Intestinal Microbiota Composition of Interleukin-10 Deficient C57BL/6J Mice and Susceptibility to Helicobacter hepaticus-Induced Colitis

The mouse pathobiont Helicobacter hepaticus can induce typhlocolitis in interleukin-10-deficient mice, and H. hepaticus infection of immunodeficient mice is widely used as a model to study the role of pathogens and commensal bacteria in the pathogenesis of inflammatory bowel disease. C57BL/6J Il10^−/− mice kept under specific pathogen-free conditions in two different facilities (MHH and MIT), displayed strong differences with respect to their susceptibilities to H. hepaticus-induced intestinal pathology. Mice at MIT developed robust typhlocolitis after infection with H. hepaticus, while mice at MHH developed no significant pathology after infection with the same H. hepaticus strain. We hypothesized that the intestinal microbiota might be responsible for these differences and therefore performed high resolution analysis of the intestinal microbiota composition in uninfected mice from the two facilities by deep sequencing of partial 16S rRNA amplicons. The microbiota composition differed markedly between mice from both facilities. Significant differences were also detected between two groups of MHH mice born in different years. Of the 119 operational taxonomic units (OTUs) that occurred in at least half the cecum or colon samples of at least one mouse group, 24 were only found in MIT mice, and another 13 OTUs could only be found in MHH samples. While most of the MHH-specific OTUs could only be identified to class or family level, the MIT-specific set contained OTUs identified to genus or species level, including the opportunistic pathogen, Bilophila wadsworthia. The susceptibility to H. hepaticus-induced colitis differed considerably between Il10^−/− mice originating from the two institutions. This was associated with significant differences in microbiota composition, highlighting the importance of characterizing the intestinal microbiome when studying murine models of IBD.     

Pattern of Social Interactions after Group Integration: A Possibility to Keep Stallions in Group

Horses are often kept in individual stables, rather than in outdoor groups, despite such housing system fulfilling many of their welfare needs, such as the access to social partners. Keeping domestic stallions in outdoor groups would mimic bachelor bands that are found in the wild. Unfortunately, the high level of aggression that unfamiliar stallions display when they first encounter each other discourages owners from keeping them in groups. However, this level of aggression is likely to be particularly important only during group integration, when the dominance hierarchy is being established, whereas relatively low aggression rates have been observed among stable feral bachelor bands. We investigated the possibility of housing breeding stallions owned by the Swiss National Stud in groups on a large pasture (5 stallions in 2009 and 8 stallions in 2010). We studied the pattern of agonistic, ritual and affiliative interactions after group integration (17–23 days), and the factors influencing these interactions (time after group integration, dominance rank, age or experience of group housing). We found that stallions displayed generally more ritual than agonistic and than affiliative interactions. The frequency of agonistic and ritual interactions decreased quickly within the first three to four days. The frequency of affiliative interactions increased slowly with time before decreasing after 9–14 days. A stable hierarchy could be measured after 2–3 months. The highest-ranking males had less ritual interactions than the lowest-ranking. Males had also less agonistic, ritual and affiliative interactions if they had already been housed in a group the previous year. Therefore, we found that breeding stallions could be housed together on a large pasture, because the frequency of agonistic interactions decreased quickly and remained at a minimal level from the fourth day following group integration. This housing system could potentially increase horse welfare and reduce labour associated with horse management.     

Endothelium Dependent Vasomotion and In Vitro Markers of Endothelial Repair in Patients with Severe Sepsis: An Observational Study

Background

Outcome in sepsis is mainly defined by the degree of organ failure, for which endothelial dysfunction at the macro- and microvascular level is an important determinant. In this study we evaluated endothelial function in patients with severe sepsis using cellular endothelial markers and in vivo assessment of reactive hyperaemia.

Materials and Methods

Patients with severe sepsis (n = 30) and 15 age- and gender- matched healthy volunteers were included in this study. Using flow cytometry, CD34+/KDR+ endothelial progenitor cells (EPC), CD31+ T-cells, and CD31+/CD42b- endothelial microparticles (EMP) were enumerated. Migratory capacity of cultured circulating angiogenic cells (CAC) was assessed in vitro. Endothelial function was determined using peripheral arterial tonometry at the fingertip.

Results

In patients with severe sepsis, a lower number of EPC, CD31+ T-cells and a decreased migratory capacity of CAC coincided with a blunted reactive hyperaemia response compared to healthy subjects. The number of EMP, on the other hand, did not differ. The presence of organ failure at admission (SOFA score) was inversely related with the number of CD31+ T-cells. Furthermore, the number of EPC at admission was decreased in patients with progressive organ failure within the first week.

Conclusion

In patients with severe sepsis, in vivo measured endothelial dysfunction coincides with lower numbers and reduced function of circulating cells implicated in endothelial repair. Our results suggest that cellular markers of endothelial repair might be valuable in the assessment and evolution of organ dysfunction.     

Sustained Reduction of the Dengue Vector Population Resulting from an Integrated Control Strategy Applied in Two Brazilian Cities

Aedes aegypti has developed evolution-driven adaptations for surviving in the domestic human habitat. Several trap models have been designed considering these strategies and tested for monitoring this efficient vector of Dengue. Here, we report a real-scale evaluation of a system for monitoring and controlling mosquito populations based on egg sampling coupled with geographic information systems technology. The SMCP-Aedes, a system based on open technology and open data standards, was set up from March/2008 to October/2011 as a pilot trial in two sites of Pernambuco -Brazil: Ipojuca (10,000 residents) and Santa Cruz (83,000), in a joint effort of health authorities and staff, and a network of scientists providing scientific support. A widespread infestation by Aedes was found in both sites in 2008–2009, with 96.8%–100% trap positivity. Egg densities were markedly higher in SCC than in Ipojuca. A 90% decrease in egg density was recorded in SCC after two years of sustained control pressure imposed by suppression of >7,500,000 eggs and >3,200 adults, plus larval control by adding fishes to cisterns. In Ipojuca, 1.1 million mosquito eggs were suppressed and a 77% reduction in egg density was achieved. This study aimed at assessing the applicability of a system using GIS and spatial statistic analysis tools for quantitative assessment of mosquito populations. It also provided useful information on the requirements for reducing well-established mosquito populations. Results from two cities led us to conclude that the success in markedly reducing an Aedes population required the appropriate choice of control measures for sustained mass elimination guided by a user-friendly mosquito surveillance system. The system was able to support interventional decisions and to assess the program’s success. Additionally, it created a stimulating environment for health staff and residents, which had a positive impact on their commitment to the dengue control program.     

The Pneumatron: An automated pneumatic apparatus for estimating xylem vulnerability to embolism at high temporal resolution

Xylem vulnerability to embolism represents an important trait to determine species distribution patterns and drought resistance. However, estimating embolism resistance frequently requires time-consuming and ambiguous hydraulic lab measurements. Based on a recently developed pneumatic method, we present and test the “Pneumatron”, a device that generates high time-resolution and fully automated vulnerability curves. Embolism resistance is estimated by applying a partial vacuum to extract air from an excised xylem sample, while monitoring the pressure change over time. Although the amount of gas extracted is strongly correlated with the percentage loss of xylem conductivity, validation of the Pneumatron was performed by comparison with the optical method for Eucalyptus camaldulensis leaves. The Pneumatron improved the precision of the pneumatic method considerably, facilitating the detection of small differences in the (percentage of air discharged [PAD] < 0.47%). Hence, the Pneumatron can directly measure the 50% PAD without any fitting of vulnerability curves. PAD and embolism frequency based on the optical method were strongly correlated (r² = 0.93) for E. camaldulensis. By providing an open source platform, the Pneumatron represents an easy, low-cost, and powerful tool for field measurements, which can significantly improve our understanding of plant–water relations and the mechanisms behind embolism.     

Drought effects on resource partition and conservation among leaf ontogenetic stages in epiphytic tank bromeliads

Studying the response to drought stress of keystone epiphytes such as tank bromeliads is essential to better understand their resistance capacity to future climate change. The objective was to test whether there is any variation in the carbon, water and nutrient status among different leaf ontogenetic stages in a bromeliad rosette subjected to a gradient of drought stress. We used a semi-controlled experiment consisting in a gradient of water shortage in Aechmea aquilega and Lutheria splendens. For each bromeliad and drought treatment, three leaves were collected based on their position in the rosette and several functional traits related to water and nutrient status, and carbon metabolism were measured. We found that water status traits (relative water content, leaf succulence, osmotic and midday water potentials) and carbon metabolism traits (carbon assimilation, maximum quantum yield of photosystem II, chlorophyll and starch contents) decreased with increasing drought stress, while leaf soluble sugars and carbon, nitrogen and phosphorus contents remained unchanged. The different leaf ontogenetic stages showed only marginal variations when subjected to a gradient of drought. Resources were not reallocated between different leaf ontogenetic stages but we found a reallocation of soluble sugars from leaf starch reserves to the root system. Both species were capable of metabolic and physiological adjustments in response to drought. Overall, this study advances our understanding of the resistance of bromeliads faced with increasing drought stress and paves the way for in-depth reflection on their strategies to cope with water shortage.     

Letter to the Editor—the Use of Micronucleus Assay on Buccal Mucosa Cells for Risk Assessment: Relevance of Cigarette Smoke and Cytogenotoxicity

Biological Trace Element Research -     

Current genetic engineering strategies for the production of antihypertensive ACEI peptides

Hypertension is a major and highly prevalent risk factor for various diseases. Among the most frequently prescribed antihypertensive first-line drugs are synthetic angiotensin I-converting enzyme inhibitors (ACEI). However, since  their use in hypertension therapy has been linked to various side effects, interest in the application of food-derived ACEI peptides (ACEIp) as antihypertensive agents is rapidly growing. Although promising, the industrial production of ACEIp through conventional methods such as chemical synthesis or enzymatic hydrolysis of food proteins has been proven troublesome. We here provide an overview of current antihypertensive therapeutics, focusing on ACEI, and illustrate how biotechnology and bioengineering can overcome the limitations of ACEIp large-scale production. Latest advances in ACEIp research and current genetic engineering-based strategies for heterologous production of ACEIp (and precursors) are also presented. Cloning approaches include tandem repeats of single ACEIp, ACEIp fusion to proteins/polypeptides, joining multivariate ACEIp into bioactive polypeptides, and producing ACEIp-containing modified plant storage proteins. Although bacteria have been privileged ACEIp heterologous hosts, particularly when testing for new genetic engineering strategies, plants and microalgae-based platforms are now emerging. Besides being generally safer, cost-effective and scalable, these “pharming” platforms can perform therelevant posttranslational modifications and produce (and eventually deliver) biologically active protein/peptide-based antihypertensive medicines.     

Seed dispersal networks in tropical forest fragments: Area effects,remnant species,and interaction diversity

Seed dispersal interactions involve key ecological processes in tropical forests that help to maintain ecosystem functioning. Yet this functionality may be threatened by increasing habitat loss, defaunation, and fragmentation. However, generalist species, and their interactions, can benefit from the habitat change caused by human disturbance while more specialized interactions mostly disappear. Therefore, changes in the structure of the local, within fragment, networks can be expected. Here we investigated how the structure of seed dispersal networks changes along a gradient of increasing habitat fragmentation. We analyzed 16 bird seed dispersal assemblages from forest fragments of a biodiversity-rich ecosystem. We found significant species–, interaction–, and network–area relationships, yet the later was determined by the number of species remaining in each community. The number of frugivorous bird and plant species, their interactions, and the number of links per species decreases as area is lost in the fragmented landscape. In contrast, network nestedness has a negative relationship with fragment area, suggesting an increasing generalization of the network structure in the gradient of fragmentation. Network specialization was not significantly affected by area, indicating that some network properties may be invariant to disturbance. Still, the local extinction of partner species, paralleled by a loss of interactions and specialist–specialist bird–plant seed dispersal associations, suggests the functional homogenization of the system as area is lost. Our study provides empirical evidence for network–area relationships driven by the presence/absence of remnant species and the interactions they perform.