Beginning to Understand the End of the Chromosome

In their 1985 Cell paper, Greider and Blackburn announced the discovery of an enzyme that extended the DNA at chromosome telomeres in the ciliate, Tetrahymena. Since then, there has been an explosion of knowledge about both the RNA and protein subunits of this unusual ribonucleoprotein enzyme in organisms ranging from the ciliates to yeast to humans. The regulation of telomerase is now understood to take place both at the level of synthesis of the enzyme and via the state of its substrate, the telomere itself. The roles of telomerase in both cellular immortality and cancer are vibrant areas of current research

Pot1, the Putative Telomere End-binding Protein in Fission Yeast and Humans

Telomere proteins from ciliated protozoa bind to the single-stranded G-rich DNA extensions at the ends of macronuclear chromosomes. We have now identified homologous proteins in fission yeast and in humans. These Pot1 (protection oftelomeres) proteins each bind the G-rich strand of their own telomeric repeat sequence, consistent with a direct role in protecting chromosome ends. Deletion of the fission yeastpot1 +gene has an immediate effect on chromosome stability, causing rapid loss of telomeric DNA and chromosome circularization. It now appears that the protein that caps the ends of chromosomes is widely dispersed throughout the eukaryotic kingdom

Engineering Disulfide Cross‐Links in RNA Using Thiol‐Disulfide Interchange Chemistry

Protocols for postsynthetic modification of 2‐amino‐containing oligoribonucleotides with either an alkyl‐phenyl disulfide or an alkyl thiol group are described. These groups react under mild conditions to form disulfide cross‐links by thiol‐disulfide interchange. These reactants do not form a disulfide bond when incorporated on opposite faces of a short continuous RNA helix, but do form disulfide bonds rapidly when they are placed in proximity. In addition, by incorporating these groups at various positions on large RNAs by semisynthesis, the dynamics of thermal motions can be detected. Such motions are believed to be linked to biological function, and the protocols presented in this unit are among the few simple ways to assess such dynamics.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143724/1/cpnc0501.pd

Applying Business Analytic Methods To Improve Organizational Performance In The Public School System

This work applies business analytics techniques to the setting of the public school system to improve educational attainment in both junior high and high school in the United States. In particular, this paper reviews common factors identified in the literature as influencing a student’s success in secondary school, discusses how those factors could be digitized and collected through information systems and theorizes how big data and analytics could be further applied to these organization to manage their performance. We then look at the uses of analytics in schools to see how well they match and identify areas for improvement. This work hopes to show that there has been a large effort to digitize some of the prediction factors; however, a large number of the more readily influenced factors have yet to be digitized and used to make evidence based decisions to improve student outcomes in the public school system

RNase P Branches Out from RNP to Protein: Organelle-Triggered Diversification?

RNase P is the enzyme that removes 5′ leader sequences from precursor tRNAs. Remarkably, in most organisms, RNase P is a ribonucleoprotein particle where the RNA component is responsible for catalysis. In this issue of Genes \u26 Development, Gutmann and colleagues (pp. 1022–1027) report the first organism,Arabidopsis thaliana, to employ protein-only RNase P in both its nucleus and organelles. An intriguing possibility is that replacement of RNase P ribonucleoprotein particles (RNPs) by proteins may have been triggered by the acquisition of organelles

The future of research universities. Is the model of research-intensive universities still valid at the beginning of the twenty-first century?

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Crawling Out of the RNA World

Comparison of phylogenetically diverse ribonucleoprotein (RNP) enzymes and information about their biochemistry have stimulated hypotheses about their evolution. Instead of the canonical view, in which catalysis proceeds from ribozyme to RNP enzyme to protein enzyme, RNP enzymes and proteins are seen to share contemporary catalysis. Furthermore, the RNA components of RNP enzymes show no evidence of fading out but instead, in some cases, have elaborated new functions

Effects of Herbivory, Fire and N2-fixation on Nutrient Limitation in a Humid African Savanna

The quantities and spatial distribution of nutrients in savanna ecosystems are affected by many factors, of which fire, herbivory and symbiotic N2-fixation are particularly important. We measured soil nitrogen (N) pools and the relative abundance of N and phosphorus (P) in herbaceous vegetation in five vegetation types in a humid savanna in Tanzania. We also performed a factorial fertilization experiment to investigate which nutrients most limit herbaceous production. N pools in the top 10cm of soil were low at sites where fires were frequent, and higher in areas with woody legume encroachment, or high herbivore excretion. Biomass production was co-limited by N and P at sites that were frequently burnt or heavily grazed by native herbivores. In contrast, aboveground production was limited by N in areas receiving large amounts of excreta from livestock. N2-fixation by woody legumes did not lead to P-limitation, but did increase the availability of N relative to P. We conclude that the effects of fire, herbivory and N2-fixation upon soil N pools and N:P-stoichiometry in savanna ecosystems are, to a large extent, predictabl

Local RNA Structural Changes Induced by Crystallization are Revealed by SHAPE

We present a simple approach to locate sites that undergo conformational changes upon crystallization by comparative structural mapping of the same RNA in three different environments. As a proof of principle, we probed the readily crystallized P4–P6ΔC209 domain from the Tetrahymena thermophila group I intron in a native solution, in a solution mimicking the crystallization drop, and in crystals. We chose the selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) chemistry, which monitors the flexibility and the conformation of each nucleotide. First, SHAPE successfully revealed the structural changes that occur during the crystallization process. Specifically, 64% of the nucleotides implicated in packing contacts and present in the portion of the molecule analyzed were identified. Second, reactivity differences for some of these nucleotides were already observed in the crystallization solution, suggesting that the crystallization buffer locked down a particular structure that was favorable to crystal formation. Third, the probing of a known structure extends our understanding of the structural basis for the SHAPE reaction by suggesting that reactivity is enhanced by a C2′-endo sugar pucker. Furthermore, by identifying local conformational changes of the RNA that take place during crystallization, SHAPE could be combined with the in vitro selection of stable mutants to rationalize the design of RNA candidates for crystallization