Ethnicity and conflict: theory and facts

Over the second half of the 20th century, conflicts within national boundaries became increasingly dominant. One-third of all countries experienced civil conflict. Many (if not most) such conflicts involved violence along ethnic lines. On the basis of recent theoretical and empirical research, we provide evidence that preexisting ethnic divisions do influence social conflict. Our analysis also points to particular channels of influence. Specifically, we show that two different measures of ethnic division--polarization and fractionalization--jointly influence conflict, the former more so when the winners enjoy a "public" prize (such as political power or religious hegemony), the latter more so when the prize is "private" (such as looted resources, government subsidies, or infrastructures). The available data appear to strongly support existing theories of intergroup conflict. Our argument also provides indirect evidence that ethnic conflicts are likely to be instrumental, rather than driven by primordial hatreds.     

Unraveling the life history of successful invaders

Despite considerable current interest in biological invasions, the common life-history characteristics of successful invaders remain elusive. The widely held hypothesis that successful invaders have high reproductive rates has received little empirical support; however, alternative possibilities are seldom considered. Combining a global comparative analysis of avian introductions (>2700 events) with demographic models and phylogenetic comparative methods, we show that although rapid population growth may be advantageous during invasions under certain circumstances, more generally successful invaders are characterized by life-history strategies in which they give priority to future rather than current reproduction. High future breeding expectations reduce the costs of reproductive failure under uncertain conditions and increase opportunities to explore the environment and respond to novel ecological pressures.     

Regulated virulence controls the ability of a pathogen to compete with the gut microbiota

The virulence mechanisms that allow pathogens to colonize the intestine remain unclear. Here, we show that germ-free animals are unable to eradicate Citrobacter rodentium, a model for human infections with attaching and effacing bacteria. Early in infection, virulence genes were expressed and required for pathogen growth in conventionally raised mice but not germ-free mice. Virulence gene expression was down-regulated during the late phase of infection, which led to relocation of the pathogen to the intestinal lumen where it was outcompeted by commensals. The ability of commensals to outcompete C. rodentium was determined, at least in part, by the capacity of the pathogen and commensals to grow on structurally similar carbohydrates. Thus, pathogen colonization is controlled by bacterial virulence and through competition with metabolically related commensals.     

Evaluating a group-based intervention to improve the safety of meat in Bodija Market,Ibadan, Nigeria

We evaluated a group-based, participatory training intervention to improve food safety among meat processors and retailers in Bodija Market, Ibadan, Nigeria. An interactive training workshop was held for Butchers Associations’ representatives who were selected to pass on information and training to their group. Meat hygiene knowledge, attitude and practice was assessed before attending the workshop and afterwards (n = 63). It was also assessed for those who did not attend the workshop (n = 68) but were intended recipients of training through their association. Microbiological quality of meat was assessed before and after the workshop (n = 400 samples). After the workshop, participants significantly improved knowledge, attitude and practice in key food safety aspects; specifically, understanding sources of contamination and food-borne diseases, use of bleach and disinfectant and hand washing. Participants also shared information with an average of 18 other group members and improvements were seen in group members who did not attend the workshop but received training through their Butchers Association. Microbiological quality of meat sold also significantly improved after the intervention. In conclusion, participatory, group-based methods targeted at meat processors and retailers can improve meat hygiene knowledge, attitude and practice as well as the microbiological quality and hence safety of meat.

     

Leptospirosis as the most frequent infectious disease impairing productivity in small ruminants in Rio de Janeiro,Brazil

Despite the importance of small ruminants breeding in developing countries, milk/meat productivity remains unsatisfactory. Infectious diseases, such as leptospirosis, brucellosis, and small ruminant lentiviruses (SRLVs), contribute to this scenario. The objective of the present study was to determine the role of each of these diseases in the productivity of small ruminants breeding in Rio de Janeiro, Brazil. In goats, 343 samples were tested for leptospirosis, 560 for Brucella abortus, and 506 for caprine arthritis-encephalitis (CAE), whereas in sheep, 308 samples were tested for leptospirosis, 319 for B. abortus, 374 for Brucella ovis, and 278 for Maedi-Visna (MV). Regarding leptospirosis, 25.9% of goats and 47.4% sheep were seroreactive, with serovar Hardjo the most prevalent in both species. Anti-B. abortus agglutinins were found in 0.7% of all samples, exclusively in goats. In relation to SRLVs, 8.6% of goats and 3.2% of sheep samples were positive for CAE and MV, respectively. Leptospirosis was the major infectious problem in the small ruminants sampled and may contribute to impaired productivity of these animals.     

Effects of intra-mammary bacterial infection with coagulase negative staphylococci and stage of lactation on shedding of epithelial cells and infiltration of leukocytes into milk: comparison among cows, goats and sheep

The effects of mammary gland bacterial infection and stage of lactation on leukocyte infiltration into the mammary gland were compared among cows, goats and sheep. Animals were at two stages of lactation: mid or late. In mid-lactation animals, bacterial-free glands and coagulase negative Staphylococcus (CNS)-infected glands were compared. In late lactation only uninfected glands were studied. Of mid-lactation bacteria-free animals, goats had the highest number of leukocytes and % polymorphonuclears (PMNs), whereas sheep had the lowest and leukocytes number in cows were intermediate between sheep and goats. Based on %PMN, two cell clusters were found in sheep, which overlapped with the parallel cell clusters of cows and goats, but with a slightly higher number of leukocytes in each cell cluster. At late lactation, goats had higher values for %PMN and leukocyte numbers in comparison to cows, which had a similar cellular profile to sheep. The cellular immune response to CNS infection was similar for the three animal species, although the number of cells was different, while the basal cell level at mid-lactation and especially at the end of lactation was species specific.     

Epidemiological description of the sea lice (Caligus rogercresseyi) situation in southern Chile in August 2007

Salmon sea lice represent one of the most important threats to salmon farming throughout the world. Results of private monitoring efforts have shown an increase in the number of positive cages and cage-level abundance of sea lice in southern Chile since 2004. As a consequence, the Chilean Fisheries Service implemented an Official Surveillance Program in the main salmon production area of southern Chile to assess the situation of sea lice in fish farms. Results showed that the prevalence of sea lice in the fish farms was 53.4%, ranging from 3.5% in Puerto Aysén to 100% in the Seno de Reloncaví zone. The average sea lice abundance was 11.8 per fish (Geometrical mean (GM)=8.61, 95% CI (2.1-6.9)). The highest levels were found in Seno de Reloncaví (GM=24.99, 95% CI (15.9-39.2)), Hornopirén (GM=14.7, 95% CI (10.4-20.8)) and Chiloé norte (GM=9.75, 95% CI (1-1.9)), and the lowest loads were observed in Puerto Aysén (GM=1.35, 95%CI (1-1.9)) and Puerto Cisnes (GM=1.67, 95%CI (1.1-2.6)). Salmo salar and Oncorhynchus mykiss had the highest abundance levels (GM=6.93, 95% CI (5.7-8.5), and (GM=5.55, 95% CI (3.6-8.5), respectively). O. kisutch showed lower levels (GM=1.34, 95% CI (1-1.7)), apparently being more resistant to infestation. Sea lice in farmed salmon are widely distributed in different zones of southern Chile, and are becoming a serious threat to this industry. Prevalence and abundance levels were found to be generally high, decreasing in southern zones.     

Perspectives in dryland restoration: approaches for climate change adaptation

Reforestation efforts in dryland ecosystems frequently encounter drought and limited soil productivity, although both factors usually interact synergistically to worsen water stress for outplanted seedlings. Land degradation in drylands (e.g. desertification) usually reduces soil productivity and, especially, soil water availability. In dry sub-humid regions, forest fires constitute a major disturbance affecting ecosystem dynamics and reforestation planning. Climate change projections indicate an increase of drought and more severe fire regime in many dryland regions of the world. In this context, the main target of plantation technology development is to overcome transplant shock and likely adverse periods, and in drylands this is mostly related to water limitations. In this paper, we discuss some selected steps that we consider critical for improving success in outplanting woody plants, both under current and projected climate change conditions including: (1) Plant species selection, (2) Improved nursery techniques, and (3) Improved planting techniques. The number of plant species used in reforestation is increasing rapidly, moving from a reduced set of well-known, easy-to-grow, widely used species, to a large variety of promising native species. Available technologies allow for reintroducing native plants and recovering critical ecosystem functions for many degraded drylands. However, climate change projections introduce large uncertainties about the sustainability of current reforestation practices. To cope with these uncertainties, adaptive restoration approaches are suggested, on the basis of improved plant quality, improved techniques for optimizing rain use efficiency in plantations, and exploring native plant species, including provenances and genotypes, for their resilience to fire and water use efficiency.     

Development of Purkinje cells in the ovine brain

Purkinje cells are involved in many vital functions within the body. Twenty ovine fetuses ranging from 2 to 5 months of gestation, two lambs in the first week after birth and three adult sheep were studied. Sections of the cerebellum were stained with haematoxylin and eosin, cresyl violet and Klüver-Barrera. This study indicates that Purkinje cells began to appear after the 15(th) week of gestation. There were varying degrees of development of Purkinje cells in different zones of the cerebellum. Our findings in sheep fetuses suggest that the maturation of Purkinje cells starts in the caudal regions of the cerebellum and that the process begins in the vermis before it does in the cerebellar hemispheres. The alignment of Purkinje cells was found to be very regular in the caudal regions of the cerebellum. A partial absence of Purkinje cells in the rostral regions of the cerebellum was observed in both sheep fetuses and adult sheep. In the first post-natal week, some ectopic Purkinje cells were found in the white matter of the cerebellum.