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At least 37 records · Page 2Linked to original sources
PubMed1993

Sequential expression of HNF-3 beta and HNF-3 alpha by embryonic organizing centers: the dorsal lip/node, notochord and floor plate.

Axial patterning in the nervous system of vertebrate embryos depends on inductive signals that derive from the organizer region (the dorsal lip in amphibians and the node in birds and mammals) and leter from the notochord and floor plate. Previous studies have shown that Pintallavis, a member of the HNF-3/fork head transcription factor family, is expressed selectively by these cell groups in frog embryos and may be involved in regulating neural development. We report here that in early rat and mouse embryos, the embryonic endoderm, the node, the notochord and the floor plate express two related transcription factors, HNF-3 alpha and HNF-3 beta, which also function in the control of liver cell differentiation. Early embryonic tissues express variant forms of HNF-3 beta which derive from the use of 5' alternative exons. Within the organizer region and notochord, HNF-3 beta and HNF-3 alpha have distinct temporal patterns of expression and appear in partially overlapping domains. The early expression pattern of mammalian HNF-3 beta in the node, notochord and midline neural plate cells is similar to that of Pintallavis in frog embryos. There does not appear to be a Pintallavis homologue in mice. This prompted us to isolate and analyze the expression of the frog HNF-3 beta gene. In frog embryos, HNF-3 beta is expressed in the dorsal lip, pharyngeal endoderm and floor plate. In contrast to mammalian HNF-3 beta, the onset of frog HNF-3 beta expression in neural tissue occurs after neural tube closure. Thus, the combined expression patterns of Pintallavis and HNF-3 beta in frogs is equivalent to that of HNF-3 beta in rats and mice. Within neural tissue, the onset of expression of these regulatory genes define successive stages in the differentiation of floor plate cells. The results reported here show that closely related members of the HNF-3/fork head gene family are expressed by axial midline cell groups involved in neural induction and patterning and suggest the involvement of these genes in the development of the vertebrate neuraxis.

Amino Acid Sequence↗
PubMed2002

ErbB signaling regulates lineage determination of developing pancreatic islet cells in embryonic organ culture.

The neuregulin (NRG)/epidermal growth factor (EGF) family of growth factors consists of several ligands that specifically activate four erbB receptor-tyrosine kinases, namely erbB-1 (EGF-R), erbB-2 (neu), erbB-3, and erbB-4. We have previously shown that islet morphogenesis is impaired and beta-cell differentiation delayed in mice lacking functional EGF-R [EGF-R (-/-)]. The present study aims to clarify which erbB ligands are important for islet development. Pancreatic expression of EGF, TGF-alpha, heparin-binding EGF, betacellulin (BTC), and NRG-4 was detected as early as embryonic d 13 (E13). Effects of these ligands were studied in E12.5 pancreatic explant cultures grown for 5 d ex vivo. None of the growth factors affected the ratio of endocrine to exocrine cells. However, significant effects within the endocrine cell populations were induced by EGF, BTC, and NRG-4. beta-Cell development was augmented by BTC, whereas the development of somatostatin-expressing delta-cells was stimulated by NRG-4. Both ligands decreased the numbers of glucagon-containing alpha-cells. The effect of BTC was abolished in the EGF-R (-/-) mice. A soluble erbB-4 binding fusion protein totally inhibited the effects of NRG-4 but not of BTC. Neutralization of endogenous NRG-4 activity in the model system effectively inhibited delta-cell development, indicating that this erbB4-ligand is an essential factor for delineation of the somatostatin-producing delta-cells. Our results suggest that ligands of the EGF-R/erbB-1 and erbB-4 receptors regulate the lineage determination of islet cells during pancreatic development. BTC, acting through EGF-R/erbB-1, is important for the differentiation of beta-cells. This could be applied in the targeted differentiation of stem cells into insulin-producing cells.

Animals↗
PubMed2004

Transplantation of embryonic organs - kidney and pancreas.

One novel solution to the shortage of human organs available for transplantation envisions 'growing' new organs in situ via xenotransplantation of developing anlagen from animal embryos. We and others have shown that renal anlagen (metanephroi) transplanted into animal hosts undergo differentiation and growth, become vascularized by blood vessels of host origin and exhibit excretory function. Metanephroi can be stored for up to 3 days in vitro prior to transplantation with no impairment in growth or function post-implantation. Metanephroi can be transplanted across both concordant (rat to mouse) and highly disparate (pig to rodent) xenogeneic barriers. Similarly, pancreatic anlagen undergo growth, differentiation and secrete insulin in a physiological manner following intraperitoneal placement. Implantation of the embryonic pancreas, is followed by selective differentiation of islet as compared to acinar components. Here we review studies exploring the potential therapeutic use of embryonic kidney or pancreas transplantation.

Animals↗
PubMed1995

Cytoplasmic HSP70 homologues of pea: differential expression in vegetative and embryonic organs.

Eukaryotes express several cytoplasmic HSP70 genes, and their encoded proteins participate in diverse cellular processes. Three cDNAs encoding highly expressed cytoplasmic HSP70 homologues from Pisum sativum were cloned and characterized. They were designated PsHSP71.2, PsHSC71.0, and PsHSP70b. These HSP70 genes have different expression profiles in leaves: PsHSP71.2 is observed only in response to heat stress, PsHSC71.0 is present constitutively, and PsHSP70b is weakly constitutively expressed, but induced strongly in response to heat stress. In addition to being heat induced, the PsHSP71.2 mRNA is also expressed in zygotic, but not maternal organs of developing pea seeds, while PsHSC71.0 and PsHSP70b mRNAs are present in maternal and zygotic organs throughout seed development. Immunoblot analysis of parallel protein samples detects a 70 kDa polypeptide in all samples, and a 72 kDa polypeptide that corresponds to the PsHSP71.2 gene product is observed in cotyledons beginning at mid-maturation and in axes beginning between late maturation and desiccation. This polypeptide is not detected in the seed coat. The 72 kDa polypeptide remains abundant in both cotyledons and axes through germination, but declines substantially between 48 and 72 h after the onset of inbibition. Differential control of HSP70 expression during heat stress, seed maturation, and germination is consistent with the hypothesis that there are functional distinctions between cytoplasmic HSP70s.

Amino Acid Sequence↗
PubMed1990

The expression of the TGF beta 1 gene in the first trimester human eye and other embryonic organs.

We have examined the expression of the transforming growth factor beta 1 gene in a variety of tissues in the developing human embryo. Northern blot analysis revealed the presence of TGF B1 mRNA in the 10-12 week old eye as well as in most first trimester organs with the notable exception of the yolk sack. In an attempt to determine the topographical distribution of TGF B1 transcripts within the eye, we found that messenger RNA levels were higher in the posterior regions of the eye globe.

Embryo, Mammalian↗
PubMed1997

Analyses of extrathymic T cell differentiation in nu/nu mice by grafting embryonal organs.

Fetal (days 15 to 17) organs such as the small intestine, stomach and pancreas were engrafted under the renal capsules of athymic nude (nu/nu) mice to examine the capacity of these organs to induce the differentiation of T cells. Eight weeks after engraftment, the engrafted organs had differentiated into adult-type organs histologically. In the lamina propria of the engrafted small intestine, large intestine, and stomach, there were clusters of lymphocytes or lymphoid follicles, which included Thy1.2+ or CD4+ T cells. Flow cytometric analyses revealed that the lymphocytes from the lymph nodes of sham-, esophagus-, or pancreas-engrafted mice included very few T cells (1.20%), whereas those from the lymph nodes of the fetal small intestine-, large intestine-, or stomach-engrafted mice included significant numbers of T cells (8.36%) 8 weeks after engraftment, although there were not as many as in the fetal thymus-engrafted mice (17.97%). The peripheral T cells in the small intestine-, large intestine-, or stomach-engrafted mice were of bone marrow origin, and consisted of Thy1.2+, CD3+, and CD4+8-, or CD4-8+ with T cell receptor (TcR) alpha beta cells. Taken together, these findings indicate that not only the murine small intestine and large intestine but also the stomach have the capacity to induce the differentiation of T cells.

Animals↗
PubMed1971

Further studies on the growth of rubella virus in human embryonic organ cultures: preliminary observations on interferon production in these cultures.

Organ cultures prepared from 15 different organs obtained from 43 fetuses were consistently found to support the growth of rubella virus, irrespective of the gestational age of the fetus or the strain of rubella virus inoculated. Although rubella virus replicated in fetal lenses, adult lenses did not support the growth of rubella virus. Organs obtained from four fetuses between 8 and 17 weeks gestational age produced similar titres of an inhibitor which had the characteristics of interferon. The use of Trowell T8 medium and incubation in a mixture of 5% CO(2) in oxygen provided the most suitable conditions for the maintenance of most organ cultures. Under these circumstances it was possible to obtain adequate histological preparations from these organs, but light microscopy studies revealed no significant differences in sections of rubella inoculated and control organ cultures.

Brain↗
PubMed1996

The alteration of ultrastructure and immunoreactivity of human embryonic organ of Corti tissue culture after exposure to aminoglycoside (neomycin) ototoxicity.

Using electron microscopy and GABA immunohistochemistry we evaluated the effects on human embyronic organ of Corti tissue culture of exposure to the ototoxic aminoglycoside antibiotic neomycin at a dose of 1 mM for 48 to 96 hrs. Neomycin induces the formation of multilamellar myeloid structures. These lesions, found only in the basal coil but both in inner and outer hair cells, were characteristic of the membrane-associated neomycin-induced damage. A large amount of lipofucsin and numerous lipoid vacuoles as well as vesicle-filled mound-like protrusions were also observed after exposure to neomycin. It seems there is no obvious effect on GABAergic innervation.

Aminoglycosides↗
PubMedDate not supplied

[Cultivation of reovirus in human embryonic organ cultures].

Human embryo lung and intestine organ cultures were infected with reovirus type 3 isolated from the lungs of a newborn baby. In the lung organ culture the virus multiplied quite intensively producing in the bronchi characteristic 4-6 nuclei cells.

Cytopathogenic Effect, Viral↗