On the role of gravity and positional information in embryological axis formation and tissue compartmentalization

1991 ◽  
Vol 39 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Wilfried Allaerts
Keyword(s):  
Positional Information ◽  
Axis Formation

oto is a homeotic locus with a role in anteroposterior development that is partially redundant with Lim1

Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 5085-5095 ◽  
Author(s):  
J.S. Zoltewicz ◽  
N.W. Plummer ◽  
M.I. Lin ◽  
A.S. Peterson
Keyword(s):  
Critical Role ◽  
Positional Information ◽  
Axial Skeleton ◽  
Branchial Arch ◽  
Chromosome 1 ◽  
Axis Formation ◽  
Head Development ◽  
Optic Vesicles ◽  
Dose Dependent

Genetic control of mammalian head development involves mechanisms that are shared with trunk development as well as mechanisms that are independent. For example, mutations in the nodal gene disrupt axis formation and head development while mutations in the Otx2 or Lim1 genes block head development without disrupting development of the trunk. We show here that the oto mutation on mouse chromosome 1 defines a locus with a critical role in anterior development. The oto mutation disrupts development of the telencephalic and optic vesicles, the pharyngeal endoderm and the first branchial arch. Also, oto embryos have dose-dependent, posterior homeotic transformations throughout the axial skeleton. To further dissect the role of the oto locus in head development, we crossed mice carrying oto and Lim1 mutations. Interactions between the two mutations indicate that the role of oto in the regulation of head development is partially redundant with that of Lim1. The phenotype of oto embryos points to an early and critical role for oto in the development of forebrain subregions. Transformations of the vertebrae in oto embryos reveal a Lim1-independent role in the establishment of positional information in the trunk.

Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos

2020 ◽  
Vol 48 (3) ◽  
pp. 1243-1253 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Cell Cortex ◽  
Axis Formation ◽  
Aurora A Kinase ◽  
Aurora A ◽  
C Elegans ◽  
Cell Embryo ◽  
Polarity Establishment

Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior–posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.

scholarly journals Dissecting the role of Fgf signaling during gastrulation and left-right axis formation in mouse embryos using chemical inhibitors

2010 ◽  
Vol 239 (6) ◽  
pp. 1768-1778 ◽  
Author(s):  
Shinya Oki ◽  
Keiko Kitajima ◽  
Chikara Meno
Keyword(s):  
Mouse Embryos ◽  
Axis Formation ◽  
Fgf Signaling ◽  
Chemical Inhibitors

scholarly journals Successive specification of Drosophila neuroblasts NB 6-4 and NB 7-3 depends on interaction of the segment polarity genes wingless, gooseberry and naked cuticle

Development ◽  
2001 ◽  
Vol 128 (17) ◽  
pp. 3253-3261 ◽  
Author(s):  
Nirupama Deshpande ◽  
Rainer Dittrich ◽  
Gerhard M. Technau ◽  
Joachim Urban
Keyword(s):  
Cell Fate ◽  
Cell Lineage ◽  
Positional Information ◽  
Dorsoventral Patterning ◽  
Expression Domain ◽  
Direct Role ◽  
Segment Polarity Genes ◽  
Segment Polarity ◽  
Unique Identity

The Drosophila central nervous system derives from neural precursor cells, the neuroblasts (NBs), which are born from the neuroectoderm by the process of delamination. Each NB has a unique identity, which is revealed by the production of a characteristic cell lineage and a specific set of molecular markers it expresses. These NBs delaminate at different but reproducible time points during neurogenesis (S1-S5) and it has been shown for early delaminating NBs (S1/S2) that their identities depend on positional information conferred by segment polarity genes and dorsoventral patterning genes. We have studied mechanisms leading to the fate specification of a set of late delaminating neuroblasts, NB 6-4 and NB 7-3, both of which arise from the engrailed (en) expression domain, with NB 6-4 delaminating first. In contrast to former reports, we did not find any evidence for a direct role of hedgehog in the process of NB 7-3 specification. Instead, we present evidence to show that the interplay of the segmentation genes naked cuticle (nkd) and gooseberry (gsb), both of which are targets of wingless (wg) activity, leads to differential commitment to NB 6-4 and NB 7-3 cell fate. In the absence of either nkd or gsb, one NB fate is replaced by the other. However, the temporal sequence of delamination is maintained, suggesting that formation and specification of these two NBs are under independent control.

scholarly journals Role of the RGS (regulator of G protein signaling) domain of Axin in vertebrate axis formation

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Patricia Schneider ◽  
Diane Slusarski ◽  
Douglas Houston
Keyword(s):  
G Protein ◽  
Axis Formation ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Signaling Domain

The IP3 receptor/Ca2+ channel and its cellular function

2007 ◽  
Vol 74 ◽  
pp. 9-22 ◽  
Author(s):  
Katsuhiko Mikoshiba
Keyword(s):  
Exocrine Secretion ◽  
Axis Formation ◽  
Ip3 Receptor ◽  
Release Channel ◽  
Saliva Secretion ◽  
Binding Core ◽  
Gastric Juice Secretion ◽  
Trisphosphate Receptor ◽  
Type 3

The IP3R [IP3 (inositol 1,4,5-trisphosphate) receptor] is responsible for Ca2+ release from the ER (endoplasmic reticulum). We have been working extensively on the P400 protein, which is deficient in Purkinje-neuron-degenerating mutant mice. We have discovered that P400 is an IP3R and we have determined the primary sequence. Purified IP3R, when incorporated into a lipid bilayer, works as a Ca2+ release channel and overexpression of IP3R shows enhanced IP3 binding and channel activity. Addition of an antibody blocks Ca2+ oscillations indicating that IP3R1 works as a Ca2+ oscillator. Studies on the role of IP3R during development show that IP3R is involved in fertilization and is essential for determination of dorso-ventral axis formation. We found that IP3R is involved in neuronal plasticity. A double homozygous mutant of IP3R2 (IP3R type 2) and IP3R3 (IP3R type 3) shows a deficit of saliva secretion and gastric juice secretion suggesting that IP3Rs are essential for exocrine secretion. IP3R has various unique properties: cryo-EM (electron microscopy) studies show that IP3R contains multiple cavities; IP3R allosterically and dynamically changes its form reversibly (square form–windmill form); IP3R is functional even though it is fragmented by proteases into several pieces; the ER forms a meshwork but also forms vesicular ER and moves along microtubules using a kinesin motor; X ray analysis of the crystal structure of the IP3 binding core consists of an N-terminal β-trefoil domain and a C-terminal α-helical domain. We have discovered ERp44 as a redox sensor in the ER which binds to the luminal part of IP3R1 and regulates its activity. We have also found the role of IP3 is not only to release Ca2+ but also to release IRBIT which binds to the IP3 binding core of IP3R.

scholarly journals Nodal signalling in Xenopus : the role of Xnr5 in left/right asymmetry and heart development

Open Biology ◽  
2016 ◽  
Vol 6 (8) ◽  
pp. 150187 ◽  
Author(s):  
Emmanuel Tadjuidje ◽  
Matthew Kofron ◽  
Adnan Mir ◽  
Christopher Wylie ◽  
Janet Heasman ◽  
...  
Keyword(s):  
Heart Development ◽  
Cardiac Troponin ◽  
Axis Formation ◽  
Mrna Levels ◽  
Blastula Stage ◽  
Signalling Molecules ◽  
Tailbud Stage ◽  
Heart Field ◽  
Left Right Asymmetry

Nodal class TGF-β signalling molecules play essential roles in establishing the vertebrate body plan. In all vertebrates, nodal family members have specific waves of expression required for tissue specification and axis formation. In Xenopus laevis , six nodal genes are expressed before gastrulation, raising the question of whether they have specific roles or act redundantly with each other. Here, we examine the role of Xnr5. We find it acts at the late blastula stage as a mesoderm inducer and repressor of ectodermal gene expression, a role it shares with Vg1. However, unlike Vg1, Xnr5 depletion reduces the expression of the nodal family member xnr1 at the gastrula stage. It is also required for left/right laterality by controlling the expression of the laterality genes xnr1, antivin ( lefty ) and pitx2 at the tailbud stage. In Xnr5-depleted embryos, the heart field is established normally, but symmetrical reduction in Xnr5 levels causes a severely stunted midline heart, first evidenced by a reduction in cardiac troponin mRNA levels, while left-sided reduction leads to randomization of the left/right axis. This work identifies Xnr5 as the earliest step in the signalling pathway establishing normal heart laterality in Xenopus .

scholarly journals Loss of positional information when tracking multiple moving dots: The role of visual memory

2009 ◽  
Vol 49 (1) ◽  
pp. 10-27 ◽  
Author(s):  
Sathyasri Narasimhan ◽  
Srimant P. Tripathy ◽  
Brendan T. Barrett
Keyword(s):  
Visual Memory ◽  
Positional Information

scholarly journals Apparent role of Tribolium orthodenticle in anteroposterior blastoderm patterning largely reflects novel functions in dorsoventral axis formation and cell survival

Development ◽  
2010 ◽  
Vol 137 (11) ◽  
pp. 1853-1862 ◽  
Author(s):  
K. Kotkamp ◽  
M. Klingler ◽  
M. Schoppmeier
Keyword(s):  
Cell Survival ◽  
Axis Formation ◽  
Dorsoventral Axis
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