b-tagging in DELPHI at LEP

Abstract: The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly

Secondary structure predictions of six miRNA candidates in <i>P. infestans</i>.

<p>Precursor miRNA sequences were folded with the RNAfold program. The miRNA sequences are shown in red.</p

Northern hybridizations detecting <i>P. infestans</i> antisense sRNAs derived from transposons, RxLR and CRN effector genes in R0 and 3928A isolates.

<p><b>A</b>. sRNAs hybridizing to <i>Copia3-LTR</i>, <i>PITG_22969</i> (CRN), <i>Crypton6</i>, <i>PiAvrblb1</i> (RxLR) were detected. Loading controls (U4 spliceosomal RNA) are shown below each autoradiograph. <b>B</b>. Determination of 5′ terminal modifications to sRNAs. From left, terminator exonuclease (TE) and tobacco acid pyrophosphatase (TAP) treatment of 21 and 32 nt sRNAs from <i>Copia 3-LTR</i> and <i>Crypton6</i>, respectively in isolate R0. <b>C</b>. ß-elimination assay for 3′ modifications to sRNAs, determined for 21 nt sRNAs for <i>Copia3-LTR</i> in isolate R0. Lane +β is after treatment with periodate, showing a 1 nt downward shift in size compared to the untreated sample (−β).</p

Size distribution and 5′ nucleotide preferences of sRNAs mapped to transposons, RxLR and CRN effector gene subsets in <i>P. infestans</i> isolates R0 and 3928A.

<p>Abundance of each size class of sRNAs based on nucleotide (nt) length in: <b>A</b>. Transposons <b>B</b>. RxLRs and <b>C</b>. CRNs. The relative frequency of each 5′ terminal nucleotide of sRNAs aligned to: <b>D</b>. Transposons <b>E</b>. RxLRs and <b>F</b>. CRNs.</p

Proposed model for sRNA pathways in <i>P. infestans</i>.

<p><b>A</b>. siRNA pathway. Transcription of repeat regions or transposons, heterochromatic regions or natural antisense transcripts and exogenous dsRNAs will lead to formation of long precursor dsRNAs. PiDcl1 processes these dsRNA into predominantly 21 nt siRNAs, in some instances in association with PiRnh5 (Dicer-like helicase). The 21 nt siRNAs generated by PiDcl1 associate with one of the PiAgo proteins, leading to degradation of target mRNAs. <b>B</b>. Long siRNA (lsiRNA) pathway. lsiRNAs are generated by PiAgo4 and 5 from transposons, coding genes, or overlapping regions of antisense transcription, or dsRNA generated by RNA polymerases. This may be a PiDcl1 independent pathway. Both pathways could be linked via one of the AGOs to heterochromatin formation aided by histone deacetylases and chromodomain proteins. RdR could further amplify the silencing.</p

DCL-dependent generation of 21 nt sRNAs, and AGO involvement in 32 nt sRNA generation.

<p><b>A</b>. <i>Copia3-LTR</i> 21 nt sRNAs in <i>PiDcl1</i> (D1t7, D1t8) and <i>PiRnh5</i> (D2t1) silenced lines. An upward mobility shift to approximately 24/25 nt was observed for the most silenced <i>PiDcl1</i> line, D1t8. <b>B</b>. <i>PITG_22969</i> (CRN) 21 nt sRNAs are abolished upon silencing of <i>PiDcl1</i> (D1t7, D1t8) or <i>PiRnh5</i> (D2t1). <b>C</b>. <i>Crypton6</i> 32 nt sRNAs in <i>PiDcl1</i> (D1t7, D1t8) and <i>PiRnh5</i> (D2t1) silenced lines. Silencing of these genes had no effect on the accumulation of 32 nt sRNAs. <b>D</b>. <i>PiAvrblb1</i> 32 nt sRNAs in <i>PiDcl1</i> (D1t7, D1t8) and <i>PiRnh5</i> (D2t1) silenced lines. Silencing of these genes had no effect on the accumulation of 32 nt sRNAs. <b>E</b> and <b>F</b>. <i>PiAvrblb1</i> 32 nt sRNAs in <i>PiAgo1</i>, <i>4</i>, or <i>5</i> (A1b, A4a, A5c) silenced lines. The accumulation of 32 nt sRNAs is strongly reduced in <i>PiAgo4</i> or <i>5</i> lines, while over-accumulation occurs for <i>PiAgo1</i>. Silenced lines used were <i>PiDcl1</i> (Dicer-like; D1t8, t7), <i>PiRnh5</i> (Dicer-like helicase; D2t1), <i>PiAgo1</i> (Argonaute 1; A1b) <i>PiAgo4</i> (Argonaute 4; A4a), and <i>PiAgo5</i> (Argonaute 5; A5c). Loading controls (U4 spliceosomal RNA) are shown below each autoradiograph.</p

Relative transcript abundance (qRT-PCR) of RxLR and CRN effector genes at different infection time points in <i>P. infestans</i> isolates R0 and 3928A.

<p><b>A</b>. <i>PiAvr3a</i>, <b>B</b>. <i>PiAvr1</i>, <b>C</b>. <i>PiAvrblb1</i>, <b>D</b>. <i>PiAvrblb2</i>, <b>E</b>. <i>PITG_06308</i>, <b>F</b>. <i>PiAvr3b</i>, <b>G</b>. <i>PiAvr4</i>, <b>H</b>. <i>PITG_23226, </i><b>I</b>. <i>PITG_14783</i>, <b>J</b>. <i>PITG_22969</i>. A–I encode RxLR effectors; J encodes a CRN effector. The transcript profiles are shown at 24, 48 and 72 h post-inoculation of potato cultivar Bintje (no known resistance genes) relative to the mRNA level in cultured non-sporulating mycelium (M). In each graph, the light grey bar represents R0, and the dark bar represents 3928A. All calculations and statistical analyses were carried out as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051399#pone.0051399-Avrova2" target="_blank">[90]</a>. Error bars represent confidence intervals calculated using three technical replicates for each sample within the qRT-PCR assay. The abundance of mRNA for each gene is shown as a proportion of the <i>actin A</i> (<i>PiactA</i>) transcript on the y-axis of each graph. Amplifications repeated on independent occasions with different starting RNA and cDNA samples resulted in similar transcript accumulation profiles for all genes tested.</p

Measurement of the triple gluon vertex from four - jet events at LEP

From the combined data of 1990 and 1991 of the DELPHI experiment at LEP, 13057 4-jet events are obtained and used for determining the contribution of the triple-gluon vertex. The relevant variables are the generalized Nachtmann Reiter angle θNR * and the opening angle of the two least energetic jets. A fit to their two-dimensional distribution yields {Mathematical expression} where CA/CF is the ratio of the coupling strength of the triple-gluon vertex to that of gluon bremsstrahlung from quarks, and NC/NA, the ratio of the number of quark colours to the number of gluons. This constitutes a convincing model-independent proof of the existence of the triple-gluon vertex, since its contribution is directly proportional to CA/CF. The results are in agreement with the values expected from QCD:CA/CF=2.25, and NC/NA=3/8. © 1993 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe