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Full-Text Articles in Cell Biology

Localization Of Hiv-1 Rna In Mammalian Nuclei, Guohong Zhang, Maria L. Zapp, Guochen Yan, Michael R. Green Oct 1996

Localization Of Hiv-1 Rna In Mammalian Nuclei, Guohong Zhang, Maria L. Zapp, Guochen Yan, Michael R. Green

Open Access Articles

The Rev protein of human immunodeficiency virus type 1 (HIV-1) facilitates the nuclear export of unspliced and partially spliced viral RNAs. In the absence of Rev, these intron-containing HIV-1 RNAs are retained in the nucleus. The basis for nuclear retention is unclear and is an important aspect of Rev regulation. Here we use in situ hybridization and digital imaging microscopy to examine the intranuclear distributions of intron-containing HIV RNAs and to determine their spatial relationships to intranuclear structures. HeLa cells were transfected with an HIV-1 expression vector, and viral transcripts were localized using oligonucleotide probes specific for the unspliced or ...


Mitochondrial Dna Of The Thatching Ant, Formica Obscuripes, Gregory Park Apr 1996

Mitochondrial Dna Of The Thatching Ant, Formica Obscuripes, Gregory Park

Life and Environmental Sciences Undergraduate Theses

In a continuing attempt to purify mitochondrial DNA from the thatching ant, modifications were made to a previously developed extraction procedure. Although mitochondria were highly enriched in a subcellular fraction derived from the heads of the ants, when DNA purified from the fraction by an alkaline lysis procedure was electrophoresed, inconsistent results were obtained. Bands in the gel show a molecule larger than 22 kilobase pairs, which is not expected of mtDNA.


Preliminary Attempts To Purify Genomic And Mitochondrial Dna From A Freshwater Sponge, Derek Gordon Apr 1996

Preliminary Attempts To Purify Genomic And Mitochondrial Dna From A Freshwater Sponge, Derek Gordon

Life and Environmental Sciences Undergraduate Theses

This project was intended to be a pair of preliminary experiments from which more detailed and specific experiments could be expanded. There were two procedures used in carrying out this study involving the isolation of DNA from a freshwater sponge. First, genomic DNA was isolated and purified. This genomic DNA was digested with the restriction endonuclease EcoR1 and then analyzed using agarose gel electrophoresis. The results showed an accumulation of the sponge DNA in one major band roughly slightly larger than the 21226 bp band generated by EcoR1 digestion of X-phage DNA. The second part of this experiment was an ...


Heat Shock Factor Gains Access To The Yeast Hsc82 Promoter Independently Of Other Sequence-Specific Factors And Antagonizes Nucleosomal Repression Of Basal And Induced Transcription, Alexander M. Erkine, C. C. Adams, T. Diken, D. S. Gross Jan 1996

Heat Shock Factor Gains Access To The Yeast Hsc82 Promoter Independently Of Other Sequence-Specific Factors And Antagonizes Nucleosomal Repression Of Basal And Induced Transcription, Alexander M. Erkine, C. C. Adams, T. Diken, D. S. Gross

Scholarship and Professional Work – COPHS

Transcription in eukaryotic cells occurs in the context of chromatin. Binding of sequence-specific regulatory factors must contend with the presence of nucleosomes for establishment of a committed preinitiation complex. Here we demonstrate that the high-affinity binding site for heat shock transcription factor (HSF) is occupied independently of other cis-regulatory elements and is critically required for preventing nucleosomal assembly over the yeast HSC82 core promoter under both noninducing (basal) and inducing conditions. Chromosomal mutation of this sequence, termed HSE1, erases the HSF footprint and abolishes both transcription and in vivo occupancy of the TATA box. Moreover, it dramatically reduces promoter chromatin ...


Reconstruction Of Ribosomal Subunits And Rdna Chromatin Imaged By Scanning Force Microscopy, Wolfgang Fritzsche, Linda Martin, Drena Dobbs, Daniel Jondle, Richard Miller, James Vesenka, Eric Henderson Jan 1996

Reconstruction Of Ribosomal Subunits And Rdna Chromatin Imaged By Scanning Force Microscopy, Wolfgang Fritzsche, Linda Martin, Drena Dobbs, Daniel Jondle, Richard Miller, James Vesenka, Eric Henderson

Zoology and Genetics Publications

Scanning force microscopy (SFM) reveals surface topography by scanning a sharp tip in close proximity to the sample. Due to tip–sample interaction, artificial broadening of the real surface structure with the tip geometry occurs. One approach for image reconstruction is the use of calibration standards, preferably in the size range of the samples. In the present study, an image reconstruction method based on colloidal gold as a geometric standard was used to reconstruct SFM images of biomolecules. Sample and calibration standard size were in the nanometer range, and the standards were coadsorbed with the specimen. Raw and reconstructed images ...


Regulation Of Dna Replication In Xenopus Laevis , Jing Fang Jan 1996

Regulation Of Dna Replication In Xenopus Laevis , Jing Fang

Retrospective Theses and Dissertations

The purpose of my research project is to make an attempt to understand some aspects of eukaryotic DNA replication by studying how this process is regulated positively or negatively in different physiological conditions. Using Xenopus egg extracts as the in vitro replication system, I studied the inhibitors of DNA replication found in nuclei of Xenopus quiescent cells. Replication of nuclei isolated from quiescent Xenopus cells was barely detectable in interphase extracts of Xenopus laevis eggs, although Xenopus sperm chromatin was replicated with about 100% efficiency in the same extracts. The evidence of the inhibitors came further from the fact that ...