Cellulose bead entrapped microbial cells for biotechnical applications

Immobilization of intact or pretreated microbial cells instead of partially purified enzymes offers several advantages. A novel method has been applied to entrap Actinoplanes missouriensis, Bacillus coagulans, Kluyveromyces fragilis, K. lactis, Saccharomyces cerevisiae, Serratia sp., and Streptomyces albus cells within α-cellulose beads, with activity recoveries of about 22 to 85%. The best results were obtained with S. albus for glucose isomerase and with S. cerevisiae for invertase. The application of entrapped glucose isomerase-active A. missouriensis cells to increase the sweetness of β-galactosidase-hydrolysed dairy products was investigated in detail. Pressure drop across the column reactor bed was negligible; the stability of the entrapped enzyme was highest at pH 7.5 in the presence of both Mg²⁺and Co²⁺, although Co²⁺could be omitted with little effect on performance; and the activity was drastically affected by Ca²⁺content of substrate due to competition with Mg²⁺. The reactor was successfully operated for more than 5 weeks for the isomerization of demineralized concentrated whey hydrolysate of 8% lactose, 23% galactose, and up to 36% added glucose to obtain a syrup of sweetness approaching that of sucrose.     

Colonization of a host tree by herbivorous insects under a changing climate

Climate warming has been predicted to increase the abundance of herbivorous insects. Together with concurrent poleward shifts in many insect species this may increase herbivore pressure on plants. However, the manner in which plants at higher latitudes become colonized by herbivorous insects in the future is unknown. We established a translocation experiment using 26 micropropagated silver birch Betula pendula genotypes from six populations originating from 60°N to 67°N, to study the susceptibility of the translocated birches to local herbivores. The birches were planted at three different latitudes in Finland (60°N, 62°N and 67°N). We studied the effect of source population and latitudinal translocation on herbivore density, species richness, and community composition among the genotypes growing in the same environmental conditions in two years; 2011 and 2012. The source population explained the variation in the herbivore density only in 2012, whereas latitudinal translocation did not affect herbivore density. Variation in species richness was not explained by the source population or by the latitudinal translocation. At two of the study sites, the similarity of the herbivore communities among the populations decreased with increasing latitudinal distance of the source populations, possibly because birch populations that grow geographically closer to each other are genetically more similar, and therefore support a more similar composition of the arthropod community. All birch genotypes were colonized by local herbivores, suggesting that as herbivores shift their ranges polewards, they are able to colonize novel host‐plant genotypes. This enables compositional changes in insect communities on their host plants in the future, which in turn, might affect total herbivory and eventually, plant growth.     

A Comparative Analysis of Genetic Differentiation across Six Shared Willow Host Species in Leaf- and Bud-Galling Sawflies

Genetic divergence and speciation in plant-feeding insects could be driven by contrasting selection pressures imposed by different plant species and taxa. While numerous examples of host-associated differentiation (HAD) have been found, the overall importance of HAD in insect diversification remains unclear, as few studies have investigated its frequency in relation to all speciation events. One promising way to infer the prevalence and repeatability of HAD is to estimate genetic differentiation in multiple insect taxa that use the same set of hosts. To this end, we measured and compared variation in mitochondrial COI and nuclear ITS2 sequences in population samples of leaf-galling Pontania and bud-galling Euura sawflies (Hymenoptera: Tenthredinidae) collected from six Salix species in two replicate locations in northern Fennoscandia. We found evidence of frequent HAD in both species complexes, as individuals from the same willow species tended to cluster together on both mitochondrial and nuclear phylogenetic trees. Although few fixed differences among the putative species were found, hierarchical AMOVAs showed that most of the genetic variation in the samples was explained by host species rather than by sampling location. Nevertheless, the levels of HAD measured across specific pairs of host species were not correlated in the two focal galler groups. Hence, our results support the hypothesis of HAD as a central force in herbivore speciation, but also indicate that evolutionary trajectories are only weakly repeatable even in temporally overlapping radiations of related insect taxa.     

MT1-MMP inactivates ADAM9 to regulate FGFR2 signaling and calvarial osteogenesis

MMP14 encodes a membrane-tethered metalloproteinase MT1-MMP, capable of remodeling the extracellular matrix and modulating receptors on the cell surface. Loss of MT1-MMP results in craniofacial abnormalities. Here we show that MT1-MMP forms a complex with FGFR2 and ADAM9 in osteoblasts and proteolytically inactivates ADAM9, hence protecting FGFR2 from ADAM9-mediated ectodomain shedding on the cell surface. In Mmp14-/- osteoblasts, FGF-induced proliferation and downstream signaling are specifically compromised, in conjunction with ADAM9 upregulation and FGFR2 shedding. The retarded parietal growth in Mmp14-/- embryos starts at 15.5 dpc, attributable to the impaired FGFR2 signaling due to increased shedding mediated by ADAM9. Adam9 depletion completely rescues the defective FGFR2 signaling and largely restores calvarial bone growth in Mmp14-/- embryos. These data reveal a regulatory paradigm for FGRF2 signaling and identify MT1-MMP as a critical negative modulator of ADAM9 activity to maintain FGFR2 signaling in calvarial osteogenesis.     

Transmembrane collagen XVII is a novel component of the glomerular filtration barrier

The kidney filtration barrier consists of the capillary endothelium, the glomerular basement membrane and the slit diaphragm localized between foot processes of neighbouring podocytes. We report that collagen XVII, a transmembrane molecule known to be required for epithelial adhesion, is expressed in podocytes of normal human and mouse kidneys and in endothelial cells of the glomerular filtration barrier. Immunoelectron microscopy has revealed that collagen XVII is localized in foot processes of podocytes and in the glomerular basement membrane. Its role in kidney has been analysed in knockout mice, which survive to birth but have high neonatal mortality and skin blistering and structural abnormalities in their glomeruli. Morphometric analysis has shown increases in glomerular volume fraction and surface densities of knockout kidneys, indicating an increased glomerular amount in the cortex. Collagen XVII deficiency causes effacement of podocyte foot processes; however, major slit diaphragm disruptions have not been detected. The glomerular basement membrane is split in areas in which glomerular and endothelial basement membranes meet. Differences in the expression of collagen IV, integrins α3 or β1, laminin α5 and nephrin have not been observed in mutant mice compared with controls. We propose that collagen XVII has a function in the attachment of podocyte foot processes to the glomerular basement membrane. It probably contributes to podocyte maturation and might have a role in glomerular filtration.     

Étude de la cohorte nord-finlandaise de 1966: facteurs prédictifs et conséquences de la schizophrénie

Subtle motor, emotional, cognitive and behavioural abnormalities are often present in apparently healthy children and adolescents who later develop schizophrenia. This suggests that some aspects of causation are established long before psychosis becomes manifest. We aim to assess the factors contributing to the development of schizophrenia focusing mainly on genetic factors, pregnancy and delivery complications, early development and scholastic performance, as well as later educational, social and health consequences. This is done by reviewing the Northern Finland 1966 Birth Cohort, its scientific activities, publications and work in progress.