279 research outputs found

    The Anaphase-Promoting Complex (APC) ubiquitin ligase affects chemosensory behavior in \u3cem\u3eC. elegans\u3c/em\u3e

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    The regulation of fundamental aspects of neurobiological function has been linked to the ubiquitin signaling system (USS), which regulates the degradation and activity of proteins and is catalyzed by E1, E2, and E3 enzymes. The Anaphase-Promoting Complex (APC) is a multi-subunit E3 ubiquitin ligase that controls diverse developmental and signaling processes in post-mitotic neurons; however, potential roles for the APC in sensory function have yet to be explored. In this study, we examined the effect of the APC ubiquitin ligase on chemosensation in Caenorhabditis elegans by testing chemotaxis to the volatile odorants, diacetyl, pyrazine, and isoamyl alcohol, to which wild-type worms are attracted. Animals with loss of function mutations in either of two alleles (g48 and ye143) of the gene encoding the APC subunit EMB-27 APC6 showed increased chemotaxis towards diacetyl and pyrazine, odorants sensed by AWA neurons, but exhibited normal chemotaxis to isoamyl alcohol, which is sensed by AWC neurons. The statistically significant increase in chemotaxis in the emb-27 APC6 mutants suggests that the APC inhibits AWA-mediated chemosensation in C. elegans. Increased chemotaxis to pyrazine was also seen with mutants lacking another essential APC subunit, MAT-2 APC1; however, mat-2 APC1 mutants exhibited wild type responses to diacetyl. The difference in responsiveness of these two APC subunit mutants may be due to differential strength of these hypomorphic alleles or may indicate the presence of functional sub-complexes of the APC at work in this process. These findings are the first evidence for APC-mediated regulation of chemosensation and lay the groundwork for further studies aimed at identifying the expression levels, function, and targets of the APC in specific sensory neurons. Because of the similarity between human and C. elegans nervous systems, the role of the APC in sensory neurons may also advance our understanding of human sensory function and disease

    Microstructure versus Size: Mechanical Properties of Electroplated Single Crystalline Cu Nanopillars

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    We report results of uniaxial compression experiments on single-crystalline Cu nanopillars with nonzero initial dislocation densities produced without focused ion beam (FIB). Remarkably, we find the same power-law size-driven strengthening as FIB-fabricated face-centered cubic micropillars. TEM analysis reveals that initial dislocation density in our FIB-less pillars and those produced by FIB are on the order of 10^(14)  m^(-2) suggesting that mechanical response of nanoscale crystals is a stronger function of initial microstructure than of size regardless of fabrication method

    In situ characterization of vertically oriented carbon nanofibers for three-dimensional nano-electro-mechanical device applications

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    We have performed mechanical and electrical characterization of individual as-grown, vertically oriented carbon nanofibers (CNFs) using in situ techniques, where such high-aspect-ratio, nanoscale structures are of interest for three-dimensional (3D) electronics, in particular 3D nano-electro-mechanical-systems (NEMS). Nanoindentation and uniaxial compression tests conducted in an in situ nanomechanical instrument, SEMentor, suggest that the CNFs undergo severe bending prior to fracture, which always occurs close to the bottom rather than at the substrate–tube interface, suggesting that the CNFs are well adhered to the substrate. This is also consistent with bending tests on individual tubes which indicated that bending angles as large as ~70° could be accommodated elastically. In situ electrical transport measurements revealed that the CNFs grown on refractory metallic nitride buffer layers were conducting via the sidewalls, whereas those synthesized directly on Si were electrically unsuitable for low-voltage dc NEMS applications. Electrostatic actuation was also demonstrated with a nanoprobe in close proximity to a single CNF and suggests that such structures are attractive for nonvolatile memory applications. Since the magnitude of the actuation voltage is intimately dictated by the physical characteristics of the CNFs, such as diameter and length, we also addressed the ability to tune these parameters, to some extent, by adjusting the plasma-enhanced chemical vapor deposition growth parameters with this bottom-up synthesis approach

    Climate Variability and Human Migration in the Netherlands, 1865-1937

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    Human migration is frequently cited as a potential social outcome of climate change and variability, and these effects are often assumed to be stronger in the past when economies were less developed and markets more localized. Yet, few studies have used historical data to test the relationship between climate and migration directly. In addition, the results of recent studies that link demographic and climate data are not consistent with conventional narratives of displacement responses. Using longitudinal individual-level demographic data from the Historical Sample of the Netherlands (HSN) and climate data that cover the same period, we examine the effects of climate variability on migration using event history models. Only internal moves in the later period and for certain social groups are associated with negative climate conditions, and the strength and direction of the observed effects change over time. International moves decrease with extreme rainfall, suggesting that the complex relationships between climate and migration that have been observed for contemporary populations extend into the nineteenth century

    In The Best Interest Of The (Adult) Child: Ideas About Kinship Care Of Older Adults

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    This article uses a qualitative, ethnographic approach to examine the experiences older adults and their kin, as the older adult engages in relocation. Studies looking at caregiving by kin for older adults highlight burdens for the adult child. This study offers a life course perspective on kinship care, analyzing older adults’ decisions’ to move. It was found that many older adults are strongly influenced by the desire to not be cared for by their kin as well as to select housing near their existing social network, which might exclude kin. In conclusion, policy implications are discussed

    Impact of Immigrant Entrepreneurs and Workers in Leisure and Hospitality Businesses: Massachusetts and New England

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    This report examines the role and impact of immigrant entrepreneurs and workers on Leisure and Hospitality businesses in New England, particularly Massachusetts. A significant portion of state economies in New England, especially in Massachusetts, relies heavily on the employment of the foreign-born. As the native workforce ages and population growth declines, businesses are becoming increasingly dependent upon the availability of the foreign-born. This development has facilitated an increasingly significant presence and role of immigrant entrepreneurs in Leisure and Hospitality businesses that is documented for the first time in this report

    Intergenerational Transmission of Reproductive Behavior during the Demographic Transition

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    New evidence from the Utah Population Database (updp) reveals that at the onset of the fertility transition, reproductive behavior was transmitted across generations—between women and their mothers, as well as between women and their husbands\u27 family of origin. Age at marriage, age at last birth, and the number of children ever born are positively correlated in the data, most strongly among first-born daughters and among cohorts born later in the fertility transition. Intergenerational ties, including the presence of mothers and mothers-in-law, influenced the hazard of progressing to a next birth. The findings suggest that the practice of parity-dependent marital fertility control and inter-birth spacing behavior derived, in part, from the previous generation and that the potential for mothers and mothers-in-law to help in the rearing of children encouraged higher marital fertility

    Cell Model System for Glucocorticoid-Induced Osteoporosis

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    Dexamethasone, a corticosteroid that inhibits inflammation, is commonly used for the treatment of arthritis. However, glucocorticoid-induced osteoporosis is a side effect that commonly occurs after dexamethasone treatment. One of the mechanisms by which glucocorticoids are thought to suppress bone formation is through their effect on the wnt/ Ăź-catenin signaling pathway. The wnt/ Ăź-catenin pathway is essential in the formation of new osteoblasts and the prevention of osteoblast apoptosis. However, treatment with dexamethasone is thought to destabilize and inhibit nuclear translocation of Ăź-catenin, decreasing the survival of osteoblasts. By using precursor mouse osteoblast MC3T3 cells, we will analyze antisense morpholino oligonucleotide targeted to Col11a1 as a potential treatment to reverse or block the detrimental effects of dexamethasone on the wnt signaling pathway. MC3T3 cells will be exposed to different treatments in vitro, then aspects of the cell cycle will be analyzed by markers of apoptosis, specific signaling pathways, and cell proliferation rates. While the data obtained in this experiment is relevant to human cell functioning, future research with human cells will strengthen this line of investigation further and establish greater relevance to human health
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