The mosquito genome--a breakthrough for public health

The Anopheles gambiae genome sequence will accelerate identification of new insect vector target genes leading to improved strategies for malaria control.     

The role of microorganisms in elemental mercury formation in natural waters

Gas evasion of elemental Hg (Hg°) from the open ocean plays a prominent role in the global mercury cycle. Elemental Hg is formed primarily by reduction of ionic Hg in the mixed layer of aquatic systems. By culturing phytoplankton in defined media, and by incubating natural seawater and freshwater samples, we have demonstrated that Hg° is produced by microorganisms, with formation rates (0.5 to 10% d^?1) similar to those estimated from mass balance studies. Our results also suggest that <3μm microorganisms are the primary Hg reducers in natural waters. Eucaryotic phytoplankton are capable of reducing ionic Hg to Hg° but the rate of reduction is insufficient to account for the observed reduction rates found in incubated field samples. Bacteria are thus the more likely Hg reducers. In seawater, cyanobacteria such asSynecococcus may account for much of the mercury reduction, while in the eutrophic, polluted Upper Mystic Lake north of Boston other procaryotic microorganisms are contributing to the overall Hg reductive capacity of the medium. By reducing ionic Hg, microorganisms play a pivotal role in the aquatic biogeochemistry of Hg, not only by enabling evasion to the atmosphere, but by directly decreasing the amount of ionic Hg available for methylation.     

Bioaccumulation of mercury and methylmercury

The factors controlling the accumulation of mercury in fish are poorly understood. The oft invoked lipid solubility of MMHg is an inadequate explanation because inorganic Hg complexes, which are not bioaccumulated, are as lipid soluble as their MMHg analogs and, unlike other hydrophobic compounds, MMHg in fish resides in protein rather than fat tissue. We show that passive uptake of the lipophilic complexes (primarily HgCl₂ and CH₃HgCl) results in high concentrations of both inorganic and MMHg in phytoplankton. However, differences in partitioning within phytoplankton cells between inorganic mercury — which is principally membrane bound — and MMHg — which accumulates in the cytoplasm — lead to a greater assimilation of MMHg during Zooplankton grazing. Most of the discrimination between inorganic and MMHg thus occurs during trophic transfer while the major enrichment factor is between water and phytoplankton. As a result, MMHg concentrations in fish are ultimately determined by water chemistry which controls MMHg speciation and uptake at the base of the food chain.     

Wheat gluten phenolic acids: occurrence and fate upon mixing

Ferulic acid (FA, 4.9-17.7 microg/100 mg), sinapic acid (SA, 1.4-3.5 microg/100 mg), and traces of p-coumaric acid and vanillic acid were detected after saponification of six wheat glutens from industrial and pilot-scale origins. FA and SA occurred mostly as soluble-bound and insoluble-bound forms according to their extractability by acetone/methanol/water (7:7:6, v/v/v). The major part of FA (50-95%) was found in the unextractable fraction, whereas SA was mostly extractable (64-85%). The carbohydrate contents of the glutens were determined also after acid hydrolysis. The highest levels of glucose, arabinoxylan, and FA were obtained from the unextractable fractions of the pilot-scale extracted glutens, probably in relation with a lower efficiency of washing during extraction compared to industrial processes. On the other hand, SA compounds were in similar concentrations in all samples, suggesting their involvement in specific interactions during gluten protein agglomeration. Saponification of the soluble-bound phenolic acids released mainly glucose, whereas a beta-glucosidase treatment had no effect. FA and SA extractability, especially that of soluble-bound ones, decreased strongly in overmixed gluten/water doughs. These low molecular weight conjugates of phenolic acids could be involved in the dough breakdown phenomenon.     

A seeding experiment of juvenile great scallops (Pecten maximus (L.)) off the Island of Jersey.

In 1995, landings of Great scallops, Pecten maximus(L.) increased dramatically in Jersey from around one tonne in the previousyear, to 66 tonnes and this continues to rise. This was caused by theintroduction of scallop diving permits and diversification of the fishingfleet.Due to this increase in effort it was decided that the feasibility of ranchingone-year-old juvenile scallops should be investigated. 100,000 scallops werepurchased from Ireland and seeded in specifically selected coastal sites. Thescallops grew from 22.8 mm shell length and 1.17 grams to 57.6mm and 23.2 grams in the first six months after seeding, and to93.3 mm and 88.9 grams during the subsequent 12 months. Growthrateslowed considerably during winter months. Given these growth rates the scallopswill reach market size in three years from settlement, less than the 4, 5 and 6years taken in Guernsey, the Eastern Channel and the offshore Irish Searespectively. Although growth rates are not unique and are comparable withotherinshore sites in the UK, they are significant for scallop farming in Jerseywaters. Mortality following re-seeding and predation rates by crab and starfishappears to be lower than reported by other workers. However this has not yetbeenquantified.     

Estimating aboveground biomass in forest and oil palm plantation in Sabah, Malaysian Borneo using ALOS PALSAR data

Conversion of tropical forests to oil palm plantations in Malaysia and Indonesia has resulted in large-scale environmental degradation, loss of biodiversity and significant carbon emissions. For both countries to participate in the United Nation’s REDD (Reduced Emission from Deforestation and Degradation) mechanism, assessment of forest carbon stocks, including the estimated loss in carbon from conversion to plantation, is needed. In this study, we use a combination of field and remote sensing data to quantify both the magnitude and the geographical distribution of carbon stock in forests and timber plantations, in Sabah, Malaysia, which has been the site of significant expansion of oil palm cultivation over the last two decades. Forest structure data from 129 ha of research and inventory plots were used at different spatial scales to discriminate forest biomass across degradation levels. Field data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) imagery to both discriminate oil palm plantation from forest stands, with an accuracy of 97.0% (κ = 0.64) and predict AGB using regression analysis of HV-polarized PALSAR data (R² = 0.63, p < .001). Direct estimation of AGB from simple regression models was sensitive to both environmental conditions and forest structure. Precipitation effect on the backscatter data changed the HV prediction of AGB significantly (R² = 0.21, p < .001), and scattering from large leaves of mature palm trees significantly impeded the use of a single HV-based model for predicting AGB in palm oil plantations. Multi-temporal SAR data and algorithms based on forest types are suggested to improve the ability of a sensor similar to ALOS PALSAR for accurately mapping and monitoring forest biomass, now that the ALOS PALSAR sensor is no longer operational.     

一个定量植物吸收土壤重金属的原理模型

本文根据土壤重金属向植物体转移的机理，提出了一个土壤－植物系统中元素解吸、迁移、吸收的联合数学模型，推导出植物吸收量与土壤溶液浓度、缓冲能力系数、扩散系数、根系总长度、平均半径、植物蒸腾量、生长时间等参数的定量关系式。用该模型计算的植物吸镉量与盆栽黑麦草实际吸镉量之间具有很高的相关性和较好的准确度。     

Predicting available phosphate ions from physical–chemical soil properties in acidic sandy soils under pine forests

Purpose  

For economic and environmental reasons, and for biomass production, appropriate concepts and diagnostic systems based on relevant processes are required to assess the phosphorus (P) supply capacity of the soils in the long term and to adapt P fertilization accordingly in forests. The amount of available phosphate ions (iP) can be quantified using an isotopic dilution procedure. However, this method is difficult to apply since it requires the use of radioactivity (³²P or ³³P). Our objective was thus to build pedotransfer functions for the prediction of available iP from physical–chemical soil properties.