Beloit College

Ecological interactions between bacteria and nematodes in many environments provide a basis for the prediction that diverse bacteria produce anti-nematode compounds. The discovery of microbial secondary metabolites with broad-spectrum nematostatic or nematicidal properties can be hastened by drug screening approaches that include several nematode species and phenotypes. We cultured a collection of 22 soil-derived bacterial isolates that carry in their genomes putative pathways for production of unknown secondary metabolites. Isolates were cultured in various media to enhance natural product diversity and yield, and we evaluated culture filtrates for activity against two evolutionarily distinct nematode species: Clade V free-living nematode Caenorhabditis elegans and Clade III mammalian parasitic nematodes in the genus Brugia. Partitioned extracts from Pseudomonas sp. strain TE4607 stunted C. elegans development and caused motility defects in both blood-circulating larval and adult stages of Brugia. The primary active compound was identified as labradorin 1, an indole with known antibacterial and anticancer properties that had not been previously described as affecting nematodes. Notably, filtrates of Pseudomonas sp. TE4607 cultures attracted free-living nematodes in sensory assays, adding to evidence that certain Pseudomonas species modulate the behavior of free-living nematodes. These findings underscore the need to further explore the link between nematode sensory responses and whole-organism effects of microbial metabolites, with potential applications in anthelmintic discovery.

Abstract This chapter starts at the cliché of the smart home that has gone rogue and introduces the question of whether these integrated, distributed systems can have ethical frameworks like human ethics that could prevent the science fictional trope of the evil, sentient house. I argue that such smart systems are not a threat on their own, because these kinds of integrated, distributed systems are not the kind of things that could be conscious, a precondition for having ethics like ours (and ethics like ours enable the possibility of being the kinds of things that could be evil). To make these arguments, I look to the history of AI/artificial consciousness and 4e cognition, concluding with the idea that our human ethics as designers and consumers of these systems is the real ethical concern with smart life systems.

Lead chloride has a moderate solubility, allowing small, but quantifiable, amounts to be used in a lab experiment studying solubility. Two gravimetric methods are compared by each student. The first method involves weighing excess lead chloride before and after dissolution. The second method precipitates dissolved lead ion from a saturated solution. The most common error in both methods, not collecting all of the solid, results in high solubility values in the first method and low solubility values in the second. This can lead to rich student discussion and evaluation of these techniques. Using sulfate as the precipitating agent is greener than using chromate as the precipitating agent; similar results are obtained, and the importance of green chemistry can be introduced. To further enrich the chemistry content exploration in this lab experiment, each student measures solubility in a different sodium chloride concentration, leading to observable common ion and complexation effects. This laboratory experiment is done in one 3 h lab period in an analytical chemistry course that has a heavy emphasis on chemical equilibria and is followed up by additional calculations later in the course.