Identification of a single genome by electron paramagnetic resonance (EPR) with nitroxide-labeled oligonucleotide probes.

Nitroxide-labeled nucleic acids are used as a molecular size sensor to identify as few as one genome under polymerase chain reaction (PCR) conditions by electron paramagnetic resonance (EPR) spectroscopy. DNA identification is based on differences in the EPR spectra of mononitroxide-labeled nucleic acids. The experimental data imply that rapid DNA identification can be achieved in many systems by EPR at the molecular level.

An improved method for the analysis of Cryptosporidium parvum oocysts by matrix-assisted laser desorption/ionization time of flight mass spectrometry.

Cryptosporidium parvum oocysts were analyzed using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Sample preparation proved to be a crucial step in the acquisition of acceptable mass spectra. Oocysts of C. parvum and the matrix were mixed and held for at least 45 min to produce reproducible, representative mass spectra. Sporozoites were also excysted from oocysts, purified, and analyzed using MALDI-TOF MS. The mass spectra of the intact oocysts contained many of the same peaks found in the mass spectra of the sporozoites, suggesting that during analysis, the internal constituents, not just the oocyst wall, are ablated by the laser.

Transport of chemical and microbial compounds from known wastewater discharges: potential for use as indicators of human fecal contamination.

The quality of drinking and recreational water is currently (2005) determined using indicator bacteria. However, the culture tests used to analyze forthese bacteria require a long time to complete and do not discriminate between human and animal fecal material sources. One complementary approach is to use chemicals found in human wastewater, which would have the advantages of (1) potentially shorter analysis times than the bacterial culture tests and (2) being selected for human-source specificity. At 10 locations, water samples were collected upstream and at two successive points downstream from a wastewaster treatment plant (WWTP); a treated effluent sample was also collected at each WWTP. This sampling plan was used to determine the persistence of a chemically diverse suite of emerging contaminants in streams. Samples were also collected at two reference locations assumed to have minimal human impacts. Of the 110 chemical analytes investigated in this project, 78 were detected at least once. The number of compounds in a given sample ranged from 3 at a reference location to 50 in a WWTP effluent sample. The total analyte load at each location varied from 0.018 microg/L at the reference location to 97.7 microg/L in a separate WWTP effluent sample. Although most of the compound concentrations were in the range of 0.01-1.0 microg/L, in some samples, individual concentrations were in the range of 5-38 microg/L. The concentrations of the majority of the chemicals present in the samples generally followed the expected trend: they were either nonexistent or at trace levels in the upstream samples, had their maximum concentrations in the WWTP effluent samples, and then declined in the two downstream samples. This research suggests that selected chemicals are useful as tracers of human wastewater discharge.