DNA hybridization evidence for the principal lineages of hummingbirds (Aves:Trochilidae)

The spectacular evolutionary radiation of hummingbirds (Trochilidae) has served as a model system for many biological studies. To begin to provide a historical context for these investigations, we generated a complete matrix of DNA hybridization distances among 26 hummingbirds and an outgroup swift (Chaetura pelagica) to determine the principal hummingbird lineages. FITCH topologies estimated from symmetrized delta TmH-C values and subjected to various validation methods (bootstrapping, weighted jackknifing, branch length significance) indicated a fundamental split between hermit (Eutoxeres aquila, Threnetes ruckeri; Phaethornithinae) and nonhermit (Trochilinae) hummingbirds, and provided strong support for six principal nonhermit clades with the following branching order: (1) a predominantly lowland group comprising caribs (Eulampis holosericeus) and relatives (Androdon aequatorialis and Heliothryx barroti) with violet-ears (Colibri coruscans) and relatives (Doryfera ludovicae); (2) an Andean-associated clade of highly polytypic taxa (Eriocnemis, Heliodoxa, and Coeligena); (3) a second endemic Andean clade (Oreotrochilus chimborazo, Aglaiocercus coelestis, and Lesbia victoriae) paired with thorntails (Popelairia conversii); (4) emeralds and relatives (Chlorostilbon mellisugus, Amazilia tzacatl, Thalurania colombica, Orthorhyncus cristatus and Campylopterus villaviscensio); (5) mountain-gems (Lampornis clemenciae and Eugenes fulgens); and (6) tiny bee-like forms (Archilochus colubris, Myrtis fanny, Acestrura mulsant, and Philodice mitchellii). Corresponding analyses on a matrix of unsymmetrized delta values gave similar support for these relationships except that the branching order of the two Andean clades (2, 3 above) was unresolved. In general, subsidiary relationships were consistent and well supported by both matrices, sometimes revealing surprising associations between forms that differ dramatically in plumage and bill morphology. Our results also reveal some basic aspects of hummingbird ecologic and morphologic evolution. For example, most of the diverse endemic Andean assemblage apparently comprises two genetically divergent clades, whereas the majority of North American hummingbirds belong a single third clade. Genetic distances separating some morphologically distinct genera (Oreotrochilus, Aglaiocercus, Lesbia; Myrtis, Acestrura, Philodice) were no greater than among congeneric (Coeligena) species, indicating that, in hummingbirds, morphological divergence does not necessarily reflect level of genetic divergence.      

First record of a spiral form of Aulacoseira,A. ambigua f. japonica (F.Meister) Tuji & D.M.Williams,in South African fresh waters

Water quality and algal populations in the Vaal River Barrage Reservoir have been monitored extensively for many decades, because of its importance as a water source for the most densely populated area in South Africa. Although Aulacoseira granulata (Ehrenberg) Simonsen is frequently found and at it times dominates algal assemblages in the Barrage, Aulacoseira ambigua (F.Meister) Tuji & D.M.Williams has never before been recorded at this locality. During a countrywide proficiency-testing scheme for algae counting, coordinated by Rand Water, spiral-shaped diatom colonies with distinctly curved cells were detected during May 2015. Upon investigation, it was found that the spiral colonies were Aulacoseira ambigua f. japonica, its presence in the fresh waters of South Africa being recorded for the first time. Since their first appearance during May 2015, colonies of Aulacoseira ambigua f. japonica have been constantly present in the surface waters of the Barrage. Their presence at this site can be linked to increasing eutrophication in the Vaal River, because the spiral form is known to prefer eutrophic conditions. Centric diatoms rarely form spiral colonies and there is some confusion in the literature as to the identity of this particular form, therefore in this paper we discuss this taxon, its nomenclature and ecological significance.     

Occurrence of an Environmental Acinetobacter baumannii Strain Similar to a Clinical Isolate in Paleosol from Croatia

Over the past decade, bacteria of the genus Acinetobacter have emerged as a leading cause of hospital-acquired infections. Outbreaks of Acinetobacter infections are considered to be caused exclusively by contamination and transmission in hospital environments. The natural habitats of clinically important multiresistant Acinetobacter spp. remain to be defined. In this paper, we report an incidental finding of a viable multidrug-resistant strain of Acinetobacter baumannii, related to clinical isolates, in acid paleosol from Croatia. The environmental isolate of A. baumannii showed 87% similarity to a clinical isolate originating from a hospital in this geographic area and was resistant to gentamicin, trimethoprim-sulfamethoxazole, ciprofloxacin, and levofloxacin. In paleosol, the isolate was able to survive a low pH (3.37), desiccation, and a high temperature (50°C). The probable source of A. baumannii in paleosol is illegally disposed waste of external origin situated in the abandoned quarry near the sampling site. The bacteria could have been leached from waste by storm water and thus infiltrated the paleosol.     

Phagomimetic Action of Antimicrobial Agents

A wide variety of extracted and synthesised drug molecules have electron transfer capabilities which allow them to generate reactive oxygen species (ROS). In particular, many antibiotics that kill or Inhibit bacteria, yeasts and cancer cells readily transfer electrons to oxygen making superoxide and hydrogen peroxide in the process. When suitable redox active forms of iron are available, Fenton chemistry occurs generating the highly damaging hydroxyl radical. This type of chemistry is very similar to that which evolved within phago-cytic cells as part of their microbial killing armoury. Many antibiotics, when used in model systems, have well defined pharmacological actions against key cellular functions, but their clinical usefulness is also often demonstrable at concentrations in vivo well below their in vitro minimum inhibitory concentrations. These observations have led us to propose that a common mechanism exists whereby phagocytic cells and antibiotics exploit the use of ROS for microbial killing.     

NADPH Oxidase 1 Controls the Persistence of Directed Cell Migration by a Rho-Dependent Switch of α2/α3 Integrins

NADPH oxidase 1 (Nox1) is expressed mainly in colon epithelial cells and produces superoxide ions as a primary function. We showed that Nox1 knockdown inhibits directional persistence of migration on collagen I. This paper dissects the mechanism by which Nox1 affects the direction of colonic epithelial cell migration in a two-dimensional model. Transient activation of Nox1 during cell spreading on collagen 1 temporarily inactivated RhoA and led to efficient exportation of α2β1 integrin to the cell surface, which supported persistent directed migration. Nox1 knockdown led to a loss of directional migration which takes place through a RhoA-dependent α2/α3 integrin switch. Transient RhoA overactivation upon Nox1 inhibition led to transient cytoskeletal reorganization and increased cell-matrix contact associated with a stable increase in α3 integrin cell surface expression. Blocking of α3 integrin completely reversed the loss of directional persistence of migration. In this model, Nox1 would represent a switch between random and directional migration through RhoA-dependent integrin cell surface expression modulation.The two well-recognized defining hallmarks of cancer are uncontrolled proliferation and invasion (14). The conversion of a static primary tumor into an invasive disseminating metastasis involves an enhanced migratory ability of the tumor cells. Tumor cells use migration mechanisms that are similar, if not identical, to those that occur in normal cells during physiological processes such as embryonic morphogenesis, wound healing, and immune-cell trafficking (10). To migrate, cells must acquire a spatial asymmetry that enables them to turn intracellularly generated forces into net cell body translocation. Dynamic assembly and disassembly of integrin-mediated adhesion and cytoskeletal reorganization are necessary for efficient migration (29). Integrins are heterodimeric integral membrane proteins composed of an α chain and a β chain. Depending on the cell type and extracellular matrix (ECM) substrate, focal contact assembly and migration can be regulated by different integrins. Collagen receptors include α1β1, α2β1, and α3β1 integrins. α1β1 and α3β1 integrins also bind laminin and have less affinity for collagen than does integrin α2β1 (47). The intrinsic propensity of cells to continue migrating in the same direction without turning is closely related to integrin/cytoskeletal interaction, which is known to regulate tractional forces, resulting in modulation of the speed and direction of cell migration (33). Interestingly, different integrin-ECM associations might have opposite effects on the regulation of the directionality of migration. Danen et al. have shown that adhesion to fibronectin by αvβ3 promotes persistent migration through activation of the actin-severing protein cofilin, which results in a polarized phenotype with a single broad lamellipod at the leading edge. In contrast, adhesion to fibronectin by α5β1 instead leads to phosphorylation/inactivation of cofilin and these cells fail to polarize their cytoskeleton and adopt a random/nonpersistent mode of migration (5). Members of the Rho GTPase family (including RhoA, Rac1, and Cdc42) are known as key modulators of cytoskeletal dynamics that occur during cell migration (37). RhoA regulates stress fiber and focal adhesion assembly, Rac regulates the formation of lamellipodial protrusions and membrane ruffles, and Cdc42 triggers filopodial extensions at the cell periphery (13).One of the earliest characterized functions of the Rho GTPase Rac was regulation of the activity of the NADPH oxidase complex in phagocytic cells to produce reactive oxygen species (ROS) (1, 19). Moreover, it has been shown that Rac-dependent ROS production leads to downregulation of RhoA through oxidative inactivation of the low-molecular-weight (LMW) protein tyrosine phosphatase (PTP) and the subsequent activation of p190RhoGAP (31). ROS are also known to directly affect important regulators of cell migration such as PTEN, FAK, or Src (4, 20, 22). ROS are generated in cells from several sources, including the mitochondrial respiratory chain, xanthine oxidase, cytochrome P450, nitric oxide synthase, and NADPH oxidase. The seven known human catalytic subunits of NADPH oxidase include Nox1 to -5 and Duox1 and -2, with Nox2 (gp91phox) being the founding member (21). These oxidases participate in several adaptive functions, ranging from mitogenesis to immune cell signaling (11). A growing body of data points to a key role for ROS production by NADPH oxidase in the control of cell migration and cytoskeletal reorganization (30, 44). Among NADPH oxidase homologs, Nox1 has been detected in different cell types, with major expression in vascular smooth muscle cells and colonic epithelial cells (42). Nox1 involvement in the control of cytoskeletal organization and cellular migration has been only recently reported. Shinohara et al. demonstrated that oncogenic Ras transformation involves Nox1-dependent signaling and leads to inactivation of RhoA. Abrogation of Nox1-dependent ROS production by diphenyleneiodonium (DPI) or small interfering RNA restores RhoA activation and actin stress fiber formation (41). More recently, several groups have highlighted a key role of Nox1 in the control of growth factor-induced migration (16, 38, 40). Cancer cells probably undergo random migration during metastasis, but their migration can be directed by cytokine gradients and/or associated with ECM fibers (29, 55). In a recent report, we showed that Nox1 downregulation decreased the persistence of colonic adenocarcinoma cell migration over collagen I (Col-I) without affecting either the mean velocity or the total distance of migration.In the present study, we investigated the molecular mechanism by which Nox1-dependent ROS production controls the directionality of migration of colonic adenocarcinoma cells. We showed that Nox1-dependent ROS production, which occurs during cell spreading after 4 h of adhesion to Col-I, transiently inhibited RhoA activity. Nox1 inhibition during cell spreading led to a transient increase in cell-matrix contact and initiated a sustained decrease in α2β1 integrin cell surface expression, which was compensated for by an increase in α3 integrin cell surface expression. While Nox1-dependent RhoA inhibition was transient, the observed α2/α3 integrin switch was sustained over 24 h. The loss of directionality observed in cell migration upon Nox1 inhibition may be reversed by α3 integrin blockade. This work shows that Nox1 is involved in the control of integrin surface expression during migration on Col-I, which is critical for persistent directed migration through transient modulation of a RhoA/ROCK-dependent pathway.     

7th SOSORT consensus paper: conservative treatment of idiopathic & Scheuermann's kyphosis

Abstract

Thoracic hyperkyphosis is a frequent problem and can impact greatly on patient's quality of life during adolescence. This condition can be idiopathic or secondary to Scheuermann disease, a disease disturbing vertebral growth. To date, there is no sound scientific data available on the management of this condition. Some studies discuss the effects of bracing, however no guidelines, protocols or indication's of treatment for this condition were found. The aim of this paper was to develop and verify the consensus on managing thoracic hyperkyphosis patients treated with braces and/or physiotherapy.

Methods

The Delphi process was utilised in four steps gradually modified according to the results of a set of recommendations: we involved the SOSORT Board twice, then all SOSORT members twice, with a Pre-Meeting Questionnaire (PMQ), and during a Consensus Session at the SOSORT Lyon Meeting with a Meeting Questionnaire (MQ).

Results

There was an unanimous agreement on the general efficacy of bracing and physiotherapy for this condition. Most experts suggested the use of 4-5 point bracing systems, however there was some controversy with regards to physiotherapeutic aims and modalities.

Conclusion

The SOSORT panel of experts suggest the use of rigid braces and physiotherapy to correct thoracic hyperkyphosis during adolescence. The evaluation of specific braces and physiotherapy techniques has been recommended.