Analysis of shade and temperature effects on assimilate partitioning in the everbearing strawberry 'Everest' as the basis for optimised long-season fruit production

Growth patterns and cropping were evaluated over the season for the everbearing strawberry 'Everest' at a range of temperatures (15-27degreesC) in two light environments (ambient and 50% shade). The highest yield was recorded for unshaded plants grown at 23degreesC, but the optimum temperature for vegetative growth was 15degreesC. With increasing temperature fruit number increased, but fruit weight decreased. Fruit weight was also significantly reduced by shade, and although 'Everest' showed a degree of shade tolerance in vegetative growth, yield was consistently reduced by shade. Shade also reduced the number of crowns developed by the plants over the course of the season, emphasising that crown number was ultimately the limiting factor for yield potential. We conclude that, in contrast to Junebearers which partition more assimilates to fruit at temperatures around 15degreesC (Le Miere et al., 1998), optimised cropping in the everbearer 'Everest' is achieved at the significantly higher temperature of 23degreesC. These findings have significance for commercial production, in which protection tends to reduce light levels but increase average temperature throughout the season.

Bidentates versus monodentates in asymmetric hydrogenation catalysis: synergic effects on rate and allosteric effects on enantioselectivity

C-1-Symmetric phosphino/phosphonite ligands are prepared by the reactions of Ph2P(CH2)(2)P(NMe2)(2) with (S)-1,11'-bi-2-naphthol (to give L-A) or (S)-10,10'-bi-9-phenanthrol (to give L-B). Racemic 10,10'-bi-9-phenanthrol is synthesized in three steps from phenanthrene in 44% overall yield. The complexes [PdCl2(L-A,L-B)] (1a,b), [PtCl2(L-A,L-B)] (2a,b), [Rh(cod)(L-A,L-B)]BF4 (3a,b) and [Rh(L-A,L-B)(2)]BF4 (4a,b) are reported and the crystal structure of la has been determined. A P-31 NMR study shows that M, a 1:1 mixture of the monodentates, PMePh2 and methyl monophosphonite L-1a (based on (S)-1,11'-bi-2-naphthol), reacts with 1 equiv of [Rh(cod)(2)]BF4 to give the heteroligand complex [Rh(cod)(PMePh2)(L-1a)]BF4 (5) and homoligand complexes [Rh(cod)(PMePh2)(2)]BF4 (6) and [Rh(cod)(L-1a)(2)]BF4 (7) in the ratio 2:1:1. The same mixture of 5-7 is obtained upon mixing the isolated homoligand complexes 6 and 7 although the equilibrium is only established rapidly in the presence of an excess of PMePh2. The predominant species 5 is a monodentate ligand complex analogue of the chelate 3a. When the mixture of 5-7 is exposed to 5 atm H-2 for 1 h (the conditions used for catalyst preactivation in the asymmetric hydrogenation studies), the products are identified as the solvento species [Rh(PMePh2)(L-1a)(S)(2)]BF4 (5'), [Rh(S)(2)(PMePh2)(2)]BF4 (6') and [Rh(S)(2)(L-1a)(2)]BF4 (7') and are formed in the same 2:1:1 ratio. The reaction of M with 0.5 equiv of [Rh(cod)(2)]BF4 gives exclusively the heteroligand complex cis-[Rh(PMePh2)(2)(L-1a)(2)]BF4 (8), an analogue of 4a. The asymmetric hydrogenation of dehydroamino acid derivatives catalyzed by 3a,b is reported, and the enantioselectivities are compared with those obtained with (a) chelate catalysts derived from analogous diphosphonite ligands L-2a and L-2b, (b) catalysts based on methyl monophosphonites L-1a and L-1b, and (c) catalysts derived from mixture M. For the cinnamate and acrylate substrates studied, the catalysts derived from the phosphino/phosphonite bidentates L-A,L-B generally give superior enantioselectivities to the analogous diphosphonites L-2a and L-2b; these results are rationalized in terms of delta/lambda-chelate conformations and allosteric effects of the substrates. The rate of hydrogenation of acrylate substrate A with heterochelate 3a is significantly faster than with the homochelate analogues [Rh(L-2a)(cod)]BF4 and [Rh(dppe)(cod)]BF4. A synergic effect on the rate is also observed with the monodentate analogues: the rate of hydrogenation with the mixture containing predominantly heteroligand complex 5 is faster than with the monophosphine complex 6 or monophosphonite complex 7. Thus the hydrogenation catalysis carried out with M and [Rh(cod)(2)]BF4 is controlled by the dominant and most efficient heteroligand complex 5. In this study, the heterodiphos chelate 3a is shown to be more efficient and gives the opposite sense of optical induction t the heteromonophos analogue

Polymorphisms in the apolipoprotein L1 gene and their effects on blood lipid and glucose levels in middle age males

Apolipoprotein L1 in plasma is associated with high- density lipoprotein. Novel APOL1 polymorphisms are investigated along with the association of two common haplotypes (Lys166Glu, Ile244Met, Lys271Arg) with circulating lipid and glucose levels. Although the amino acid substitutions occur in the amphipathic alpha helices region involved in lipid binding, these substitutions were found not to independently account for variability in circulating lipid and glucose levels in 149 middle age males.

Established and emerging prebiotics and their effects on the gut microflora

The use of probiotics combined with prebiotics (synbiotics) has been proved to be more and more interesting in the market of functional foods. The use of probiotics alone has a long history whereas the concept of prebiotics is rather new, introduced by Gibson & Roberfroid(1). Efficient prebiotics are considered the compounds that are not digested and selectively promote the growth of beneficial microorganisms (such as lactobacilli and bifidobacteria) in the colon. Some established prebiotics that are currently used in the European market are fructooligosaccharides (FOS), galactooligosaccharides (GOS) and inulin. However, there are more compounds considered as "emerging prebiotics" which have not been established yet, but there is a need of further investigation on them. Some of them are oligomers of soya & xylan, isomalto-oligosaccharides (IMO), polydextrose and possibly some oligosaccharides in honey. There is still an incomplete picture of their fermentation properties but according to the studies performed till now, it is quite possible that these molecules might have the same or more desirable properties than the established ones. In this review, the effects of the established and emerging prebiotics on the gut microflora are presented, based on in vitro and in vivo studies (healthy volunteers).

Inulin and oligofructose: effects on lipid metabolism from human studies

Although convincing lipid-lowering effects of the fructo-oligosaccharide, inulin, have been demonstrated in animals, attempts to reproduce similar effects in man have produced conflicting findings. This may be because of the much lower doses which can be used due to the adverse gastrointestinal symptoms exhibited by most subjects consuming in excess of 15 g/d. There are nine studies reported in the literature which have investigated the response of blood lipids (usually total and LDL-cholesterol and triacylglycerol) to inulin or oligofructose supplementation in human volunteers. Three have observed no effects of inulin or oligofructose on blood levels of cholesterol or triacylglycerol, three have shown significant reductions in triacylglycerol, whilst four have shown modest reductions in total and LDL-cholesterol. Studies have been conducted in both normo- and moderately hyperlipidaemic subjects. Differences in study outcomes do not appear to be due to differences in the type or dose of oligosaccharides used nor the duration of the studies. Because animal studies have identified inhibition of hepatic fatty acid synthesis as the major site of action for the triacylglycerol lowering effects of inulin and oligofructose, and because this pathway is relatively inactive in man unless a high carbohydrate diet is fed, variability in response may be a reflection of differences in background diet or the experimental foods used.

Substituent and counterion effects on the formation of p-dimer dications of end-capped heptathienoacenes

We have investigated the impact of the functionalization and the chemical nature of counterions on the p-dimer dications formation in two end-capped heptathienoacenes. Radical cations of an a-substituted heptathienoacene with triisopropylsilyl groups do not p-dimerize, while those of an a,b-substituted heptathienoacene with four n-decyl side chains show a high propensity toward p-dimerization, increased by PF6 ÿ counterions.

Legume type and temperature effects on the toxicity of insecticide to the genus Callosobruchus (Coleoptera: Bruchidae)

Three bruchid pest species, Callosobruchus maculatus, Callosobruchus chinensis and Callosobruchus rhodesianus, were studied for their response to insecticide toxicity taking into account the separate and interactive effects of temperature and pre-adult food. The food types used were cowpea (Vigna unguiculata) and mungbean (Vigna radiata). Callosobruchus maculatus was the most tolerant to malathion and the least affected by temperature change while C. rhodesianus was the least tolerant. Over a 4 C range (23, 25, 27 C), there was generally a significant impact of temperature on the tolerance of the three species to the insecticide. The food type on which the insects developed influenced considerably the degree of insecticide tolerance. Callosobruchus maculatus and C. chinensis populations reared onmungbean had higher tolerance to malathion than their counterparts reared on cowpea, but the opposite was observed in C. rhodesianus populations. The food influence in this study suggested an ancestral cause or fitness cost depending on the species. The interaction of food-by-temperature had no significant effect on malathion toxicity to this genus. Correlation analysis showed C. chinensis to be relatively less sensitive to insecticide concentration over the range studied compared with the other two species.

Market power and its effects on equilibrium in the food system

When food processors have conjectures about rival firms' responses, their profit functions can be used to estimate the degree of market power in the food system. The effects of this power are investigated analytically and through applying the results to the U.S. pork sector

Normal mode Rossby waves and their effects on chemical composition in the late summer stratosphere

During past MANTRA campaigns, ground-based measurements of several long-lived chemical species have revealed quasi-periodic fluctuations on time scales of several days. These fluctuations could confound efforts to detect long-term trends from MANTRA, and need to be understood and accounted for. Using the Canadian Middle Atmosphere Model, we investigate the role of dynamical variability in the late summer stratosphere due to normal mode Rossby waves and the impact of this variability on fluctuations in chemical species. Zonal wavenumber 1, westward travelling waves are considered with average periods of 5, 10 and 16 days. Time-lagged correlations between the temperature and nitrous oxide, methane and ozone fields are calculated in order to assess the possible impact of these waves on the chemical species. Using Fourier-wavelet decomposition and correlating the fluctuations between the temperature and chemical fields, we determine that variations in the chemical species are well-correlated with the 5- and 10-day waves between 30 and 60 km, although the nature of the correlations depend strongly on altitude. Interannual variability of the waves is also examined.

A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems

Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local-scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high-quality habitats; bee richness on conventional fields with low diversity benefited most from high-quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high-quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.

Comparison of pollinators and natural enemies: a meta-analysis of landscape and local effects on abundance and richness in crops

To manage agroecosystems for multiple ecosystem services, we need to know whether the management of one service has positive, negative, or no effects on other services. We do not yet have data on the interactions between pollination and pest-control services. However, we do have data on the distributions of pollinators and natural enemies in agroecosystems. Therefore, we compared these two groups of ecosystem service providers, to see if the management of farms and agricultural landscapes might have similar effects on the abundance and richness of both. In a meta-analysis, we compared 46 studies that sampled bees, predatory beetles, parasitic wasps, and spiders in fields, orchards, or vineyards of food crops. These studies used the proximity or proportion of non-crop or natural habitats in the landscapes surrounding these crops (a measure of landscape complexity), or the proximity or diversity of non-crop plants in the margins of these crops (a measure of local complexity), to explain the abundance or richness of these beneficial arthropods. Compositional complexity at both landscape and local scales had positive effects on both pollinators and natural enemies, but different effects on different taxa. Effects on bees and spiders were significantly positive, but effects on parasitoids and predatory beetles (mostly Carabidae and Staphylinidae) were inconclusive. Landscape complexity had significantly stronger effects on bees than it did on predatory beetles and significantly stronger effects in non-woody rather than in woody crops. Effects on richness were significantly stronger than effects on abundance, but possibly only for spiders. This abundance-richness difference might be caused by differences between generalists and specialists, or between arthropods that depend on non-crop habitats (ecotone species and dispersers) and those that do not (cultural species). We call this the ‘specialist-generalist’ or ‘cultural difference’ mechanism. If complexity has stronger effects on richness than abundance, it might have stronger effects on the stability than the magnitude of these arthropod-mediated ecosystem services. We conclude that some pollinators and natural enemies seem to have compatible responses to complexity, and it might be possible to manage agroecosystems for the benefit of both. However, too few studies have compared the two, and so we cannot yet conclude that there are no negative interactions between pollinators and natural enemies, and no trade-offs between pollination and pest-control services. Therefore, we suggest a framework for future research to bridge these gaps in our knowledge.

Detection of solar dimming and brightening effects on Northern Hemisphere river flow

Anthropogenic aerosols in the atmosphere have the potential to affect regional-scale land hydrology through solar dimming. Increased aerosol loading may have reduced historical surface evaporation over some locations, but the magnitude and extent of this effect is uncertain. Any reduction in evaporation due to historical solar dimming may have resulted in an increase in river flow. Here we formally detect and quantify the historical effect of changing aerosol concentrations, via solar radiation, on observed river flow over the heavily industrialized, northern extra-tropics. We use a state-of-the-art estimate of twentieth century surface meteorology as input data for a detailed land surface model, and show that the simulations capture the observed strong inter-annual variability in runoff in response to climatic fluctuations. Using statistical techniques, we identify a detectable aerosol signal in the observed river flow both over the combined region, and over individual river basins in Europe and North America. We estimate that solar dimming due to rising aerosol concentrations in the atmosphere around 1980 led to an increase in river runoff by up to 25% in the most heavily polluted regions in Europe. We propose that, conversely, these regions may experience reduced freshwater availability in the future, as air quality improvements are set to lower aerosol loading and solar dimming.