1,991 research outputs found
CONFINED ANIMAL PRODUCTION AND MANURE NUTRIENTS
Using data from the Census of Agriculture on animal inventory and sales, we estimate manure nutrient production on farms with confined livestock. Using reported on-farm production of crops on these same farms, we estimate the nutrient uptake for major field crops and pastureland. This enables us to examine the balance between manure nutrient production and nutrient need measured by crop uptake at a farm level. Examination at alternative spatial scales, shows that 75 percent of counties in the U.S. have farms that produce more manure nutrients than can be assimilated on the farm of production (excess nitrogen).The vast majority of the counties that produce excess nitrogen have adequate land in the county to spread the manure at agronomic rates. Thus, proposed policies that focus on land application have the potential to limit manure nutrient movement to waterways in most areas, if properly managed. However, moving manure to crop farms that formerly had not used manure will increase costs. There were about 5 percent of counties where the manure nitrogen production levels from confined animal production exceeded half the nitrogen assimilative capacity of all the cropland and pastureland in the county. These areas have the greatest need for mechanisms to encourage off-farm solutions to utilize manure as a feedstock for commercial enterprises or central processing.Livestock Production/Industries,
CONFINED ANIMAL PRODUCTION AND MANURE NUTRIENTS
Census of agriculture data were used to estimate manure nutrient production and the capacity of cropland and pastureland to assimilate nutrients. Most farms (78 percent for nitrogen and 69 percent for phosphorus) have adequate land on which it is physically feasible to apply the manure produced onfarm at agronomic rates. (The costs of applying manure at these rates have not been assessed). Even so, manure that is produced on operations that cannot fully apply it to their own land at agronomic rates accounts for 60 percent of the Nation's manure nitrogen and 70 percent of the manure phosphorus. In these cases, most counties with farms that produce "excess" nutrients have adequate crop acres not associated with animal operations, but within the county, on which it is feasible to spread the manure at agronomic rates. However, barriers to moving manure to other farms need to be studied. About 20 percent of the Nation's onfarm excess manure nitrogen is produced in counties that have insufficient cropland for its application at agronomic rates (23 percent for phosphorus). For areas without adequate land, alternatives to local land application-such as energy production-will need to be developed.Manure, nutrients, manure nutrients, animal waste, confined livestock, confined animal feeding operation, CAFO, feedlot beef, dairy cows, swine, poultry, animal unit, manure nitrogen, manure phosphorus, water quality, Livestock Production/Industries,
Likelihood Ratio Test process for Quantitative Trait Locus detection
International audienceWe consider the likelihood ratio test (LRT) process related to the test of the absence of QTL (a QTL denotes a quantitative trait locus, i.e. a gene with quantitative effect on a trait) on the interval [0,T] representing a chromosome. The observation is the trait and the composition of the genome at some locations called ''markers''. We give the asymptotic distribution of this LRT process under the null hypothesis that there is no QTL on [0,T] and under local alternatives with a QTL at t* on [0,T]. We show that the LRT is asymptotically the square of some Gaussian process. We give a description of this process as an '' non-linear interpolated and normalized process ''. We propose a simple method to calculate the maximum of the LRT process using only statistics on markers and their ratio. This gives a new method to calculate thresholds for QTL detection
VIPERdb: a relational database for structural virology
VIPERdb () is a database for icosahedral virus capsid structures. Our aim is to provide a comprehensive resource specific to the needs of the structural virology community, with an emphasis on the description and comparison of derived data from structural and energetic analyses of capsids. A relational database implementation based on a schema for macromolecular structure makes the data highly accessible to the user, allowing detailed queries at the atomic level. Together with curation practices that maintain data uniformity, this will facilitate structural bioinformatics studies of virus capsids. User friendly search, visualization and educational tools on the website allow both structural and derived data to be examined easily and extensively. Links to relevant literature, sequence and taxonomy databases are provided for each entry
Perturb-Seq: Dissecting Molecular Circuits with Scalable Single-Cell RNA Profiling of Pooled Genetic Screens
Genetic screens help infer gene function in mammalian cells, but it has remained difficult to assay complex phenotypes—such as transcriptional profiles—at scale. Here, we develop Perturb-seq, combining single-cell RNA sequencing (RNA-seq) and clustered regularly interspaced short palindromic repeats (CRISPR)-based perturbations to perform many such assays in a pool. We demonstrate Perturb-seq by analyzing 200,000 cells in immune cells and cell lines, focusing on transcription factors regulating the response of dendritic cells to lipopolysaccharide (LPS). Perturb-seq accurately identifies individual gene targets, gene signatures, and cell states affected by individual perturbations and their genetic interactions. We posit new functions for regulators of differentiation, the anti-viral response, and mitochondrial function during immune activation. By decomposing many high content measurements into the effects of perturbations, their interactions, and diverse cell metadata, Perturb-seq dramatically increases the scope of pooled genomic assays. Keywords:
single-cell RNA-seq; pooled screen; CRISPR; epistasis; genetic interaction
SNP Genotyping Defines Complex Gene-Flow Boundaries Among African Malaria Vector Mosquitoes
Mosquitoes in the Anopheles gambiae complex show rapid ecological and behavioral diversification, traits that promote malaria transmission and complicate vector control efforts. A high-density, genome-wide mosquito SNP-genotyping array allowed mapping of genomic differentiation between populations and species that exhibit varying levels of reproductive isolation. Regions near centromeres or within polymorphic inversions exhibited the greatest genetic divergence, but divergence was also observed elsewhere in the genomes. Signals of natural selection within populations were overrepresented among genomic regions that are differentiated between populations, implying that differentiation is often driven by population-specific selective events. Complex genomic differentiation among speciating vector mosquito populations implies that tools for genome-wide monitoring of population structure will prove useful for the advancement of malaria eradication
RNF43 is frequently mutated in colorectal and endometrial cancers
We report somatic mutations of RNF43 in over 18% of colorectal adenocarcinomas and endometrial carcinomas. RNF43 encodes an E3 ubiquitin ligase that negatively regulates Wnt signaling. Truncating mutations of RNF43 are more prevalent in microsatellite-unstable tumors and show mutual exclusivity with inactivating APC mutations in colorectal adenocarcinomas. These results indicate that RNF43 is one of the most commonly mutated genes in colorectal and endometrial cancers.National Human Genome Research Institute (U.S.) (Grant U54HG003067
Cell Lineages and the Logic of Proliferative Control
It is widely accepted that the growth and regeneration of tissues and organs is tightly controlled. Although experimental studies are beginning to reveal molecular mechanisms underlying such control, there is still very little known about the control strategies themselves. Here, we consider how secreted negative feedback factors (“chalones”) may be used to control the output of multistage cell lineages, as exemplified by the actions of GDF11 and activin in a self-renewing neural tissue, the mammalian olfactory epithelium (OE). We begin by specifying performance objectives—what, precisely, is being controlled, and to what degree—and go on to calculate how well different types of feedback configurations, feedback sensitivities, and tissue architectures achieve control. Ultimately, we show that many features of the OE—the number of feedback loops, the cellular processes targeted by feedback, even the location of progenitor cells within the tissue—fit with expectations for the best possible control. In so doing, we also show that certain distinctions that are commonly drawn among cells and molecules—such as whether a cell is a stem cell or transit-amplifying cell, or whether a molecule is a growth inhibitor or stimulator—may be the consequences of control, and not a reflection of intrinsic differences in cellular or molecular character
Retroviral DNA Integration: ASLV, HIV, and MLV Show Distinct Target Site Preferences
The completion of the human genome sequence has made possible genome-wide studies of retroviral DNA integration. Here we report an analysis of 3,127 integration site sequences from human cells. We compared retroviral vectors derived from human immunodeficiency virus (HIV), avian sarcoma-leukosis virus (ASLV), and murine leukemia virus (MLV). Effects of gene activity on integration targeting were assessed by transcriptional profiling of infected cells. Integration by HIV vectors, analyzed in two primary cell types and several cell lines, strongly favored active genes. An analysis of the effects of tissue-specific transcription showed that it resulted in tissue-specific integration targeting by HIV, though the effect was quantitatively modest. Chromosomal regions rich in expressed genes were favored for HIV integration, but these regions were found to be interleaved with unfavorable regions at CpG islands. MLV vectors showed a strong bias in favor of integration near transcription start sites, as reported previously. ASLV vectors showed only a weak preference for active genes and no preference for transcription start regions. Thus, each of the three retroviruses studied showed unique integration site preferences, suggesting that virus-specific binding of integration complexes to chromatin features likely guides site selection
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