Algae in cytologic smears.

OBJECTIVE: To desmonstrate the presence of algae in smears and establish their significance. STUDY DESIGN: Microscopic examination of smears stained by the Papanicolaou technique. RESULTS: We found 12 different species of algae, clustered in three categories: Cyanophita (blue algae), Chrysophyta (yellow algae) and Chlorophyta (green algae). CONCLUSION: Algae in smears are infrequently observed, with few bibliographic references. Their presence is due to intrinsic or extrinsic contamination. They may be confused with other structures, such as fungi, Charcott crystals or adenocarcinoma cells.     

Risk factors and transmission routes of the causative agents of campylobacteriosis in commercial poultry plants]

The study, carried out in two regions of the USSR and aimed at estimation of the contamination of products supplied by industrial poultry complexes (IPC), revealed that the contamination of these products was closely related to the Campylobacter contamination of the personnel of IPC. The causes of high Campylobacter contamination of the products of IPC at all technological stages of their production are described. The species, serovars and biovars of Campylobacter strains isolated from different sources were determined, which made it possible to carry out the specific and intraspecific differentiation of these strains.     

Fate and Transport of Contaminants in Indoor Air

Significant media and regulatory attention has been given to hazardous waste sites and to the remediation of such sites to protect nearby building occupants. Soil vapor intrusion (SVI) can be a major factor contributing to increased occupant expo sure to chemicals. However, there are many possible sources of indoor air pollution, thus complicating routine assessments. The intent of this paper is to provide an overview of the state of understanding related to chemical fate in the indoor environment. A generalized model is presented in the form of an ordinary differential equation that includes several terms that are not commonly accounted for in models involving the effects of SVI in indoor air. In addition to soil vapor intrusion several other sources of indoor contamination are described. Typical air exchange rates for residential dwellings are presented. Finally, recent findings related to the sorptive interactions between indoor air pollutants and indoor materials, as well as homogeneous and heterogeneous chemical reactions that can affect indoor air pollutants are described.     

A quality control algorithm for DNA sequencing projects.

Heterologous DNA sequences from rearrangements with the genomes of host cells, genomic fragments from hybrid cells, or impure tissue sources can threaten the purity of libraries that are derived from RNA or DNA. Hybridization methods can only detect contaminants from known or suspected heterologous sources, and whole library screening is technically very difficult. Detection of contaminating heterologous clones by sequence alignment is only possible when related sequences are present in a known database. We have developed a statistical test to identify heterologous sequences that is based on the differences in hexamer composition of DNA from different organisms. This test does not require that sequences similar to potential heterologous contaminants are present in the database, and can in principle detect contamination by previously unknown organisms. We have applied this test to the major public expressed sequence tag (EST) data sets to evaluate its utility as a quality control measure and a peer evaluation tool. There is detectable heterogeneity in most human and C.elegans EST data sets but it is not apparently associated with cross-species contamination. However, there is direct evidence for both yeast and bacterial sequence contamination in some public database sequences annotated as human. Results obtained with the hexamer test have been confirmed with similarity searches using sequences from the relevant data sets.     

Exfoliated oral mucosa cells as bioindicators of short- and long-term systemic titanium contamination

BackgroundHumans are exposed to exogenous sources of titanium-containing particles that can enter the body mainly by inhalation, ingestion, or dermal absorption. Given the widespread use of biomaterials in medicine, the surface of a titanium (Ti) biomedical device is a potential endogenous source of Ti ions and/or Ti-containing particles, such as TiO₂ micro-(MPs) and nano-particles (NPs), resulting from biotribocorrosion processes. Ti ions or Ti-containing particles may deposit in epithelial cells of the oral mucosa, and the latter may therefore serve as bioindicators of short and long-term systemic Ti contamination. The aim of the present study was to histologically and quantitatively evaluate the presence of Ti traces in cells exfoliated from the oral mucosa as possible bioindicators of systemic contamination with this metal at short and long-term experimental time pointsMethodsThirty Wistar rats were intraperitoneally injected with a suspension of titanium dioxide (TiO₂) (0.16 g/100 g body weight of TiO₂ in 5 ml of NaCl 0.9%) using 5 nm NPs (Group: TiO₂-NP5; n = 10), 45 µm MPs (Group: TiO₂-MP45; n = 10), or vehicle alone (Control group; n = 10). At one and six months post-injection, right-cheek mucosa cells were obtained by exfoliative cytology using a cytobrush; they were spray fixed and stained using Safranin or the Papanicolaou technique. The smears were cytologically evaluated (light microscopy) to determine the presence of particulate material, which was also analyzed microchemically (SEM-EDS). Left-cheek mucosa cells were similarly obtained and re-suspended in 5 ml of PBS (pH: 7.2–7.4); the samples corresponding to each group were pooled together and analyzed spectrometrically (ICP-MS) to determine Ti concentration in each of the studied groups. Blood samples were obtained for histological determination of the presence of particulate material on Safranin-stained blood smears and determination of plasma concentration of Ti by ICP-MSResultsDifferent size and shape metal-like particles were observed inside and outside epithelial cells in TiO₂-NP5 and TiO₂-MP45 cytological smears at both one and six months post-injection. EDS analysis showed the presence of Ti in the particles. ICP-MS revealed higher Ti concentrations in both TiO₂ injected groups compared to the control group. In addition, Ti concentration did not vary with time or particle size. Monocytes containing particles were observed in blood smears of TiO₂-exposed animals one- and six-months post-injection. Plasma levels of Ti were significantly higher in TiO₂-NP5- and TiO₂-MP45- exposed animals than in controls (p < 0.05), and Ti concentration was significantly higher at one month than at six months in both TiO₂-exposed groups (p < 0.05).ConclusionsCells exfoliated from the oral mucosa could be used as bioindicators of short- and long-term systemic contamination with Ti. Exfoliative cytology could be used as a simple, non-invasive, and inexpensive diagnostic method for monitoring biotribocorrosion of Ti implants and patient clinical follow-up.     

Variation in the incidence of AGUS between different patient populations

OBJECTIVE: To determine the frequency of atypical glandular cells of undetermined significance (AGUS) for three consecutive calendar years from three different referral sources. STUDY DESIGN: Cervicovaginal smears with a diagnosis of AGUS were identified from January 1995 through December 1997. The smears were submitted from three different sources: two were city government hospital clinics, one with predominantly African American and Hispanic patients and the other with predominantly Asian and Hispanic patients. The third referral source was private practitioners' offices with predominantly Caucasian patients. RESULTS: A diagnosis of AGUS was made in 707 cases, accounting for 0.56% of all smears examined. This was in contrast to 6,872 smears reported as atypical squamous cells of undetermined significance (ASCUS) (5.4%) and 3,347 reported as squamous intraepithelial lesions (SIL) or above (2.7%). The incidence of AGUS ranged from 0.16% to 1.00% among different patient populations. This difference was also noted in the rate of ASCUS and SIL in the same patient population. There was a steady increase in the rate of AGUS for each referral source during the study period. The overall rate of patients who underwent histologic evaluation and the incidence of biopsy-proven preinvasive and invasive lesions were 62.4% and 23%, respectively. There was no significant difference in the rate of significant lesions after a diagnosis of AGUS during the study period or between the three referral sources. CONCLUSION: The AGUS rate in our laboratory was low and within the range (0.17-1.83%) reported in the literature. The AGUS rate varies with different patient populations, particularly with the incidence of SIL and age distribution.     

Sources of PAHs to Sediments of the Elizabeth River,VA

Sediments collected from the Elizabeth River, VA, a highly contaminated subestu-ary of the James River, were analyzed for polycyclic aromatic hydrocarbons (PAHs). Select isomer ratios (BbF/BkF, BaA/chrysene, and IP/BghiP) and molecular weight fractions (ΣPAH_202/202-276 and ΣPAH_252/202-276) were identified as source indicators for two former wood-treatment facilities (Atlantic Wood and Eppinger & Russell) located on the southern branch of the Elizabeth River. These facilities are suspected as probable contributors to the high PAH contamination in sediments. Plots of the wood-treatment source indicators, along with those for coal, wood, and automotives, revealed a likely contribution from only one of the former wood-treatment facilities, in addition to the possible contribution of coal/coal gasification to PAH contamination in sediments of the main stem and southern branch of the Elizabeth River. By examining PAH isomer ratios from known or suspected sources, it is possible to distinguish multiple sources of PAHs to an ecosystem.     

Pollen grains in human cytology

This paper reports on pollen analyses carried out in the course of a ten-year investigation, on many thousands of cytological smears coming from various organs and systems of the human body, and prepared for diagnostic purposes. The frequency and the significance of the pollen records vary according to the specific cytological field taken into account. In the urinary sediment smears, nipple secretions, and needle aspirations the polliniferous smears are very few, and the pollen number per smear is low (max 14 pollen grains, belonging always or mostly to anemophilous species). In these cases, the pollen records evidence the airborne contamination during medical procedures, the same happens with most of cervico-vaginal smears. In some cervico-vaginal smears, the high frequency of pollen grains belonging to pharmaceutical taxa suggests that lavages with vegetable components were used by the patients before undergoing the test. In nasal, bronchial and conjunctival cytology greater amounts of polliniferous slides were recorded (in bronchial/nasal cytology also a higher number of pollen grains per smears, up to 114–428 respectively) and pollen spectra reflected the vegetational environment of the patients' living sites. In these cases, most pollen grains are thought to be really present on mucosae when the samples were taken. In these cytological fields pollen analysis may be useful for diagnostic purposes, above all in case of allergic pathology to detect the pollen grains causing the disease.     

Techniques for Contamination Assessment During Drilling for Terrestrial Subsurface Sediments

Details about the procedures for drilling a ca. 150 m long drill core in a terrestrial setting under contamination controlled conditions are presented. Different to previous studies we only used commercially available drilling equipment to reduce the cost of operation significantly. The goals were (1) to minimize, (2) to monitor and, if possible, to quantify the contamination of the recovered sediments, and (3) to identify the different sources of contamination. Both the potential contamination of the sample material by surface microorganisms and non-indigenous material was assessed. To estimate the infiltration of drill mud into the core, fluorescent microspheres, having about half the size as microorganisms, were added to the mud. The drilling technique used was mud rotary drilling. With the exception of the very beginning of the drilling operations, the drill mud was devoid of any allochthonous hydrocarbons potentially derived from the drilling equipment or drill additives, and its biomarker composition reflected the varying organo-facies that were penetrated. Due to the lack of allochthonous hydrocarbons in the drill mud, its infiltration into the sediment cannot be traced by organic geochemical biomarker analysis. Microspheres proved to be a sensitive tool for the assessment of infiltration of drill mud into the core. The concentration of microspheres in the drill mud decreased continuously during the drilling, most probably caused by seepage of mud through leaks and attachment of spheres to the surface scum in the mud pit. Microscopic enumeration of the microspheres showed great variability in the depth of penetration of mud into the core, apparently unaffected of lithology. The sampling of the core material in the laboratory was carried out inside an anaerobic chamber. Several techniques for subsampling were used, according to sediment properties. The overall results indicate that, if strict contamination control protocols are employed, it is possible to recover uncontaminated samples at reasonable cost with commercially available drilling equipment.     

Detection and typing of Campylobacter jejuni and Campylobacter coli and analysis of indicator organisms in three waterborne outbreaks in Finland

Waterborne outbreaks associated with contamination of drinking water by Campylobacter jejuni are rather common in the Nordic countries Sweden, Norway, and Finland, where in sparsely populated districts groundwater is commonly used without disinfection. Campylobacters, Escherichia coli, or other coliforms have rarely been detected in potential sources. We studied three waterborne outbreaks in Finland caused by C. jejuni and used sample volumes of 4,000 to 20,000 ml for analysis of campylobacters and sample volumes of 1 to 5,000 ml for analysis of coliforms and E. coli, depending on the sampling site. Multiple samples obtained from possible sources (water distribution systems and environmental water sources) and the use of large sample volumes (several liters) increased the chance of detecting the pathogen C. jejuni in water. Filtration of a large volume (1,000 to 2,000 ml) also increased the rate of detection of coliforms and E. coli. To confirm the association between drinking water contamination and illness, a combination of Penner serotyping and pulsed-field gel electrophoresis (digestion with SmaI and KpnI) was found to be useful. This combination reliably verified similarity or dissimilarity of C. jejuni isolates from patient samples, from drinking water, and from other environmental sources, thus confirming the likely reservoir of an outbreak.     

The "suspicious" gynecologic smear

"Suspicious" gynecologic smears from 842 patients over a seven-year period were analyzed for their causes and outcomes. The frequency of the cytologic diagnosis of "suspicious" ranged between 0.5% in 1979 and 1.44% in 1975 of all smears examined. Review of the smears showed that this classification was used to report a variety of conditions, including equivocal possible precancerous changes as well as the presence of severe inflammation, degenerative or atrophic changes, abnormal glandular cells and metaplasia. The cytologic follow-up, following anti-inflammatory or hormonal therapy, showed a conversion to negative findings in 65.1% of all cases, usually within 12 months. In 294 cases, histologic analysis became necessary, revealing precancerous changes or cancer in 147 patients (17.5% of the study group). Smears of postmenopausal women with suspicious glandular or endometrial cells received special analysis. Significant numbers of such cases had histologic findings positive for malignancy (20% of smears with glandular cells and 21.3% with endometrial cells), as did also smears showing post-irradiative changes (34.6%) or atrophic and degenerative changes (17.1%). Therefore, "suspicious" smears in these groups were considered to indicate an increased risk of malignancy. A regimen for the proper management of cases with "suspicious" smears has been established.     

Capillary electrophoresis-single strand conformation polymorphism for the detection of multiple mutations leading to tuberculosis drug resistance

For rate determinations of anaerobic metabolism it is essential to maintain strictly anoxic conditions throughout the experiment. However, even if oxygen contamination can be avoided while preparing the incubation containers, it is still possible that the incubation containers themselves contaminate the samples by oxygen diffusing from or through their plastic or rubber components. In this study, we investigated the sources and extent of oxygen contamination during anoxic incubations, and present solutions to minimize oxygen contamination. In particular, we investigated oxygen contamination in Labco® Exetainers, glass vials with a butyl rubber septum in the screw cap, which are frequently used in microbiological experiments. Our results show that significant oxygen contamination occurred at different stages during the incubation. Contamination occurred when Exetainers were either filled or incubated for more than 16 h under oxic atmosphere, but also under an oxygen-free atmosphere due to diffusion of oxygen out of the butyl rubber septum. Therefore, to avoid oxygen contamination during incubations, we suggest (1) filling and incubating the incubation containers under anoxic atmosphere (glove bag) and (2) deoxygenating all elastomers in sample processing and incubation equipment. If initial oxygen contamination cannot be avoided, introduction of an anoxic headspace might help extract oxygen from the incubated sample and present a buffer against oxygen diffusing out of the septum. We modeled the amount of oxygen diffusing out of butyl rubber septa under different conditions, and results fitted well with the observed oxygen contamination. Thus, the model can be used to predict oxygen contamination under varying conditions and for differently sized septa.     

Incidence and tracking of Escherichia coli O157:H7 in a major produce production region in California

Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995-2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness.     

Fast identification and removal of sequence contamination from genomic and metagenomic datasets

High-throughput sequencing technologies have strongly impacted microbiology, providing a rapid and cost-effective way of generating draft genomes and exploring microbial diversity. However, sequences obtained from impure nucleic acid preparations may contain DNA from sources other than the sample. Those sequence contaminations are a serious concern to the quality of the data used for downstream analysis, causing misassembly of sequence contigs and erroneous conclusions. Therefore, the removal of sequence contaminants is a necessary and required step for all sequencing projects. We developed DeconSeq, a robust framework for the rapid, automated identification and removal of sequence contamination in longer-read datasets (150 bp mean read length). DeconSeq is publicly available as standalone and web-based versions. The results can be exported for subsequent analysis, and the databases used for the web-based version are automatically updated on a regular basis. DeconSeq categorizes possible contamination sequences, eliminates redundant hits with higher similarity to non-contaminant genomes, and provides graphical visualizations of the alignment results and classifications. Using DeconSeq, we conducted an analysis of possible human DNA contamination in 202 previously published microbial and viral metagenomes and found possible contamination in 145 (72%) metagenomes with as high as 64% contaminating sequences. This new framework allows scientists to automatically detect and efficiently remove unwanted sequence contamination from their datasets while eliminating critical limitations of current methods. DeconSeq's web interface is simple and user-friendly. The standalone version allows offline analysis and integration into existing data processing pipelines. DeconSeq's results reveal whether the sequencing experiment has succeeded, whether the correct sample was sequenced, and whether the sample contains any sequence contamination from DNA preparation or host. In addition, the analysis of 202 metagenomes demonstrated significant contamination of the non-human associated metagenomes, suggesting that this method is appropriate for screening all metagenomes. DeconSeq is available at http://deconseq.sourceforge.net/.     

Hematoidin crystals in cervicovaginal smears. Review of 27 cases seen in one year

The occurrence of hematoidin crystals in cervicovaginal smears has recently been described. A prospective search for hematoidin crystals in smears taken during a one-year period was carried out, with a subsequent retrospective chart review. This study revealed that the occurrence of hematoidin crystals was more common than previously thought and was often associated with pregnancy or pregnancylike states. The clinical correlations and possible etiologies of this finding are discussed.     

Organic contamination problems in the Viking molecular analysis experiment

The combination of analytical instrumentation selected for the molecular analysis experiment can carry out a survey of the organic compounds present on Mars regardless of their origin. The high sensitivity of this analysis, the limited number of samples which can be analyzed, the close proximity to the landed spacecraft on the surface of Mars which is accessible to the sampling device, the implications of the positive detection of indigenous organic matter in the Martian soil, and our previous experience with meteorites and lunar samples point to the need for a carefully designed program to maintain the inteprity of the analyzed Martian surface samples. A principal problem in interpreting the results of an organic analysis of an extraterrestrial sample is that of distinguishing contaminating material from indigenous material when unknown types and amounts of contaminants make their way into the sample being analyzed. An approach for control of sample integrity in the Viking molecular analysis experiment has been devised which we believe will eliminate such problems. Basically this involves (1) placing an upper limit on the amount of terrestrial contamination that can be tolerated and still allow scientifically meaningful analyses, (2) identifying the potential sources of contamination and analyzing their relative significance, (3) establishing methods to control these sources, and (4) obtaining complete information on the chemical composition of potential contaminants. Our previous experience in the Apollo mission has been of great value in developing the Viking program, perhaps the most important carryover being the recognition of the importance of establishing a comprehensive contamination control program in the early stages of mission planning and hardware design. The upper limit of total allowable organic contamination has been established as 1 μg g^?1. The principal source types, or modes, which contribute to the contamination load have been identified, each requiring a different approach to control. Spacecraft outgassing is controlled by materials selection to minimize outgassing and hermetic sealing whenever possible. Particulate fallout is controlled by selection of materials, particulate seals, cleaning of the spacecraft exterior, and clean room handling. The cleanliness of the direct sample path is controlled by severe materials limitations, ultracleaning, and pressurized sealing of the assembled hardware. Analysis of the relative probabilities of the sources contributing to the allowable contamination and consideration of the practical aspects of achieving a desired level of control for a particular source has resulted in an allocation ‘tree’ whereby fractions of the total allowable contamination are distributed to the various individual sources. These efforts have pointed out the need for more information concerning some of these sources and have actually dictated certain design changes in the spacecraft. Additional information was obtained experimentally on descent engine exhaust characteristics which led to the use of an organically cleaner fuel. In summary, the early recognition in the Viking mission of the importance of organic contamination control has allowed the evolution of a complete contamination control program encompassing spacecraft design, mission operations, flight operations, and the design of the science instrumentation for the molecular analysis experiment.     

The Incidence of Asbestos Bodies in the Lungs at Random Necropsies in Montreal

The incidence of asbestos bodies in the lungs of adult patients selected at random, who died in four Montreal hospitals, was studied by examining fresh unstained smears of lungs obtained at necropsy. Two techniques were used for preparation of the smears and an arbitrary grading system was developed to estimate the degree of contamination of the lungs by asbestos bodies.Asbestos bodies were present in 48 out of 100 necropsies; they were found in 32 of 56 men (57%) and in 16 of 44 women (34%). Men were more heavily contaminated. The proportion of positive smears depended on the technique used and the amount of lung sampled. No particular association was noted between asbestos bodies in the lungs and the presence of cancer in the 33 patients in this series with malignant disease. The high incidence in this random series suggests that asbestos is a significant air contaminant in Montreal.     

Terrestrial contamination in Apollo lunar samples

The Apollo lunar samples were seen to offer a unique opportunity in the search for extraterrestrial organic matter without the ambiguity surrounding meteorite analysis due to their unknown contamination histories. The recognition that only a small amount of indigenous organic material was likely to be present in lunar samples combined with the extreme sensitivity of organic analysis methods made it clear that this opportunity could be realized only by carefully controlling the collection, processing, and analysis of the samples in order that they might remain free of significant levels of contamination. The contamination control procedures adopted are described and the analytical evidence obtained throughout the program on potential contamination sources is presented. The organic contaminants actually found in the lunar samples by the various investigators are summarized. It is shown that the program succeeded in providing investigators with samples containing less than 0.1 ppm total contamination.     

Detection and Typing of Campylobacter jejuni and Campylobacter coli and Analysis of Indicator Organisms in Three Waterborne Outbreaks in Finland

Waterborne outbreaks associated with contamination of drinking water by Campylobacter jejuni are rather common in the Nordic countries Sweden, Norway, and Finland, where in sparsely populated districts groundwater is commonly used without disinfection. Campylobacters, Escherichia coli, or other coliforms have rarely been detected in potential sources. We studied three waterborne outbreaks in Finland caused by C. jejuni and used sample volumes of 4,000 to 20,000 ml for analysis of campylobacters and sample volumes of 1 to 5,000 ml for analysis of coliforms and E. coli, depending on the sampling site. Multiple samples obtained from possible sources (water distribution systems and environmental water sources) and the use of large sample volumes (several liters) increased the chance of detecting the pathogen C. jejuni in water. Filtration of a large volume (1,000 to 2,000 ml) also increased the rate of detection of coliforms and E. coli. To confirm the association between drinking water contamination and illness, a combination of Penner serotyping and pulsed-field gel electrophoresis (digestion with SmaI and KpnI) was found to be useful. This combination reliably verified similarity or dissimilarity of C. jejuni isolates from patient samples, from drinking water, and from other environmental sources, thus confirming the likely reservoir of an outbreak.     

An Efficient Multistrategy DNA Decontamination Procedure of PCR Reagents for Hypersensitive PCR Applications

Background

PCR amplification of minute quantities of degraded DNA for ancient DNA research, forensic analyses, wildlife studies and ultrasensitive diagnostics is often hampered by contamination problems. The extent of these problems is inversely related to DNA concentration and target fragment size and concern (i) sample contamination, (ii) laboratory surface contamination, (iii) carry-over contamination, and (iv) contamination of reagents.

Methodology/Principal Findings

Here we performed a quantitative evaluation of current decontamination methods for these last three sources of contamination, and developed a new procedure to eliminate contaminating DNA contained in PCR reagents. We observed that most current decontamination methods are either not efficient enough to degrade short contaminating DNA molecules, rendered inefficient by the reagents themselves, or interfere with the PCR when used at doses high enough to eliminate these molecules. We also show that efficient reagent decontamination can be achieved by using a combination of treatments adapted to different reagent categories. Our procedure involves γ- and UV-irradiation and treatment with a mutant recombinant heat-labile double-strand specific DNase from the Antarctic shrimp Pandalus borealis. Optimal performance of these treatments is achieved in narrow experimental conditions that have been precisely analyzed and defined herein.

Conclusions/Significance

There is not a single decontamination method valid for all possible contamination sources occurring in PCR reagents and in the molecular biology laboratory and most common decontamination methods are not efficient enough to decontaminate short DNA fragments of low concentration. We developed a versatile multistrategy decontamination procedure for PCR reagents. We demonstrate that this procedure allows efficient reagent decontamination while preserving the efficiency of PCR amplification of minute quantities of DNA.