Disease relevance of Blastula

• In addition, continuous exposure of embryos, beginning with the hatched blastula stage, to heat killed Vibrio diazatrophicus, a marine pathogen of sea urchins, significantly increased Sp064 message content in plutei compared to unexposed controls [1].

High impact information on Blastula

• Xenopus blastula cells activate different mesodermal genes as a concentration-dependent response to activin, which behaves like a morphogen [2].
• The sqt gene is expressed in a dorsal region of the blastula that includes the extraembryonic yolk syncytial layer (YSL) [3].
• The organizer is formed in an equatorial sector of the blastula stage amphibian embryo by cells that have responded to two maternal agents: a general mesoendoderm inducer (involving the TFG-beta signaling pathway) and a dorsal modifier (probably involving the Wnt signaling pathway) [4].
• Here we conclude from the in situ analysis of blastula tissue containing activin-loaded beads that cells respond directly to changing morphogen concentrations in a way that resembles a ratchet-like process [5].
• One form of H2A and one form of H2B are synthesized only during the period from fertilization to the blastula stage [6].

Biological context of Blastula

• Strong support for the operation of a morphogen gradient mechanism in vertebrate development has come from the biochemical experiments of Green and Smith, who induced different kinds of gene expression in amphibian blastula cells exposed to small changes in activin concentration [5].
• Coincidently, early H1 genes, whose peak expression is also at the early blastula stage, all contain the same core consensus sequence (GGGCGG) [7].
• When this GC-rich sequence (GGGCTG) is converted to a perfect core Sp1 sequence (GGGCGG), the H1-beta transcripts accumulate to much greater levels and their peak accumulation is shifted to the early blastula stage rather than late blastula and gastrula stages of development [7].
• The fluorescence pattern indicates that fibronectin is found on the cell surfaces and between cells in the blastula and gastrula stages, indicating that it plays a role in cell adhesion [8].
• A nearly full-length cDNA clone (HE6) encoding the entire sequence of the hatching enzyme was isolated from a prehatching blastula lambda gt11 cDNA library [9].

Anatomical context of Blastula

• Injection of Xwnt-8 mRNA into 2-cell Xenopus embryos does not induce mesoderm formation in animal cap ectoderm isolated from these embryos at the blastula stage, but alters the response of this tissue to mesoderm induction by bFGF [10].
• In the first experiment, donor cells, previously labeled by injecting fluorescein isothiocyanate-dextran into the zygote, were isolated from blastulae; approximately 1000 of these cells were microinjected into each unlabeled recipient embryo of the same developmental stage [11].
• Maternal geminin mRNA is found throughout the animal hemisphere from oocyte through late blastula [12].
• In a second series of experiments, we studied the expression of TN mRNA and protein in combinations between animal and vegetal stage-6 blastomeres and in stage-8 blastula animal caps treated with activin A or basic fibroblastic growth factor (b-FGF) [13].
• Cyp26 is first expressed in the presumptive anterior neural ectoderm and the blastoderm margin at the late blastula [14].

Associations of Blastula with chemical compounds

• This paper documents the evidence that the large oligomeric glycoprotein complexes of unknown function first isolated as 22S particles from sea urchin embryos are the sole agents responsible for the adhesive integrity of sea urchin blastula embryos [15].
• Zygotes injected with constructs were cultured to the blastula stage in the presence of a heavy-metal chelator and then incubated in the presence or absence of cadmium [16].
• Amphibian blastulae that are treated with lithium (Li) develop into embryos that consist almost exclusively of head structures [17].
• Adenosine induces dormancy in starfish blastulae [18].
• Integrin alpha 5 is expressed at relatively high levels during cleavage, blastula and gastrula stages suggesting that it may represent the major integrin expressed in the early embryo [19].

Gene context of Blastula

• ApoE transcripts were also observed in the deep cell layer during blastula stage, in numerous ectodermal derivatives after gastrulation, and after 3 days of development in a limited number of cells both in brain and in the eyes [20].
• Cyclin D and cdk4 are required for normal development beyond the blastula stage in sea urchin embryos [21].
• Deletion of these control elements abolishes Boz-dependent repression of bmp2b in the early blastula [22].
• These data indicate that Gata5 is involved both in the generation of endodermal cells at late blastula stages and in the maintenance of endodermal sox17 expression during gastrulation [23].
• Neural induction in the absence of mesoderm: beta-catenin-dependent expression of secreted BMP antagonists at the blastula stage in Xenopus [24].

Analytical, diagnostic and therapeutic context of Blastula

• 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 [25].
• In RT-PCR analysis, the expression of dorsal gene, chordin was activated in the explants isolated after time 4.0 (about the 4000-cell stage which corresponds to the mid blastula transition (MBT)) at control stage 10 [26].
• Northern blot analysis revealed that abundant maternal FAK transcript is present in Xl eggs, with levels decreasing slightly through cleavage and early blastula stages [27].
• Three major glycan fractions of 580 kDa (g580), 150 kDa (g150), and 2 kDa (g2) were isolated and purified from Lytechinus pictus sea urchin embryos at the mesenchyme blastula stage by gel filtration and high pressure liquid chromatography [28].
• In this investigation the catecholamines dopamine, norepinephrine and epinephrine and their precursor, dopa and metabolites were determined in eight different embryonic stages of the sea urchin, Lytechinus pictus from hatched blastula to late pluteus larva, using high performance liquid chromatography with electrochemical detection [29].

References