Incorporating LC-MS/MS Analysis and the Dereplication of Natural Product Samples into an Upper-Division Undergraduate Laboratory Course.

Growth in the biomedical and biotechnology sectors requires a highly trained and highly skilled workforce to answer the next great scientific questions. Undergraduate laboratory courses incorporating hands-on training based in authentic research position soon-to-be graduates to learn in environments that mirror that of academic, industrial, and government laboratories. Mass spectrometry is one of the most broadly applied analyses carried out in the biomedical and pharmaceutical sciences and thus it is essential that upper-division students gain hands-on experience in techniques and analytical workflows in mass spectrometry. Our pre-course assessments identified weaknesses in student experience and knowledge in the fundamentals of mass spectrometry, supporting that it was a necessary area for improvement. We incorporated a laboratory experiment focused on tandem mass spectrometry and database searching into a preexisting mini-semester project devoted to identifying metabolites from medicinal plants. Implementation of the experiment allowed students to make more confident metabolite identifications, introduced them to a cutting-edge database analysis platform (GNPS: Global Natural Products Social Molecular Networking), and increased student experience and knowledge of mass spectrometry in addition to the principle of dereplication of samples derived from nature.

Screening the PRISM Library against Staphylococcus aureus Reveals a Sesquiterpene Lactone from Liriodendron tulipifera with Inhibitory Activity.

Infections caused by the bacterium Staphylococcus aureus continue to pose threats to human health and put a financial burden on the healthcare system. The overuse of antibiotics has contributed to mutations leading to the emergence of methicillin-resistant S. aureus, and there is a critical need for the discovery and development of new antibiotics to evade drug-resistant bacteria. Medicinal plants have shown promise as sources of new small-molecule therapeutics with potential uses against pathogenic infections. The principal Rhode Island secondary metabolite (PRISM) library is a botanical extract library generated from specimens in the URI Youngken Medicinal Garden by upper-division undergraduate students. PRISM extracts were screened for activity against strains of methicillin-susceptible S. aureus (MSSA). An extract generated from the tulip tree (Liriodendron tulipifera) demonstrated growth inhibition against MSSA, and a bioassay-guided approach identified a sesquiterpene lactone, laurenobiolide, as the active constituent. Intriguingly, its isomers, tulipinolide and epi-tulipinolide, lacked potent activity against MSSA. Laurenobiolide also proved to be more potent against MSSA than the structurally similar sesquiterpene lactones, costunolide and dehydrocostus lactone. Laurenobiolide was the most abundant in the twig bark of the tulip tree, supporting the twig bark's historical and cultural usage in poultices and teas.

Draft Genome Sequence of Pseudoalteromonas sp. Strain JC3.

We report the draft genome sequence for Pseudoalteromonas sp. strain JC3, an isolate obtained from an aquaculture facility for whiteleg shrimp (Litopenaeus vannamei). The JC3 genome suggests multiple mechanisms for microbial interactions, including a type VI secretion system and potential for antibiotic production.