Papers by Cassandra Smith
Cytogenetic and Genome Research, 1996
A DNA isolation procedure was developed by using triple-helix formation and magnetic separation. ... more A DNA isolation procedure was developed by using triple-helix formation and magnetic separation. In this procedure, target DNA is captured by a biotinylated oligonu- cleotide via intermolecular triplex formation, bound to strepta- vidin-coated magnetic beads, and recovered in double- stranded form by elution with a mild alkaline buffer that destabilizes the triple helix. The effectiveness of the procedure was demonstrated by a model experiment with an artificially reconstructed library and, also, by the isolation of (dT- dC)",(dG-dA), dinucleotide repeats from a human genomic library. This procedure provides a prototype for other triplex- mediated DNA isolation technologies.
The EMBO Journal, 1988
Communicated by B.Pernis We present a detailed analysis of the content and organization of the hu... more Communicated by B.Pernis We present a detailed analysis of the content and organization of the human immunoglobulin VH locus. Human VH genes representing five distinct families were isolated, including novel members belonging to two out of three of the known VH gene families (VH1 and VH3) as well as members of three new families (VH4, VH5, and VA6). We report the nucleotide sequence of 21 novel human VH genes, many of which belong to the three new VH gene families. In addition, we provide a preliminary analysis of the organization of these gene segments over the full extent of the locus. We find that the five multi-segment families (VH1-5) have members interspersed over nearly the full 1500-2000 kb of the VH locus, and estimate that the entire heavy chain locus covers 2500 kb or less. Finally, we provide the first report of the physical linkage of the variable and constant loci of a human Ig gene family by demonstrating that the most proximal known human VH segments lie within 100 kb of the constant region locus.
Journal of Bacteriology, 1988
The termination of protein synthesis in Escherichia coli requires two codon-specific factors term... more The termination of protein synthesis in Escherichia coli requires two codon-specific factors termed RF1 and RF2. RF1 mediates UAA- and UAG-directed termination, while RF2 mediates UAA- and UGA-directed termination. The genes encoding these factors have been isolated and sequenced, and RF2 was found to be encoded in two separate reading frames. The map position of RF1 has been reported as 27 min on the E. coli chromosome, while the RF2 map position has not yet been identified. In this study, two new and independent methods for gene mapping, using pulsed field gel electrophoresis and an ordered bacteriophage library spanning the entire chromosome, were used to localize the map position of the RF2 gene. In addition, the location of the RF1 gene was more precisely defined. The RF2 gene is located at 62.3 min on the chromosome, while the RF1 gene is located at 26.7 min. This approach to mapping cloned genes promises to be a rapid and simple means for determining the gene order of the gen...
John Wiley & Sons, Inc. eBooks, Apr 2, 2003
Zoological Journal of the Linnean Society, 2018
Group-living behaviour is rare in spiders but has evolved repeatedly, yielding several species, s... more Group-living behaviour is rare in spiders but has evolved repeatedly, yielding several species, some showing cooperation among close kin, and others living in colonies where each female builds its own web and is territorial. The most frequent origins of group living are seen in the cobweb spiders (Theridiidae) that commonly build three-dimensional webs and show extensive maternal care, both putatively pre-adaptive traits to spider sociality. A very unusual behaviour was recently discovered in the theridiid genus Chikunia, where two distinct but related species occur in mixed-species colonies with potentially indiscriminate brood care. These mixed colonies consist of Chikunia nigra and a newly discovered species. Here, we describe the new species, Chikunia bilde sp. nov., and summarize the unique biology of this species pair. We also place the origin of mixed-species group living in a phylogenetic context, firmly confirming the placement of Chikunia within the clade (lost colulus cla...
Mutation Research/DNA Repair, 1996
CSH protocols, 2006
The isolation of genomic DNA from whole blood (10 ml) using the Wizard Genomic DNA Purification K... more The isolation of genomic DNA from whole blood (10 ml) using the Wizard Genomic DNA Purification Kit is based on a four-step process: lysis of the red blood cells and removal of the soluble fraction; lysis of the white blood cells and their nuclei; selective removal of ...
CSH protocols, 2006
The Wizard SV Gel and PCR Clean-Up System provides a silica-based method for the purification of ... more The Wizard SV Gel and PCR Clean-Up System provides a silica-based method for the purification of PCR fragments from agarose gel slices. The DNA band (s) of interest is excised from the gel and dissolved in a guanidine isothiocyanate solution. This mixture is ...
Proceedings of the National Academy of Sciences of the United States of America, Apr 1, 1978
Different inducing agents and treatments produced distinctly different kinetic patterns of inacti... more Different inducing agents and treatments produced distinctly different kinetic patterns of inactivation of prophage repressor molecules. The different patterns were related to differences in the initial altered states of DNA that were produced. The timing of appearance of DNA degradation was corelated with the time needed for repressor inactivation. These characteristics suggest that all the inducing treatments lead to the formation of a final predegradative DNA structure(s) (probably involving scissions) that is acted on by specific DNases, including the recBC DNase, to produce the signals for the induction of prophage.
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), 1996
Nucleic Acids Research, 1992
Biochemistry, Dec 1, 1988
The resolution of pulsed-field gel electrophoresis is dramatically affected by the number and con... more The resolution of pulsed-field gel electrophoresis is dramatically affected by the number and configuration of the electrodes used, because these alter the shape of the applied electrical fields. Here we present calculations and experiments on the effect of electrode position in one of the most commonly used pulsed-field gel electrophoresis configurations. The goal was to explore which aspects of the electrical field shape correlate with improved electrophoretic resolution. The most critical variable appears to be the angle between the alternate electrical fields. The most effective electrode configurations yield angles of more than 1 loo. A continually increasing angle between the fields produces band sharpening that greatly enhances the resolution.
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), 2002
Cold Spring Harbor Symposia on Quantitative Biology, 1979
Inhibition of DNA replication in bacteria induces a variety of cellular processes which have been... more Inhibition of DNA replication in bacteria induces a variety of cellular processes which have been designated as SOS functions (Witkin 1974; Radman 1974). A typical example of the SOS functions is prophage induction which was originally discovered by Lwoff in Bacillus ...
Biochemistry, Dec 1, 1988
The resolution of pulsed-field gel electrophoresis is dramatically affected by the number and con... more The resolution of pulsed-field gel electrophoresis is dramatically affected by the number and configuration of the electrodes used, because these alter the shape of the applied electrical fields. Here we present calculations and experiments on the effect of electrode position in one of the most commonly used pulsed-field gel electrophoresis configurations. The goal was to explore which aspects of the electrical field shape correlate with improved electrophoretic resolution. The most critical variable appears to be the angle between the alternate electrical fields. The most effective electrode configurations yield angles of more than 1 loo. A continually increasing angle between the fields produces band sharpening that greatly enhances the resolution.
Uploads
Papers by Cassandra Smith