MNE’s Regional Location Choice - A Comparative Perspective on East Germany, the Czech Republic and Poland

The focus of this article is the empirical identification of factors influencing Foreign Direct Investment (FDI) in transition economies on a regional level (NUTS 2). The analysis is designed as benchmark between three neighboring post-communist regions, i.e. East Germany, the Czech Republic and Poland. Their different transition paths have not only resulted in economic differences. We can also observe today that the importance of pull factors for FDI varies significantly across the regions. This analysis shows that in comparison with Poland and the Czech Republic, East Germany’s major benefit is its purchasing power, its geographical proximity to West European markets, and its modern infrastructure. Furthermore, the analysis suggests that intra-industry linkages such as specialization and agglomeration economies are relevant factors for the location decision of foreign investors. This result can help to explain the regional divergence of FDI streams in transition economies.multinational enterprises, international business, regional economic activity: growth, development, and changes, discrete choice

Subnanoliter enzymatic assays on microarrays

Many areas of research today are based on enzymatic assays most of which are still performed as enzyme-linked immunosorbent assays in microtiter plates. The demand for highly parallel screening of thousands of samples eventually led to a miniaturization and automation of these assays. However, the final transfer of enzymatic assays from a microtiter-based technology to microarrays has proven to be difficult for various reasons, such as the inability to maintain unbound reaction products on the spot of reaction or the missing capability of multiplexing. Here, we have conducted multiplex enzymatic assays in subnanoliter volumes on a single microarray using the multiple spotting technology. We were able to measure enzymatic activity with a sensitivity down to 35 enzyme molecules, applying only conventional flat microarray surfaces and standard microarray hardware. We have performed assays of inhibition and applied this format for the detection of prognostic markers, such as cathepsin D. The new approach allows the rapid and multiplex screening of thousands of samples on a single microarray with applications in drug screening, metagenomics, and high-throughput enzyme assays

Bacterial protein microarrays for identification of new potential diagnostic markers for Neisseria meningitidis infections

Neisseria meningitidis is the most common cause of meningitis and causes epidemic outbreaks. One trait of N. meningitidis, which is associated with most of the currently recognized virulence determinants, is the presence of phase-variable genes that are suspected to enhance its ability to cause an invasive disease. To detect the immune responses to phase-variable expressed proteins, we applied protein microarray technology for the screening of meningitis patient sera. We amplified all 102 known phase-variable genes from N. meningitidis serogroup B strain MC58 by polymerase chain reaction and subcloned them for expression in Escherichia coli. With this approach, we were able to express and purify 67 recombinant proteins representing 66% of the annotated genes. These were spotted robotically onto coated glass slides to generate protein microarrays, which were screened using 20 sera of patients suffering from meningitis, as well as healthy controls. From these screening experiments, 47 proteins emerged as immunogenic, exhibiting a variable degree of seroreactivity with some of the patient sera. Nine proteins elicited an immune response in more than three patients, with one of them, the phase-variable opacity protein OpaV (NMB0442), showing responses in 11 patient sera. This is the first time that protein microarray technology has been applied for the investigation of genetic phase variation in pathogens. The identification of disease-specific proteins is a significant target in biomedical research, as such proteins may have medical, diagnostic, and commercial potential as disease markers

Clonally resolved single-cell multi-omics identifies routes of cellular differentiation in acute myeloid leukemia

Inter-patient variability and the similarity of healthy and leukemic stem cells (LSCs) have impeded the characterization of LSCs in acute myeloid leukemia (AML) and their differentiation landscape. Here, we introduce CloneTracer, a novel method that adds clonal resolution to single-cell RNA-seq datasets. Applied to samples from 19 AML patients, CloneTracer revealed routes of leukemic differentiation. Although residual healthy and preleukemic cells dominated the dormant stem cell compartment, active LSCs resembled their healthy counterpart and retained erythroid capacity. By contrast, downstream myeloid progenitors constituted a highly aberrant, disease-defining compartment: their gene expression and differentiation state affected both the chemotherapy response and leukemia's ability to differentiate into transcriptomically normal monocytes. Finally, we demonstrated the potential of CloneTracer to identify surface markers misregulated specifically in leukemic cells. Taken together, CloneTracer reveals a differentiation landscape that mimics its healthy counterpart and may determine biology and therapy response in AML

Mol Cell Proteom

Due to the success of DNA microarrays and the growing numbers of available protein expression clones, protein microarrays have become more and more popular for the high throughput screening of protein interactions. However, the widespread applicability of protein microarrays is currently hampered by the large effort associated with their production. Apart from the requirement for a protein expression library, expression and purification of the proteins themselves and the lacking stability of many proteins remain the bottleneck. Here we present an approach that allows the generation of high density protein microarrays from unbound DNA template molecules on the chip. It is based on the multiple spotting technique and comprises the deposition of a DNA template in a first spotting step and the transfer of a cell-free transcription and translation mixture on top of the same spot in a second spotting step. Using wild-type green fluorescent protein as a model protein, we demonstrated the time and template dependence of this coupled transcription and translation and showed that enough protein was produced to yield signals that were comparable to 300 µg/ml spotted protein. Plasmids as well as unpurified PCR products can be used as templates, and as little as 35 fg of PCR product (~22,500 molecules) were sufficient for the detectable expression of full-length wild-type green fluorescent protein in subnanoliter volumes. We showed that both aminopropyltrimethoxysilane and nickel chelate surfaces can be used for capture of the newly synthesized proteins. Surprisingly we observed that nickel chelate-coated slides were binding the newly synthesized proteins in an unspecific manner. Finally we adapted the system to the high throughput expression of libraries by designing a single primer pair for the introduction of the required T7 promoter and demonstrated the in situ expression using 384 randomly chosen clones

J. Chromatogr. A

The performance of protein and antibody microarrays is dependent on various factors, one of which is the use of an appropriate microarray surface for the immobilisation of either protein or antibody samples. We have investigated the properties of seven new surfaces in the context of both protein and antibody microarray technology. We have demonstrated the functionality of all new slide coatings and investigated the mean signal to spotted concentration ratio, determined detection limits and calculated coefficients of variation. Moreover, new concepts for slide coatings such as dendrimer and poly(ethylene glycol)-epoxy slides were evaluated and improved qualities of novel slide surfaces were observed. Optimal slide coatings for antibody and protein chips were proposed and the requirements for both technologies were discussed