transfection-molecular-clone-naegleria-gruberi-rdna-into-n-gruberi

Transfection of a Molecular Clone of <i>Naegleria gruberi</i> rDNA into <i>N. gruberi</i> Trophozoites

All ribosomal genes of Naegleria trophozoites are maintained in a closed circular extrachromosomal ribosomal DNA (rDNA) containing element (CERE). While ...

Washburn University

The circular extrachromosomal element of  strain EGB was linearized, molecularly cloned, and fully sequenced. The sequence comprises 14,007 bp and encodes the organism's rRNA genes, two potential open reading frames, and numerous repeated sequence regions.

Complete Genome Sequence of the Circular Extrachromosomal Element of  Strain EGB Ribosomal DNA.

The genes encoding the ribosomal RNA (rRNA) subunits of the amoeba Naegleria gruberi are encoded in a relatively uncommon arrangement: on a circular extrachromosomal DNA element with each organism carrying about 4,000 copies of the element. As complete sequence analysis of the N. gruberi chromosomal DNA revealed no copy of the rRNA genes, these extrachromosomal elements must therefore replicate autonomously. We reported elsewhere the molecular cloning and the complete sequence analysis of the entire rRNA gene-containing element of N. gruberi (strain EG). Using neutral/neutral two-dimensional agarose electrophoresis, the region in the element enclosing the single replication origin using DNA from asynchronous and axenically propagated N. gruberi populations was localized within a 2.1 kbp fragment located approximately 2,300bp from the 18S rRNA gene and 3,700bp from the 28S rRNA gene. The results indicate that replication occurs from a single origin via a theta-type mode of replication rather than by a rolling circle mode. Further, G-quadruplex elements, often located near DNA replication origins, occur in and near this fragment in a repeated sequence.

Mapping the Single Origin of Replication in the Naegleria gruberi Extrachromosomal DNA Element.

The circular extrachromosomal ribosomal DNA (rDNA) element of  strain LEE was molecularly cloned and fully sequenced. The element comprises 15,786 bp and contains a single copy of the organism's rDNA cistron. The nonribosomal sequence contains five potential open reading frames, two large direct repeat sequences, and numerous smaller repeated-sequence regions.

Article	Year
Complete Genome Sequence of the Circular Extrachromosomal Element of Strain EGB Ribosomal DNA. Genome announcements\| PubMed ID: 29439032	2018
Mapping the Single Origin of Replication in the Naegleria gruberi Extrachromosomal DNA Element. Protist\| PubMed ID: 30954840	2019
Complete Genome Sequence of the Naegleria fowleri (Strain LEE) Closed Circular Extrachromosomal Ribosomal DNA Element. Microbiology resource announcements\| PubMed ID: 33272991	2020

John C. Mullican

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