Bottom-up assembly of functional intracellular synthetic organelles by droplet-based microfluidics

Bottom-up synthetic biology has directed most efforts toward the construction of artificial compartmentalized systems that recreate living cell functions in their mechanical, morphological, or metabolic characteristics. However, bottom-up synthetic biology also offers great potential to study subcellular structures like organelles. Because of their intricate and complex structure, these key elements of eukaryotic life forms remain poorly understood. Here, the controlled assembly of lipid enclosed, organelle-like architectures is explored by droplet-based microfluidics. Three types of giant unilamellar vesicles (GUVs)-based synthetic organelles (SOs) functioning within natural living cells are procedured: (A) synthetic peroxisomes supporting cellular stress-management, mimicking an organelle innate to the host cell by using analogous enzymatic modules; (B) synthetic endoplasmic reticulum (ER) as intracellular light-responsive calcium stores involved in intercellular calcium signalling, mimicking an organelle innate to the host cell but utilizing a fundamentally different mechanism; and (C) synthetic magnetosomes providing eukaryotic cells with a magnetotactic sense, mimicking an organelle that is not natural to the host cell but transplanting its functionality from other branches of the phylogenetic tree. Microfluidic assembly of functional SOs paves the way for high-throughput generation of versatile intracellular structures implantable into living cells. This in-droplet SO design may support or expand cellular functionalities in translational nanomedicine

Nature and origin of secondary mineral coatings on volcanic rocks of the Black Mountain, Stonewall Mountain, and Kane Springs Wash volcanic centers, southern, Nevada

The following subject areas are covered: (1) genetic, spectral, and LANDSAT Thematic Mapper imagery relationship between desert varnish and tertiary volcanic host rocks, southern Nevada; (2) reconnaissance geologic mapping of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada, using multispectral thermal infrared imagery; (3) interregional comparisons of desert varnish; and (4) airborne scanner (GERIS) imagery of the Kane Springs Wash Volcanic Center, Lincoln County, Nevada

The political marketplace: a framework and toolkit for analyzing transactional politics in conflict-affected countries

This memo summarizes the research of the Conflict Research Programme (CRP) on the logic of the political marketplace and how it relates to war, peace, democracy and ‘what works’ to reduce violence in conflict-affected fragile states. It shows the utility of interpreting political systems and the actions of members of political elites in accordance with the standing assumption that they pursue the goal of political viability (survival and enhancement) in accordance with a legible logic of monetized transactional politics. The resulting framework is useful for civic and humanitarian actors in turbulent countries and for external policymakers seeking to promote stability, peace, democracy and development, insofar as it provides a clear-eyed evaluation of the challenges and dangers facing reformers

Binding of His-tagged fluorophores to lipid bilayers and giant vesicles

His-tagged molecules can be attached to lipid bilayers via certain anchor lipids, a method that has been widely used for the biofunctionalization of membranes and vesicles. To measure the coverage by the membrane-bound molecules, it is useful to study molecules that are fluorescent as well. Here, we use two such molecules, green fluorescence protein (GFP) and green-fluorescent fluorescin isothiocyanate (FITC), both of which are tagged with a chain of six histidines that bind to achor lipids within the bilayers. This His-tag is much smaller in size than the GFP molecule but somewhat larger than the FITC dye. The lipid bilayers form giant unilamellar vesicles (GUVs), the behavior of which can be directly observed in the optical microscope. Several protocols for the preparation of GUVs have been developed. We apply and compare three well-established protocols based on polyvinyl alcohol (PVA) hydrogel swelling, electroformation on platinum wires, and electroformation on indium tin oxide (ITO) glass. For the same nanomolar concentration in the exterior solution, the coverage by His-tagged FITC is much lower than the one by His-tagged GFP. However, for both GFP and FITC, we find that the binding of the His-tagged molecules to the anchor lipids depends strongly on the preparation method. The highest binding affinitiy is obtained for electroformation on platinum wires. PVA gel swelling gives rise to a somewhat smaller binding affinity whereas electroformation on ITO glass leads to essentially no binding. Furthermore, the binding affinitiy is also observed to depend on the pH of the aqueous solution, with a relatively weak and strong pH-dependence for His-tagged GFP and His-tagged FITC, respectively

Microstructured blood vessel surrogates reveal structural tropism of motile malaria parasites

Plasmodium sporozoites, the highly motile forms of the malaria parasite, are transmitted naturally by mosquitoes and traverse the skin to find, associate with, and enter blood capillaries. Research aimed at understanding how sporozoites select blood vessels is hampered by the lack of a suitable experimental system. Arrays of uniform cylindrical pillars can be used to study small cells moving in controlled environments. Here, an array system displaying a variety of pillars with different diameters and shapes is developed in order to investigate how Plasmodium sporozoites associate to the pillars as blood vessel surrogates. Investigating the association of sporozoites to pillars in arrays displaying pillars of different diameters reveals that the crescent-shaped parasites prefer to associate with and migrate around pillars with a similar curvature. This suggests that after transmission by a mosquito, malaria parasites may use a structural tropism to recognize blood capillaries in the dermis in order to gain access to the blood stream

A teaching unit on electric vehicles to foster students' decision-making competencies

According to the national education standards set by the standing Conference of Education Ministers in Germany in 2004, one of the central aims of science education in schools is to develop the competency of responsible decision-making. However, appropriate didactic and methodical concepts remain rare. Against this background, a targeted teaching unit for secondary schools including all teaching resources (worksheets, sample solutions, handouts, etc.) has been developed and evaluated. We have chosen electric vehicles as a contemporary context, since there seems to be no consensus in the public debate on this topic yet. Therefore, good arguments abound and can easily be found either for or against the new technology. As an introduction to the unit, students are asked to make a choice for one of two controversial, opposing articles presented to them. They are also asked to estimate how confident they are about their choice on a Likert scale. During the following lessons, students explore the topic not only through physical and technical principles, but also consider aspects outside the technical sphere. At the end students are asked to write their own composition in form of a newspaper article on the subject. The way they base their decisions on their arguments is analysed and assessed. This paper reports on the structure and the materials of the teaching unit as well as classroom experiences