1-20 von 264 Publikationen

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      Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia 

      Sabajo, Clifton R.; le Maire, Guerric; June, Tania; Meijide, Ana; Roupsard, Olivier; Knohl, Alexander
      Biogeosciences 2017; 14(20) p.4619-4635
      Indonesia is currently one of the regions with the highest transformation rate of land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. Land cover changes, which modify land surface properties, have a direct effect on the land surface temperature (LST), a key driver for many ecological functions. Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on the LST in Indonesia. We analyze LST from the thermal band of a Landsat image and produce a highresolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which suffered large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, normalized differenced vegetation index (NDVI) and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear-cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 2.6 C (mean SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets the albedo warming effect. Our analysis of the LST trend of the past 16 years based on MODIS data shows that the average daytime surface temperature in the Jambi province increased by 1.05 C, which followed the trend of observed land cover changes and exceeded the effects of climate warming. This study provides evidence that the expansion of oil palm plantations and other cash crops leads to changes in biophysical variables, warming the land surface and thus enhancing the increase of the air temperature because of climate change.
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      Bayesian refinement of protein structures and ensembles against SAXS data using molecular dynamics. 

      Shevchuk, Roman; Hub, Jochen S.
      PLoS computational biology 2017-10; 13(10): Art. e1005800
      Small-angle X-ray scattering is an increasingly popular technique used to detect protein structures and ensembles in solution. However, the refinement of structures and ensembles against SAXS data is often ambiguous due to the low information content of SAXS data, unknown systematic errors, and unknown scattering contributions from the solvent. We offer a solution to such problems by combining Bayesian inference with all-atom molecular dynamics simulations and explicit-solvent SAXS calculations. The Bayesian formulation correctly weights the SAXS data versus prior physical knowledge, it quantifies the precision or ambiguity of fitted structures and ensembles, and it accounts for unknown systematic errors due to poor buffer matching. The method further provides a probabilistic criterion for identifying the number of states required to explain the SAXS data. The method is validated by refining ensembles of a periplasmic binding protein against calculated SAXS curves. Subsequently, we derive the solution ensembles of the eukaryotic chaperone heat shock protein 90 (Hsp90) against experimental SAXS data. We find that the SAXS data of the apo state of Hsp90 is compatible with a single wide-open conformation, whereas the SAXS data of Hsp90 bound to ATP or to an ATP-analogue strongly suggest heterogenous ensembles of a closed and a wide-open state.
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      INA complex liaises the F1Fo-ATP synthase membrane motor modules. 

      Naumenko, Nataliia; Morgenstern, Marcel; Rucktäschel, Robert; Warscheid, Bettina; Rehling, Peter
      Nature communications 2017-11-01; 8(1): Art. 1237
      The F1F0-ATP synthase translates a proton flux across the inner mitochondrial membrane into a mechanical rotation, driving anhydride bond formation in the catalytic portion. The complex's membrane-embedded motor forms a proteinaceous channel at the interface between Atp9 ring and Atp6. To prevent unrestricted proton flow dissipating the H(+)-gradient, channel formation is a critical and tightly controlled step during ATP synthase assembly. Here we show that the INA complex (INAC) acts at this decisive step promoting Atp9-ring association with Atp6. INAC binds to newly synthesized mitochondrial-encoded Atp6 and Atp8 in complex with maturation factors. INAC association is retained until the F1-portion is built on Atp6/8 and loss of INAC causes accumulation of the free F1. An independent complex is formed between INAC and the Atp9 ring. We conclude that INAC maintains assembly intermediates of the F1 F0-ATP synthase in a primed state for the terminal assembly step-motor module formation.
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    • Working Paper

      “Go hard or go home!” 

      Kiep, Peter
      Göttinger Centrum für Geschlechterforschung, 2017
      Der gegenwärtige Trend der Körpermodellierung hat in den letzten Jahren ebenso stetig Veränderungen erfahren wie das kommerzielle Fitnessstudio als ein anerkannter Ort der Artikulation moderner Körperlichkeit. Dies zeigt sich insbesondere an den gestiegenen Ansprüchen hinsichtlich gesellschaftlich akzeptierter Körperideale. Dabei bedingt das Sporttreiben im Fitnessstudio positive wie auch negative Erfahrungen, die an das Aussehen und die sportliche Leistung gebunden sind. Hiervon ausgehend nimmt die vorliegende Studie an der Schnittstelle von Sportwissenschaften und Geschlechterforschung die Frage in den Blick, welche Bedeutung diverse Körper(-formen) für die Anerkennung junger Männer innerhalb der Fitnessszene haben. Hierbei werden zum einen positive Anerkennungserfahrungen basierend auf der richtigen Selbstinszenierung sowie der sportlichen Leistung deutlich. Zum anderen werden Abhängigkeiten zwischen Hierarchien unter Männern, körperbezogenen Diskriminierungstendenzen und der selbstbestimmten Teilnahme am körpermodellierenden Sport sichtbar.
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    • Zeitschriftenartikel

      Compromised neuroplasticity in cigarette smokers under nicotine withdrawal is restituted by the nicotinic α4β2-receptor partial agonist varenicline 

      Batsikadze, G.; Paulus, W.; Hasan, A.; Grundey, J.; Kuo, M.-F.; Nitsche, M. A.
      Scientific Reports 2017; 7(1): Art. 1387
      Nicotine modulates neuroplasticity and improves cognitive functions in animals and humans. In the brain of smoking individuals, calcium-dependent plasticity induced by non-invasive brain stimulation methods such as transcranial direct current stimulation (tDCS) and paired associative stimulation (PAS) is impaired by nicotine withdrawal, but partially re-established after nicotine re-administration. In order to investigate the underlying mechanism further, we tested the impact of the α4β2-nicotinic receptor partial agonist varenicline on focal and non-focal plasticity in smokers during nicotine withdrawal, induced by PAS and tDCS, respectively. We administered low (0.3 mg) and high (1.0 mg) single doses of varenicline or placebo medication before stimulation over the left motor cortex of 20 healthy smokers under nicotine withdrawal. Motor cortex excitability was monitored by single-pulse transcranial magnetic stimulation-induced motor evoked potential amplitudes for 36 hours after plasticity induction. Stimulation-induced plasticity was absent under placebo medication, whereas it was present in all conditions under high dose. Low dose restituted only tDCS-induced non-focal plasticity, producing no significant impact on focal plasticity. High dose varenicline also prolonged inhibitory plasticity. These results are comparable to the impact of nicotine on withdrawal-related impaired plasticity in smokers and suggest that α4β2 nicotinic receptors are relevantly involved in plasticity deficits and restitution in smokers.
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      Regulation of Prp43-mediated disassembly of spliceosomes by its cofactors Ntr1 and Ntr2 

      Fourmann, Jean-Baptiste; Tauchert, Marcel J.; Ficner, Ralf; Fabrizio, Patrizia; Lührmann, Reinhard
      Nucleic Acids Research 2016; 45(7) p.4068-4080
      The DEAH-box NTPase Prp43 disassembles spliceosomes in co-operation with the cofactors Ntr1/Spp382 and Ntr2, forming the NTR complex. How Prp43 is regulated by its cofactors to discard selectively only intron-lariat spliceosomes (ILS) and defective spliceosomes and to prevent disassembly of earlier and properly assembled/wild-type spliceosomes remains unclear. First, we show that Ntr1΄s G-patch motif (Ntr1GP) can be replaced by the GP motif of Pfa1/Sqs1, a Prp43΄s cofactor in ribosome biogenesis, demonstrating that the specific function of Ntr1GP is to activate Prp43 for spliceosome disassembly and not to guide Prp43 to its binding site in the spliceosome. Furthermore, we show that Ntr1΄s C-terminal domain (CTD) plays a safeguarding role by preventing Prp43 from disrupting wild-type spliceosomes other than the ILS. Ntr1 and Ntr2 can also discriminate between wild-type and defective spliceosomes. In both type of spliceosomes, Ntr1-CTD impedes Prp43-mediated disassembly while the Ntr1GP promotes disassembly. Intriguingly, Ntr2 plays a specific role in defective spliceosomes, likely by stabilizing Ntr1 and allowing Prp43 to enter a productive interaction with the GP motif of Ntr1. Our data indicate that Ntr1 and Ntr2 act as ‘doorkeepers’ and suggest that both cofactors inspect the RNP structure of spliceosomal complexes thereby targeting suboptimal spliceosomes for Prp43-mediated disassembly.
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      BRD4 promotes p63 and GRHL3 expression downstream of FOXO in mammary epithelial cells 

      Nagarajan, Sankari; Bedi, Upasana; Budida, Anusha; Hamdan, Feda H.; Mishra, Vivek Kumar; Najafova, Zeynab; Xie, Wanhua; Alawi, Malik; Indenbirken, Daniela; Knapp, Stefan; et al.
      Chiang, Cheng-MingGrundhoff, AdamKari, VijayalakshmiScheel, Christina H.Wegwitz, FlorianJohnsen, Steven A.
      Nucleic Acids Research 2016; 45(6) p.3130-3145
      Bromodomain-containing protein 4 (BRD4) is a member of the bromo- and extraterminal (BET) domain-containing family of epigenetic readers which is under intensive investigation as a target for anti-tumor therapy. BRD4 plays a central role in promoting the expression of select subsets of genes including many driven by oncogenic transcription factors and signaling pathways. However, the role of BRD4 and the effects of BET inhibitors in non-transformed cells remain mostly unclear. We demonstrate that BRD4 is required for the maintenance of a basal epithelial phenotype by regulating the expression of epithelial-specific genes including TP63 and Grainy Head-like transcription factor-3 (GRHL3) in non-transformed basal-like mammary epithelial cells. Moreover, BRD4 occupancy correlates with enhancer activity and enhancer RNA (eRNA) transcription. Motif analyses of cell context-specific BRD4-enriched regions predicted the involvement of FOXO transcription factors. Consistently, activation of FOXO1 function via inhibition of EGFR-AKT signaling promoted the expression of TP63 and GRHL3. Moreover, activation of Src kinase signaling and FOXO1 inhibition decreased the expression of FOXO/BRD4 target genes. Together, our findings support a function for BRD4 in promoting basal mammary cell epithelial differentiation, at least in part, by regulating FOXO factor function on enhancers to activate TP63 and GRHL3 expression.
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      The house spider genome reveals an ancient whole-genome duplication during arachnid evolution 

      Schwager, Evelyn E.; Sharma, Prashant P.; Clarke, Thomas; Leite, Daniel J.; Wierschin, Torsten; Pechmann, Matthias; Akiyama-Oda, Yasuko; Esposito, Lauren; Bechsgaard, Jesper; Bilde, Trine; et al.
      Buffry, Alexandra D.Chao, HsuDinh, HuyenDoddapaneni, HarshaVardhanDugan, ShannonEibner, CorneliusExtavour, Cassandra G.Funch, PeterGarb, JessicaGonzalez, Luis B.Gonzalez, Vanessa L.Griffiths-Jones, SamHan, YiHayashi, CherylHilbrant, MaartenHughes, Daniel S. T.Janssen, RalfLee, Sandra L.Maeso, IgnacioMurali, Shwetha C.Muzny, Donna M.Nunes da Fonseca, RodrigoPaese, Christian L. B.Qu, JiaxinRonshaugen, MatthewSchomburg, ChristophSchönauer, AnnaStollewerk, AngelikaTorres-Oliva, MontserratTuretzek, NataschaVanthournout, BramWerren, John H.Wolff, CarstenWorley, Kim C.Bucher, GregorGibbs, Richard A.Coddington, JonathanOda, HirokiStanke, MarioAyoub, Nadia A.Prpic, Nikola-MichaelFlot, Jean-FrançoisPosnien, NicoRichards, StephenMcGregor, Alistair P.
      BMC Biology 2017; 15(62) p.1-27
      The duplication of genes can occur through various mechanisms and is thought to make a major contribution to the evolutionary diversification of organisms. There is increasing evidence for a large-scale duplication of genes in some chelicerate lineages including two rounds of whole genome duplication (WGD) in horseshoe crabs. To investigate this further, we sequenced and analyzed the genome of the common house spider Parasteatoda tepidariorum. We found pervasive duplication of both coding and non-coding genes in this spider, including two clusters of Hox genes. Analysis of synteny conservation across the P. tepidariorum genome suggests that there has been an ancient WGD in spiders. Comparison with the genomes of other chelicerates, including that of the newly sequenced bark scorpion Centruroides sculpturatus, suggests that this event occurred in the common ancestor of spiders and scorpions, and is probably independent of the WGDs in horseshoe crabs. Furthermore, characterization of the sequence and expression of the Hox paralogs in P. tepidariorum suggests that many have been subject to neo-functionalization and/or sub-functionalization since their duplication. Our results reveal that spiders and scorpions are likely the descendants of a polyploid ancestor that lived more than 450 MYA. Given the extensive morphological diversity and ecological adaptations found among these animals, rivaling those of vertebrates, our study of the ancient WGD event in Arachnopulmonata provides a new comparative platform to explore common and divergent evolutionary outcomes of polyploidization events across eukaryotes.
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      Rapid diversification of homothorax expression patterns after gene duplication in spiders 

      Turetzek, Natascha; Khadjeh, Sara; Schomburg, Christoph; Prpic, Nikola-Michael
      BMC Evolutionary Biology 2017; 17(1)
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    • Working Paper

      Zur symbolischen Kastration von traditionellen Männlichkeiten 

      Schwanke, Julia
      Göttinger Centrum für Geschlechterforschung: Göttingen, 2017
      Die österreichische Schriftstellerin Elfriede Jelinek (*1946) gilt als Autorin, die durch die überspitzte Darstellung der männlichen Herrschaft patriarchale Herrschaftsformen kritisiert. Der vorliegende Beitrag analysiert zwei Romane Jelineks der 1980er Jahre aus gendertheoretischer Sicht: Die Ausgesperr-ten und Die Klavierspielerin. Es wird gezeigt, dass Jelinek über eine einfache Patriarchatskritik hinaus-geht, indem sie die männliche Herrschaft ad absurdum führt – sie führt symbolisch kastrierte Männ-lichkeiten als Persiflage einer traditionellen Männlichkeit vor. Für die Analyse werden soziologische geschlechts- und klassentheoretische Ansätze mit einer Methode zur Figurenanalyse verbunden. Mi-chael Meusers Ansatz, welcher Raewyn Connells Konzept der hegemonialen Männlichkeit mit Pierre Bourdieus Habitus-Konzept verbindet, wird in die Figurenanalyse Jens Eders integriert. Dadurch wird die Performanz von Männlichkeit in Jelineks Prosa sichtbar(er) gemacht und in den Kontext ei-ner doppelten Distinktions- und Dominanzlogik eingeordnet. Im Zuge der Analyse wird deutlich, dass die männlichen Figuren, welche sich bei der Konstruktion ihrer Männlichkeit am Ideal der he-gemonialen Männlichkeit orientieren, zum Scheitern verurteilt sind. Sie können den Anforderungen, die das Patriarchat mit der Verkörperung einer hegemonialen Männlichkeit an sie stellt, nicht gerecht werden. Jelinek kastriert sie symbolisch.
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    • Zeitschriftenartikel

      Levels and trends of childhood undernutrition by wealth and education according to a Composite Index of Anthropometric Failure: evidence from 146 Demographic and Health Surveys from 39 countries 

      Vollmer, Sebastian; Harttgen, Kenneth; Kupka, Roland; Subramanian, S. V.
      BMJ Global Health 2017; 2(2): Art. e000206
      Background Governments have endorsed global targets to reduce childhood undernutrition as part of the Sustainable Development Goals. Understanding the socioeconomic differences in childhood undernutrition has the potential to be helpful for targeting policy to reach these goals. Methods We specify a logistic regression model with the Composite Index of Anthropometric Failure (CIAF) as the outcome and indicator variables for wealth quartiles, maternal education categories and a set of covariates as explanatory variables. Wealth and education variables are interacted with a period indicator for 1990–2000 compared with 2001–2014 to observe differences over time. Based on these regressions we calculate predicted CIAF prevalence by wealth and education categories and over time. Results The sample included 146 surveys from 39 low-income and lower-middle-income countries with an overall sample size of 533 217 children. CIAF prevalence was 47.5% in 1990–2000, and it declined to 42.6% in 2001–2014. In 1990–2000 the CIAF prevalence of children with mothers with less than primary education was 31 percentage points higher than for mothers with secondary or higher education. This difference slightly decreased to 27 percentage points in 2001–2014. The difference in predicted CIAF prevalence of children from the highest and lowest wealth quartiles was 21 percentage points and did not change over time. Conclusions We find evidence for persistent and even increasing socioeconomic inequalities in childhood undernutrition, which underlines the importance of previous calls for equity-driven approaches targeting the most vulnerable to reduce childhood malnutrition.
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      Breakdown of local information processing may underlie isoflurane anesthesia effects. 

      Wollstadt, Patricia; Sellers, Kristin K; Rudelt, Lucas; Priesemann, Viola; Hutt, Axel; Fröhlich, Flavio; Wibral, Michael
      PLoS computational biology 2017-06; 13(6): Art. e1005511
      The disruption of coupling between brain areas has been suggested as the mechanism underlying loss of consciousness in anesthesia. This hypothesis has been tested previously by measuring the information transfer between brain areas, and by taking reduced information transfer as a proxy for decoupling. Yet, information transfer is a function of the amount of information available in the information source-such that transfer decreases even for unchanged coupling when less source information is available. Therefore, we reconsidered past interpretations of reduced information transfer as a sign of decoupling, and asked whether impaired local information processing leads to a loss of information transfer. An important prediction of this alternative hypothesis is that changes in locally available information (signal entropy) should be at least as pronounced as changes in information transfer. We tested this prediction by recording local field potentials in two ferrets after administration of isoflurane in concentrations of 0.0%, 0.5%, and 1.0%. We found strong decreases in the source entropy under isoflurane in area V1 and the prefrontal cortex (PFC)-as predicted by our alternative hypothesis. The decrease in source entropy was stronger in PFC compared to V1. Information transfer between V1 and PFC was reduced bidirectionally, but with a stronger decrease from PFC to V1. This links the stronger decrease in information transfer to the stronger decrease in source entropy-suggesting reduced source entropy reduces information transfer. This conclusion fits the observation that the synaptic targets of isoflurane are located in local cortical circuits rather than on the synapses formed by interareal axonal projections. Thus, changes in information transfer under isoflurane seem to be a consequence of changes in local processing more than of decoupling between brain areas. We suggest that source entropy changes must be considered whenever interpreting changes in information transfer as decoupling.
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      What makes a reach movement effortful? Physical effort discounting supports common minimization principles in decision making and motor control. 

      Morel, Pierre; Ulbrich, Philipp; Gail, Alexander
      PLoS biology 2017-06; 15(6): Art. e2001323
      When deciding between alternative options, a rational agent chooses on the basis of the desirability of each outcome, including associated costs. As different options typically result in different actions, the effort associated with each action is an essential cost parameter. How do humans discount physical effort when deciding between movements? We used an action-selection task to characterize how subjective effort depends on the parameters of arm transport movements and controlled for potential confounding factors such as delay discounting and performance. First, by repeatedly asking subjects to choose between 2 arm movements of different amplitudes or durations, performed against different levels of force, we identified parameter combinations that subjects experienced as identical in effort (isoeffort curves). Movements with a long duration were judged more effortful than short-duration movements against the same force, while movement amplitudes did not influence effort. Biomechanics of the movements also affected effort, as movements towards the body midline were preferred to movements away from it. Second, by introducing movement repetitions, we further determined that the cost function for choosing between effortful movements had a quadratic relationship with force, while choices were made on the basis of the logarithm of these costs. Our results show that effort-based action selection during reaching cannot easily be explained by metabolic costs. Instead, force-loaded reaches, a widely occurring natural behavior, imposed an effort cost for decision making similar to cost functions in motor control. Our results thereby support the idea that motor control and economic choice are governed by partly overlapping optimization principles.
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      Working Memory Requires a Combination of Transient and Attractor-Dominated Dynamics to Process Unreliably Timed Inputs. 

      Nachstedt, Timo; Tetzlaff, Christian
      Scientific reports 2017-05-30; 7(1): Art. 2473
      Working memory stores and processes information received as a stream of continuously incoming stimuli. This requires accurate sequencing and it remains puzzling how this can be reliably achieved by the neuronal system as our perceptual inputs show a high degree of temporal variability. One hypothesis is that accurate timing is achieved by purely transient neuronal dynamics; by contrast a second hypothesis states that the underlying network dynamics are dominated by attractor states. In this study, we resolve this contradiction by theoretically investigating the performance of the system using stimuli with differently accurate timing. Interestingly, only the combination of attractor and transient dynamics enables the network to perform with a low error rate. Further analysis reveals that the transient dynamics of the system are used to process information, while the attractor states store it. The interaction between both types of dynamics yields experimentally testable predictions and we show that this way the system can reliably interact with a timing-unreliable Hebbian-network representing long-term memory. Thus, this study provides a potential solution to the long-standing problem of the basic neuronal dynamics underlying working memory.
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      Panya: Economies of Deception and the Discontinuities of Indentured Labour Recruitment and the Slave Trade, Nigeria and Fernando Pó, 1890s–1940s 

      Martino, Enrique
      African Economic History 2016; 44(1) p.91-129
      In the first half of the twentieth century, most of Fernando Pó’s contract workers came from societies in southeastern Nigeria which had been heavily impacted by the transatlantic and internal slave trades. These contract workers were recruited by a new generation of labor recruiters, dispatched covertly by Spanish imperial employers, through a form of kidnapping known as panya. Panya was the largest labor smuggling and trafficking network in colonial West Africa, bringing tens of thousands of migrants to long and obligatory contracts on Fernando Pó. In contrast to scholars who have interpreted this history as a holdover from the pre-colonial period, this article argues that panya arose from the contractual order of Spanish imperial rule. Extensive archival research reveals the voices of those caught in the warp of post-abolition colonial labor regimes, in order to rethink the passage from the pre-colonial slave trade to imperialism within West African history. Using a series of vivid and precise petitions submitted by those who found themselves on the island of Fernando Pó, the article shows how these sources contain the potential to reconceptualize the disjunctures between enslavement in the slave trade and the recruitment of contract labor.
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      Dash-peonage: the contradictions of debt bondage in the colonial plantations of Fernando Pó 

      Martino, Enrique
      Africa 2017; 87(1) p.53-78
      Dash in pidgin English means an ancillary gift to an exchange. What happened when the dash became attached to the indentured labour contracts that the Spanish Empire brought from Cuba to their last colony, Spanish Guinea? On the island of Fernando Pó, which came to be almost wholly populated by Nigerian labour migrants, the conditional gift in the form of a large wage advance produced a particularly intense contradiction. In the historiography of unfree labour, the excess wage advance is thought to create conditions for the perpetuation of bondage through debt. However, in imperial contexts, the wage advance did not generate compliance and immobility; exactly the opposite – it produced unprecedented waves of further escalation and dispersed flight. The dash was pushed up by workers themselves and relayed by informal recruiters. Together they turned this lynchpin of indentured labour and debt peonage into a counter-practice that almost led to the collapse of the plantations in the 1950s. The trajectories of the dash led to a more pointed version of the foundational thesis of global labour history: namely, that it was actually free labour, not unfree labour, that was incompatible with labour scarcity-ridden imperial capitalism.
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      Analysis of the lipid body proteome of the oleaginous alga Lobosphaera incisa 

      Siegler, Heike; Valerius, Oliver; Ischebeck, Till; Popko, Jennifer; Tourasse, Nicolas J; Vallon, Olivier; Khozin-Goldberg, Inna; Braus, Gerhard H; Feussner, Ivo
      BMC Plant Biology 2017; 17(1): Art. 98
      Abstract Background Lobosphaera incisa (L. incisa) is an oleaginous microalga that stores triacylglycerol (TAG) rich in arachidonic acid in lipid bodies (LBs). This organelle is gaining attention in algal research, since evidence is accumulating that proteins attached to its surface fulfill important functions in TAG storage and metabolism. Results Here, the composition of the LB proteome in L incisa was investigated by comparing different cell fractions in a semiquantitative proteomics approach. After applying stringent filters to the proteomics data in order to remove contaminating proteins from the list of possible LB proteins (LBPs), heterologous expression of candidate proteins in tobacco pollen tubes, allowed us to confirm 3 true LBPs: A member of the algal Major Lipid Droplet Protein family, a small protein of unknown function and a putative lipase. In addition, a TAG lipase that belongs to the SUGAR DEPENDENT 1 family of TAG lipases known from oilseed plants was identified. Its activity was verified by functional complementation of an Arabidopsis thaliana mutant lacking the major seed TAG lipases. Conclusions Here we describe 3 LBPs as well as a TAG lipase from the oleaginous microalga L. incisa and discuss their possible involvement in LB metabolism. This study highlights the importance of filtering LB proteome datasets and verifying the subcellular localization one by one, so that contaminating proteins can be recognized as such. Our dataset can serve as a valuable resource in the identification of additional LBPs, shedding more light on the intriguing roles of LBs in microalgae.
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      Subsampling scaling 

      Levina, A.; Priesemann, V.
      Nature Communications 2017; 8: Art. 15140
      In real-world applications, observations are often constrained to a small fraction of a system. Such spatial subsampling can be caused by the inaccessibility or the sheer size of the system, and cannot be overcome by longer sampling. Spatial subsampling can strongly bias inferences about a system’s aggregated properties. To overcome the bias, we derive analytically a subsampling scaling framework that is applicable to different observables, including distributions of neuronal avalanches, of number of people infected during an epidemic outbreak, and of node degrees. We demonstrate how to infer the correct distributions of the underlying full system, how to apply it to distinguish critical from subcritical systems, and how to disentangle subsampling and finite size effects. Lastly, we apply subsampling scaling to neuronal avalanche models and to recordings from developing neural networks. We show that only mature, but not young networks follow power-law scaling, indicating self-organization to criticality during development.
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      The effect of hypoxia on the lipidome of recombinant Pichia pastoris 

      Adelantado, Núria; Tarazona, Pablo; Grillitsch, Karlheinz; García-Ortega, Xavier; Monforte, Sergi; Valero, Francisco; Feussner, Ivo; Daum, Günther; Ferrer, Pau
      Microbial Cell Factories 2017; 16(1): Art. 86
      Abstract Background Cultivation of recombinant Pichia pastoris (Komagataella sp.) under hypoxic conditions has a strong positive effect on specific productivity when the glycolytic GAP promoter is used for recombinant protein expression, mainly due to upregulation of glycolytic conditions. In addition, transcriptomic analyses of hypoxic P. pastoris pointed out important regulation of lipid metabolism and unfolded protein response (UPR). Notably, UPR that plays a role in the regulation of lipid metabolism, amino acid metabolism and protein secretion, was found to be upregulated under hypoxia. Results To improve our understanding of the interplay between lipid metabolism, UPR and protein secretion, the lipidome of a P. pastoris strain producing an antibody fragment was studied under hypoxic conditions. Furthermore, lipid composition analyses were combined with previously available transcriptomic datasets to further understand the impact of hypoxia on lipid metabolism. Chemostat cultures operated under glucose-limiting conditions under normoxic and hypoxic conditions were analyzed in terms of intra/extracellular product distribution and lipid composition. Integrated analysis of lipidome and transcriptome datasets allowed us to demonstrate an important remodeling of the lipid metabolism under limited oxygen availability. Additionally, cells with reduced amounts of ergosterol through fluconazole treatment were also included in the study to observe the impact on protein secretion and its lipid composition. Conclusions Our results show that cells adjust their membrane composition in response to oxygen limitation mainly by changing their sterol and sphingolipid composition. Although fluconazole treatment results a different lipidome profile than hypoxia, both conditions result in higher recombinant protein secretion levels.
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    • Working Paper

      (Wie) Die O-Phase verändern? 

      Volpers, Simon; Brodersen, Folke
      Göttinger Centrum für Geschlechterforschung: Göttingen, 2017
      Basierend auf qualitativen Erhebungen (teilnehmende Beobachtung, themenzentriert-narratives Inter-view) in den‚ Orientierungsphasen der Studienfächer Physik, Wirtschaftswissenschaften und Sozialwissenschaften werden Göttinger Praxen studentischer Hochschuleinführung rekonstruiert. Diese erfahren in öffentlich-medialen wie hochschulinternen Diskursen eine zunehmende Kritik. Der Beitrag folgt den sich andeutenden Diskursbewegungen, die auf Basis der strukturellen Eigenlogiken der sog. O-Phase verortet und kontrastiert werden. Erörtert werden eine Grundstruktur des Exzesses, darin eingebettete, gewaltförmige vergeschlechtlichte und sexualisierte Praxen sowie die Funktionalität und Anschlussfähigkeit dieser Form des Studieneinstiegs innerhalb gegenwärtiger Transformationen der Hochschule. Der Beitrag entwickelt eine empirisch fundierte Perspektivierung, Zusammenführung und Reformulierung von Kritik.
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