1,022 research outputs found
Nitric oxide induces chromatin remodelling in the developing central nervous system
The development of the nervous system is a complex task that involves precise connections
between billions of neurons. This is achieved, at least in part, by the overproduction of neurons
and the survival of a select few that compete for limited survival and growth promoting factors,
such as neurotrophic factors. The neurotrophin brain-derived neurotrophin factor (BDNF) has
been shown to play an important role in proliferation and differentiation of cortical neuronal
precursors (Bartkowska et al 2007). Moreover, BDNF induces binding of the transcription factor
CREB to gene promoters in a nitric oxide (NO)-dependent manner (Riccio et al 2006). NO
positively regulates a large number of transcription factors and genes in the nervous system
(Hemish et al 2003; Dhakshinamoorthy et al 2007). I have demonstrated that NO achieves this
broad level of gene regulation by influencing chromatin remodelling. My data also show that NO
accumulates within the nucleus of cortical neurons upon BDNF stimulation, thereby inducing Snitrosylation
of a wide array of nuclear proteins. S-nitrosylation of histone deacetylase 2
(HDAC2) decreases its affinity for chromatin, leading to increased histone acetylation levels.
This NO-dependent regulation of HDAC2 promotes changes in endogenous gene expression and
affects the dendritic length of cortical neurons
DAIRY FARM DECISIONS ON HOW TO PROCEED IN THE FACE OF TB
By early 2000, the number of commercial livestock herds in Michigan with bovine tuberculosis (TB) had increased to the point that policy makers were considering alternative ways to enable farmers to continue production with access to markets while eliminating TB and protecting the public's health. If at least one animal on a farm is found to have TB, a farmer currently has two choices about the future assuming the goal is to stay in the livestock business. Alternative one is depopulation; all animals are removed to a state facility, slaughtered, and tested. A new herd may be purchased after a state supervised clean up and waiting period is completed; this may take one year. Alternative two is test and remove; a recurring series of testing is initiated, but only individual reactor or suspect animals are removed for slaughter and further testing. In both alternatives, regulations allow indemnity payments to be made to the owner by the state and federal governments. This paper analyzes the financial impact of each alternative on two dairy benchmark farms. One has 75 milk cows, the other 150. Monthly cash flow projections for two years were made using FINFLO. A base projection was compared to the above alternatives assuming constant herd size (except for the impact of TB) and constant price levels. The main goal was to illustrate how a farmer might analyze the alternatives if faced with TB infected animals. The 75 cow farm started with 34,230 by December 31, 2001. Ending cash after two years for depopulation or test and remove were 15,801, respectively. The 75 cow farm started with a net worth of 66,542 over the two years. For depopulation or test and remove, the change in net worth by the end of 2001 was 48,256, respectively. The 150 cow farm started with 40,437 by December 31, 2001. Ending cash after two years for depopulation or test and remove were 13,290, respectively. The 150 cow farm started with a net worth of 31,765 over the two years. For depopulation or test and remove, the change in net worth by the end of 2001 was -1,925, respectively. Benchmark model farms will not exactly fit any particular farm. Each owner faced with TB should make their own projections using their unique situation and timing of cash flows. Once an alternative is adopted, monthly financial comparison sheets can be helpful in managing the transition to TB free status.Livestock Production/Industries,
The composition of phosphate granules in the digestive glands of marine prosobranch gastropods: variation in relation to taxonomy
The composition of some 1150 phosphate granules in the digestive glands of over 40 species of marine prosobranch gastropods has been surveyed using a simple preparation technique and semiquantitative SEM x-ray microanalysis. Spectral peaks for Mg, K, Ca, Mn, Fe and Zn were compared to that of P. Four major types of phosphate granule can be recognised, each generally characteristic of a taxonomic grouping: high Mg in archaeogastropods and littorinids, multiple metal in higher mesogastropods, and, in neogastropods, Mg-Ca in muricoideans and high Zn in buccinoideans. At least one Conus species (C. ventricosus) has high-Mg granules. Some causes of variation in granule composition are discussed: speculatively, it is suggested a palaeoenvironmental influence seems possible.info:eu-repo/semantics/publishedVersio
Genetic insights into immune mechanisms of Alzheimer's and Parkinson's disease
Microglia, the macrophages of the brain, are vital for brain homeostasis and have been implicated in a broad range of brain disorders. Neuroinflammation has gained traction as a possible therapeutic target for neurodegeneration, however, the precise function of microglia in specific neurodegenerative disorders is an ongoing area of research. Genetic studies offer valuable insights into understanding causality, rather than merely observing a correlation. Genome-wide association studies (GWAS) have identified many genetic loci that are linked to susceptibility to neurodegenerative disorders. (Post)-GWAS studies have determined that microglia likely play an important role in the development of Alzheimer's disease (AD) and Parkinson's disease (PD). The process of understanding how individual GWAS risk loci affect microglia function and mediate susceptibility is complex. A rapidly growing number of publications with genomic datasets and computational tools have formulated new hypotheses that guide the biological interpretation of AD and PD genetic risk. In this review, we discuss the key concepts and challenges in the post-GWAS interpretation of AD and PD GWAS risk alleles. Post-GWAS challenges include the identification of target cell (sub)type(s), causal variants, and target genes. Crucially, the prediction of GWAS-identified disease-risk cell types, variants and genes require validation and functional testing to understand the biological consequences within the pathology of the disorders. Many AD and PD risk genes are highly pleiotropic and perform multiple important functions that might not be equally relevant for the mechanisms by which GWAS risk alleles exert their effect(s). Ultimately, many GWAS risk alleles exert their effect by changing microglia function, thereby altering the pathophysiology of these disorders, and hence, we believe that modelling this context is crucial for a deepened understanding of these disorders
Theory of Suspension Segregation in Partially Filled Horizontal Rotating Cylinders
It is shown that a suspension of particles in a partially-filled, horizontal,
rotating cylinder is linearly unstable towards axial segregation and an
undulation of the free surface at large enough particle concentrations. Relying
on the shear-induced diffusion of particles, concentration-dependent viscosity,
and the existence of a free surface, our theory provides an explanation of the
experiments of Tirumkudulu et al., Phys. Fluids 11, 507-509 (1999); ibid. 12,
1615 (2000).Comment: Accepted for publication in Phys Fluids (Lett) 10 pages, two eps
figure
The origin of centennial- to millennial-scale chronological gaps in storm emplaced beach ridge plains
Recent studies of tropical cyclone surge and wave emplaced beach ridge plains have shown that these sequences often contain centennial to millennial scale gaps in their chronologies. Two explanations for the gaps exist — they are due to erosion, or alternatively a cessation or substantial slowing of depositional processes suggestive of a quieter phase in intense storm activity. Differentiating between the two is important for uncovering reliable long-term storm histories from these sequences. We use landform morphology, sediment texture and luminescence chronology to determine the origin of substantial chronological gaps in a plain containing more than 100 shore-parallel ridges composed of fine-grained sand located in northeast Australia. We identify and describe the characteristics associated with both erosional and non-erosional gaps. The erosional gaps are associated with changes in orientation between ridge sets and often a high ridge with hummocky topography that appears to have been disturbed by aeolian activity. River floods likely caused the partial erosion of ridge sets. Non-erosional gaps do not display these morphological characteristics and are likely associated with quiescence in severe tropical cyclone activity. These geomorphic and chronological signatures can be used to identify different sorts of gaps in other ridge plains and are an important tool in the reconstruction of long-term storm histories from these coastal landforms. The data also suggests that fine-grained ridges can, like their coarse-grained counterparts, be predominantly deposited by storm waves and surge and their texture need not necessarily be indicative of the processes responsible for ridge development
The statistics of particle velocities in dense granular flows
We present measurements of the particle velocity distribution in the flow of
granular material through vertical channels. Our study is confined to dense,
slow flows where the material shears like a fluid only in thin layers adjacent
to the walls, while a large core moves without continuous deformation, like a
solid. We find the velocity distribution to be non-Gaussian, anisotropic, and
to follow a power law at large velocities. Remarkably, the distribution is
identical in the fluid-like and solid-like regions. The velocity variance is
maximum at the core, defying predictions of hydrodynamic theories. We show
evidence of spatially correlated motion, and propose a mechanism for the
generation of fluctuational motion in the absence of shear.Comment: Submitted to Phys. Rev. Let
- …