Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Biology  (13)
  • Chemistry
Type of Medium
Language
Year
  • 1
    Language: English
    In: PLoS ONE, 2011, Vol.6(5), p.e20112
    Description: The production and use of nanoparticles (NP) has steadily increased within the last decade; however, knowledge about risks of NP to human health and ecosystems is still scarce. Common knowledge concerning NP effects on freshwater organisms is largely limited to standard short-term (≤48 h) toxicity tests, which lack both NP fate characterization and an understanding of the mechanisms underlying toxicity. Employing slightly longer exposure times (72 to 96 h), we found that suspensions of nanosized (∼100 nm initial mean diameter) titanium dioxide (nTiO 2 ) led to toxicity in Daphnia magna at nominal concentrations of 3.8 (72-h EC 50 ) and 0.73 mg/L (96-h EC 50 ). However, nTiO 2 disappeared quickly from the ISO-medium water phase, resulting in toxicity levels as low as 0.24 mg/L (96-h EC 50 ) based on measured concentrations. Moreover, we showed that nTiO 2 (∼100 nm) is significantly more toxic than non-nanosized TiO 2 (∼200 nm) prepared from the same stock suspension. Most importantly, we hypothesized a mechanistic chain of events for nTiO 2 toxicity in D. magna that involves the coating of the organism surface with nTiO 2 combined with a molting disruption. Neonate D. magna (≤6 h) exposed to 2 mg/L nTiO 2 exhibited a “biological surface coating” that disappeared within 36 h, during which the first molting was successfully managed by 100% of the exposed organisms. Continued exposure up to 96 h led to a renewed formation of the surface coating and significantly reduced the molting rate to 10%, resulting in 90% mortality. Because coating of aquatic organisms by manmade NP might be ubiquitous in nature, this form of physical NP toxicity might result in widespread negative impacts on environmental health.
    Keywords: Research Article ; Biology ; Chemistry ; Earth Sciences ; Materials Science ; Medicine ; Chemistry ; Public Health And Epidemiology ; Marine And Aquatic Sciences ; Ecology ; Critical Care And Emergency Medicine ; Science Policy ; Biochemistry ; Non-clinical Medicine
    E-ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Biochemical Genetics, 2013, Vol.51(5), pp.406-412
    Description: Byline: Karolina Kolodziej (1), Ivan Nikolov (2), Holger K. Schulz (1), Kathrin Theissinger (1), Ralf Schulz (1) Author Affiliation: (1) Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, D-76829, Landau, Germany (2) Molecular Zoology, Institute of Zoology, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354, Freising, Germany Article History: Registration Date: 12/01/2013 Received Date: 02/05/2012 Accepted Date: 06/09/2012 Online Date: 05/02/2013
    Keywords: Genetic Research -- Methods ; Genetic Research -- Analysis ; Dna -- Methods ; Dna -- Analysis;
    ISSN: 0006-2928
    E-ISSN: 1573-4927
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: FEBS Letters, 20 December 2014, Vol.588(24), pp.4769-4775
    Description: C-X-C motif chemokine 12/C-X-C chemokine receptor type 4 (CXCL12/CXCR4) signaling is involved in ontogenesis, hematopoiesis, immune function and cancer. Recently, the orphan chemokine CXCL14 was reported to inhibit CXCL12-induced chemotaxis – probably by allosteric modulation of CXCR4. We thus examined the effects of CXCL14 on CXCR4 regulation and function using CXCR4-transfected human embryonic kidney (HEK293) cells and Jurkat T cells. CXCL14 did not affect dose–response profiles of CXCL12-induced CXCR4 phosphorylation, G protein-mediated calcium mobilization, dynamic mass redistribution, kinetics of extracellular signal-regulated kinase 1 (ERK1) and ERK2 phosphorylation or CXCR4 internalization. Hence, essential CXCL12-operated functions of CXCR4 are insensitive to CXCL14, suggesting that interactions of CXCL12 and CXCL14 pathways depend on a yet to be identified CXCL14 receptor.
    Keywords: Cxcl12 ; Cxcr4 ; Cxcl14 ; Amd3465 ; Amd3100 ; Dynamic Mass Redistribution ; Cxcr4 Antagonist ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0014-5793
    E-ISSN: 1873-3468
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: FEBS Letters, 19 October 2012, Vol.586(20), pp.3665-3673
    Description: ► lethal Toxin induces expression of the cell death-regulating GTPase RhoB. ► RhoB expression is based on tracscriptional activation and involves p38 MAP kinase. ► RhoB is rapidly degraded in a proteasome- and a caspase-dependent manner. ► RhoB suppresses caspase-3 activation in TcsL-treated cells. Mono-glucosylation of (H/K/N)Ras by lethal toxin (TcsL) blocks critical survival signaling pathways, resulting in apoptosis. In this study, TcsL and K-Ras knock-down by siRNA are presented to result in expression of the cell death-regulating small GTPase RhoB. TcsL-induced RhoB expression is based on transcriptional activation involving p38 MAP kinase. Newly synthesized RhoB protein is rapidly degraded in a proteasome- and a caspase-dependent manner, providing first evidence for caspase-dependent degradation of a Rho family protein. Although often characterised as a pro-apoptotic protein, RhoB suppresses caspase-3 activation in TcsL-treated fibroblasts. The finding on the cytoprotective activity of RhoB in TcsL-treated cells re-enforces the concept that RhoB exhibits cytoprotective rather than pro-apoptotic activity in a cellular background of inactive Ras.
    Keywords: Glucosyltransferase ; Apoptosis ; Caspase ; Proteasome ; P38 Map Kinase ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0014-5793
    E-ISSN: 1873-3468
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Current Opinion in Structural Biology, 2011, Vol.21(2), pp.232-239
    Description: Hallmarks of proteins containing β-helices are their increased stability and rigidity and their aggregation prone folding pathways. While parallel β-helices fold independently, the folding and assembly of many triple β-helices depends on a registration signal in order to adopt the correct three-dimensional structure. In some cases this is a mere trimerization domain, in others specialized chaperones are required. Recently, the crystal structures of two classes of intramolecular chaperones of β-helical proteins have been determined. Both mediate the assembly of large tailspike proteins and release themselves after maturation; however, they differ substantially in their structure and autoproteolytic release mechanisms.
    Keywords: Biology ; Chemistry
    ISSN: 0959-440X
    E-ISSN: 1879-033X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: BBA - Molecular Cell Research, August 2015, Vol.1853(8), pp.1850-1859
    Description: The translocase of the outer mitochondrial membrane (TOM complex) is the general entry gate into mitochondria for almost all imported proteins. A variety of specific receptors allow the TOM complex to recognize targeting signals of various precursor proteins that are transported along different import pathways. Aside from the well-characterized presequence receptors Tom20 and Tom22 a third TOM receptor, Tom70, binds proteins of the carrier family containing multiple transmembrane segments. Here we demonstrate that Tom70 directly binds to presequence peptides using a dedicated groove. A single point mutation in the cavity of this pocket (M551R) reduces the presequence binding affinity of Tom70 ten-fold and selectively impairs import of the presequence-containing precursor Mdl1 but not the ADP/ATP carrier (AAC). Hence Tom70 contributes to the presequence import pathway by recognition of the targeting signal of the Mdl1 precursor.
    Keywords: Tom70 ; Mitochondria ; Protein Import ; Presequence ; Biology ; Chemistry
    ISSN: 0167-4889
    E-ISSN: 1879-2596
    E-ISSN: 18782434
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Journal of Molecular Biology, 2010, Vol.397(1), pp.341-351
    Description: An α-2,8-linked polysialic acid (polySia) capsule confers immune tolerance to neuroinvasive, pathogenic prokaryotes such as K1 and and supports host infection by means of molecular mimicry. Bacteriophages of the K1 family, infecting K1, specifically recognize and degrade this polySia capsule utilizing tailspike endosialidases. While the crystal structure for the catalytic domain of the endosialidase of bacteriophage K1F (endoNF) has been solved, there is yet no structural information on the mode of polySia binding and cleavage available. The crystal structure of activity deficient active-site mutants of the homotrimeric endoNF cocrystallized with oligomeric sialic acid identified three independent polySia binding sites in each endoNF monomer. The bound oligomeric sialic acid displays distinct conformations at each site. In the active site, a Sia molecule is bound in an extended conformation representing the enzyme–product complex. Structural and biochemical data supported by molecular modeling enable to propose a reaction mechanism for polySia cleavage by endoNF.
    Keywords: Polysialic Acid ; Endonf ; Glycosidase ; Host Recognition ; Biology ; Chemistry
    ISSN: 0022-2836
    E-ISSN: 1089-8638
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Biochemical and Biophysical Research Communications, 10 August 2012, Vol.424(4), pp.758-764
    Description: ► We demonstrate substantial antiapoptotic effects of TβMCA on hepatocyte apoptosis. ► TβMCA prevents bile acid-induced breakdown of the mitochondrial membrane potential (MMP). ► TβMCA also restores the MMP when the free fatty acid palmitate is used as a hepatotoxin. β-Muricholic acid (βMCA) is a trihydroxylated bile acid that constitutes the major bile acid in rat and mouse. βMCA is more hydrophilic than ursodeoxycholic acid and has been evaluated for dissolution of cholesterol gallstones. Since it is unknown if βMCA has beneficial effects on hepatocyte cell death we determined the effect of tauro-βMCA (TβMCA) on apoptosis . Human Ntcp-transfected HepG2 cells and primary hepatocytes from rat and mouse were incubated with the proapoptotic glycochenodeoxycholic acid (GCDCA) as well as the free fatty acid palmitate in the absence and presence of TβMCA. Apoptosis was quantified using caspase 3/7-assays and after Hoechst 33342 staining. The mitochondrial membrane potential (MMP) was measured fluorometrically using JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-benzimidazol-carbocyaniniodide). Immunoblotting was performed against the proapoptotic Bcl-2-protein Bax. In Ntcp-HepG2 cells, GCDCA markedly increased apoptosis after 4 h. Co-incubation with TβMCA reduced apoptosis to 49% ( 〈 0.01 vs. GCDCA, each; = 6). While GCDCA (100 μmol/L) reduced the MMP to 34% after 6 h, combination treatment with TβMCA restored the MMP to control levels at all time points ( = 4). TβMCA also restored breakdown of the MMP induced by palmitate. GCDCA induced a translocation of Bax from the cytosol to mitochondria that was inhibited by simultaneous treatment with TβMCA in eqimolar concentrations. TβMCA restricts hepatocellular apoptosis induced by low micromolar concentrations of GCDCA or palmitate via inhibition of Bax translocation to mitochondria and preservation of the MMP. Thus, further studies are warranted to evaluate a potential use of TβMCA in ameliorating liver injury in cholestasis.
    Keywords: Cholestasis ; Bile Acid ; Apoptosis ; Mitochondrial Membrane Potential ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0006-291X
    E-ISSN: 1090-2104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: EMBO Journal, 18 August 2004, Vol.23(16), pp.3282-3289
    Description: Morphine is a poor inducer of μ‐opioid receptor (MOR) internalization, but a potent inducer of cellular tolerance. Here we show that, in contrast to full agonists such as [‐Ala‐MePhe‐Gly‐ol]enkephalin (DAMGO), morphine stimulated a selective phosphorylation of the carboxy‐terminal residue 375 (Ser). Ser phosphorylation was sufficient and required for morphine‐induced desensitization of MOR. In the presence of full agonists, morphine revealed partial agonistic properties and potently inhibited MOR phosphorylation and internalization. Upon removal of the drug, DAMGO‐desensitized receptors were rapidly dephosphorylated. In contrast, morphine‐desensitized receptors remained at the plasma membrane in a Ser‐phosphorylated state for prolonged periods. Thus, morphine promotes terminal MOR desensitization by inducing a persistent modification of Ser.
    Keywords: Desensitization ; Morphine ; Opioid Receptor ; Phosphorylation ; Tolerance
    ISSN: 0261-4189
    E-ISSN: 1460-2075
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Cellular Physiology and Biochemistry, August 2011, Vol.28(2), pp.185-198
    Description: Extracellular matrix proteins, adhesion molecules, and cytoskeletal proteins form a dynamic network interacting with signalling molecules as an adaptive response to altered gravity. An important issue is the exact differentiation between real microgravity responses of the cells or cellular reactions to hypergravity and/or vibrations. To determine the effects of real microgravity on human cells, we used four DLR parabolic flight campaigns and focused on the effects of short-term microgravity (22 s), hypergravity (1.8 g), and vibrations on ML-1 thyroid cancer cells. No signs of apoptosis or necrosis were detectable. Gene array analysis revealed 2430 significantly changed transcripts. After 22 s microgravity, the F-actin and cytokeratin cytoskeleton was altered, and ACTB and KRT80 mRNAs were significantly upregulated after the first and thirty-first parabolas. The COL4A5 mRNA was downregulated under microgravity, whereas OPN and FN were significantly upregulated. Hypergravity and vibrations did not change ACTB, KRT-80 or COL4A5 mRNA. MTSS1 and LIMA1 mRNAs were downregulated/slightly upregulated under microgravity, upregulated in hypergravity and unchanged by vibrations. These data indicate that the graviresponse of ML-1 cells occurred very early, within the first few seconds. Downregulated MTSS1 and upregulated LIMA1 may be an adaptive mechanism of human cells for stabilizing the cytoskeleton under microgravity conditions.
    Keywords: Original Paper ; Thyroid Cancer ; Extracellular Matrix ; Apoptosis ; Cytoskeleton ; Weightlessness ; Microgravity ; Hypergravity ; Vibration ; Biology ; Chemistry
    ISSN: 1015-8987
    E-ISSN: 1421-9778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages