What uses are mating types? The "developmental switch" model.

Why mating types exist at all is subject to much debate. Among hypotheses, mating types evolved to control organelle transmission during sexual reproduction, or to prevent inbreeding or same-clone mating. Here I review data from a diversity of taxa (including ciliates, algae, slime molds, ascomycetes, and basidiomycetes) to show that the structure and function of mating types run counter the above hypotheses. I argue instead for a key role in triggering developmental switches. Genomes must fulfill a diversity of alternative programs along the sexual cycle. As a haploid gametophyte, an individual may grow vegetatively (through haploid mitoses), or initiate gametogenesis and mating. As a diploid sporophyte, similarly, it may grow vegetatively (through diploid mitoses) or initiate meiosis and sporulation. Only diploid sporophytes (and not haploid gametophytes) should switch on the meiotic program. Similarly, only haploid gametophytes (not sporophytes) should switch on gametogenesis and mating. And they should only do so when other gametophytes are ready to do the same in the neighborhood. As argued here, mating types have evolved primarily to switch on the right program at the right moment.

The hourglass and the early conservation models--co-existing patterns of developmental constraints in vertebrates.

Developmental constraints have been postulated to limit the space of feasible phenotypes and thus shape animal evolution. These constraints have been suggested to be the strongest during either early or mid-embryogenesis, which corresponds to the early conservation model or the hourglass model, respectively. Conflicting results have been reported, but in recent studies of animal transcriptomes the hourglass model has been favored. Studies usually report descriptive statistics calculated for all genes over all developmental time points. This introduces dependencies between the sets of compared genes and may lead to biased results. Here we overcome this problem using an alternative modular analysis. We used the Iterative Signature Algorithm to identify distinct modules of genes co-expressed specifically in consecutive stages of zebrafish development. We then performed a detailed comparison of several gene properties between modules, allowing for a less biased and more powerful analysis. Notably, our analysis corroborated the hourglass pattern at the regulatory level, with sequences of regulatory regions being most conserved for genes expressed in mid-development but not at the level of gene sequence, age, or expression, in contrast to some previous studies. The early conservation model was supported with gene duplication and birth that were the most rare for genes expressed in early development. Finally, for all gene properties, we observed the least conservation for genes expressed in late development or adult, consistent with both models. Overall, with the modular approach, we showed that different levels of molecular evolution follow different patterns of developmental constraints. Thus both models are valid, but with respect to different genomic features.

Deletion of human GP1BB and SEPT5 is associated with Bernard-Soulier syndrome, platelet secretion defect, polymicrogyria, and developmental delay.

The bleeding disorder Bernard-Soulier syndrome (BSS) is caused by mutations in the genes coding for the platelet glycoprotein GPIb/IX receptor. The septin SEPT5 is important for active membrane movement such as vesicle trafficking and exocytosis in non-dividing cells (i.e. platelets, neurons). We report on a four-year-old boy with a homozygous deletion comprising not only glycoprotein Ibβ (GP1BB) but also the SEPT5 gene, located 5' to GP1BB. He presented with BSS, cortical dysplasia (polymicrogyria), developmental delay, and platelet secretion defect. The homozygous deletion of GP1BB and SEPT5, which had been identified by PCR analyses, was confirmed by Southern analyses and denaturing HPLC (DHPLC). The parents were heterozygous for this deletion. Absence of GPIbβ and SEPT5 proteins in the patient's platelets was illustrated using transmission electron microscopy. Besides decreased GPIb/IX expression, flow cytometry analyses revealed impaired platelet granule secretion. Because the bleeding disorder was extremely severe, the boy received bone marrow transplantation (BMT) from a HLA-identical unrelated donor. After successful engraftment of BMT, he had no more bleeding episodes. Interestingly, also his mental development improved strikingly after BMT. This report describes for the first time a patient with SEPT5 deficiency presenting with cortical dysplasia (polymicrogyria), developmental delay, and platelet secretion defect.

The Poor Representation of the Poor in a Comparative Perspective

Due to diverging levels of political influence of various income groups, political institutions likely reflect¦the policy preferences of certain groups of citizens better than others, independently of their numerical¦weight. This runs counter the egalitarian principle of 'one citizen, one vote'. The present article documents¦a general trend of underrepresentation of the preferences of relatively poor citizens both by¦parties and by governments across Western democracies, although important cross-national differences¦exist.

An evolutionary perspective on self-organized division of labor in social insects

Division of labor is a complex phenomenon observed throughout nature. Theoretical studies have focused either on its emergence through self-organization mechanisms or on its adaptive consequences. We suggest that the interaction of self-organization, which undoubtedly characterizes division of labor in social insects, and evolution should be further explored. We review the factors empirically shown to influence task choice. In light of these factors, we review the most important self-organization and evolutionary models for division of labor and outline their advantages and limitations. We describe ways to unify evolution and self-organization in the theoretical study of division of labor and recent results in this area. Finally, we discuss some benchmarks and primary challenges of this approach.

Denervation rénale endovascu- laire par radiofréquence: perspective d'un traitement prometteur de l'hypertension artérielle [Renal sympathetic denervation: perspective of a promising treatment for hypertension].

The crucial role of the sympathetic nervous system activity in the initiation and maintenance of hypertension was already in mind in the 1920s when surgical options were proposed to severely hypertensive patients. Despite constant evolution of pharmacological treatments, one estimates that 15-30% of hypertensive patients are still not well controlled and present resistant hypertension. The development of a new endovascular catheter used for selective sympathetic renal denervation by radiofrequency offers new perspectives of treatment. Encouraged by the recent results of the first clinical trials in a targeted population, this procedure could be used in some more indications in the future. However, long term morbidity and mortality of this technique are still not known.

Freud, l'art moderne et les "misérables cannibales nus": une perspective décalée sur le destin des pulsions

La «modernité» de la psychanalyse, comme entreprise à la fois thérapeutique et de savoir, dépend-elle, pour tout ou partie, du fond animique prétendument archaïque ou primitif défini par cette discipline comme son principal objet d'étude? Rapportée à l'horizon épistémique de la psychanalyse, cette articulation entre archaïsme et modernité aurait-elle seulement été du goût de Freud? En interrogeant de manière critique les rapports de Freud à l'art «moderne», à l'art «classique» et aux arts «primitifs», ce texte entend simultanément mettre en évidence l'importance du paradigme des arts dans la constitution de l'identité épistémique de la psychanalyse et proposer une possible relecture des relations entre nature et culture ou du phénomène de sublimation, tels que définis par le fondateur de la psychanalyse.

Interspinous distraction in lumbar spinal stenosis: a neurophysiological perspective.

STUDY DESIGN: Prospective neurophysiological study. OBJECTIVE: To identify and quantify the neurophysiological effects of interspinous distraction during spine surgery for lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Interspinous devices have been introduced as an alternative treatment of LSS in selected patients aiming at obtaining indirect decompression. Nevertheless, there is no data on the immediate neurophysiological effect of distraction. METHODS: Thirty patients with LSS undergoing decompression (14 at single level, 16 at multiple levels) were enrolled, resulting in a total of 48 levels to be analyzed. Before decompression, calibrated incremental distraction simulating interspinous device implantation of 8, 10, 12, 14, and 16 mm was performed. Intraoperative motor evoked potentials were acquired before any distraction, during distraction at each incremental value and after bilateral decompression. We evaluated relative changes of motor evoked potentials normalized to hand muscles and related them to the number of affected levels, LSS radiological severity based on the A to D grading, lordosis, and disc height. RESULTS: For single-level disease, 8-mm distraction and open decompression yielded similar improvement in motor evoked potentials not only in levels with morphological grades A or B, but also in levels with morphological grades C or D (i.e., severe or extreme stenosis) (P = 0.32). In contrast, distraction superior to 8 mm was less effective (P ≤ 0.05). In multiple-level stenosis, decompression was significantly more effective than any degree of distraction (P < 0.001). No correlation of those results to disc height or lordosis was observed. Using χ trend test to analyze the effect of distraction, a linear trend favoring moderate over severe stenotic morphology was observed (P = 0.0349). CONCLUSION: Interspinous distraction of 8 mm is sufficient to replicate electrophysiological improvements obtained during full decompression even in severe single-level stenosis but not in multilevel disease. Interspinous distraction has therefore an immediately measurable neurophysiological effect. Level of Evidence: 4.

Evolution of gene expression in fire ants: the effects of developmental stage, caste, and species.

Ants provide remarkable examples of equivalent genotypes developing into divergent and discrete phenotypes. Diploid eggs can develop either into queens, which specialize in reproduction, or workers, which participate in cooperative tasks such as building the nest, collecting food, and rearing the young. In contrast, the differentiation between males and females generally depends upon whether eggs are fertilized, with fertilized (diploid) eggs giving rise to females and unfertilized (haploid) eggs giving rise to males. To obtain a comprehensive picture of the relative contributions of gender (sex), caste, developmental stage, and species divergence to gene expression evolution, we investigated gene expression patterns in pupal and adult queens, workers, and males of two species of fire ants, Solenopsis invicta and S. richteri. Microarray hybridizations revealed that variation in gene expression profiles is influenced more by developmental stage than by caste membership, sex, or species identity. The second major contributor to variation in gene expression was the combination of sex and caste. Although workers and queens share equivalent diploid nuclear genomes, they have highly distinctive patterns of gene expression in both the pupal and the adult stages, as might be expected given their extraordinary level of phenotypic differentiation. Overall, the difference in the proportion of differentially expressed genes was greater between workers and males than between workers and queens or queens and males, consistent with the fact that workers and males share neither gender nor reproductive capability. Moreover, between-species comparisons revealed that the greatest difference in gene expression patterns occurred in adult workers, a finding consistent with the fact that adult workers most directly experience the distinct external environments characterizing the different habitats occupied by the two species. Thus, much of the evolution of gene expression in ants may occur in the worker caste, despite the fact that these individuals are largely or completely sterile. Analyses of gene expression evolution revealed a combination of positive selection and relaxation of stabilizing selection as important factors driving the evolution of such genes.

A Small World Perspective on Urban Systems

The theory of small-world networks as initiated by Watts and Strogatz (1998) has drawn new insights in spatial analysis as well as systems theory. The theoryâeuro?s concepts and methods are particularly relevant to geography, where spatial interaction is mainstream and where interactions can be described and studied using large numbers of exchanges or similarity matrices. Networks are organized through direct links or by indirect paths, inducing topological proximities that simultaneously involve spatial, social, cultural or organizational dimensions. Network synergies build over similarities and are fed by complementarities between or inside cities, with the two effects potentially amplifying each other according to the âeurooepreferential attachmentâeuro hypothesis that has been explored in a number of different scientific fields (Barabási, Albert 1999; Barabási A-L 2002; Newman M, Watts D, Barabàsi A-L). In fact, according to Barabási and Albert (1999), the high level of hierarchy observed in âeurooescale-free networksâeuro results from âeurooepreferential attachmentâeuro, which characterizes the development of networks: new connections appear preferentially close to nodes that already have the largest number of connections because in this way, the improvement in the network accessibility of the new connection will likely be greater. However, at the same time, network regions gathering dense and numerous weak links (Granovetter, 1985) or network entities acting as bridges between several components (Burt 2005) offer a higher capacity for urban communities to benefit from opportunities and create future synergies. Several methodologies have been suggested to identify such denser and more coherent regions (also called communities or clusters) in terms of links (Watts, Strogatz 1998; Watts 1999; Barabási, Albert 1999; Barabási 2002; Auber 2003; Newman 2006). These communities not only possess a high level of dependency among their member entities but also show a low level of âeurooevulnerabilityâeuro, allowing for numerous redundancies (Burt 2000; Burt 2005). The SPANGEO project 2005âeuro"2008 (SPAtial Networks in GEOgraphy), gathering a team of geographers and computer scientists, has included empirical studies to survey concepts and measures developed in other related fields, such as physics, sociology and communication science. The relevancy and potential interpretation of weighted or non-weighted measures on edges and nodes were examined and analyzed at different scales (intra-urban, inter-urban or both). New classification and clustering schemes based on the relative local density of subgraphs were developed. The present article describes how these notions and methods contribute on a conceptual level, in terms of measures, delineations, explanatory analyses and visualization of geographical phenomena.

Antifungal drug resistance mechanisms in fungal pathogens from the perspective of transcriptional gene regulation.

Fungi are primitive eukaryotes and have adapted to a variety of niches during evolution. Some fungal species may interact with other life forms (plants, insects, mammals), but are considered as pathogens when they cause mild to severe diseases. Chemical control strategies have emerged with the development of several drugs with antifungal activity against pathogenic fungi. Antifungal agents have demonstrated their efficacy by improving patient health in medicine. However, fungi have counteracted antifungal agents in several cases by developing resistance mechanisms. These mechanisms rely on drug resistance genes including multidrug transporters and drug targets. Their regulation is crucial for the development of antifungal drug resistance and therefore transcriptional factors critical for their regulation are being characterized. Recent genome-wide studies have revealed complex regulatory circuits involving these genetic and transcriptional regulators. Here, we review the current understanding of the transcriptional regulation of drug resistance genes from several fungal pathogens including Candida and Aspergillus species.

Citizen participation and the Lisbon Treaty : A legal perspective

How to "bring the [European] Union closer to its citizens" is a vexed and vital problem of European integration. Article 11 TEU on participatory democracy, recently introduced by the Lisbon Treaty, is meant to be part of the solution. The EU Economic and Social Committee has gone so far as to define this provision "a milestone on the road to a people's Europe that is real and feasible". This appears to be an overly optimistic assessment - partly because art. 11 relies heavily on the involvement of civil society organisations, which political science literature suggests is conceptually and/or practically irrelevant to citizen involvement; partly because it largely formalizes participatory practices that have been in existence for years without cognizable effects on citizen participation; and partly because even its most innovative element - the European citizens' initiative (ECI) - does not bring significant changes to the Union's constitutional arrangements in terms of redistributing decision-making power. In addition to that, secondary legislation places significant hurdles on the submission of ECIs and might prevent or delay their becoming a standard democratic practice. This is not to say that art. 11 TEU has no potential at all. Its insertion in the Treaty might provide impetus to rethink and develop past participatory practices, such as horizontal civil dialogue. Moreover, the effects of "popular input" in the form of ECIs on EU institutional dynamics is as yet unknown - and perhaps not negligible, to judge from the keen interest that the European Parliament and other bodies have demonstrated in "appropriating" it as a political asset. Finally, art. 11 raises the stakes of the Union's democratic challenge and might pressure EU institutions to make full use of its potential. Or, if eventually proved inadequate, art. 11 might constitute a constitutional experiment on the way to meaningful forms of direct democracy at EU level.