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  • 1
    Electronic Resource
    Electronic Resource
    Differential modulation of Ih by 5-HT receptors in mouse CA1 hippocampal neurons (2002)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 16 (2002), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: CA1 pyramidal neurons of the hippocampus express various types of serotonin (5-HT) receptors, such as 5-HT1A, 5-HT4 and 5-HT7 receptors, which couple to Gαi or Gαs proteins and operate on different intracellular signalling pathways. In the present paper we verify such differential serotonergic modulation for the hyperpolarization-activated current Ih. Activation of 5-HT1A receptors induced an augmentation of current-induced hyperpolarization responses, while the responses declined after 5-HT4 receptors were activated. The resting potential of neurons hyperpolarized (−2.3 ± 0.7 mV) after 5-HT1A receptor activation, activation of 5-HT4 receptors depolarized neurons (+3.3 ± 1.4 mV). Direct activation of adenylyl cyclase (AC) by forskolin also produced a depolarization. In voltage clamp, the Ih current was identified by its characteristic voltage- and time-dependency and by blockade with CsCl or ZD7288. Activation of 5-HT1A receptors reduced Ih and shifted the activation curve to a more negative voltage by −5 mV at half-maximal activation. Activation of 5-HT4 and 5-HT7 receptors increased Ih and shifted the activation curve to the right by +5 mV. Specific activation of 5-HT4 receptors by BIMU8 increased membrane conductance and showed an increase in Ih in a subset of cells, but did not induce a significant alteration in the activation curve. In order to verify spatial differences, we applied BIMU8 selectively to the soma and to the dendrites. Only somatic application induced receptor activation. These data are confirmed by immunofluorescence stainings with an antibody against the 5-HT4A receptor, revealing receptor expression at the somata of the CA1 region. A similar expression pattern was found with a new antibody against 5-HT7 receptors which reveals immunofluorescence staining on the cell bodies of pyramidal neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2002.02072.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of inorganic mercury (Hg2+) on calcium channel currents and catecholamine release from bovine chromaffin cells (1995)
    Springer
    Archives of toxicology 69 (1995), S. 191-196 
    Details
    ISSN: 1432-0738
    Keywords: Key words Inorganic mercury ; Bovine chromaffin cells ; Calcium channels ; Catecholamine release ; Cadmium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of inorganic mercury (Hg2+) on calcium channel currents and the potassium-evoked catecholamine release of bovine chromaffin cells in culture were examined. The effects of cadmium (Cd2+), known to block calcium channels and reduce catecholamine release of chromaffin cells, were studied for comparison. Calcium channel currents were recorded in the whole-cell configuration of the patch-clamp technique. Hg2+ is a potent calcium channel blocker in bovine chromaffin cells. The IC50 value is about 3 μM, the Hill slope 1.46. In a concentration of 100 μM, Hg2+ blocked the currents completely; 100 μM Cd2+ had the same effect. Potassium-evoked catecholamine release from chromaffin cells was measured at different timepoints with high-performance-liquid-chromatography (HPLC) under control conditions and in the presence of different Hg2+ concentrations. Low Hg2+ concentrations (0.1 and 1 μM) did not affect the amount of the catecholamines epinephrine (E) and norepinephrine (NE) which was released. Under identical conditions 1 μM Cd2+ also had no effect on release. With 10 μM Hg2+ there was a time-dependent increase in the potassium-evoked catecholamine release (by 27% after 8 min). The E/NE ratio was not altered, suggesting that the release of both hormones was increased similarly. In contrast to this, the release was slightly reduced with 10 μM Cd2+. In the presence of 100 μM Hg2+, there was a reduction of the release during an early phase, followed by an increase. The reduction is most probably due to the fast and effective calcium channel block by Hg2+ in this high concentration. The calcium channel block by 100 μM Cd2+ also reduced the release significantly. Catecholamine release of bovine chromaffin cells is driven into two opposite directions by Hg2+. On the one hand, a calcium channel block reduces the release, while on the other hand effects occur which can increase the release. Both tendencies occur simultaneously, but have different concentration- and time- dependencies; therefore one can overcome the other under specific conditions. The catecholamine output at a given timepoint reflects the “sum” of these different effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050157
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of deltamethrin on catecholamine secretion of bovine chromaffin cells (1994)
    Springer
    Archives of toxicology 68 (1994), S. 532-534 
    Details
    ISSN: 1432-0738
    Keywords: Key words: Pyrethroids – Deltamethrin – Bovine chromaffin cells – HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The effects of the pyrethroid deltamethrin (D) on catecholamine secretion of cultured bovine chromaffin cells were investigated in vitro using high performance liquid chromatography (HPLC). Spontaneous release of catecholamines was increased by 10 μM and 100 μM D. This increase could partially be prevented by the simultaneous use of 2 μM tetrodotoxin (TTX), which reduced the increase by 10 μM D of catecholamine secretion by 90% and that of 100 μM D by 50%. TTX 2 μM alone did not alter the spontaneous release in comparison to controls. Medullary chromaffin cells consist of two cell groups, one secreting mainly epinephrine (E), the other norepinephrine (NE). The ratio between the spontaneously secreted catecholamines E and NE was increased after treatment with D, indicating a dominant effect on E secreting cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050109
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  • 4
    Electronic Resource
    Electronic Resource
    Congener specific effects by polychlorinated biphenyls on catecholamine content and release in chromaffin cells (1997)
    Springer
    Archives of toxicology 71 (1997), S. 416-421 
    Details
    ISSN: 1432-0738
    Keywords: Key words Polychlorinated biphenyls  ;  Neurotoxicity  ;  Catecholamine release  ;  In vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of the non-planar polychlorinated biphenyl (PCB) congener 2,2′,4,4′-tetrachlorobiphenyl (2,4-TCB) and of the coplanar PCB congener 3,3′,4,4′-tetrachlorobiphenyl (3,4-TCB) were investigated on the catecholamine content and release from bovine adrenal chromaffin cells in culture. Each congener was tested at three concentrations (20, 50 and 100 μM) and two exposure periods (24 h and 5 days). Catecholamine release induced by K+-stimulation as well as catecholamine content of Triton X-100 treated cell cultures were examined using high-performance liquid chromatography (HPLC). 2,4-TCB showed dose- and time-dependent effects. 2,4-TCB at 100 μM reduced the K+-stimulated catecholamine release after 24 h of exposure. After 5 days of exposure, 2,4 TCB at 50 and 100 μM drastically reduced the K+-stimulated catecholamine release. 3,4-TCB even at a concentration of 100 μM over exposure of either 24 h or 5 days had no effects on the K+-stimulated secretion. When chromaffin cells, exposed to 2,4-TCB, were lysed with 0.5% Triton X-100, a dose- and time-dependent reduction of the catecholamine content appeared. The 3,4-TCB did not reduce the catecholamine content. Conversely there seemed to be a trend towards an increase in catecholamine content. Spontaneous release of catecholamines was strongly increased by the non-planar 2,4 TCB, while the coplanar 3,4 TCB showed no effects on this parameter. Furthermore, the effects of 2,4 TCB appeared to be reversible after replacing the highest concentration (100 μM) of the TCB-solution with culture-medium at the end of the 24-h exposure. Thus, K+-stimulated catecholamine release and the catecholamine content of bovine adrenal chromaffin cells was effectively reduced by the non-planar PCB congener whereas spontaneous catecholamine release was strongly increased. The coplanar PCB congener was ineffective at the same conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050405
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  • 5
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    CHEMSEA Findings (2014)
    Institute of Oceanology Polish Academy of Sciences
    In:  EPIC3Gdańsk, Institute of Oceanology Polish Academy of Sciences, 86 p., ISBN: 978-83-936609-1-9
    Details
    Publication Date: 2014-06-23
    Repository Name: EPIC Alfred Wegener Institut
    Type: Book , peerRev
    Format: application/pdf
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  • 6
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    The toxicity of chemical warfare mixtures on the Baltic mussel Mytilus trossulus (2014)
    In:  EPIC3SETAC 24th Annual Meeting, Basel, Switzerland, 2014-05-11-2014-05-15
    Details
    Publication Date: 2014-05-20
    Description: After the World War II, approx. 40.000 tonnes of chemical munitions containing about 13.000 tonnes of chemical warfare agents (CWAs) were dumped in the Baltic Sea [1]. As the artillery shells, aircraft bombs and containers are corroding, the contents are leaking into the environment contaminating the surrounding sediments but also spreading far beyond the dumpsite boundaries [2]. Thus, the necessity of investigations on the impact of chemical warfare on biota, such as inorganic arsenic and organo-arsenic compounds, is increasing. Among the dumped CWAs are the vesicant mustard gas (Bis(2-chloroethyl)sulfide), the tear gas chloroacetophenone (2-Chloro-1-phenylethanone) as well as the irritants Clark I (Diphenylarsinechloride) and Adamsite (10-Chloro-5-hydrophenarsazine(10)) [3]. Persistent contaminations at dumping sites are mostly related to arsenic containing compounds [2]. Thus, arsenic containing CWAs have been chosen as model CWAs in the present study. Here, we present the first approach to investigate biological effects of CWA mixtures on the health of blue mussels (M. trossulus) under laboratory conditions. The evaluation of the health status was based on a great array of biomarkers encompassing immunocompetence, oxidative stress defence and pathological alterations in different tissues. Chemical analysis of tissue and water samples facilitated an integrated assessment.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 7
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    Spatial compartmentalization of free radical formation and mitochondrial heterogeneity in bivalve gills revealed by live-imaging techniques (2016)
    BIOMED CENTRAL LTD
    In:  EPIC3Frontiers in Zoology, BIOMED CENTRAL LTD, 13(1), pp. 1, ISSN: 1742-9994
    Details
    Publication Date: 2016-08-10
    Description: Background Reactive oxygen (ROS) and nitrogen (RNS) species are produced during normal unstressed metabolic activity in aerobic tissues. Most analytical work uses tissue homogenates, and lacks spatial information on the tissue specific sites of actual ROS formation. Live-imaging techniques (LIT) utilize target-specific fluorescent dyes to visualize biochemical processes at cellular level. Results Together with oxidative stress measurements, here we report application of LIT to bivalve gills for ex-vivo analysis of gill physiology and mapping of ROS and RNS formation in the living tissue. Our results indicate that a) mitochondria located in the basal parts of the epithelial cells close to the blood vessels are hyperpolarized with high Δψm, whereas b) the peripheral mitochondria close to the cilia have low (depolarized) Δψm. These mitochondria are densely packed (mitotracker Deep Red 633 staining), have acidic pH (Ageladine-A) and collocate with high formation of nitric oxide (DAF-2DA staining). NO formation is also observed in the endothelial cells surrounding the filament blood sinus. ROS (namely H2O2, HOO• and ONOO− radicals, assessed through C-H2DFFDA staining) are mainly formed within the blood sinus of the filaments and are likely to be produced by hemocytes as defense against invading pathogens. On the ventral bend of the gills, subepithelial mucus glands contain large mucous vacuoles showing higher fluorescence intensities for O2 •- than the rest of the tissue. Whether this O2 •- production is instrumental to mucus formation or serves antimicrobial protection of the gill surface is unknown. Cells of the ventral bends contain the superoxide forming mucocytes and show significantly higher protein carbonyl formation than the rest of the gill tissue. Conclusions In summary, ROS and RNS formation is highly compartmentalized in bivalve gills under unstressed conditions. The main mechanisms are the differentiation of mitochondria membrane potential and basal ROS formation in inner and outer filament layers, as well as potentially antimicrobial ROS formation in the central blood vessel. Our results provide new insight into this subject and highlight the fact that studying ROS formation in tissue homogenates may not be adequate to understand the underlying mechanism in complex tissues.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Toxicity of the TNT derivatives 2-ADNT and 4-ADNT on the marine flatworm Macrostomum lignano raised in the laboratory (2018)
    In:  EPIC3International Symposium for sea-dumped munition and UXO, Schleswig-Holstein's Representation to the German Federal Government, In den Ministergärten 8, 10117 Berlin, 2018-05-02-2018-05-04
    Details
    Publication Date: 2018-05-29
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 9
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    Enhancement of photosynthesis in Synechococcus bacillaris by sponge-derived Ageladine A (2019)
    PUBLIC LIBRARY SCIENCE
    In:  EPIC3PLoS ONE, PUBLIC LIBRARY SCIENCE, 14(e02137), ISSN: 1932-6203
    Details
    Publication Date: 2019-03-28
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
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    An aerobic eukaryotic parasite with functional mitochondria that likely lacks a mitochondrial genome (2019)
    American Association for the Advancement of Science
    In:  EPIC3Science Advances, American Association for the Advancement of Science, 5(4), ISSN: 2375-2548
    Details
    Publication Date: 2020-02-12
    Description: Dinoflagellates are microbial eukaryotes that have exceptionally large nuclear genomes; however, their organelle genomes are small and fragmented and contain fewer genes than those of other eukaryotes. The genus Amoebophrya (Syndiniales) comprises endoparasites with high genetic diversity that can infect other dinoflagellates, such as those forming harmful algal blooms (e.g., Alexandrium). We sequenced the genome (~100 Mb) of Amoebophrya ceratii to investigate the early evolution of genomic characters in dinoflagellates. The A. ceratii genome encodes almost all essential biosynthetic pathways for self-sustaining cellular metabolism, suggesting a limited dependency on its host. Although dinoflagellates are thought to have descended from a photosynthetic ancestor, A. ceratii appears to have completely lost its plastid and nearly all genes of plastid origin. Functional mitochondria persist in all life stages of A. ceratii, but we found no evidence for the presence of a mitochondrial genome. Instead, all mitochondrial proteins appear to be lost or encoded in the A. ceratii nucleus.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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