Repeatability estimates for milk coagulation traits and non-coagulation of milk in Finnish Ayrshire cows

Effects of systematic environmental factors and milk production and quality traits on milk coagulation properties (MCP), and on repeatability of those traits were estimated from 979 milk samples collected once a month over a period of 2 years from 83 Finnish Ayrshire cows. Estimation was based on a multitrait animal model and REML methodology. In addition, persistence of non-coagulation of milk in individual cows, and factors associated with it were established from a sub sample of 24 cows producing non-coagulating (NC) milk at least once. MCP were at their best during the first lactation, at the beginning and at the end of lactation, and during grazing seasons. Variation in MCP with systematic environmental factors was partly due to variation in composition and quality of milk, especially in pH and ln (somatic cell count, SCC). Coefficients of repeatability for milk coagulation time and curd firmness were 0.65 and 0.68. These estimates were of the same magnitude as those for protein content, but were higher than those for daily milk yield, fat content, pH, and SCC. Based on the repeatability estimates for the milk coagulation traits and effects of the environmental factors, cows should be sampled at least three times during a lactation to estimate reliably breeding values for the milk coagulation traits. A total of 10% of the milk samples did not coagulate in 30 min after addition of rennet. Cows that produced NC milk at least once (30% of the cows) could be classified into those that produced NC milk only a few times during a lactation and those that produced NC milk at almost every sampling. Based on logistic regression analyses, peak and mid-lactation, high milk yield, low protein and fat content and high pH increased the risk of non-coagulation of milk.     

Fabrication of photoactive heterostructures based on quantum dots decorated with Au nanoparticles

Silica based multifunctional heterostructures, exhibiting near infrared (NIR) absorption (650–1200 nm) and luminescence in the visible region, represent innovative nanosystems useful for diagnostic or theranostic applications. Herein, colloidal synthetic procedures are applied to design a photoactive multifunctional nanosystem. Luminescent silica (SiO₂) coated quantum dots (QDs) have been used as versatile nanoplatforms to assemble on their surface gold (Au) seeds, further grown into Au spackled structures. The synthesized nanostructures combine the QD emission in the visible region, and, concomitantly, the distinctive NIR absorption of Au nanodomains. The possibility of having multiple QDs in a single heterostructure, the SiO₂ shell thickness, and the extent of Au deposition onto SiO₂ surface have been carefully controlled. The work shows that a single QD entrapped in 16 nm thick SiO₂ shell, coated with Au speckles, represents the most suitable geometry to preserve the QD emission in the visible region and to generate NIR absorption from metal NPs. The resulting architectures present a biomedical potential as an effective optical multimodal probes and as promising therapeutic agents due to the Au NP mediated photothermal effect.     

Synthesis and optical properties of dyes encapsulated in gold hollow nanoshells

Gold nanomaterials are promising objects for applications in optics and medicine because of their unique properties related to the Surface Plasmon Resonances (SPR) phenomena. It is possible to tune these properties with the control of the size and shape of the nanomaterials. Gold hollow spheres nanomaterials are an interesting concept for encapsulation of either dyes or drugs. The study of their properties and their behavior in a bio-environment still remains scarce and some phenomena are still to be explained in particular regarding local field enhancement effect or quenching of their photophysical properties. In this work we describe a process allowing inclusion of optical dyes in gold nanoshells and evaluate the optical properties.     

Using context to improve the effectiveness of segmentation and targeting in e-commerce

In e-commerce, where competition is tough and customers’ preferences can change quickly, it is crucial for companies to segment customers and target marketing actions effectively. The process of segmentation and targeting is effective if the customers grouped into the same segment show the same behavior and reaction to marketing campaigns. However, the link between segmentation and targeting is often missing. Some research contributions have recently addressed this issue, by proposing approaches to build customer behavior models in each segment. However customers’ behavior can change with the context, such as in many e-commerce business applications. In these cases, building contextual models of behavior would provide better predictive performance and, in turn, better targeting. However, the problem of including context in a segmentation model and building predictive behavior model of each segment consistently is still an open issue. This research aims at providing an answer to the following research issue: how to include context in a segmentation model in order to build an effective predictive model of customer behavior of each segment. To this aim we identified three different approaches and compared them by a set of experiments across several settings. The first result is that one of the three approaches dominates the others in certain conditions in our experiments. Another important result is that the most accurate approach is not always the most efficient from a managerial perspective.     

Heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence of a rhodamine label at oxide-coated aluminum and silicon electrodes

This paper describes a heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence (HECL) of a rhodamine label. Thin oxide-film coated aluminum and silicon electrodes were modified with an aminosilane layer and derivatized with short, 15-mer oligonucleotides via diisothiocyanate coupling. Target oligonucleotides were conjugated with tetramethylrhodamine (TAMRA) dye at their amino modified 5′ end and hybridization was detected using HECL of TAMRA. Preliminary results indicate sensitivity down to picomolar level and low nonspecific adsorption. The sensitivity was better on oxide-coated silicon compared to oxide-coated aluminum electrodes and two-base pair mismatched hybrids were successfully discriminated. The experimental results presented here might be useful for the design of disposable electrochemiluminescent DNA biosensors.     

FEA evaluation of material stiffness changes for a polymer assisted 3D polycaprolactone/β-tricalcium phosphate scaffold in a mandibular defect reconstruction model

In bone regenerative engineering, the biomechanical performance of the scaffold at the bone-tissue interface is a key consideration. The evaluation of this parameter is a crucial step in designing, optimizing and manufacturing of bone substitute materials for clinical application, but is as yet comparatively unexplored. To this end, we utilized a novel polymer-assisted method to fabricate a three-dimensional (3D) Polycaprolactone/β-Tricalcium phosphate scaffold. The compressive modulus was measured and the data used to inform finite element analysis. The scaffolds achieved a maximum compressive moduli of 151 MPa, close to that of cortical bone. Further computational simulations were performed to determine the stresses and local scaffold adaptation profile, using data from computer tomography scans of the mandible. Local stresses were simulated based on the density changes in new bone forming in the scaffold at different stages of healing. The stress distribution in the mandible, scaffold center and scaffold interface were explored for a static load of 200 N, which corresponds to the load of adult mastication near the incisors. The analysis revealed that the maximum cross-sectional stress at the scaffold center and at the scaffold interface was 2.7 and 4.12 MPa respectively. The majority of the stress was localized in the bone of the mandible, with the scaffold bearing minimal loading at the start, but more over time as infiltration of more new bone progressed.     

Engineered Human Induced Pluripotent Cells Enable Genetic Code Expansion in Brain Organoids

Human induced pluripotent stem cell (hiPSC) technology has revolutionized studies on human biology. A wide range of cell types and tissue models can be derived from hiPSCs to study complex human diseases. Here, we use PiggyBac-mediated transgenesis to engineer hiPSCs with an expanded genetic code. We demonstrate that genomic integration of expression cassettes for a pyrrolysyl-tRNA synthetase (PylRS), pyrrolysyl-tRNA (PylT) and the target protein of interest enables site-specific incorporation of a non-canonical amino acid (ncAA) in response to an amber stop codon. Neural stem cells, neurons and brain organoids derived from the engineered hiPSCs continue to express the amber suppression machinery and produce ncAA-bearing reporter. The incorporated ncAA can serve as a minimal bioorthogonal handle for further modifications by labeling with fluorescent dyes. Site-directed ncAA mutagenesis will open a wide range of applications to probe and manipulate proteins in brain organoids and other hiPSC-derived cell types and complex tissue models.     

Identification of new acceptor specificities of glycosyltransferase R with the aid of substrate microarrays

Finding opportunities to construct sugar motifs and to transfer them to targets of biological relevance and rapid identification of glycosylation events are important goals for glycobiology and a field of increasing interest. Here we have applied an enzyme microarray screening system for the identification of new acceptor specificities of the glycosyltransferase R (GTFR) from Streptococcus oralis (E.C. 2.4.1.5), which was able to effect the synthesis of sugar motifs in short times and with low amounts of substrate. These observations resulted in the development of a convenient alpha-glycosylation by the non-Leloir glycosyltransferase GTFR, with sucrose as substrate and with different alcohols and amino acid derivatives as acceptors, for the synthesis of glycoethers and glycosylated amino acids not observed with the use of familiar GTFs with high sequence homology.     

Availability of Ferritin-Bound Iron to Enterobacteriaceae

The sequestration of iron in case of infection, termed nutritional immunity, is an established strategy of host defense. However, the interaction between pathogens and the mammalian iron storage protein ferritin is hitherto not completely understood. To better characterize the function of ferritin in Gram-negative infections, we incubated iron-starved cultures of Salmonella Typhimurium and knockout mutant strains defective for major iron uptake pathways or Escherichia coli with horse spleen ferritin or ionic iron as the sole iron source. Additionally, we added bovine superoxide dismutase and protease inhibitors to the growth medium to assess the effect of superoxide and bacterial proteases, respectively, on Salmonella proliferation and reductive iron release. Compared to free ionic iron, ferritin-bound iron was less available to Salmonella, but was still sufficient to significantly enhance the growth of the bacteria. In the absence of various iron acquisition genes, the availability of ferritin iron further decreased. Supplementation with superoxide dismutase significantly reduced the growth of the ΔentC knockout strain with holoferritin as the sole iron source in comparison with ionic ferrous iron. In contrast, this difference was not observed in the wildtype strain, suggesting that superoxide dismutase undermines bacterial iron uptake from ferritin by siderophore-independent mechanisms. Ferritin seems to diminish iron availability for bacteria in comparison to ionic iron, and its iron sequestering effect could possibly be enhanced by host superoxide dismutase activity.