Contemporary pollen-mediated gene immigration reflects the historical isolation of a rare,animal-pollinated shrub in a fragmented landscape

Fragmentation is generally considered to have negative impacts on widespread outbreedersbut impacts on gene flow and diversity in patchy, naturally rare, self-compatible plantspecies remain unclear. We investigated diversity, gene flow and contemporarypollen-mediated gene immigration in the rare, narrowly distributed endemic shrubCalothamnus quadrifidus ssp. teretifolius. This taxon occurs in aninternationally recognized biodiversity hotspot subjected to recent human-inducedfragmentation and the condition of the remnants ranges from intact to highly degraded.Using microsatellites, we found that inbreeding, historically low gene flow andsignificant population differentiation have characterized the genetic system of C.quadrifidus ssp. teretifolius. Inbreeding arises from self-pollination, asmall amount of biparental inbreeding and significant correlation of outcross paternitybut fecundity was high suggesting populations might have purged their lethals. Paternityanalyses show that pollinators can move pollen over degraded and intact habitat butpopulations in both intact and degraded remnants had few pollen parents per seed parentand low pollen immigration. Genetic diversity did not differ significantly between intactand degraded remnants but there were signs of genetic bottlenecks and reduced diversity insome degraded remnants. Overall, our study suggests human-induced fragmentation has notsignificantly changed the mating system, or pollen immigration to, remnant populations andtherefore genetic connectivity need not be the highest conservation priority. Rather, forrare species adapted to higher levels of inbreeding, conservation efforts may be bestdirected to managing intact habitats and ecosystem processes.     

Mutant EL-4 thymoma cells polyclonally activate murine and human B cells via direct cell interaction

In this report we show that three mutagenized sublines of (murine) EL-4 thymoma cells can constitutively activate human and/or murine B cells via an MHC-nonrestricted cell-cell interaction. The activation signal is not by itself mitogenic but renders B cells capable of proliferating in response to interleukin 2 (IL 2). In addition, one of the mutant EL-4 sublines can constitutively respond by release of IL 2 in the presence of IL 1-containing macrophage (P388D1) supernatant. The exact relationships between these functional properties of the mutant EL-4 thymoma cells and those associated with activated normal T helper-cells remain to be established. However, the EL-4 cells provide a unique system to study in parallel murine and human B cell responses. In particular, the following observations were made during the present study. First, anti-Ig antibodies (anti-Ig) were required for B cell activation in conjunction with two EL-4 sublines acting only on murine B cells, whereas with a third subline acting on both murine and human B cells, anti-Ig was not required. Anti-Ig by itself did not lead to significant B cell activation in the absence of mutant EL-4 (or normal T) cells. Second, the growth factor-stimulated proliferation of EL-4-activated B cells, following separation of the B cells from the EL-4 cells, lasted only 2 days. These results, thus, indicate that the requirement for a surface Ig-mediated B cell activation signal depends on the quality/intensity of a direct T cell signal and that cell-cell interactions may exert a more stringent control over the growth factor responsiveness of B cells as compared with T cells.     

Demonstration of steroid 17 alpha-hydroxylase activity in human fetal kidney, thymus, and spleen

In previous investigations, steroid 21-hydroxylase activity was demonstrated in human fetal kidney, thymus, and spleen tissues. In the present investigation, steroid 17 alpha-hydroxylase activity also was found in microsome-enriched preparations of human fetal kidney, thymus, and spleen tissues.     

Homeoviscous theory under pressure: II. The molecular order of membranes from deep-sea fish

The molecular order of brain and liver membranes isolated from deep sea and continental shelf fish species have been estimated and compared using the fluorescence polarization technique in order to determine whether life in a high pressure habitat is associated with an adjustment of membrane order. Fish were trawled at depths between 200 m and 4000 m, liver and brain membranes were fractionated, and fluorescence polarization was measured at 4°C and ambient pressure. Polarization of the brain myelin fraction provided a statistically significant regression with depth of capture ($\text{P<0.001}$) with a slope of ?0.004 km^?1. This change in polarization with depth was sufficient to offset approximately half of the pressure-induced increase in polarization and thus represents the first structural evidence of homeoviscous adaptation to pressure. Polarization of the brain synaptic and liver mitochondrial fraction was not significantly related to depth. This may be due, at least in part, to a high individual variability of polarization compared to laboratory-acclimated freshwater fish.     

Fish hypnosis: Induction of an atonic immobility reflex

An immobility reflex may be induced in fish by a vigorous flow of water through the branchial chamber. The reflex was observed in 22 species representing bony and cartilaginous fishes from diverse habitats, and was invariably characterised by loss of caudal muscle tone and limp posture. The immobilised state may be maintained for many hours, and revival is instantaneous. The critical flow rate for induction increases with increasing body size in the snapper, Pagrus auratus, and heart rate falls below the resting rate. In addition, haematological parameters, and plasma lactate after 6?h were typical of resting fish. Although the mechanism is unclear, and the selective advantage for the fish unknown, pressure-sensitive receptors in the branchial chamber are likely to be involved. Application in live fish transport, and recovery from handling and exercise stressors is suggested.     

Human Chorionic Gonadotropin Increases β-Cleavage of Amyloid Precursor Protein in SH-SY5Y Cells

Elevated levels of amyloid-β (Aβ) peptides, the main component of amyloid plaques in Alzheimer’s disease, are the result of excessive β- and γ-cleavage of the amyloid precursor protein (APP) and/or impaired Aβ clearance in the brain. It has been suggested that high concentrations of luteinizing hormone (LH) in women contribute to increased Aβ generation after menopause, but the mechanism for this is incompletely understood. We investigated the effect of human chorionic gonadotropin (hCG), an LH receptor agonist, on APP β-cleavage in the SH-SY5Y neuroblastoma cell line. Treatment of these cells with hCG-induced elevated β-cleavage in a dose-dependent manner: administration of 30 mIU but not 10 mIU/ml of hCG significantly increased sAPPβ levels in the cell medium 1.7-fold as measured by ELISA. These results support the notion that LH contributes to elevated Aβ levels at least in part by increasing β-cleavage of APP by β-site APP cleaving enzyme.     

Medical and Household Characteristics Associated with Methicillin Resistant Staphylococcus aureus Nasal Carriage among Patients Admitted to a Rural Tertiary Care Hospital

Background

Methicillin resistant Staphylococcus aureus (MRSA) poses a threat to patient safety and public health. Understanding how MRSA is acquired is important for prevention efforts. This study investigates risk factors for MRSA nasal carriage among patients at an eastern North Carolina hospital in 2011.

Methods

Using a case-control design, hospitalized patients ages 18 – 65 years were enrolled between July 25, 2011 and December 15, 2011 at Vidant Medical Center, a tertiary care hospital that screens all admitted patients for nasal MRSA carriage. Cases, defined as MRSA nasal carriers, were age and gender matched to controls, non-MRSA carriers. In-hospital interviews were conducted, and medical records were reviewed to obtain information on medical and household exposures. Multivariable conditional logistic regression was used to derive odds ratio (OR) estimates of association between MRSA carriage and medical and household exposures.

Results

In total, 117 cases and 119 controls were recruited to participate. Risk factors for MRSA carriage included having household members who took antibiotics or were hospitalized (OR: 3.27; 95% Confidence Interval (CI): 1.24–8.57) and prior hospitalization with a positive MRSA screen (OR: 3.21; 95% CI: 1.12–9.23). A lower proportion of cases than controls were previously hospitalized without a past positive MRSA screen (OR: 0.40; 95% CI: 0.19–0.87).

Conclusion

These findings suggest that household exposures are important determinants of MRSA nasal carriage in hospitalized patients screened at admission.     

Deaths and Medical Visits Attributable to Environmental Pollution in the United Arab Emirates

Background

This study estimates the potential health gains achievable in the United Arab Emirates (UAE) with improved controls on environmental pollution. The UAE is an emerging economy in which population health risks have shifted rapidly from infectious diseases to chronic conditions observed in developed nations. The UAE government commissioned this work as part of an environmental health strategic planning project intended to address this shift in the nature of the country’s disease burden.

Methods and Findings

We assessed the burden of disease attributable to six environmental exposure routes outdoor air, indoor air, drinking water, coastal water, occupational environments, and climate change. For every exposure route, we integrated UAE environmental monitoring and public health data in a spatially resolved Monte Carlo simulation model to estimate the annual disease burden attributable to selected pollutants. The assessment included the entire UAE population (4.5 million for the year of analysis). The study found that outdoor air pollution was the leading contributor to mortality, with 651 attributable deaths (95% confidence interval [CI] 143–1,440), or 7.3% of all deaths. Indoor air pollution and occupational exposures were the second and third leading contributors to mortality, with 153 (95% CI 85–216) and 46 attributable deaths (95% CI 26–72), respectively. The leading contributor to health-care facility visits was drinking water pollution, to which 46,600 (95% CI 15,300–61,400) health-care facility visits were attributed (about 15% of the visits for all the diseases considered in this study). Major study limitations included (1) a lack of information needed to translate health-care facility visits to quality-adjusted-life-year estimates and (2) insufficient spatial coverage of environmental data.

Conclusions

Based on international comparisons, the UAE’s environmental disease burden is low for all factors except outdoor air pollution. From a public health perspective, reducing pollutant emissions to outdoor air should be a high priority for the UAE’s environmental agencies.