals Expression of Pigment Cell-Specific Genes in the Ontogenesis of the Sea UrchinStrongylocentrotus intermedius

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Natalya V. Ageenko ◽  
Konstantin V. Kiselev ◽  
Nelly A. Odintsova
Keyword(s):  
Gene Expression ◽  
Cell Differentiation ◽  
Sea Urchin ◽  
Polyketide Synthase ◽  
Shikimic Acid ◽  
Pigment Cell ◽  
Pigment Cells ◽  
Strongylocentrotus Intermedius ◽  
Molecular Signaling ◽  
Gastrula Stage

One of the polyketide compounds, the naphthoquinone pigment echinochrome, is synthesized in sea urchin pigment cells. We analyzed polyketide synthase (pks) and sulfotransferase (sult) gene expression in embryos and larvae of the sea urchinStrongylocentrotus intermediusfrom various stages of development and in specific tissues of the adults. We observed the highest level of expression of thepksandsultgenes at the gastrula stage. In unfertilized eggs, only trace amounts of thepksandsulttranscripts were detected, whereas no transcripts of these genes were observed in spermatozoids. The addition of shikimic acid, a precursor of naphthoquinone pigments, to zygotes and embryos increased the expression of thepksandsultgenes. Our findings, including the development of specific conditions to promote pigment cell differentiation of embryonic sea urchin cells in culture, represent a definitive study on the molecular signaling pathways that are involved in the biosynthesis of pigments during sea urchin development.

Specification of first quartet micromeres in Ilyanassa involves inherited factors and position with respect to the inducing D macromere

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 4033-4044 ◽  
Author(s):  
H.C. Sweet
Keyword(s):  
Normal Development ◽  
Eye Development ◽  
Ilyanassa Obsoleta ◽  
Cleavage Stage ◽  
Polar Lobe ◽  
Cell Stage ◽  
Cleavage Stage Embryo ◽  
Inductive Interaction ◽  
Stage Embryo ◽  
Transplantation Experiments

In the embryos of the gastropod Ilyanassa obsoleta, the development of several ectodermal structures requires an inductive interaction between the micromeres and the D macromere. The first quartet micromeres (1a, 1b, 1c and 1d) contribute to the head of the larva and descendants of 1a and 1c normally develop the eyes. The eyes do not develop if 1a and 1c are removed at the eight-cell stage. However, regulative eye development may occur if the precursors of 1a and 1c are removed at the two- or four-cell stage. One purpose of this study was to demonstrate which cells of the cleavage-stage embryo have the potential to develop an eye. The results of blastomere deletion experiments suggest that only the first quartet micromeres have this ability. In addition, the 1b micromere was found to be equivalent to 1a and 1c, but 1d was found to have a poorer eye-forming ability. A second purpose of this study was to examine how eye development is normally restricted to the 1a and 1c micromeres. Cell transplantation experiments demonstrate that the proximity of a first quartet micromere relative to the inducing D macromere is important for determining whether or not it will go on to develop an eye. The 1b micromere may not develop an eye during normal development because it is too far from the D macromere. However, the eye-forming ability of the 1d micromere is not influenced by its close position to the D macromere, but is restricted by its polar lobe lineage.

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