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Full-Text Articles in Cell Biology

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 ...


Astrocyte Volume Regulation , Trent Allan Basarsky Jan 1996

Astrocyte Volume Regulation , Trent Allan Basarsky

Retrospective Theses and Dissertations

This dissertation deals with the regulation of synapse formation between cultured hippocampal neurons, and the volume dynamics of astrocytes during hyposmotic-induced swelling;The developmental time course of synapse formation in cultured hippocampal neurons was examined. After 12 days in culture (DIC) inhibitory and excitatory synapses formed which were sensitive to the N-type calcium channel antagonist [omega]-conotoxin GVIA ([omega]-CgTx) while, at 4 DIC, immature connections were present in which spontaneous, but rarely evoked, synaptic currents were detected. A comparison of 4 and 12 DIC neurons revealed the presence of the synaptic proteins rab3a, synapsin I, and synaptotagmin, but the ...


The Role Of Rat Brain Ptp-1 Surface Basic Residues In Substrate Reactivity , Deborah Sue Baedke Jan 1996

The Role Of Rat Brain Ptp-1 Surface Basic Residues In Substrate Reactivity , Deborah Sue Baedke

Retrospective Theses and Dissertations

Previous work by others has demonstrated that rat brain protein tyrosine phosphatase (rbPTP-1) exhibited increased reactivity toward substrates containing acidic residues N-terminal to phosphotyrosine. We show that substrates containing a single acidic residue C-terminal to the phosphotyrosine also enhanced reactivity with rbPTP-1. A substrate aspartate residue at the P+2 position exhibited the greatest enhancement of reactivity;Surface basic residues of rbPTP-1 were investigated for their role in the increased reactivity due to substrate acidic residues. Mutation of R47 or K120 to alanine decreased the enhancement of reactivity due to acidic residues N-terminal to phosphotyrosine by 78% and 73% respectively ...