The genus Macroteleia Westwood in Middle Miocene amber from Peru (Hymenoptera,Platygastridae s.l., Scelioninae)

A new species of the scelionine genus Macroteleia Westwood (Platygastridae s.l., Scelioninae) is described and figured from a female beautifully preserved in Middle Miocene amber from Peru. Macroteleia yaguarum Perrichot & Engel, sp. n., shows a unique combination of characters otherwise seen independently within its congeners. It is most similar to the modern M. surfacei Brues, but differs from it by the non-foveolate notauli, the contiguous punctures of the vertex, and the continuous propodeum. The new species is the first New World fossil of the genus, suggesting a Cretaceous origin for the group and a relatively old age of the South American, tropical African, and Australian faunas, and a younger age of the modern Holarctic faunas.     

First macrofossil evidence of a pre-Holocene thorny bamboo cf. Guadua (Poaceae: Bambusoideae: Bambuseae: Guaduinae) in south-western Amazonia (Madre de Dios — Peru)

Three fossil stem fragments collected from the banks of the Madre de Dios river in the south-western Peruvian Amazon are described and identified as Guadua sp. from their anatomical structure and gross morphology. These fossil monocots are stem fragments corresponding to a nodal region with i) circular sheath scars, ii) monopodial ramifications, iii) thorny or spiny buds or complex branches, and iv) a hollow stem structure. According to C¹⁴ radiodating and to their stratigraphic position, these fossils are older than 45,790 yr BP (Late Pleistocene) and younger than 3.12 ± 0.02 My (Late Pliocene) indicating that Guadua was present in south-western Amazonia before the first human occurrence in America, and before the Last Glacial Maximum (LGM). Since little is known regarding the origin of Guadua Kunth, a bamboo native to Central and South America and questions remain regarding the history of Guadua-dominated forests within the Amazonian lowland tropical rainforest, this work suggests an alternate interpretation for the Poaceae-rich palynological assemblages of Amazonia and may contribute to an understanding of the evolutionary history and present diversity of the vegetation of Amazonia.     

Plasmodium falciparum Adhesion on Human Brain Microvascular Endothelial Cells Involves Transmigration-Like Cup Formation and Induces Opening of Intercellular Junctions

Cerebral malaria, a major cause of death during malaria infection, is characterised by the sequestration of infected red blood cells (IRBC) in brain microvessels. Most of the molecules implicated in the adhesion of IRBC on endothelial cells (EC) are already described; however, the structure of the IRBC/EC junction and the impact of this adhesion on the EC are poorly understood. We analysed this interaction using human brain microvascular EC monolayers co-cultured with IRBC. Our study demonstrates the transfer of material from the IRBC to the brain EC plasma membrane in a trogocytosis-like process, followed by a TNF-enhanced IRBC engulfing process. Upon IRBC/EC binding, parasite antigens are transferred to early endosomes in the EC, in a cytoskeleton-dependent process. This is associated with the opening of the intercellular junctions. The transfer of IRBC antigens can thus transform EC into a target for the immune response and contribute to the profound EC alterations, including peri-vascular oedema, associated with cerebral malaria.     

Late Aquitanian mammals from Engehalde (Molasse Basin,Canton Bern,Switzerland)

The construction of the Neufeld tunnel in Bern city (2006–2008) led to the discovery of fossil mammals in the vicinity of the historical site of Engehalde. The study of the whole available sample led to the distinction of two mammal assemblages: (1) the historical level with the rhinocerotids Diaceratherium lemanense and D. aginense, and the ruminant Andegameryx cf. laugnacensis; (2) the Neufeld level with the artiodactyls Dremotherium feignouxi and Cainotherium sp., the carnivore Plesiogale angustifrons, and the glires Eucricetodon cf. aquitanicus, Peridyromys sp., and Prolagus vasconiensis. These two assemblages attest to a latest Aquitanian age (MN2b) for the last deposits of the ‘Lower Freshwater Molasse’ in the area. The palaeoecological analysis of the faunas indicates either the co-occurrence or the very short-termed succession of assorted terrestrial environments, ranging from forested habitats nearby water bodies or nearby steady rivers to open well-drained habitats within the hinterland.     

Effect of endothelin-1 on osteoblastic differentiation is modified by the level of connexin43: comparative study on calvarial osteoblastic cells isolated from Cx43+/−and Cx43+/+ mice

Bone is a dynamic tissue that undergoes a precise remodeling process involving resorptive osteoclastic cells and bone-forming osteoblastic (OB) cells. The functional imbalance of either of these cell types can lead to severe skeletal diseases. The proliferation and differentiation of OB cells play a major role in bone development and turnover. These cellular processes are coordinated by connexin43 (Cx43)-based gap-junctional intercellular communication (GJIC) and by soluble factors such as endothelin-1 (ET-1). We have used the Cx43 heterozygous (Cx43^+/−) murine model to study the possible cross-talk between Cx43 and ET-1 in cultured calvarial OB cells. On microcomputed tomographic analysis of 3-day-old pups, Cx43^+/− mice showed hypomineralized calvaria in comparison with their Cx43^+/+ littermates. Characterization of cultured OB cells clearly demonstrated the effect of the partial deletion of the Cx43 gene on its expression, on GJIC, and subsequently on OB differentiation. In this model, ET-1 (10⁻⁸ M) lost its mitogenic action in Cx43^+/− OB cells compared with Cx43^+/+ cells. Moreover, a correlation between the inhibition of cell differentiation by ET-1 and the decreased amount and function of Cx43 was found in Cx43^+/+ OB cells but not in their Cx43^+/− counterparts. Thus, as Cx43 is linked to OB differentiation, our data indicate that this mitogenic ET-1 peptide has pronounced effects on fully differentiated OB cells. With respect to roles in mechanotransduction and OB differentiation, Cx43 might modulate osteoblastic sensitivity to soluble factors.     

Glial‐cell‐mediated re‐induction of the blood‐brain barrier phenotype in brain capillary endothelial cells: A differential gel electrophoresis study

In the neurovascular unit, brain microvascular endothelial cells develop characteristic barrier features that control the molecular exchanges between the blood and the brain. These characteristics are partially or totally lost when the cells are isolated for use in in vitro blood‐brain barrier (BBB) models. Hence, the re‐induction of barrier properties is crucial for the relevance of BBB models. Although the role of astrocyte promiscuity is well established, the molecular mechanisms of re‐induction remain largely unknown. Here, we used a DIGE‐based proteomics approach to study endothelial cellular proteins showing significant quantitative variations after BBB re‐induction. We confirm that quantitative changes mainly concern proteins involved in cell structure and motility. Furthermore, we describe the possible involvement of the asymmetric dimethylarginine pathway in the BBB phenotype re‐induction process and we discuss asymmetric dimethylarginine's potential role in regulating endothelial function (in addition to its role as a by‐product of protein modification). Our results also suggest that the intracellular redox potential is lower in the in vitro brain capillary endothelial cells displaying re‐induced BBB functions than in cells with limited BBB functions.