Chromosomal locations of major tRNA gene clusters of Xenopus laevis

Narayanswami, Sandya; Doering, Jeffrey L.; Fokta, Frank J.; Rosenthal, Dean S.; Nguyen, Thanh-Nhan; Hamkalo, Barbara A.

doi:10.1007/s004120050093

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, a single chromosomal site may account for 1200 of the 7800 -9600 tRNA gene copies. The chromosomal location of two other similar tRNA clones has also been determined by in situ hybridization (Narayanswami et al, 1995). One of them is at or very near the same locus as the 3.18-kb clone and the other is on another chromosome.…”

Section: Pol III Transcription Loops On Lampbrush Chromosomesmentioning

confidence: 99%

RNA Polymerase III in Cajal Bodies and Lampbrush Chromosomes of theXenopusOocyte Nucleus

Murphy

Wang

Roeder

et al. 2002

MBoC

View full text Add to dashboard Cite

We used immunofluorescence to study the distribution and targeting of RNA polymerase (pol) III subunits and pol III transcription factors in the Xenopus laevis oocyte nucleus. Antibodies against several of these proteins stained Cajal bodies and approximately 90 specific sites on the lampbrush chromosomes. Some of the chromosomal sites had been identified previously by in situ hybridization as the genes for 5S rRNA. The remaining sites presumably encode tRNAs and other pol III transcripts. Pol III sites were often resolvable as loops similar to the much more abundant pol II loops, but without a matrix detectable by phase contrast or differential interference contrast. This morphology is consistent with the transcription of short repeated sequences. Hemagglutinin-tagged transcripts encoding core subunits and transcription factors were injected into the oocyte cytoplasm, and the distribution of newly translated proteins inside the nucleus was monitored by immunostaining. Cajal bodies were preferentially targeted by these proteins, and in some cases the chromosomal sites were also weakly stained. The existence of pol III subunits and pol III transcription factors in Cajal bodies and their targeting to these organelles are consistent with a model of Cajal bodies as sites for preassembly of the nuclear transcription machinery.

show abstract

Section: Pol III Transcription Loops On Lampbrush Chromosomesmentioning

confidence: 99%