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51.
Oxygen minimum zones (OMZs) affect distribution patterns, community structure and metabolic processes of marine organisms. Due to the prominent role of zooplankton, especially copepods, in the marine carbon cycle and the predicted intensification and expansion of OMZs, it is essential to understand the effects of hypoxia on zooplankton distribution and ecophysiology. For this study, calanoid copepods were sampled from different depths (0–1800 m) at eight stations in the eastern tropical Atlantic (3°47′N to 18°S) during three expeditions in 2010 and 2011. Their horizontal and vertical distribution was determined and related to the extent and intensity of the OMZ, which increased from north to south with minimum O2 concentrations (12.7 µmol kg−1) in the southern Angola Gyre. Calanoid copepod abundance was highest in the northeastern Angola Basin and decreased towards equatorial regions as well as with increasing depth. Maximum copepod biodiversity was observed in the deep waters of the central Angola Basin. Respiration rates and enzyme activities were measured to reveal species-specific physiological adaptations. Enzyme activities of the electron transport system (ETS) and lactate dehydrogenase (LDH) served as proxies for aerobic and anaerobic metabolic activity, respectively. Mass-specific respiration rates and ETS activities decreased with depth of occurrence, consistent with vertical changes in copepod body mass and ambient temperature. Copepods of the families Eucalanidae and Metridinidae dominated within the OMZ. Several of these species showed adaptive characteristics such as lower metabolic rates, additional anaerobic activity and diel vertical migration that enable them to successfully inhabit hypoxic zones. 相似文献
52.
Claudia Siegl Patricia Hamminger Herbert Jank Uwe Ahting Benedikt Bader Adrian Danek Allison Gregory Monika Hartig Susan Hayflick Andreas Hermann Holger Prokisch Esther M. Sammler Zuhal Yapici Rainer Prohaska Ulrich Salzer 《PloS one》2013,8(10)
Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington’s disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an “acanthocytic state” of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration. 相似文献
53.
Alex F?rster Hans Ulrich Kerl Holger Wenz Marc A. Brockmann Ingo N?lte Christoph Groden 《PloS one》2013,8(10)
Purpose
Characterization of lacunar infarction (LI) by use of multimodal MRI including diffusion- and perfusion-weighted imaging (DWI, PWI) is difficult because of the small lesion size. Only a few studies evaluated PWI in LI and the results are inconsistent.Methods
In 16 LI patients who underwent initial MRI within 6 hours after symptom onset and follow-up MRI within 1 week demographics, clinical presentation, and MRI findings were analyzed with special emphasis on DWI and PWI findings. Time to peak maps were classified as showing a normal perfusion pattern or areas of hypoperfusion which were further categorized in mismatch (PWI>DWI), inverse mismatch (PWI<DWI), and match (PWI=DWI). Quantitative perfusion maps were generated and analyzed by use of Signal Processing in NMR-Software (SPIN).Results
Of the 16 patients (mean age 65.5±12.9 years), 14 (87.5%) were male. Clinical symptoms comprised dysarthria (50%), hemiparesis (81.3%), and hemihypaesthesia (18.8%). Intravenous thrombolysis was performed in 7 (43.8%) patients. Clinical improvement was observed in 12 patients (75 %), while 2 (12.5%) patients showed a deterioration and another 2 (12.5%) a stable course. Acute ischemic lesions (mean volume of 0.46±0.29 cm3) were located in the thalamus (n=8, 50%), internal capsule (n=4, 25%), corona Radiata (n=3, 18.8%) and the mesencephalon (n=1, 6.3%). Circumscribed hypoperfusion (mean volume 0.61±0.48 cm3) was evident in 10 (62.5%) patients. Of these, 3 patients demonstrated a match, 4 an inverse mismatch, and 3 a mismatch between DWI and PWI lesion. Mean CBF and CBV ratios were 0.65±0.28 and 0.84±0.41 respectively. Growth of DWI lesions was observed in 7 (43.8%) and reversal of DWI lesions in 3 (18.8%) patients.Conclusions
MRI allows identification of different DWI and PWI patterns in LI, including growth and reversal of ischemic lesions. Consequently, it may serve for a better characterization of this stroke subtype and support treatment decisions in daily clinical practice. 相似文献54.
55.
Holger Winter Yosuke Maeda Hiroaki Mitsuya Jiri Zemlicka 《Nucleosides, nucleotides & nucleic acids》2013,32(7-9):1341-1345
Abstract Lipophilic phosphodiester L-alaninates of acyclic unsaturated nucleoside analogues 1d, 1e, 2d, 2e, 3d, 3e, 4d and 5d were prepared and their antiretroviral activity was examined in ATH8 cell culture infected with HIV-1. A possible mechanism of action of these analogues is discussed. 相似文献
56.
In budding yeast, the meiosis-specific protein kinase Ime2 is required for normal meiotic progression.Current evidence suggests that Ime2 is functionally related to Cdc28, the major cyclin-dependent kinase in yeastthat is essential for both cell cycle and meiosis. We have previously reported that a natural target of Ime2 activityis replication protein A (RPA), the cellular single-stranded DNA-binding protein that performs critical functionsduring DNA replication, repair, and recombination. Ime2-dependent RPA phosphorylation first occursearly in meiosis and targets the middle subunit of the RPA heterotrimeric complex (Rfa2). We now demonstratethat Rfa2 serine 27 (S27) is required for Ime2-dependent Rfa2 phosphorylation in vivo. S27 is also required forRfa2 phosphorylation in vitro catalyzed by immunoprecipitated Ime2. In addition, Ime2 mediates in vitro phosphorylationof a short peptide containing Rfa2 amino acids 23 through 29, thereby providing evidence that S27itself is the phosphoacceptor. Phosphorylation site mapping supports this conclusion, as mass spectrometryanalysis has revealed that at least three residues within Rfa2 amino acids 2 through 35 become phosphorylatedspecifically during meiosis. Although S27 is embedded in a motif that is recognized by several protein kinases,this sequence is not a typical target of cyclin-dependent kinases. Therefore, the mechanism underlying Ime2substrate recognition could differ from that of Cdc28. 相似文献
57.
58.
The breakage or distortion of cellular structures is one of the biggest problems in creating micro-sections for wood anatomical analyses in tree-ring as well as other branches of anatomical research. These broken or distorted structures cause artifacts in photomicrographs that require time consuming image manipulation or corrections prior to further analyses. The simple application of a cornstarch, water, and glycerol (CWG) solution (10:8:7 ratio), a so called non-Newtonian fluid to the surface of wooden specimen before sectioning improves the overall quality of the resulting micro-sections. In particular the problem of secondary cell walls splitting off the primary wall while sectioning is drastically reduced. The quality of the sections using this solution is comparable to that obtained from the more laborious and expensive paraffin embedding. 相似文献
59.
Mathias Weber Alexandra R. Wey-Fabrizius Lars Podsiadlowski Alexander Witek Ralph O. Schill László Sugár Holger Herlyn Thomas Hankeln 《Molecular phylogenetics and evolution》2013,66(1):182-189
The metazoan taxon Syndermata (Monogononta, Bdelloidea, Seisonidea, Acanthocephala) comprises species with vastly different lifestyles. The focus of this study is on the phylogeny within the syndermatan subtaxon Acanthocephala (thorny-headed worms, obligate endoparasites). In order to investigate the controversially discussed phylogenetic relationships of acanthocephalan subtaxa we have sequenced the mitochondrial (mt) genomes of Echinorhynchus truttae (Palaeacanthocephala), Paratenuisentis ambiguus (Eoacanthocephala), Macracanthorhynchus hirudinaceus (Archiacanthocephala), and Philodina citrina (Bdelloidea). In doing so, we present the largest molecular phylogenetic dataset so far for this question comprising all major subgroups of Acanthocephala. Alongside with publicly available mt genome data of four additional syndermatans as well as 18 other lophotrochozoan (spiralian) taxa and one outgroup representative, the derived protein-coding sequences were used for Maximum Likelihood as well as Bayesian phylogenetic analyses. We achieved entirely congruent results, whereupon monophyletic Archiacanthocephala represent the sister taxon of a clade comprising Eoacanthocephala and monophyletic Palaeacanthocephala (Echinorhynchida). This topology suggests the secondary loss of lateral sensory organs (sensory pores) within Palaeacanthocephala and is further in line with the emergence of apical sensory organs in the stem lineage of Archiacanthocephala. 相似文献
60.
Holger Hackstein Sabine Kranz Anne Lippitsch Andreas Wachtendorf Olivia Kershaw Achim D Gruber Gabriela Michel Jürgen Lohmeyer Gregor Bein Nelli Baal Susanne Herold 《Respiratory research》2013,14(1):91