scholarly journals Cleavage modification did not alter early blastomere fates during bryozoan evolution

2016 ◽  
Author(s):  
Bruno C. Vellutini ◽  
José M. Martín-Durán ◽  
Andreas Hejnol

AbstractStereotypic cleavage patterns play a crucial role in cell fate determination by precisely positioning early embryonic blastomeres. Although misplaced cell divisions can alter blastomere fates and cause embryonic defects, cleavage patterns have changed several times during animal evolution. Here, we analyze the evolutionary transition from spiral cleavage – a stereotypic pattern remarkably conserved in many protostomes – to the biradial cleavage of bryozoans. We characterize the cell lineage, MAPK signaling and expression of several developmental genes in the bryozoanMembranipora membranacea, and found that the fate and the genes expressed in the early bryozoan blastomeres are similar to their putative homologous blastomeres in spiral-cleaving embryos. The data indicate that cleavage geometry evolved independent from other developmental traits during the transition from spiral to biradial cleavage in the bryozoan lineage, revealing that stereotypic cleavage patterns can be evolutionarily modified without major changes to the molecular identity and fate of embryonic blastomeres.

Blood ◽  
2008 ◽  
Vol 112 (7) ◽  
pp. 2969-2972 ◽  
Author(s):  
J. Tristan Dobson ◽  
Jake Seibert ◽  
Evelyn M. Teh ◽  
Sahar Da'as ◽  
Robert B. Fraser ◽  
...  

Abstract Mast cells (MCs) play critical roles in allergy and inflammation, yet their development remains controversial due to limitations posed by traditional animal models. The zebrafish provides a highly efficient system for studying vertebrate hematopoiesis. We have identified zebrafish MCs in the gill and intestine, which resemble their mammalian counterparts both structurally and functionally. Carboxypeptidase A5 (cpa5), a MC-specific enzyme, is expressed in zebrafish blood cells beginning at 24 hours post fertilization (hpf). At 28 hpf, colocalization is observed with pu.1, mpo, l-plastin, and lysozyme C, but not fms or cepbα, identifying these early MCs as a distinct myeloid population arising from a common granulocyte/monocyte progenitor. Morpholino “knock-down” studies demonstrate that transcription factors gata-2 and pu.1, but not gata-1 or fog-1, are necessary for early MC development. These studies validate the zebrafish as an in vivo tool for studying MC ontogeny and function with future capacity for modeling human MC diseases.


Author(s):  
Francesca Pagani ◽  
Elisa Tratta ◽  
Patrizia Dell’Era ◽  
Manuela Cominelli ◽  
Pietro Luigi Poliani

AbstractEarly B-cell factor-1 (EBF1) is a transcription factor with an important role in cell lineage specification and commitment during the early stage of cell maturation. Originally described during B-cell maturation, EBF1 was subsequently identified as a crucial molecule for proper cell fate commitment of mesenchymal stem cells into adipocytes, osteoblasts and muscle cells. In vessels, EBF1 expression and function have never been documented. Our data indicate that EBF1 is highly expressed in peri-endothelial cells in both tumor vessels and in physiological conditions. Immunohistochemistry, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and fluorescence-activated cell sorting (FACS) analysis suggest that EBF1-expressing peri-endothelial cells represent bona fide pericytes and selectively express well-recognized markers employed in the identification of the pericyte phenotype (SMA, PDGFRβ, CD146, NG2). This observation was also confirmed in vitro in human placenta-derived pericytes and in human brain vascular pericytes (HBVP). Of note, in accord with the key role of EBF1 in the cell lineage commitment of mesenchymal stem cells, EBF1-silenced HBVP cells showed a significant reduction in PDGFRβ and CD146, but not CD90, a marker mostly associated with a prominent mesenchymal phenotype. Moreover, the expression levels of VEGF, angiopoietin-1, NG2 and TGF-β, cytokines produced by pericytes during angiogenesis and linked to their differentiation and activation, were also significantly reduced. Overall, the data suggest a functional role of EBF1 in the cell fate commitment toward the pericyte phenotype.


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