| 1. |
- Elsik, Christine G., et al.
(author)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Journal article (peer-reviewed)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 2. |
- Follows, David, et al.
(author)
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Co-adsorption of beta-casein and calcium phosphate nanoclusters (CPN) at hydrophilic and hydrophobic solid-solution interfaces studied by neutron reflectometry
- 2011
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In: Food Hydrocolloids. - : Elsevier BV. - 1873-7137 .- 0268-005X. ; 25:4, s. 724-733
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Conference paper (peer-reviewed)abstract
- Neutron reflectometry was used to study the co-adsorption of calcium phosphate nanoclusters (CPN) and beta-casein at hydrophobized and hydrophilic silica-water interfaces. The structural characteristics of the adsorbed layer were determined from neutron reflectivity curves analysed with multi-layer optical models. We used a highly specific proteolytic enzyme, endoproteinase Asp-N in conjunction with a single neutron contrast to verify the model of the protein layer structure. The results showed that the calcium phosphate nanoclusters profoundly affected the rate of adsorption and structure of the interface compared to the adsorption of beta-casein alone and for the hydrophobic interface the effects depended on the point at which the nanoclusters were added. It is proposed that the nanoclusters become surface active because whole beta-casein molecules can replace one or more of the hydrophilic peptides in the shell of the nanoclusters. (C) 2010 Elsevier Ltd. All rights reserved.
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| 3. |
- Gordon, Line J., et al.
(author)
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Rewiring food systems to enhance human health and biosphere stewardship
- 2017
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In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 12:10
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Journal article (other academic/artistic)abstract
- Food lies at the heart of both health and sustainability challenges. We use a social-ecological framework to illustrate how major changes to the volume, nutrition and safety of food systems between 1961 and today impact health and sustainability. These changes have almost halved undernutrition while doubling the proportion who are overweight. They have also resulted in reduced resilience of the biosphere, pushing four out of six analysed planetary boundaries across the safe operating space of the biosphere. Our analysis further illustrates that consumers and producers have become more distant from one another, with substantial power consolidated within a small group of key actors. Solutions include a shift from a volume-focused production system to focus on quality, nutrition, resource use efficiency, and reduced antimicrobial use. To achieve this, we need to rewire food systems in ways that enhance transparency between producers and consumers, mobilize key actors to become biosphere stewards, and re-connect people to the biosphere.
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| 4. |
- Holt, Carl, et al.
(author)
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Mineralisation of soft and hard tissues and the stability of biofluids.
- 2014
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In: Journal of Structural Biology. - : Elsevier BV. - 1095-8657 .- 1047-8477. ; 185:3, s. 383-396
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Journal article (peer-reviewed)abstract
- Evidence is provided from studies on natural and artificial biofluids that the sequestration of amorphous calcium phosphate by peptides or proteins to form nanocluster complexes is of general importance in the control of physiological calcification. A naturally occurring mixture of osteopontin peptides was shown, by light and neutron scattering, to form calcium phosphate nanoclusters with a core-shell structure. In blood serum and stimulated saliva, an invariant calcium phosphate ion activity product was found which corresponds closely in form and magnitude to the ion activity product observed in solutions of these osteopontin nanoclusters. This suggests that types of nanocluster complexes are present in these biofluids as well as in milk. Precipitation of amorphous calcium phosphate from artificial blood serum, urine and saliva was determined as a function of pH and the concentration of osteopontin or casein phosphopeptides. The position of the boundary between stability and precipitation was found to agree quantitatively with the theory of nanocluster formation. Artificial biofluids were prepared that closely matched their natural counterparts in calcium and phosphate concentrations, pH, saturation, ionic strength and osmolality. Such fluids, stabilised by a low concentration of sequestering phosphopeptides, were found to be highly stable and may have a number of beneficial applications in medicine.
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| 5. |
- Holt, Kristoffer, 1976-, et al.
(author)
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Photos on facebook : Photos on Facebook – 24 youths about social visual communication on Facebook
- 2010
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Conference paper (peer-reviewed)abstract
- This paper deals with the question why youths are publishing photos digitally and how they think about making private photographs public. It also looks into differences between men and women regarding their attitude towards publishing photos in this way.By focus group interviews, we have examined how 18-year-old high school students in Sweden reflect over photos and photo publishing on the online social networkFacebook. Three focus groups consisting of women and three focus groups consisting of men were asked questions about four different themes: mediatization, integrity, self-presentation and ethics.The results show that the youths live mediated lives and that there is, to them, an intimate link between their digital selves and their real life-selves. With the use of photographs, they re-tell events from real life on Facebook. They also use photographs to construct their digital selves, and these images are seen as important for how they are perceived by others. The girls in the focus groups claim that they publish more photos of themselves than the boys, and are more conscious of how they appear on these photos. The youths do take in mind how an unknown public can take part of the information that is digitally gathered about them, and therefore defend their integrity on Facebook since they want to control the existence of the photos they are occurring on. Furthermore, the youths show an understanding of the ethical dilemmas involved, but do not see this as a problem since they claim to often know the publisher of these photos, and express that since they only upload photos of their friends, they would never publish unethical photos on Facebook themselves.
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| 6. |
- Lenton, Samuel, et al.
(author)
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A review of the biology of calcium phosphate sequestration with special reference to milk.
- 2015
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In: Dairy Science & Technology. - : Springer Science and Business Media LLC. - 1958-5586 .- 1958-5594. ; 95:1, s. 3-14
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Research review (peer-reviewed)abstract
- In milk, a stable fluid is formed in which sequestered nanoclusters of calcium phosphate are substructures in casein micelles. As a result, calcium and phosphate concentrations in milk can be far in excess of their solubility. Variations of calcium, phosphate and casein concentrations in milks, both within and among species, are mainly due to the formation of the nanocluster complexes. Caseins evolved from tooth and bone proteins well before the evolution of lactation. It has therefore been suggested that the role of caseins in milk is an adaptation of an antecedent function in the control of some aspect of biomineralisation. There is new evidence that nanocluster-type complexes are also present in blood serum and, by implication, in many other closely related biofluids. Because such fluids are stable but nevertheless supersaturated with respect to the bone and tooth mineral hydroxyapatite, they allow soft and mineralised tissues to co-exist in the same organism with relative ease. An appreciable concentration of nanocluster complexes exists in fresh saliva. Such saliva may stabilise tooth mineral and help to repair demineralised lesions. In the extracellular matrix of bone, nanocluster complexes may be involved in directing the amorphous calcium phosphate to intrafibrillar spaces in collagen where they can mature into oriented apatite crystals. Thus, evidence is accumulating that calcium phosphate sequestration by phosphopeptides to form equilibrium complexes, first observed in milk, is more generally important in the control of physiological calcification.
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| 7. |
- Lenton, Samuel, et al.
(author)
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Effect of Phosphorylation on a Human-like Osteopontin Peptide
- 2017
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In: Biophysical Journal. - : Elsevier BV. - 0006-3495. ; 112:8, s. 1586-1596
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Journal article (peer-reviewed)abstract
- The last decade established that the dynamic properties of the phosphoproteome are central to function and its modulation. The temporal dimension of phosphorylation effects remains nonetheless poorly understood, particularly for intrinsically disordered proteins. Osteopontin, selected for this study due to its key role in biomineralization, is expressed in many species and tissues to play a range of distinct roles. A notable property of highly phosphorylated isoforms of osteopontin is their ability to sequester nanoclusters of calcium phosphate to form a core-shell structure, in a fluid that is supersaturated but stable. In Biology, this process enables soft and hard tissues to coexist in the same organism with relative ease. Here, we extend our understanding of the effect of phosphorylation on a disordered protein, the recombinant human-like osteopontin rOPN. The solution structures of the phosphorylated and unphosphorylated rOPN were investigated by small-angle x-ray scattering and no significant changes were detected on the radius of gyration or maximum interatomic distance. The picosecond-to-nanosecond dynamics of the hydrated powders of the two rOPN forms were further compared by elastic and quasi-elastic incoherent neutron scattering. Phosphorylation was found to block some nanosecond side-chain motions while increasing the flexibility of other side chains on the faster timescale. Phosphorylation can thus selectively change the dynamic behavior of even a highly disordered protein such as osteopontin. Through such an effect on rOPN, phosphorylation can direct allosteric mechanisms, interactions with substrates, cofactors and, in this case, amorphous or crystalline biominerals.
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| 8. |
- Lenton, Samuel, et al.
(author)
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Structural biology of calcium phosphate nanoclusters sequestered by phosphoproteins
- 2020
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In: Crystals. - : MDPI AG. - 2073-4352. ; 10:9
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Research review (peer-reviewed)abstract
- Biofluids that contain stable calcium phosphate nanoclusters sequestered by phosphopeptides make it possible for soft and hard tissues to co-exist in the same organism with relative ease. The stability diagram of a solution of nanocluster complexes shows how the minimum concentration of phosphopeptide needed for stability increases with pH. In the stable region, amorphous calcium phosphate cannot precipitate. Nevertheless, if the solution is brought into contact with hydroxyapatite, the crystalline phase will grow at the expense of the nanocluster complexes. The physico-chemical principles governing the formation, composition, size, structure, and stability of the complexes are described. Examples are given of complexes formed by casein, osteopontin, and recombinant phosphopeptides. Application of these principles and properties to blood serum, milk, urine, and resting saliva is described to show that under physiological conditions they are in the stable region of their stability diagram and so cannot cause soft tissue calcification. Stimulated saliva, however, is in the metastable region, consistent with its role in tooth remineralization. Destabilization of biofluids, with consequential ill-effects, can occur when there is a failure of homeostasis, such as an increase in pH without a balancing increase in the concentration of sequestering phosphopeptides.
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| 9. |
- Lenton, Samuel, et al.
(author)
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Structural studies of hydrated samples of amorphous calcium phosphate and phosphoprotein nanoclusters.
- 2016
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In: European Biophysics Journal. - : Springer Science and Business Media LLC. - 1432-1017 .- 0175-7571.
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Journal article (peer-reviewed)abstract
- There are abundant examples of nanoclusters and inorganic microcrystals in biology. Their study under physiologically relevant conditions remains challenging due to their heterogeneity, instability, and the requirements of sample preparation. Advantages of using neutron diffraction and contrast matching to characterize biomaterials are highlighted in this article. We have applied these and complementary techniques to search for nanocrystals within clusters of calcium phosphate sequestered by bovine phosphopeptides, derived from osteopontin or casein. The neutron diffraction patterns show broad features that could be consistent with hexagonal hydroxyapatite crystallites smaller than 18.9 Å. Such nanocrystallites are, however, undetected by the complementary X-ray and FTIR data, collected on the same samples. The absence of a distinct diffraction pattern from the nanoclusters supports the generally accepted amorphous calcium phosphate structure of the mineral core.
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| 10. |
- Ossowski, Sofie, et al.
(author)
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Aggregation Behavior of Bovine kappa- and beta-Casein Studied with Small Angle Neutron Scattering, Light Scattering, and Cryogenic Transmission Electron Microscopy
- 2012
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:38, s. 13577-13589
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Journal article (peer-reviewed)abstract
- In the native bovine casein micelle the calcium sensitive caseins (alpha(S1)-, alpha(S2)- and beta-casein) sequester amorphous calcium phosphate in nanometer-sized clusters, whereas the calcium-insensitive K-casein limits the growth of the micelle. In this paper, we further investigate the self-association of kappa- and beta-casein, which are two of the key proteins that control the substructure of the milk casein micelle, using neutron and light scattering techniques and cryogenic transmission electron microscopy. Results demonstrate that K-casein can, apart from the known self-assembly, form amyloid-like fibrils already at temperatures of 25 degrees C when subject to agitation. This extended aggregation behavior of kappa-casein is inhibited by beta-casein, as reported by others. These findings have implications for the structure and stability of casein micelles. The neutron scattering data was used to gain information on the self-assembly structure of kappa-casein. beta-Casein shows similar self-association behavior as kappa-casein, but unlike kappa-casein, the self-association exhibits temperature dependence within the studied temperatures (6 and 25 degrees C). Here, we will discuss our extended study of the known self-assembly of casein in the context of the fibrillation of kappa-casein.
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| 11. |
- Wang, Qian, et al.
(author)
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Salt partition, ion equilibria, and the structure, composition, and solubility of micellar calcium phosphate in bovine milk with added calcium salts
- 2020
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302. ; 103:11, s. 9893-9905
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Journal article (peer-reviewed)abstract
- Increasing dietary calcium has been suggested to have a range of health benefits, such as reducing the risk of osteoporosis and hypertension. However, producing calcium-fortified products is challenging due to the destabilizing effect caused by added calcium. We provide new data on the effect of adding either calcium gluconate or calcium lactate at up to 50 mM on the partition of salts and the structure and solubility of micellar calcium phosphate (MCP). The empirical chemical formula of the MCP in milk with added calcium was Ca(HPO4)0.6(PO4)0.267, similar to that previously reported for the MCP in native bovine casein micelles. Ion equilibria calculations showed that the solubility of the MCP was decreased as measured by an increase in negative logarithm of the solubility constant (pKS) from 6.8 to 7.3 ± 0.1 and 7.5 ± 0.1 for milk with added calcium gluconate and calcium lactate, respectively. No substantial change in the amorphous structure of the MCP was observed by either X-ray powder diffraction or infrared spectroscopy of dried casein micelles as a result of added calcium. The conclusion is that the added calcium caused an increase in the concentration of the MCP and decreased its solubility without changing its amorphous structure or chemical composition.
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