Iron Acquisition Mechanisms and Their Role in the Virulence of Burkholderia Species

Burkholderia is a genus within the β-Proteobacteriaceae that contains at least 90 validly named species which can be found in a diverse range of environments. A number of pathogenic species occur within the genus. These include Burkholderia cenocepacia and Burkholderia multivorans, opportunistic pathogens that can infect the lungs of patients with cystic fibrosis, and are members of the Burkholderia cepacia complex (Bcc). Burkholderia pseudomallei is also an opportunistic pathogen, but in contrast to Bcc species it causes the tropical human disease melioidosis, while its close relative Burkholderia mallei is the causative agent of glanders in horses. For these pathogens to survive within a host and cause disease they must be able to acquire iron. This chemical element is essential for nearly all living organisms due to its important role in many enzymes and metabolic processes. In the mammalian host, the amount of accessible free iron is negligible due to the low solubility of the metal ion in its higher oxidation state and the tight binding of this element by host proteins such as ferritin and lactoferrin. As with other pathogenic bacteria, Burkholderia species have evolved an array of iron acquisition mechanisms with which to capture iron from the host environment. These mechanisms include the production and utilization of siderophores and the possession of a haem uptake system. Here, we summarize the known mechanisms of iron acquisition in pathogenic Burkholderia species and discuss the evidence for their importance in the context of virulence and the establishment of infection in the host. We have also carried out an extensive bioinformatic analysis to identify which siderophores are produced by each Burkholderia species that is pathogenic to humans

Inter-ethnic relations among black students at a South African higher education institution

This study explored the inter-ethnic relations and experiences of students at a higher education institution, using an exploratory case study approach. Purposive sampling was used to select students belonging to black South African ethnic groups. Semi-structured interviews were used to collect data from three participants; interpretative phenomenological analysis was used for analysis. The themes extracted were ethnic identity: identity confusion vs. certainty; personal experiences of inter-ethnic relations; and majority and minority ethnic groups’ experiences. Identity salience was found to not particularly be integral to the cultivation of inter-ethnic relations. Moreover, participants’ inter-ethnic experiences were varied; some were positive, and others, negative. Relations between majority and minority ethnic groups are seemingly supported by existing literature, as majority ethnic group members typically initiated negative interactions, more so than did minority ethnic groups. Future studies should interrogate inter-ethnic dynamics on a broader scale, and explore ethnic bullying and its impact on inter-ethnic relations

Dietary inclusion of ensiled avocado oil cake affects growth, nutrient digestion, and carcass characteristics of pigs

In this experiment, the effects were evaluated of various dietary inclusion levels of avocado oil cake (AOC) silage on growth performance, nutrient digestibility, and carcass characteristics in pigs. A mixture of 70% AOC, 25% wheat bran, and 5% sugarcane molasses was ensiled in 200 L drums for 90 days. It was then incorporated at 0%, 3% and 5% in the experimental diets. Twenty-seven Large White cross Landrace (LW x LR) weaner pigs, with an average live weight of 22 kg, were stratified by weight and randomly allocated to the three experimental diets (9 pigs/diet). Pigs were weighed individually each week throughout the trial. Daily feed intake, average daily gain (ADG) and feed conversion rates (FCRs) were recorded. A nutrient digestibility study was carried out on completion of the growth trial. At the end of the experiment, pigs were fasted for twelve hours and weighed to determine the final weight. The pigs were then slaughtered, and carcass samples were collected and analysed. The growth performance of pigs was not affected by diet, irrespective of fibre levels in the AOC silage. However, the addition of 3% AOC silage improved the digestibility of fibre fractions. The weights of the cold carcass, chops, and backfat thickness were reduced with AOC silage addition

Fijian sea krait behavior relates to fine - scale environmental heterogeneity in old - growth coastal forest: the importance of integrated land – sea management for protecting amphibious animals

The importance of terrestrial coastal ecosystems for maintaining healthy coral reef ecosystems remains understudied. Sea kraits are amphibious snakes that require healthy coral reefs for foraging, but little is known about their requirements of terrestrial habitats, where they slough their skin, digest prey, and breed. Using concurrent microclimate measurements and behavior surveys, we show that a small, topographically flat atoll in Fiji with coastal forest provides many microhabitats that relate to the behaviors of Yellow Lipped Sea Kraits, Laticauda colubrina. Microclimates were significantly related to canopy cover, leaf litter depth, and distance from the high-water mark (HWM). Sea kraits were almost exclusively observed in coastal forest within 30 m of the HWM. Sloughing of skins only occurred within crevices of mature or dying trees. Resting L. colubrina were significantly more likely to occur at locations with higher mean diurnal temperatures, lower leaf litter depths, and shorter distances from the HWM. On Leleuvia, behavior of L. colubrina therefore relates to environmental heterogeneity created by old-growth coastal forests, particularly canopy cover and crevices in mature and dead tree trunks. The importance of healthy coastal habitats, both terrestrial and marine, for L. colubrina suggests it could be a good flagship species for advocating integrated land-sea management. Furthermore, our study highlights the importance of coastal forests and topographically flat atolls for biodiversity conservation. Effective conservation management of amphibious species that utilize land- and seascapes is therefore likely to require a holistic approach that incorporates connectivity among ecosystems and environmental heterogeneity at all relevant scales

Attachment disorders diagnosed by community practitioners:a replication and extension

Background: While considered a rare diagnosis, reactive attachment disorder (RAD) is simultaneously the subject of considerable debate. A recent report suggested that RAD is overdiagnosed in community settings and that conduct problems may be used to make a diagnosis of RAD (Woolgar & Baldock, Child and Adolescent Mental Health, 20, 2015, 34–40). This study seeks to replicate and extend these findings. Method: Clinical assessment data from 100 consecutive admissions of maltreated foster and adopted children (ages 3–17) to a specialty treatment clinic in the United States were reviewed. Measures included semi-structured interviews of RAD and disinhibited social engagement disorder (DSED) symptoms and caregiver-report questionnaires of emotional problems, conduct problems, and the quality of the parent–child relationship. Results: Of the 100 cases reviewed, 39 presented with a diagnostic history of RAD, DSED, or ‘attachment disorder’. Of these cases, three were diagnosed in-clinic with DSED; no cases met diagnostic criteria for RAD according to DSM-5 criteria. However, analyses found that those diagnosed with RAD by community-based clinicians were significantly more likely to display conduct problems and to be adopted (as opposed to in foster care). Conclusions: These findings confirm those of Woolgar and Baldock (Child and Adolescent Mental Health, 20, 2015, 34–40). It appears that the diagnostic criteria of RAD are commonly being inaccurately applied in general community-based practice. Clarification of diagnostic criteria for RAD in recent revisions of diagnostic taxonomies, the accumulation of empirical data on RAD, and improved instrumentation are either poorly disseminated or inadequately implemented in community-based practice settings

Distinct modes of promoter recognition by two iron starvation σ factors with overlapping promoter specificities

OrbS and PvdS are extracytoplasmic function (ECF) σ factors that regulate transcription of operons required for the biosynthesis of the siderophores ornibactin and pyoverdine in the B. cepacia complex and Pseudomonas spp., respectively. Here we show that promoter recognition by OrbS requires specific tetrameric -35 and -10 element sequences that are strikingly similar to those of the consensus PvdS-dependent promoter. However, whereas P. aeruginosa PvdS can serve OrbS-dependent promoters, OrbS cannot utilise PvdS-dependent promoters. To identify features present at OrbS-dependent promoters that facilitate recognition by OrbS, we carried out a detailed analysis of the nucleotide sequence requirements for promoter recognition by both OrbS and PvdS. This revealed that DNA sequence features located outside of the sigma binding elements are required for efficient promoter utilisation by OrbS. In particular, the presence of an A-tract extending downstream from the -35 element at OrbS-dependent promoters was shown to be an important contributor to OrbS specificity. Our observations demonstrate that the nature of the spacer sequence can have a major impact on promoter recognition by some ECF sigma factors through modulation of the local DNA architecture

Theoretical description of deformed proton emitters: nonadiabatic coupled-channel method

The newly developed nonadiabatic method based on the coupled-channel Schroedinger equation with Gamow states is used to study the phenomenon of proton radioactivity. The new method, adopting the weak coupling regime of the particle-plus-rotor model, allows for the inclusion of excitations in the daughter nucleus. This can lead to rather different predictions for lifetimes and branching ratios as compared to the standard adiabatic approximation corresponding to the strong coupling scheme. Calculations are performed for several experimentally seen, non-spherical nuclei beyond the proton dripline. By comparing theory and experiment, we are able to characterize the angular momentum content of the observed narrow resonance.Comment: 12 pages including 10 figure