Search results for "Biochemistry"

Phospholipase activities associated with the tonoplast from Acer pseudoplatanus cells: identification of a phospholipase A1 activity

1995

In higher plants, the lipolytic enzymes and their physiological functions are not well characterized [1]. Most reports demonstrated that phospholipid catabolism in plants is achieved by the concerted actions of membrane-bound enzymes including phospholipase D, phosphatidate phosphatase, lipolytic acyl hydrolases and lipoxygenases [1,2]. With the exception of the phospholipase D, the literature on plant phospholipases is still very limited. We previously reported that tonoplast from Acer pseudoplatanus cells contains small amounts of phosphatidc acid and lysophospholipids, which were produced together with free fatty acids, particularly after addition of Ca2+[3]. These data suggested the pos…

Der Zellkern - eine Stadt in der Zelle

2016

Gespeicherte genetische Information allein nutzt nichts, wenn sie nicht zur richtigen Zeit und am richtigen Ort abgerufen werden kann. Die Verpackung der DNA im Chromatin des Zellkerns und dessen dynamische, raum-zeitliche Anordnung haben einen entscheidenden Einfluss auf die Genexpression und weitere Funktionen des Zellkerns. In dieser Ubersichtsarbeit beschreiben die Verfasser die Entwicklung der experimentellen Zellkernarchitektur-Forschung und die damit einhergehenden Veranderungen der Vorstellungen zur funktionellen Organisation des Zellkerns.

IAP et cancer : le NO contre-attaque

2021

Dans le cadre du Master 2 de l’université EPHE-PSL (Master Sciences du vivant, cursus IMaGHE, parcours Physiopathologie intégrative [PPI]), des étudiants se sont confrontés à la rédaction d’une nouvelle scientifique. Ces étudiants ayant choisi une spécialisation en cancérologie, l’équipe pédagogique leur a proposé de faire une synthèse d’articles sur deux thématiques : 1) les protéines IAP et un mécanisme original de régulation de leur activité par S-nitrosylation et 2) la séparase, dont un article paru récemment dans Nature montre qu’elle jouerait un rôle inattendu dans la protection des cellules contre la transformation tumorale. Organisés en binôme ou trinôme, les étudiants ont rédigé de…

γ-Glutamyl cysteine suppresses TNF-α up-regulation via protein phosphatases in acute pancreatitis

2016

Biocide

2017

Biodeterioration represents a revealing problem for the conservation of cultural heritage. It can be identified as a complex interaction within the ecosystem of a microbial community and its substrate and involves physical and chemical alterations resulting from biological and metabolic activity. Designing a diagnostic approach for evaluating the extent of the damage, identifying the biological community, and opting for an efficient methodology aimed at eliminating deteriogens is equally complicated. The correct approach would require understanding the nature of the biodeterioration and implementing methodologies respectful of human health which, however, avoid the indiscriminate killing of…

Cancers du côlon : prise en charge moléculaire

2018

Resume Le demembrement moleculaire des cancers et en particulier des cancers colorectaux conduit a des prises en charge de plus en plus adaptees et de plus en plus complexes. Ce demembrement a abouti a de nombreuses classifications et finalement a une classification moleculaire consensuelle en 2015. Cette classification consensuelle reste pour l’instant non utilisable au quotidien. Plusieurs facteurs moleculaires (statut MSS/MSI, statut BRAF, statut RAS) sont desormais indispensables a la prise en charge du cancer colorectal que ce soit en situation adjuvante ou metastatique. D’autres facteurs tels que le statut HER2 et l’expression de mir-31-3p sont regulierement pris en compte au cas par …

Zilienabhängige RPE-Zellentwicklung und der WNT-Signalweg

2020

ZusammenfassungDas retinale Pigmentepithel (RPE) ist eine hochpolarisierte Einzelschicht quaderförmiger Epithelzellen, die dicht mit Melanin gepackt sind. Sie liegt zwischen den lichtempfindlichen Außensegmenten der Photorezeptoren und der Aderhaut (Choroidea), spielt eine essenzielle Rolle bei der Entwicklung der Photorezeptoren und übernimmt wichtige Funktionen in Bezug auf Nährstoffversorgung und Erhaltung, im Retinalstoffwechsel und bei der Abschirmung von der Blutversorgung der Aderhaut. Die Photorezeptoren durchlaufen täglich einen Erneuerungsprozess, bei dem 10% der äußeren Segmente durch das retinale Pigmentepithel phagozytiert werden. Dies erfordert eine enge Wechselwirkung zwische…

2019

Integral membrane proteins of the aquaporin family facilitate rapid water flux across cellular membranes in all domains of life. Although the water-conducting pore is clearly defined in an aquaporin monomer, all aquaporins assemble into stable tetramers. In order to investigate the role of protomer–protomer interactions, we analyzed the activity of heterotetramers containing increasing fractions of mutated monomers, which have an impaired oligomerization propensity and activity. In order to enforce interaction between the protomers, we designed and analyzed a genetically fused homotetramer of GlpF, the aquaglyceroporin of the bacterium Escherichia coli (E. coli). However, increasing fractio…

Spectrophotometric study of DNA interactions with ftorafur and its elementoorganic derivatives

2017

ABSTRACTFtorafur is an antimetabolite antitumour drug successfully used for treatment of various tumours. It is generally accepted that ftorafur is converted to 5-fluoruracil. However, some data indicate direct interactions of the compound with DNA. To test this hypothesis we have performed spectrophotometric study of DNA interactions of ftorafur and some of its elementoorganic derivatives with DNA. UV-VIS spectra of the tested compounds were recorded in absence and presence of increasing amounts of DNA. DNA caused a hypochromic effect in spectra of ftorafur, similar, but weaker effect was observed in 5-fluoruracil spectra. Trimethylgermyl derivative of ftorafur manifested a higher DNA-bind…

Assembly of Transmembrane b-Type Cytochromes and Cytochrome Complexes

2016

Cytochromes are involved in charge-transfer reactions, and many cytochromes contain a transmembrane domain and are part of membrane-localized electron transfer chains. Protoporphyrin IX (heme b) is the first heme product in the tetrapyrrole/heme biosynthesis pathway. In contrast to c-type cytochromes, there is no need for a specialized machinery catalyzing covalent attachment of the heme molecule to a b-type apo-cytochrome, nor is the cofactor further modified, as in a-, d- and o-type cytochromes. Thus, formation of a holo-cytochrome is relatively simple for b-type cytochromes, and this class of proteins probably represents the most ancient members of transmembrane cytochromes. However, ass…