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  • 1
    Language: English
    In: Science (New York, N.Y.), 19 December 2014, Vol.346(6216), pp.1456-7
    Description: How do electric fields affect enzymatic processes? Binding and crystallographic studies have shown that electrostatic interactions are important in the substrate-binding step that initiates enzyme catalysis. However, for the subsequent steps, experimental data have been limited. The study of electric field effects on the transition state was therefore largely restricted to theory (1). On page 1510 of this issue, Fried et al. (2) use a recently developed technique to quantify the electrostatic contribution to the ratelimiting step of an enzymatic reaction. They show that the local electric field accelerates the reaction, a finding that is likely to apply to other catalytic reactions.
    Keywords: Static Electricity ; Ketosteroids -- Metabolism ; Steroid Isomerases -- Chemistry
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    Language: English
    In: Neuron, 20 August 2014, Vol.83(4), pp.805-822
    Description: Mutations of are associated with nephronophthisis and Bardet-Biedl syndrome, as well as schizophrenia; however, the function of SDCCAG8 remains largely unknown. Here, we show that SDCCAG8 regulates centrosomal accumulation of pericentriolar material and neuronal polarization and migration in the developing mouse cortex. expression is selectively elevated in newborn neurons prior to their commencement of radial locomotion, and suppression of this expression by short-hairpin RNAs or a loss-of-function allele impairs centrosomal recruitment of γ-tubulin and pericentrin, interferes with microtubule organization, decouples the centrosome and the nucleus, and disrupts neuronal migration. Moreover, SDCCAG8 interacts and cotraffics with pericentriolar material 1 (PCM1), a centriolar satellite protein crucial for targeting proteins to the centrosome. Expression of SDCCAG8 carrying a human mutation causes neuronal migration defects. These results reveal a critical role for SDCCAG8 in controlling centrosomal properties and function, and provide insights into the basis of neurological defects linked to mutations. Mutations of are linked with nephronophthisis and Bardet-Biedl syndrome, as well as schizophrenia and mental retardation. Insolera et al. demonstrate that SDCCAG8 regulates centrosomal properties and cortical neuronal migration.
    Keywords: Biology ; Anatomy & Physiology
    ISSN: 0896-6273
    E-ISSN: 1097-4199
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  • 3
    Language: English
    In: Biophysical Journal, 16 February 2016, Vol.110(3), pp.194a-194a
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.bpj.2015.11.1083 Byline: Soren Preus, Lasse Lava Hildebrandt, Victoria Birkedal Author Affiliation: Aarhus University, Aarhus, Denmark Article Note: (miscellaneous) 970-Plat
    Keywords: Biology
    ISSN: 0006-3495
    E-ISSN: 1542-0086
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  • 4
    Language: English
    In: Biophysical Journal, 20 September 2016, Vol.111(6), pp.1278-1286
    Description: Single-molecule total internal reflection fluorescence (TIRF) microscopy constitutes an umbrella of powerful tools that facilitate direct observation of the biophysical properties, population heterogeneities, and interactions of single biomolecules without the need for ensemble synchronization. Due to the low signal/noise ratio in single-molecule TIRF microscopy experiments, it is important to determine the local background intensity, especially when the fluorescence intensity of the molecule is used quantitatively. Here we compare and evaluate the performance of different aperture-based background estimators used particularly in single-molecule Förster resonance energy transfer. We introduce the general concept of multiaperture signatures and use this technique to demonstrate how the choice of background can affect the measured fluorescence signal considerably. A new, to our knowledge, and simple background estimator is proposed, called the local statistical percentile (LSP). We show that the LSP background estimator performs as well as current background estimators at low molecular densities and significantly better in regions of high molecular densities. The LSP background estimator is thus suited for single-particle TIRF microscopy of dense biological samples in which the intensity itself is an observable of the technique.
    Keywords: Biology
    ISSN: 0006-3495
    E-ISSN: 1542-0086
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  • 5
    Language: English
    In: PLoS ONE, 2011, Vol.6(3), p.e17744
    Description: The naked mole-rat ( Heterocephalus glaber ) is one of the two known mammalian species that live in a eusocial population structure. Here we investigate the exceptionally long gestation period of 70 days observed in the mole-rat queen. The course of seven successful pregnancies in two individuals was recorded in a colony of captive naked mole-rats using ultrasound biomicroscopy (UBM) and 3D-ultrasonography. We establish a catalogue of basic reference ultrasound data for this species by describing the ultrasonographic appearance of reproductive organs, calculating growth curves to predict gestational age and defining ultrasonographic milestones to characterize pregnancy stages. Mean litter size was 10.9±2.7, of which 7.2±1.5 survived the weaning period. Mean interbirth interval was 128.8±63.0 days. The reproductive success in our colony did not differ from previously published data. In the queen the active corpora lutea had an anechoic, fluid filled centre. Using UBM, pregnancy could be detected 53 days before parturition. The period of embryonic development is assumed to last until 30 days before parturition. Embryonic resorptions were detected frequently in the queen, indicating that this might be an ordinary event in this species. We discuss the extraordinary long gestation period of this small rodent and postulate that the long gestation is beneficial to both the eusocial structure and longevity. An increased litter size, twice as large as for other rodents of similar size, seemingly compensates for the doubling of pregnancy length. We demonstrate that the lifetime reproductive effort of a naked mole-rat queen is equivalent to the mass of offspring that would be produced if all of the females of a colony would be reproducing.
    Keywords: Research Article ; Biology ; Veterinary Science ; Physiology ; Developmental Biology ; Evolutionary Biology
    E-ISSN: 1932-6203
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  • 6
    Language: English
    In: PLoS ONE, 2011, Vol.6(9), p.e23796
    Description: Factors and mechanisms controlling lipometabolism homeostasis share a remarkable evolutionary conservation between humans and Drosophila flies. Accordingly, the Drosophila model has been successfully used to understand the pathophysiology of human metabolic diseases such as obesity. Body fat stores in species as different as humans and flies consist of neutral lipids, mainly triacylglycerols. Changes in body fat storage are a diagnostic phenotype of lipometabolism imbalances of genetic or environmental origin. Various methods have been developed to quantify Drosophila body fat storage. The most widely used method adopts a commercial coupled colorimetric assay designed for human serum triacylglycerol quantification, which is based on glycerol content determination after enzymatic conversion of glycerides into glycerol. The coupled colorimetric assay is compatible with large-scale genetic screen approaches and has been successfully applied to characterize central regulators of Drosophila lipometabolism. Recently, the applicability of the coupled colorimetric assay for Drosophila storage fat quantification has been questioned in principle. Here we compare the performance of the coupled colorimetric assay on Drosophila samples with thin layer chromatography, the “gold standard” in storage lipid analysis. Our data show that the presented variant of the coupled colorimetric assay reliably discriminates between lean and fat flies and allows robust, quick and cost-effective quantification of Drosophila body fat stores.
    Keywords: Research Article ; Biology ; Genetics And Genomics ; Biochemistry
    E-ISSN: 1932-6203
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  • 7
    Language: English
    In: PLoS ONE, 2011, Vol.6(8), p.e23686
    Description: Ablation of a cochlea causes total sensory deafferentation of the cochlear nucleus in the brainstem, providing a model to investigate nervous degeneration and formation of new synaptic contacts in the adult brain. In a quantitative electron microscopical study on the plasticity of the central auditory system of the Wistar rat, we first determined what fraction of the total number of synaptic contact zones (SCZs) in the anteroventral cochlear nucleus (AVCN) is attributable to primary sensory innervation and how many synapses remain after total unilateral cochlear ablation. Second, we attempted to identify the potential for a deafferentation-dependent synaptogenesis. SCZs were ultrastructurally identified before and after deafferentation in tissue treated for ethanolic phosphotungstic acid (EPTA) staining. This was combined with pre-embedding immunocytochemistry for gephyrin identifying inhibitory SCZs, the growth-associated protein GAP-43, glutamate, and choline acetyltransferase. A stereological analysis of EPTA stained sections revealed 1.11±0.09 (S.E.M.)×10 9 SCZs per mm 3 of AVCN tissue. Within 7 days of deafferentation, this number was down by 46%. Excitatory and inhibitory synapses were differentially affected on the side of deafferentation. Excitatory synapses were quickly reduced and then began to increase in number again, necessarily being complemented from sources other than cochlear neurons, while inhibitory synapses were reduced more slowly and continuously. The result was a transient rise of the relative fraction of inhibitory synapses with a decline below original levels thereafter. Synaptogenesis was inferred by the emergence of morphologically immature SCZs that were consistently associated with GAP-43 immunoreactivity. SCZs of this type were estimated to make up a fraction of close to 30% of the total synaptic population present by ten weeks after sensory deafferentation. In conclusion, there appears to be a substantial potential for network reorganization and synaptogenesis in the auditory brainstem after loss of hearing, even in the adult brain.
    Keywords: Research Article ; Biology ; Neuroscience
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: The Journal of experimental biology, 15 April 2016, Vol.219(Pt 8), pp.1139-45
    Description: Sanguivorous leeches are ectoparasites having access to body fluids of potential hosts only infrequently. During feeding, salivary proteins are released from unicellular salivary glands into the wound. These substances, among them anti-coagulants, anti-inflammatory or anti-microbial agents, allow these animals proper feeding and long-term storage of host blood in their crops for several months. Using histological, protein biochemical and molecular techniques, we investigated whether synthesis of salivary proteins and refilling of salivary gland cells occur immediately after feeding or later when stored nutrients in the crop are getting scarce. The results of the histological analyses showed that gland cell area was significantly smaller right after feeding when compared with those in unfed animals. This parameter recovered quickly and reached the control level at 1 week after feeding. 2D gel electrophoresis and analysis of the abundance of individual proteins in extracts of leech tissues revealed that a subset of proteins that had been present in extracts of unfed animals virtually disappeared during feeding, but re-appeared within 1 week of feeding (most probably secretory proteins) while another subset did not change during the experimental period (most probably housekeeping proteins). Semi-quantitative PCR analysis of hirudin cDNA prepared from leech RNA samples revealed that the amount of hirudin transcripts increased immediately after feeding, peaked at 5 days after feeding and declined to control values thereafter. Our results indicate that bloodsucking leeches synthesize salivary proteins and refill their salivary gland cell reservoirs within a week of a blood meal to be prepared for another feeding opportunity.
    Keywords: Blood Feeding ; Hirudin ; Salivary Protein Cocktail ; Salivary Protein Synthesis ; Sanguivorous Leech ; Feeding Behavior ; Leeches -- Metabolism ; Postprandial Period -- Physiology ; Salivary Glands -- Cytology ; Salivary Proteins and Peptides -- Biosynthesis
    ISSN: 00220949
    E-ISSN: 1477-9145
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  • 9
    Language: English
    In: Biophysical Journal, 27 January 2015, Vol.108(2), pp.163a-163a
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.bpj.2014.11.898 Byline: Soren Preus, Lasse Hildebrandt, Sofie L. Noer, Victoria Birkedal Author Affiliation: Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark Article Note: (miscellaneous) 815-PosB595
    Keywords: Biology
    ISSN: 0006-3495
    E-ISSN: 1542-0086
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  • 10
    Language: English
    In: Science, 8 January 2010, Vol.327(5962), pp.198-201
    Description: The liver-expressed microRNA-122 (miR-122) is essential for hepatitis C virus (HCV) RNA accumulation in cultured liver cells, but its potential as a target for antiviral intervention has not been assessed. We found that treatment of chronically infected chimpanzees with a locked nucleic acid (LNA)-modified oligonucleotide (SPC3649) complementary to miR-122 leads to long-lasting suppression of HCV viremia, with no evidence of viral resistance or side effects in the treated animals. Furthermore, transcriptome and histological analyses of liver biopsies demonstrated derepression of target mRNAs with miR-122 seed sites, down-regulation of interferon-regulated genes, and improvement of HCV-induced liver pathology. The prolonged virological response to SPC3649 treatment without HCV rebound holds promise of a new antiviral therapy with a high barrier to resistance.
    Keywords: Biological sciences -- Biology -- Anatomy ; Physical sciences -- Chemistry -- Chemical compounds ; Health sciences -- Medical conditions -- Infections ; Health sciences -- Medical diagnosis -- Diagnostic methods ; Health sciences -- Medical conditions -- Infections ; Physical sciences -- Chemistry -- Chemical compounds ; Biological sciences -- Biology -- Zoology ; Biological sciences -- Biology -- Physiology ; Physical sciences -- Earth sciences -- Geography ; Biological sciences -- Biology -- Microbiology ; Biological sciences -- Biology -- Anatomy ; Physical sciences -- Chemistry -- Chemical compounds ; Health sciences -- Medical conditions -- Infections ; Health sciences -- Medical diagnosis -- Diagnostic methods ; Health sciences -- Medical conditions -- Infections ; Physical sciences -- Chemistry -- Chemical compounds ; Biological sciences -- Biology -- Zoology ; Biological sciences -- Biology -- Physiology ; Physical sciences -- Earth sciences -- Geography ; Biological sciences -- Biology -- Microbiology
    ISSN: 00368075
    E-ISSN: 10959203
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