Multi-laboratory evaluations of the performance of Catellicoccus marimammalium PCR assays developed to target gull fecal sources

Here we report results from a multi-laboratory (n = 11) evaluation of four different PCR methods targeting the 16S rRNA gene of Catellicoccus marimammalium originally developed to detect gull fecal contamination in coastal environments. The methods included a conventional end-point PCR method, a SYBR^® Green qPCR method, and two TaqMan^® qPCR methods. Different techniques for data normalization and analysis were tested. Data analysis methods had a pronounced impact on assay sensitivity and specificity calculations. Across-laboratory standardization of metrics including the lower limit of quantification (LLOQ), target detected but not quantifiable (DNQ), and target not detected (ND) significantly improved results compared to results submitted by individual laboratories prior to definition standardization. The unit of measure used for data normalization also had a pronounced effect on measured assay performance. Data normalization to DNA mass improved quantitative method performance as compared to enterococcus normalization. The MST methods tested here were originally designed for gulls but were found in this study to also detect feces from other birds, particularly feces composited from pigeons. Sequencing efforts showed that some pigeon feces from California contained sequences similar to C. marimammalium found in gull feces. These data suggest that the prevalence, geographic scope, and ecology of C. marimammalium in host birds other than gulls require further investigation. This study represents an important first step in the multi-laboratory assessment of these methods and highlights the need to broaden and standardize additional evaluations, including environmentally relevant target concentrations in ambient waters from diverse geographic regions.     

One-trial cocaine-induced behavioral sensitization in preweanling rats: Role of contextual stimuli.

Using a one-trial procedure, preweanling rats exhibit robust sensitization regardless of whether drug pretreatment and testing occur in the same or different environments. The purpose of the present study was to determine whether one-trial context-specific and context-independent sensitization of preweanling rats could be dissociated by varying the pretreatment dose of cocaine, by varying the pretreatment drug, or by minimizing interoceptive cues. In Experiments 1a and 1b, rats were pretreated with a broad dose range of cocaine (0–40 mg/kg) before placement in a novel activity chamber or the home cage. In Experiment 2, rats were pretreated with a locomotor-enhancing drug (e.g., methylphenidate, U50,488, or MK-801) before placement in a novel activity or anesthesia chamber. In Experiment 3, rats were anesthetized with isoflurane before cocaine administration to minimize the effects of interoceptive and injection cues. In all experiments, rats were challenged with cocaine on the test day (24 hr later), with locomotion being measured in activity chambers. Results showed that (a) the pretreatment dose of cocaine (10–40 mg/kg) did not differentially affect context-specific and context-independent sensitization; (b) cross-sensitization between methylphenidate and cocaine was observed in the context-specific condition, but not when using a context-independent procedure; and (c) sensitization was evident if injection and interoceptive cues were minimized. One possibility is that associative processes do not modulate the one-trial sensitization of preweanling rats. Alternatively, “unitization” may cause preweanling rats to treat the different environments as equivalent, thus permitting robust sensitization even when drug pretreatment and testing occur in different environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Swimmer risk of gastrointestinal illness from exposure to tropical coastal waters impacted by terrestrial dry-weather runoff

This study used molecular methods to measure concentrations of four enteric viruses (adenovirus, enterovirus, norovirus GI, and norovirus GII) and fecal source tracking markers (human, ruminant, and pig Bacteroidales) in land-based runoff from 22 tropical streams on O'ahu, Hawai'i. Each stream was sampled twice in the morning and afternoon during dry weather. Viruses and human Bacteroidales were widespread in the streams. Watershed septic tank densities were positively associated with higher occurrence of human Bacteroidales and norovirus. There were no associations between occurrence of viruses and fecal indicator concentrations. Virus concentrations and previously reported culturable Salmonella and Campylobacter were used as inputs to a quantitative microbial risk assessment (QMRA) model to estimate the risk of acquiring gastrointestinal (GI) illness from swimming in tropical marine waters adjacent to discharging streams. Monte Carlo methods were used to incorporate uncertainties in the dilution of stream discharge with seawater, swimmer ingestion volumes, pathogen concentrations, and dose-response parameters into the model. Median GI illness risk to swimmers from exposure to coastal waters adjacent to the 22 streams ranged from 0 to 21/1000. GI illness risks from viral exposures were generally orders of magnitude greater than bacterial exposures. Swimming adjacent to streams positive for norovirus or adenovirus resulted in the highest risks. The median risk adjacent to each stream was positively, significantly correlated to the concentration of Clostridium perfringens in the stream. Although a number of important assumptions were made to complete the QMRA, results suggest land-based runoff in the tropics as a potential source of GI illness risk, with pathogens coming from both human and nonhuman nonpoint sources including septic tanks.     

Comparison of PCR and quantitative real-time PCR methods for the characterization of ruminant and cattle fecal pollution sources

The State of California has mandated the preparation of a guidance document on the application of fecal source identification methods for recreational water quality management. California contains the fifth highest population of cattle in the United States, making the inclusion of cow-associated methods a logical choice. Because the performance of these methods has been shown to change based on geography and/or local animal feeding practices, laboratory comparisons are needed to determine which assays are best suited for implementation. We describe the performance characterization of two end-point PCR assays (CF128 and CF193) and five real-time quantitative PCR (qPCR) assays (Rum2Bac, BacR, BacCow, CowM2, and CowM3) reported to be associated with either ruminant or cattle feces. Each assay was tested against a blinded set of 38 reference challenge filters (19 duplicate samples) containing fecal pollution from 12 different sources suspected to impact water quality. The abundance of each host-associated genetic marker was measured for qPCR-based assays in both target and non-target animals and compared to quantities of total DNA mass, wet mass of fecal material, as well as Bacteroidales, and enterococci determined by 16S rRNA qPCR and culture-based approaches (enterococci only). Ruminant- and cow-associated genetic markers were detected in all filters containing a cattle fecal source. However, some assays cross-reacted with non-target pollution sources. A large amount of variability was evident across laboratories when protocols were not fixed suggesting that protocol standardization will be necessary for widespread implementation. Finally, performance metrics indicate that the cattle-associated CowM2 qPCR method combined with either the BacR or Rum2Bac ruminant-associated methods are most suitable for implementation.     

Personality domains and traits that predict self-reported aberrant driving behaviours in a southeastern US university sample

Personality traits are meaningful predictors of many significant life outcomes, including mortality. Several studies have investigated the relationship between specific personality traits and driving behaviours, e.g., aggression and speeding, in an attempt to identify traits associated with elevated crash risk. These studies, while valuable, are limited in that they examine only a narrow range of personality constructs and thus do not necessarily reveal which traits in constellation best predict aberrant driving behaviours. The primary aim of this study was to use a comprehensive measure of personality to investigate which personality traits are most predictive of four types of aberrant driving behaviour (Aggressive Violations, Ordinary Violations, Errors, Lapses) as indicated by the Manchester Driver Behaviour Questionnaire (DBQ). We recruited 285 young adults (67% female) from a university in the southeastern US. They completed self-report questionnaires including the DBQ and the Personality Inventory for DSM-5, which indexes 5 broad personality domains (Antagonism, Detachment, Disinhibition, Negative Affectivity, Psychoticism) and 25 specific trait facets. Confirmatory factor analysis showed adequate evidence for the DBQ internal structure. Structural regression analyses revealed that the personality domains of Antagonism and Negative Affectivity best predicted both Aggressive Violations and Ordinary Violations, whereas the best predictors of both Errors and Lapses were Negative Affectivity, Disinhibition and to a lesser extent Antagonism. A more nuanced analysis of trait facets revealed that Hostility was the best predictor of Aggressive Violations; Risk-taking and Hostility of Ordinary Violations; Irresponsibility, Separation Insecurity and Attention Seeking of Errors; and Perseveration and Irresponsibility of Lapses.     

Modelling stripe formation in zebrafish: an agent-based approach

Zebrafish have distinctive black stripes and yellow interstripes that form owing to the interaction of different pigment cells. We present a two-population agent-based model for the development and regeneration of these stripes and interstripes informed by recent experimental results. Our model describes stripe pattern formation, laser ablation and mutations. We find that fish growth shortens the necessary scale for long-range interactions and that iridophores, a third type of pigment cell, help align stripes and interstripes.     

Fecal indicator bacteria and Salmonella in ponds managed as bird habitat, San Francisco Bay, California, USA

Throughout the world, coastal resource managers are encouraging the restoration of previously modified coastal habitats back into wetlands and managed ponds for their ecosystem value. Because many coastal wetlands are adjacent to urban centers and waters used for human recreation, it is important to understand how wildlife can affect water quality. We measured fecal indicator bacteria (FIB) concentrations, presence/absence of Salmonella, bird abundance, and physico-chemical parameters in two coastal, managed ponds and adjacent sloughs for 4 weeks during the summer and winter in 2006. We characterized the microbial water quality in these waters relative to state water-quality standards and examined the relationship between FIB, bird abundance, and physico-chemical parameters. A box model approach was utilized to determine the net source or sink of FIB in the ponds during the study periods. FIB concentrations often exceeded state standards, particularly in the summer, and microbial water quality in the sloughs was generally lower than in ponds during both seasons. Specifically, the inflow of water from the sloughs to the ponds during the summer, more so than waterfowl use, appeared to increase the FIB concentrations in the ponds. The box model results suggested that the ponds served as net wetland sources and sinks for FIB, and high bird abundances in the winter likely contributed to net winter source terms for two of the three FIB in both ponds. Eight serovars of the human pathogen Salmonella were isolated from slough and pond waters, although the source of the pathogen to these wetlands was not identified. Thus, it appeared that factors other than bird abundance were most important in modulating FIB concentrations in these ponds.     

In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel

The present study aimed to evaluate in situ the effect of CO₂ laser irradiation to control the progression of enamel erosive lesions. Fifty‐six slabs of bovine incisors enamel (5 × 3 × 2.5 mm³) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO₂ laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO₂ laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2‐day lead‐in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross‐over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three‐way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO₂ laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO₂ laser irradiation was performed. There was no difference in enamel wear between specimens CO₂‐laser irradiated and non‐irradiated (P = 0.513). Under intraoral conditions, CO₂ laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. Microsc. Res. Tech. 77:586–593, 2014. © 2014 Wiley Periodicals, Inc.