36 research outputs found

    The kinesin Eg5 drives poleward microtubule flux in Xenopus laevis egg extract spindles

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    Although mitotic and meiotic spindles maintain a steady-state length during metaphase, their antiparallel microtubules slide toward spindle poles at a constant rate. This “poleward flux” of microtubules occurs in many organisms and may provide part of the force for chromosome segregation. We use quantitative image analysis to examine the role of the kinesin Eg5 in poleward flux in metaphase Xenopus laevis egg extract spindles. Pharmacological inhibition of Eg5 results in a dose–responsive slowing of flux, and biochemical depletion of Eg5 significantly decreases the flux rate. Our results suggest that ensembles of nonprocessive Eg5 motors drive flux in metaphase Xenopus extract spindles

    Peasant settlers and the ‘civilizing mission’ in Russian Turkestan, 1865-1917

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    This article provides an introduction to one of the lesser-known examples of European settler colonialism, the settlement of European (mainly Russian and Ukrainian) peasants in Southern Central Asia (Turkestan) in the late nineteenth and early twentieth centuries. It establishes the legal background and demographic impact of peasant settlement, and the role played by the state in organising and encouraging it. It explores official attitudes towards the settlers (which were often very negative), and their relations with the local Kazakh and Kyrgyz population. The article adopts a comparative framework, looking at Turkestan alongside Algeria and Southern Africa, and seeking to establish whether paradigms developed in the study of other settler societies (such as the ‘poor white’) are of any relevance in understanding Slavic peasant settlement in Turkestan. It concludes that there are many close parallels with European settlement in other regions with large indigenous populations, but that racial ideology played a much less important role in the Russian case compared to religious divisions and fears of cultural backsliding. This did not prevent relations between settlers and the ‘native’ population deteriorating markedly in the years before the First World War, resulting in large-scale rebellion in 1916

    Interrogating Genomic-Scale Data for Squamata (Lizards, Snakes, and Amphisbaenians) Shows no Support for Key Traditional Morphological Relationships

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    Genomics is narrowing uncertainty in the phylogenetic structure for many amniote groups. For one of the most diverse and species-rich groups, the squamate reptiles (lizards, snakes, and amphisbaenians), an inverse correlation between the number of taxa and loci sampled still persists across all publications using DNA sequence data and reaching a consensus on the relationships among them has been highly problematic. In this study, we use high-throughput sequence data from 289 samples covering 75 families of squamates to address phylogenetic affinities, estimate divergence times, and characterize residual topological uncertainty in the presence of genome-scale data. Importantly, we address genomic support for the traditional taxonomic groupings Scleroglossa and Macrostomata using novel machine-learning techniques. We interrogate genes using various metrics inherent to these loci, including parsimony-informative sites (PIS), phylogenetic informativeness, length, gaps, number of substitutions, and site concordance to understand why certain loci fail to find previously well-supported molecular clades and how they fail to support species-tree estimates. We show that both incomplete lineage sorting and poor gene-tree estimation (due to a few undesirable gene properties, such as an insufficient number of PIS), may account for most gene and species-tree discordance. We find overwhelming signal for Toxicofera, and also show that none of the loci included in this study supports Scleroglossa or Macrostomata. We comment on the origins and diversification of Squamata throughout the Mesozoic and underscore remaining uncertainties that persist in both deeper parts of the tree (e.g., relationships between Dibamia, Gekkota, and remaining squamates; among the three toxicoferan clades Iguania, Serpentes, and Anguiformes) and within specific clades (e.g., affinities among gekkotan, pleurodont iguanians, and colubroid families).This research was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo [grant number BIOTA-FAPESP 2011/50206-9 to H.Z.], National Science Foundation [grant numbers DEB-1257926 to F.T.B., DEB1441719 to R.A.P., DEB-1257610 to C.J.R.], and Australian Research Council Discovery [grant number DP120104146 to J.S.K. and S.C.D.]. F.G.G. benefited from a Postdoctoral grant from Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP grant number 2012/08661-3]

    Evaluating Housing Needs and Preferences of Generation Y in Malaysia

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    © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. In Malaysia, housing providers affect the planning system as housing industry constantly evolves to meet homebuyer needs. Generation Y has exhibited dissimilar housing needs compared to Generation X and Baby Boomer. Thus, housing developers seek to identify the current needs for young homebuyers to avoid experiencing unsold properties. This research aims to identify the fundamental housing needs and psychographic characteristics towards their housing preferences and future planning demands. A quantitative survey was used for collecting data and a statistical analysis was performed to evaluate research outcomes. This research will help local housing developers to understand Generation Y needs and preferences for the future housing demand
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