Anteroposterior patterning in the zebrafish, Danio rerio: an explant assay reveals inductive and suppressive cell interactions

Development ◽  
1996 ◽  
Vol 122 (6) ◽  
pp. 1873-1883 ◽  
Author(s):  
C.G. Sagerstrom ◽  
Y. Grinblat ◽  
H. Sive
Keyword(s):  
Danio Rerio ◽  
Neural Induction ◽  
Active Role ◽  
Cell Number ◽  
Type I ◽  
Animal Pole ◽  
Anteroposterior Patterning ◽  
Embryonic Shield ◽  
Low Levels ◽  
Neural Markers

We report the first extended culture system for analysing zebrafish (Danio rerio) embryogenesis with which we demonstrate neural induction and anteroposterior patterning. Explants from the animal pole region of blastula embryos ('animal caps') survived for at least two days and increased in cell number. Mesodermal and neural-specific genes were not expressed in cultured animal caps, although low levels of the dorsoanterior marker otx2 were seen. In contrast, we observed strong expression of gta3, a ventral marker and cyt1, a novel type I cytokeratin expressed in the outer enveloping layer. Isolated ‘embryonic shield’, that corresponds to the amphibian organizer and amniote node, went on to express the mesodermal genes gsc and ntl, otx2, the anterior neural marker pax6, and posterior neural markers eng3 and krx20. The expression of these genes defined a precise anteroposterior axis in shield explants. When conjugated to animal caps, the shield frequently induced expression of anterior neural markers. More posterior markers were rarely induced, suggesting that anterior and posterior neural induction are separable events. Mesodermal genes were also seldom activated in animal caps by the shield, demonstrating that neural induction did not require co-induction of mesoderm in the caps. Strikingly, ventral marginal zone explants suppressed the low levels of otx2 in animal caps, indicating that ventral tissues may play an active role in axial patterning. These data suggest that anteroposterior patterning in the zebrafish is a multi-step process.

The Genetic Defect of Type I von Willebrand Disease “Vicenza” Is Linked to the von Willebrand Factor Gene

1993 ◽  
Vol 69 (02) ◽  
pp. 173-176 ◽  
Author(s):  
Anna M Randi ◽  
Elisabetta Sacchi ◽  
Gian Carlo Castaman ◽  
Francesco Rodeghiero ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Von Willebrand Factor ◽  
Autosomal Dominant ◽  
Genetic Defect ◽  
Von Willebrand Disease ◽  
Type I ◽  
Bleeding Tendency ◽  
Factor Gene ◽  
Low Levels ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryType I von Willebrand disease (vWD) Vicenza is a rare variant with autosomal dominant transmission, characterized by the presence of supranormal von Willebrand factor (vWF) multimers in plasma, similar to those normally found in endothelial cells and megakaryocytes. The patients have very low levels of plasma vWF contrasting with a mild bleeding tendency. The pathophysiology of this subtype is still unknown. The presence of supranormal multimers in the patients’ plasma could be due to a mutation in the vWF molecule which affects post-translational processing, or to a defect in the cells’ processing machinery, independent of the vWF molecule. In order to determne if type I vWD Vicenza is linked to the vWF gene, we studied six polymorphic systems identified within the vWF gene in two apparently unrelated families with type I vWD Vicenza. The results of this study indicate a linkage between vWF gene and the type I vWD Vicenza trait. This strongly suggests that type I vWD Vicenza is due to a mutation in one of the vWF alleles, which results in an abnormal vWF molecule that is processed to a lesser extent than normal vWF.

Neural induction and the structure of the target cell surface

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 171-187
Author(s):  
A. M. Duprat ◽  
L. Gualandris ◽  
P. Rouge
Keyword(s):  
Cell Surface ◽  
Structural Integrity ◽  
Neural Induction ◽  
Active Role ◽  
Target Cells ◽  
Similar Treatment ◽  
Structural Modifications ◽  
Pleurodeles Waltl

Lectins (SBA and PSA) were used to provoke crowding and structural modifications of the presumptive ectoderm cell surface in order to investigate the role of the membrane organization of the competent target cells in neural induction. Are specific characteristics of the cell surface essential for this phenomenon to occur? From amphibian gastrulae, it is possible to obtain neural induction in vitro by association of presumptive ectoderm (target cells) with chordamesoderm (inductor tissue): 4 h of contact is sufficient in Pleurodeles waltl for transmission of the inductive signal. Very quickly, the treatment of the normal ectoderm by lectins (SBA-FITC or PSA-FITC) provoked surface modifications. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm did not result in any neural induction. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm previous to its association with the natural inductor for 4 h, disturbed the phenomenon: no induction. Similar treatment followed by association with the inductor for 24 h: induction. Treatment of SBA or PSA with their respective hapten inhibitors prior to addition to ectodermal cells completely blocked the suppressive effects on induction. The structural integrity of the membrane of competent target cells is necessary for neural induction to occur. The cell membrane could thus play, directly or indirectly, an active role in the specificity of this process

scholarly journals Differential bioactivity of four BMP-family members as function of biomaterial stiffness

2021 ◽  
Author(s):  
Adrià Sales ◽  
Valia Khodr ◽  
Paul Machillot ◽  
Laure Fourel ◽  
Amaris Guevara-Garcia ◽  
...  
Keyword(s):  
Cellular Response ◽  
Cell Spreading ◽  
Cell Number ◽  
Type I ◽  
Dependent Manner ◽  
Bone Differentiation ◽  
Bmp Receptors ◽  
Smad Phosphorylation ◽  
Matrix Bound ◽  
Automated Screening

ABSTRACTWhereas soft biomaterial is not able to induce cell spreading, BMP-2 presented by a soft film has been described to be sufficient to trigger cell spreading, migration and downstream BMP-2 signaling. Based on thin polyelectrolyte films of controlled stiffness, we investigated whether the presentation of four BMP members (2, 4, 7, 9) in a matrix-bound manner may differentially impact cell adhesion and bone differentiation of skeletal progenitors. We performed high content and automated screening of cellular responses, including cell number, cell spreading area, SMAD phosphorylation and alkaline phosphatase activity. The basolateral presentation of the different BMPs allowed us to discriminate the specificity of cellular response and the role of BMP receptors type I, type II, as well as three β integrins, in a BMP type and stiffness-dependent manner.

Abstract 628: Hepatic Insulin Signaling Regulates ApoA-I Gene Expression Through the Type I Deiodinase.

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Jing Liu ◽  
Antonio Hernandez-Ono ◽  
Valerie Galton ◽  
Henry Ginsberg
Keyword(s):  
Insulin Signaling ◽  
Knockout Mice ◽  
Hepg2 Cells ◽  
Density Lipoprotein ◽  
Type I ◽  
Mrna Levels ◽  
Reverse T3 ◽  
Hepatic Insulin Signaling ◽  
Low Levels

People with low levels of high density lipoprotein cholesterol (HDLC) and apolipoprotein A-I (ApoA-I) have a higher risk of cardiovascular disease. Low levels of HDLC are common in individuals who are insulin resistant (IR), e.g., with metabolic syndrome and type 2 diabetes mellitus (T2DM). Despite the high prevalence of these two disorders, very little work has been reported regarding the molecular pathways linking insulin signaling or action and the levels of either HDLC or ApoA-1. We reported previously that liver specific insulin receptor (InsR) knockout mice (LIRKO) have markedly reduced plasma HDLC levels that increase after restoration of hepatic Akt signaling. In the present study, we created acute LIRKO mice by injecting an albumin-Cre adenovirus (Ad) into InsR floxed mice and observed marked reductions in HDLC, the expression of ApoA-I, and the expression of the gene coding Type1 iodothyronine deiodinase1, a selenoenzyme expressed highly in the liver that converts thyroxine to 3,5,3’-triiodothyronine (T3) or reverse T3. Deiodinase 1 knockout mice also had significantly reduced hepatic ApoA-I mRNA levels. Overexpression of Dio1 in LIRKO restored HDLC and significantly increased the expression of ApoA-I mRNA. In vitro studies showed that the expression of ApoA-I was significantly reduced after knockdown of either InsR or Dio1 expression in HepG2 cells. Moreover, overexpression of Dio1 restored ApoA-I promoter activity that had been decreased by knockdown of InsR. Deletion analysis of ApoAI promoter regions showed that insulin signaling regulated ApoA-I expression by acting on a region which does not contain any thyroid response elements. Pulse-chase experiments in HepG2 cells showed that deficiency of insulin signaling resulted in decreased synthesis and secretion of ApoAI. Our results indicates that defective hepatic insulin signaling results in reduced expression of Dio1 which, in turn, leads to reduced expression of ApoA-I and decreased synthesis and secretion of ApoA-I from hepatocytes. We believe our studies have defined a novel pathway from insulin signaling to ApoA-I synthesis that may lead to new approaches for increasing HDL levels in people with defective insulin signaling.

Patterning of the neural ectoderm of Xenopus laevis by the amino-terminal product of hedgehog autoproteolytic cleavage

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2349-2360 ◽  
Author(s):  
C.J. Lai ◽  
S.C. Ekker ◽  
P.A. Beachy ◽  
R.T. Moon
Keyword(s):  
Gene Family ◽  
Neural Induction ◽  
Neural Tissue ◽  
Internal Deletion ◽  
Anteroposterior Patterning ◽  
Amino Terminal ◽  
Neural Genes ◽  
Neural Ectoderm ◽  
Amino Terminal Domain ◽  
Autoproteolytic Cleavage

The patterns of embryonic expression and the activities of Xenopus members of the hedgehog gene family are suggestive of role in neural induction and patterning. We report that these hedgehog polypeptides undergo autoproteolytic cleavage. Injection into embryos of mRNAs encoding Xenopus banded-hedgehog (X-bhh) or the amino-terminal domain (N) demonstrates that the direct inductive activities of X-bhh are encoded by N. In addition, both N and X-bhh pattern neural tissue by elevating expression of anterior neural genes. Unexpectedly, an internal deletion of X-bhh (delta N-C) was found to block the activity of X-bhh and N in explants and to reduce dorsoanterior structures in embryos. As elevated hedgehog activity increases the expression of anterior neural genes, and as delta N-C reduces dorsoanterior structures, these complementary data support a role for hedgehog in neural induction and anteroposterior patterning.

Micromere fate maps in leech embryos: lineage-specific differences in rates of cell proliferation

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3427-3438 ◽  
Author(s):  
C. M. Smith ◽  
D. A. Weisblat
Keyword(s):  
Cell Proliferation ◽  
Late Stage ◽  
Squamous Epithelium ◽  
Cell Lineage ◽  
Cell Number ◽  
Animal Pole ◽  
Fluorescent Cell ◽  
Plate Formation

Stereotyped early cleavages in glossiphoniid leech embryos yield 25 micromeres, along with 3 macromeres and 10 teloblasts. The micromeres generate prostomial tissues and also give rise to most of the squamous epithelium of a provisional integument that spreads epibolically from the animal pole, covering the rest of the embryo during germinal plate formation. We systematically injected individual micromeres with fluorescent cell lineage tracers at the time of their birth and quantitatively mapped the contributions of all these cells to the late stage 7 embryo, a time in development that is early in the epibolic expansion. At this time, micromere derivatives comprise two types of cells: squamous epithelial (superficial) cells that cover the germinal bands and the region of the animal cap between the germinal bands; and underlying (deep) cells that are confined to the distal ends of the germinal bands and in the area between their distal ends. We find that individual micromeres contribute clones of deep and/or superficial progeny that are stereotyped with respect to both numbers and types of cells in the clone and the domains that they occupy. The N teloblasts also contribute cells to the squamous epithelium. We find significant differences in the rate of cell proliferation between different micromere clones. These differences appear to reflect lineage-specific traits, since there is little or no regulation of cell number after ablation of individual micromeres.

The effect of crop size and low levels of major elements on fruit characteristics and incidence of storage pit in Sturmer apples in pot experiments

1964 ◽  
Vol 4 (14) ◽  
pp. 260 ◽  
Author(s):  
D Martin ◽  
GC Wade ◽  
JM Rolls
Keyword(s):  
Cell Number ◽  
Major Elements ◽  
Mineral Elements ◽  
Physiological Effect ◽  
Sand Culture ◽  
Protein Nitrogen ◽  
Pot Experiments ◽  
Complete Treatment ◽  
Low Levels ◽  
Carry Over

Pot experiments in sand culture with Sturmer apple trees were continued to study the effects of low levels of major elements on the storage type of bitter pit. Compared with a complete treatment, the no calcium treatment induced high susceptibility to storage pit but had no other significant effects. The other treatments had no effect on pit. Pitted fruits had a lower calcium and higher protein nitrogen content than sound fruits but there was no evidence that the level of other mineral elements was affected. Other fruit responses to low level treatment are discussed. No nitrogen and no phosphorus prevented fruit set but no magnesium and no potassium increased it. However, many of the effects on fruit cell number and levels of mineral elements in fruits may be due to competition between the fruits for limited resources rather than any direct physiological effect. Differences between years in fruit responses may be due to alternate cropping with differences in carry over of reserves or differences in level of competition between fruit and vegetative growth and caution is necessary in interpreting results.

scholarly journals Effect of Type I Antifreeze Proteins on the Freezing and Melting Processes of Cryoprotective Solutions Studied by Site-Directed Spin Labeling Technique

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 352 ◽  
Author(s):  
Adiel F. Perez ◽  
Kyle R. Taing ◽  
Justin C. Quon ◽  
Antonia Flores ◽  
Yong Ba
Keyword(s):  
Freezing Point ◽  
Antifreeze Proteins ◽  
Active Role ◽  
Spin Labeling ◽  
Ice Crystals ◽  
Freezing Injury ◽  
Type I ◽  
Paramagnetic Resonance ◽  
Potential Applications ◽  
Site Directed Spin Labeling

Antifreeze proteins (AFPs) protect organisms living in subzero environments from freezing injury, which render them potential applications for cryopreservation of living cells, organs, and tissues. Cryoprotective agents (CPAs), such as glycerol and propylene glycol, have been used as ingredients to treat cellular tissues and organs to prevent ice crystal’s formation at low temperatures. To assess AFP’s function in CPA solutions, we have the applied site-directed spin labeling technique to a Type I AFP. A two-step process to prevent bulk freezing of the CPA solutions was observed by the cryo-photo microscopy, i.e., (1) thermodynamic freezing point depression by the CPAs; and (2) inhibition to the growth of seed ice crystals by the AFP. Electron paramagnetic resonance (EPR) experiments were also carried out from room temperature to 97 K, and vice versa. The EPR results indicate that the spin labeled AFP bound to ice surfaces, and inhibit the growths of ice through the bulk freezing processes in the CPA solutions. The ice-surface bound AFP in the frozen matrices could also prevent the formation of large ice crystals during the melting processes of the solutions. Our study illustrates that AFPs can play an active role in CPA solutions for cryopreservation applications.

The effect of maternal thyroidectomy prior to conception on foetal brain development in sheep

1986 ◽  
Vol 112 (1) ◽  
pp. 93-99 ◽  
Author(s):  
B.J. Potter ◽  
G. H. McIntosh ◽  
M. T. Mano ◽  
P. A. Baghurst ◽  
J. Chavadej ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Maternal Plasma ◽  
Cell Number ◽  
The Body ◽  
Neonatal Brain ◽  
Foetal Brain ◽  
Body Weights ◽  
Low Levels ◽  
Maternal Thyroid ◽  
The Brain

Abstract. Merino ewes were surgically thyroidectomized, and mated 6 weeks later when their plasma thyroxine (T4) levels were negligible. Their foetuses were delivered by hysterotomy at 52, 71, 84, 98, 125, 140 days gestation or at term (150 days). Despite the very low levels of T4 in maternal plasma, the concentrations of T4 in foetal plasma were not significantly different after 71 days gestation from those of foetuses of sham-operated (control) ewes. Foetal brain and body weights, however, were reduced from 71 days compared to those of foetuses of sham-operated ewes. The foetal brain weights but not the body weights were restored to normal from 125 days to term. In additon to the weights, cell number (DNA) and cell size (protein:DNA ratio) appeared to be normal in the neonatal brain at parturition and this was confirmed by histological examination of the brains. Thus lack of maternal thyroid hormones in early pregnancy may cause a reduction in brain and body growth in the foetus which, in the case of the brain, appears to be restored to normal after the onset of foetal thyroid function.

Sign in / Sign up

Export Citation Format

Share Document