13 research outputs found
Regulatory axes on food advertising to children on television
This article describes and evaluates some of the criteria on the basis of which food advertising to children on television could be regulated, including controls that revolve around the type of television programme, the type of product, the target audience and the time of day. Each of these criteria potentially functions as a conceptual device or "axis" around which regulation rotates. The article considers examples from a variety of jurisdictions around the world, including Sweden and Quebec. The article argues that restrictions centring on the time of day when a substantial proportion of children are expected to be watching television are likely to be the easiest for consumers to understand, and the most effective in limiting children's exposure to advertising
The evolution of a Gondwanan collisional orogen: A structural and geochronological appraisal from the Southern Granulite Terrane, South India
Gondwana amalgamated along a suite of Himalayan-scale collisional orogens, the roots of which lace the continents of Africa, South America, and Antarctica. The Southern Granulite Terrane of India is a generally well-exposed, exhumed, Gondwana-forming orogen that preserves a record of the tectonic evolution of the eastern margin of the East African Orogen during the Ediacaran-Cambrian (circa 600–500 Ma) as central Gondwana formed. The deformation associated with the closure of the Mozambique Ocean and collision of the Indian and East African/Madagascan cratonic domains is believed to have taken place along the southern margin of the Salem Block (the Palghat-Cauvery Shear System, PCSS) in the Southern Granulite Terrane. Investigation of the structural fabrics and the geochronology of the high-grade shear zones within the PCSS system shows that the Moyar-Salem-Attur shear zone to the north of the PCSS system is early Paleoproterozoic in age and associated with dextral strike-slip motion, while the Cauvery shear zone (CSZ) to the south of the PCSS system can be loosely constrained to circa 740–550 Ma and is associated with dip-slip dextral transpression and north side-up motion.To the south of the proposed suture zone (the Cauvery shear zone), the structural fabrics of the Northern Madurai Block suggest four deformational events (D1–D4), some of which are likely to be contemporaneous. The timing of high pressure-ultrahigh temperature metamorphism and deformation (D1–D3) in the Madurai Block (here interpreted as the southern extension of Azania) is constrained to circa 550–500 Ma and interpreted as representing collisional orogeny and subsequent orogenic collapse of the eastern margin of the East African Orogen. The disparity in the nature of the structural fabrics and the timing of the deformation in the Salem and the Madurai Blocks suggest that the two experienced distinct tectonothermal events prior to their amalgamation along the Cauvery shear zone during the Ediacaran/Cambrian
Earth's Continental Lithosphere Through Time
International audienceThe record of the continental lithosphere is patchy and incomplete; no known rock is older than 4.02 Ga, and less than 5% of the rocks preserved are older than 3 Ga. In addition, there is no recognizable mantle lithosphere from before 3 Ga. We infer that there was lithosphere before 3 Ga and that ∼3 Ga marks the stabilization of blocks of continental lithosphere that have since survived. This was linked to plate tectonics emerging as the dominant tectonic regime in response to thermal cooling, the development of a more rigid lithosphere, and the recycling of water, which may in turn have facilitated plate tectonics. A number of models, using different approaches, suggest that at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value. The continental crust before 3 Ga was on average more mafic than that generated subsequently, and this pre-3 Ga mafic new crust had fractionated Lu/Hf and Sm/Nd ratios as inferred for the sources of tonalite-trondhjemite-granodiorite and later granites. The more intermediate composition of new crust generated since 3 Ga is indicated by its higher Rb/Sr ratios. This change in composition was associated with an increase in crustal thickness, which resulted in more emergent crust available for weathering and erosion. This in turn led to an increase in the Sr isotope ratios of seawater and in the drawdown of CO2. Since 3 Ga, the preserved record of the continental crust is marked by global cycles of peaks and troughs of U-Pb crystallization ages, with the peaks of ages appearing to match periods of supercontinent assembly. There is increasing evidence that the peaks of ages represent enhanced preservation of magmatic rocks in periods leading up to and including continental collision in the assembly of supercontinents. These are times of increased crustal growth because more of the crust that is generated is retained within the crust. The rates of generation of continental crust and mantle lithosphere may have remained relatively constant at least since 3 Ga, yet the rates of destruction of continental crust have changed with time. Only relatively small volumes of rock are preserved from before 3 Ga, and so it remains difficult to establish which of these are representative of global processes and the extent to which the rock record before 3 Ga is distorted by particular biases
Earth's continental lithosphere through time
The record of the continental lithosphere is patchy and incomplete; no known rock is older than 4.02 Ga, less than 5% of the rocks preserved are older than 3 Ga, and there is no recognizable mantle lithosphere from before 3 Ga. We infer that there was lithosphere before 3 Ga, and that ~ 3 Ga marks the stabilization of blocks of continental lithosphere that have since survived. This was linked to plate tectonics emerging as the dominant tectonic regime in response to thermal cooling, the development of more rigid lithosphere, and the recycling of water that may in turn have facilitated plate tectonics. A number of models, using different approaches, suggest that at 3 Ga the volume of continental crust was ~70% of its present day volume, and that this may be a minimum value. The continental crust before 3 Ga was on average more mafic than that generated subsequently, and this pre-3 Ga mafic new crust had fractionated Lu/Hf and Sm/Nd ratios as inferred for the sources of tonalite-trondhjemite-granodiorite (TTG) and later granites. The more intermediate composition of crust generated since 3 Ga is indicated by its higher Rb/Sr ratios. This change in composition was associated with an increase in crustal thickness, which resulted in more crust being emergent and available for weathering and erosion. This in turn led to an increase in the Sr isotope ratios of sea water, and in the draw down of CO2. Since 3 Ga, the preserved record of the continental crust is marked by global cycles of peaks and troughs of U-Pb crystallization ages, with the peaks of ages appearing to match periods of supercontinent assembly. There is increasing evidence that the peaks of ages represent enhanced preservation of magmatic rocks in periods leading up to and including continental collision, in the assembly of supercontinents. These are times of increased crustal growth because more of the crust that is generated is retained within the crust. The rate of generation of continental crust and mantle lithosphere may have remained relatively constant at least since 3 Ga, yet the rates of destruction of continental crust have changed with time. Only relatively small volumes of rock are preserved from before 3 Ga, and so it remains difficult to establish which of these are representative of global processes, and the extent to which the rock record before 3 Ga is distorted by particular biases
Generation and preservation of continental crust in the Grenville Orogeny
Detrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of 'peaks' and 'troughs'. The peaks are interpreted to represent either periods of enhanced generation of granitic magma perhaps associated with mantle overturn and superplume events, or preferential preservation of continental crust during global collisional orogenesis. The close association of those peaks with the assembly of supercontinents implies a causal relationship between collisional orogenesis and the presence of zircon age peaks. Here these two end-member models (episodic periodicity of increased magmatism versus selective preservation during collisional orogenesis) are assessed using U-Pb, Hf, and O analysis of detrital zircons from sedimentary successions deposited during the ∼1.3-1.1 Ga accretionary, ∼1.1-0.9 Ga collisional, and <0.9 Ga extensional collapse phases of the Grenville orogenic cycle in Labrador and Scotland. The pre-collisional, accretionary stage provides a baseline of continental crust present prior to orogenesis and is dominated by Archean and Paleoproterozoic age peaks associated with pre-1300 Ma Laurentian geology. Strata deposited during the Grenville Orogeny display similar Archean and Paleoproterozoic detrital populations along with a series of broad muted peaks from ∼1500 to 1100 Ma. However, post-collisional sedimentary successions display a dominant age peak between 1085 and 985 Ma, similar to that observed in modern North American river sediments. Zircons within the post-orogenic sedimentary successions have progressively lower εHf and higher δ18O values from ∼1800 to ∼1200 Ma whereupon they have higher εHf and δ18O within the dominant 1085-985 Ma age peak. Furthermore, the Lu-Hf isotopic profile of the Grenville-related age peak is consistent with significant assimilation and contamination by older crustal material. The timing of this dominant age peak coincides with the peak of metamorphism and magmatism associated with the Grenville Orogeny, which is a typical collisional orogenic belt. The change from broad muted age peaks in the syn-orogenic strata to a single peak in the post-orogenic sedimentary successions and in the modern river sediments implies a significant shift in provenance following continental collision. This temporal change in provenance highlights that the source(s), from which detrital zircons within syn-orogenic strata were derived, was no longer available during the later stages of the accretionary and collisional stages of the orogenic cycle. This may reflect some combination of tectonic burial, erosion, or possibly recycling into the mantle by tectonic erosion of the source(s). During continental collision, the incorporated continental crust is isolated from crustal recycling processes operative at subduction margins. This tectonic isolation combined with sedimentary recycling likely controls the presence of the isotopic signature associated with the Grenville Orogeny in the modern Mississippi and Appalachian river sediments. These results imply that zircon age peaks, which developed in conjunction with supercontinents, are the product of selective crustal preservation resulting from collisional orogenesis.</p
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Independent Membrane Binding Properties of the Caspase Generated Fragments of the Beaded Filament Structural Protein 1 (BFSP1) Involves an Amphipathic Helix.
BACKGROUND: BFSP1 (beaded filament structural protein 1) is a plasma membrane, Aquaporin 0 (AQP0/MIP)-associated intermediate filament protein expressed in the eye lens. BFSP1 is myristoylated, a post-translation modification that requires caspase cleavage at D433. Bioinformatic analyses suggested that the sequences 434-452 were α-helical and amphipathic. METHODS AND RESULTS: By CD spectroscopy, we show that the addition of trifluoroethanol induced a switch from an intrinsically disordered to a more α-helical conformation for the residues 434-467. Recombinantly produced BFSP1 fragments containing this amphipathic helix bind to lens lipid bilayers as determined by surface plasmon resonance (SPR). Lastly, we demonstrate by transient transfection of non-lens MCF7 cells that these same BFSP1 C-terminal sequences localise to plasma membranes and to cytoplasmic vesicles. These can be co-labelled with the vital dye, lysotracker, but other cell compartments, such as the nuclear and mitochondrial membranes, were negative. The N-terminal myristoylation of the amphipathic helix appeared not to change either the lipid affinity or membrane localisation of the BFSP1 polypeptides or fragments we assessed by SPR and transient transfection, but it did appear to enhance its helical content. CONCLUSIONS: These data support the conclusion that C-terminal sequences of human BFSP1 distal to the caspase site at G433 have independent membrane binding properties via an adjacent amphipathic helix
Independent Membrane Binding Properties of the Caspase Generated Fragments of the Beaded Filament Structural Protein 1 (BFSP1) Involves an Amphipathic Helix
Background: BFSP1 (beaded filament structural protein 1) is a plasma membrane, Aqua- 21 porin 0 (AQP0/MIP)-associated intermediate filament protein expressed in the eye lens. BFSP1 is 22 myristoylated, a post-translation modification that requires caspase cleavage at D433. Bioinformatic 23 analyses suggested that the sequences 434-452 were a-helical and amphipathic. Methods and Re- 24 sults: By CD spectroscopy, we show that the addition of trifluoroethanol induced a switch from an 25 intrinsically disordered to a more a-helical conformation for the residues 434-467. Recombinantly 26 produced BFSP1 fragments containing this amphipathic helix bind to lens lipid bilayers as deter- 27 mined by surface plasmon resonance (SPR). Lastly, we demonstrate by transient transfection of non- 28 lens MCF7 cells that these same BFSP1 C-terminal sequences localise to plasma membranes and to 29 cytoplasmic vesicles. These can be co-labelled with the vital dye, lysotracker, but other cell compart- 30 ments such as the nuclear and mitochondrial membranes were negative. The N-terminal myristoy- 31 lation of the amphipathic helix appeared not to change either the lipid affinity or membrane locali- 32 sation of the BFSP1 polypeptides or fragments we assessed by SPR and transient transfection, but it 33 did appear to enhance its helical content. Conclusions: These data support the conclusion that C- 34 terminal sequences of human BFSP1 distal to the caspase site at G433 have independent membrane 35 binding properties via an adjacent amphipathic helix
An amphipathic helix facilitates the membrane binding properties of BFSP1 and its caspase-generated C-terminal domain
Background: BFSP1 (beaded filament structural protein 1) is a plasma membrane, Aqua- 21 porin 0 (AQP0/MIP)-associated intermediate filament protein expressed in the eye lens. BFSP1 is 22 myristoylated, a post-translation modification that requires caspase cleavage at D433. Bioinformatic 23 analyses suggested that the sequences 434-452 were a-helical and amphipathic. Methods and Re- 24 sults: By CD spectroscopy, we show that the addition of trifluoroethanol induced a switch from an 25 intrinsically disordered to a more a-helical conformation for the residues 434-467. Recombinantly 26 produced BFSP1 fragments containing this amphipathic helix bind to lens lipid bilayers as deter- 27 mined by surface plasmon resonance (SPR). Lastly, we demonstrate by transient transfection of non- 28 lens MCF7 cells that these same BFSP1 C-terminal sequences localise to plasma membranes and to 29 cytoplasmic vesicles. These can be co-labelled with the vital dye, lysotracker, but other cell compart- 30 ments such as the nuclear and mitochondrial membranes were negative. The N-terminal myristoy- 31 lation of the amphipathic helix appeared not to change either the lipid affinity or membrane locali- 32 sation of the BFSP1 polypeptides or fragments we assessed by SPR and transient transfection, but it 33 did appear to enhance its helical content. Conclusions: These data support the conclusion that C- 34 terminal sequences of human BFSP1 distal to the caspase site at G433 have independent membrane 35 binding properties via an adjacent amphipathic helix