New polymorphic DNA marker close to the fragile site FRAXA

DNA from a human-hamster hybrid cell line, 908-K1B17, containing a small terminal portion of the long arm of the human X chromosome as well as the pericentric region of 19q was used as starting material for the isolation of an X-chromosome-specific DNA segment, RN1 (DXS369), which identifies a XmnI RFLP. Linkage analysis in fragile X families resulted in a maximum lod score of 15.3 at a recombination fraction of 0.05 between RN1 and fra(X). Analysis of recombinations around the fra(X) and distal to DXS105. Analysis of the marker content of hybrid cell line 908K1B17 suggests the localization of RN1 between DXS98 and fra(X). Heterozygosity of DXS369 is approximately 50%, which extends the diagnostic potential of RFLP analysis in fragile X families significantly.     

Beneficial and deleterious effects of HCN-producing pseudomonads on rhizosphere interactions

Rhizobacteria live around roots but also inside the cortical root tissues by utilizing organic substances released from root cells into the intercellular spaces and the root environment. The effects of metabolites of these rhizosphere-inhabiting bacteria on root physiology and plant development have hardly been studied. However, recent studies indicate that, depending on environmental factors and plant species, certain strains of rhizosphere Pseudomonas spp. and some of their metabolites such as HCN may inhibit or enhance plant establishment or inhibit development of plant disease. Cultural practices such as cropping frequency, no tillage, and soilless cultivation, as well as edaphic factors seem to determine these rhizosphere interactions.     

The influence of diffusion potentials across liposomal membranes on the fluorescence intensity of 1-anilinonaphthalene-8-sulphonate

The influence of diffusion potentials across different phospholipid membranes on the fluorescence intensity of 1-anilinonaphthalene-8-sulphonate (ANS) was studied. With liposomes or chloroform spheres covered with a monolayer of egg lecithin, no specific effects were found. With liposomes of soy-bean phospholipids, generation of a diffusion potential leads to an enhancement or decrease, depending on the direction of the potential, of the intensity of ANS fluorescence. This effect is mainly due to a change in quantum yield of the bound ANS. These data support a mechanism according to which ANS molecules are pushed into or pulled out of the membrane by a potential, but not an electrophoretic one in which the potential causes movement of ANS across the membrane.     

From intensively agricultural practices to hay-making without fertilization

In the valley of the Dutch brook Drentsche A formerly fertilized lots came under hay-making without fertilization practices. The vegetation at the beginning of the experiments varied depending on the intensity of former agricultural practices.Clustering revealed unidirectional successional lines in all lots with relatively large changes in the first four years. Changes still occur after 30 years of unfertilized hay-making. Changes concerning vegetation types as well as increasing or appearing and decreasing or disappearing species suggest a diminishing availability of nutrients as the main environmental process. Therefore it is concluded that after a period of fertilizing some restoration of plant communities associated with former agricultural practices is possible.Variation already present within lots nearly always remained and in one lot a divarication of successional lines could be recorded, probably correlated with hydrological differences.The nomenclature of taxa is according to Heukels & van Ooststroom (1977), that of syntaxa according to Westhoff & den Held (1969), Ellenberg (1978) and Everts et al. (1980).The authors would like to thank Drs. N. Schotsman, Drs. A. Zeevalking-van Yperen, Drs. L. Rohof, Drs. P. Struyk, Drs. G. Boedeltje, Mrs. E. Hermans and Mr. W. van der Lans for recording the permanent plots, to Mr. E. Leeuwinga for drawing the figures and to Dr. S. Daan for correcting the English text.     

The heterogeneity of rat-liver mitochondrial DNA

Two types of mitochondrial DNA (mtDNA) can be distinquished in an inbred strain of rats of the Wistar type. The population of DNA molecules of the liver of one single rat is homogeneous. This was shown for a number of 100 animals and confirms the data of other investigators. The two types of mitochondrial DNA, designated A and B, differ in their number of cleavage sites for the restriction endonucleases Eco RI (2sites), Hind II (1 site) and Hha I (1 site). No differences were found for the restriction enzymes Bam HI, Hap II, Hind III and Hpa I. The degree of sequence divergence of the two types of DNA is calculated to be roughly 5% on the basis of these observations. From 20 rats part of the liver was taken and the mtDNA was characterized. Heterologous and homologous crosses between type A and type B rats were made. Analysis of the offspring revealed strictly maternal inheritance of the A and B mtDNA traits. For purposes of base-sequence analysis and RNA.DNA hybridization the strain could easily be "purified" genetically.     

Concerted Efforts to Control or Eliminate Neglected Tropical Diseases: How Much Health Will Be Gained?

Background

The London Declaration (2012) was formulated to support and focus the control and elimination of ten neglected tropical diseases (NTDs), with targets for 2020 as formulated by the WHO Roadmap. Five NTDs (lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths and trachoma) are to be controlled by preventive chemotherapy (PCT), and four (Chagas’ disease, human African trypanosomiasis, leprosy and visceral leishmaniasis) by innovative and intensified disease management (IDM). Guinea worm, virtually eradicated, is not considered here. We aim to estimate the global health impact of meeting these targets in terms of averted morbidity, mortality, and disability adjusted life years (DALYs).

Methods

The Global Burden of Disease (GBD) 2010 study provides prevalence and burden estimates for all nine NTDs in 1990 and 2010, by country, age and sex, which were taken as the basis for our calculations. Estimates for other years were obtained by interpolating between 1990 (or the start-year of large-scale control efforts) and 2010, and further extrapolating until 2030, such that the 2020 targets were met. The NTD disease manifestations considered in the GBD study were analyzed as either reversible or irreversible. Health impacts were assessed by comparing the results of achieving the targets with the counterfactual, construed as the health burden had the 1990 (or 2010 if higher) situation continued unabated.

Principle Findings/Conclusions

Our calculations show that meeting the targets will lead to about 600 million averted DALYs in the period 2011–2030, nearly equally distributed between PCT and IDM-NTDs, with the health gain amongst PCT-NTDs mostly (96%) due to averted disability and amongst IDM-NTDs largely (95%) from averted mortality. These health gains include about 150 million averted irreversible disease manifestations (e.g. blindness) and 5 million averted deaths. Control of soil-transmitted helminths accounts for one third of all averted DALYs. We conclude that the projected health impact of the London Declaration justifies the required efforts.     

Peatland vascular plant functional types affect dissolved organic matter chemistry

Aims

The readily available global rock phosphate (P) reserves may be depleted within the next 50–130 years warranting careful use of this finite resource. We develop a model that allows us to assess a range of P fertiliser and soil management strategies for Barley in order to find which one maximises plant P uptake under certain climate conditions.

Methods

Our model describes the development of the P and water profiles within the soil. Current cultivation techniques such as ploughing and reduced till gradient are simulated along with fertiliser options to feed the top soil or the soil right below the seed.

Results

Our model was able to fit data from two barley field trials, achieving a good fit at early growth stages but a poor fit at late growth stages, where the model underestimated plant P uptake. A well-mixed soil (inverted and 25 cm ploughing) is important for optimal plant P uptake and provides the best environment for the root system.

Conclusions

The model is sensitive to the initial state of P and its distribution within the soil profile; experimental parameters which are sparsely measured. The combination of modelling and experimental data provides useful agricultural predictions for site specific locations.