Scandinavia was one of the last geographic areas in Europe to become habitable for humans after the Last Glacial Maximum (LGM). However, the routes and genetic composition of these postglacial migrants remain unclear. We sequenced the genomes, up to 57× coverage, of seven hunter-gatherers excavated across Scandinavia and dated from 9,500–6,000 years before present (BP). Surprisingly, among the Scandinavian Mesolithic individuals, the genetic data display an east–west genetic gradient that opposes the pattern seen in other parts of Mesolithic Europe. Our results suggest two different early postglacial migrations into Scandinavia: initially from the south, and later, from the northeast. The latter followed the ice-free Norwegian north Atlantic coast, along which novel and advanced pressure-blade stone-tool techniques may have spread. These two groups met and mixed in Scandinavia, creating a genetically diverse population, which shows patterns of genetic adaptation to high latitude environments. These potential adaptations include high frequencies of low pigmentation variants and a gene region associated with physical performance, which shows strong continuity into modern-day northern Europeans.

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An expression system to allow targeting of heterologous proteins to the cell surface of Staphylococcus xylosus, a coagulase-negative gram-positive bacterium, is described. The expression of recombinant gene fragments, fused between gene fragments encoding the signal peptide and the cell surface-binding regions of staphylococcal protein A, targets the resulting fusion proteins to the outer bacterial cell surface via the membrane-anchoring region and the highly charged cell wall-spanning region of staphylococcal protein A. The expression system was used to secrete fusion proteins containing sequences from a malaria blood-stage antigen and a streptococcal albumin-binding receptor to the cell surface of S. xylosus. Analysis of the recombinant cells by immunogold staining and immunofluorescence revealed that both the receptor and the malaria peptide were properly processed and exposed on the surface of the host cells. However, only approximately 40 to 50% of the recombinant cells were strongly stained with antiserum reactive with the albumin-binding receptor, while approximately 10 to 15% of the cells were stained with antiserum reactive with the malaria peptide. The incomplete staining of some of the cells suggests steric effects that make the recombinant fusion proteins inaccessible to the reactive antibodies because ofvariable cell wall structures. However, the results demonstrate for the first time that recombinant techniques can be used to express heterologous receptors and immunogens on the surface of gram-positive cells.

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By using an improved analytical method, we have confirmed that young healthy children have higher fCP concentrations than healthy adults. We, for the first time, report reference values for fEDN concentrations in a pediatric population. The proposed nomograms and reference values for fCP and fEDN are aimed at facilitating the applicability of biomarkers for both neutrophil- and eosinophil-mediated intestinal inflammation in children in clinical practice.