911 research outputs found

    Culex tarsalis is a competent vector species for Cache Valley virus

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    Background: Cache Valley virus (CVV) is a mosquito-borne orthobunyavirus endemic in North America. The virus is an important agricultural pathogen leading to abortion and embryonic lethality in ruminant species, especially sheep. The importance of CVV in human public health has recently increased because of the report of severe neurotropic diseases. However, mosquito species responsible for transmission of the virus to humans remain to be determined. In this study, vector competence of three Culex species mosquitoes of public health importance, Culex pipiens, Cx. tarsalis and Cx. quinquefasciatus, was determined in order to identify potential bridge vector species responsible for the transmission of CVV from viremic vertebrate hosts to humans. Results: Variation of susceptibility to CVV was observed among selected Culex species mosquitoes tested in this study. Per os infection resulted in the establishment of infection and dissemination in Culex tarsalis, whereas Cx. pipiens and Cx. quinquefasciatus were highly refractory to CVV. Detection of viral RNA in saliva collected from infected Cx. tarsalis provided evidence supporting its role as a competent vector. Conclusions: Our study provided further understanding of the transmission cycles of CVV and identifies Cx. tarsalis as a competent vector

    Distinct Mechanisms for Induction and Tolerance Regulate the Immediate Early Genes Encoding Interleukin 1β and Tumor Necrosis Factor α

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    Interleukin-1β and Tumor Necrosis Factor α play related, but distinct, roles in immunity and disease. Our study revealed major mechanistic distinctions in the Toll-like receptor (TLR) signaling-dependent induction for the rapidly expressed genes (IL1B and TNF) coding for these two cytokines. Prior to induction, TNF exhibited pre-bound TATA Binding Protein (TBP) and paused RNA Polymerase II (Pol II), hallmarks of poised immediate-early (IE) genes. In contrast, unstimulated IL1B displayed very low levels of both TBP and paused Pol II, requiring the lineage-specific Spi-1/PU.1 (Spi1) transcription factor as an anchor for induction-dependent interaction with two TLR-activated transcription factors, C/EBPβ and NF-κB. Activation and DNA binding of these two pre-expressed factors resulted in de novo recruitment of TBP and Pol II to IL1B in concert with a permissive state for elongation mediated by the recruitment of elongation factor P-TEFb. This Spi1-dependent mechanism for IL1B transcription, which is unique for a rapidly-induced/poised IE gene, was more dependent upon P-TEFb than was the case for the TNF gene. Furthermore, the dependence on phosphoinositide 3-kinase for P-TEFb recruitment to IL1B paralleled a greater sensitivity to the metabolic state of the cell and a lower sensitivity to the phenomenon of endotoxin tolerance than was evident for TNF. Such differences in induction mechanisms argue against the prevailing paradigm that all IE genes possess paused Pol II and may further delineate the specific roles played by each of these rapidly expressed immune modulators. © 2013 Adamik et al

    The Effect of Unsuccessful Past Repurchases on Future Repurchasing Decisions

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    We find that managers are less likely to repurchase stocks when they lose money on past stock repurchases but find no robust evidence that past gains on repurchases influence future repurchasing activity. This asymmetric sensitivity is strongest for young CEOs and those with the shortest tenure. Also, future repurchases are more sensitive to past repurchase losses for CEOs whose previous lifetime experience with the stock market is unfavorable. The sensitivity of future repurchases to past losses costs firms, on average, about 3.7% per year. When this cost is decomposed into systematic and idiosyncratic components, we find that nearly half (1.8%) comes from mistiming idiosyncratic shocks. Past losses on repurchases have a significant and negative impact on the CEO’s future bonus and increase the likelihood that future CEO termination is involuntary. We also find that negative outcomes from past repurchases encourage the subsequent use of dividends. Our findings suggest that outcomes of past repurchases have economically significant consequences through both nonbehavioral (career concerns) and behavioral (snakebite effect) factors. Includes supplemental appendix

    The Pattern in Securitization and Executive Compensation: Evidence and Regulatory Implications

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    The Dodd-Frank financial reforms of 2010 promised to better align risk-reward incentives by, among other things, reducing imprudent securitzation (i.e., sales of financial assets) and excessive executive compensation. This would, in turn, promote systemic stability. To assess whether Dodd-Frank’s elaborate rules on securitization and compensation are likely to achieve this goal, we explore the connection between the two empirically. Using a unique dataset covering 1993-2009 — the largest of its kind — we find that securitizing banks (regulated depositaries) on average paid their CEOs twice as much as non-securitizing banks, a finding that is both statistically and economically significant. By contrast, non-bank (industrial) firms that securitized actually paid their CEOs less than non-securitizers. Because securitizing banks performed no better than other firms (non-securitizing banks or industrials), we find evidence of agency cost; because bank-originated securitizations performed especially poorly in the financial crisis, we find evidence of social cost. Our findings have important implications for Dodd-Frank, because its rules on securitization and compensation fail to account for the incentive effects of securitization by banks. Its compensation provisions are disconnected from controls on securitization, in particular its risk-retention (“skin in the game”) rules. Moreover, it focuses not on those who “originate” securitizations, such as the banks we study, but instead the “securitizers” who issue securities backed by the financial assets in question. Because banks originated many of the worst securitizations — and yet paid their CEOs more for doing so — Dodd-Frank may be aimed at the wrong segment of securitization. Simpler, better-tailored regulation that accounts for the pattern we observe would more likely achieve Dodd-Frank’s goals of systemic stability and accountability.Temple University. James E. Beasley School of La

    Natural occurrence of Cucumber mosaic virus infecting water mint (Mentha aquatica) in Antalya and Konya, Turkey

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    A virus causing a disease in mint (the aromatic and culinary plant) has recently become a problem in the Taurus Mountains, a mountain range in the Mediterranean region of Turkey. To detect the virus and investigate its distribution in the region, mint leaf samples were collected from the vicinity of spring areas in the plateaus of Antalya and Konya in 2009. It was found that Cucumber mosaic virus (CMV) was detected in 27.08% of symptomatic samples tested by DAS-ELISA. To the best of our knowledge, this is the first report of CMV on mint plants in this region of Turkey
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