Search results for "030102 biochemistry & molecular biology"
showing 10 items of 174 documents
The Greenland shark Somniosus microcephalus—Hemoglobins and ligand-binding properties
2017
A large amount of data is currently available on the adaptive mechanisms of polar bony fish hemoglobins, but structural information on those of cartilaginous species is scarce. This study presents the first characterisation of the hemoglobin system of one of the longest-living vertebrate species (392 +/- 120 years), the Arctic shark Somniosus microcephalus. Three major hemoglobins are found in its red blood cells and are made of two copies of the same a globin combined with two copies of three very similar beta subunits. The three hemoglobins show very similar oxygenation and carbonylation properties, which are unaffected by urea, a very important compound in marine elasmobranch physiology.…
Female sexual signaling in a capital breeder, the European glow-worm Lampyris noctiluca
2021
AbstractTheory predicts that because costs constrain female sexual signaling, females are expected to have a low signaling effort that is increased with passing time until mating is secured. This pattern of signaling is expected to result from females balancing the costs associated with a higher than optimal signaling effort and those costs associated with a low signaling effort that increase the likelihood of delayed mating. We tested whether this prediction applies in the common glow-worm Lampyris noctiluca (Coleoptera, Lampyridae), a capital breeding species in which females glow at night to attract males. Contrary to predictions, we found that the duration of female sexual signaling sig…
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.
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…
2018
ABC (ATP binding cassette) transporters, ubiquitous in all kingdoms of life, carry out essential substrate transport reactions across cell membranes. Their transmembrane domains bind and translocate substrates and are connected to a pair of nucleotide binding domains, which bind and hydrolyze ATP to energize import or export of substrates. Over four decades of investigations into ABC transporters have revealed numerous details from atomic-level structural insights to their functional and physiological roles. Despite all these advances, a comprehensive understanding of the mechanistic principles of ABC transporter function remains elusive. The human multidrug resistance transporter ABCB1, al…
Echovirus 1 internalization negatively regulates epidermal growth factor receptor downregulation
2016
We have demonstrated previously that the human picornavirus Echovirus 1 (EV1) triggers an infectious internalization pathway that follows closely, but seems to stay separate, from the epidermal growth factor receptor (EGFR) pathway triggered by epidermal growth factor (EGF). Here, we confirmed by using live and confocal microscopy that EGFR and EV1 vesicles are following intimately each other but are distinct entities with different degradation kinetics. We show here that despite being sorted to different pathways and located in distinct endosomes, EV1 inhibits EGFR downregulation. Simultaneous treatment with EV1 and EGF led to an accumulation of EGFR in cytoplasmic endosomes, which was evi…
Environmental aircraft noise aggravates oxidative DNA damage, granulocyte oxidative burst and nitrate resistance inOgg1–/–mice
2020
Background: Large epidemiological studies point towards a link between the incidence of arterial hypertension, ischaemic heart disease, metabolic disease and exposure to traffic noise, supporting t...