The effects of scales, flows and filters on property rights and collective action in watershed management:

Research and policy on property rights, collective action and watershed management requires good understanding of ecological and socio-political processes at different social-spatial scales. On-farm soil erosion is a plot or farm-level problem that can be mitigated through more secure property rights for individual farmers, while the sedimentation of streams and deterioration of water quality are larger-scale problems that may require more effective collective action and / or more secure property rights at the village or catchment scale. Differences in social-political contexts across nations and regions also shape property rights and collective action institutions. For example, circumstances in the Lake Victoria basin in East Africa require particular attention to collective action and property rights problems in specific “hot spot” areas where insecure tenure leads to overuse or under-investment. Circumstances in the uplands of Southeast Asia require analysis of the opportunities for negotiating more secure rights for farmers in exchange for stronger collective action by farmer groups for maintaining essential watershed functions.

Field trip to West Kalimantan. Mission report. Identification of smallholder rubber agroforestry systems : sustainable alternatives

L'objectif principal de ce document, outre le rapport des activités, est de présenter la méthodologie du SRAP et les priorités identifiées par l'équipe (après analyse in situ de la situation locale) en terme de recherche, expérimentation à la plantation, enquêtes à réaliser. Visite du projet PKR-GK (West-Kalimatan smallholder rubber development project) du GAPKINDO. Identification des partenaires pour la réalisation de la phase 1 (1994-1995) du projet SRAP. Quatre types d'essais en champs ont été identifiés et sont décrits en annex

The Imperata grasslands of tropical Asia: area, distribution, and typology

The rehabilitation or intensified use of Imperata grasslands will require a much better understanding of their area, distribution, and characteristics. We generated estimates of the area of Imperata grasslands in tropical Asia, and suggested a typology of Imperata grasslands that may be useful to define the pathways toward appropriate land use intensification. We conclude that the area of Imperata grasslands in Asia is about 35 million ha. This about 4% of the total land area. The countries with the largest area of Imperata grasslands are Indonesia (8.5 million ha) and India (8.0 million ha). Those with the largest proportion of their surface area covered with Imperata are Sri Lanka (23%), the Philippines (17%), and Vietnam (9%). Laos, Thailand, Myanmar, and Bangladesh evidently all have similar proportions of their land area infested with Imperata (about 3 to 4%). Malaysia (< 1%), Cambodia (1%), and the southern part of China (2%) have but a minor proportion of their total land area in Imperata. The species was found widely distributed on the full range of soil orders. It occupied both fertile (e.g. some of the Inceptisols and Andisols) and infertile soils (Ultisols and Oxisols) across a wide range of climates and elevations. Imperata lands fall into four mapping scale-related categories: Mega-grasslands, itmacro-grasslands, meso-grasslands, and micro-grasslands. The mega-grasslands are often referred to as ‘sheet Imperata’. They are the large contiguous areas of Imperata that would appear on small-scale maps of say 1:1,000,000. We propose that this basic typology be supplemented with a number of additional components that have a key influence on intensification pathways: land quality, market access, and the source of power for tillage. The typology was applied in a case study of Indonesian villages in the vicinity of Imperata grasslands. We propose an international initiative to map and derive a more complete and uniform picture of the area of the Imperata grasslands. This should include selected studies to understand conditions at the local level. These are critical to build the appreciation of change agents for the indigenous systems of resource exploitation, and how they relate to local needs, values and constraints

Structural Basis of Cytotoxicity Mediated by the Type III Secretion Toxin ExoU from Pseudomonas aeruginosa

The type III secretion system (T3SS) is a complex macromolecular machinery employed by a number of Gram-negative pathogens to inject effectors directly into the cytoplasm of eukaryotic cells. ExoU from the opportunistic pathogen Pseudomonas aeruginosa is one of the most aggressive toxins injected by a T3SS, leading to rapid cell necrosis. Here we report the crystal structure of ExoU in complex with its chaperone, SpcU. ExoU folds into membrane-binding, bridging, and phospholipase domains. SpcU maintains the N-terminus of ExoU in an unfolded state, required for secretion. The phospholipase domain carries an embedded catalytic site whose position within ExoU does not permit direct interaction with the bilayer, which suggests that ExoU must undergo a conformational rearrangement in order to access lipids within the target membrane. The bridging domain connects catalytic domain and membrane-binding domains, the latter of which displays specificity to PI(4,5)P2. Both transfection experiments and infection of eukaryotic cells with ExoU-secreting bacteria show that ExoU ubiquitination results in its co-localization with endosomal markers. This could reflect an attempt of the infected cell to target ExoU for degradation in order to protect itself from its aggressive cytotoxic action

Fitness of Isogenic Colony Morphology Variants of Pseudomonas aeruginosa in Murine Airway Infection

Chronic lung infections with Pseudomonas aeruginosa are associated with the diversification of the persisting clone into niche specialists and morphotypes, a phenomenon called ‘dissociative behaviour’. To explore the potential of P. aeruginosa to change its morphotype by single step loss-of–function mutagenesis, a signature-tagged mini-Tn5 plasposon library of the cystic fibrosis airway isolate TBCF10839 was screened for colony morphology variants under nine different conditions in vitro. Transposon insertion into 1% of the genome changed colony morphology into eight discernable morphotypes. Half of the 55 targets encode features of primary or secondary metabolism whereby quinolone production was frequently affected. In the other half the transposon had inserted into genes of the functional categories transport, regulation or motility/chemotaxis. To mimic dissociative behaviour of isogenic strains in lungs, pools of 25 colony morphology variants were tested for competitive fitness in an acute murine airway infection model. Six of the 55 mutants either grew better or worse in vivo than in vitro, respectively. Metabolic proficiency of the colony morphology variant was a key determinant for survival in murine airways. The most common morphotype of self-destructive autolysis did unexpectedly not impair fitness. Transposon insertions into homologous genes of strain PAO1 did not reproduce the TBCF10839 mutant morphotypes for 16 of 19 examined loci pointing to an important role of the genetic background on colony morphology. Depending on the chosen P. aeruginosa strain, functional genome scans will explore other areas of the evolutionary landscape. Based on our discordant findings of mutant phenotypes in P. aeruginosa strains PAO1, PA14 and TBCF10839, we conclude that the current focus on few reference strains may miss modes of niche adaptation and dissociative behaviour that are relevant for the microevolution of complex traits in the wild

The Effects of Scales, Flows and Filters on Property Rights and Collective Action in Watershed Management

Research and policy on property rights, collective action and watershed management requires good understanding of ecological and socio-political processes at different social-spatial scales. On-farm soil erosion is a plot or farm-level problem that can be mitigated through more secure property rights for individual farmers, while the sedimentation of streams and deterioration of water quality are larger-scale problems that may require more effective collective action and / or more secure property rights at the village or catchment scale. Differences in social-political contexts across nations and regions also shape property rights and collective action institutions. For example, circumstances in the Lake Victoria basin in East Africa require particular attention to collective action and property rights problems in specific “hot spot” areas where insecure tenure leads to overuse or under-investment. Circumstances in the uplands of Southeast Asia require analysis of the opportunities for negotiating more secure rights for farmers in exchange for stronger collective action by farmer groups for maintaining essential watershed functions