The beginnings of life: being some account of the nature, modes of origin and transformation of lower organisms. By H. Charlton Bastian.

1

Reproductive modes and fecundity of an assemblage of anuran amphibians in the Atlantic rainforest, Brazil

Reproductive modes and size-fecundity relationships are described for anurans from Picinguaba, a region of Atlantic rainforest on the northern coast of the state of São Paulo, Brazil. We observed 13 reproductive modes, confirming a high diversity of modes in the Atlantic rainforest. This diversity of reproductive modes reflects the successful use of diversified and humid microhabitats by anurans in this biome. We measured the snout-vent length of 715 specimens of 40 species of anurans. The size-fecundity relationship of 12 species was analyzed. Female snout-vent lengths explained between 57% and 81% of clutch size variation. Anurans with aquatic modes laid more eggs than those with terrestrial or arboreal modes. Larger eggs were deposited by species with specialized reproductive modes.

Transition modes and institutional outcomes in El Salvador and Guatemala

Institutions affect key dimensions of the political process –policy, stability, and conflict. The choice of institutions is thus consequential. I argue that transition modes affect the choice of institutions in predictable and systematic ways. The more balanced power is between the two main bargaining forces –regime elite and opposition– the likelier that the resulting institutions will be pluralistic. Contrarily, the more unbalanced power is in favour of regime elites vis a vis the opposition, the likelier that institutions will be majoritarian. The argument is tested for El Salvador and Guatemala.

Strategic mass killings

Since World War II there have been about fifty episodes of large-scale mass killings of civilians and massive forced displacements. They were usually meticulously planned and independent of military goals. We provide a model where conflict onset, conflict intensity and the decision to commit mass killings are all endogenous, with two main goals: (1) to identify the key variables and situations that make mass killings more likely to occur; and (2) to distinguish conditions under which mass killings and military conflict intensity reinforce each other from situations where they are substitute modes of strategic violence. We predict that mass killings are most likely in societies with large natural resources, significant proportionality constraints for rent sharing, low productivity and low state capacity. Further, massacres are more likely in a civil than in an interstate war, as in the latter group sizes matter less for future rents. In non polarized societies there are asymmetric equilibria with only the larger group wanting to engage in massacres. In such settings the smaller group compensates for this by fighting harder in the first place. In this case we can talk of mass killings and fighting efforts to be substitutes. In contrast, in polarized societies either both or none of the groups can be ready to do mass killings in case of victory. Under the "shadow of mass killings" groups fight harder. Hence, in this case massacres and fighting are complements. We also present novel empirical results on the role of natural resources in mass killings and on what kinds of ethnic groups are most likely to be victimized in massacres and forced resettlements, using group level panel data.

Probiotic microorganisms: 100 years of innovation and efficacy. Modes of action

AbstractArticle StructureFigures and TablesReferences Benefits from probiotic micro-organisms have been recognised for over 100 years, and as being useful in poultry for 50 years. Fuller (1989) redefined probiotics as ‘a live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance’. Benefits derived from this improved intestinal microbial balance could be reflected in performance or prevention of pathogen colonisation. Probiotic micro-organisms use in poultry production has been widely accepted and new opportunities arose from the 2006 EU ban on antimicrobial growth promoters. The majority of microbial products for compound feeds are made up from a relatively small number of micro-organisms that are normally present in the GI tract. They include non-sporulated bacteria, sporulated bacteria, fungi or yeasts; and presented from single to multi-strain products. A review on the proposed modes of action is presented including recent approaches to quorum sensing interference

Some solutions to obtain very efficient separations in isocratic and gradient modes using small particles size and ultra-high pressure.

The UHPLC strategy which combines sub-2 microm porous particles and ultra-high pressure (>1000 bar) was investigated considering very high resolution criteria in both isocratic and gradient modes, with mobile phase temperatures between 30 and 90 degrees C. In isocratic mode, experimental conditions to reach the maximal efficiency were determined using the kinetic plot representation for DeltaP(max)=1000 bar. It has been first confirmed that the molecular weight of the compounds (MW) was a critical parameter which should be considered in the construction of such curves. With a MW around 1000 g mol(-1), efficiencies as high as 300,000 plates could be theoretically attained using UHPLC at 30 degrees C. By limiting the column length to 450 mm, the maximal plate count was around 100,000. In gradient mode, the longest column does not provide the maximal peak capacity for a given analysis time in UHPLC. This was attributed to the fact that peak capacity is not only related to the plate number but also to column dead time. Therefore, a compromise should be found and a 150 mm column should be preferentially selected for gradient lengths up to 60 min at 30 degrees C, while the columns coupled in series (3x 150 mm) were attractive only for t(grad)>250 min. Compared to 30 degrees C, peak capacities were increased by about 20-30% for a constant gradient length at 90 degrees C and gradient time decreased by 2-fold for an identical peak capacity.

Conditioned polarized Caco-2 cell monolayers allow to discriminate for the ability of gut-derived microorganisms to modulate permeability and antigen-induced basophil degranulation.

BACKGROUND: Food allergy is a common allergic disorder--especially in early childhood. The avoidance of the allergenic food is the only available method to prevent further reactions in sensitized patients. A better understanding of the immunologic mechanisms involved in this reaction would help to develop therapeutic approaches applicable to the prevention of food allergy. OBJECTIVE: To establish a multi-cell in vitro model of sensitized intestinal epithelium that mimics the intestinal epithelial barrier to study the capacity of probiotic microorganisms to modulate permeability, translocation and immunoreactivity of ovalbumin (OVA) used as a model antigen. METHODS: Polarized Caco-2 cell monolayers were conditioned by basolateral basophils and used to examine apical to basolateral transport of OVA by ELISA. Activation of basophils with translocated OVA was measured by beta-hexosaminidase release assay. This experimental setting was used to assess how microorganisms added apically affected these parameters. Basolateral secretion of cytokine/chemokines by polarized Caco-2 cell monolayers was analysed by ELISA. RESULTS: Basophils loaded with OVA-specific IgE responded to OVA in a dose-dependent manner. OVA transported across polarized Caco-2 cell monolayers was found to trigger basolateral basophil activation. Microorganisms including lactobacilli and Escherichia coli increased transepithelial electrical resistance while promoting OVA passage capable to trigger basophil activation. Non-inflammatory levels of IL-8 and thymic stromal lymphopoietin were produced basolaterally by Caco-2 cells exposed to microorganisms. CONCLUSION: The complex model designed in here is adequate to learn about the consequence of the interaction between microorganisms and epithelial cells vis-a-vis the barrier function and antigen translocation, two parameters essential to mucosal homeostasis. It can further serve as a direct tool to search for microorganisms with anti-allergic and anti-inflammatory properties.