288 results on '"McClay, David R."'
Search Results
2. Molecular Cloning of the First Metazoan β -1,3 Glucanase from Eggs of the Sea Urchin Strongylocentrotus purpuratus
- Author
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Bachman, Eric Scott and McClay, David R.
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- 1996
3. Spatial and temporal patterns of gene expression during neurogenesis in the sea urchin Lytechinus variegatus
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Slota, Leslie A., Miranda, Esther M., and McClay, David R.
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- 2019
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4. Wound repair in sea urchin larvae involves pigment cells and blastocoelar cells
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Allen, Raymond L., primary, George, Andrew N., additional, Miranda, Esther, additional, Phillips, Taji M., additional, Crawford, Janice M., additional, Kiehart, Daniel P., additional, and McClay, David R., additional
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- 2022
- Full Text
- View/download PDF
5. Specification to Biomineralization : Following a Single Cell Type as It Constructs a Skeleton
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Lyons, Deirdre C., Martik, Megan L., Saunders, Lindsay R., and McClay, David R.
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- 2014
6. Feedback circuits are numerous in embryonic gene regulatory networks and offer a stabilizing influence on evolution of those networks.
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Massri, Abdull Jesus, McDonald, Brennan, Wray, Gregory A., and McClay, David R.
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CELL differentiation ,STRONGYLOCENTROTUS purpuratus ,REGULATOR genes ,SEA urchins ,LINE drivers (Integrated circuits) ,GENE regulatory networks - Abstract
The developmental gene regulatory networks (dGRNs) of two sea urchin species, Lytechinus variegatus (Lv) and Strongylocentrotus purpuratus (Sp), have remained remarkably similar despite about 50 million years since a common ancestor. Hundreds of parallel experimental perturbations of transcription factors with similar outcomes support this conclusion. A recent scRNA-seq analysis suggested that the earliest expression of several genes within the dGRNs differs between Lv and Sp. Here, we present a careful reanalysis of the dGRNs in these two species, paying close attention to timing of first expression. We find that initial expression of genes critical for cell fate specification occurs during several compressed time periods in both species. Previously unrecognized feedback circuits are inferred from the temporally corrected dGRNs. Although many of these feedbacks differ in location within the respective GRNs, the overall number is similar between species. We identify several prominent differences in timing of first expression for key developmental regulatory genes; comparison with a third species indicates that these heterochronies likely originated in an unbiased manner with respect to embryonic cell lineage and evolutionary branch. Together, these results suggest that interactions can evolve even within highly conserved dGRNs and that feedback circuits may buffer the effects of heterochronies in the expression of key regulatory genes. [ABSTRACT FROM AUTHOR]
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- 2023
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- View/download PDF
7. Reprint of: Conditional specification of endomesoderm
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McClay, David R., primary, Croce, Jenifer C., additional, and Warner, Jacob F., additional
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- 2021
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- View/download PDF
8. EXPERIMENTS IN THE USE OF PROGRAMED MATERIALS IN TEACHING AN ELEMENTARY COLLEGE COURSE IN THE BIOLOGICAL SCIENCES. TEACHER EDUCATION RESEARCH SERIES, VOLUME 5, NUMBER 1.
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Pennsylvania State Univ., University Park. Dept. of Agricultural Education., KANTASEWI, NIPHON, and MCCLAY, DAVID R.
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THE PURPOSES OF THE STUDY WERE TO COMPARE (1) CONVENTIONAL LECTURE, PROGRAM-DISCUSSION, AND PROGRAM-PROBLEM METHODS OF INSTRUCTION, (2) STUDENT PERFORMANCE WITH AND WITHOUT CONFIDENCE IN PROGRAMED INSTRUCTION, AND (3) ACHIEVEMENT ON THE BASIS OF TEST SCORES ON THE FIRST ONE-THIRD OF THE CONVENTIONAL COURSE. TWO EXPERIMENTS WERE CONDUCTED IN INTRODUCTORY COLLEGE BACTERIOLOGY WITH A TOTAL OF 235 STUDENTS DURING 2 TERMS. IN EACH TERM, STUDENTS WERE DIVIDED INTO THREE TREATMENT GROUPS ACCORDING TO METHOD OF INSTRUCTION--(1) CONVENTIONAL, (2) PROGRAM ONLY (FIRST TERM), AND PROGRAM-PROBLEMS (SECOND TERM), AND (3) PROGRAM-DISCUSSION. FINDINGS WERE BASED ON RESULTS OF THREE TESTS GIVEN TO EACH GROUP. ANALYSIS OF COVARIANCE REVEALED NO SIGNIFICANT DIFFERENCES IN PERFORMANCE AMONG TREATMENT GROUPS. THERE WAS GREATER VARIABILITY OF SCORES WITHIN PROGRAM GROUPS THAN WITHIN CONVENTIONAL GROUPS. HIGH ACHIEVEMENT STUDENTS LEARNED BY PROGRAMED INSTRUCTION AS WELL AS STUDENTS OF LOW ACHIEVEMENT. IN THE SECOND TERM, STUDENTS WHO EXPRESSED NO CONFIDENCE IN THE PROGRAM METHOD DID SIGNIFICANTLY BETTER ON TESTS THAN THOSE WHO HAD CONFIDENCE. NO SIGNIFICANT DIFFERENCES EXISTED DURING THE FIRST TERM BETWEEN THE CONFIDENCE AND NO CONFIDENCE GROUPS. IT WAS CONCLUDED THAT PROGRAMED MATERIALS WERE AS EFFECTIVE AS CONVENTIONAL LECTURES IN TEACHING AN INTRODUCTORY COURSE IN BIOLOGICAL SCIENCES TO COLLEGE STUDENTS. (JM)
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- 1964
9. A COMPARISON OF PROGRAMED AND LECTURE-DISCUSSION METHODS OF TEACHING FARM CREDIT TO HIGH SCHOOL YOUTH AND ADULTS.
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Pennsylvania State Univ., University Park. Pennsylvania Agricultural Experiment Station., HULL, WILLIAM L., and MCCLAY, DAVID R.
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VOCATIONAL AGRICULTURE DEPARTMENTS CONSIDERED TO BE REPRESENTATIVE OF DEPARTMENTS HAVING ADULT PROGRAMS IN MARYLAND, DELAWARE, WEST VIRGINIA, PENNSYLVANIA, AND VIRGINIA WERE USED FOR THIS EXPERIMENT. PHASE ONE, IN 1961-62, WAS RANDOMLY ASSIGNED TO USE THE PROGRAMED OR THE LECTURE-DISCUSSION METHOD IN FARM CREDIT CLASSES. IN PHASE TWO (1962-63), BOTH METHODS WERE USED TO TEACH ALTERNATE CLASSES IN EIGHT SCHOOLS. A RANDOM SAMPLE WAS DRAWN FROM EACH SCHOOL FOR TEST COMPARISONS WITH EIGHT STUDENTS EACH FROM AGRICULTURE 9-10, AGRICULTURE 11-12, AND ADULT CLASSES. DATA WERE COLLECTED AND ANALYZED ON THE REMAINING STUDENTS IN EACH CLASSROOM. SOME CONCLUSIONS WERE -- (1) THE LECTURE-DISCUSSION METHOD OF TEACHING RESULTED IN SIGNIFICANTLY GREATER GAINS IN KNOWLEDGE IN PHASE ONE. SOME LECTURE-DISCUSSION TEACHERS USED TWICE AS MUCH CLASS TIME AS DID THE PROGRAMED-INSTRUCTION TEACHER, (2) WHEN THE AMOUNT OF TIME WAS CONTROLLED DURING PHASE TWO OF THE STUDY, THERE WAS NO SIGNIFICANT DIFFERENCE BETWEEN THE MEAN SCORES FOR EACH METHOD, (3) TEACHERS FELT THAT PROGRAMED INSTRUCTION SHOULD BE INTEGRATED WITH OTHER METHODS OF TEACHING, AND SOME BELIEVE THAT GOOD STUDENTS LEARNED MORE THAN POOR STUDENTS FROM THIS METHOD. (PS)
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- 1965
10. AN EVALUATION OF THE FARM LABOR SUPERVISOR TRAINING PROGRAM IN CALIFORNIA.
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California State Dept. of Education, Sacramento., California Univ., Davis., and MCCLAY, DAVID R.
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A REDUCTION OF THE FOREIGN FARM WORK FORCE IN CALIFORNIA AND SUBSEQUENT INCREASE OF THE DOMESTIC WORK FORCE CREATED A NEED FOR TRAINING FARM FOREMEN. DEVELOPMENT OF A COURSE GUIDE AND A WORKSHOP FOR TEACHERS PRECEDED THE 24 COURSES CONDUCTED TO TRAIN 420 FOREMEN WHO SUPERVISED 20,000 WORKERS. THE OBJECTIVES OF THIS STUDY WERE TO DETERMINE IF SUPERVISORY SKILL AND PRODUCTIVITY WERE INCREASED, WORKER TURNOVER WAS DECREASED, ACCIDENTS WERE REDUCED, EMPLOYERS APPROVED CONTINUATION OF COURSES, AND IMPROVEMENTS WERE NEEDED. PERSONAL INTERVIEWS WERE CONDUCTED WITH 25 RANDOMLY SELECTED FOREMEN WHO HAD ATTENDED SUPERVISORY COURSES IN 5 RANDOMLY SELECTED SCHOOLS AND THEIR EMPLOYERS. IT WAS CONCLUDED THAT FOREMEN HAD INCREASED THEIR SUPERVISORY SKILL AS A RESULT OF THE COURSE, WORKER TURNOVER DECREASED, PRODUCTIVITY INCREASED, SAFETY MAY HAVE IMPROVED, AND THAT THE COURSES SHOULD BE CONTINUED. THE REPORT OUTLINES SEVERAL RECOMMENDATIONS FOR THE STATE SUPERVISORS, TEACHER EDUCATORS, AND LOCAL TEACHERS TO FOLLOW IN IMPROVING THE PROGRAM. THE APPENDIX INCLUDES INTERVIEW SCHEDULES FOR FOREMEN AND EMPLOYERS. (JM)
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- 1966
11. Developmental single-cell transcriptomics in the Lytechinus variegatus sea urchin embryo
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Massri, Abdull J., primary, Greenstreet, Laura, additional, Afanassiev, Anton, additional, Berrio, Alejandro, additional, Wray, Gregory A., additional, Schiebinger, Geoffrey, additional, and McClay, David R., additional
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- 2021
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12. Conditional specification of endomesoderm
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McClay, David R., primary, Croce, Jenifer C., additional, and Warner, Jacob F., additional
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- 2021
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13. Intercellular Recognition: Quantitation of Initial Binding Events
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McClay, David R., Wessel, Gary M., and Marchase, Richard B.
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- 1981
14. On the Ultrastructure of Hyalin, A Cell Adhesion Protein of the Sea Urchin Embryo Extracellular Matrix
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Adelson, David L., Alliegro, Mark C., and McClay, David R.
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- 1992
15. Hedgehog Signaling Requires Motile Cilia in the Sea Urchin
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Warner, Jacob F., McCarthy, Ali M., Morris, Robert L., and McClay, David R.
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- 2014
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16. Hedgehog signaling patterns mesoderm in the sea urchin
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Walton, Katherine D., Warner, Jacob, Hertzler, Philip H., and McClay, David R.
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Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.04.018 Byline: Katherine D. Walton (a), Jacob Warner (a), Philip H. Hertzler (b), David R. McClay (a) Keywords: Hedgehog; Patched; Smoothened; Morphogenesis; Endoderm; Mesoderm; Signal transduction Abstract: The Hedgehog (Hh) signaling pathway is essential for patterning many structures in vertebrates including the nervous system, chordamesoderm, limb and endodermal organs. In the sea urchin, a basal deuterostome, Hh signaling is shown to participate in organizing the mesoderm. At gastrulation the Hh ligand is expressed by the endoderm downstream of the Brachyury and FoxA transcription factors in the endomesoderm gene regulatory network. The co-receptors Patched (Ptc) and Smoothened (Smo) are expressed by the neighboring skeletogenic and non-skeletogenic mesoderm. Perturbations of Hh, Ptc and Smo cause embryos to develop with skeletal defects and inappropriate non-skeletogenic mesoderm patterning, although initial specification of mesoderm occurs without detectable abnormalities. Perturbations of the pathway caused late defects in skeletogenesis and in the non-skeletogenic mesoderm, including altered numbers of pigment and blastocoelar cells, randomized left-right asymmetry of coelomic pouches, and disorganized circumesophageal muscle causing an inability to swallow. Together the data support the requirement of Hh signaling in patterning each of the mesoderm subtypes in the sea urchin embryo. Author Affiliation: (a) Department of Biology, Duke University, Box 90338, Durham, NC 27708, USA (b) Department of Biology, Central Michigan University, Mount Pleasant, MI 48859, USA Article History: Received 23 May 2008; Revised 30 March 2009; Accepted 17 April 2009
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- 2009
17. Twist is an essential regulator of the skeletogenic gene regulatory network in the sea urchin embryo
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Wu, Shu-Yu, Yang, Yu-Ping, and McClay, David R.
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Genetic research ,Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2008.04.003 Byline: Shu-Yu Wu, Yu-Ping Yang, David R. McClay Keywords: Twist; Mesoderm; Epithelial-mesenchymal transition; Gene regulatory network; Primary mesenchyme cell; Skeletogenesis Abstract: Recent work on the sea urchin endomesoderm gene regulatory network (GRN) offers many opportunities to study the specification and differentiation of each cell type during early development at a mechanistic level. The mesoderm lineages consist of two cell populations, primary and secondary mesenchyme cells (PMCs and SMCs). The micromere-PMC GRN governs the development of the larval skeleton, which is the exclusive fate of PMCs, and SMCs diverge into four lineages, each with its own GRN state. Here we identify a sea urchin ortholog of the Twist transcription factor, and show that it plays an essential role in the PMC GRN and later is involved in SMC formation. Perturbations of Twist either by morpholino knockdown or by overexpression result in defects in progressive phases of PMC development, including specification, ingression/EMT, differentiation and skeletogenesis. Evidence is presented that Twist expression is required for the maintenance of the PMC specification state, and a reciprocal regulation between Alx1 and Twist offers stability for the subsequent processes, such as PMC differentiation and skeletogenesis. These data illustrate the significance of regulatory state maintenance and continuous progression during cell specification, and the dynamics of the sequential events that depend on those earlier regulatory states. Author Affiliation: Department of Biology, French Family Science Center, Duke University, Durham, NC 27708, USA Article History: Received 19 September 2007; Revised 16 January 2008; Accepted 1 April 2008
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- 2008
18. Lineage-specific expansions provide genomic complexity among sea urchin GTPases
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Beane, Wendy S., Voronina, Ekaterina, Wessel, Gary M., and McClay, David R.
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Anopheles -- Physiological aspects ,Anopheles -- Analysis ,Membrane proteins -- Physiological aspects ,Membrane proteins -- Analysis ,Animal genetics -- Physiological aspects ,Animal genetics -- Analysis ,Universities and colleges -- Physiological aspects ,Universities and colleges -- Analysis ,G proteins -- Physiological aspects ,G proteins -- Analysis ,Protein biosynthesis -- Physiological aspects ,Protein biosynthesis -- Analysis ,Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2006.08.046 Byline: Wendy S. Beane (a), Ekaterina Voronina (b), Gary M. Wessel (b), David R. McClay (a) Keywords: Ras GTPase; Rho; G protein; Galpha; Dynamin; SRP; Signal recognition particle receptor; Translation; Gene duplication; Phylogenomics; Echinoderm Abstract: In every organism, GTP-binding proteins control many aspects of cell signaling. Here, we examine in silico several GTPase families from the Strongylocentrotus purpuratus genome: the monomeric Ras superfamily, the heterotrimeric G proteins, the dynamin superfamily, the SRP/SR family, and the 'protein biosynthesis' translational GTPases. Identified were 174 GTPases, of which over 90% are expressed in the embryo as shown by tiling array and expressed sequence tag data. Phylogenomic comparisons restricted to Drosophila, Ciona, and humans (protostomes, urochordates, and vertebrates, respectively) revealed both common and unique elements in the expected composition of these families. G[alpha] and dynamin families contain vertebrate expansions, consistent with whole genome duplications, whereas SRP/SR and translational GTPases are highly conserved. Unexpectedly, Ras superfamily analyses revealed several large (5+) lineage-specific expansions in the sea urchin. For Rho, Rab, Arf, and Ras subfamilies, comparing total human gene numbers to the number of sea urchin genes with vertebrate orthologs suggests reduced genomic complexity in the sea urchin. However, gene duplications in the sea urchin increase overall numbers such that total sea urchin gene numbers approximate vertebrate gene numbers for each monomeric GTPase family. These findings suggest that lineage-specific expansions may be an important component of genomic evolution in signal transduction. Author Affiliation: (a) Department of Biology, Developmental, Cell and Molecular Group, Duke University, Box 91000, Durham, NC 27708, USA (b) Department of Molecular and Cell Biology and Biochemistry, Brown University, 69 Brown Street, Providence, RI 02912, USA Article History: Received 11 May 2006; Revised 18 August 2006; Accepted 19 August 2006
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- 2006
19. Genomics and expression profiles of the Hedgehog and Notch signaling pathways in sea urchin development
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Walton, Katherine D., Croce, Jenifer C., Glenn, Thomas D., Wu, Shu-Yu, and McClay, David R.
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Genetic research ,RNA ,Cell research ,Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2006.08.064 Byline: Katherine D. Walton, Jenifer C. Croce, Thomas D. Glenn, Shu-Yu Wu, David R. McClay Keywords: Hedgehog; Notch; Endoderm; Mesoderm; Sea urchin Abstract: The Hedgehog (Hh) and Notch signal transduction pathways control a variety of developmental processes including cell fate choice, differentiation, proliferation, patterning and boundary formation. Because many components of these pathways are conserved, it was predicted and confirmed that pathway components are largely intact in the sea urchin genome. Spatial and temporal location of these pathways in the embryo, and their function in development offer added insight into their mechanistic contributions. Accordingly, all major components of both pathways were identified and annotated in the sea urchin Strongylocentrotus purpuratus genome and the embryonic expression of key components was explored. Relationships of the pathway components, and modifiers predicted from the annotation of S. purpuratus, were compared against cnidarians, arthropods, urochordates, and vertebrates. These analyses support the prediction that the pathways are highly conserved through metazoan evolution. Further, the location of these two pathways appears to be conserved among deuterostomes, and in the case of Notch at least, display similar capacities in endomesoderm gene regulatory networks. RNA expression profiles by quantitative PCR and RNA in situ hybridization reveal that Hedgehog is produced by the endoderm beginning just prior to invagination, and signals to the secondary mesenchyme-derived tissues at least until the pluteus larva stage. RNA in situ hybridization of Notch pathway members confirms that Notch functions sequentially in the vegetal-most secondary mesenchyme cells and later in the endoderm. Functional analyses in future studies will embed these pathways into the growing knowledge of gene regulatory networks that govern early specification and morphogenesis. Author Affiliation: Developmental, Cellular, and Molecular Biology Group, Duke University, Durham, NC 27710, USA Article History: Received 10 May 2006; Revised 18 August 2006; Accepted 28 August 2006
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- 2006
20. The genomic underpinnings of apoptosis in Strongylocentrotus purpuratus
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Robertson, Anthony J., Croce, Jenifer, Carbonneau, Seth, Voronina, Ekaterina, Miranda, Esther, McClay, David R., and Coffman, James A.
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Sea urchins -- Genetic aspects ,Cell death -- Analysis ,Genomes -- Analysis ,Apoptosis -- Analysis ,Biological sciences - Abstract
A study on the death of cell of sea urchins examines the proteins found in its genome.
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- 2006
21. Lineage-specific expansions provide genomic complexity among sea urchin GTPases
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Wendy S. Beane, Voronina, Ekaterina, Wessel, Gary M., and McClay, David R.
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G proteins -- Research ,Sea urchins -- Research ,Sea urchins -- Observations ,Biological sciences - Abstract
A study on cell signaling examines GTP binding proteins in the genome of sea urchin strongylocentrotus purpuratus.
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- 2006
22. A genome-wide survey of the evolutionarily conserved Wnt pathways in the sea urchin Strongylocentrotus purpuratus
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Croce, Jenifer C., Wu, Shu-Yu, Byrum, Christine, Xu, Ronghui, Duloquin, Louise, Wikramanayake, Athula H., Gache, Christian, and McClay, David R.
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Echinodermata -- Research ,Echinodermata -- Observations ,Genes -- Research ,Sea urchins -- Research ,Cladistic analysis -- Usage ,Biological sciences - Abstract
A study examines the Wnt genes present in the genome of echinoderm Strongylocentrotus purpuratus. A phylogenetic study of the proteins present in the gene of the organism is discussed.
- Published
- 2006
23. RhoA regulates initiation of invagination, but not convergent extension, during sea urchin gastrulation
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Beane, Wendy S., Gross, Jeffrey M., and McClay, David R.
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Muscle proteins -- Analysis ,Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.12.031 Byline: Wendy S. Beane (a), Jeffrey M. Gross (b), David R. McClay (a) Keywords: Sea urchin; RhoA; Gastrulation; Invagination; Convergent extension; Brachyury Abstract: During gastrulation, the archenteron is formed using cell shape changes, cell rearrangements, filopodial extensions, and convergent extension movements to elongate and shape the nascent gut tube. How these events are coordinated remains unknown, although much has been learned from careful morphological examinations and molecular perturbations. This study reports that RhoA is necessary to trigger archenteron invagination in the sea urchin embryo. Inhibition of RhoA results in a failure to initiate invagination movements, while constitutively active RhoA induces precocious invagination of the archenteron, complete with the actin rearrangements and extracellular matrix secretions that normally accompany the onset of invagination. Although RhoA activity has been reported to control convergent extension movements in vertebrate embryos, experiments herein show that RhoA activity does not regulate convergent extension movements during sea urchin gastrulation. Instead, the results support the hypothesis that RhoA serves as a trigger to initiate invagination, and once initiation occurs, RhoA activity is no longer involved in subsequent gastrulation movements. Author Affiliation: (a) Department of Biology, Developmental, Cell and Molecular Group, Duke University, PO Box 91000, Durham, NC 27708, USA (b) Molecular Cell and Developmental Biology, University of Texas at Austin, 1 University Station A6700, Austin, TX 78712, USA Article History: Received 6 October 2005; Revised 6 December 2005; Accepted 14 December 2005
- Published
- 2006
24. A Fringe-modified Notch signal affects specification of mesoderm and endoderm in the sea urchin embryo
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Peterson, Robert E. and McClay, David R.
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Endoderm -- Research ,Mesoderm -- Research ,Sea urchin embryo -- Research ,Sea urchin embryo -- Genetic aspects ,Developmental biology -- Research ,Biological sciences - Abstract
Fringe proteins are O-fucose-specific [beta]-1,3 N-acetylglucosanlinyltransferases that glycosylate the extracellular EGF repeats of Notch and enable Notch to be activated by the ligand Delta. In the sea urchin, signaling between Delta and Notch is known to be necessary for specification of secondary mesenchyme cells (SMCs). The Lytechinus variegatus Fringe homologue is expressed in both the signaling and receiving cells during this first Delta-Notch signal. Perturbation of Fringe expression through morpholino antisense oligonucleotide (MO) injection results in fewer SMCs but also causes decreased and delayed archenteron invagination. Partial endoderm specification occurs but expression of some endoderm genes is compromised. The data are consistent with a Fringe-requiting Notch signal as one upstream component of archenteron morphogenesis. Finally, Fringe perturbations result in more severe phenotypes than those previously reported for Notch dominant-negative (Lv[N.sup.neg]) injections or reported here for Notch MO (NMO) injections. Injecting a combination of Lv[N.sup.neg] and NMO results in a more severe phenotype than either treatment alone, and this combination phenocopies the fringe MO embryos. Taken together, the results show that Fringe is necessary both for maternal and zygotic Notch signals, and these Notch signals affect specification of mesoderm and endoderm. Keywords: Sea urchin; Fringe; Notch; Specification; Gastrulation; Morphogenesis; Morpholino antisense oligonucleotide
- Published
- 2005
25. LvGroucho and nuclear [beta]-catenin functionally compete for Tcf binding to influence activation of the endomesoderm gene regulatory network in the sea urchin embryo
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Range, Ryan C., Venuti, Judith M., and McClay, David R.
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Genetics -- Research ,Sea urchins -- Research ,Genetic research ,Biological sciences - Abstract
In the sea urchin embryo, specification of the endomesoderm is accomplished by the activity of a network of regulatory genes in the vegetal hemisphere, called the endomesoderm gene regulatory network (GRN). The activation of this network is mediated primarily through the activity of the Wnt pathway, though details of pathway activation remain unclear. To gain further insight into control of endomesoderm GRN activation, we have identified a sea urchin homologue of the co-repressor Groucho (LvGroucho) that has been shown to antagonize [beta]catenin/Tcf activation complexes during Wnt signaling in other systems. Groucho functions by recruiting the histone deacetylase Rpd3 to the DNA template via interaction with site-specific transcription factors, resulting in localized chromatin condensation and transcriptional silencing. Our results show that the LvGroucho protein localizes to all nuclei throughout embryonic development. Interaction assays demonstrate that LvGroucho interacts with Tcf via both the Q and the WD domains of the protein. LvGroucho interacts with Tcf to antagonize the expression of key endomesoderm regulatory genes. Assays demonstrate that LvGroucho and n[beta]-catenin functionally compete for binding to Tcf as a major mechanism by which the Tcf-control switch is regulated. Functional analysis of the N-terminal AES 197 domain of LvGroucho shows that it is sufficient to recapitulate the function of full-length LvGroucho. This finding strongly supports the conclusion that the effects of LvGro overexpression are due primarily to its interactions with Tcf and not other Groucho interacting partners, since Tcf is the only protein present in the sea urchin known to interact with AES197. Because the Q domain is unable to bind Rpd3, it was expected to behave as a dominant negative LvGroucho. Unexpectedly, overexpression of the Q domain gave functional results similar to LvGroucho and the AES197 domain. This is the first evidence for an inherent repressive function for the Q domain alone. Together, our results indicate that LvGroucho functionally competes with [beta]-catenin for Tcf binding, and this competitive mechanism regulates one of the earliest steps in the initiation of the sea urchin endomesoderm GRN. Keywords: Groucho; [beta]-catenin; Tcf; Endoderm; Mesoderm; Cell fate specification; Sea urchin
- Published
- 2005
26. SpHnf6, a transcription factor that executes multiple functions in sea urchin embryogenesis
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Otim, Ochan, Amore, Gabriele, Minokawa, Takuya, McClay, David R., and Davidson, Eric H.
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Developmental biology -- Research ,Sea urchin embryo -- Research ,Sea urchin embryo -- Genetic aspects ,Genetic transcription -- Research ,Biological sciences - Abstract
The Strongylocentrotus purpuratus hnf6 (Sphnf6) gene encodes a new member of the ONECUT family of transcription factors. The expression of hnf6 in the developing embryo is triphasic, and loss-of-function analysis shows that the Hnf6 protein is a transcription factor that has multiple distinct roles in sea urchin development, hnf6 is expressed maternally, and before gastrulation its transcripts are distributed globally. Early in development, its expression is required for the activation of PMC differentiation genes such as sm50, pm27, and msp130, but not for the activation of any known PMC regulatory genes, for example, alx, ets1, pmar1, or tbrain. Micromere transplantation experiments show that the gene is not involved in early micromere signaling. Early hnf6 expression is also required for expression of the mesodermal regulator gatac. The second known role of hnf6 is its participation after gastrulation in the oral ectoderm gene regulatory network (GRN), in which its expression is essential for the maintenance of the state of oral ectoderm specification. The third role is in the neurogenic ciliated band, which is foreshadowed exactly by a trapezoidal band of hnf6 expression at the border of the oral ectoderm and where it continues to be expressed through the end of embryogenesis. Neither oral ectoderm regulatory functions nor ciliated band formation occur normally in the absence of hnf6 expression. Keywords: Morpholino antisense oligonucleotide; Transcription factor; hnf6; ONECUT; Oral ectoderm; PMC; Sea urchin embryo
- Published
- 2004
27. Spdeadringer, a sea urchin embryo gene required separately in skeletogenic and oral ectoderm gene regulatory networks
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Amore, Gabriele, Yavrouian, Robert G., Peterson, Kevin J., Ransick, Andrew, McClay, David R., and Davidson, Eric H.
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Ectoderm -- Research ,Genetic regulation -- Research ,Genetic transcription -- Research ,Sea urchins -- Genetic aspects ,Sea urchins -- Research ,Biological sciences - Abstract
The Spdeadringer (Spdri) gene encodes an ARID-class transcription factor not previously known in sea urchin embryos. We show that Spdri is a key player in two separate developmental gene regulatory networks (GRNs). Spdri is expressed in a biphasic manner, first, after 12 h and until ingression in the skeletogenic descendants of the large micromeres; second, after about 20 h in the oral ectoderm, where its transcripts remain present at 30-50 mRNA molecules/cell far into development. In both territories, the periods of Spdri expression follow prior territorial specification events. The functional significance of each phase of expression was assessed by determining the effect of an [alpha]Spdri morpholino antisense oligonucleotide (MASO) on expression of 17 different mesodermal genes, 8 different oral ectoderm genes, and 18 other genes expressed specifically during endomesoderm specification. These effects were measured by quantitative PCR, supplemented by whole-mount in situ hybridization and morphological observations. Spdri is shown to act in the micromere descendants in the pathways that result in the expression of batteries of terminal skeletogenic genes. But, in the oral ectoderm, the same gene participates in the central GRN controlling oral ectoderm identity. Spdri is linked in the oral ectoderm GRN with several other genes encoding transcriptional regulators that are expressed specifically in various regions of the oral ectoderm. If its expression is blocked by treatment with [alpha]Spdri MASO, oral-specific features disappear and expression of the aboral ectoderm marker spec1 encompasses the whole of the ectoderm. In addition to disappearance of the oral ectoderm, morphological consequences of [alpha]Spdri MASO treatment include failure of spiculogenesis and of correct primary mesenchyme cell (pmc) patterning in the postgastrular embryo, and also failure of gastrulation. To further analyze these phenotypes, chimeric embryos were constructed consisting of two labeled micromeres combined with micromereless 4th cleavage host embryos; either the micromeres or the hosts contained [alpha]Spdri MASO. These experiments showed that, while Spdri expression is required autonomously for expression of skeletogenic genes prior to ingression, complete skeletogenesis also requires the expression of oral ectoderm patterning information. Presentation of this information on the oral side of the blastocoel in turn depends on Spdri expression in the oral ectoderm. Failure of gastrulation is not due to indirect interference with endomesodermal specification per se, since all endomesodermal genes tested function normally in [alpha]Spdri MASO embryos. Part of its cause is interference by [alpha]Spdri MASO with a late signaling function on the part of the micromere descendants that is needed to complete clearance of the Soxb1 repressor of gastrulation from the prospective endoderm, but in addition there is a nonautonomous oral ectoderm effect. Keywords: Gene regulatory network; Oral ectoderm; deadringer; Sea urchin embryo
- Published
- 2003
28. Activation of pmar1 controls specification of micromeres in the sea urchin embryo
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Oliveri, Paola, Davidson, Eric H., and McClay, David R.
- Subjects
Genetic regulation -- Research ,Genetic transcription -- Research ,Sea urchins -- Genetic aspects ,Sea urchins -- Research ,Biological sciences - Abstract
pmarl is a transcription factor in the paired class homeodomain family that was identified and found to be transcribed in micromeres beginning at the fourth cleavage of sea urchin development [Dev. Biol. 246 (2002), 209]. Based on in situ data, molecular perturbation studies, and QPCR data, the recently published gene regulatory network (GRN) model for endomesoderm specification [Science 295 (2002) 1669; Dev. Biol. 246 (2002), 162] places pmarl early in the micromere specification pathway, and upstream of two important micromere induction signals. The goal of this study was to test these three predictions of the network model. A series of embryo chimeras were produced in which pmarl activity was perturbed in one cell that was transplanted to control hosts. At the fourth cleavage, micromeres bearing altered pmarl activity were combined with a normal micromereless host embryo. If [beta]-catenin signaling is blocked, the micromeres remain unspecified and are unable to signal to the host cells. When such [beta]-catenin-blocked micromeres also express Pmarl, all observed micromere functions are rescued. The rescue includes expression of the primary mesenchyme cell (PMC) differentiation program, expression and execution of the Delta signal to induce secondary mesoderm cell (SMC) specification in macromere progeny, and expression of the early endomesoderm induction signal necessary for full specification of the endoderm. Additionally, Pmarl expressed mosaically from inserted DNA constructs causes induction of ectopic Endo 16 in adjacent cells, demonstrating further that Pmarl controls expression of the early endomesoderm induction signal. Based on these experiments, Pmarl is an important transcription factor necessary for initiating the micromere specification program and for the expression of two inductive signals produced by micromeres. Each of the tests we describe supports the placement and function of Pmarl in the endomesoderm GRN model. Keywords: Gene regulatory network; Sox; Delta; [beta]-Catenin; Paired homeodomain
- Published
- 2003
29. Primary mesenchyme cell patterning during the early stages following ingression
- Author
-
Peterson, Robert E. and McClay, David R.
- Subjects
Messenger RNA ,Stem cells ,Biological sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/S0012-1606(02)00025-8 Byline: Robert E Peterson (a), David R McClay (a) Keywords: Ingression; Epithelial to mesenchymal transition; EMT; Sea urchin; Micromere; Primary mesenchyme cells; PMC; Morphogenesis; GFP; mRNA microinjection Abstract: Sea urchin primary mesenchyme cells (PMCs) ingress into the blastocoel during an epithelial-to-mesenchymal transition (EMT), migrate along the blastocoelar wall for a period of time, and then settle into a subequatorial ring to form the larval skeleton. Fluorescent-marked blastomeres alone, or in combination with blastomere recombination, were used to track the position of PMCs during the early phases of this movement. Micromeres expressing Golgi-tethered GFP (galtase-GFP) were transplanted onto TRITC-stained hosts (in place of the endogenous micromere) to observe the progeny of a single micromere. Galtase-GFP as a Golgi marker is not transferred between PMCs when the syncytium forms. Thus, the position of cells can be followed relative to beginning position for longer periods than previously reported. The PMC progeny of a single micromere do not disperse upon ingression, but instead remain in a closely associated cluster. Generally, progeny of a single micromere remain in the quadrant of origin. In total, greater than [approximately equal to]94% of labeled PMCs remain within the local region of ingression. By contrast, when a transplanted micromere is placed at the vegetal plate after removing all 4 host micromeres, the resultant PMCs ingress and migrate into all 4 quadrants. Similarly, if 1 blastomere is injected at the 2-cell stage, and later the 2 unlabeled micromeres are removed at the 16-cell stage, the remaining PMCs ingress into all 4 quadrants of the vegetal plate. We conclude that the normal restriction of PMCs to a quadrant is due to mechanical constraint from other micromere-PMCs. If a labeled micromere is placed ectopically at the macromere/mesomere boundary, the PMC progeny ingress ectopically and migrate longitudinally along the animal-vegetal axis only. Injection of galtase-GFP into one blastomere at the 4-cell stage shows a 2-step pattern of localization. At late mesenchyme blastula and early gastrula stages, greater than 90% of GFP-expressing PMCs remain in the injected quadrant, while at mid- to late-gastrula stage and beyond, more PMCs are found outside the injected quadrant. The migration that sets up the asymmetry of the larval skeleton first occurs around mid- to late-gastrula stages, when some PMCs from an aboral quadrant migrate to the adjacent oral quadrant. In all, these data combined with previous data suggest that freshly ingressed PMCs migrate along a longitudinal path toward the animal pole and back toward the vegetal pole. Beginning at mid- to late-gastrula stage, PMCs utilize oral-aboral cues from the ectoderm for the first time. At this time, some aboral PMCs migrate into the adjacent oral quadrant to assist in the formation of the ventrolateral cluster. Author Affiliation: (a) Duke University, DCMB Group, Durham, NC 27710, USA Article History: Received 3 December 2001; Revised 16 October 2002; Accepted 23 October 2002
- Published
- 2003
30. A provisional regulatory gene network for specification of endomesoderm in the sea urchin embryo
- Author
-
Davidson, Eric H., Rast, Jonathan P., Oliveri, Paola, Ransick, Andrew, Calestani, Cristina, Yuh, Chiou-Hwa, Minokawa, Takuya, Amore, Gabriele, Hinman, Veronica, Arenas-Mena, Cesar, Otim, Ochan, Brown, C. Titus, Livi, Carolina B., Lee, Pei Yun, Revilla, Roger, Schilstra, Maria J., Clarke, Peter J.C., Rust, Alistair G., Pan, Zhengjun, Arnone, Maria I., Rowen, Lee, Cameron, R. Andrew, McClay, David R., Hood, Leroy, and Bolouri, Hamid
- Subjects
Developmental biology -- Research ,Cytochemistry -- Research ,Molecular biology -- Research ,Biological sciences - Abstract
We present the current form of a provisional DNA sequence-based regulatory gene network that explains in outline how endomesodermal specification in the sea urchin embryo is controlled. The model of the network is in a continuous process of revision and growth as new genes are added and new experimental results become available; see http://www.its.cahech.edu/~mirsky/endomeso.htm (End-mes Gene Network Update) for the latest version. The network contains over 40 genes at present, many newly uncovered in the course of this work, and most encoding DNA-binding transcriptional regulatory factors. The architecture of the network was approached initially by construction of a logic model that integrated the extensive experimental evidence now available on endomesoderm specification. The internal linkages between genes in the network have been determined functionally, by measurement of the effects of regulatory perturbations on the expression of all relevant genes in the network. Five kinds of perturbation have been applied: (1) use of morpholino antisense oligonucleotides targeted to many of the key regulatory genes in the network; (2) transformation of other regulatory factors into dominant repressors by construction of Engrailed repressor domain fusions; (3) ectopic expression of given regulatory factors, from genetic expression constructs and from injected mRNAs; (4) blockade of the [beta]-catenin/Tcf pathway by introduction of mRNA encoding the intracellular domain of cadherin; and (5) blockade of the Notch signaling pathway by introduction of mRNA encoding the extracellular domain of the Notch receptor. The network model predicts the cis-regulatory inputs that link each gene into the network. Therefore, its architecture is testable by cis-regulatory analysis. Strongylocentroms purpuratus and Lytechinus variegatus genomic BAC recombinants that include a large number of the genes in the network have been sequenced and annotated. Tests of the cis-regulatory predictions of the model are greatly facilitated by interspecific computational sequence comparison, which affords a rapid identification of likely cis-regulatory elements in advance of experimental analysis. The network specifies genomically encoded regulatory processes between early cleavage and gastrula stages. These control the specification of the micromere lineage and of the initial [veg.sub.2] endomesodermal domain; the blastula-stage separation of the central [veg.sub.2] mesodermal domain (i.e., the secondary mesenchyme progenitor field) from the peripheral [veg.sub.2] endodermal domain; the stabilization of specification state within these domains; and activation of some downstream differentiation genes. Each of the temporal--spatial phases of specification is represented in a subelement of the network model, that treats regulatory events within the relevant embryonic nuclei at particular stages. Key Words: gene network; sea urchin embryo; gene regulation.
- Published
- 2002
31. A Genomic Regulatory Network for Development. (Review)
- Author
-
Davidson, Eric H., Rast, Jonathan P., Oliveri, Paola, Ransick, Andrew, Calestani, Cristina, Yuh, Chiou-Hwa, Minokawa, Takuya, Amore, Gabriele, Hinman, Veronica, Arenas-Mena, Cesar, Otim, Ochan, Brown, C. Titus, Livi, Carolina B., Lee, Pei Yun, Revilla, Roger, Rust, Alistair G., Pan, Zheng jun, Schilstra, Maria J., Clarke, Peter J.C., Arnone, Maria I., Rowen, Lee, Cameron, R. Andrew, McClay, David R., Hood, Leroy, and Bolouri, Hamid
- Subjects
Genomics -- Research ,Developmental genetics -- Research ,Genetic regulation -- Research ,Genetic transcription -- Research ,Science and technology ,Research - Abstract
Development of the body plan is controlled by large networks of regulatory genes. A gene regulatory network that controls the specification of endoderm and mesoderm in the sea urchin embryo is summarized here. The network was derived from large-scale perturbation analyses, in combination with computational methodologies, genomic data, cis-regulatory analysis, and molecular embryology. The network contains over 40 genes at present, and each node can be directly verified at the DNA sequence level by cis-regulatory analysis. Its architecture reveals specific and general aspects of development, such as how given cells generate their ordained fates in the embryo and why the process moves inexorably forward in developmental time., The mechanism causing cats to beget cats and fish to beget fish is hardwired in the genomic DNA, because the species specificity of the body plan is the cardinal heritable [...]
- Published
- 2002
32. Chromosomal-Level Genome Assembly of the Sea Urchin Lytechinus variegatus Substantially Improves Functional Genomic Analyses
- Author
-
Davidson, Phillip L, primary, Guo, Haobing, additional, Wang, Lingyu, additional, Berrio, Alejandro, additional, Zhang, He, additional, Chang, Yue, additional, Soborowski, Andrew L, additional, McClay, David R, additional, Fan, Guangyi, additional, and Wray, Gregory A, additional
- Published
- 2020
- Full Text
- View/download PDF
33. Developmental origin of peripheral ciliary band neurons in the sea urchin embryo
- Author
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Slota, Leslie A., primary, Miranda, Esther, additional, Peskin, Brianna, additional, and McClay, David R., additional
- Published
- 2020
- Full Text
- View/download PDF
34. Ectoderm cell-ECM interaction is essential for sea urchin embryo skeletogenesis
- Author
-
Zito, Francesca, Tesoro, Valentina, McClay, David R., Nakano, Eizo, and Matranga, Valeria
- Subjects
Sea urchin embryo -- Research ,Extracellular matrix -- Research ,Ectoderm -- Research ,Morphogenesis -- Research ,Organic pigments -- Research ,Biological sciences - Abstract
Paracentrotus lividus sea urchin nectin (Pl-nectin) is an extracellular matrix (ECM) protein of the sea urchin embryo on the apical surface of the ectoderm and has been shown to be an adhesive substrate for embryonic cells. A monoclonal antibody (McAb) to Pl-nectin was generated that inhibits the adhesion of blastula cells to Pl-nectin-coated substrates in an in vitro functional assay. To examine for possible in vivo functions of Pl-nectin, Fab fragments (Fabs) of Pl-nectin McAb were added to early blastulae. Ingression of primary mesenchyme cells was not affected by Fabs. As control embryos reached the pluteus stage, treated embryos showed a severe inhibition of skeletal elongation and patterning. When the Fabs were injected directly into the blastocoel, even at higher concentration than was applied externally, skeletogenesis was normal. Therefore, the effect of the antibody on spiculogenesis was indirect. The treatment was partially reversible as embryos eventually seemed to recover and elongate spicules, although with an incorrect patterning. Migration of pigment cells was also affected by the Fabs, since they did not disperse throughout the ectoderm but remained clustered in ectopic areas. In contrast, the development of endoderm structures was not affected. Our results indicate that in the sea urchin embryo the appropriate contact of ectodermal cells with outer ECM components is essential for the correct morphogenesis of inner mesodermal structures. Key Words: sea urchin embryo; ECM protein; morphogenesis; skeletogenesis; pigment cells.
- Published
- 1998
35. A molecular analysis of hyalin - a substrate for cell adhesion in the hyaline layer of the sea urchin embryo
- Author
-
Wessel, Gary M., Berg, Linnea, Adelson, David L., Cannon, Gail, and McClay, David R.
- Subjects
Sea urchin embryo -- Analysis ,Cell adhesion -- Analysis ,Biological sciences - Abstract
The hyaline layer of echinoderm embryos is an extraembryonic matrix that functions as a substrate for cell adhesion through early development. The major constituent of the hyaline layer is the protein hyalin, a fibrillar glycoprotein of approximately 330 kDa that multimerizes in the presence of calcium. Here we provide a molecular characterization of hyalin and identify a region of the protein that is important for its function in cell adhesion. Partial hyalin cDNAs were identified from two sea urchin species, Strongylocentrotus purpuratus and Lytechinus variegatus, by screening expression libraries with monoclonal antibodies to hyalin. The cDNAs each encode a tandemly arranged series of conserved repeats averaging 84 amino acids. These hyalin repeats are as similar between the two species as they are to repeats within each species, suggesting a strong functional conservation. Analysis of this repeat shows that it is a unique sequence within the GenBank database with only weak similarity to mucoid protein sequences. The hyalin mRNA is approximately 12 kb in length and is present in developing oocytes coincident with the appearance of cortical granules, the vesicle in which the hyalin protein is specifically packaged. The mRNA is present throughout oogenesis but is rapidly lost at oocyte maturation so that eggs and early embryos have no detectable hyalin mRNA. The hyalin protein, however, remains at relatively constant levels throughout development. Thus, all the hyalin protein present during early development, when no RNA is detectable, is maternally derived and exocytosed from cortical granules at fertilization. Hyalin mRNA reaccumulates in embryos beginning at the mesenchyme blastula stage; a RNA gel blot and in situ hybridization analysis of gastrulae and larvae shows a progressive confinement of hyalin mRNA to the aboral ectoderm. Recombinant hyalin containing the tandem repeat region of the protein was expressed in bacteria and is shown to serve as an adhesive substrate, almost equal to that of native hyalin, in cell adhesion assays. This adhesive activity is partially blocked by dilute hyalin monoclonal antibody Tg-HYL to the same extent as that for native hyalin. Thus, this hyalin repeat region appears to contain the ligand for the hyalin cell surface receptor. These data help explain some of the classic functions ascribed to the hyalin protein in early development and now enable investigators to focus on the mechanisms of cell interactions with the hyaline layer. Key Words: hyalin; hyaline layer; cortical granules; fertilization; cell adhesion.
- Published
- 1998
36. Characterization of the role of cadherin in regulating cell adhesion during sea urchin development
- Author
-
Miller, Jeffrey R. and McClay, David R.
- Subjects
Cell adhesion -- Research ,Morphogenesis -- Research ,Sea urchins -- Research ,Biological sciences - Abstract
During development, the modulation of cadherin adhesive function is proposed to control various morphogenetic events including epithelial-mesenchymal conversions and tubulogenesis, although the mechanisms responsible for regulating cadherin activity during these events remain unclear. In order to gain insights into the regulation of cadherin function during morphogenesis, we utilized the sea urchin embryo as a model system to study the regulation of cadherin localization during epithelial-mesenchymal conversion and convergent-extension movements. Polyclonal antibodies raised against the cytoplasmic domain of a cloned sea urchin cadherin recognize three major polypeptides of [M.sub.r] 320, 140, and 125 kDa and specifically stain adherens junctions, and to a lesser extent, lateral membrane domains in all epithelial tissues of the embryo. Analysis of embryos during gastrulation demonstrates that changes in cadherin localization are observed in cells undergoing an epithelial-mesenchymal conversion. Ingression of primary mesenchyme cells is accompanied by the rapid loss of junctional cadherin staining and the coincident accumulation of cadherin in intracellular organelles. These data are consistent with the idea that the deadhesion of mesenchymal cells from neighboring epithelial cells involves the regulated endocytosis of cell surface cadherin molecules. Conversely, neither cadherin abundance nor localization is altered in cells of the gut which undergo convergent-extension movements during the formation of the archenteron. This observation indicates that these movements do not require the loss of junctional cadherin molecules. Instead, the necessary balance between adhesion and motility may be achieved by regulating the expression of different subtypes of cadherin molecules or modifying interactions between cadherins and catenins, proteins that bind the cytoplasmic domain of cadherin and are necessary for cadherin adhesive function. To address cadherin function at the molecular level, we used a partial cDNA representing the conserved cytoplasmic domain to identify a novel cadherin molecule in the sea urchin Lytechinus variegatus. The deduced amino acid sequence of LvG-cadherin (for Goliath-cadherin) predicts that it is a transmembrane protein with an apparent relative molecular mass of 303 kDa. The cytoplasmic domain shows significant sequence identity to that of vertebrate classic cadherins. However, the extracellular domain is distinguished from its vertebrate counterparts by both an increased number of cadherin-specific repeats and the presence of four EGF-like repeats proximal to the transmembrane domain. Taken together, these data are consistent with the hypothesis that the sea urchin possesses several cadherins, including a novel member of the cadherin family, and that the dynamic regulation of cadherin localization plays a role in epithelial to mesenchymal conversions during gastrulation. Key Words: cadherin; catenin; cell adhesion; morphogenesis; epithelial-mesenchymal conversion; convergent-extension; sea urchin.
- Published
- 1997
37. Changes in the pattern of adherens junction-assocaited beta-catenin accompany morphogenesis in the sea urchin embryo
- Author
-
Miller, Jeffrey R. and McClay, David R.
- Subjects
Genetic research -- Analysis ,Blood proteins -- Research ,Cell adhesion -- Research ,Morphogenesis -- Research ,Biological sciences - Abstract
[Beta]-Catenin was originally identified biochemically as a protein that binds E-cadherin in cultured cells and that interaction was later shown to be essential for cadherin function. Independently, armadillo, the [Beta]-catenin homolog in Drosophila melanogaster, was identified as a segment polarity gene necessary for the transduction of wingless (Wnt) signals during embryonic and larval development. Recently, several investigations have also shown that [Beta]-catenin plays a critical role in axial patterning of early Xenopus, zebrafish, and mouse embryos. In these systems, the localization of [Beta]-catenin to the plasma membrane, cytosol, and nucleus is predictive of its role in cell adhesion and signaling. In order to examine the potential role of [Beta]-catenin in regulating cell adhesion during embryogenesis, we cloned [Beta]-catenin in the sea urchin Lytechinus variegatus and characterized its subcellular distribution in cells undergoing morphogenetic movements. Indicative of a role in the establishment and maintenance of cell adhesion, [Beta]-catenin is associated with lateral cell-cell contacts and accumulates at adherens junctions from cleavage stages onward. At gastrulation, changes in junctional [Beta]-catenin localization accompany several morphogenetic events. The epithelial-mesenchymal conversion that characterizes the ingression of both primary and secondary mesenchyme cells coincides with a rapid and dramatic loss of adherens junction-associated [Beta]-catenin. In addition, epithelial cells in the archenteron display a significant decrease in adherens junction-associated [Beta]catenin levels as they undergo convergent-extension movements. These data are consistent with a role for [Beta]-catenin in regulating cell adhesion and adherens junction function during gastrulation in the sea urchin embryo. Key Words: catenin; cadherin; cell adhesion; gastrulation; morphogenesis; epithelial-mesenchymal conversion; convergent-extension; sea urchin development.
- Published
- 1997
38. Regulated exocytosis and sequential construction of the extracellular matrix surrounding the sea urchin zygote
- Author
-
Matese, John C., Black, Steven, and McClay, David R.
- Subjects
Exocytosis -- Analysis ,Sea urchin embryo -- Analysis ,Biological sciences - Published
- 1997
39. Molecular cloning of the first metazoan beta-1,3 glucanase from eggs of the sea urchin Strongylocentrotus purpuratus
- Author
-
Bachman, Eric Scott and McClay, David R.
- Subjects
Sea urchins -- Eggs ,Enzymes -- Analysis ,Science and technology - Abstract
We report the molecular cloning of the first [Beta]-1,3 glucanase from animal tissue. Three peptide sequences were obtained from [Beta]-1,3 glucanase that had been purified from eggs of the sea urchin Strongylocentrotus purpuratus and the gene was cloned by PCR using oligonucleotides deduced from the peptide sequences. The full-length cDNA shows a predicted enzyme structure of 499 aa with a hydrophobic signal sequence. A 3.2-kb message is present in eggs, during early embryogenesis, and in adult gut tissue. A polyclonal antibody to the native 68-kDa enzyme recognizes a single band during early embryogenesis that reappears in the adult gut, and recognizes a 57-kDa fusion protein made from a full-length cDNA clone for [Beta]-1,3 glucanase. The identity of this molecule as [Beta]-1,3 glucanase is confirmed by sequence homology, by the presence of all three peptide sequences in the deduced amino acid sequence, and by the recognition of the bacterial fusion protein by the antibody directed against the native enzyme. Data base searches show significant homology at the amino acid level to [Beta]-1,3 glucanases from two species of bacteria and a clotting factor from the horseshoe crab. The homology with the bacteria is centered in a 304-aa region in which there are seven scattered regions of high homology between the four divergent species. These four species were also found to have two homologous regions in common with more distantly related plant, fungal, and bacterial proteins. A global phylogeny based on these regions strongly suggests that the glucanases are a very ancient family of genes. In particular, there is an especially deep split within genes taken from the bacterial genus Bacillus.
- Published
- 1996
40. Gastrulation in the sea urchin
- Author
-
Solnica-Krezel, Lilianna, McClay, David R., Warner, Jacob, Martik, Megan, Miranda, Esther, Slota, Leslie, Solnica-Krezel, Lilianna, McClay, David R., Warner, Jacob, Martik, Megan, Miranda, Esther, and Slota, Leslie
- Abstract
Gastrulation is arguably the most important evolutionary innovation in the animal kingdom. This process provides the basic embryonic architecture, an inner layer separated from an outer layer, from which all animal forms arise. An extraordinarily simple and elegant process of gastrulation is observed in the sea urchin embryo. The cells participating in sea urchin gastrulation are specified early during cleavage. One outcome of that specification is the expression of transcription factors that control each of the many subsequent morphogenetic changes. The first of these movements is an epithelial-mesenchymal transition (EMT) of skeletogenic mesenchyme cells, then EMT of pigment cell progenitors. Shortly thereafter, invagination of the archenteron occurs. At the end of archenteron extension, a second wave of EMT occurs to release immune cells into the blastocoel and primordial germ cells that will home to the coelomic pouches. The archenteron then remodels to establish the three parts of the gut, and at the anterior end, the gut fuses with the stomodaeum to form the through-gut. As part of the anterior remodeling, mesodermal coelomic pouches bud off the lateral sides of the archenteron tip. Multiple cell biological processes conduct each of these movements and in some cases the upstream transcription factors controlling this process have been identified. Remarkably, each event seamlessly occurs at the right time to orchestrate formation of the primitive body plan. This review covers progress toward understanding many of the molecular mechanisms underlying this sequence of morphogenetic events.
- Published
- 2019
41. Neurogenesis in the sea urchin embryo is initiated uniquely in three domains
- Author
-
McClay, David R., primary, Miranda, Esther, additional, and Feinberg, Stacy L., additional
- Published
- 2018
- Full Text
- View/download PDF
42. Identification of neural transcription factors required for the differentiation of three neuronal subtypes in the sea urchin embryo
- Author
-
Slota, Leslie A., primary and McClay, David R., additional
- Published
- 2018
- Full Text
- View/download PDF
43. New insights from a high-resolution look at gastrulation in the sea urchin, Lytechinus variegatus
- Author
-
Martik, Megan L., primary and McClay, David R., additional
- Published
- 2017
- Full Text
- View/download PDF
44. Viktor Hamburger to David R. McClay, December 28, 1984
- Author
-
McClay, David R., Hamburger, Viktor, McClay, David R., and Hamburger, Viktor
- Abstract
Letter of recommendation, Correspondence
- Published
- 2016
45. David R. McClay to Viktor Hamburger, December 12, 1984
- Author
-
Hamburger, Viktor, McClay, David R., Hamburger, Viktor, and McClay, David R.
- Abstract
Letter of recommendation, Correspondence
- Published
- 2016
46. Branching out: origins of the sea urchin larval skeleton in development and evolution
- Author
-
McIntyre, Daniel C., Lyons, Deirdre C., Martik, Megan, and McClay, David R.
- Subjects
Vascular Endothelial Growth Factor A ,animal structures ,Biological Evolution ,Models, Biological ,Article ,Calcium Carbonate ,Fibroblast Growth Factors ,Wnt Proteins ,Cell Movement ,Larva ,Sea Urchins ,Ectoderm ,Animals ,Body Patterning ,Signal Transduction - Abstract
It is a challenge to understand how the information encoded in DNA is used to build a three-dimensional structure. To explore how this works the assembly of a relatively simple skeleton has been examined at multiple control levels. The skeleton of the sea urchin embryo consists of a number of calcite rods produced by 64 skeletogenic cells. The ectoderm supplies spatial cues for patterning, essentially telling the skeletogenic cells where to position themselves and providing the factors for skeletal growth. Here, we describe the information known about how this works. First the ectoderm must be patterned so that the signaling cues are released from precise positions. The skeletogenic cells respond by initiating skeletogenesis immediately beneath two regions (one on the right and the other on the left side). Growth of the skeletal rods requires additional signaling from defined ectodermal locations, and the skeletogenic cells respond to produce a membrane-bound template in which the calcite crystal grows. Important in this process are three signals, fibroblast growth factor, vascular endothelial growth factor, and Wnt5. Each is necessary for explicit tasks in skeleton production.
- Published
- 2014
47. Comparative Developmental Transcriptomics Reveals Rewiring of a Highly Conserved Gene Regulatory Network during a Major Life History Switch in the Sea Urchin Genus Heliocidaris
- Author
-
Israel, Jennifer W., primary, Martik, Megan L., additional, Byrne, Maria, additional, Raff, Elizabeth C., additional, Raff, Rudolf A., additional, McClay, David R., additional, and Wray, Gregory A., additional
- Published
- 2016
- Full Text
- View/download PDF
48. Contribution of hedgehog signaling to the establishment of left–right asymmetry in the sea urchin
- Author
-
Warner, Jacob F., primary, Miranda, Esther L., additional, and McClay, David R., additional
- Published
- 2016
- Full Text
- View/download PDF
49. Developmental gene regulatory networks in sea urchins and what we can learn from them
- Author
-
Martik, Megan L., primary, Lyons, Deirdre C., additional, and McClay, David R., additional
- Published
- 2016
- Full Text
- View/download PDF
50. Morphogenesis in sea urchin embryos: linking cellular events to gene regulatory network states
- Author
-
Lyons, Deidre, Kaltenbach, Stacy, and McClay, David R.
- Subjects
animal structures ,Osteogenesis ,Sea Urchins ,Stem Cells ,embryonic structures ,Animals ,Cell Lineage ,Gene Regulatory Networks ,Article - Abstract
Gastrulation in the sea urchin begins with ingression of the primary mesenchyme cells (PMCs) at the vegetal pole of the embryo. After entering the blastocoel the PMCs migrate, form a syncitium, and synthesize the skeleton of the embryo. Several hours after the PMCs ingress the vegetal plate buckles to initiate invagination of the archenteron. That morphogenetic process occurs in several steps. The nonskeletogenic cells produce the initial inbending of the vegetal plate. Endoderm cells then rearrange and extend the length of the gut across the blastocoel to a target near the animal pole. Finally, cells that will form part of the midgut and hindgut are added to complete gastrulation. Later, the stomodeum invaginates from the oral ectoderm and fuses with the foregut to complete the archenteron. In advance of, and during these morphogenetic events, an increasingly complex input of transcription factors controls the specification and the cell biological events that conduct the gastrulation movements.
- Published
- 2011
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