Tracking Microbial Contamination in Retail Environments Using Fluorescent Powder - A Retail Delicatessen Environment Example

Cross contamination of foodborne pathogens in the retail environment is a significant public health issue contributing to an increased risk for foodborne illness. Ready-to-eat (RTE) processed foods such as deli meats, cheese, and in some cases fresh produce, have been involved in foodborne disease outbreaks due to contamination with pathogens such as Listeria monocytogenes. With respect to L. monocytogenes, deli slicers are often the main source of cross contamination. The goal of this study was to use a fluorescent compound to simulate bacterial contamination and track this contamination in a retail setting. A mock deli kitchen was designed to simulate the retail environment. Deli meat was inoculated with the fluorescent compound and volunteers were recruited to complete a set of tasks similar to those expected of a food retail employee. The volunteers were instructed to slice, package, and store the meat in a deli refrigerator. The potential cross contamination was tracked in the mock retail environment by swabbing specific areas and measuring the optical density of the swabbed area with a spectrophotometer. The results indicated that the refrigerator (i.e. deli case) grip and various areas on the slicer had the highest risk for cross contamination. The results of this study may be used to develop more focused training material for retail employees. In addition, similar methodologies could also be used to track microbial contamination in food production environments (e.g. small farms), hospitals, nursing homes, cruise ships, and hotels.     

Mitochondrial DNA phylogeography and population history of the grey wolf canis lupus

The grey wolf (Canis lupus) and coyote (C. latrans) are highly mobile carnivores that disperse over great distances in search of territories and mates. Previous genetic studies have shown little geographical structure in either species. However, population genetic structure is also influenced by past isolation events and population fluctuations during glacial periods. In this study, control region sequence data from a worldwide sample of grey wolves and a more limited sample of coyotes were analysed. The results suggest that fluctuating population sizes during the late Pleistocene have left a genetic signature on levels of variation in both species. Genealogical measures of nucleotide diversity suggest that historical population sizes were much larger in both species and grey wolves were more numerous than coyotes. Currently, about 300 000 wolves and 7 million coyotes exist. In grey wolves, genetic diversity is greater than that predicted from census population size, reflecting recent historical population declines. By contrast, nucleotide diversity in coyotes is smaller than that predicted by census population size, reflecting a recent population expansion following the extirpation of wolves from much of North America. Both species show little partitioning of haplotypes on continental or regional scales. However, a statistical parsimony analysis indicates local genetic structure that suggests recent restricted gene flow.     

End-tidal carbon dioxide tension reflects arterial carbon dioxide tension in the heat-stressed human with and without simulated hemorrhage

End-tidal carbon dioxide tension (Pet(CO(2))) is reduced during an orthostatic challenge, during heat stress, and during a combination of these two conditions. The importance of these changes is dependent on Pet(CO(2)) being an accurate surrogate for arterial carbon dioxide tension (Pa(CO(2))), the latter being the physiologically relevant variable. This study tested the hypothesis that Pet(CO(2)) provides an accurate assessment of Pa(CO(2)) during the aforementioned conditions. Comparisons between these measures were made: 1) after two levels of heat stress (N = 11); 2) during combined heat stress and simulated hemorrhage [via lower-body negative pressure (LBNP), N = 8]; and 3) during an end-tidal clamping protocol to attenuate heat stress-induced reductions in Pet(CO(2)) (N = 7). Pet(CO(2)) and Pa(CO(2)) decreased during heat stress (P < 0.001); however, there was no group difference between Pa(CO(2)) and Pet(CO(2)) (P = 0.36) nor was there a significant interaction between thermal condition and measurement technique (P = 0.06). To verify that this nonsignificant trend for the interaction was not due to a type II error, Pet(CO(2)) and Pa(CO(2)) at three distinct thermal conditions were also compared using paired t-tests, revealing no difference between Pa(CO(2)) and Pet(CO(2)) while normothermic (P = 0.14) and following a 1.0 ± 0.2°C (P = 0.21) and 1.4 ± 0.2°C (P = 0.28) increase in internal temperature. During LBNP while heat stressed, measures of Pet(CO(2)) and Pa(CO(2)) were similar (P = 0.61). Likewise, during the end-tidal carbon dioxide clamping protocol, the increases in Pet(CO(2)) (7.5 ± 2.8 mmHg) and Pa(CO(2)) (6.6 ± 3.4 mmHg) were similar (P = 0.31). These data indicate that mean Pet(CO(2)) reflects mean Pa(CO(2)) during the evaluated conditions.     

The mutation rates of di-, tri- and tetranucleotide repeats in Drosophila melanogaster

In a recent study, we reported that the combined average mutation rate of 10 di-, 6 tri-, and 8 tetranucleotide repeats in Drosophila melanogaster was 6.3 x 10(-6) mutations per locus per generation, a rate substantially below that of microsatellite repeat units in mammals studied to date (range = 10(-2)-10(-5) per locus per generation). To obtain a more precise estimate of mutation rate for dinucleotide repeat motifs alone, we assayed 39 new dinucleotide repeat microsatellite loci in the mutation accumulation lines from our earlier study. Our estimate of mutation rate for a total of 49 dinucleotide repeats is 9.3 x 10(-6) per locus per generation, only slightly higher than the estimate from our earlier study. We also estimated the relative difference in microsatellite mutation rate among di-, tri-, and tetranucleotide repeats in the genome of D. melanogaster using a method based on population variation, and we found that tri- and tetranucleotide repeats mutate at rates 6.4 and 8.4 times slower than that of dinucleotide repeats, respectively. The slower mutation rates of tri- and tetranucleotide repeats appear to be associated with a relatively short repeat unit length of these repeat motifs in the genome of D. melanogaster. A positive correlation between repeat unit length and allelic variation suggests that mutation rate increases as the repeat unit lengths of microsatellites increase.      

Fine Structure of the Neogregarine Farinocystis tribolii Weiser, 1953. Developmental Stages in Merogony.

SYNOPSIS. The fine structure of schizonts and free merozoites of the neogregarine Farinocystis tribolii Weiser, and their development in the fat body of larval Tribolium castaneum were studied.
The surface of a multinucleate schizont and that of a uninucleate merozoite is covered by a double-layered membrane. Rhoptries and micronemes are present. The cytoplasm is packed with ribosomes and also contains dark bodies. Mitochondria are of the vesicular type. The spherical nucleus of the schizont and merozoite contains a large nucleolus. The anterior end of the merozoite has a typical conoidal complex composed of a conoid and a polar ring with 22 subpellicular mirotubules projecting from it.
New findings are a membranous septum across the body of the merozoite at 2/3 of its length below the nucleus and a highly osmiophilic spiral structure in the perinuclear space close to the Golgi complex. In addition, we found some "developmental stages" of the latter structure.     

Prediction of the structural response of the femoral shaft under dynamic loading using subject-specific finite element models

The goal of this study was to predict the structural response of the femoral shaft under dynamic loading conditions using subject-specific finite element (SS-FE) models and to evaluate the prediction accuracy of the models in relation to the model complexity. In total, SS-FE models of 31 femur specimens were developed. Using those models, dynamic three-point bending and combined loading tests (bending with four different levels of axial compression) of bare femurs were simulated, and the prediction capabilities of five different levels of model complexity were evaluated based on the impact force time histories: baseline, mass-based scaled, structure-based scaled, geometric SS-FE, and heterogenized SS-FE models. Among the five levels of model complexity, the geometric SS-FE and the heterogenized SS-FE models showed statistically significant improvement on response prediction capability compared to the other model formulations whereas the difference between two SS-FE models was negligible. This result indicated the geometric SS-FE models, containing detailed geometric information from CT images with homogeneous linear isotropic elastic material properties, would be an optimal model complexity for prediction of structural response of the femoral shafts under the dynamic loading conditions. The average and the standard deviation of the RMS errors of the geometric SS-FE models for all the 31 cases was 0.46 kN and 0.66 kN, respectively. This study highlights the contribution of geometric variability on the structural response variation of the femoral shafts subjected to dynamic loading condition and the potential of geometric SS-FE models to capture the structural response variation of the femoral shafts.     

The palatability of flavoured novel floating pellets made with brewer's spent grain to captive carp

Abstract

The palatability to common carp, Cyprinus carpio L. of three newly developed differently flavoured floating pellets made from a high proportion (40%) of brewer's spent grain (BSG) was tested using a multiple-offer feeding experiment. The addition of ‘bold’ flavours, such as vanilla or strawberry essence, may help mask the unpleasant taste of some piscicides; however, their inclusion must not compromise uptake by carp. There were no significant differences between the consumption rates of the three varieties, and all flavours were readily consumed. Therefore, it is suggested that highly flavoured pellets made with BSG have a strong potential to mask the flavour of an unpalatable toxin, and further research is now needed to test this hypothesis.     

Intragenomic variation within ITS1 and ITS2 of freshwater crayfishes (Decapoda: Cambaridae): implications for phylogenetic and microsatellite studies

Intragenomic variation in ITS1 and ITS2 is known to exit but is widely ignored in phylogenetic studies using these gene regions. The amount of variation in seven crayfish species, including three populations of Orconectes luteus and two of Procambarus clarkii, was assessed by sequencing 3, 5, or 10 clones from the same individuals, for a total of 77 sequences. The ITS1 and ITS2 sequences reported here are some of the longest known, with aligned lengths of 760 and 1,300 bp, respectively. They contain multiple microsatellite insertions, all of which show considerable intragenomic variation in the number of repeat elements. This variation is enough to obscure phylogenetic relationships at the population level, although relationships between species can be estimated. Given the hybridization techniques used to locate microsatellites, multiple-copy regions like ITS1 and ITS2 will be preferentially found if they contain microsatellites, and in these cases the microsatellites will not behave as typical Mendelian markers and could give spurious results.     

Effects of environmental salinity on gill endothelin receptor expression in the killifish, Fundulus heteroclitus

We recently determined that rapid changes in environmental salinity alter endothelin-1 (EDN1) mRNA levels in the euryhaline killifish, Fundulus heteroclitus, so we hypothesized that EDN1 may be a local regulator of gill ion transport in teleost fishes. The purpose of the present study was to examine the effects of changes in environmental salinity on the gill endothelin receptors: EDNRA, EDNRB, and EDNRC. Using quantitative real-time PCR, we determined that after a fresh water (FW) to seawater (SW) transfer, there is a two to threefold increase in gill EDNRA and EDNRB mRNA levels. Likewise, we found a two to three fold increase in gill EDNRA and EDNRB protein concentration. In addition, killifish that have acclimated to FW for 30 days had significantly lower EDNRA mRNA and protein levels than SW killifish. ENDRA were immunolocalized to the mitochondrion-rich cells of the killifish gill, suggesting that EDN1 signaling cascades may affect MRC function. EDNRB were found throughout the gill vasculature and on lamellar pillar cells. We previously immunolocalized EDN1 to the pillar cell suggesting that EDN1 acts as an autocrine signaling molecule and potentially regulates pillar cell tone and lamellar perfusion. We conclude that EDN1 is physiologically active in the teleost gill, and regulated by environmental salinity. Future functional studies examining the physiological role of this system are necessary to completely understand EDN1 in the fish gill.