Pseudomonas putida and Pseudomonas fluorescens Species Group Recovery from Human Homes Varies Seasonally and by Environment

By shedding light on variation in time as well as in space, long-term biogeographic studies can help us define organisms’ distribution patterns and understand their underlying drivers. Here we examine distributions of Pseudomonas in and around 15 human homes, focusing on the P. putida and P. fluorescens species groups. We describe recovery from 10,941 samples collected during up to 8 visits per home, occurring on average 2.6 times per year. We collected a mean of 141 samples per visit, from sites in most rooms of the house, from the surrounding yards, and from human and pet occupants. We recovered Pseudomonas in 9.7% of samples, with the majority of isolates being from the P. putida and P. fluorescens species groups (approximately 62% and 23% of Pseudomonas samples recovered respectively). Although representatives of both groups were recovered from every season, every house, and every type of environment sampled, recovery was highly variable across houses and samplings. Whereas recovery of P. putida group was higher in summer and fall than in winter and spring, P. fluorescens group isolates were most often recovered in spring. P. putida group recovery from soils was substantially higher than its recovery from all other environment types, while higher P. fluorescens group recovery from soils than from other sites was much less pronounced. Both species groups were recovered from skin and upper respiratory tract samples from healthy humans and pets, although this occurred infrequently. This study indicates that even species that are able to survive under a broad range of conditions can be rare and variable in their distributions in space and in time. For such groups, determining patterns and causes of stochastic and seasonal variability may be more important for understanding the processes driving their biogeography than the identity of the types of environments in which they can be found.     

Association between Mindfulness and Weight Status in a General Population from the NutriNet-Santé Study

Background

Mindfulness is defined as non-judgmental awareness of the present moment. There is some evidence of the efficacy of mindfulness-based interventions in weight loss. However, this psychological concept has only been rarely explored in observational studies, and no study to date has examined the association between dispositional mindfulness and weight status in a large population-based sample.

Objective

We aimed to examine the relationship between mindfulness scores and weight status in a large sample of the adult general population in France.

Design and Methods

A total of 14,400 men and 49,228 women aged ≥18 y participating in the NutriNet-Santé study were included in this cross-sectional analysis. We collected mindfulness data using the Five Facet Mindfulness Questionnaire as well as self-reported weight and height. The association between weight status and dispositional mindfulness, as well as its subscales (observing, describing, acting with awareness, non-judging and non-reactivity), was assessed using multinomial logistic regression models adjusted for socio-demographic and lifestyle factors.

Results

Women with higher dispositional mindfulness scores were less likely to be overweight (excluding obesity) (OR quartile 4 vs. 1 = 0.84, 95% CI: 0.79-0.90) and obese (OR quartile 4 vs. 1 = 0.71, 95% CI: 0.65-0.78). In addition, overall, in this group, all subscales were inversely associated with weight status, with the strongest association found for the “observing” subscale. In men, higher mindfulness was associated only with lower odds of obesity (OR quartile 4 vs. 1 = 0.81 (0.69, 0.96)), and only the “observing” and “non-reactivity” subscales were significantly inversely associated with weight status.

Conclusion

Results support the interest of a shift in perspective that takes into account positive psychological and cognitive factors such as dispositional mindfulness in the investigation of obesity and its associated factors.     

Exploration of the Canyon-Incised Continental Margin of the Northeastern United States Reveals Dynamic Habitats and Diverse Communities

The continental margin off the northeastern United States (NEUS) contains numerous, topographically complex features that increase habitat heterogeneity across the region. However, the majority of these rugged features have never been surveyed, particularly using direct observations. During summer 2013, 31 Remotely-Operated Vehicle (ROV) dives were conducted from 494 to 3271 m depth across a variety of seafloor features to document communities and to infer geological processes that produced such features. The ROV surveyed six broad-scale habitat features, consisting of shelf-breaching canyons, slope-sourced canyons, inter-canyon areas, open-slope/landslide-scar areas, hydrocarbon seeps, and Mytilus Seamount. Four previously unknown chemosynthetic communities dominated by Bathymodiolus mussels were documented. Seafloor methane hydrate was observed at two seep sites. Multivariate analyses indicated that depth and broad-scale habitat significantly influenced megafaunal coral (58 taxa), demersal fish (69 taxa), and decapod crustacean (34 taxa) assemblages. Species richness of fishes and crustaceans significantly declined with depth, while there was no relationship between coral richness and depth. Turnover in assemblage structure occurred on the middle to lower slope at the approximate boundaries of water masses found previously in the region. Coral species richness was also an important variable explaining variation in fish and crustacean assemblages. Coral diversity may serve as an indicator of habitat suitability and variation in available niche diversity for these taxonomic groups. Our surveys added 24 putative coral species and three fishes to the known regional fauna, including the black coral Telopathes magna, the octocoral Metallogorgia melanotrichos and the fishes Gaidropsarus argentatus, Guttigadus latifrons, and Lepidion guentheri. Marine litter was observed on 81% of the dives, with at least 12 coral colonies entangled in debris. While initial exploration revealed the NEUS region to be both geologically dynamic and biologically diverse, further research into the abiotic conditions and the biotic interactions that influence species abundance and distribution is needed.     

How tropomyosin regulates lamellipodial actin‐based motility: a combined biochemical and reconstituted motility approach

At the leading edge of migrating cells, protrusive forces are developed by the assembly of actin filaments organised in a lamellipodial dendritic array at the front and a more distal lamellar linear array. Whether these two arrays are distinct or functionally linked and how they contribute to cell migration is an open issue. Tropomyosin severely inhibits lamellipodium formation and facilitates the lamellar array while enhancing migration, by a mechanism that is not understood. Here we show that the complex in vivo effects of tropomyosin are recapitulated in the reconstituted propulsion of neural Wiskott–Aldrich syndrome protein (N‐WASP)‐functionalised beads, which is based on the sole formation of a dendritic array of actin‐related protein (Arp)2/3‐branched filaments. Actin‐depolymerising factor (ADF) and tropomyosin control the length of the actin tail. By competing with Arp2/3 during filament branching, tropomyosin displays opposite effects on propulsion depending on the surface density of N‐WASP. Tropomyosin binding to the dendritic array is facilitated following filament debranching, causing its enrichment at the rear of the actin tail, like in vivo. These results unveil the mechanism by which tropomyosin generates two morphologically and dynamically segregated actin networks from a single one.     

Use of zoospore concentrations and life cycle parameters in determining the population of anaerobic fungi in the rumen ecosystem

An indirect approach to quantification of the fibrolytic anaerobic fungi in the rumen is described. A mathematical model of the life cycle of anaerobic fungi, based upon observations of the life histories and growth kinetics of these organisms in vitro and in vivo, is constructed and solved in the steady-state to determine the population of particle-attached (substrate-associated) fungal thalli from the concentration of free-swimming zoospores in rumen liquid. The values obtained are broadly consistent with ruminal observations and with observations on faecal populations, which assume that a significant proportion of fungi leaving the rumen (as cysts or spores) can ultimately be accounted for in the faeces.     

HOLARCTIC PHYLOGEOGRAPHY OF AN ASEXUAL SPECIES COMPLEX I. MITOCHONDRIAL DNA VARIATION IN ARCTIC DAPHNIA

Pleistocene glacial cycles undoubtedly altered the evolutionary trajectories of many taxa, yet few studies have examined the impact of such events on genetic differentiation and phylogeography at large geographic scales. Here we present the results of a circumarctic survey of mitochondrial DNA diversity in members of the Daphnia pulex complex. The analysis involved the survey of restriction site polymorphisms in a 2100-bp fragment of the NADH-4 (ND4) and NADH-5 (ND5) genes for 276 populations representing the two major groups (tenebrosa and pulicaria) in this complex across their Holarctic range. A comparison of the distribution patterns for seven clades in this complex revealed very clear phylogeographic structuring. Most notably, pulicaria group lineages were restricted primarily to the Nearctic, with some colonization of formerly glaciated portions of northern Europe. This group was not detected from vast expanses of northern Eurasia, including the Beringian glacial refuge. In contrast, tenebrosa group haplotypes showed considerable intercontinental divergence between Eurasian and North American lineages, but were absent from Greenland and Iceland, as well as the Canadian arctic archipelago. Dispersal in Eurasia was primarily in a westerly direction from Beringia, whereas dispersal in the Nearctic followed proglacial drainage patterns. Long-distance dispersal of certain lineages was observed in both groups, and variation in haplotype richness and nucleotide diversity allowed us to make inferences about the positioning of putative glacial refugia. Overall, the phylogeographic pattern of diversification in this arctic complex is characterized by the apparently unique postglacial histories for each clade, indicating that even closely allied taxa can respond independently to the allopatric effects of glacial cycles. This is in sharp contrast to other phylogeographic studies of species assemblages from more southern (unglaciated) latitudes, which are often characterized by concordant patterns.     

Incidence of deep vein thrombosis related to peripherally inserted central catheters in children and adolescents

Background

Peripherally inserted central catheters (PICC) in children and adolescents are being used with increasing frequency. We sought to determine the incidence and characterize risk factors of deep vein thrombosis associated with peripherally inserted central catheters in a pediatric population.

Methods

We conducted a prospective study involving consecutive patients referred to the radiology department of a tertiary care university-affiliated hospital for insertion of a peripherally inserted central catheter. We included patients aged 18 years or less who weighed more than 2.5 kg and had a peripherally inserted central catheter successfully inserted in his or her arm between June 2004 and November 2005. The primary outcome was the occurrence of partial or complete deep vein thrombosis evaluated by clinical examination, ultrasonography and venous angiography.

Results

A total of 214 patients (101 girls, 113 boys) were included in the study. Partial or complete deep vein thrombosis occurred in 20 patients, for an incidence of 93.5 per 1000 patients and 3.85 per 1000 catheter-days. Only 1 of the cases was symptomatic. In the univariable analyses, the only variable significantly associated with deep vein thrombosis was the presence of factor II mutation G20210A (odds ratio 7.08, 95% confidence interval 1.11–45.15, p = 0.04), a genetic mutation that increases the risk of a blood clot and that was present in 5 (2.3%) of the 214 patients.

Interpretation

The incidence of deep vein thrombosis related to peripherally inserted central catheters in our study was lower than the incidence related to centrally inserted venous catheters described in the pediatric literature (11%–50%).Most data available in the adult and pediatric literature on the incidence of deep vein thrombosis concern centrally inserted venous catheters, which are inserted directly in a central vein (jugular, subclavian or femoral). Typical symptoms of deep vein thrombosis are frequently absent in children and adolescents. Although the diagnosis of deep vein thrombosis is more reliable when based on Doppler ultrasonography or venous angiography,^1–10 in most studies these diagnostic tests were performed only when patients presented clinical symptoms of deep vein thrombosis or catheter dysfunction. In studies focused on the pediatric population, the frequency of deep vein thrombosis related to centrally inserted venous catheters has varied from 11% to 50%.^1,5,6,8,11In the past 10 years, peripherally inserted central catheters (PICC) have been used with increasing frequency in children and adolescents. The catheter is inserted percutaneously via a peripheral vein, with its tip residing in the superior vena cava. The main indications for this type of catheter insertion are difficult venous access, home intravenous antibiotic therapy, administration of chemotherapy or other hyperosmolar solution and long-term parenteral nutrition. The risk of deep vein thrombosis related to peripherally inserted central catheters could be greater among children and adolescents than among adults, given the size of the veins. Several studies have published complications related to peripherally inserted central catheters,^12–20 but few focused on the pediatric population.^13–21 Furthermore, in all of these studies, screening for deep vein thrombosis was not systematic. The real incidence of deep vein thrombosis related to peripherally inserted central catheters and their complications in the pediatric population are therefore unknown. We conducted this study to determine the incidence and characterize the risk factors of deep vein thrombosis related to peripherally inserted central catheters in children and adolescents in our institution.