Laura E Rosen

Publications of Laura E Rosen

• Detection of Yersinia pestis DNA in prairie dog-associated fleas by polymerase chain reaction assay of purified DNA.

  Authors: Karen A Griffin, Daniel J Martin, Laura E Rosen, Michael A Sirochman, Daniel P Walsh, Lisa L Wolfe, Michael W Miller

  Journal of wildlife diseases. 04/2010; 46(2):636-43.

  We evaluated, refined, and applied well-established polymerase chain reaction (PCR) techniques for detecting Yersinia pestis DNA in fleas (mainly Oropsylla spp.) collected from prairie dog (CynomysWe evaluated, refined, and applied well-established polymerase chain reaction (PCR) techniques for detecting Yersinia pestis DNA in fleas (mainly Oropsylla spp.) collected from prairie dog (Cynomys spp.) burrows. Based on results from PCR of avirulent Y. pestis strain A1122 DNA, we used DNA purification and primers for the plasminogen activator gene to screen field-collected fleas. We detected Y. pestis DNA in flea pools from two black-tailed prairie dog (Cynomys ludovicianus) colonies with evidence of recent plague epizootics, and from one of four white-tailed prairie dog (Cynomys leucurus) colony complexes (Wolf Creek) where evidence of epizootic plague was lacking. Relative flea abundance and occurrence of Y. pestis DNA among flea pools appeared to vary over time at Wolf Creek. Both DNA purification and primer sequences appeared to influence the likelihood of detecting Y. pestis DNA by PCR in fleas collected from prairie dog burrows in the absence of observed epizootic plague. Presence of Y. pestis plasmid DNA in fleas collected from prairie dog burrows at Wolf Creek may represent evidence that infected fleas were somehow being maintained in that system between epizootics, consistent with the hypothesized enzootic maintenance of plague in prairie dog colony complexes elsewhere.

• Effects of selenium supplementation and sample storage time on blood indices of selenium status in bighorn sheep.

  Authors: Laura E Rosen, Daniel P Walsh, Lisa L Wolfe, Cathy L Bedwell, Michael W Miller

  Journal of wildlife diseases. 08/2009; 45(3):795-801.

  Periodic pneumonia outbreaks cause large-scale die-offs that threaten the viability of bighorn sheep (Ovis canadensis) populations. Bighorns are highly susceptible to pneumonia, and in some casesPeriodic pneumonia outbreaks cause large-scale die-offs that threaten the viability of bighorn sheep (Ovis canadensis) populations. Bighorns are highly susceptible to pneumonia, and in some cases this susceptibility may be exacerbated by trace mineral deficiencies. To evaluate responses to injectable selenium supplementation, eight captive bighorn sheep were treated with either an injectable sodium selenite supplement or a saline control. We collected 6-ml blood aliquots before and at 1, 6, and 12 wk posttreatment. We submitted one set of aliquots immediately to measure selenium (Se) and zinc (Zn) concentrations and glutathione-peroxidase (GSH-Px) activity; additional aliquots were held at about 22 C and then submitted at 1, 3, and 7 days postcollection to assess effects of storage on these measures. Neither Se nor GSH-Px were affected by selenite injections. Both Se and GSH-Px demonstrated small linear decays over the 7-day storage period (0.011 ppm/day [SE=0.0027] and 15.78 mmole/l/sec/day [SE=6.88], respectively); in contrast, Zn concentrations in stored samples increased logarithmically (0.35 ppm/day on the natural log scale). Blood Se and GSH-Px were not correlated in sampled bighorns; however, because all values for both measures were within normal limits, lack of correlation did not affect interpretation of these data in our study.

• Homing endonuclease I-CreI derivatives with novel DNA target specificities.

  Authors: Laura E Rosen, Holly A Morrison, Selma Masri, Michael J Brown, Brendan Springstubb, Django Sussman, Barry L Stoddard, Lenny M Seligman

  Nucleic acids research. 02/2006; 34(17):4791-800.

  Homing endonucleases are highly specific enzymes, capable of recognizing and cleaving unique DNA sequences in complex genomes. Since such DNA cleavage events can result in targetedHoming endonucleases are highly specific enzymes, capable of recognizing and cleaving unique DNA sequences in complex genomes. Since such DNA cleavage events can result in targeted allele-inactivation and/or allele-replacement in vivo, the ability to engineer homing endonucleases matched to specific DNA sequences of interest would enable powerful and precise genome manipulations. We have taken a step-wise genetic approach in analyzing individual homing endonuclease I-CreI protein/DNA contacts, and describe here novel interactions at four distinct target site positions. Crystal structures of two mutant endonucleases reveal the molecular interactions responsible for their altered DNA target specificities. We also combine novel contacts to create an endonuclease with the predicted target specificity. These studies provide important insights into engineering homing endonucleases with novel target specificities, as well as into the evolution of DNA recognition by this fascinating family of proteins.