Changes in the expression of the carbohydrate epitope HNK-1 associated with mesoderm induction in the chick embryo

Development ◽  
1988 ◽  
Vol 104 (4) ◽  
pp. 643-655 ◽  
Author(s):  
D.R. Canning ◽  
C.D. Stern

We report that a monoclonal antibody, HNK-1, identifies specific regions and cell types during primitive streak formation in the chick blastoderm. Immunohistochemical studies show that the cells of the forming hypoblast are HNK-1 positive from the earliest time at which they can be identified. Some cells of the margin of the blastoderm are also positive. The mesoderm cells of the primitive streak stain strongly with the antibody from the time of their initial appearance. In the epiblast, some cells are positive and some negative at pre-primitive-streak stages, but as the primitive streak develops a gradient of staining intensity is seen within the upper layer, increasing towards the primitive streak. At later stages of development, the notochord and the mesenchyme of the headfold are positive, while the rest of the mesoderm (lateral plate) no longer expresses HNK-1 immunoreactivity. This antibody therefore reveals changes associated with mesodermal induction: before induction, it recognizes the ‘inducing’ tissue (the hypoblast) and reveals a mosaic pattern in the responding tissue (the epiblast); after primitive streak formation, the mesoderm of the primitive streak that results from the inductive interactions expresses the epitope strongly. Affinity purification of HNK-1-related proteins in various tissues was carried out, followed by SDS-PAGE to identify them. The hypoblast, mesoderm and epiblast of gastrulating chick embryos have some HNK-1-related proteins in common, while others are unique to specific tissues. Attempts have been made to identify these proteins using Western blots and antibodies known to recognize HNK-1-related molecules, but none of the antibodies used identify the bands unique to any of the tissues studied. We conclude that these proteins may be novel members of the HNK-1/L2 family, and that they may have a role in cell interactions during early development.

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 209-216
Author(s):  
Nikolas Zagris

Morphologically distinct erythroid cell types characteristic of the primitive and the definitiveerythroid cell lines, and embryonic and adult haemoglobins are produced when the unin-cubated chick blastoderm is cultured ventral side down on a filter raft to inhibit morphogeneticmovements and subsequent primitive-streak formation mechanically in serum-free minimalessential medium. The primitive and definitive erythroid cell populations appear consecutivelyin culture even though there is no axis formation nor apparent morphogenesis. The informa-tion to produce both the early and late haemoglobins and erythroid cell types is independentof axis formation and of specific extra-embryonic influences, such as progressive inductionexerted by the yolk mass.


2021 ◽  
Vol 22 (15) ◽  
pp. 8224
Author(s):  
Linda Krisch ◽  
Gabriele Brachtl ◽  
Sarah Hochmann ◽  
André Cronemberger Andrade ◽  
Michaela Oeller ◽  
...  

Several protocols exist for generating megakaryocytes (MKs) and platelets from human induced pluripotent stem cells (hiPSCs) with limited efficiency. We observed previously that mesoderm induction improved endothelial and stromal differentiation. We, therefore, hypothesized that a protocol modification prior to hemogenic endothelial cell (HEC) differentiation will improve MK progenitor (MKP) production and increase platelet output. We further asked if basic media composition affects MK maturation. In an iterative process, we first compared two HEC induction protocols. We found significantly more HECs using the modified protocol including activin A and CHIR99021, resulting in significantly increased MKs. MKs released comparable platelet amounts irrespective of media conditions. In a final validation phase, we obtained five-fold more platelets per hiPSC with the modified protocol (235 ± 84) compared to standard conditions (51 ± 15; p < 0.0001). The regenerative potency of hiPSC-derived platelets was compared to adult donor-derived platelets by profiling angiogenesis-related protein expression. Nineteen of 24 angiogenesis-related proteins were expressed equally, lower or higher in hiPSC-derived compared to adult platelets. The hiPSC-platelet’s coagulation hyporeactivity compared to adult platelets was confirmed by thromboelastometry. Further stepwise improvement of hiPSC-platelet production will, thus, permit better identification of platelet-mediated regenerative mechanisms and facilitate manufacture of sufficient amounts of functional platelets for clinical application.


Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5127-5138 ◽  
Author(s):  
S.B. Shah ◽  
I. Skromne ◽  
C.R. Hume ◽  
D.S. Kessler ◽  
K.J. Lee ◽  
...  

In the chick embryo, the primitive streak is the first axial structure to develop. The initiation of primitive streak formation in the posterior area pellucida is influenced by the adjacent posterior marginal zone (PMZ). We show here that chick Vg1 (cVg1), a member of the TGFbeta family of signalling molecules whose homolog in Xenopus is implicated in mesoderm induction, is expressed in the PMZ of prestreak embryos. Ectopic expression of cVg1 protein in the marginal zone chick blastoderms directs the formation of a secondary primitive streak, which subsequently develops into an ectopic embryo. We have used cell marking techniques to show that cells that contribute to the ectopic primitive streak change fate, acquiring two distinct properties of primitive streak cells, defined by gene expression and cell movements. Furthermore, naive epiblast explants exposed to cVg1 protein in vitro acquire axial mesodermal properties. Together, these results show that cVg1 can mediate ectopic axis formation in the chick by inducing new cell fates and they permit the analysis of distinct events that occur during primitive streak formation.


Development ◽  
1974 ◽  
Vol 32 (2) ◽  
pp. 445-459
Author(s):  
B. Levak-Švajger ◽  
A. Švajger

Single germ layers (or combinations of two of them) were isolated from the primitive streak and the head-fold stage rat embryos and grown for 15 days under the kidney capsule of syngeneic adult animals. The resulting teratomas were examined histologically for the presence of mature tissues, with special emphasis on derivatives of the primitive gut. Ectoderm isolated together with the initial mesodermal wings at the primitive streak stage gave rise to tissue derivatives of all three definitive germ layers. Derivatives of the primitive gut were regularly present in these grafts. At the head-fold stage, isolated ectoderm (including the region of the primitive streak) differentiated into ectodermal and mesodermal derivatives only. Endoderm isolated at the primitive streak stage did not develop when grafted and was always completely resorbed. At the head-fold stage, however, definitive endoderm differentiated into derivatives of the primitive gut if grafted together with adjacent mesoderm. These findings indirectly suggest the migration of prospective endodermal cells from the primitive ectoderm, and therefore a general analogy with the course of events during gastrulation in the chick blastoderm.


2018 ◽  
Vol 51 (3) ◽  
pp. 1354-1363 ◽  
Author(s):  
Yang Li ◽  
Liquan Tong ◽  
Jingyan Zhang ◽  
Yafeng Zhang ◽  
Feng  Zhang

Background/Aims: Liver ischemia-reperfusion (I/R) injury is a pathological process that often occurs during liver and trauma surgery. There are numerous causes of liver I/R injury, but the mechanism is unknown. Galangin (GA) is a flavonoid, a polyphenolic compound widely distributed in medicinal herbs that has anti-inflammatory, antioxidant, and antitumor activity. This study evaluated the protective effect of GA on hepatic I/R injury. Methods: An I/R model was created in male Wistar rats by clamping the hepatoportal vein, hepatic artery and hepatic duct for 30 min followed by reperfusion for 2 h. A hypoxia/restoration (H/R) model was established in buffalo rat liver (BRL) cells by hypoxia for 4 h followed by normoxic conditions for 10 h. The extent of liver injury was assayed by serum ALT/AST, hepatic histology, and MPO activity. Oxidative stress was assayed by serum superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA). Expression of apoptosis-related proteins in BRL cells was assayed in western blots. Expression of AKT and p-AKT proteins in vivo and vitro were assayed in western blots. Results: GA significantly decreased ALT/AST expression, reversed changes in oxidative stress markers induced by I/R, and mediated caspase-3 activity expression of apoptosis-related proteins in vivo and in vitro. Methylthiazol tetrazolium (MTT) assay, flow cytometry, and Hoechst 33258 staining confirmed that GA inhibited apoptosis of BRL cells. GA also increased the expression of phosphorylated AKT after H/R. Conclusion: GA reduced liver I/R injury both in vivo and vitro and inhibited BRL cell apoptosis. PI3K/AKT signaling have been involved. GA may protect against liver I/R and be a potential therapeutic candidate.


1937 ◽  
Vol 14 (3) ◽  
pp. 319-334 ◽  
Author(s):  
M. ABERCROMBIE ◽  
C. H. WADDINGTON

1. Grafts consisting of pieces of primitive streak from blastoderms in the primitive streak stage were placed under the primitive streak of blastoderms also in this stage. 2. Various effects of the host on the graft are described, particularly the reversal of the antero-posterior orientation of the graft, the alteration of the regional character of the graft so as to conform with the host tissues at the same level, the suppression of differentiation in the posterior end of the primitive streak, and the incorporation of the graft tissues into the host. 3. A considerable number of inductions occurred, since the host axis often apparently shifts to one side of the graft. The inductions are of two kinds, the normal evocation by graft mesoderm, resulting usually in the formation of superfluous neural tissue; and the complementary induction of a normal secondary axis, which it is supposed is most often due to the preliminary induction of a primitive streak in the host. 4. Various effects of the graft on the host occur. In particular the disturbance of the head mesenchyme suggests that foregut diverticula are produced where head mesenchyme joins lateral plate mesothelium.


2020 ◽  
Author(s):  
Simone Probst ◽  
Sagar ◽  
Jelena Tosic ◽  
Carsten Schwan ◽  
Dominic Grün ◽  
...  

AbstractAnterior mesoderm (AM) and definitive endoderm (DE) progenitors represent the earliest embryonic cell types that are specified during germ layer formation at the primitive streak (PS) of the mouse embryo. Genetic experiments indicate that both lineages segregate from Eomes expressing progenitors in response to different NODAL signaling levels. However, the precise spatiotemporal pattern of the emergence of these cell types and molecular details of lineage segregation remain unexplored. We combined genetic fate labeling and imaging approaches with scRNA-seq to follow the transcriptional identities and define lineage trajectories of Eomes dependent cell types. All cells moving through the PS during the first day of gastrulation express Eomes. AM and DE specification occurs before cells leave the PS from discrete progenitor populations that are generated in distinct spatiotemporal patterns. Importantly, we don’t find evidence for the existence of progenitors that co-express markers of both cell lineages suggesting an immediate and complete separation of AM and DE lineages.Summary statementCells lineages are specified in the mouse embryo already within the primitive streak where Mesp1+ mesoderm and Foxa2+ endoderm are generated in a spatial and temporal sequence from unbiased progenitors.


1989 ◽  
Vol 9 (1) ◽  
pp. 232-240 ◽  
Author(s):  
C M Isacke ◽  
R A Lindberg ◽  
T Hunter

p36 and p35 are distinct but related proteins that share many structural and biochemical features which were first identified as major substrates for protein-tyrosine kinases. Subsequently, both proteins have been shown to be Ca2+-, phospholipid-, and F-actin-binding proteins that underlie the plasma membrane and are associated with the cortical cytoskeleton. Recent reports have claimed that these proteins function as lipocortins, i.e., phospholipase A2 inhibitors that mediate the anti-inflammatory action of glucocorticoids. To investigate this possibility and to learn more about the functions of p36 and p35, we used human-specific anti-p36 and anti-p35 monoclonal antibodies to determine whether the expression or secretion of either protein was inducible by dexamethasone in the human U-937 myeloid cell line and in other human cell types. Additionally, we examined the levels of mRNA for both proteins. No effect of dexamethasone was observed on p36 or p35 expression at either the mRNA or protein level, nor were these proteins secreted under any of the culture conditions investigated. However, it was observed that in these cells the rate of synthesis and accumulation of both proteins was increased when the U-937 cells were induced to differentiate in culture to adherent macrophagelike cells. This offers a model system with which to study the control of p36 and p35 expression.


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