1,252 research outputs found
Why are rhizobial symbiosis genes mobile?
Rhizobia are one of the most important and best studied groups of bacterial symbionts. They are defined by their ability to establish nitrogen-fixing intracellular infections within plant hosts. One surprising feature of this symbiosis is that the bacterial genes required for this complex trait are not fixed within the chromosome, but are encoded on mobile genetic elements (MGEs), namely plasmids or integrative and conjugative elements. Evidence suggests that many of these elements are actively mobilizing within rhizobial populations, suggesting that regular symbiosis gene transfer is part of the ecology of rhizobial symbionts. At first glance, this is counterintuitive. The symbiosis trait is highly complex, multipartite and tightly coevolved with the legume hosts, while transfer of genes can be costly and disrupt coadaptation between the chromosome and the symbiosis genes. However, horizontal gene transfer is a process driven not only by the interests of the host bacterium, but also, and perhaps predominantly, by the interests of the MGEs that facilitate it. Thus understanding the role of horizontal gene transfer in the rhizobium–legume symbiosis requires a ‘mobile genetic element's-eye view' on the ecology and evolution of this important symbiosis
Making food safety interventions benefit the most vulnerable urban consumers in Vietnam and Cambodia
High Energy Gamma Ray Production from Proton Induced Reactions on D, C, Zn, Pb at Incident Energies of 104, 145, and 195 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Percolation on two- and three-dimensional lattices
In this work we apply a highly efficient Monte Carlo algorithm recently
proposed by Newman and Ziff to treat percolation problems. The site and bond
percolation are studied on a number of lattices in two and three dimensions.
Quite good results for the wrapping probabilities, correlation length critical
exponent and critical concentration are obtained for the square, simple cubic,
HCP and hexagonal lattices by using relatively small systems. We also confirm
the universal aspect of the wrapping probabilities regarding site and bond
dilution.Comment: 15 pages, 6 figures, 3 table
Predictions for the 4 GeV TJNAF inclusive electron scattering experiment and for FSI effects in EMC ratios
We express nuclear structure functions as generalized convolutions of
the structure function of a nucleon and of a nucleus, composed of
point-nucleons. In computations of the latter we include Final State
Interactions and results for are compared with a few directly measured
data on C and Fe. The above are primarily used for predictions of the
TJNAF 89-008 inclusive scattering experiment of 4 GeV electrons on various
targets. Those cover a broad angular, and correspondingly wide range,
where the nucleon-inelastic part dominates large sections of the covered
kinematics. The same model has been applied to the study of hitherto neglected
Final State Interaction effects in the nuclear component in EMC ratios in the
region .Comment: 12 page
Transgenic mice expressing high plasma concentrations of human apolipoprotein B100 and lipoprotein(a)
The B apolipoproteins, apo-B48 and apo-B100, are key structural proteins in those classes of lipoproteins considered to be atherogenic [e.g., chylomicron remnants, \u3b2-VLDL, LDL, oxidized LDL, and Lp(a)]. Here we describe the development of transgenic mice expressing high levels of human apo-B48 and apo-B100. A 79.5-kb human genomic DNA fragment containing the entire human apo-B gene was isolated from a P1 bacteriophage library and microinjected into fertilized mouse eggs. 16 transgenic founders expressing human apo-B were generated, and the animals with the highest expression had plasma apo-B100 levels nearly as high as those of normolipidemic humans ( 3c50 mg/dl). The human apo-B100 in transgenic mouse plasma was present largely in lipoproteins of the LDL class as shown by agarose gel electrophoresis, chromatography on a Superose 6 column, and density gradient ultracentrifugation. When the human apo-B transgenic founders were crossed with transgenic mice expressing human apo(a), the offspring that expressed both transgenes had high plasma levels of human Lp(a). Both the human apo-B and Lp(a) transgenic mice will be valuable resources for studying apo-B metabolism and the role of apo-B and Lp(a) in atherosclerosis
Technoscience and the modernization of freshwater fisheries assessment and management
Inland fisheries assessment and management are challenging given the inherent com-
plexity of working in diverse habitats (e.g., rivers, lakes, wetlands) that are dynamic
on organisms that are often cryptic and where fishers are often highly mobile. Yet,
technoscience is offering new tools that have the potential to reimagine how inland
fisheries are assessed and managed. So-called ‘‘technoscience’’ refers to instances in
which science and technology unfurl together, offering novel ways of spurring and
achieving meaningful change. This paper considers the role of technoscience and its
potential for modernizing the assessment and management of inland fisheries. It first
explores technoscience and its potential benefits, followed by presentation of a series
of synopses that explore the application (both successes and challenges) of new tech-
nologies such as environmental DNA (eDNA), genomics, electronic tags, drones, phone
apps, iEcology, and artificial intelligence to assessment and management. The paper
also considers the challenges and barriers that exist in adopting new technologies. The
paper concludes with a provocative assessment of the potential of technoscience to
reform and modernize inland fisheries assessment and management. Although these
tools are increasingly being embraced, there is a lack of platforms for aggregating these
data streams and providing managers with actionable information in a timely manner.
The ideas presented here should serve as a catalyst for beginning to work collectively
and collaboratively towards fisheries assessment and management systems that harness
the power of technology and serve to modernize inland fisheries management. Such
transformation is urgently needed given the dynamic nature of environmental change,
the evolving threat matrix facing inland waters, and the complex behavior of fishers.
Quite simply, a dynamic world demands dynamic fisheries management; technoscience
has made that within reach.publishedVersio
Testing Logselfsimilarity of Soil Particle Size Distribution: Simulation with Minimum Inputs
Particle size distribution (PSD) greatly influences other soil physical properties. A detailed textural analysis is time-consuming and expensive. Soil texture is commonly reported in terms of mass percentages of a small number of size fractions (typically, clay, silt and sand). A method to simulate the PSD from such a poor description or even from the poorest description, consisting in the mass percentages of only two soil size fractions, would be extremly useful for prediction purposes. The goal of this paper is to simulate soil PSDs from the minimum number of inputs, i.e., two and three textural fraction contents, by using a logselfsimilar model and an iterated function system constructed with these data. High quality data on 171 soils are used. Additionally, the characterization of soil texture by entropy-based parameters provided by the model is tested. Results indicate that the logselfsimilar model may be a useful tool to simulate PSD for the construction of pedotransfer functions related to other soil properties when textural information is limited to moderate textural data
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