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NCAA student-athletes are at risk for various physical (e.g. injury), psychosocial (e.g. depression), and spiritual (e.g. identity development) health concerns. Consequently, researchers and NCAA a...

We present modern B/Ca core-top calibrations for the epifaunal benthic foraminifer Nuttallides umbonifera and the infaunal Oridorsalis umbonatu s to test whether B/Ca values in these species can be used for the reconstruction of paleo-Δ[CO 3 2− ]. O. umbonatus originated in the Late Cretaceous and remains extant , whereas N. umbonifera originated in the Eocene and is the closest extant relative to Nuttallides truempyi , which ranges from the Late Cretaceous through the Eocene. We measured B/Ca in both species in 35 Holocene sediment samples from the Atlantic, Pacific and Southern Oceans. B/Ca values in epifaunal N. umbonifera (~ 85–175 μmol/mol) are consistently lower than values reported for epifaunal Cibicidoides (Cibicides) wuellerstorfi (130–250 μmol/mol), though the sensitivity of Δ[CO 3 2− ] on B/Ca in N. umbonifera (1.23 ± 0.15) is similar to that in C. wuellerstorfi (1.14 ± 0.048). In addition, we show that B/Ca values of paired N. umbonifera and its extinct ancestor, N. truempyi, from Eocene cores are indistinguishable within error. In contrast, both the B/Ca (35–85 μmol/mol) and sensitivity to Δ[CO 3 2− ] (0.29 ± 0.20) of core-top O. umbonatus are considerably lower (as in other infaunal species), and this offset extends into the Paleocene. Thus the B/Ca of N. umbonifera and its ancestor can be used to reconstruct bottom water Δ[CO 3 2− ], whereas O. umbonatus B/Ca appears to be buffered by porewater [CO 3 2− ] and suited for constraining long-term drift in seawater B/Ca.

Knowledge of how ribonucleic acid (RNA) structures fold to form intricate, three-dimensional structures has provided fundamental insights into understanding the biological functions of RNA. Nuclear magnetic resonance (NMR) spectroscopy is a particularly useful high-resolution technique to investigate the dynamic structure of RNA. Effective study of RNA by NMR requires enrichment with isotopes of (13)C or (15)N or both. Here, we present a method to produce milligram quantities of uniformly (15)N- and site-specifically (13)C-labeled RNAs using wild-type K12 and mutant tktA Escherichia coli in combination with a tRNA-scaffold approach. The method includes a double selection protocol to obtain an E. coli clone with consistently high expression of the recombinant tRNA-scaffold. We also present protocols for the purification of the tRNA-scaffold from a total cellular RNA extract and the excision of the RNA of interest from the tRNA-scaffold using DNAzymes. Finally, we showcase NMR applications to demonstrate the benefit of using in vivo site-specifically (13)C-labeled RNA.

In the last two decades, RNA has emerged as more than a messenger molecule. RNA has numerous functions, including enzymatic activity and regulation of gene expression. Critical gene expression in numerous pathogenic bacteria is controlled by riboswitches, folded RNA structures located in the untranslated regions of mRNAs. Riboswitches have folded aptamer domains that change shape upon metabolite binding to modulate the transcription or translation of the downstream mRNA. The exploitation of riboswitches as potential therapeutic targets requires a detailed understanding of their three-dimensional architecture and dynamics.Nuclear Magnetic Resonance (NMR) spectroscopy is an attractive method of studying RNA structure and dynamics in solution, without worrying about crystallization. However, two disadvantages of NMR must be overcome, especially when studying molecules of large molecular weight: spectral overlap of resonances and broadened linewidths. Furthermore, common methods of RNA purification involve denaturation and renaturation of the RNA, leading to misfolded RNAs in the sample.The resolution and sensitivity of NMR spectra can be significantly improved by the site-specific labeling of RNA with NMR-active isotopes, 15N and 13C. Using genetically engineered E. coli mutants, we have developed a method for large-scale, in vivo production of site-specifically labeled RNA. To prevent the RNA from being degraded by nucleases in the cell before it can be harvested, our construct includes a tRNA scaffold that disguises the RNA of interest. Our purification protocol excludes commonly-used denaturation steps, allowing the RNA to maintain its co-transcriptional fold. We will showcase our efforts to streamline in vivo labeling for selected riboswitches. Our long-term goal is to determine how these riboswitches change from an unfolded structure to one with the ability to recognize their cognate metabolites.