Paleomagnetic dating of non-sulfide Zn-Pb ores in SW Sardinia (Italy): a first attempt

A first paleomagnetic investigation aimed at constraining the age of the non-sulfide Zn-Pb ore deposits in the Iglesiente district (SW Sardinia, Italy) was carried out. In these ores, the oxidation of primary sulfides, hosted in Cambrian carbonate rocks, was related to several paleoweathering episodes spanning from the Mesozoic onward. Paleomagnetic analyses were performed on 43 cores from 4 different localities, containing: a) non-oxidized primary sulfides and host rock, b) oxidized Fe-rich hydrothermal dolomites and (c) supergene oxidation ore («Calamine»). Reliable data were obtained from 18 samples; the others show uninterpretable results due to low magnetic intensity or to scattered demagnetization trajectories. Three of them show a scattered Characteristic Remanent Magnetization (ChRM), likely carried by the original (i.e. Paleozoic) magnetic iron sulfides. The remaining 15 samples show a well defined and coherent ChRM, carried by high-coercivity minerals, acquired after the last phase of counterclockwise rotation of Sardinia (that is after 16 Myr), in a time interval long enough to span at least one reversal of the geomagnetic field. Hematite is the main magnetic carrier in the limestone, whereas weathered hydrothermal dolomite contains goethite or a mixture of both. The results suggest that paleomagnetism can be used to constrain the timing of oxidation in supergene-enriched ores

Engineered Proteins in Materials Research

Peptides and proteins have attracted scientific and technological interest largely because of their intriguing properties as catalysts, receptors, signalling molecules, and therapeutic agents. In attempts to understand and exploit these properties, protein engineering has been used primarily to obtain precious proteins in increased quantities, or to explore systematic alterations in protein sequence through site-directed mutagenesis. Design of protein structures de novo ("from scratch") has attracted less attention, and has been directed in the main toward studies of protein folding (Kamtekar et al., 1993). Such studies represent a key element in the current vigorous investigation of the connections between amino acid sequence and the three-dimensional structures of isolated protein chains in aqueous solution. This chapter describes protein engineering of quite another sort, in which the proteinacious nature of the product is less important than its macromolecular character

Environmental Predictors of Human West Nile Virus Infections, Colorado

To determine whether environmental surveillance of West Nile virus–positive dead birds, mosquito pools, equines, and sentinel chickens helped predict human cases in metropolitan Denver, Colorado, during 2003, we analyzed human surveillance data and environmental data. Birds successfully predicted the highest proportion of human cases, followed by mosquito pools, and equines

Infection and Transmission of Rift Valley Fever Viruses Lacking the NSs and/or NSm Genes in Mosquitoes: Potential Role for NSm in Mosquito Infection

Rift Valley fever virus is transmitted mainly by mosquitoes and causes disease in humans and animals throughout Africa and the Arabian Peninsula. The impact of disease is large in terms of human illness and mortality, and economic impact on the livestock industry. For these reasons, and because there is a risk of this virus spreading to Europe and North America, it is important to develop a vaccine that is stable, safe and effective in preventing infection. Potential vaccine viruses have been developed through deletion of two genes (NSs and NSm) affecting virus virulence. Because this virus is normally transmitted by mosquitoes we must determine the effects of the deletions in these vaccine viruses on their ability to infect and be transmitted by mosquitoes. An optimal vaccine virus would not infect or be transmitted. The viruses were tested in two mosquito species: Aedes aegypti and Culex quinquefasciatus. Deletion of the NSm gene reduced infection of Ae. aegypti mosquitoes indicating a role for the NSm protein in mosquito infection. The virus with deletion of both NSs and NSm genes was the best vaccine candidate since it did not infect Ae. aegypti and showed reduced infection and transmission rates in Cx. quinquefasciatus

Isolation and genomic characterization of Chaoyang virus strain ROK144 from \u3ci\u3eAedes vexansnipponii\u3c/i\u3e from the Republic of Korea

During June 2003, mosquito surveillance was conducted at a US Army installation and a US Military training site 2 km south of the demilitarized zone, Republic of Korea. Mosquitoes were collected using Mosquito MagnetsTM, sorted to species, and assayed for the presence of arboviruses. From the 3,149 mosquitoes that were sorted into126 pools, one Aedes vexan snipponii pool (out of 73 pools) tested positive for flavivirus RNA by reverse transcription-PCR. After isolation from C6/36 cell culture supernatant, the viral genome was sequenced and found to be 98.9% related to Chaoyang virus, a potential arthropod-specific flavivirus. This report details the first identification of Chaoyang virus in the Republic of Korea and highlights its relationship to other flaviviruses

Isolation and genomic characterization of Chaoyang virus strain ROK144 from \u3ci\u3eAedes vexansnipponii\u3c/i\u3e from the Republic of Korea

During June 2003, mosquito surveillance was conducted at a US Army installation and a US Military training site 2 km south of the demilitarized zone, Republic of Korea. Mosquitoes were collected using Mosquito MagnetsTM, sorted to species, and assayed for the presence of arboviruses. From the 3,149 mosquitoes that were sorted into126 pools, one Aedes vexan snipponii pool (out of 73 pools) tested positive for flavivirus RNA by reverse transcription-PCR. After isolation from C6/36 cell culture supernatant, the viral genome was sequenced and found to be 98.9% related to Chaoyang virus, a potential arthropod-specific flavivirus. This report details the first identification of Chaoyang virus in the Republic of Korea and highlights its relationship to other flaviviruses

Using portable X-Ray fluorescence to identify the K-Pg boundary in terrestrial records

Peer Reviewe

A hierarchical network approach for modeling Rift Valley fever epidemics with applications in North America

Rift Valley fever is a vector-borne zoonotic disease which causes high morbidity and mortality in livestock. In the event Rift Valley fever virus is introduced to the United States or other non-endemic areas, understanding the potential patterns of spread and the areas at risk based on disease vectors and hosts will be vital for developing mitigation strategies. Presented here is a general network-based mathematical model of Rift Valley fever. Given a lack of empirical data on disease vector species and their vector competence, this discrete time epidemic model uses stochastic parameters following several PERT distributions to model the dynamic interactions between hosts and likely North American mosquito vectors in dispersed geographic areas. Spatial effects and climate factors are also addressed in the model. The model is applied to a large directed asymmetric network of 3,621 nodes based on actual farms to examine a hypothetical introduction to some counties of Texas, an important ranching area in the United States of America (U.S.A.). The nodes of the networks represent livestock farms, livestock markets, and feedlots, and the links represent cattle movements and mosquito diffusion between different nodes. Cattle and mosquito (Aedes and Culex) populations are treated with different contact networks to assess virus propagation. Rift Valley fever virus spread is assessed under various initial infection conditions (infected mosquito eggs, adults or cattle). A surprising trend is fewer initial infectious organisms result in a longer delay before a larger and more prolonged outbreak. The delay is likely caused by a lack of herd immunity while the infections expands geographically before becoming an epidemic involving many dispersed farms and animals almost simultaneously

Natural Enzootic Vectors of Venezuelan equine encephalitis virus in the Magdalena Valley, Colombia

To characterize the transmission cycle of enzootic Venezuelan equine encephalitis virus (VEEV) strains believed to represent an epizootic progenitor, we identified natural vectors in a sylvatic focus in the middle Magdalena Valley of Colombia. Hamster-baited traps were placed into an active forest focus, and mosquitoes collected from each trap in which a hamster became infected were sorted by species and assayed for virus. In 18 cases, a single, initial, high-titered mosquito pool representing the vector species was identified. These vectors included Culex (Melanoconion) vomerifer (11 transmission events), Cx. (Mel.) pedroi (5 transmissions) and Cx. (Mel.) adamesi (2 transmissions). These results extend the number of proven enzootic VEEV vectors to 7, all of which are members of the Spissipes section of the subgenus Melanoconion. Our findings contrast with previous studies, which have indicated that a single species usually serves as the principal enzootic VEEV vector at a given location