Time-resolved FRET fluorescence spectroscopy of visible fluorescent protein pairs

Förster resonance energy transfer (FRET) is a powerful method for obtaining information about small-scale lengths between biomacromolecules. Visible fluorescent proteins (VFPs) are widely used as spectrally different FRET pairs, where one VFP acts as a donor and another VFP as an acceptor. The VFPs are usually fused to the proteins of interest, and this fusion product is genetically encoded in cells. FRET between VFPs can be determined by analysis of either the fluorescence decay properties of the donor molecule or the rise time of acceptor fluorescence. Time-resolved fluorescence spectroscopy is the technique of choice to perform these measurements. FRET can be measured not only in solution, but also in living cells by the technique of fluorescence lifetime imaging microscopy (FLIM), where fluorescence lifetimes are determined with the spatial resolution of an optical microscope. Here we focus attention on time-resolved fluorescence spectroscopy of purified, selected VFPs (both single VFPs and FRET pairs of VFPs) in cuvette-type experiments. For quantitative interpretation of FRET–FLIM experiments in cellular systems, details of the molecular fluorescence are needed that can be obtained from experiments with isolated VFPs. For analysis of the time-resolved fluorescence experiments of VFPs, we have utilised the maximum entropy method procedure to obtain a distribution of fluorescence lifetimes. Distributed lifetime patterns turn out to have diagnostic value, for instance, in observing populations of VFP pairs that are FRET-inactiv

State marionettes, phantom organisations or genuine movements?

Of all the rural social movements in the world, those in post-socialist Russia have been considered to be among the weakest. Nevertheless, triggered by the neo-liberal reforms in the countryside, state attention to agriculture and rising land conflicts, new social movement organisations with a strong political orientation are emerging in Russia today. This sudden burst of civil activity, however, raises questions as to how genuine and independent the emerging organisations are. Our research shows that many rural movements, agricultural associations, farm unions and rural political parties lack constituency, support the status quo and/or are actually counterfeits (what we call 'phantom movement organisations'). With this analysis, we aim to explain the nature of social movements in the post-Soviet countryside and offer an original contribution to the theory on and practice of rural social movements

Structural Changes of Yellow Cameleon Domains Observed by Quantitative FRET Analysis and Polarized Fluorescence Correlation Spectroscopy

Förster resonance energy transfer (FRET) is a widely used method for monitoring interactions between or within biological macromolecules conjugated with suitable donor-acceptor pairs. Donor fluorescence lifetimes in absence and presence of acceptor molecules are often measured for the observation of FRET. However, these lifetimes may originate from interacting and noninteracting molecules, which hampers quantitative interpretation of FRET data. We describe a methodology for the detection of FRET that monitors the rise time of acceptor fluorescence on donor excitation thereby detecting only those molecules undergoing FRET. The large advantage of this method, as compared to donor fluorescence quenching method used more commonly, is that the transfer rate of FRET can be determined accurately even in cases where the FRET efficiencies approach 100% yielding highly quenched donor fluorescence. Subsequently, the relative orientation between donor and acceptor chromophores is obtained from time-dependent fluorescence anisotropy measurements carried out under identical conditions of donor excitation and acceptor detection. The FRET based calcium sensor Yellow Cameleon 3.60 (YC3.60) was used because it changes its conformation on calcium binding, thereby increasing the FRET efficiency. After mapping distances and orientation angles between the FRET moieties in YC3.60, cartoon models of this FRET sensor with and without calcium could be created. Independent support for these representations came from experiments where the hydrodynamic properties of YC3.60 under ensemble and single-molecule conditions on selective excitation of the acceptor were determined. From rotational diffusion times as found by fluorescence correlation spectroscopy and consistently by fluorescence anisotropy decay analysis it could be concluded that the open structure (without calcium) is flexible as opposed to the rather rigid closed conformation. The combination of two independent methods gives consistent results and presents a rapid and specific methodology to analyze structural and dynamical changes in a protein on ligand bindin

Oligarchs, megafarms and land reserves: understanding land grabbing in Russia

This paper seeks to unravel the political economy of large-scale land acquisitions in post-Soviet Russia. Russia falls neither in the normal category of ‘investor’ countries, nor in the category of ‘target’ countries. Russia has large ‘land reserves’, since in the 1990s much fertile land was abandoned. We analyse how particular Russia is with regards to the common argument in favour of land acquisitions, namely that land is available, unused or even unpopulated. With rapid economic growth, capital of Russian oligarchs in search of new frontiers, and the 2002 land code allowing land sales, land began to attract investment. Land grabbing expands at a rapid pace and in some cases, it results in dispossession and little or no compensation. This paper describes different land acquisitions strategies and argues that the share-based land rights distribution during the 1990s did not provide security of land tenure to rural dwellers. Emerging rural social movements try to form countervailing powers but with limited success. Rich land owners easily escape the implementation of new laws on controlling underutilized land, while there is a danger that they enable eviction with legal measures of rural dwellers. In this sense Russia appears to be a ‘normal’ case in the land grab debate

Is Russia the emerging global ‘breadbasket’?

Its rise to the top group of global wheat exporters, the abundance of abandoned land, assumed yield gaps and the apparent ‘success’ of agroholdings, have nurtured expectations of Russia becoming a global ‘breadbasket’. It is argued here that becoming a global breadbasket is hindered by substantial costs of re-cultivation abandoned land, management and financial problems of megafarms and agroholdings, lack of infrastructure for exports and increased domestic demand for feed grains, as input for the meat sector. Furthermore, as Russian wheat production is extremely volatile it might increase global price volatility, rather than contributing to global food security

The re-emerging peasantry in Russia.'Peasants-against-their-own will', 'Summertime peasants'and 'Peasant-farmers'

Abstract This paper aims at conceptualising the re-emerging Russian peasantry by looking at objective characteristics (land use, production mode, and market relations) and subjective ones (peasant identity, land attachment, and cross-generational transfer of peasant culture) of the contemporary rural population, involved in individualized agricultural production. We argue that the post-Soviet transition in Russia is causing a re-emergence of the peasantry, albeit in a very fragmented manner. Three types of ‘peasants’ are being distinguished: (1) ‘peasants-against-their-own-will’, who were part of the former collective and state farms, continuing their production on subsidiary household plots; (2) ‘summertime peasants’ of urban origin, who produce on their dachas plots in the weekend and holidays; and (3) subsistence-oriented ‘peasant-farmers’. We conclude that land attachment of the post-Soviet peasantry has still a strong collective component, while peasant identity is weakly developed, as well as cross-generational transfer of peasant values. The re-peasantisation is therefore only partial, with fragmented communities, and a near-absence of social capital, which is necessary to defend rural and peasant communities in the long run

"Quiet Food Sovereignty” as Food Sovereignty without Movements? Understanding Food Sovereignty in Post-Socialist Russia

What does food sovereignty look like in settings where rural social movements are weak or non-existent, such as in countries with post-socialist, semi-authoritarian regimes? Focusing on Russia, we present a divergent form of food sovereignty. Building on the concept of ‘quiet sustainability’, we present a dispersed, muted, but clearly bottom-up variant we term ‘quiet food sovereignty’. In the latter, the role of the very productive smallholdings is downplayed by the state and partly by the smallholders themselves. Those smallholdings are not seen as an alternative to industrial agriculture, but subsidiary to it (although superior in terms of sociality and healthy, environmentally friendly produce). As such, ‘quiet food sovereignty’ deviates from the overt struggle frequently associated with food sovereignty. We discuss the prospects of the ‘quiet food sovereignty’ to develop into a full food sovereignty movement, and stress the importance of studying implicit everyday forms of food sovereignty

Mustafa Kemal'in Boğazlara dair görüşü

Taha Toros Arşivi, Dosya Adı: Milli Mücadele İstiklal Harbi GazetesiUnutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010