Continuous growth of vimentin filaments in mouse fibroblasts

We have investigated the dynamics of intermediate filament assembly in vivo by following the fate of heterologous chicken vimentin subunits expressed under the control of an inducible promoter in transfected mouse fibroblasts. Using RNase protection, metabolic protein pulse-chase and immunofluorescence microscopy, we have examined the fate of newly assembled subunits under physiological conditions in situ. Following induction and subsequent removal of inducer, chicken vimentin mRNA had a half-life of approximately 6 h while both chicken and mouse vimentin protein polymer had long half-lives--roughly equivalent to the cell generation time. Moreover, following deinduction, chicken vimentin immunolocalization progressed from a continuous (8-10 h chase) to a discontinuous (> or = 20 h chase) pattern. The continuous chicken vimentin staining reflects the uniform incorporation of chicken vimentin throughout the endogenous mouse vimentin network while the discontinuous or punctate chicken vimentin staining represents short interspersed segments of assembled chicken vimentin superimposed on the endogenous polymer. This punctate staining pattern of chicken vimentin was present throughout the entire array of intermediate filaments, with no bias toward the perinuclear region. These results are consistent with a continuous growth model of intermediate filament assembly, wherein subunit addition occurs at discrete sites located throughout the cytoskeleton

Outcomes Based Assessment of Universities

This study summarizes recent and continuing research conducted by the Center for College Affordability and Productivity (CCAP) on the metrics used for measuring college performance. Unlike other rankings, this study does not concentrate on the inputs of college education such as endowment size, number of faculty, or the educational preparation of students as measured by SAT scores, etc. Instead, it focuses on the outputs, namely the success of students after graduation. Using the names of entrants in Marquis Publishing's 2008 edition of Who's Who in America as our standard for measuring high levels of success, we collected the names of over 5,200 individuals, along with their educational background.This is more than a 5 percent sampling of all names listed in this standard reference work. From this sample, we then calculated which colleges produced the most successful graduates. The results thus far have been both fascinating and surprising.We have found that while going to top ranked schools as measured by standard college rankings does correlate with success, it is a weaker relationship than many may have previously believed. The study reveals that the "industry standard," U.S. News & World Report (USNWR) rankings, on the whole, is only weakly related to graduate success. This suggests that the characteristics contributing to the value of a student's education differ substantially from what is typically assumed. The goal of this study is not to serve as a definitive source for ranking and comparing colleges. Rather, the research presented herein will hopefully serve as both an impetus and road ma

Cell cycle regulation of a Xenopus Wee1-like kinase

Using a polymerase chain reaction-based strategy, we have isolated a gene encoding a Wee1-like kinase from Xenopus eggs. The recombinant Xenopus Wee1 protein efficiently phosphorylates Cdc2 exclusively on Tyr- 15 in a cyclin-dependent manner. The addition of exogenous Wee1 protein to Xenopus cell cycle extracts results in a dose-dependent delay of mitotic initiation that is accompanied by enhanced tyrosine phosphorylation of Cdc2. The activity of the Wee1 protein is highly regulated during the cell cycle: the interphase, underphosphorylated form of Wee1 (68 kDa) phosphorylates Cdc2 very efficiently, whereas the mitotic, hyperphosphorylated version (75 kDa) is weakly active as a Cdc2-specific tyrosine kinase. The down-modulation of Wee1 at mitosis is directly attributable to phosphorylation, since dephosphorylation with protein phosphatase 2A restores its kinase activity. During interphase, the activity of this Wee1 homolog does not vary in response to the presence of unreplicated DNA. The mitosis-specific phosphorylation of Wee1 is due to at least two distinct kinases: the Cdc2 protein and another activity (kinase X) that may correspond to an MPM-2 epitope kinase. These studies indicate that the down-regulation of Wee1-like kinase activity at mitosis is a multistep process that occurs after other biochemical reactions have signaled the successful completion of S phase

Nonperturbative three-point functions of the O(N) sigma model in the 1/N expansion at NLO

We present a calculation of the three-point functions of the O(N)-symmetric sigma model. The calculation is done nonperturbatively by means of a higher-order 1/N expansion combined with a tachyonic regularization which we proposed in previous publications. We use the results for calculating the standard model process ff -> H -> WW nonperturbatively in the quartic coupling of the scalar sector

Yucca Mountain Saturated Zone Carbon-14

This Scientific Investigation Plan (SIP) provides an overview of the work described in “Yucca Mountain Saturated Zone Carbon-14”, a proposal funded by the U.S. Department of Energy’s (DOE) Office of Repository Development under the UCCSN/YMP Co-op in support of the Science and Technology Initiatives. The objective of this work is to provide improved estimates of the time required for ground water to travel from the site of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, to the accessible environment

Influence of macrophage NF-kappaB activation on pneumococcal pneumonia

Streptococcus pneumoniae (pneumococcus) is commonly found in the nasopharynx of healthy individuals, yet it can be a serious pathogen, particularly in the lower respiratory tract, where it can cause severe pneumonia. During pneumococcal pneumonia, anti-bacterial host defense requires the orchestrated expression of innate immunity mediators, initiated by alveolar macrophages and dependent on transcriptional activity driven by Nuclear Factor-B (NF-B). Although the initiation of a pulmonary inflammatory response is critical to anti-pneumococcal defense during pneumonia, how differences in pneumococcal-macrophage interactions can influence this process is unclear. To determine the functional significance of varying macrophage NF-B activation, we examined macrophage responses to pneumococcal stimulation in culture and in mice. Macrophage-pneumococcal interactions resulted in the induction of varied NF-B activation. Two main pathways were revealed regarding host response and disease outcome. Pneumococci that induced efficient macrophage NF-B activation resulted in robust anti-pneumococcal lung defense and bacterial clearance. Conversely, failure to activate effective macrophage NF-B signaling resulted in an altered macrophage response of necroptosis. Overall, we conclude that varying levels of macrophage NF-B activation by pneumococcus can directly influence the severity of infection. Furthermore, inefficient macrophage NF-B activation can also have cytotoxic effects on these critical lung resident cells during pneumonia. The induction of macrophage NF-B activation by S. pneumoniae is as diverse as the population of pneumococcal isolates in the community. A unique host-pathogen interaction exists between pneumococcus and the alveolar macrophage that plays an important role in anti-pneumococcal defense during pneumonia and in the prevention of cytotoxic consequences induced by virulent pneumococci. This interaction suggests that therapies, which modulate NF-B activation, hold promise for augmenting resistance and ameliorating deleterious effects during pneumococcal pneumonia that could lead to the development of severe disease