Amino Acids in Developing Tissues of Xenopus laevis

Development ◽  
1956 ◽  
Vol 4 (4) ◽  
pp. 327-346
Author(s):  
E. M. Deuchar
Keyword(s):  
Amino Acids ◽  
Xenopus Laevis ◽  
Chemical Nature ◽  
Radioactive Tracer ◽  
Protein Molecule ◽  
Chick Embryos ◽  
Histological Differentiation ◽  
Tissue Specific ◽  
Tracer Techniques ◽  
Specific Antigens

Information about embryonic amino acids is of interest because of the possible light it throws on the differentiation of embryonic proteins. It is known from immunological work on amphibian and chick embryos (Cooper, 1946; Clayton, 1953; Ebert, 1950, 1952) that tissue-specific antigens are detectable before histological differentiation has taken place (Ten Cate & van Doorenmaalen, 1950). Although the chemical nature of antigenic differences is not yet properly known, recent evidence suggests that they may include differences in the number and arrangement of amino acids in N-terminal residues of the protein molecule (Porter & Sanger, 1948; McFadden & Smith, 1953; Putnam, 1953). For this reason, and on general grounds too, one may expect the formation of antigens in the embryo to be accompanied by altered arrangements of the proteinbound amino acids. Radioactive tracer techniques have made it possible to detect the uptake of amino acids into embryonic proteins (Waddington & Sirlin, 1954; Feldman & Waddington, 1955), but so far this information has not been related to the appearance of individual antigens.

UTILIZATION OF CARBOHYDRATES AND AMINO ACIDS BY MICROCOCCUS RADIODURANS

1960 ◽  
Vol 6 (3) ◽  
pp. 289-298 ◽  
Author(s):  
Harkison D. Raj ◽  
Frances L. Duryee ◽  
Anne M. Deeney ◽  
Chih H. Wang ◽  
Arthur W. Anderson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Tricarboxylic Acid Cycle ◽  
Radioactive Tracer ◽  
Defined Medium ◽  
Tricarboxylic Acid ◽  
Chemically Defined Medium ◽  
Acid Cycle ◽  
Tracer Techniques ◽  
Simple Carbohydrates

The nutrition and metabolism of a recently isolated Micrococcus species resistant to closes of gamma radiation as high as 6 × 106 r.e.p. were studied by manometric and radioactive tracer techniques. Methionine, the only amino acid shown to be essential in a chemically defined medium, appears to be rapidly incorporated into the cells. DL-Glutamic acid is readily metabolized, the D isomer apparently after an initial lag. Among the simple carbohydrates, fructose, glucose, and glycerol are readily utilized. The operation of the tricarboxylic acid cycle is suggested by the oxidation of certain TCA intermediates. The prompt conversion of C-1 of gluconate to CO2, in the presence of glucose, may indicate that a C1–C5 cleavage pathway is operative for catabolism of glucose in this organism.

scholarly journals Tissue-specific expression of the Ets gene Xsap-1 during Xenopus laevis development

2001 ◽  
Vol 109 (2) ◽  
pp. 433-436 ◽  
Author(s):  
Oliver Nentwich ◽  
Frank E. Münchberg ◽  
Götz Frommer ◽  
Alfred Nordheim
Keyword(s):  
Xenopus Laevis ◽  
Specific Expression ◽  
Tissue Specific ◽  
Tissue Specific Expression

Differentiation of allantoic endoderm implanted into the presumptive digestive area in avian embryos. A study with organ-specific antigens

Development ◽  
1984 ◽  
Vol 80 (1) ◽  
pp. 137-153
Author(s):  
Sadao Yasugi
Keyword(s):  
Digestive Tract ◽  
Intestinal Epithelium ◽  
Digestive Organ ◽  
Chick Embryos ◽  
Avian Embryos ◽  
Digestive Organs ◽  
Organ Specific ◽  
Specific Antigens

Quail allantoic endoderm was implanted into the presumptive digestive-tract area of chick embryos, and the differentiation of the endoderm was examined morphologically and immunocytochemically with antisera against pepsinogens and sucrase. The allantoic endoderm was incorporated into the host digestive organs. It often became continuous with the host endoderm and formed a chimaeric digestive-tract epithelium. It differentiated morphologically into the epithelium of the digestive organ into which it was incorporated, showing the morphological inductive ability in situ of the digestive-tract mesenchyme against the allantoic endoderm. However, the allantoic endoderm did not produce pepsinogens even when it was incorporated into the host proventricular mesenchyme and formed well-developed proventricular glands. This result indicates that the heterotypic morphogenesis of the allantoic endoderm is not necessarily accompanied by the heterotypic cytodifferentiation. In contrast, the anti-sucrase antiserum-reactive cells often differentiated in the allantoic endoderm incorporated into not only the intestine but also other organs. This confirmed our previous observation that the allantoic endoderm has a tendency to differentiate into the intestinal epithelium in the heterologous environment.

trans activation of rat phosphoenolpyruvate carboxykinase (GTP) gene expression by micro-coinjection of rat liver mRNA in Xenopus laevis oocytes

1989 ◽  
Vol 9 (11) ◽  
pp. 5244-5247
Author(s):  
N Benvenisty ◽  
T Shoshani ◽  
Y Farkash ◽  
H Soreq ◽  
L Reshef
Keyword(s):  
Gene Expression ◽  
Xenopus Laevis ◽  
Reporter Gene ◽  
Rat Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Xenopus Laevis Oocytes ◽  
Activation Process ◽  
Tissue Specific ◽  
Chimeric Construct

To study the liver-specific trans activation of the rat phosphoenolpyruvate carboxykinase (PEPCK) gene, the PEPCK promoter was linked to a reporter gene and was microinjected into Xenopus laevis oocytes alone or in conjunction with rat liver poly(A)+ RNA. The rat liver mRNA markedly enhanced the expression of the PEPCK-chimeric construct. This effect appeared to be sequence specific, as it was dependent on the presence of the intact promoter. Moreover, the RNA effect was limited to mRNA preparations from PEPCK-expressing tissues only. Finally, microinjection of size-fractionated liver mRNA revealed that the trans-acting factor(s) is encoded by RNA of 1,600 to 2,000 nucleotides, providing a direct bioassay for the gene(s) involved in this tissue-specific trans-activation process.

scholarly journals THE CHEMICAL NATURE OF MACROPHAGE RNA-ANTIGEN COMPLEXES AND THEIR RELEVANCE TO IMMUNE INDUCTION

1969 ◽  
Vol 130 (3) ◽  
pp. 557-574 ◽  
Author(s):  
Georges E. Roelants ◽  
Joel W. Goodman
Keyword(s):  
Amino Acids ◽  
Complex Formation ◽  
Chemical Nature ◽  
Divalent Cations ◽  
Chelating Agent ◽  
Total Absence ◽  
Synthetic Polypeptides ◽  
Antigen Complex ◽  
Anionic Groups ◽  
Do So

10 different compounds, including natural and synthetic polypeptides, proteins, polysaccharides, amino acids, and steroid hormones, were assayed for their capacity to form complexes with peritoneal exudate cell RNA. Only molecules carrying negatively charged groups were able to do so. The formation of RNA-antigen complexes was unrelated to the immuno-potency of the "antigen," was not an enzyme-dependent reaction, did not require the synthesis of RNA following introduction of the antigen, did not seem to involve antigen-specific RNAs, was not specific for macrophages, since HeLa cells could be used as effectively, and occurred when purified RNA was mixed with antigen only in the presence of divalent cations. The complexes were very stable, once formed, but could be dissociated by exhaustive dialysis against buffers containing a chelating agent. The macrophage RNA-antigen complex therefore appears to be a chelate between anionic groups on the two components. Based on the total absence of a relationship between immunogenicity and the capacity to form such complexes, as well as the nonspecific nature of complex formation at every level examined, it appears unlikely that RNA-antigen complexes play a physiologically significant role in immune induction.

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