Growing an Embryo from a Single Cell: A Hurdle in Animal Life
TLDR
In mammals and in endoparasites, development in a nutritive environment releases the growth constraint, but growth of cells before gastrulation requires a new program to sustain pluripotency during this growth.Abstract:
A requirement that an animal be able to feed to grow constrains how a cell can grow into an animal, and it forces an alternation between growth (increase in mass) and proliferation (increase in cell number). A growth-only phase that transforms a stem cell of ordinary proportions into a huge cell, the oocyte, requires dramatic adaptations to help a nucleus direct a 10(5)-fold expansion of cytoplasmic volume. Proliferation without growth transforms the huge egg into an embryo while still accommodating an impotent nucleus overwhelmed by the voluminous cytoplasm. This growth program characterizes animals that deposit their eggs externally, but it is changed in mammals and in endoparasites. In these organisms, development in a nutritive environment releases the growth constraint, but growth of cells before gastrulation requires a new program to sustain pluripotency during this growth.read more
Citations
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Nothing in Biology Makes Sense Except in the Light of Evolution
TL;DR: The theory that biological species are descended from common ancestors provides an indispensable heuristic to understand why living organisms are what they are and do what they do.
Journal ArticleDOI
Expression of engrailed proteins in arthropods, annelids and chordates
TL;DR: A monoclonal antibody is described that recognizes a conserved epitope in the homeodomain of engrailed proteins of a number of different arthropods, annelids, and chordates; this antibody is used to isolate the grasshopperEngrailed gene, a homeobox gene that has an important role in Drosophila segmentation.
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Zygotic Genome Activation in Vertebrates.
TL;DR: Progress in understanding vertebrate ZGA dynamics in frogs, fish, mice, and humans is reviewed to explore differences and emphasize common features.
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Waves of Cdk1 Activity in S Phase Synchronize the Cell Cycle in Drosophila Embryos
TL;DR: In Drosophila embryos, Cdk1 positive feedback serves primarily to ensure the rapid onset of mitosis, while wave propagation is regulated by S phase events, demonstrating a fundamental distinction between S phase Cdk 1 waves, which propagate as active trigger waves in an excitable medium, and mitotic Cdk2 waves, who propagate as passive phase waves.
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Capturing Totipotent Stem Cells
TL;DR: The biological and molecular characterization of cultured cells with developmental potential similar to totipotent blastomeres are reviewed, and recent progress toward the capture and stabilization of the totip powerless state in vitro is assessed.
References
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Journal ArticleDOI
Cyclin: A protein specified by maternal mRNA in sea urchin eggs that is destroyed at each cleavage division
TL;DR: Eggs of the sea urchin Lytechinus pictus and oocytes of the surf clam Spisula solidissima also contain proteins that only start to be made after fertilization and are destroyed at certain points in the cell division cycle, and it is proposed to call these proteins the cyclins.
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Embryonic stem cells.
Helen J. Rippon,Anne E. Bishop +1 more
TL;DR: This work reviews the history of murine and human ES cell Lines, including practical and ethical aspects of ES cell isolation from pre‐implantation embryos, maintenance of undifferentiated ES cell lines in the cell culture environment, and differentiation of ES cells in vitro and in vivo into mature somatic cell types.
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A major developmental transition in early Xenopus embryos: II. Control of the onset of transcription.
TL;DR: It is shown here that a plasmid containing a cloned gene coding for a yeast leucine tRNA comes under developmental control when injected into cleaving eggs, suggesting that the MBT is triggered by the DNA through titration of suppressor components present in the egg.
Nothing in Biology Makes Sense Except in the Light of Evolution
TL;DR: The theory that biological species are descended from common ancestors provides an indispensable heuristic to understand why living organisms are what they are and do what they do.
Journal ArticleDOI
Expression of engrailed proteins in arthropods, annelids, and chordates
Nipam H. Patel,Enrique Martin-Blanco,Kevin G. Coleman,Stephen J. Poole,Michael C. Ellis,Thomas B. Kornberg,Corey S. Goodman +6 more
TL;DR: It is suggested that engrailed is a gene whose ancestral function was in neurogenesis and whose function was co-opted during the evolution of segmentation in the arthropods, but not in the annelids and chordates.
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