Structural changes of the chromatin in early development of sea urchins

AbstractDevelopmental gene regulatory networks (GRNs) are assemblages of gene regulatory interactions that direct ontogeny of animal body plans. Studies of GRNs operating in early development of euechinoid sea urchins has revealed that little appreciable change has occurred since their divergence approximately 90 million years ago (mya). These observations suggest that strong conservation of GRN architecture has been maintained in early development of the sea urchin lineage. To test whether this is true for all sea urchins, comparative analyses of echinoid taxa that diverged deeper in geological time must be conducted. Recent studies highlighted extensive divergence of skeletogenic mesoderm specification in the sister clade of euechinoids, the cidaroids, suggesting that comparative analyses of cidaroid GRN architecture may confer a greater understanding of the evolutionary dynamics of developmental GRNs. Here, we report spatiotemporal patterning of 55 regulatory genes and perturbation analyses of key regulatory genes involved in euechinoid oral-aboral patterning of non-skeletogenic mesodermal and ectodermal domains in early development of the cidaroid Eucidaris tribuloides. Our results indicate that developmental GRNs directing mesodermal and ectodermal specification have undergone marked alterations since the divergence of cidaroids and euechinoids. Notably, statistical and clustering analyses of echinoid temporal gene expression datasets indicate that regulation of mesodermal genes has diverged more markedly than regulation of ectodermal genes. Although research on indirect-developing euechinoid sea urchins suggests strong conservation of GRN circuitry during early embryogenesis, this study indicates that since the divergence of cidaroids and euechinoids developmental GRNs have undergone significant divergence.

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Counterproductive transcriptional and translational regulation of elongation factor 1-α synthesis during early development in sea urchins

Developmental Biology ◽

10.1016/0012-1606(90)90371-o ◽

1990 ◽

Vol 142 (2) ◽

pp. 486-488 ◽

Cited By ~ 7

Author(s):

Margaret Truschel Peeler ◽

Leslie Kelso-Winemiller ◽

Ming-Fan Wu ◽

James K. Skipper ◽

Matthew M. Winkler

Keyword(s):

Early Development ◽

Translational Regulation ◽

Sea Urchins ◽

Elongation Factor ◽

Elongation Factor 1 ◽

Transcriptional And Translational Regulation

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Example: Early Pattern Formation in Amphibia

Morphogenesis and Evolution ◽

10.1093/oso/9780195049121.003.0007 ◽

1988 ◽

Author(s):

Keith Stewart Thomson

Keyword(s):

Pattern Formation ◽

Early Development ◽

Sea Urchins ◽

Vitelline Membrane ◽

Causal Processes ◽

Phases Of Development ◽

Primary Induction ◽

The Subject ◽

Axis Of Symmetry ◽

Early Phases

The Amphibia has been one of the most important animal groups for the study of developmental biology, and a huge descriptive and experimental literature has accumulated over the years. While sea urchins, molluscs, and nematodes, and more recently, Drosophila, have each become an important vehicle for the study of different aspects of development, the Amphibia and chordates in general have been especially important as the vehicle for the study of inductive regulative mechanisms. The early development of all chordates is marked by two revolutions in the control of early pattern formation: dorsalization at the blastula stage and gastrulation—primary induction caused by the “organizer” —which was studied in great detail in Amphibia by Spemann and his coworkers and continues to be the subject of intense scrutiny. The early phases of development in Amphibia exemplify rather well some of the problems in discovering the causal processes in development, whether in the egg, at fertilization, in the blastula, or in gastrulation itself. The short discussion of early development in Amphibia that follows is meant to exemplify rather than catalogue these questions. The oocyte in amphibians is radially symmetrical. A first axis of symmetry is established between a more heavily pigmented animal hemisphere and a less pigmented vegetal hemisphere. Before fertilization the egg is covered with a transparent vitelline membrane. When fertilization occurs, the vitelline membrane lifts from the surface of the egg and the egg is then free to rotate inside it so that the animal hemisphere lies uppermost and the vegetal hemisphere is lowermost. This rotation is apparently a response to gravity, which means that the vegetal hemisphere is heavier, almost certainly a result of the concentration of more and larger yolk granules in the vegetal hemisphere. Therefore, if the egg rotates to a new orientation with the yolk down and the animal hemisphere up, it must be the case that at this point the yolk and other egg contents are not free to be redistributed within the egg but are secured in place. The animal vegetal axis now marks the future anteroposterior axis of the embryo.

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Inhibitory effects of odor substances, geosmin and 2-methylisoborneol, on early development of sea urchins

Water Research ◽

10.1016/0043-1354(96)00104-2 ◽

1996 ◽

Vol 30 (10) ◽

pp. 2508-2511 ◽

Cited By ~ 21

Author(s):

Mutsuyasu Nakajima ◽

Takahiro Ogura ◽

Yoshiyuki Kusama ◽

Noriyuki Iwabuchi ◽

Taichi Imawaka ◽

...

Keyword(s):

Early Development ◽

Sea Urchins ◽

Inhibitory Effects

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Early development of congeneric sea urchins (Heliocidaris) with contrasting life history modes in a warming and high CO2 ocean

Marine Environmental Research ◽

10.1016/j.marenvres.2014.07.007 ◽

2014 ◽

Vol 102 ◽

pp. 78-87 ◽

Cited By ~ 23

Author(s):

Natasha A. Hardy ◽

Maria Byrne

Keyword(s):

Life History ◽

Early Development ◽

Sea Urchins ◽

High Co2

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Characterization of RNA species synthesized during early development of sea urchins

Journal of Molecular Biology ◽

10.1016/s0022-2836(65)80240-6 ◽

1965 ◽

Vol 14 (1) ◽

pp. 195-213 ◽

Cited By ~ 55

Author(s):

Donald G. Comb ◽

Solomon Katz ◽

Richard Branda ◽

Charles J. Pinzino

Keyword(s):

Early Development ◽

Sea Urchins

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Evolution of abbreviated development in Heliocidaris erythrogramma dramatically re-wired the highly conserved sea urchin developmental gene regulatory network to decouple signaling center function from ultimate fate

10.1101/712216 ◽

2019 ◽

Author(s):

Allison Edgar ◽

Maria Byrne ◽

David R. McClay ◽

Gregory A. Wray

Keyword(s):

Early Development ◽

Regulatory Networks ◽

Molecular Mechanisms ◽

Sea Urchins ◽

Stabilizing Selection ◽

Developmental Gene ◽

Heliocidaris Erythrogramma ◽

Signaling Center ◽

Gene Regulatory ◽

Ultimate Fate

AbstractDevelopmental gene regulatory networks (GRNs) describe the interactions among gene products that drive the differential transcriptional and cell regulatory states that pattern the embryo and specify distinct cell fates. GRNs are often deeply conserved, but whether this is the product of constraint inherent to the network structure or stabilizing selection remains unclear. We have constructed the first formal GRN for early development in Heliocidaris erythrogramma, a species with dramatically accelerated, direct development. This life history switch has important ecological consequences, arose rapidly, and has evolved independently many times in echinoderms, suggesting it is a product of selection. We find that H. erythrogramma exhibits dramatic differences in GRN topology compared with ancestral, indirect-developing sea urchins. In particular, the GRN sub-circuit that directs the early and autonomous commitment of skeletogenic cell precursors in indirect developers appears to be absent in H. erythrogramma, a particularly striking change in relation to both the prior conservation of this sub-circuit and the key role that these cells play ancestrally in early development as the embryonic signaling center. These results show that even highly conserved molecular mechanisms of early development can be substantially reconfigured in a relatively short evolutionary time span, suggesting that selection rather than constraint is responsible for the striking conservation of the GRN among other sea urchins.

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The Spindle Assembly Checkpoint Functions during Early Development in Non-Chordate Embryos

Cells ◽

10.3390/cells9051087 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1087

Author(s):

Janet Chenevert ◽

Marianne Roca ◽

Lydia Besnardeau ◽

Antonella Ruggiero ◽

Dalileh Nabi ◽

...

Keyword(s):

Early Development ◽

Spindle Assembly Checkpoint ◽

Sea Urchins ◽

Volume Ratio ◽

Spindle Assembly ◽

Mitotic Progression ◽

Checkpoint Response ◽

Ascidian Embryos ◽

Spindle Microtubules ◽

Prolonged Delay

In eukaryotic cells, a spindle assembly checkpoint (SAC) ensures accurate chromosome segregation, by monitoring proper attachment of chromosomes to spindle microtubules and delaying mitotic progression if connections are erroneous or absent. The SAC is thought to be relaxed during early embryonic development. Here, we evaluate the checkpoint response to lack of kinetochore-spindle microtubule interactions in early embryos of diverse animal species. Our analysis shows that there are two classes of embryos, either proficient or deficient for SAC activation during cleavage. Sea urchins, mussels, and jellyfish embryos show a prolonged delay in mitotic progression in the absence of spindle microtubules from the first cleavage division, while ascidian and amphioxus embryos, like those of Xenopus and zebrafish, continue mitotic cycling without delay. SAC competence during early development shows no correlation with cell size, chromosome number, or kinetochore to cell volume ratio. We show that SAC proteins Mad1, Mad2, and Mps1 lack the ability to recognize unattached kinetochores in ascidian embryos, indicating that SAC signaling is not diluted but rather actively silenced during early chordate development.

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