Revisiting carbon flux through the ocean's twilight zone

The oceanic biological pump drives sequestration of carbon dioxide in the deep sea via sinking particles. Rapid biological consumption and remineralization of carbon in the "twilight zone" (depths between the euphotic zone and 1000 meters) reduce the efficiency of sequestration. By using neutrally buoyant sediment traps to sample this chronically understudied realm, we measured a transfer efficiency of sinking particulate organic carbon between 150 and 500 meters of 20 and 50% at two contrasting sites. This large variability in transfer efficiency is poorly represented in biogeochemical models. If applied globally, this is equivalent to a difference in carbon sequestration of more than 3 petagrams of carbon per year.     

A 5-micron-bright spot on Titan: evidence for surface diversity

Observations from the Cassini Visual and Infrared Mapping Spectrometer show an anomalously bright spot on Titan located at 80 degrees W and 20 degrees S. This area is bright in reflected light at all observed wavelengths, but is most noticeable at 5 microns. The spot is associated with a surface albedo feature identified in images taken by the Cassini Imaging Science Subsystem. We discuss various hypotheses about the source of the spot, reaching the conclusion that the spot is probably due to variation in surface composition, perhaps associated with recent geophysical phenomena.     

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep

Background: The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short(2-wk) and long(8-wk) durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations. We also used direct fetal insulin infusions(1-wk hyperinsulinemic-isoglycemic clamp) to determine the relative importance of fetal glucose and insulin for regulating non-glucose carbohydrates.Results: A maternal insulin infusion resulted in lower maternal(50%, P < 0.01) and fetal(35-45%, P < 0.01) mannose concentrations, which were highly correlated(r2= 0.69, P < 0.01). A fetal insulin infusion resulted in a 50% reduction of fetal mannose(P < 0.05). Neither maternal nor fetal plasma inositol changed with exogenous insulin infusions.Additionally, maternal insulin infusion resulted in lower fetal sorbitol and fructose(P < 0.01).Conclusions: Chronically decreased glucose supply to the fetus as well as fetal hyperinsulinemia both reduce fetal non-glucose carbohydrates. Given the role of these carbohydrates in protein glycosylation and lipid production, more research on their metabolism in pregnancies complicated by abnormal glucose metabolism is clearly warranted.     

Needs-based decision-making for cotton problems in Africa: A response to Hillocks

Abstract

This Forum contribution forms a response to the thoughtful article on the role of Bt cotton for African smallholders by Rory Hillocks in International Journal of Pest Management 51(2):131–141. We urge a more nuanced approach to consideration of pesticide-related and other technical issues in the conventional cotton sector, including recent estimates of external costs to health from current patterns of pesticide use, even at the low application levels in volume/area terms reported from Africa. We examine economic and institutional aspects of cotton production and the debates centred upon the potential of Bt cotton for resource-poor farmers in developing countries. Based on research and project experience over the last decade, we discuss the role of organic cotton and the benefits it provides for African men and women smallholders, and conclude with a summary of the potential for expansion and policy, research and development needs.     

Erarbeitung eines Testverfahrens zur Bestimmung der Protektiv- und Kurativleistung von Fungiziden bei der Bek?mpfung des Erregers der Stemphylium-Laubkrankheit Stemphylium botryosum in der Spargelkultur (Asparagus officinalis L.)

The foilage of Asparagus officinalis L. has a large contact surface for different leaf diseases, which can lead to profits cuts, especially by the causal pathogen of Stemphylium leaf spot, Stemphylium botryosum. The maintaining healthy of the foliage is an important precondition to achieve an optimal harvest in the following year. Therefore, it is necessary to describe the efficacy of currently approved plant protection products against S. botryosum in order to optimize the fungicide applications. In the context of greenhouse trials with asparagus seedlings a method should be developed to evaluate the preventive and curative efficacy of fungicides. At the beginning, stable, repeatable and homogeneous infections of S. botryosum needed to be achieved. Ad hoc the factors plant age (weeks after sowing date), inoculum (density of conidia per ml and concentration of malt), infection conditions (period of high relative humidity) and day of rating, as well as their influence on the occurrence of the symptoms, were investigated. With the exception of the factor plant age, the other factors had a significant effect on the infection. For the trials to evaluate the efficacy of fungicides, the analysed factors were defined. The age of the seedlings was six weeks after sowing, the inoculum was composed of 1,00?×?10⁵ conidia per ml combined with an 0,5% malt concentration, as infection condition the ??tunnel system?? with periodically high relative humidity was chosen. 13 days past infection was the optimal day of rating. To apply the seedlings with the fungicides, the registered application rate was reduced to 1/5. The trials to evaluate fungicides were conducted with the fungicides Signum^®, Rovral^® WG and two different testing agencies. At four consecutive application days, the plants were covered with fungicides. In the following, the infestation degree of stems in percent was evaluated. Additionally, the used S. botryosum-Isolates were biomolecularly investigated and the QoI- and SDHI resistance state determined.