Physiological Adaptations in Response to Environmental Stress During an N2-Fixing Anabaena Bloom

Anabaena spiroides has the ability to maintain intense biomass production for extensive periods in the epilimnion of a small eutrophic lake characterized by conditions shown to cause photooxidative death in a number of other phytoplankton. By the enhancement of carotenoid synthesis chlorophyll a was protected from photooxidation and prevented from catalyzing other photooxidative reactions within the cells. By temporally separating CO₂ and N₂ fixation, maximum utilization of photosynthetically active radiation was achieved. Because CO₂ fixation was more sensitive than N₂ fixation to a high oxygen concentration, the former was maximized during morning hours, before the afternoon buildup of dissolved oxygen. The diurnal partitioning of carbon and N₂ fixation has two additional advantages; possible competition for reductant-generating compounds is minimized, and adequate endogenous pools of carbon skeletons are assured to accept newly fixed ammonia. Hence, Anabaena, far from undergoing photooxidative death, appears to utilize a physiological strategy which allows optimization of radiant energy use for reductive processes and dominance of surface waters and shading of deeper phytoplankton during summer blooms.     

The genetic status and conservation management of two cultivated bulb species extinct in the wild: Tecophilaea cyanocrocus (Chile) and Tulipa sprengeri (Turkey)

Tecophilaea cyanocrocus and Tulipasprengeri are both extinct in the wild as aresult of overharvesting by commercialcollectors. Stocks of both species survive incultivation in amateur collections, commercialnurseries and botanic garden collections.Whilst both species share a similarconservation history, the distribution ofgenetic diversity within cultivated materialwas unknown. To support the long-termconservation of both species the geneticdiversity of the surviving stocks was assessedusing amplified fragment length polymorphisms(AFLPs). This study revealed different geneticstructures for the two bulb species. The Kewcollections of T. cyanocrocus, originallyobtained from a commercial nursery, VanTubergen, are genetically highly uniform andthe addition of samples from other collectionshas dramatically increased the level ofvariation. In contrast, the collections ofT. sprengeri held at Kew since the early20th century include representativegenotypes covering the whole range of geneticvariation found in this species and areprobably the source of all other cultivatedmaterial. The results are discussed in relationto the management of these species to ensuretheir continued survival in cultivation.     

Splice variants of mda-7/IL-24 differentially affect survival and induce apoptosis in U2OS cells

Interleukin-24 (mda-7/IL-24) is a cytokine in the IL-10 family that has received a great deal of attention for its properties as a tumor suppressor and as a potential treatment for cancer. In this study, we have identified and characterized five alternatively spliced isoforms of this gene. Several, but not all of these isoforms induce apoptosis in the osteosarcoma cell line U2OS, while none affect the survival of the non-cancerous NOK cell line. One of these isoforms, lacking three exons and encoding the N-terminal end of the mda-7/IL-24 protein sequence, caused levels of apoptosis that were higher than those caused by the full-length mda-7/IL-24 variant. Additionally, we found that the ratio of isoform expression can be modified by the splice factor SRp55. This regulation suggests that alternative splicing of mda-7/IL-24 is under tight control in the cell, and can be modified under various cellular conditions, such as DNA damage. In addition to providing new insights into the function of an important tumor suppressor gene, these findings may also point toward new avenues for cancer treatment.     

Seasonal variation in whole blood cytokine production after LPS stimulation in normal individuals

We examined seasonal differences in whole blood cytokine production after endotoxin (LPS) stimulation in 17 healthy individuals from an urban area having normal sleep/wakefulness pattern. We used 500 pg/ml of LPS for incubation period of 4 h to stimulate 100 microl of whole blood of the same subjects in June, September, February, and March. We found no differences in the circulating total WBCs and differentials including monocytes between different seasons. We found during September (autumn) a reduced pro-inflammatory cytokine production in terms of TNF-alpha and IL-6 production compared to the other seasons. We also found a reduced anti-inflammatory cytokine production in June (summer) and September (autumn) in terms of IL-10, TNF-RI and TNF-RII compared to February (winter) and March (spring). Our results suggest that in early summer there is a predominating pro-inflammatory cytokine response which is counterbalanced early in autumn. These results may have significant implications in the determination of reference values, in exploration of immune response and inflammatory disease prevalence between different seasons, in determining LPS tolerance (immunoparalysis) and planning clinical trials and immunomodulary therapies. However, the effect of dark/light exposure differences on the circadian periodicity in the responsiveness of immune cells during different seasons should be further investigated.     

Employee Attitudes about the Impact of Visitation Dogs on a College Campus

Therapy and visitation dogs are becoming more common on college campuses to provide comfort and support to students, but little attention has been given to the concerns of faculty and staff who share space with the dogs in their workplaces. The purpose of this study was to assess the perceptions of faculty and staff with regard to both the benefits and the hazards (e.g., dander, bites, fleas) and risks associated with the presence of visitation dogs in their workplaces. One hundred and thirty-eight employees who worked in buildings with resident visitation dogs completed an online survey about their perceptions of the hazards and risks of the dogs and the effects of dogs on the wellbeing of both students and employees. In general, employees perceived that the dogs presented minimal risks, and most employees believed that they can reduce stress and provide comfort to students on campus. There were a few employees, however, who reported that the dogs did not improve the work environment and conferred no benefits to the staff or students. The findings of the present survey support the mostly positive attitudes that people have for dogs in the workplace, but they also highlight a potential challenge: accommodating individuals who believe very strongly that dogs do not belong in work environments.     

First report of the potentially toxic marine diatom Pseudo‐nitzschia simulans (Bacillariophyceae) from the East Australian Current

Certain species of the marine diatom genus Pseudo‐nitzschia are responsible for the production of the domoic acid (DA), a neurotoxin that can bioaccumulate in the food chain and cause amnesic shellfish poisoning (ASP) in animals and humans. This study extends our knowledge by reporting on the first observation of the potentially toxic species Pseudo‐nitzschia simulans from this region. One clonal strain of P. simulans was isolated from the East Australian Current and characterized using light and transmission electron microscopy, and phylogenetic analyses based on regions of the internal transcribed spacer (ITS) and the D1–D3 region of the large subunit (LSU) of the nuclear‐encoded ribosomal deoxyribonucleic acid (rDNA), as well as examined for DA production as measured by liquid chromatography–mass spectrometry. Although this strain was non‐toxic under the defined growth conditions, the results unambiguously confirmed that this isolate is the potentially toxic species P. simulans – the first report of this species from the Southern Hemisphere.     

Reducing Deaths from Severe Pneumonia in Children in Malawi by Improving Delivery of Pneumonia Case Management

Objective

To evaluate the pneumonia specific case fatality rate over time following the implementation of a Child Lung Health Programme (CLHP) within the existing government health services in Malawi to improve delivery of pneumonia case management.

Methods

A prospective, nationwide public health intervention was studied to evaluate the impact on pneumonia specific case fatality rate (CFR) in infants and young children (0 to 59 months of age) following the implementation of the CLHP. The implementation was step-wise from October 1^st 2000 until 31^st December 2005 within paediatric inpatient wards in 24 of 25 district hospitals in Malawi. Data analysis compared recorded outcomes in the first three months of the intervention (the control period) to the period after that, looking at trend over time and variation by calendar month, age group, severity of disease and region of the country. The analysis was repeated standardizing the follow-up period by using only the first 15 months after implementation at each district hospital.

Findings

Following implementation, 47,228 children were admitted to hospital for severe/very severe pneumonia with an overall CFR of 9•8%. In both analyses, the highest CFR was in the children 2 to 11 months, and those with very severe pneumonia. The majority (64%) of cases, 2–59 months, had severe pneumonia. In this group there was a significant effect of the intervention Odds Ratio (OR) 0•70 (95%CI: 0•50–0•98); p = 0•036), while in the same age group children treated for very severe pneumonia there was no interventional benefit (OR 0•97 (95%CI: 0•72–1•30); p = 0•8). No benefit was observed for neonates (OR 0•83 (95%CI: 0•56–1•22); p = 0•335).

Conclusions

The nationwide implementation of the CLHP significantly reduced CFR in Malawian infants and children (2–59 months) treated for severe pneumonia. Reasons for the lack of benefit for neonates, infants and children with very severe pneumonia requires further research.     

Serpin polymerization is prevented by a hydrogen bond network that is centered on his-334 and stabilized by glycerol

Polymerization of serpins commonly results from mutations in the shutter region underlying the bifurcation of strands 3 and 5 of the A-sheet, with entry beyond this point being barred by a H-bond network centered on His-334. Exposure of this histidine in antithrombin, which has a partially opened sheet, allows polymerization and peptide insertion to occur at pH 6 or less when His-334 will be predictably protonated with disruption of the H-bond network. Similarly, thermal stability of antithrombin is pH-dependent with a single unfolding transition at pH 6, but there is no such transition when His-334 is buried by a fully closed A-sheet in heparin-complexed antithrombin or in alpha(1)-antitrypsin. Replacement of His-334 in alpha(1)-antitrypsin by a serine or alanine at pH 7.4 results in the same polymerization and loop-peptide acceptance observed with antithrombin at low pH. The critical role of His-334 and the re-formation of its H-bond network by the conserved P8 threonine, on the full insertion of strand 4, are relevant for the design of therapeutic blocking agents. This is highlighted here by the crystallographic demonstration that glycerol, which at high concentrations blocks polymerization, can replace the P8 threonine and re-form the disrupted H-bond network with His-334.