Neural progenitor cell death is induced by extracellular ATP via ligation of P2X7 receptor

Neural progenitor cells (NPCs) are capable of self-renewal and differentiation into neurons, astrocytes and oligodendrocytes, and have been used to treat several animal models of CNS disorders. In the present study, we show that the P2X7 purinergic receptor (P2X7R) is present on NPCs. In NPCs, P2X7R activation by the agonists extracellular ATP or benzoyl ATP triggers opening of a non-selective cationic channel. Prolonged activation of P2X7R with these nucleotides leads to caspase independent death of NPCs. P2X7R ligation induces NPC lysis/necrosis demonstrated by cell membrane disruption accompanied with loss of mitochondrial membrane potential. In most cells that express P2X7R, sustained stimulation with ATP leads to the formation of a non-selective pore allowing the entry of solutes up to 900 Da, which are reportedly involved in P2X7R-mediated cell lysis. Surprisingly, activation of P2X7R in NPCs causes cell death in the absence of pore formation. Our data support the notion that high levels of extracellular ATP in inflammatory CNS lesions may delay the successful graft of NPCs used to replace cells and repair CNS damage.     

Polycations. 17. Synthesis and properties of polycationic derivatives of carbohydrates

In our continuing investigation of polycationic salts for purposes of antimicrobial action, ion-channel blocking, and construction of ionic liquids, we have prepared several series of polycationic salts derived from carbohydrate precursors. These salts are currently being investigated for optimal efficacy as antibacterials and antifungals, as well as for other applications. The syntheses of such series of salts are described here along with preliminary antibacterial testing results and a discussion of their properties indicating their potential utility for several purposes.     

Phylogenetic analysis of the alpha-globin pseudogene-4 (Hba-ps4) locus in the house mouse species complex reveals a stepwise evolution of t haplotypes [published erratum appears in Mol Biol Evol 1994 Jan;11(1):158]

A parsimony analysis was performed on restriction sites at the Hba-ps4 pseudogene locus within one of four inversions associated with mouse t haplotypes. The results suggest that all t haplotypes form a monophyletic group and that the in (17)4 inversion originated before the radiation of the Mus musculus species complex but after the divergence of the lineages leading to M. spretus, M. abbotti, and M. hortulanus. A time frame based on the evolutionary rate of mouse pseudogenes places the origin of this t haplotype inversion at 1.5 Mya, or approximately 1.5 Myr after the origin of the more proximal t complex inversion, in (17)2. The accumulated evidence indicates that complete t haplotypes have been assembled in a stepwise manner, with each of these inversions occurring on separate chromosomal lineages and at different evolutionary times. In addition, the evolutionary relationships of pseudogene sequences resulting from genetic exchange between wild-type and t haplotype alleles were examined. Analysis of sequences from the 5' and 3' sides of a putative site of recombination resulted in cladograms with different topologies. The implications for hypotheses concerning the evolutionary forces acting on t haplotypes and their rapid propagation throughout worldwide populations of mice are discussed.      

Mediterranean diversification of the grass-feeding Anisopliina beetles (Scarabaeidae, Rutelinae, Anomalini) as inferred by bootstrap-averaged dispersal–vicariance analysis

Aim The circum‐Mediterranean region is one of the most complex regions of the Earth in terms of geography and natural history. The Old World species of the beetle subtribe Anisopliina (Scarabaeidae) feed almost exclusively on the pollen of grasses (Poaceae). Within this group, the ‘anisopliine clade’ forms a monophyletic group distributed mainly in the circum‐Mediterranean region. Here, we reconstruct the biogeographical history of the anisopliine beetles in relation to the diversification of grasses, and compare this reconstruction with previous hypotheses concerning the evolution of the Mediterranean fauna and with palaeogeographical accounts of the history of this region. Location The Mediterranean region, including North Africa, the Western Mediterranean, Balkans–Anatolia, Middle East and Caucasus. Methods Dispersal–vicariance analysis (diva ) was used to reconstruct ancestral distributions based on the morphological phylogeny and to infer the biogeographical processes that have shaped the observed distribution patterns. To account for phylogenetic uncertainty in the biogeographical reconstruction, we ran alternative ancestral distributions derived by diva over a sample of trees obtained by bootstrapping the original data set, reflecting the relative confidence of the ancestral areas on the various clades in the phylogeny. Results The Eastern Mediterranean region and the Caucasus are inferred as the ancestral area of most of the anisopliine lineages. The Eastern Mediterranean region is also reconstructed as the source area of the majority of dispersal events, in particular towards North Africa and the Western Mediterranean. The Iberian Peninsula is inferred as part of the ancestral distribution of the anisopliine clade but also as the setting of several independent colonization events via both the North African platform (Anthoplia) and a European dispersal route (Anisoplia). Main conclusions Our results confirm the role played by the Eastern Mediterranean as an evolutionary cradle of diversity for Mediterranean lineages. This can be explained by a recent and intense orogenic activity that might have promoted isolation and allopatric speciation within lineages. Both the Anomalini fossil record and the close association of anisopliine beetles with grasses suggest that the anisopliine clade originated in the Late Tertiary and that its spatial and temporal evolution within the Mediterranean Basin coincided with that of its major food source, the Mediterranean Poaceae.     

Intra-annual patterns of saproxylic beetle assemblages inhabiting Mediterranean oak forests

The temporal factor has been widely neglected in studies related to species distribution. However, knowing the species phenology throughout the year could be a key element in ecological studies, more so considering the current climate change framework. The intra-annual temporal patterns of the saproxylic beetle assemblage inhabiting the oak forests in the western Iberian Peninsula were evaluated in terms of species richness and composition. Moreover, we analysed the temporal patterns of species richness and body size, with respect to the abiotic factors of temperature and relative humidity. The marked seasonality of the Mediterranean weather governed, to a great extent, the temporal patterns of the assemblage, as both species richness and body size showed a positive correlation with temperature and a negative correlation with relative humidity. The high temperatures reached in August limited the activity of certain species, causing a marked decrease in species richness. The results revealed that species body size decreased in the colder months of the year and vice versa, which could fit with the inverse of Bergmann’s rule; nevertheless, studies are needed to address the contribution of species physiology and autoecology to the observed temporal patterns. Regarding species composition, the partition of beta diversity in its two components showed a constant process of species turnover throughout the year. We conclude that, due to global warming, the study of temporal patterns of assemblages is becoming all the more important, since it could significantly affect the spatio-temporal distribution of species and the interactions between them.