The Investigation of DNA and RNA Structural Differences Using Ultra High Performance Liquid Chromatography

DNA and RNA chromatography is extensively used for nucleic acid analysis. To better understand the chromatographic mechanisms by which DNA and RNA oligonucleotides are separated, ion pair reverse-pair ultra-high performance liquid chromatography (IP RP UHPLC) methods were developed. 11mer and 12mer DNA and RNA oligonucleotides of various compositions were used during this study. The first part of this study analyzed 11mer DNA and RNA oligonucleotides to better understand the chromatographic separations of DNA and RNA. The results gathered through the IP RP UHPLC analysis of these oligonucleotides demonstrated the existence of structural features that affect the chromatographic separations of DNA and RNA. This led to the IP RP UHPLC analysis of DNA and RNA oligonucleotides, of equal length and sequence, which either formed a 4 base-pair or 2 base-pair tetraloop secondary structure. The purpose of this investigation is to improve the isolation and purification of nucleic acid mixtures by understanding how DNA and RNA oligonucleotides interact with the stationary support but to also illuminate the role of structural features in nucleic acid separations. The characterization and the separation of the DNA and RNA oligonucleotides were achieved through a variety of methods including temperature melting experiments. The results gathered demonstrated the effectiveness of IP RP UHPLC to analyze the differences between DNA and RNA oligonucleotide separations. The DNA oligonucleotides eluted earlier than the RNA oligonucleotides which demonstrated that RNA has a different chromatographic mechanism than DNA. Differences between nucleic acid separations of fragments with the 2 base-pair tetraloop and 4 base-pair tetraloop structural modifications were also observed. The oligonucleotides with the 4 base-pair tetraloop eluted later than the oligonucleotides with the 2 base-pair tetraloop demonstrating the influence of structural modifications on the separation mechanisms of nucleic acids. The temperature melting experiments performed also confirmed that structural modifications influence the interaction between nucleic acids and stationary support. These results demonstrate the effectiveness of IP RP UHPLC to observe structural differences between DNA and RNA and as an alternative method to traditional methods, such as gel electrophoresis, to analyze oligonucleotides

Novel RNA modifications in the nervous system: form and function

Modified RNA molecules have recently been shown to regulate nervous system functions. This mini-review and associated mini-symposium provide an overview of the types and known functions of novel modified RNAs in the nervous system, including covalently modified RNAs, edited RNAs, and circular RNAs. We discuss basic molecular mechanisms involving RNA modifications as well as the impact of modified RNAs and their regulation on neuronal processes and disorders, including neural fate specification, intellectual disability, neurodegeneration, dopamine neuron function, and substance use disorders

The profile and dynamics of RNA modifications in animals

More than a hundred distinct modified nucleosides have been identified in RNA, but little is known about their distribution across different organisms, dynamic nature and their response to cellular and environmental stress. Mass spectrometry based methods have been at the forefront of identifying and quantifying modified nucleosides. However, they often require synthetic reference standards, which do not exist for many modified nucleosides and therefore impedes their analysis. Here, we use a metabolic labeling approach to rapidly generate bio-isotopologues of the complete C. elegans transcriptome and its modifications, and use them as reference standards to characterize the RNA modification profile in this multicellular organism via an untargeted liquid-chromatography tandem high-resolution mass spectrometry (LC-MS/HRMS) approach. We furthermore show that several of these RNA modifications have a dynamic response to environmental stress and that in particular changes in the tRNA wobble base modification 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) lead to codon biased gene expression changes in starved animals.CRUK Wellcome Trus

A lexicon of DNA modifications: their roles in embryo development and the germline

5-methylcytosine (5mC) on CpG dinucleotides has been viewed as the major epigenetic modification in eukaryotes for a long time. Apart from 5mC, additional DNA modifications have been discovered in eukaryotic genomes. Many of these modifications are thought to be solely associated with DNA damage. However, growing evidence indicates that some base modifications, namely 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), 5-carboxylcytosine (5caC), and N6-methadenine (6mA), may be of biological relevance, particularly during early stages of embryo development. Although abundance of these DNA modifications in eukaryotic genomes can be low, there are suggestions that they cooperate with other epigenetic markers to affect DNA-protein interactions, gene expression, defense of genome stability and epigenetic inheritance. Little is still known about their distribution in different tissues and their functions during key stages of the animal lifecycle. This review discusses current knowledge and future perspectives of these novel DNA modifications in the mammalian genome with a focus on their dynamic distribution during early embryonic development and their potential function in epigenetic inheritance through the germ line

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV

The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe