Reduction of the frequency of herbaceous roots as an effect of soil compaction induced by heavy grazing in rangelands of SW Spain

Rangelands in SW Spain constitute the most extensive ranching system on the Iberian Peninsula. During the last few decades, a significant increase in livestock numbers, along with a progressive substitution of cattle for sheep, have led to land degradation processes such as the reduction of grass cover and increased soil compaction in heavily grazed areas. Nevertheless, a better understanding of how soil compaction affects grass production is still needed. In this study, some of the effects of soil compaction due to heavy grazing are analysed, mainly the reduction of the frequency of herbaceous roots and its relationships with bulk density and soil penetration resistance. The study was carried out in 22 fenced areas grazed under different intensities (animal stocking rates: 0.19-15.76 AU ha−1). Undisturbed soil core and bulk samples were collected at 3 depth intervals in order to determine select soil properties (texture, organic matter content, and bulk density). Additionally, soil penetration resistance was quantified at 890 random points at different depths and soil moisture contents. Frequency of herbaceous roots was estimated for each soil horizon in 47 soil profiles and categorized into 4 classes: none, few, common and many. Results showed negative relationships between bulk density (> 10 cm depth) and the content of soil organic matter from 0 to 5 cm (r =−0.061, p < 0.05) and 5-10 m depth (r = −0.824, p < 0.005). Furthermore, a tendency for decreasing mean values of soil penetration resistance as the frequency of herbaceous roots increased was also observed. The values observed confirm that soil compaction provoked by an excessive number of animals reduced the quantity of herbaceous roots. The value of 2 MPa traditionally accepted as restrictive for root growth is discussed. Findings presented here could be of interest for policy makers and farm owners to guide decisions about optimum animal stocking rates

An integrative approach for building personalized gene regulatory networks for precision medicine

Only a small fraction of patients respond to the drug prescribed to treat their disease, which means that most are at risk of unnecessary exposure to side effects through ineffective drugs. This inter-individual variation in drug response is driven by differences in gene interactions caused by each patient's genetic background, environmental exposures, and the proportions of specific cell types involved in disease. These gene interactions can now be captured by building gene regulatory networks, by taking advantage of RNA velocity (the time derivative of the gene expression state), the ability to study hundreds of thousands of cells simultaneously, and the falling price of single-cell sequencing. Here, we propose an integrative approach that leverages these recent advances in single-cell data with the sensitivity of bulk data to enable the reconstruction of personalized, cell-type- and context-specific gene regulatory networks. We expect this approach will allow the prioritization of key driver genes for specific diseases and will provide knowledge that opens new avenues towards improved personalized healthcare

A Table of nuclear moment data /

"Stable Isotope Research and Production Division.""Isotope Analysis Methods Laboratory.""February 1, 1955."Bibliographical references: p. 13-16.Operated by Carbide and Carbon Chemicals CompanyMode of access: Internet