Faint young Sun paradox remains

The Sun was fainter when the Earth was young, but the climate was generally at least as warm as today; this is known as the `faint young Sun paradox'. Rosing et al. [1] claim that the paradox can be resolved by making the early Earth's clouds and surface less reflective. We show that, even with the strongest plausible assumptions, reducing cloud and surface albedos falls short by a factor of two of resolving the paradox. A temperate Archean climate cannot be reconciled with the low level of CO2 suggested by Rosing et al. [1]; a stronger greenhouse effect is needed.Comment: 3 pages, no figures. In press in Nature. v2 corrects typo in author list in original submissio

Denitrification and nitrous oxide emissions from riparian forests soils exposed to prolonged nitrogen runoff

Compared to upland forests, riparian forest soils have greater potential to remove nitrate (NO3) from agricultural run-off through denitrification. It is unclear, however, whether prolonged exposure of riparian soils to nitrogen (N) loading will affect the rate of denitrification and its end products. This research assesses the rate of denitrification and nitrous oxide (N2O) emissions from riparian forest soils exposed to prolonged nutrient run-off from plant nurseries and compares these to similar forest soils not exposed to nutrient run-off. Nursery run-off also contains high levels of phosphate (PO4). Since there are conflicting reports on the impact of PO4 on the activity of denitrifying microbes, the impact of PO4 on such activity was also investigated. Bulk and intact soil cores were collected from N-exposed and non-exposed forests to determine denitrification and N2O emission rates, whereas denitrification potential was determined using soil slurries. Compared to the non-amended treatment, denitrification rate increased 2.7- and 3.4-fold when soil cores collected from both N-exposed and non-exposed sites were amended with 30 and 60 μg NO3-N g-1 soil, respectively. Net N2O emissions were 1.5 and 1.7 times higher from the N-exposed sites compared to the non-exposed sites at 30 and 60 μg NO3-N g-1 soil amendment rates, respectively. Similarly, denitrification potential increased 17 times in response to addition of 15 μg NO3-N g-1 in soil slurries. The addition of PO4 (5 μg PO4–P g-1) to soil slurries and intact cores did not affect denitrification rates. These observations suggest that prolonged N loading did not affect the denitrification potential of the riparian forest soils; however, it did result in higher N2O emissions compared to emission rates from non-exposed forests

Global health partnerships for continuing medical education: Lessons from successful partnerships

The past decade has witnessed an increase in global partnerships created to strengthen health systems and provide training to health professionals in low- and middle-income countries. These partnerships are complex interventions. This study focused on unpacking the characteristics of global partnerships that provide continuing education for health professionals. A realist approach underpinned the research design to identify the mechanisms that shape successful global partnerships. Two case studies focusing on global continuing medical education (CME) were studied longitudinally using a realist evaluation approach. To complement that finding, published research reports of global CME partnerships were synthesized using a realist synthesis approach. Data were collected over a three-year period and included interviews, participant observations, document reviews, and surveys. A hybrid thematic approach guided the data analysis. The study results suggested that global CME partnerships are highly dependent on human factors. On the one hand, motivational factors related to individual players help to shape the partnership goals, directions, and outcomes. On the other hand, relational factors such as trust, communication, and understanding play a key role in developing and sustaining global partnerships. As such, these partnerships highly rely on the individuals who champion the partnership at the country level or at the partnership level and in their ability to build relationships as well as empower key stakeholders

The association between clinical integration of care and transfer of veterans with acute coronary syndromes from primary care VHA hospitals

BACKGROUND: Few studies report on the effect of organizational factors facilitating transfer between primary and tertiary care hospitals either within an integrated health care system or outside it. In this paper, we report on the relationship between degree of clinical integration of cardiology services and transfer rates of acute coronary syndrome (ACS) patients from primary to tertiary hospitals within and outside the Veterans Health Administration (VHA) system. METHODS: Prospective cohort study. Transfer rates were obtained for all patients with ACS diagnoses admitted to 12 primary VHA hospitals between 1998 and 1999. Binary variables measuring clinical integration were constructed for each primary VHA hospital reflecting: presence of on-site VHA cardiologist; referral coordinator at the associated tertiary VHA hospital; and/or referral coordinator at the primary VHA hospital. We assessed the association between the integration variables and overall transfer from primary to tertiary hospitals, using random effects logistic regression, controlling for clustering at two levels and adjusting for patient characteristics. RESULTS: Three of twelve hospitals had a VHA cardiologist on site, six had a referral coordinator at the tertiary VHA hospital, and four had a referral coordinator at the primary hospital. Presence of a VHA staff cardiologist on site and a referral coordinator at the tertiary VHA hospital decreased the likelihood of any transfer (OR 0.45, 95% CI 0.27–0.77, and 0.46, p = 0.002, CI 0.27–0.78). Conversely, having a referral coordinator at the primary VHA hospital increased the likelihood of transfer (OR 6.28, CI 2.92–13.48). CONCLUSIONS: Elements of clinical integration are associated with transfer, an important process in the care of ACS patients. In promoting optimal patient care, clinical integration factors should be considered in addition to patient characteristics

Arabidopsis MKS1 Is Involved in Basal Immunity and Requires an Intact N-terminal Domain for Proper Function

Innate immune signaling pathways in animals and plants are regulated by mitogen-activated protein kinase (MAPK) cascades. MAP kinase 4 (MPK4) functions downstream of innate immune receptors via a nuclear substrate MKS1 to regulate the activity of the WRKY33 transcription factor, which in turn controls the production of anti-microbial phytoalexins.We investigate the role of MKS1 in basal resistance and the importance of its N- and C-terminal domains for MKS1 function. We used the information that mks1 loss-of-function partially suppresses the mpk4 loss-of-function phenotype, and that transgenic expression of functional MKS1 in mpk4/mks1 double mutants reverted the mpk4 dwarf phenotype. Transformation of mks1/mpk4 with mutant versions of MKS1 constructs showed that a single amino acid substitution in a putative MAP kinase docking domain, MKS1-L32A, or a truncated MKS1 version unable to interact with WRKY33, were deficient in reverting the double mutant to the mpk4 phenotype. These results demonstrate functional requirement in MKS1 for the interaction with MPK4 and WRKY33. In addition, nuclear localization of MKS1 was shown to depend on an intact N-terminal domain. Furthermore, loss-of-function mks1 mutants exhibited increased susceptibility to strains of Pseudomonas syringae and Hyaloperonospora arabidopsidis, indicating that MKS1 plays a role in basal defense responses.Taken together, our results indicate that MKS1 function and subcellular location requires an intact N-terminus important for both MPK4 and WRKY33 interactions

Non-host resistance to penetration and hyphal growth of Magnaporthe oryzae in Arabidopsis

Rice blast caused by Magnaporthe oryzae is a devastating disease of rice. Mechanisms of rice resistance to blast have been studied extensively, and the rice–M. oryzae pathosystem has become a model for plant–microbe interaction studies. However, the mechanisms of non-host resistance (NHR) to rice blast in other plants remain poorly understood. We found that penetration resistance to M. oryzae in multiple mutants, including pen2 NahG pmr5 agb1 and pen2 NahG pmr5 mlo2 plants, was severely compromised and that fungal growth was permitted in penetrated epidermal cells. Furthermore, rice Pi21 enhanced movement of infection hyphae from penetrated Arabidopsis epidermal cells to adjacent mesophyll cells. These results indicate that PEN2, PMR5, AGB1, and MLO2 function in both penetration and post-penetration resistance to M. oryzae in Arabidopsis, and suggest that the absence of rice Pi21 contributed to Arabidopsis NHR to M. oryzae

Interleukin 21 inhibits cancer-mediated FOXP3 induction in naïve human CD4 T cells

IL-21 is known to promote anti-tumour immunity due to its ability to promote T cell responses and counteract Treg-mediated suppression. It has also been shown to limit Treg frequencies during tumour-antigen stimulations. However, whether this represents inhibition of FOXP3 induction in naïve CD4 T cells or curtailed expansion of natural Treg remains unclear. Moreover, whether this effect is maintained in an environment of tumour-derived immunosuppressive factors is not known. Here, we show that in the context of a number of cancers, naïve CD45RA+ CD4 T cells are induced to express high levels of FOXP3, and that FOXP3 expression correlates with inhibition of T cell proliferation. FOXP3 expression was most potently induced by tumours secreting higher levels of total and active TGFβ1 and this induction could be potently counteracted with IL-21, restoring T cell proliferation. We conclude that Treg induction in naïve T cells is a common phenomenon amongst a number of different cancers and that the ability of IL-21 to counteract this effect is further evidence of its promise in cancer therapy

The First Sequenced Carnivore Genome Shows Complex Host-Endogenous Retrovirus Relationships

Host-retrovirus interactions influence the genomic landscape and have contributed substantially to mammalian genome evolution. To gain further insights, we analyzed a female boxer (Canis familiaris) genome for complexity and integration pattern of canine endogenous retroviruses (CfERV). Intriguingly, the first such in-depth analysis of a carnivore species identified 407 CfERV proviruses that represent only 0.15% of the dog genome. In comparison, the same detection criteria identified about six times more HERV proviruses in the human genome that has been estimated to contain a total of 8% retroviral DNA including solitary LTRs. These observed differences in man and dog are likely due to different mechanisms to purge, restrict and protect their genomes against retroviruses. A novel group of gammaretrovirus-like CfERV with high similarity to HERV-Fc1 was found to have potential for active retrotransposition and possibly lateral transmissions between dog and human as a result of close interactions during at least 10.000 years. The CfERV integration landscape showed a non-uniform intra- and inter-chromosomal distribution. Like in other species, different densities of ERVs were observed. Some chromosomal regions were essentially devoid of CfERVs whereas other regions had large numbers of integrations in agreement with distinct selective pressures at different loci. Most CfERVs were integrated in antisense orientation within 100 kb from annotated protein-coding genes. This integration pattern provides evidence for selection against CfERVs in sense orientation relative to chromosomal genes. In conclusion, this ERV analysis of the first carnivorous species supports the notion that different mammals interact distinctively with endogenous retroviruses and suggests that retroviral lateral transmissions between dog and human may have occurred