scholarly journals Patterning of the embryo: the first spatial decisions in the life of a mouse

Development ◽  
2002 ◽  
Vol 129 (4) ◽  
pp. 815-829 ◽  
Author(s):  
Magdalena Zernicka-Goetz
Keyword(s):  
Mouse Embryo ◽  
Molecular Mechanisms ◽  
Blastocyst Stage ◽  
The Body ◽  
Axis Formation ◽  
Visceral Endoderm ◽  
Spatial Cues ◽  
Mouse Development ◽  
Animal Pole ◽  
Embryonic Polarity

Although in most species the polarity of the embryo takes its roots from the spatial patterning of the egg, mammals were viewed as an exception. This was because the anteroposterior polarity of the mouse embryo could not be seen until gastrulation, and no developmental cues were known that could define polarity at earlier stages. Why should we now re-consider this view? While mechanisms of axis formation in mammals could, in principle, be unique, the evolutionary conservation of numerous other developmental processes raises the question of why mammals would have evolved a different way or timing of organising their embryonic polarity. Indeed, recent evidence shows that well before the onset of gastrulation, the mouse embryo initiates asymmetric patterns of gene expression in its visceral endoderm. Although this extra-embryonic tissue does not contribute to the body itself, it is involved in axis formation. Other recent work has revealed that spatial distribution of cells in the visceral endoderm can be traced back to polarity present at the blastocyst stage. These insights have raised the possibility that embryonic polarity might also originate early during development of mammalian embryos. Indeed it now appears that there are at least two spatial cues that operate in the mouse egg to shape polarity of the blastocyst. One of these is at the animal pole, which is defined by the site of female meiosis, and another is associated with the position of sperm entry. In this review I discuss these recent findings, which have led to the recognition that mouse embryos initiate development of their polarity at the earliest stages of their life. This novel perspective raises questions about the nature of cellular and molecular mechanisms that could convert developmental cues in the zygote to axes of the blastocyst, and hence into polarity of the post-implantation embryo. It also brings to light the need to understand how such mechanisms could enable early mouse development to be so regulative.

The Foxh1-dependent autoregulatory enhancer controls the level of Nodal signals in the mouse embryo

Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3455-3468 ◽  
Author(s):  
Dominic P. Norris ◽  
Jane Brennan ◽  
Elizabeth K. Bikoff ◽  
Elizabeth J. Robertson
Keyword(s):  
Mouse Embryo ◽  
Late Onset ◽  
Axis Formation ◽  
Visceral Endoderm ◽  
Mouse Development ◽  
Developmental Abnormalities ◽  
Intronic Enhancer ◽  
Vertebrate Embryo ◽  
Early Mouse ◽  
Pitx2 Expression

The TGFβ-related growth factor Nodal governs anteroposterior (AP) and left-right (LR) axis formation in the vertebrate embryo. A conserved intronic enhancer (ASE), containing binding sites for the fork head transcription factor Foxh1, modulates dynamic patterns of Nodal expression during early mouse development. This enhancer is responsible for early activation of Nodal expression in the epiblast and visceral endoderm, and at later stages governs asymmetric expression during LR axis formation. We demonstrate ASE activity is strictly Foxh1 dependent. Loss of this autoregulatory enhancer eliminates transcription in the visceral endoderm and decreases Nodal expression in the epiblast, but causes surprisingly discrete developmental abnormalities. Thus lowering the level of Nodal signaling in the epiblast disrupts both orientation of the AP axis and specification of the definitive endoderm. Targeted removal of the ASE also dramatically reduces left-sided Nodal expression, but the early events controlling LR axis specification are correctly initiated. However loss of the ASE disrupts Lefty2 (Leftb) expression and causes delayed Pitx2 expression leading to late onset, relatively minor LR patterning defects. The feedback loop is thus essential for maintenance of Nodal signals that selectively regulate target gene expression in a temporally and spatially controlled fashion in the mouse embryo.

HNF3beta and Lim1 interact in the visceral endoderm to regulate primitive streak formation and anterior-posterior polarity in the mouse embryo

Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4499-4511 ◽  
Author(s):  
A. Perea-Gomez ◽  
W. Shawlot ◽  
H. Sasaki ◽  
R.R. Behringer ◽  
S. Ang
Keyword(s):  
Mouse Embryo ◽  
Primitive Streak ◽  
Axis Formation ◽  
Visceral Endoderm ◽  
Primary Defect ◽  
Homozygous Mutant ◽  
Early Mouse ◽  
Mesoderm Patterning ◽  
Anterior Posterior ◽  
Anterior Visceral Endoderm

Recent embryological and genetic experiments have suggested that the anterior visceral endoderm and the anterior primitive streak of the early mouse gastrula function as head- and trunk-organising centers, respectively. Here, we report that HNF3beta and Lim1 are coexpressed in both organising centers suggesting synergistic roles of these genes in regulating organiser functions and hence axis development in the mouse embryo. To investigate this possibility, we generated compound HNF3beta and Lim1 mutant embryos. An enlarged primitive streak and a lack of axis formation were observed in HNF3beta (−)(/)(−);Lim1(−)(/)(−), but not in single homozygous mutant embryos. Chimera experiments indicate that the primary defect in these double homozygous mutants is due to loss of activity of HNF3beta and Lim1 in the visceral endoderm. Altogether, these data provide evidence that these genes function synergistically to regulate organiser activity of the anterior visceral endoderm. Moreover, HNF3beta (−)(/)(−);Lim1(−)(/)(−) mutant embryos also exhibit defects in mesoderm patterning that are likely due to lack of specification of anterior primitive streak cells.

Hex: a homeobox gene revealing peri-implantation asymmetry in the mouse embryo and an early transient marker of endothelial cell precursors

Development ◽  
1998 ◽  
Vol 125 (1) ◽  
pp. 85-94 ◽  
Author(s):  
P.Q. Thomas ◽  
A. Brown ◽  
R.S. Beddington
Keyword(s):  
Endothelial Cell ◽  
Mouse Embryo ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Definitive Endoderm ◽  
Visceral Endoderm ◽  
Primitive Endoderm ◽  
Mouse Development ◽  
Expression Domain ◽  
Early Marker

The divergent homeobox gene Hex exhibits three notable expression patterns during early mouse development. Initially Hex is expressed in the primitive endoderm of the implanting blastocyst but by 5.5 dpc its transcripts are present only in a small patch of visceral endoderm at the distal tip of the egg cylinder. Lineage analysis shows that these cells move unilaterally to assume an anterior position while continuing to express Hex. The primitive streak forms on the opposite side of the egg cylinder from this anterior Hex expression domain approximately 24 hours after the initial anterior movement of the distal visceral endoderm. Thus, Hex expression marks the earliest unequivocal molecular anteroposterior asymmetry in the mouse embryo and indicates that the anteroposterior axis of the embryo develops from conversion of a proximodistal asymmetry established in the primitive endoderm lineage. Subsequently, Hex is expressed in the earliest definitive endoderm to emerge from the streak and its expression within the gut strongly suggests that the ventral foregut is derived from the most anterior definitive endoderm and that the liver is probably the most anterior gut derivative. Hex is also an early marker of the thyroid primordium. Within the mesoderm, Hex is transiently expressed in the nascent blood islands of the visceral yolk sac and later in embryonic angioblasts and endocardium. Comparison with flk-1 (T. P. Yamaguchi et al., Development 118, 489–498, 1993) expression indicates that Hex is also an early marker of endothelial precursors but its expression in this progenitor population is much more transient than that of flk-1, being downregulated once endothelial cell differentiation commences.

Cell-matrix interactions in the early mouse embryo

1992 ◽  
Vol 50 (1) ◽  
pp. 600-601
Author(s):  
A.E. Sutherland ◽  
P.G. Calarco ◽  
C.H. Damsky
Keyword(s):  
Mouse Embryo ◽  
Giant Cells ◽  
Blastocyst Stage ◽  
Integrin Subunit ◽  
Β1 Integrin ◽  
Cell Stage ◽  
Early Mouse Embryo ◽  
Migratory Activity ◽  
Early Mouse ◽  
Cell Matrix Interactions

Cell-extracellular matrix (ECM) interactions mediated by the integrin family of receptors are critical for morphogenesis and may also play a regulatory role in differentiation during early development. We have examined the onset of expression of individual integrin subunit proteins in the early mouse embryo, and their roles in early morphogenetic events. As detected by immunoprecipitation, the α6, αV, β1, and β3 subunits are detected as early as the 4-cell stage, α5 at the hatched blastocyst stage and αl and α3 following blastocyst attachment. We tested the role of these integrins in the attachment and migratory activity of two cell populations of the early mouse embryo: the trophoblast giant cells, which invade the uterine stroma and ultimately contribute to the chorio-allantoic placenta, and the parietal endoderm, which migrates over the inner surface of the trophoblast and ultimately forms Reichert's membrane and the parietal yolk sac. Experiments were done in serum-free medium on substrates coated with laminin (Ln) and fibronectin (Fn). Trophoblast outgrowth occurs on Ln and its E8 fragment (long arm), but not on the E1’ fragment (cross region) (Figs. 1, 2 ). This outgrowth is inhibited by anti-E8, anti-Ln, and by the anti-β1 family antiserum anti-ECMR, but not by anti-αV or the function-perturbing GoH3 antibody that recognizes the α6/β1 integrin, a major Ln (E8) receptor. This suggests that trophoblast outgrowth on Ln or E8 is mediated by a different β1 integrin such as α3/β1. Early stages of trophoblast outgrowth (up to 48 hours) on Fn are inhibited by anti-Fn and by function-perturbing anti-αV antibodies, whereas at later times outgrowth becomes insensitive to anti-αV but remains sensitive to the anti-β1 family antiserum anti-ECMr, indicating that trophoblast cells modulate their interaction with Fn during outgrowth. Trophoblast outgrowth on vitronectin (Vn) is sensitive to anti-αV antibodies throughout the 5-day period examined.

Toxicology

2017 ◽  
Author(s):  
Robert Laumbach ◽  
Michael Gochfeld
Keyword(s):  
Molecular Mechanisms ◽  
Molecular Targets ◽  
Toxicity Testing ◽  
The Body ◽  
Toxic Substances ◽  
Basic Principles ◽  
Practical Applications ◽  
Mechanisms Of Toxicity ◽  
Body Distribution ◽  
Threshold Doses

This chapter describes the basic principles of toxicology and their application to occupational and environmental health. Topics covered include pathways that toxic substances may take from sources in the environment to molecular targets in the cells of the body where toxic effects occur. These pathways include routes of exposure, absorption into the body, distribution to organs and tissues, metabolism, storage, and excretion. The various types of toxicological endpoints are discussed, along with the concepts of dose-response relationships, threshold doses, and the basis of interindividual differences and interspecies differences in response to exposure to toxic substances. The diversity of cellular and molecular mechanisms of toxicity, including enzyme induction and inhibition, oxidative stress, mutagenesis, carcinogenesis, and teratogenesis, are discussed and the chapter concludes with examples of practical applications in clinical evaluation and in toxicity testing.

scholarly journals Expression patterns of signalling molecules and transcription factors in the early rabbit embryo and their significance for modelling amniote axis formation

2021 ◽  
Author(s):  
Ruben Plöger ◽  
Christoph Viebahn
Keyword(s):  
Transcription Factors ◽  
Expression Patterns ◽  
In Situ Hybridisation ◽  
Body Plan ◽  
The Body ◽  
Anchor Point ◽  
Axis Formation ◽  
Point Model ◽  
Signalling Molecules ◽  
Rabbit Embryo

AbstractThe anterior-posterior axis is a central element of the body plan and, during amniote gastrulation, forms through several transient domains with specific morphogenetic activities. In the chick, experimentally proven activity of signalling molecules and transcription factors lead to the concept of a ‘global positioning system’ for initial axis formation whereas in the (mammotypical) rabbit embryo, a series of morphological or molecular domains are part of a putative ‘three-anchor-point model’. Because circular expression patterns of genes involved in axis formation exist in both amniote groups prior to, and during, gastrulation and may thus be suited to reconcile these models, the expression patterns of selected genes known in the chick, namely the ones coding for the transcription factors eomes and tbx6, the signalling molecule wnt3 and the wnt inhibitor pkdcc, were analysed in the rabbit embryonic disc using in situ hybridisation and placing emphasis on their germ layer location. Peripheral wnt3 and eomes expression in all layers is found initially to be complementary to central pkdcc expression in the hypoblast during early axis formation. Pkdcc then appears — together with a posterior-anterior gradient in wnt3 and eomes domains — in the epiblast posteriorly before the emerging primitive streak is marked by pkdcc and tbx6 at its anterior and posterior extremities, respectively. Conserved circular expression patterns deduced from some of this data may point to shared mechanisms in amniote axis formation while the reshaping of localised gene expression patterns is discussed as part of the ‘three-anchor-point model’ for establishing the mammalian body plan.

scholarly journals Insights into how environment shapes post-mortem RNA transcription in mouse brain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raphael Severino Bonadio ◽  
Larissa Barbosa Nunes ◽  
Patricia Natália S. Moretti ◽  
Juliana Forte Mazzeu ◽  
Stefano Cagnin ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Mouse Brain ◽  
Molecular Mechanisms ◽  
Cell Communication ◽  
Rna Degradation ◽  
The Body ◽  
Biological Processes ◽  
Post Mortem ◽  
Gene Expression Alterations ◽  
Upregulated Genes

AbstractMost biological features that occur on the body after death were already deciphered by traditional medicine. However, the molecular mechanisms triggered in the cellular microenvironment are not fully comprehended yet. Previous studies reported gene expression alterations in the post-mortem condition, but little is known about how the environment could influence RNA degradation and transcriptional regulation. In this work, we analysed the transcriptome of mouse brain after death under three concealment simulations (air exposed, buried, and submerged). Our analyses identified 2,103 genes differentially expressed in all tested groups 48 h after death. Moreover, we identified 111 commonly upregulated and 497 commonly downregulated genes in mice from the concealment simulations. The gene functions shared by the individuals from the tested environments were associated with RNA homeostasis, inflammation, developmental processes, cell communication, cell proliferation, and lipid metabolism. Regarding the altered biological processes, we identified that the macroautophagy process was enriched in the upregulated genes and lipid metabolism was enriched in the downregulated genes. On the other hand, we also described a list of biomarkers associated with the submerged and buried groups, indicating that these environments can influence the post-mortem RNA abundance in its particular way.

scholarly journals Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Hamed Nosrati ◽  
Reza Aramideh Khouy ◽  
Ali Nosrati ◽  
Mohammad Khodaei ◽  
Mehdi Banitalebi-Dehkordi ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Wound Healing ◽  
Tissue Regeneration ◽  
Molecular Mechanisms ◽  
Healing Process ◽  
The Body ◽  
Key Factors ◽  
Potential Applications ◽  
Nanocomposite Scaffolds

AbstractSkin is the body’s first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

scholarly journals Mangiferin as New Potential Anti-Cancer Agent and Mangiferin-Integrated Polymer Systems—A Novel Research Direction

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 79
Author(s):  
Svetlana N. Morozkina ◽  
Thi Hong Nhung Vu ◽  
Yuliya E. Generalova ◽  
Petr P. Snetkov ◽  
Mayya V. Uspenskaya
Keyword(s):  
Molecular Mechanisms ◽  
Biological Activities ◽  
Research Direction ◽  
Biological Action ◽  
The Body ◽  
Biologically Active ◽  
Polymer Systems ◽  
Anti Cancer ◽  
Long Time ◽  
Cancer Agent

For a long time, the pharmaceutical industry focused on natural biologically active molecules due to their unique properties, availability and significantly less side-effects. Mangiferin is a naturally occurring C-glucosylxantone that has substantial potential for the treatment of various diseases thanks to its numerous biological activities. Many research studies have proven that mangiferin possesses antioxidant, anti-infection, anti-cancer, anti-diabetic, cardiovascular, neuroprotective properties and it also increases immunity. It is especially important that it has no toxicity. However, mangiferin is not being currently applied to clinical use because its oral bioavailability as well as its absorption in the body are too low. To improve the solubility, enhance the biological action and bioavailability, mangiferin integrated polymer systems have been developed. In this paper, we review molecular mechanisms of anti-cancer action as well as a number of designed polymer-mangiferin systems. Taking together, mangiferin is a very promising anti-cancer molecule with excellent properties and the absence of toxicity.

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