Biomedical subjects

Paul M Lizardi

Publications and source records attributed to Paul M Lizardi.

4 recordsLinked to original sources

PubMed2006

RCA-enhanced protein detection arrays.

There are many instances in which it is desirable to generate profiles of the relative abundance of a multiplicity of protein species. Examples include studies in embryonic development, immunobiology, drug responses, cancer biology, biomarkers, and so on. Microarray formats provide a convenient, high-throughput vehicle for generating such profiles, and the repertoire of proteins that can be measured is growing continuously as larger panels of specific antibodies become available. Here we describe methods for the use of antibody microarrays, whereby the detection of specifically bound antigens is enhanced by rolling circle amplification (RCA). RCA-enhanced protein detection on antibody microarrays provides a means for rapid protein profiling at high sensitivity. The set of RCA reagents remains unchanged for different microarray formats and compositions, and signal readout is performed using standard fluorescent dyes and scanners. The method is sensitive enough for the most challenging applications, such as the detection of low-abundance components of human serum.

Animals↗

PubMed2005

In situ detection of specific DNA double strand breaks using rolling circle amplification.

We have developed a method to localize DNA double strand breaks (DSBs) in situ in cultured mammalian cells. Adenoviruses encoding Saccharomyces cerevisiae HO endonuclease and its cleavage site were used to induce site-specific DSBs. Rolling circle amplification (RCA), a sensitive method that allows the detection of single molecular event by rapid isothermal amplification, was used to localize the broken ends in situ. Punctate RCA signals were only seen in the cells that had been infected with both adenoviruses encoding HO endonuclease and HO cleavage site, but not in the cells mock-infected or infected with the site or endonuclease virus only. With use of a chemical crosslinker, in situ RCA and immunofluorescence (IF) can be performed simultaneously on the same sample. This methodology provides a novel approach for investigation of DNA recombination, DNA repair, and checkpoint controls in mammalian cells.

Adenoviridae↗

PubMed2004

Expression profiling using a hexamer-based universal microarray.

We describe a transcriptional analysis platform consisting of a universal micro-array system (UMAS) combined with an enzymatic manipulation step that is capable of generating expression profiles from any organism without requiring a priori species-specific knowledge of transcript sequences. The transcriptome is converted to cDNA and processed with restriction endonucleases to generate low-complexity pools (approximately 80-120) of equal length DNA fragments. The resulting material is amplified and detected with the UMAS system, comprising all possible 4,096 (4(6)) DNA hexamers. Ligation to the arrays yields thousands of 14-mer sequence tags. The compendium of signals from all pools in the array-of-universal arrays comprises a full-transcriptome expression profile. The technology was validated by analysis of the galactose response of Saccharomyces cerevisiae, and the resulting profiles showed excellent agreement with the literature and real-time PCR assays. The technology was also used to demonstrate expression profiling from a hybrid organism in a proof-of-concept experiment where a T-cell receptor gene was expressed in yeast.

3' Untranslated Regions↗

PubMed2003

Whole genome analysis of genetic alterations in small DNA samples using hyperbranched strand displacement amplification and array-CGH.

Structural genetic alterations in cancer often involve gene loss or gene amplification. With the advent of microarray approaches for the analysis of the genome, as exemplified by array-CGH (Comparative Genomic Hybridization), scanning for gene-dosage alterations is limited only by issues of DNA microarray density. However, samples of interest to the pathologist often comprise small clusters of just a few hundred cells, which do not provide sufficient DNA for array-CGH analysis. We sought to develop a simple method that would permit amplification of the whole genome without the use of thermocycling or ligation of DNA adaptors, because such a method would lend itself to the automated processing of a large number of tissue samples. We describe a method that permits the isothermal amplification of genomic DNA with high fidelity and limited sequence representation bias. The method is based on strand displacement reactions that propagate by a hyperbranching mechanism, and generate hundreds, or even thousands, of copies of the genome in a few hours. Using whole genome isothermal amplification, in combination with comparative genomic hybridization on cDNA microarrays, we demonstrate the ability to detect gene losses in yeast and gene dosage imbalances in human breast tumor cell lines. Although sequence representation bias in the amplified DNA presents potential problems for CGH analysis, these problems have been overcome by using amplified DNA in both control and tester samples. Gene-dosage alterations of threefold or more can be observed with high reproducibility with as few as 1000 cells of starting material.

Breast Neoplasms↗