Photographing the “Other”: Immigration and New Images of the Greek Ethnic “Self”

ABSTRACT

Significant transformations in the ways the ethnic “self” and its relationship to the “other” are perceived have led to the transgression of the two traditional poles (East and West) that were prevalent in the definition of Greekness since the creation of the Greek nation-state. By placing the photographs of immigrants published in the most popular local newspaper in Central Greece within their wider social and historical context, we can “see” that immigrants (a group that is perceived to be homogeneous and transcendental) constitute a new axis around which the negotiation of ethnic identity and otherness in Greece is now conducted.     

Is the Outgrowth of Transplant-Derived Axons Guided by Host Astrocytes and Myelin Loss?

Loss of cortical neurons may lead to sever and sometimes irreversible deficits in motor function in a number of neuropathological conditions. Absence of spontaneous axonal regeneration following trauma in the adult central nervous system (CNS) is attributed to inhibitory factors associated to the CNS white matter and to the non-permissive environment provided by reactive astrocytes that form a physical and biochemical barrier scar. Neural transplantation of embryonic neurons has been widely assessed as a potential approach to overcome the generally limited capacity of the mature CNS to regenerate axons or to generate new neurons in response to cell loss. We have recently shown that embryonic (E14) mouse motor cortical tissue transplanted into the damaged motor cortex of adult mice developed efferent projections to appropriate cortical and subcortical host targets including distant areas such as the spinal cord, with a topographical organization similar to that of intact motor cortex. Several parameters might account for the outgrowth of axonal projections from embryonic neurons within a presumably non-permissive adult brain, among which are astroglial reactions and myelin formation. In the present study, we have examined the role of astrocytes and myelin in the axonal outgrowth of transplanted neurons.Key Words: motor cortex, neuronal transplantation, embryonic cells, GFP, GFAP, PLP     

Binding of Insecticidal Crystal Proteins of Bacillus thuringiensis to the Midgut Brush Border of the Cabbage Looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), and Selection for Resistance to One of the Crystal Proteins

The susceptibility of Trichoplusia ni larvae to several Bacillus thuringiensis insecticidal crystal proteins (ICPs) was tested. Neonatal larvae proved to be susceptible to solubilized trypsin-treated CryIA(a), CryIA(b), and CryIA(c) (50% lethal concentrations [LC(50)s], 570, 480, and 320 ng/cm, respectively) but showed little susceptibility to CryIB and CryID (LC(50)s, 5,640 and 2,530 ng/cm, respectively). The toxicity of ICPs was correlated to binding to the epithelial brush border of the midgut, as revealed by immunocytochemical staining with monoclonal antibodies. In vitro binding experiments with iodinated ICPs and brush border membrane vesicles indicated that CryIA(b) and CryIA(c) share the same high-affinity binding site, whereas CryIA(a) binds to a different one. The affinities of CryIA(b) and CryIA(c) for the binding site were similar (K(d) = 3.6 and 4.7 nM, respectively), and the mean binding-site concentration was 0.71 pmol/mg of vesicle protein. Selection of a population with increasing concentrations of CryIA(b) produced 31-fold resistance in seven generations. The realized heritability (h) was 0.19. The increase of homozygosity (for resistance factors) as selection proceeded was reflected in the increase in the slopes of the dose-mortality curves. Resistance was specific for CryIA(b) and did not extend to CryIA(a) or even to CryIA(c). This result was not predicted by the binding-site model, in which CryIA(b) and CryIA(c) bind to the same high-affinity binding site. This result may suggest a more complicated relationship between in vitro binding of ICPs to specific sites in the epithelial membrane of the midgut and the in vivo toxic effect.     

Mechanisms of Blood Brain Barrier Disruption by Different Types of Bacteria,and Bacterial–Host Interactions Facilitate the Bacterial Pathogen Invading the Brain

This review aims to elucidate the different mechanisms of blood brain barrier (BBB) disruption that may occur due to invasion by different types of bacteria, as well as to show the bacteria–host interactions that assist the bacterial pathogen in invading the brain. For example, platelet-activating factor receptor (PAFR) is responsible for brain invasion during the adhesion of pneumococci to brain endothelial cells, which might lead to brain invasion. Additionally, the major adhesin of the pneumococcal pilus-1, RrgA is able to bind the BBB endothelial receptors: polymeric immunoglobulin receptor (pIgR) and platelet endothelial cell adhesion molecule (PECAM-1), thus leading to invasion of the brain. Moreover, Streptococcus pneumoniae choline binding protein A (CbpA) targets the common carboxy-terminal domain of the laminin receptor (LR) establishing initial contact with brain endothelium that might result in BBB invasion. Furthermore, BBB disruption may occur by S. pneumoniae penetration through increasing in pro-inflammatory markers and endothelial permeability. In contrast, adhesion, invasion, and translocation through or between endothelial cells can be done by S. pneumoniae without any disruption to the vascular endothelium, upon BBB penetration. Internalins (InlA and InlB) of Listeria monocytogenes interact with its cellular receptors E-cadherin and mesenchymal-epithelial transition (MET) to facilitate invading the brain. L. monocytogenes species activate NF-κB in endothelial cells, encouraging the expression of P- and E-selectin, intercellular adhesion molecule 1 (ICAM-1), and Vascular cell adhesion protein 1 (VCAM-1), as well as IL-6 and IL-8 and monocyte chemoattractant protein-1 (MCP-1), all these markers assist in BBB disruption. Bacillus anthracis species interrupt both adherens junctions (AJs) and tight junctions (TJs), leading to BBB disruption. Brain microvascular endothelial cells (BMECs) permeability and BBB disruption are induced via interendothelial junction proteins reduction as well as up-regulation of IL-1α, IL-1β, IL-6, TNF-α, MCP-1, macrophage inflammatory proteins-1 alpha (MIP1α) markers in Staphylococcus aureus species. Streptococcus agalactiae or Group B Streptococcus toxins (GBS) enhance IL-8 and ICAM-1 as well as nitric oxide (NO) production from endothelial cells via the expression of inducible nitric oxide synthase (iNOS) enhancement, resulting in BBB disruption. While Gram-negative bacteria, Haemophilus influenza OmpP2 is able to target the common carboxy-terminal domain of LR to start initial interaction with brain endothelium, then invade the brain. H. influenza type b (HiB), can induce BBB permeability through TJ disruption. LR and PAFR binding sites have been recognized as common routes of CNS entrance by Neisseria meningitidis. N. meningitidis species also initiate binding to BMECs and induces AJs deformation, as well as inducing specific cleavage of the TJ component occludin through the release of host MMP-8. Escherichia coli bind to BMECs through LR, resulting in IL-6 and IL-8 release and iNOS production, as well as resulting in disassembly of TJs between endothelial cells, facilitating BBB disruption. Therefore, obtaining knowledge of BBB disruption by different types of bacterial species will provide a picture of how the bacteria enter the central nervous system (CNS) which might support the discovery of therapeutic strategies for each bacteria to control and manage infection.     

Insights into Positive and Negative Requirements for Protein-Protein Interactions by Crystallographic Analysis of the β-Lactamase Inhibitory Proteins BLIP, BLIP-I, and BLP

β-Lactamase inhibitory protein (BLIP) binds a variety of β-lactamase enzymes with wide-ranging specificity. Its binding mechanism and interface interactions are a well-established model system for the characterization of protein-protein interactions. Published studies have examined the binding of BLIP to diverse target β-lactamases (e.g., TEM-1, SME-1, and SHV-1). However, apart from point mutations of amino acid residues, variability on the inhibitor side of this enzyme-inhibitor interface has remained unexplored. Thus, we present crystal structures of two likely BLIP relatives: (1) BLIP-I (solved alone and in complex with TEM-1), which has β-lactamase inhibitory activity very similar to that of BLIP; and (2) β-lactamase-inhibitory-protein-like protein (BLP) (in two apo forms, including an ultra-high-resolution structure), which is unable to inhibit any tested β-lactamase. Despite categorical differences in species of origin and function, BLIP-I and BLP share nearly identical backbone conformations, even at loop regions differing in BLIP.We describe interacting residues and provide a comparative structural analysis of the interactions formed at the interface of BLIP-I·TEM-1 versus those formed at the interface of BLIP·TEM-1. Along with initial attempts to functionally characterize BLP, we examine its amino acid residues that structurally correspond to BLIP/BLIP-I binding hotspots to explain its inability to bind and inhibit TEM-1. We conclude that the BLIP family fold is a robust and flexible scaffold that permits the formation of high-affinity protein-protein interactions while remaining highly selective. Comparison of the two naturally occurring, distinct binding interfaces built upon this scaffold (BLIP and BLIP-I) shows that there is substantial variation possible in the subnanomolar binding interaction with TEM-1. The corresponding (non-TEM-1-binding) BLP surface shows that numerous favorable backbone-backbone/backbone-side-chain interactions with a protein partner can be negated by the presence of a few, strongly unfavorable interactions, especially electrostatic repulsions.     

Comparative Study of the Absorption,Plasma Levels,and Urinary Excretion of the “New” and the “Old” Lanoxin

A comparative study was performed of the absorption, the plasma level at equilibrium, and the urinary excretion of digoxin using two types of Lanoxin tablets, those produced before and after the 1972 alteration of the tablet manufacture.After a single dose the absorption rate of the new tablets was about twice as great as the old, both in young subjects and in the elderly patients. There were no significant differences in the plasma levels of digoxin for the two tablets 15 hours after the last administration in patients on an equal maintenance dose. The urinary excretion of digoxin increased about 40% when the “old” Lanoxin was replaced by the “new.” In elderly patients a daily dose of 0·125 mg twice daily of the new tablets should be sufficient to reach the therapeutic range. Young people need a higher dosage. If the kidney function is reduced by as much as 50% the dose should be reduced.     

The Relative Significance of Host–Habitat,Depth, and Geography on the Ecology,Endemism, and Speciation of Coral Endosymbionts in the Genus Symbiodinium

Dinoflagellates in the genus Symbiodinium are among the most abundant and important group of eukaryotic microbes found in coral reef ecosystems. Recent analyses conducted on various host cnidarians indicated that Symbiodinium assemblages in the Caribbean Sea are genetically and ecologically diverse. In order to further characterize this diversity and identify processes important to its origins, samples from six orders of Cnidaria comprising 45 genera were collected from reef habitats around Barbados (eastern Caribbean) and from the Mesoamerican barrier reef off the coast of Belize (western Caribbean). Fingerprinting of the ribosomal internal transcribed spacer 2 identified 62 genetically different Symbiodinium. Additional analyses of clade B Symbiodinium using microsatellite flanker sequences unequivocally characterized divergent lineages, or “species,” within what was previously thought to be a single entity (B1 or B184). In contrast to the Indo-Pacific where host-generalist symbionts dominate many coral communities, partner specificity in the Caribbean is relatively high and is influenced little by the host’s apparent mode of symbiont acquisition. Habitat depth (ambient light) and geographic isolation appeared to influence the bathymetric zonation and regional distribution for most of the Symbiodinium spp. characterized. Approximately 80% of Symbiodinium types were endemic to either the eastern or western Caribbean and 40–50% were distributed to compatible hosts living in shallow, high-irradiance, or deep, low-irradiance environments. These ecologic, geographic, and phylogenetic patterns indicate that most of the present Symbiodinium diversity probably originated from adaptive radiations driven by ecological specialization in separate Caribbean regions during the Pliocene and Pleistocene periods.     

Effect of Starvation,Refeeding and Hydrocortisone Administration on Turnover of Myofibrillar Proteins Estimated by Urinary Excretion of Nτ-Methylhistidine in the Rat

Quantitative changes in fractional catabolic and synthetic rates of the myosin-actin pool in rat muscle under starvation and refeeding, during growth or after treatment with hydrocortisone were studied by estimating urinary excretion of N^τ-methylhistidine (3-methyl- histidine; Me-His).

Following deprivation of food, urinary Me-His output increased from 0.35 mg/day to 0.45 mg/day during first 2 day in spite of decreasing body Me-His pool. This high rate of Me-His excretion was maintained for the following 4 days of starvation and then decreased. When rats were refed a 20% casein diet after 10 days of starvation, Me-His excretion continued to decrease even after 3 days of refeeding. On the fifth day of refeeding, it began to rise progressively. During starvation, fractional catabolic rate of myosin-actin was about 3.7 %/day in comparison with 2.6 %/day of fed rats. After refeeding, the fractional catabolic rate decreased rapidly to a minimum value of 1.7 %/day on the third day. After that, it reached to a value of 2.6 %/day of fed rats. On the other hand, fractional synthetic rate of myosin-actin dropped immediately after fasting and the low rate of about 0.4 %/day was maintained during starvation period. Fractional synthetic rate recovered quickly after refeeding.

Urinary output of nitrogen and creatinine rose quickly on the first day after administration of hydrocortisone and on the second day it fell to their normal value. While Me-His excretion increased after injection of hydrocortisone up to 0.52 mg/day on the second day and this high excretion rate remained until the following day. From these results, it was shown that administration of hydrocortisone to rats enhances catabolism and reduces synthesis of myosin-actin. The results also show that the effect of this hormone on myofibrillar protein catabolism appears to last longer than its effect on nitrogen metabolism in the whole body judged from urinary nitrogen output.

Fractional rates of catabolism and synthesis of rat myosin-actin were 3.3 %/day (half- life of 21 days) and 7.2%/day, respectively, at the growth stage of 129 g body weight. These rates were 2.3 %/day (half-life of 30 days) and 2.8 %/day, respectively, at the mature stage of 363 g body weight.

Under the dietary conditions in this experiment, fractional synthetic rate changed far more dramatically than catabolic rate. This suggests that mass of muscle protein is primarily regulated by the rate of synthesis, although the rate of catabolism should not be neglected.     

Sensory cells of the “rod-” and “cone-type” in the pineal organ of Rana esculenta,as revealed by immunoreaction against opsin and by the presence of an oil (lipid) droplet

Summary The pineal organ of the frog, Rana esculenta, was studied by use of light- and electron-microscopic methods including immunoreaction against opsin. Most of the morphologically classified cone-type outer segments of the pineal photoreceptors reacted with antisera against opsin of the bovine retina that is dominated by rods. Some of the outer segments of pineal photoreceptor cells remained unstained in accord with the reference tissue, the frog retina, where generally the rods were opsin-positive and most of the cones opsin-negative.The opsin-negative outer segments of pineal photoreceptors were found in continuity with inner segments each containing a large oil (lipid) droplet. These oil droplets stained intensely with osmic acid, Sudan III, Sudan Black B or Scharlach R in cryostat sections, and were soluble in lipid solvents. In ultrathin sections of osmicated material, the oil droplets were homogeneous and of varying electron density. Approximately one tenth of the pineal photoreceptors contained oil droplets and at the same time possessed opsin-immunonegative outer segments.Since in the retina oil droplets and a negative immunoreaction against bovine opsin are characteristic of cones, we suggest that in the pineal organ they also mark conetype photoreceptors scattered among rod-type photo-receptors, the latter displaying a positive immunoreaction with the antisera used.Support from the Deutsche Forschungsgemeinschaft (Ok 1/25-3) is gratefully acknowledged     

Factors involved in the colonisation of building façades by algae and cyanobacteria in France

Algae and cyanobacteria are colonisers of building fa?ades. A multivariate analysis of data gathered during a sampling campaign around France proved that precipitation, hygrometry, thermal amplitude, distance from the sea and proximity to vegetation were environmental parameters influencing this colonisation. Other influencing factors could be attributed to the nature of the fa?ade coating, mineral substrata being more frequently colonised, and to the architecture, favouring in some cases the formation of damp conditions and thus the colonisation of the building envelope.     

The “Multi” of Drug Resistance Explained by Oscillating Drug Transporters,Drug–Membrane Physical Interactions and Spatial Dimensionality

Multi-drug resistance (MDR) can be explained by a drug handling-type activity. In this context it is also necessary to consider the multi-specificity between drugs and drug transporters in order to explain MDR. Accordingly, the efficiency of drug efflux in MDR has always been a conceptual problem in biochemistry. Indeed, how one protein can expel, from cells, hundreds of compounds with high specificity is still controversial today. To safeguard the notion of biochemical specificity, many studies have suggested alternative mechanisms to Pgp-mediated drug resistance, which do not involve the handling of drugs. However, none of these studies have definitively ruled out the possibility concept of drug handling. Thus, until now it was not possible to imagine MDR without drug-transporter affinity or specificity. However, drug-transporter affinity is not always needed to generate what appears to be a very efficient chemical reaction. Indeed, based on the fact that bi-dimensional diffusion properties (i.e. diffusion in the membrane) are paramount to explain drug pumping-mediated MDR, it is possible to suggest how specific mathematical properties of random motions can be used to construct a model of Pgp-MDR, providing that Pgp oscillates between open/drug-accepting and closed/drug-expelling conformations. This different viewpoint highlights the fact that the multi-specificity of drug transporters and the “vacuum cleaner” hypothesis may actually be two sides of the same coin, both explained by the diffusion properties of drugs in the membrane. After retrieving basic results, predictions will be highlighted. Finally, the coherence of this model in the context of cancer biology will be discussed further.     

The nuclei of cellular organelles and the formation of daughter organelles by the “plastid-dividing ring”

It has been established that organelles, such as mitochondria and plastids, contain organelle-specific DNA and arise from the division of pre-existing organelles (e.g., Possingham and Lawrence, 1983). We propose that organelle DNAs, such as mitochondrial DNA and plastid DNA are not naked in organellesin situ but are organized in each case to form an “organelle nucleus” with basic proteins (Kuroiwa, 1982). The concept of organelle nuclei has changed our ideas about the division of organelles. Thus, the process of organelle division must be composed of two main events: division of the organelle nucleus and organellekinesis (division of the other components of the mitochondrion or plastid). The latter term has been adopted as an appropriate analogue of cytokinesis. We were the first to identify the plastid-dividing ring (PD-ring), which is located in the cytoplasm close to the outer envelope membrane at the constricted isthmus of dividing chloroplasts in the red algaCyanidium caldirum. The PD-ring is about 60 nm in width and 25 nm in thickness, and is a circular bundle of actin-like, fine filaments, each about 4–5 nm in diameter. Since cytochalasin B, an inhibitor of polymerization of actin filaments, inhibits the formation of the PD-ring and, thus, prevents subsequent division of chloroplasts, the PD-ring is thought to be a structure that is essential for the division of plastids (plastidkinesis). The behavior of the PD-ring during a cycle of chloroplast division can be classified into the following four stages on the basis of morphological and temporal differences. The chloroplast growth stage: the small, spherical chloroplast increases in volume and becomes a football-like structure, while the PD-ring from the previous division disappears. Formation of the PD-ring: the somewhat electron-dense body (see below) is fragmented into many, somewhat electron-dense granules, which are aligned along the equatorial region of the chloroplast and fine filaments are formed from the somewhat electron-dense granules in the equatorial region. The fine filaments of the PD-ring align themselves according to the longest axis of their overall domain, i.e., circumferentially. Contraction stage: a bundle of fine filaments begins to contract and generates a deep furrow. Conversion stage: after chloroplast division, the remnants of the PD-ring are converted into somewhat electron-dense bodies. Similar events occur during the second cycle of chloroplast division. Since similar structures are observed extensively in the plastids of algae, moss and higher plants, the PD-ring appears to be an essential structure for the division of plastids in plants.     

Facilitation of memory retrieval by the “anti-addictive” alkaloid,ibogaine

Anecdotal observations in humans indicate that indole alkaloid ibogaine may have antiaddictive properties. It has been suggested that the therapeutic action of ibogaine may depend upon facilitated access to the past experiences, purportedly influencing the initiation of drug addiction. To determine if ibogaine may facilitate memory retrieval, rats were trained in the Morris maze spatial navigation task. It has been found that ibogaine (0.25 or 2.5 mg/kg) or O-desmethyl-ibogaine (2.5 mg/kg) but not t-Butyl ibogaine, administered just before the test trial, facilitated spatial memory retrieval compared to rats receiving placebo treatment. It is concluded that although previously described NMDA receptor antagonistic properties of ibogaine may represent a locus for at least some of its actions, other mechanisms, involving facilitation of memory retrieval may be of importance for its anti-addictive effects.     

Deciphering the “Fuzzy” Interaction of FG Nucleoporins and Transport Factors Using Small-Angle Neutron Scattering

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“Changing by doubling”, the impact of Whole Genome Duplications in the evolution of eukaryotes

Species are usually defined by reproductive isolation and are characterized by their gene repertoire. These two aspects are consequences of events fixed during evolution, including whole genome duplications and other polyploidizations. Thanks to the recent progress in genome sequencing, new light has been shed on these events. In this review, we will summarize these findings and discuss the methodology involved. Evolutionary traces of such events have been evidenced in various lineages in plants, animals, fungi and protozoa. Comparative analysis of synteny is a powerful approach to unveil evolutionary footprints of these events. According to expectations, these events would facilitate speciation since some of them are thought to be at the base of major radiations such as teleostei or eudicotyledons. After an initial amplification, the gene repertoire would be shaped by constraints such as expression level and functional interactions that would tend to maintain only a tiny fraction of the duplicates over the long term. Functional innovation from duplication may be a secondary effect, enabled by these duplicate retention mechanisms. To cite this article: O. Jaillon et al., C. R. Biologies 332 (2009).