Understanding 16S ribosomal RNA conformational changes during 30S subunit assembly

The purpose of this course of study is to understand the conformational changes that occur in 16S rRNA during ribosomal assembly. The prokaryotic ribosome comprises two asymmetric subunits, the large (50S) and small (30S) subunits. The 30S subunit contains 16S rRNA and the small ribosomal proteins (S1--S21). Functional 30S ribosomal subunits can be reconstituted in vitro from purified components. Reconstitution performed at low temperatures results in a stall in 30S subunit assembly. This stall produces a R&barbelow;econstitution I&barbelow;ntermediate (RI) which sediments at 21S and contains 16S rRNA and a subset of small subunit proteins. In order for RI to be converted into functional 30S subunits, a temperature shift is first required. This shift produces a particle, RI*, with the same composition as RI, yet a dramatically different sedimentation coefficient (26S). RI* can then go on to bind the remaining small subunit proteins, ultimately resulting in functional 30S subunit formation. To better understand the nature of these assembly transitions and thus small subunit assembly, changes in reactivity of each nucleotide during the course of assembly was monitored. The changes in reactivity of nucleotides in 16S rRNA between each of the assembly species (16S, RI, RI* and 30S) were analyzed in the context of the 30S subunit structure and previous biochemical studies to better understand the relationship between ribosomal assembly and function

Understanding research impact

Across the globe, numerous kid-ney transplant candidates and donors are linking up in often complicated ways to facilitate more transplants through exchange pro-grams, or swaps. The largest swap so far, which was orchestrated by the National Kidney Registry (NKR) and involved 60 lives and 30 kid-neys, was described recently in The New York Time

Academic information on Twitter: A user survey

Although counts of tweets citing academic papers are used as an informal indicator of interest, little is known about who tweets academic papers and who uses Twitter to find scholarly information. Without knowing this, it is difficult to draw useful conclusions from a publication being frequently tweeted. This study surveyed 1,912 users that have tweeted journal articles to ask about their scholarly-related Twitter uses. Almost half of the respondents (45%) did not work in academia, despite the sample probably being biased towards academics. Twitter was used most by people with a social science or humanities background. People tend to leverage social ties on Twitter to find information rather than searching for relevant tweets. Twitter is used in academia to acquire and share real-time information and to develop connections with others. Motivations for using Twitter vary by discipline, occupation, and employment sector, but not much by gender. These factors also influence the sharing of different types of academic information. This study provides evidence that Twitter plays a significant role in the discovery of scholarly information and cross-disciplinary knowledge spreading. Most importantly, the large numbers of non-academic users support the claims of those using tweet counts as evidence for the non-academic impacts of scholarly researc