Über das Vorkommen eines spezifischen Enzyms der Glucuronsäurebildung im menschlichen Amnion

Zusammenfassung Die Amnien von reifen menschlichen Plazenten wurden auf das Vorkommen der Uridindiphosphatglucose-Dehydrogenase (UDPG-DH), eines Enzyms der Glucuronsäurebildung, untersucht. Dabei konnte sowohl in den Zellen des Amnionepithels als auch in den Fibroblasten des Amnionmesenchyms eine hohe Aktivität festgestellt werden. Die Bedeutung dieses Befundes im Amnion wird im Zusammenhang mit der Stellung der Glucuronsäure im intermediären Stoffwechsel besprochen.

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About the existence of a specific enzyme for the synthesis of glucuronic acid in the human amnion

Summary In order to trace uridine diphosphate glucose dehydrogenase, an enzyme for the synthesis of glucuronic acid, the amnions of mature human placentas were investigated. High activity could be found in the amniotic epithelium as well as in the fibroblasts of the amniotic mesenchyma. These findings are discussed in connection with the task of glucuronic acid in general biological pathways.

Wir danken Herrn Dr. med. vet. J. Schlüns (Institut für Veterinär-Anatomie der Freien Universität Berlin) für wertvolle Ratschläge, unserer technischen Assistentin Frau E. Hartleben für die Unterstützung bei der Bearbeitung des Materials.     

Changes in enzymic activities of UDP-D-glucuronate decarboxylase and UDP-D-xylose 4-epimerase during cell division and xylem differentiation in

The time course of the specific activities of UDP-D-glucuronate decarboxylase (E.C. 4.1.1.35) and UDP-D-xylose 4-epimerase (E.C. 5.1.3.5) have     

Knock-in of the duck retinoic acid-inducible gene I (RIG-I) into the Mx gene in DF-1 cells enables both stable and immune response-dependent RIG-I expression

Waterfowls, such as ducks, are natural hosts of avian influenza virus (AIV) and can genetically limit the pathogenicity. On the other hand, some AIV strains cause severe pathogenicity in chickens. It is suggested that differences in the pathogenicity of AIV infection between waterfowls and chickens are related to the expression of retinoic acid-inducible gene I (RIG-I), a pattern recognition receptor that chickens evolutionally lack. Here, we knocked-in the duck RIG-I bearing the T2A peptide sequence at the 3′ region of the Mx, an interferon-stimulated gene (ISG), in chicken embryo fibroblast cells (DF-1) using the precise integration into target chromosome (PITCh) system to control the duck RIG-I expression in chickens. The expression patterns of the duck RIG-I were then analyzed using qPCR. The knocked-in DF-1 cells expressed RIG-I via the stimulation of IFN-β and poly(I:C) in a dose-dependent manner. Moreover, poly(I:C) stimulation in the knocked-in DF-1 cells upregulated RIG-I-like receptor (RLR) family signaling pathway-related genes IFN-β, OASL, and IRF7. The IFN-β-dependent expression of RIG-I and upregulation of IFN-β in the poly(I:C) stimulation demonstrated a positive-feedback loop via RIG-I, usually evident in ducks. Overall, this novel strategy established RIG-I-dependent immune response in chickens without overexpression of RIG-I and disruption of the host genes.     

The metabolic integrity of Fasciola hepatica during in vitro maintenance

Levels of metabolic intermediates and end products in F. hepatica after 24 and 48 h in Hédon-Fleig salt solution with added glucose were compared with levels obtained immediately on removal from the host. Glycogen levels dropped initially, probably due to the expulsion of eggs; thereafter they remained constant. Internal glucose concentrations increased as the parasites equilibrated with the medium. Other changes in internal pool sizes were consistent with regulation to the in vitro conditions. ATP levels increased; ATP/ADP ratios were maintained. Comparisons of mass action ratios and equilibrium constants suggest that hexokinase, pyruvate kinase and phosphofructokinase are regulatory. Output of excretory products approached linearity; from the calculated regressions the proportions of lactate, acetate and propionate were 1: 2: 4. The implications for metabolic regulation in F. hepatica are briefly discussed, and it is concluded that, for at least 48 h in vitro, energy metabolism is not adversely affected.     

Evidence for a geranyl-diphosphate synthase located within the plastids of Vitis vinifera L. cultivated in vitro

Intact plastids from cell suspensions of Vitis vinifera L. cv. Muscat de Frontignan, free of detectable contamination by other particles as judged by the distribution of organelle-specific marker enzymes and by electron microscopy, exhibit geranyl-diphosphate synthase activity (EC 2.5.1.1). This synthase activity remains stable after tryptic digestion of unlysed organelles and is enhanced by plastid disruption. We conclude that the enzyme is located within the organelle. The possibility of an isopentenyl diphosphate/dimethylallyl diphosphate translocating system which would play a major role in the regulation of monoterpene metabolism is discussed.     

Functional Flexibility of the Transketolase Molecule

Transketolase is the simplest representative of the thiamine diphosphate-dependent enzymes. It was the first of these enzymes for which X-ray analysis was performed. Based on the data of X-ray studies and using the mutagenesis technique, the nature of functional groups of the enzyme involved in the interaction with substrates and cofactors and in the coenzyme activation was defined. Thus, considerable achievements have been made in studying the structure of transketolase. However, there is relatively little information on the conformational flexibility of the enzyme molecule while it is functioning, i.e., during its interaction with cofactors and substrates and in the course of intermediate product formation. This review summarizes mainly the results obtained in the author's group, as well as those rare data on this subject that could be found in literature.