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.
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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 Article
The electron microscopy and cytochemistry of oogenesis and the cytochemistry of embryonic development of the prosobranch gastropod Bembicium nanum L.
TL;DR: Both technical procedures have been employed, in an attempt to examine nuclear and nucleolar structure and interrelationships, nucleocytoplasmic relationships and changes in cytopLasmic complexity during oogenesis and vitellogenesis of Bembicium nanum.
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Fishing Pluripotency Mechanisms In Vivo
TL;DR: The many experimental advantages of fish will fuel rapid analysis of the roles of pluripotency factors in fish embryonic development and the identification of new molecules and mechanisms governing pluripOTency.
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Insights into the development of Notocotylus attenuatus (Digenea: Notocotylidae) in Lymnaea stagnalis: from mother sporocyst to cercariae
TL;DR: Experimental infections of Lymnaea stagnalis using N. attenuatus eggs resulted in the development of sporocysts containing one germ ball or mother redia within the hepatopancreas and the intricate nature of larval transitions within its snail host is highlighted.
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The Balbiani Body in the Female Germline Cells of an Earwig, Opisthocosmia silvestris
TL;DR: In forficuloid earwigs, female germ cell cysts are composed of two cells only: the pro-oocte and pro-nurse cells, and it is shown that in Opisthocosmia silvestris, the Cystoblast, as well as both cells of the cyst, contain the Balbiani body, a distinct cytoplasmic organelle composed of numerous mitochondria.
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The role of HIRA and maternal histones in sperm nucleus decondensation in the gibel carp and color crucian carp.
TL;DR: The results suggest that HIRA may be a critical factor required for sperm nucleus decondensation, while the defect in deposition of some maternal histones in the sperm nucleus could be one reason why heterologous sperm cannot decondense in the gibel carp egg.
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