!Cuba! river water chemistry reveals rapid chemical weathering, the echo of uplift, and the promise of more sustainable agriculture

For the first time in more than half a century, a joint Cuban/American science team has worked together to quantify the impacts of chemical weathering and sustainable agriculture on river water quality in Cuba - the largest and most populous Caribbean island. Such data are critical as the world strives to meet sustainable development goals and for understanding rates of landscape change in the tropics, an understudied region. To characterize the landscape, we collected and analyzed water samples from 25 rivers in central Cuba where upstream land use varies from forested to agricultural. Cuban river waters bear the fingerprint of the diverse rock types underlying the island, and many carry exceptionally high dissolved loads. Chemical denudation rates are mostly among the top 25% globally and are similar to those measured in other Caribbean islands. High rates of solute export and the distinct composition of the waters in specific basins suggest flow paths that bring river source waters into contact with fresh, weatherable rock - unusual in a warm, wet, tropical climate where weathering should extend deep below the surface. Tectonically driven uplift likely maintains the supply of weatherable material, leading to channel incision and, thus, to the exposure of bedrock in many river channels. Despite centuries of agriculture, the impact on these rivers\u27 biogeochemistry is limited. Although river water in many central Cuban rivers has high levels of E. coli bacteria, likely sourced from livestock, concentrations of dissolved nitrogen are far lower than other areas where intensive agriculture is practiced, such as the Mississippi River Basin. This suggests the benefits of Cuba\u27s shift to conservation agriculture after 1990 and provides a model for more sustainable agriculture worldwide

Specific Inhibition of Bovine Viral Diarrhea Virus Replicase

Compound-1453 was identified and characterized as a specific inhibitor of bovine viral diarrhea virus (BVDV). The concentration of compound-1453 which results in 50% protection from virus-induced cytopathic effect is ∼2.2 μM, with a therapeutic index of 60, and it is not active against a panel of RNA and DNA viruses. A time-of-addition experiment suggested that compound-1453 targets a stage of the viral life cycle after viral entry. To determine the target of compound-1453, resistant virus was generated. Resistant variants grew efficiently in the presence or absence of 33 μM compound-1453 and exhibited replication efficiency in the presence of compound-1453 approximately 1,000-fold higher than that of the wild-type (wt) virus. Functional mapping and sequence analysis of resistant cDNAs revealed a single amino acid substitution (Glu to Gly) at residue 291 in the NS5B polymerase in all eight independently generated cDNA clones. Recombinant virus containing this single mutation retained the resistance phenotype and a replication efficiency similar to that of the original isolated resistant virus. Since compound-1453 did not inhibit BVDV polymerase activity in vitro (50% inhibitory concentration > 300 μM), we developed a membrane-based assay that consisted of a BVDV RNA replicase complex isolated from virus-infected cells. Compound-1453 inhibited the activity of the wt, but not the drug-resistant, replicase in the membrane assay at concentrations similar to those observed in the viral infection assay. This work presents a novel inhibitor of a viral RNA-dependent RNA replicase