Arteriosclerosis in rat aortic allografts: Dynamics of cell growth,apoptosis and expression of extracellular matrix proteins

Transplant vasculopathy is a key factor behind the late loss of transplanted organs. Since effective treatment is still lacking, a further understanding of the pathology of this process is important. Here, a rat model of aortic allografts was used and analyzed by immunohistochemistry and biochemical tests. Infrarenal aortic segments were transplanted from F344 to Lewis rats and analysed after 1–12 weeks using isografts as controls. After 1 week, endothelial cells gradually disappeared at the graft lumen as shown by von Willebrand factor staining and cellular activation was detected in the adventitia and intima using cellular retinol-binding protein-1 as a marker. Subsequently, proliferating smooth muscle cells, lymphocytes and macrophages accumulated in the intima as indicated by the appearance of staining for cell- and proliferation-specific antigens (smooth muscle -actin, CD45_RC, ED1, cyclin D1 and proliferating cell nuclear antigen). After 4–8 weeks, TUNEL- and Fas-positive cells were observed in the media, denoting progressive apoptosis. In parallel, the developing neointima contained increased immunoreactivity for fibronectin and osteopontin. At the end of the observation period, an accumulation of macrophages and calcification was observed in the media and endothelial cells reappeared at the graft surface. The findings demonstrate major cellular and structural changes in the transplanted artery, including activation, proliferation and apoptosis of SMCs, and an altered composition of the extracellular matrix. Possibly, the observed changes in SMC phenotype, cell cycle and apoptosis during development of transplant arteriosclerosis are related to the expression of extracellular matrix proteins.     

Inhibition of rat smooth muscle cell adhesion and proliferation by non-anticoagulant heparins

Heparin is a well established growth inhibitor of arterial smooth muscle cells (SMCs) both in animal models and in vitro. Even though the cellular mechanisms involved in the anti-proliferative properties of heparin are being resolved, the structural requirements for the biological effects of heparin are not known in detail. Here, we have studied the effect of chemically modified heparins of different molecular weights and anticoagulant activities on proliferation and adhesion of rat aortic SMCs in vitro. The effects of native heparin (NH) and chemically modified heparins were examined after stimulation with fetal calf serum (FCS), platelet-derived growth factor BB (PDGF BB), basic fibroblast growth factor (bFGF), and heparin-binding epidermal growth factor (hbEGF) with respect to DNA synthesis and expression of phosphorylated and activated mitogen-activated protein kinase (pERK1 and 2). In a similar manner as NH, the modified heparins were capable of inhibiting activation of ERK1 and 2 and DNA synthesis induced by FCS and hbEGF whereas the modified heparins potentiated the mitogenic effect of bFGF and no compound affected PDGF BB-induced ERK activity and SMC growth. In contrast, cell adhesion to fibronectin was inhibited by NH and modified heparins in a size-dependent manner with the lowest effect by the smallest compound. The results show that heparins with varying anticoagulant activities and molecular weights but with similar sulfate content can retain anti-proliferative properties while the effect on some other biological processes such as cell adhesion is lost. Possibly, such chemical alterations may yield useful substances for the prevention of SMC proliferation after arterial injury.     

A biologically-active procyanidin from Machaerium floribundum

A procyanidin was isolated from Machaerium floribundum and characterized by its ¹³C NMR spectrum. The procyanidin consists of an average of four units, M_n = 1150, and the stereochemistry of the heterocyclic ring system is cis. The procyanidin inhibited the growth of Pseudomonas maltophilia.     

The relationships of Heberdenia bahamensis and H. penduliflora (Myrsinaceae)

A morphological and anatomical investigation is presented of the two species of Heberdenia, H. bahamensis (Macaronesia) and H. penduliflora (Mexico). A cladistic analysis including 27 taxa of the Myrsinaceae and using Jacquinia (Theophrastaceae) and Manilkara (Sapotaceae) as outgroup was performed to provide a hypothesis of the relationships of the two species of Heberdenia. It was concluded that H. bahamensis and H. penduliflora are not more closely related to each other than either is to many other species of the Myrsinaceae, and that they should not be referred to the same genus. Heberdenia bahamensis appears to be most closely related to the Old World genera Pleiomeris, Embelia , and Grenacheria , whereas H. penduliflora is nested within Ardisia s. L , possibly being most closely related to the segregate genus Gentlea. It is suggested that H. penduliflora is probably best referred to a genus of its own.     

IQGAP1 promotes CXCR4 chemokine receptor function and trafficking via EEA-1+ endosomes

IQ motif–containing GTPase-activating protein 1 (IQGAP1) is a cytoskeleton-interacting scaffold protein. CXCR4 is a chemokine receptor that binds stromal cell–derived factor-1 (SDF-1; also known as CXCL12). Both IQGAP1 and CXCR4 are overexpressed in cancer cell types, yet it was unclear whether these molecules functionally interact. Here, we show that depleting IQGAP1 in Jurkat T leukemic cells reduced CXCR4 expression, disrupted trafficking of endocytosed CXCR4 via EEA-1⁺ endosomes, and decreased efficiency of CXCR4 recycling. SDF-1–induced cell migration and activation of extracellular signal-regulated kinases 1 and 2 (ERK) MAPK were strongly inhibited, even when forced overexpression restored CXCR4 levels. Similar results were seen in KMBC and HEK293 cells. Exploring the mechanism, we found that SDF-1 treatment induced IQGAP1 binding to α-tubulin and localization to CXCR4-containing endosomes and that CXCR4-containing EEA-1⁺ endosomes were abnormally located distal from the microtubule (MT)-organizing center (MTOC) in IQGAP1-deficient cells. Thus, IQGAP1 critically mediates CXCR4 cell surface expression and signaling, evidently by regulating EEA-1⁺ endosome interactions with MTs during CXCR4 trafficking and recycling. IQGAP1 may similarly promote CXCR4 functions in other cancer cell types.     

Mesozooplankton community structure changes in the Mfolozi–Msunduzi estuarine system,South Africa,during contrasting river flow conditions

The Mfolozi–Msunduzi estuarine system is subject to periodic dry and wet cycles, with subsequent changes in the abiotic and biotic characteristics of the system. The aim of the current study was to compare its mesozooplankton composition during relatively dry and wet periods. Mesozooplankton samples were collected between 2007 and 2010 in both the Mfolozi and the Msunduzi, covering a dry period between 2007 and 2008 and a period of relatively high freshwater inputs during 2009 and 2010. High flows during the wet period reduced the densities of most of the dominant estuarine mesozooplankton taxa in the Mfolozi Estuary, such as estuarine calanoids Pseudodiaptomus stuhlmanni (Poppe & Mrázek, 1895) and Acartiella natalensis (Connell & Grindley, 1974). The Msunduzi Estuary functioned as a reservoir from which recolonisation by estuarine taxa would quickly take place after the Mfolozi was scoured by floodwaters. Densities of dominant meroplankton taxa, such as zoeae of the crab Paratylodiplax blephariskios and Macrobrachium spp., were not noticeably different in the Mfolozi–Msunduzi system between the low- and high-flow periods.     

Combining genetic and geospatial analyses to infer population extinction in mygalomorph spiders endemic to the Los Angeles region

Although hyperdiverse groups like terrestrial arthropods are almost certainly severely impacted by habitat fragmentation and destruction, few studies have formally documented such effects. In this paper, we summarize the results of a multifaceted research approach to assess the magnitude and importance of anthropogenic population extinction on the narrowly endemic trapdoor spider genus Apomastus . We used geographical information systems modeling to reconstruct the likely historical distribution of Apomastus , and used molecular phylogeographic data to discern population genetic structure and detect genetic signatures of population extinction. In combination, these complementary lines of inference support direct observations of population extinction, and lead us to conclude that population extinction via urbanization has played an important role in defining the modern-day distribution of Apomastus species. This population loss implies coincident loss of genetic and adaptive diversity within this genus, and more generally, suggests a loss of ground-dwelling arthropod population diversity throughout the Los Angeles Basin. Strategies for minimizing this loss are proposed.     

Molecular phylogenetics of the spider infraorder Mygalomorphae using nuclear rRNA genes (18S and 28S): conflict and agreement with the current system of classification

Mygalomorph spiders, which include the tarantulas, trapdoor spiders, and their kin, represent one of three main spider lineages. Mygalomorphs are currently classified into 15 families, comprising roughly 2500 species and 300 genera. The few published phylogenies of mygalomorph relationships are based exclusively on morphological data and reveal areas of both conflict and congruence, suggesting the need for additional phylogenetic research utilizing new character systems. As part of a larger combined evidence study of global mygalomorph relationships, we have gathered approximately 3.7 kb of rRNA data (18S and 28S) for a sample of 80 genera, representing all 15 mygalomorph families. Taxon sampling was particularly intensive across families that are questionable in composition-Cyrtaucheniidae and Nemesiidae. The following primary results are supported by both Bayesian and parsimony analyses of combined matrices representing multiple 28S alignments: (1) the Atypoidea, a clade that includes the families Atypidae, Antrodiaetidae, and Mecicobothriidae, is recovered as a basal lineage sister to all other mygalomorphs, (2) diplurids and hexathelids form a paraphyletic grade at the base of the non-atypoid clade, but neither family is monophyletic in any of our analyses, (3) a clade consisting of all sampled nemesiids, Microstigmata and the cyrtaucheniid genera Kiama, Acontius, and Fufius is consistently recovered, (4) other sampled cyrtaucheniids are fragmented across three separate clades, including a monophyletic North American Euctenizinae and a South African clade, (5) of the Domiothelina, only idiopids are consistently recovered as monophyletic; ctenizids are polyphyletic and migids are only weakly supported. The Domiothelina is not monophyletic. The molecular results we present are consistent with more recent hypotheses of mygalomorph relationship; however, additional work remains before mygalomorph classification can be formally reassessed with confidence-increased taxonomic sampling and the inclusion of additional character systems (more genes and morphology) are required.