Changes in benthic nutrient sources within a wetland after hydrologic reconnection.

Removing dams and levees to restore hydrologic connectivity and enhance ecosystem services such as nutrient removal has been an increasingly common management practice. In the present study, the authors assessed geochemical and biological changes following engineered levee breaches that reconnected eutrophic Upper Klamath Lake and Agency Lake, Oregon, USA, to an adjacent, historic wetland that had been under agricultural use for the last seven decades. Over the three-year study, the reconnected wetland served as a benthic source for both macronutrients (dissolved organic carbon [DOC], soluble reactive phosphorus [SRP], and ammonia) and micronutrients (dissolved iron and manganese). The magnitude of those benthic sources was similar to or greater than that of allochthonous sources. The highest DOC benthic flux to the water column occurred immediately after rewetting occurred. It then decreased during the present study to levels more similar to the adjacent lake. Dissolved ammonia fluxes, initially negative after the levee breaches, became consistently positive through the remainder of the study. Nitrate fluxes, also initially negative, became negligible two years after the levee breaches. In contrast to previous laboratory studies, SRP fluxes remained positive, as did fluxes of dissolved iron and manganese. Our results indicate that the timescales of chemical changes following hydrologic reconnection of wetlands are solute-specific and in some cases extend for multiple years beyond the reconnection event. During the present study, colonization of the reconnected wetlands by aquatic benthic invertebrates gradually generated assemblages similar to those in a nearby wetland refuge and provided further evidence of the multiyear transition of this area to permanent aquatic habitat. Such timescales should be considered when developing water-quality management strategies to achieve wetland-restoration goals.

Inhibition of PKR by RNA and DNA viruses.

Interferons were the first of the anti-viral innate immune modulators to be characterized, initially characterized solely as anti-viral proteins [reviewed in Le Page, C., Genin, P., Baines, M.G., Hiscott, J., 2000. Inteferon activation and innate immunity. Rev. Immunogenet. 2, 374-386]. As we have progressed in our understanding of the interferons they have taken a more central role in our understanding of innate immunity and its interplay with the adaptive immune response. One of the key players in function of interferon is the interferon-inducible enzyme, protein kinase (PKR, activatable by RNA). The key role played by PKR in the innate response to virus infection is emphasized by the large number of viruses, DNA viruses as well as RNA viruses, whose hosts range from insects to humans, that code for PKR inhibitors. In this review we will first describe activation of PKR and then describe the myriad of ways that viruses inhibit function of PKR.

The N-terminal domain of the vaccinia virus E3L-protein is required for neurovirulence, but not induction of a protective immune response.

Encephalitis is a rare, but serious complication from vaccination against smallpox using replication competent strains of vaccinia virus. In this report we describe mutants of vaccinia virus, containing N-terminal deletions of the vaccinia virus interferon resistance gene, E3L, that are attenuated for neuropathogenesis in a mouse model system. These recombinant viruses replicated to high titers in the nasal mucosa after intra-nasal infection of C57BL/6 mice but failed to spread to the lungs or brain. These viruses demonstrated reduced pathogenicity after intra-cranial infection as well, indicating a decrease in neurovirulence. Intra-nasal inoculation or inoculation by scarification with a low dose of recombinant virus containing a deletion of the entire N-terminal domain of E3L protected against challenge with a high dose of wild-type vaccinia virus, suggesting that this replication competent, but attenuated strain of vaccinia virus may have promise as an improved vaccine for protecting against smallpox, and as a vector for inducing mucosal immunity to heterologous pathogenic organisms.