Seasonal variations in antibiotic resistance gene transport in the Almendares River, Havana, Cuba

Numerous studies have quantified antibiotic resistance genes (ARG) in rivers and streams around the world, and significant relationships have been shown that relate different pollutant outputs and increased local ARG levels. However, most studies have not considered ambient flow conditions, which can vary dramatically especially in tropical countries. Here, ARG were quantified in water column and sediment samples during the dry- and wet-seasons to assess how seasonal and other factors influence ARG transport down the Almendares River (Havana, Cuba). Eight locations were sampled and stream flow estimated during both seasons; qPCR was used to quantify four tetracycline, two erythromycin, and three beta-lactam resistance genes. ARG concentrations were higher in wet-season versus dry-season samples, which combined with higher flows, indicated much greater ARG transport downstream during the wet-season. However, water column ARG levels were more spatially variable in the dry-season than the wet-season, with the proximity of waste outfalls strongly influencing local ARG levels. Results confirm that dry-season sampling provides a useful picture of the impact of individual waste inputs on local stream ARG levels, whereas the majority of ARGs in this tropical river were transported downstream during the wet-season, possibly due to re-entrainment of ARG from sediments

Cases and Controversies: Some Things to Do with Contracts Cases,

As a co-author of one of the two dozen or more currently-in-print Contracts casebooks, I obviously have both a point of view about, and a personal stake in, the survival of this particular method of instruction. Whether the legal casebook—or any other book, in the form of bound sheets of paper—will remain a part of our academic culture much longer is clearly up for grabs, however. Electronic records have so many advantages over the printed page that, at least for many purposes, they will surely become the dominant form of preserving, retrieving, and transmitting information, if indeed they are not already. But through whatever medium, I hope that legal training will continue to retain the study of “cases” as an important component of a legal education. In this brief discussion I will ruminate a little about the various ways in which case study can contribute to law study—or at least to the study of contract law, the area with which I am most familiar