Chicken rRNA Gene Cluster Structure

<div><p>Ribosomal RNA (rRNA) genes, whose activity results in nucleolus formation, constitute an extremely important part of genome. Despite the extensive exploration into avian genomes, no complete description of avian rRNA gene primary structure has been offered so far. We publish a complete chicken rRNA gene cluster sequence here, including <i>5’ETS</i> (1836 bp), <i>18S rRNA</i> gene (1823 bp), <i>ITS1</i> (2530 bp), <i>5</i>.<i>8S rRNA</i> gene (157 bp), <i>ITS2</i> (733 bp), <i>28S rRNA</i> gene (4441 bp) and <i>3’ETS</i> (343 bp). The rRNA gene cluster sequence of 11863 bp was assembled from raw reads and deposited to GenBank under KT445934 accession number. The assembly was validated through <i>in situ</i> fluorescent hybridization analysis on chicken metaphase chromosomes using computed and synthesized specific probes, as well as through the reference assembly against <i>de novo</i> assembled rRNA gene cluster sequence using sequenced fragments of BAC-clone containing chicken NOR (nucleolus organizer region). The results have confirmed the chicken rRNA gene cluster validity.</p></div

Localization of assembled rRNA gene cluster fragments on chicken mitotic chromosomes.

<p>FISH with (A) <i>5’ETS–18S</i> rDNA fragment probe, (D) <i>ITS1–5</i>.<i>8S</i> rDNA fragment probe, (B, E) WAG137G04 BAC probe, which contains NOR, marker of GGA16, (C, F) merge. A, D–green fluorescence; B, E–red fluorescence; C, F–merge. Chromosomes are counterstained with DAPI (blue). Bar – 5 μm.</p

GenBank representation of <i>ITS1</i> and <i>ITS2</i> sequences.

<p>GenBank representation of <i>ITS1</i> and <i>ITS2</i> sequences.</p

The list of primers for amplification of target regions of the assembled ribosomal cluster sequence.

<p>The list of primers for amplification of target regions of the assembled ribosomal cluster sequence.</p

WGS contigs and annotated sequences used to verify the chicken ribosomal cluster assembly.

<p>WGS contigs and annotated sequences used to verify the chicken ribosomal cluster assembly.</p

Ribosomal DNA structure (after Singer and Berg, 1991).

<p>Ribosomal DNA structure (after Singer and Berg, 1991).</p

The chicken rRNA gene cluster structure and features.

<p>The chicken rRNA gene cluster structure and features.</p

The rejected sequences of chicken rDNA.

<p>The rejected sequences of chicken rDNA.</p

Coordination to Imidazole Ring Switches on Phosphorescence of Platinum Cyclometalated Complexes: The Route to Selective Labeling of Peptides and Proteins via Histidine Residues

In this study, we have shown that substitution of chloride ligand for imidazole (Im) ring in the cyclometalated platinum complex Pt­(phpy)­(PPh₃)Cl (<b>1</b>; phpy, 2-phenylpyridine; PPh₃, triphenylphosphine), which is nonemissive in solution, switches on phosphorescence of the resulting compound. Crystallographic and nuclear magnetic resonance (NMR) spectroscopic studies of the substitution product showed that the luminescence ignition is a result of Im coordination to give the [Pt­(phpy)­(Im)­(PPh₃)]Cl complex. The other imidazole-containing biomolecules, such as histidine and histidine-containing peptides and proteins, also trigger luminescence of the substitution products. The complex <b>1</b> proved to be highly selective toward the imidazole ring coordination that allows site-specific labeling of peptides and proteins with <b>1</b> using the route, which is orthogonal to the common bioconjugation schemes via lysine, aspartic and glutamic acids, or cysteine and does not require any preliminary modification of a biomolecule. The utility of this approach was demonstrated on (i) site-specific modification of the ubiquitin, a small protein that contains only one His residue in its sequence, and (ii) preparation of nonaggregated HSA-based Pt phosphorescent probe. The latter particles easily internalize into the live HeLa cells and display a high potential for live-cell phosphorescence lifetime imaging (PLIM) as well as for advanced correlation PLIM and FLIM experiments