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101.
102.
Mass migration of desert locusts is a common phenomenon in North Africa and the Middle East but how these insects navigate is still poorly understood. Laboratory studies suggest that locusts are able to exploit the sky polarization pattern as a navigational cue. Like other insects locusts detect polarized light through a specialized dorsal rim area (DRA) of the eye. Polarization signals are transmitted through the optic lobe to the anterior optic tubercle (AOTu) and, finally, to the central complex in the brain. Whereas neurons of the AOTu integrate sky polarization and chromatic cues in a daytime dependent manner, the central complex holds a topographic representation of azimuthal directions suggesting a role as an internal sky compass. To understand further the integration of sky compass cues we studied polarization-sensitive (POL) neurons in the medulla that may be intercalated between DRA photoreceptors and AOTu neurons. Five types of POL-neuron were characterized and four of these in multiple recordings. All neurons had wide arborizations in medulla layer 4 and most, additionally, in the dorsal rim area of the medulla and in the accessory medulla, the presumed circadian clock. The neurons showed type-specific orientational tuning to zenithal polarized light and azimuth tuning to unpolarized green and UV light spots. In contrast to neurons of the AOTu, we found no evidence for color opponency and daytime dependent adjustment of sky compass signals. Therefore, medulla layer 4 is a distinct stage in the integration of sky compass signals that precedes the time-compensated integration of celestial cues in the AOTu. 相似文献
103.
Mayr JA Freisinger P Schlachter K Rolinski B Zimmermann FA Scheffner T Haack TB Koch J Ahting U Prokisch H Sperl W 《American journal of human genetics》2011,(6):806-812
Thiamine pyrophosphate (TPP) is an essential cofactor of the cytosolic transketolase and of three mitochondrial enzymes involved in the oxidative decarboxylation of either pyruvate, α-ketoglutarate or branched chain amino acids. Thiamine is taken up by specific transporters into the cell and converted to the active TPP by thiamine pyrophosphokinase (TPK) in the cytosol from where it can be transported into mitochondria. Here, we report five individuals from three families presenting with variable degrees of ataxia, psychomotor retardation, progressive dystonia, and lactic acidosis. Investigation of the mitochondrial energy metabolism showed reduced oxidation of pyruvate but normal pyruvate dehydrogenase complex activity in the presence of excess TPP. A reduced concentration of TPP was found in the muscle and blood. Mutation analysis of TPK1 uncovered three missense, one splice-site, and one frameshift mutation resulting in decreased TPK protein levels. 相似文献
104.
Kallnik V Schulz C Schultz C Schweiger P Deppenmeier U 《Applied microbiology and biotechnology》2011,90(4):1285-1293
The first hyperthermophilic d-arabitol dehydrogenase from Thermotoga maritima was heterologously purified from Escherichia coli. The protein was purified with and without a Strep-tag. The enzyme exclusively catalyzed the NAD(H)-dependent oxidoreduction of d-arabitol, d-xylitol, d-ribulose, or d-xylulose. A twofold increase of catalytic rates was observed upon addition of Mg2+ or K+. Interestingly, only the tag-less protein was thermostable, retaining 90% of its activity after 90 min at 85 °C. However,
the tag-less form of d-arabitol dehydrogenase had similar kinetic parameters compared to the tagged enzyme, demonstrating that the Strep-tag was not deleterious to protein function but decreased protein stability. A single band at 27.6 kDa was observed on SDS-PAGE
and native PAGE revealed that the protein formed a homohexamer and a homododecamer. The enzyme catalyzed oxidation of d-arabitol to d-ribulose and therefore belongs to the class of d-arabitol 2-dehydrogenases, which are typically observed in yeast and not bacteria. The product d-ribulose is a rare ketopentose sugar that has numerous industrially applications. Given its thermostability and specificity,
d-arabitol 2-dehydrogenase is a desirable biocatalyst for the production of rare sugar precursors. 相似文献
105.
Theresa Ohlig Do Viet Le Andreas Gardemann Carmen Wolke Sarah Gürtler Daniela Peter Lorenz Schild Uwe Lendeckel 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2018,1863(4):379-387
The mitochondrial phospholipid cardiolipin (CL) has been implicated with mitochondrial morphology, function, and cell proliferation. Changes in CL are often paralleled by changes in the lipid environment of mitochondria that may contribute to mitochondrial function and proliferation. This study aimed to separate the effects of CL content and CL composition from cellular free fatty acid distribution on bioenergetics and proliferation in C6 glioma cells. To this end, cardiolipin synthase and the CL remodelling enzyme, tafazzin, were knocked-down by siRNA in C6 cells. After 72?h of cultivation, we analysed CL composition by means of LC/MS/MS, distribution of cellular fatty acids by means of gas chromatography, and determined oxygen consumption and proliferation. Knock-down of cardiolipin synthase affected the cellular CL content in the presence of linoleic acid (LA) in the culture medium. Knock-down of tafazzin had no consequence with respect to the pattern of cellular fatty acids but caused a decrease in cell proliferation. It significantly changed the distribution of molecular CL species, increased CL content, decreased oxygen consumption, and decreased cell proliferation when cultured in the presence of linoleic acid (LA). The addition of linoleic acid to the culture medium caused significant changes in the pattern of cellular fatty acids and the composition of molecular CL species. These data suggest that tafazzin is required for efficient bioenergetics and for proliferation of glioma cells. Supplementation of fatty acids can be a powerful tool to direct specific changes in these parameters. 相似文献
106.
107.
Purpose
Although dysphonia has been shown to be a common sign of Huntington disease (HD), the extent of phonatory dysfunction in gene positive premanifest HD individuals remains unknown. The aim of the current study was to explore the possible occurrence of phonatory abnormalities in prodromal HD.Method
Sustained vowel phonations were acquired from 28 premanifest HD individuals and 28 healthy controls of comparable age. Data were analysed acoustically for measures of several phonatory dimensions including airflow insufficiency, aperiodicity, irregular vibration of vocal folds, signal perturbations, increased noise, vocal tremor and articulation deficiency. A predictive model was built to find the best combination of acoustic features and estimate sensitivity/specificity for differentiation between premanifest HD subjects and controls. The extent of voice deficits according to a specific phonatory dimension was determined using statistical decision making theory. The results were correlated to global motor function, cognitive score, disease burden score and estimated years to disease onset.Results
Measures of aperiodicity and increased noise were able to significantly differentiate between premanifest HD individuals and controls (p<0.01). The combination of these aspects of dysphonia led to a sensitivity of 91.5% and specificity of 79.2% to correctly distinguish speakers with premanifest HD from healthy individuals. Some form of disrupted phonatory function was revealed in 68% of our premanifest HD subjects, where 18% had one affected phonatory dimension and 50% showed impairment of two or more dimensions. A relationship between pitch control and cognitive score was also observed (r = −0.50, p = 0.007).Conclusions
Phonatory abnormalities are detectable even the in premotor stages of HD. Speech investigation may have the potential to provide functional biomarkers of HD and could be included in future clinical trials and therapeutic interventions. 相似文献108.
While it is well established that the shapes and sizes of shells are strongly phylogenetically controlled, little is known about the phylogenetic constraints on shell thickness. Yet, shell thickness is likely to be sensitive to environmental fluctuations and has the potential to illuminate environmental perturbations through deep time. Here we systematically quantify the thickness of the anterior brachiopod shell which protects the filtration chamber and is thus considered functionally homologous across higher taxa of brachiopods. Our data come from 66 genera and 10 different orders and shows well-defined upper and lower boundaries of anterior shell thickness. For Ordovician and Silurian brachiopods we find significant order-level differences and a trend of increasing shell thickness with water depth. Modern (Cenozoic) brachiopods, by comparison, fall into the lower half of observed shell thicknesses. Among Ordovician–Silurian brachiopods, older stocks commonly have thicker shells, and thick-shelled taxa contributed more prominently to the Great Ordovician Biodiversification but suffered more severely during the Late Ordovician Mass Extinction. Our data highlight a significant reduction in maximum and minimum shell thickness following the Late Ordovician mass extinction. This points towards stronger selection pressure for energy-efficient shell secretion during times of crisis. 相似文献
109.
Markus K Muellner Barbara Mair Yasir Ibrahim Claudia Kerzendorfer Hannelore Lechtermann Claudia Trefzer Freya Klepsch André C Müller Ernestine Leitner Sabine Macho‐Maschler Giulio Superti‐Furga Keiryn L Bennett José Baselga Uwe Rix Stefan Kubicek Jacques Colinge Violeta Serra Sebastian MB Nijman 《Molecular systems biology》2015,11(2)
110.
Johannes Ehler Sebastian Koball Martin Sauer Steffen Mitzner Heiko Hickstein Reiner Benecke Uwe K. Zettl 《PloS one》2015,10(8)