Programming Macrophage Inflammation Resolution: The Role of Omega-3 Polyunsaturated Fatty Acids

It was previously thought that resolution of inflammation was a passive process, but recent emerging research has identified that resolution is an active process and that dual acting lipid mediators derived from essential omega-3 polyunsaturated fatty acids (PUFAs) have both anti-inflammatory (reducing neutrophil access to the inflamed tissue) and pro-resolving (removal of apoptotic cells by macrophages in the inflamed site) actions. The objective of our study was to determine the role of omega-3 PUFAs in programming phenotypic changes in treated macrophages. The polarization of macrophages during inflammatory responses to functionally distinct phenotypes may play a role in both inflammation and resolution of inflammation following treatment with omega-3 PUFAs for chronic inflammatory diseases

Evoregions of fleas and their small mammalian hosts: Do they coincide?

Combining the biogeography and phylogenetic patterns of parasite-host associations allows a better understanding of the history of parasite–host interactions, which can be achieved via biogeographic regionalization incorporating phylogenetic information. Recently, the concepts of evoregions (regions where a majority of species evolved from one or several ancestors inhabiting these regions) and evolutionary transition zones (regions of high phylogenetic turnover) have been proposed, coupled with a classification approach for these concepts. We applied this approach to 206 flea species and 265 host species of the Palearctic and aimed to identify evoregions and evolutionary transition zones for both fleas and hosts and to understand whether these evoregions and transition zones match each other. We identified 5 evoregions with 3 transition zones for either fleas or hosts, but neither the positions and boundaries of the flea and host evoregions nor the transition zones coincided. Indications of multiple geographic centres of diversification of the same flea lineages suggested that (a) the common evolutionary history of fleas and hosts was characterized by multiple events other than codiversification and that (b) dispersal played an important role in flea and host assemblies. Barriers to dispersal could be represented by landscape features (deserts and mountain ranges) and/or climate differences

Phylogenetic Signal in Module Composition and Species Connectivity in Compartmentalized Host-Parasite Networks

Across different taxa, networks of mutualistic or antag- onistic interactions show consistent architecture. Most networks are modular, with modules being distinct species subsets connected mainly with each other and having few connections to other modules. We investigate the phylogenetic relatedness of species within modules and whether a phylogenetic signal is detectable in the within- and among-module connectivity of species using 27 mammal-flea net- works from the Palaearctic. In the 24 networks that were modular, closely related hosts co-occurred in the same module more often than expected by chance; in contrast, this was rarely the case for parasites. The within- and among-module connectivity of the same host or parasite species varied geographically. However, among-mod- ule but not within-module connectivity of host and parasites was somewhat phylogenetically constrained. These findings suggest that the establishment of host-parasite networks results from the interplay between phylogenetic influences acting mostly on hosts and local factors acting on parasites, to create an asymmetrically constrained pattern of geographic variation in modular structure. Modularity in host-parasite networks seems to result from the shared evolutionary history of hosts and by trait convergence among unrelated parasites. This suggests profound differences between hosts and parasites in the establishment and functioning of bipartite antagonistic networks.Peer reviewe

Phylogenetic patterns in regional flea assemblages from 6 biogeographic realms: strong links between flea and host phylogenetic turnovers and weak effects of phylogenetic originality on host specificity

We investigated phylogenetic patterns in flea assemblages from 80 regions in 6 biogeographic realms and asked whether (a) flea phylogenetic turnover is driven by host phylogenetic turnover, environmental dissimilarity or geographic distance; (b) the relative importance of these drivers differs between realms; and (c) the environmental drivers of flea phylogenetic turnover are similar to those of host phylogenetic turnover. We also asked whether the phylogenetic originality of a flea species correlates with the degree of its host specificity and whether the phylogenetic originality of a host species correlates with the diversity of its flea assemblages. We found that host phylogenetic turnover was the best predictor of flea phylogenetic turnover in all realms, whereas the effect of the environment was weaker. Environmental predictors of flea phylogenetic turnover differed between realms. The importance of spatial distances as a predictor of the phylogenetic dissimilarity between regional assemblages varied between realms. The responses of host turnover differed from those of fleas. In 4 of the 6 realms, geographic distances were substantially better predictors of host phylogenetic turnover than environmental gradients. We also found no general relationship between flea phylogenetic originality and its host specificity in terms of either host species richness or host phylogenetic diversity. We conclude that flea phylogenetic turnover is determined mainly by the phylogenetic turnover of their hosts rather than by environmental gradients. Phylogenetic patterns in fleas are manifested at the level of regional assemblages rather than at the level of individual species

Review of The Biogeography of Host-Parasite Interactions by Serge Morand and Boris R Krasnov

Abstract Morand, S and Krasnov, B.R. The Biogeography of Host-Parasite Interactions. Oxford University Press; 2010. 277 pages, ISBN 978-0-19-956134-6 (Hbk.), 978-0-19-956135-3 (Pbk.). Review When starting to read the book, I first decided to come back to the definition of what is biogeography? Biogeography is the study of the distribution of living organisms spatially and temporally. The scope of this multidisciplined field aims to reveal where organisms live, at what abundance, and why they are, or are not, found in a certain geographical area. The patterns of species distribution across geographical areas can usually be explained through a combination of historical factors such as speciation, extinction, continental drift and glaciation, in combination with the geographical constraints of landmass areas and isolation, and the available ecosystem energy supplies. Biogeography is also important in extrapolating the ripple effects of natural and man-made impacts on organism range and distribution. More generally, biogeography is the science that attempts to document and understand patterns of biodiversity, which means that biogeographers seek to understand the interactions between populations, species and ecological communities with their environment, in space and time. Astonishingly, consideration of population and species health and viability is still rare in biogeography whereas the role of parasites in regulating host population abundance and in exterminating local species -thus what can make one species common and even abundant, and what can make another species rare -has received much attention over the past decade. The biogeography of some hosts may be influenced by the distribution of parasites, quite apart from the abiotic influences and, in contrast, the biogeography of parasites is determined by host suitability and availability and therefore by the geographica