Distinct colonization patterns and cDNA-AFLP transcriptome profiles in compatible and incompatible interactions between melon and different races of Fusarium oxysporum f. sp. melonis

Background: Fusarium oxysporum f. sp. melonis Snyd. & Hans. (FOM) causes Fusarium wilt, the most important infectious disease of melon (Cucumis melo L.). The four known races of this pathogen can be distinguished only by infection on appropriate cultivars. No molecular tools are available that can discriminate among the races, and the molecular basis of compatibility and disease progression are poorly understood. Resistance to races 1 and 2 is controlled by a single dominant gene, whereas only partial polygenic resistance to race 1,2 has been described. We carried out a large-scale cDNA-AFLP analysis to identify host genes potentially related to resistance and susceptibility as well as fungal genes associated with the infection process. At the same time, a systematic reisolation procedure on infected stems allowed us to monitor fungal colonization in compatible and incompatible host-pathogen combinations. Results: Melon plants (cv. Charentais Fom-2), which are susceptible to race 1,2 and resistant to race 1, were artificially infected with a race 1 strain of FOM or one of two race 1,2 w strains. Host colonization of stems was assessed at 1, 2, 4, 8, 14, 16, 18 and 21 days post inoculation (dpi), and the fungus was reisolated from infected plants. Markedly different colonization patterns were observed in compatible and incompatible host-pathogen combinations. Five time points from the symptomless early stage (2 dpi) to obvious wilting symptoms (21 dpi) were considered for cDNA-AFLP analysis. After successful sequencing of 627 transcript-derived fragments (TDFs) differentially expressed in infected plants, homology searching retrieved 305 melon transcripts, 195 FOM transcripts expressed in planta and 127 orphan TDFs. RNA samples from FOM colonies of the three strains grown in vitro were also included in the analysis to facilitate the detection of in planta-specific transcripts and to identify TDFs differentially expressed among races/strains. Conclusion: Our data suggest that resistance against FOM in melon involves only limited transcriptional changes, and that wilting symptoms could derive, at least partially, from an active plant response. We discuss the pathogen-derived transcripts expressed in planta during the infection process and potentially related to virulence functions, as well as transcripts that are differentially expressed between the two FOM races grown in vitro. These transcripts provide candidate sequences that can be further tested for their ability to distinguish between races. Sequence data from this article have been deposited in GenBank, Accession Numbers: HO867279-HO867981

Breaking Functional Connectivity into Components: A Novel Approach Using an Individual-Based Model, and First Outcomes

Landscape connectivity is a key factor determining the viability of populations in fragmented landscapes. Predicting ‘functional connectivity’, namely whether a patch or a landscape functions as connected from the perspective of a focal species, poses various challenges. First, empirical data on the movement behaviour of species is often scarce. Second, animal-landscape interactions are bound to yield complex patterns. Lastly, functional connectivity involves various components that are rarely assessed separately. We introduce the spatially explicit, individual-based model FunCon as means to distinguish between components of functional connectivity and to assess how each of them affects the sensitivity of species and communities to landscape structures. We then present the results of exploratory simulations over six landscapes of different fragmentation levels and across a range of hypothetical bird species that differ in their response to habitat edges. i) Our results demonstrate that estimations of functional connectivity depend not only on the response of species to edges (avoidance versus penetration into the matrix), the movement mode investigated (home range movements versus dispersal), and the way in which the matrix is being crossed (random walk versus gap crossing), but also on the choice of connectivity measure (in this case, the model output examined). ii) We further show a strong effect of the mortality scenario applied, indicating that movement decisions that do not fully match the mortality risks are likely to reduce connectivity and enhance sensitivity to fragmentation. iii) Despite these complexities, some consistent patterns emerged. For instance, the ranking order of landscapes in terms of functional connectivity was mostly consistent across the entire range of hypothetical species, indicating that simple landscape indices can potentially serve as valuable surrogates for functional connectivity. Yet such simplifications must be carefully evaluated in terms of the components of functional connectivity they actually predict

Towards Understanding Workplace Learning Through Theorising Practice: At Work in Hospital Emergency Departments

© 2012, Springer Science+Business Media Dordrecht. Focusing on the experiences of one 95-year-old patient, Jane Edna, this chapter uses a practice theory approach to investigate in situ ‘knowing-in-practice’ (Gherardi, Situated knowledge and situated action: what do practice-based studies promise? In Barry D, Hansen H (eds) The Sage handbook of new approaches in management and organization. Sage, Los Angeles, pp 516–525, 370, 2009b) in emergency health care. In particular, we discuss relationships between work, knowledge/knowing and learning through an examination of professional and interprofessional ‘doings and sayings’ (Schatzki, Organ Stud 27(12):1863–1873, 2006) by clinicians around the bedside of Jane Edna, who spends over 11 h in a busy Australian hospital emergency department (ED). We present and explore some of the ethnographic and spoken interactional data recorded between Jane Edna and her team of clinicians. We are primarily concerned with the practices and the potential for learning practices that the ED affords the junior doctor who directs Jane Edna’s care. The junior doctor’s ‘doings’, ‘sayings’ and ‘beings’ concentrate on applying biomedical scientific knowledge – practising medicine learned in vacuo – privileged within the institutional order (Sarangi and Roberts (eds), Talk, work and institutional order: discourse in medical, mediation and management settings. Mouton de Gruyter, Berlin/New York, 1999) of the ED. We consider the interplay and consequences of differentially valued epistemologies (Cook and Brown, Organ Sci 10(4):381–400, 1999), in particular, the dominance of ‘organisational knowledge’ (knowledge possessed by individuals – here, high-status doctors). We discuss how ‘organisational knowing’ (the collective working/knowing of all the participants who care for Jane Edna including Jane Edna herself) and ‘knowing-in-practice’ (Gherardi, Learn Organ 16(5):352–359, 2009a) could be more explicitly foregrounded to help create the team-based models of care that are enshrined in twenty-first-century hospital policies. The chapter concludes with some implications for understanding practice and learning practice in organisations as doing knowledge together where knowledge is emergent and co-constructed in situ through language, actions, relationships and material arrangements

Observationally derived rise in methane surface forcing mediated by water vapour trends

Atmospheric methane (CH4) mixing ratios exhibited a plateau between 1995 and 2006 and have subsequently been increasing. While there are a number of competing explanations for the temporal evolution of this greenhouse gas, these prominent features in the temporal trajectory of atmospheric CH4 are expected to perturb the surface energy balance through radiative forcing, largely due to the infrared radiative absorption features of CH4. However, to date this has been determined strictly through radiative transfer calculations. Here, we present a quantified observation of the time series of clear-sky radiative forcing by CH4 at the surface from 2002 to 2012 at a single site derived from spectroscopic measurements along with line-by-line calculations using ancillary data. There was no significant trend in CH4 forcing between 2002 and 2006, but since then, the trend in forcing was 0.026 ± 0.006 (99.7% CI) W m2 yr-1. The seasonal-cycle amplitude and secular trends in observed forcing are influenced by a corresponding seasonal cycle and trend in atmospheric CH4. However, we find that we must account for the overlapping absorption effects of atmospheric water vapour (H2O) and CH4 to explain the observations fully. Thus, the determination of CH4 radiative forcing requires accurate observations of both the spatiotemporal distribution of CH4 and the vertically resolved trends in H2O

Ecosystems, food, agriculture, and ethics

Includes bibliographical references.Humans live in towns and are civilized, but by nature too are residents on landscapes, rural. An ecology lies in the background of culture, providing ecosystem services. Some dimensions of health pervade both wild and agricultural nature. Humans in recent times have dramatically transformed and degraded landscapes, a huge ecological footprint. Humans now are entering an Anthropocene Epoch, escalating industrial agriculture, in both developed and developing nations, hoping for and threatening global sustainable development. A wiser goal might be a sustainable biosphere, the ultimate unit of survival