Interferon induction in human lymphocytes by complexes of vinyl copolymers with polynucleotides

Analogues of the dsRNA poly(I).poly(C), namely double-stranded like complexes of poly(I) or poly(C), respectively, with corresponding vinyl nucleobases copolymerized with various vinyl compounds are highly effective interferon inducers in human lymphocyte cultures. Like poly(I).poly(C) they stimulate the liberation of an inhibitor(s) of interferon activity and, moreover, display mitogenic effect. With respect to the extent of these effects the various inducers differ considerably.     

Diversity of the plasma membrane properties of transplantable hamster melanomas with regard to the expression of P-glycoprotein.

A comparison of the expression of P-glycoprotein (Pgp) was performed in two forms of hamster transplantable melanomas of common origin, but differing in growth rates and levels of differentiation. The expression of P-glycoprotein in plasma membranes of these two forms of melanomas was estimated by the western blot analysis and the transport activity of the Pgp compared by flow cytometry. It was observed that a spontaneous alteration in the original melanotic melanoma leading to a formation of the amelanotic form characterized by higher growth rate, greater anaplasticity and leading to the animals' death after a shorter time from inoculation, was accompanied by a decrease in the Pgp expression and activity, due to simultaneous appearance of a small population of amelanotic cells with high Pgp expression and activity, and disappearance of this activity from the major population. It is possible, that the activity of Pgp in the melanoma cell membranes reflects the degree of cell differentiation.     

L2′ loop is critical for caspase‐7 active site formation

The active sites of caspases are composed of four mobile loops. A loop (L2) from one half of the dimer interacts with a loop (L2′) from the other half of the dimer to bind substrate. In an inactive form, the two L2′ loops form a cross‐dimer hydrogen‐bond network over the dimer interface. Although the L2′ loop has been implicated as playing a central role in the formation of the active‐site loop bundle, its precise role in catalysis has not been shown. A detailed understanding of the active and inactive conformations is essential to control the caspase function. We have interrogated the contributions of the residues in the L2′ loop to catalytic function and enzyme stability. In wild‐type and all mutants, active‐site binding results in substantial stabilization of the complex. One mutation, P214A, is significantly destabilized in the ligand‐free conformation, but is as stable as wild type when bound to substrate, indicating that caspase‐7 rests in different conformations in the absence and presence of substrate. Residues K212 and I213 in the L2′ loop are shown to be essential for substrate‐binding and thus proper catalytic function of the caspase. In the crystal structure of I213A, the void created by side‐chain deletion is compensated for by rearrangement of tyrosine 211 to fill the void, suggesting that the requirements of substrate‐binding are sufficiently strong to induce the active conformation. Thus, although the L2′ loop makes no direct contacts with substrate, it is essential for buttressing the substrate‐binding groove and is central to native catalytic efficiency.     

Modification of Emission Properties of ZnO Layers due to Plasmonic Near-Field Coupling to Ag Nanoislands

A simple fabrication method of silver (Ag) nanoislands on ZnO films is presented. Continuous wave and time-resolved photoluminescence and transmission are employed to investigate modifications of visible and UV emissions of ZnO brought about by coupling to localized surface plasmons residing on Ag nanoislands. The size of the nanoislands, determining their absorption and scattering efficiencies, is found to be an important factor governing plasmonic modification of optical response of ZnO films. The presence of the Ag nanoislands of appropriate dimensions causes a strong (threefold) increase in emission intensity and up to 1.5 times faster recombination. The experimental results are successfully described by model calculations within the Mie theory.     

Wild Foods: Safety Net or Poverty Trap? A South African Case Study

Wild foods contribute towards the food security of an estimated one billion people. In light of expectations of the contribution of wild foods to sustainable and climate-resilient livelihoods and widespread evidence of their consumption, their contribution to households’ diets requires a more nuanced understanding, specifically with respect to their safety net function during food shortages. Data were collected from two villages in Venda, South Africa, selected due to differences in mean annual precipitation. Semi-structured interviews were administered to 170 households and a Participatory Rural Appraisal was conducted to assess the influence of multiple variables, including household characteristics and site, on wild food use. Household archetypes were defined based on the frequency of consumption in response to increasing food scarcity. Our findings suggest limitations to the safety net function of wild foods including seasonal fluctuations in availability and decreased availability during extreme events, with dependent households decreasing their consumption frequency in response to food scarcity. Given this potential poverty trap, further research is required, particularly in terms of when the safety net function of wild foods may be weak or detrimental to the livelihoods of the vulnerable.     

Effect of temperature on seed production in the invasive grass Glyceria maxima (Hartm.) Holmb. (Poaceae) in South Africa

Temperature is one of the main factors that determine sexual reproduction in terrestrial and emergent aquatic plant species. The effect of temperature on sexual reproduction and seed production of Glyceria maxima (Hartm.) Holmb. in the southern hemisphere is unknown. Glyceria maxima collections in February 2010 at three isolated infestations in KwaZulu-Natal failed to yield a single seed, only empty panicles. Laboratory experiments showed that vernalisation had no consistent effect on seed production. Field- and laboratory-grown plants produced seeds in the 2010/2011 season, because of having sufficient time at optimum temperatures required for seed production (1 491 and 1 585 hours, respectively), compared to a shorter period (1 352 hours) of suitable temperatures during the 2009/2010 growing season. An inadequate period of optimum temperatures (15–25°C) during seed production resulted in the lack of seeds in the field in the 2009/2010 growing season. This study showed that temperature and duration of exposure thereto during the seed-production period play vital roles in G. maxima sexual reproduction.     

Dispersal of adult European corn borer (Lepidoptera: Crambidae) within and proximal to irrigated and non-irrigated corn.

The European corn borer, Ostrinia nubilalis (Hübner), causes economic damage to corn, Zea mays L., throughout the Corn Belt. Because this insect has become the primary target of Bacillus thuringiensis Berliner (Bt) transgenic corn, current efforts addressing the management of O. nubilalis resistance to Bt corn require information on adult European corn borer dispersal and factors affecting its dispersal. In 1998 we conducted mark-release-recapture, release-recapture, and caged-mating studies to directly measure and compare local dispersal patterns of O. nubilalis adults within and proximal to irrigated and non-irrigated cornfields. Releases of marked adults were made corresponding to the first and second flight of O. nubilalis in eastern Nebraska. Adult dispersal was significantly different between irrigated and non-irrigated cornfields. Released adults tended to remain in and near irrigated cornfields, but dispersed out of and away from non-irrigated cornfields. When released at the edge of the cornfield, neither male nor unmated female O. nubilalis displayed an initial tendency to move out of irrigated corn and into the mixed smooth bromegrass (Bromus inermis Leyss) and broadleaf-weed field edge. Mating efficiency in a late-season cornfield was not significantly different than in dense foxtail (Setaria spp.). Generally, we found that adult O. nubilalis dispersal may vary depending on variables such as action-site availability and agronomic practices and their interaction with O. nubilalis life history.