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Atherosclerosis is characterized by a build-up of foam cells in the arterial wall, resulting from excess cholesterol uptake and accumulation of cytosolic lipid droplets (LDs). Autophagy has been shown to be atheroprotective in part by promoting the catabolism of LDs which liberates free cholesterol for efflux out of foam cells to cholesterol acceptors (ApoA-I or HDL) for removal from the body. Apart from macrophages (MΦ), vascular smooth muscle cells (VSMCs) comprise 50-70% of foam cells in the plaques. Unlike MΦ, the capacity of VSMC foam cells to metabolize cholesterol via autophagy is unknown. Here, we performed a comparative analysis of the autophagic capacity and cholesterol efflux of arterial foam cell subtypes of the atherosclerotic plaque. Atherosclerosis was induced in hypercholesterolemic autophagy reporter mice (GFP-LC3 mice receiving PCSK9-AAV and fed a Western diet). Autophagic flux in aortic digests was assessed by quantifying GFP-LC3 fluorescence after ex vivo treatment with the autophagy inhibitor Bafilomycin A1 or vehicle. MΦ foam cells displayed functional autophagy as shown by an accumulation of GFP-LC3 upon autophagy inhibition. In contrast, VSMC foam cells did not similarly accumulate GFP-LC3 upon bafilomycin treatment, suggesting dysfunction autophagy in these cells. Additionally, immunostaining of late-stage aortic roots showed MΦ, but not VSMC, foam cells induction of the active autophagy marker pATG16L1. Cell culture studies of lipid loaded MΦ and VSMC corroborated this inability for VSMCs to initiate autophagy in vivo . In vitro , MΦ foam cells effluxed cholesterol to ApoA-I (14%) and HDL (50%), whereas VSMC foam cells minimally effluxed cholesterol to HDL (7%) but not apoA-I. However, unlike MΦ foam cells, VSMC efflux was pharmacologically induced by treatment with metformin. Our data therefore demonstrates a lack of functional autophagy in VSMC, as compared to MΦ foam cells, which impairs their ability to perform cholesterol efflux. This autophagy defect in VSMC foam cells can be increased by autophagy activation using metformin, highlighting both the importance of understanding cholesterol metabolism in all foam cell populations and a new avenue to treat atherosclerosis.

Atherosclerosis is characterized by a build-up of foam cells in the arterial wall, resulting from excess cholesterol uptake and accumulation of cytosolic lipid droplets (LDs). Autophagy has been shown to be atheroprotective in part by promoting the catabolism of LDs which liberates free cholesterol for efflux out of foam cells to cholesterol acceptors (ApoA-I or HDL) for removal from the body. Apart from macrophages (MΦ), vascular smooth muscle cells (VSMCs) comprise 50-70% of foam cells in the plaques. Unlike MΦ, the capacity of VSMC foam cells to metabolize cholesterol via autophagy is unknown. Here, w e performed a comparative analysis of the autophagic capacity and cholesterol efflux of arterial foam cell subtypes of the atherosclerotic plaque . Atherosclerosis was induced in hypercholesterolemic autophagy reporter mice (GFP-LC3 mice receiving PCSK9-AAV and fed a Western diet). Autophagic flux in aortic digests was assessed by quantifying GFP-LC3 fluorescence after ex vivo treatment with the autophagy inhibitor Bafilomycin A1 or vehicle. MΦ foam cells displayed functional autophagy as shown by an accumulation of GFP-LC3 upon autophagy inhibition. In contrast, VSMC foam cells did not similarly accumulate GFP-LC3 upon bafilomycin treatment, suggesting dysfunction autophagy in these cells. Additionally, immunostaining of late-stage aortic roots showed MΦ, but not VSMC, foam cells induction of the active autophagy marker pATG16L1. Cell culture studies of lipid loaded MΦ and VSMC corroborated this inability for VSMCs to initiate autophagy in vivo . In vitro , MΦ foam cells effluxed cholesterol to ApoA-I (14%) and HDL (50%), whereas VSMC foam cells minimally effluxed cholesterol to HDL (7%) but not apoA-I. However, unlike MΦ foam cells, VSMC efflux was pharmacologically induced by treatment with metformin. Our data therefore demonstrates a lack of functional autophagy in VSMC, as compared to MΦ foam cells, which impairs their ability to perform cholesterol efflux. This autophagy defect in VSMC foam cells can be increased by autophagy activation using metformin, highlighting both the importance of understanding cholesterol metabolism in all foam cell populations and a new avenue to treat atherosclerosis.

Climate change is projected to increase fire severity and frequency in the boreal forest, but it could also directly affect post-fire recruitment processes by impacting seed production, germination, and seedling growth and survival. We reviewed current knowledge regarding the effects of high temperatures and water deficits on post-fire recruitment processes of four major tree species (Picea mariana, Pinus banksiana, Populus tremuloides and Betula papyrifera) in order to anticipate the effects of climate change on forest recovery following fire in the boreal biome. We also produced maps of future vulnerability of post-fire recruitment by combining tree distributions in Canada with projections of temperature, moisture index and fire regime for the 2041–2070 and 2071–2100 periods. Although our review reveals that information is lacking for some regeneration stages, it highlights the response variability to climate conditions between species. The recruitment process of black spruce is likely to be the most affected by rising temperatures and water deficits, but more tolerant species are also at risk of being impacted by projected climate conditions. Our maps suggest that in eastern Canada, tree species will be vulnerable mainly to projected increases in temperature, while forests will be affected mostly by droughts in western Canada. Conifer-dominated forests are at risk of becoming less productive than they currently are, and eventually, timber supplies from deciduous species-dominated forests could also decrease. Our vulnerability maps are useful for prioritizing areas where regeneration monitoring efforts and adaptive measures could be developed.

In the managed forest of Canada, forest fires are actively suppressed through efficient initial attack capability; however, the impact of different factors on the suppression success remains to be understood. The aim of this paper was to analyze the influence of operational suppression objectives (fire detection, initial attack, and fire control) along with fire intensity, fuel type, fire ignition cause, year, workload, and homogeneous fire regime zones on the achievement of the fire suppression objective (fire < 3 ha) using the Forest Fire Protection Agency of Quebec (SOPFEU) as a case study. The overall success of the suppression objective was very high (88%) over the study period (1994–2015). Both detection and control had significant effects on the suppression success through their interaction with fuel type, ignition cause, fire intensity, and zone variables. When the suppression objective was not achieved, final fire size was influenced by control, fuel type, fire intensity, and zone. The paper highlights the importance of the operational objectives and of regional differences for both fire suppression success and final fire size. Our results can help forest fire protection agencies to better understand their wildland fire suppression systems for a better adaptation to the upcoming fire regime changes. We gratefully acknowledge the Société de protection des forêts contre le feu (SOPFEU) and Mélanie Desrochers for providing the databases for the study. We thank Yan Boulanger and Steve Cumming for their constructive comments on an earlier version of this paper. The authors are thankful to Isabelle Lamarre for improving the quality of the English text. Research funding was provided by the New Forests European project to A. Cardil and by a postdoctoral research scholarship from the FRQNT (Fonds de recherche du Québec – Nature et technologies) to M. Lorente.

Canada's forests are shaped by disturbances such as fire, insect outbreaks, and droughts that often overlap in time and space. The resulting cumulative disturbance risks and potential impacts on forests are generally not well accounted for by models used to predict future impacts of disturbances on forest. This study aims at projecting future cumulative effects of four main natural disturbances, fire, mountain pine beetle, spruce budworm and drought, on timber volumes across Canada's forests using an approach that accounts for potential overlap among disturbances. Available predictive models for the four natural disturbances were used to project timber volumes at risk under aggressive climate forcing up to 2100. Projections applied to the current vegetation suggest increases of volumes at risk related to fire, mountain pine beetle, and drought over time in many regions of Canada, but a decrease of the volume at risk related to spruce budworm. When disturbance effects are accumulated, important changes in volumes at risk are projected to occur as early as 2011-2041, particularly in central and eastern Canada. In our last simulation period covering 2071-2100, nearly all timber volumes in most of Canada's forest regions could be at risk of being affected by at least one of the four natural disturbances considered in our analysis, a six-fold increase relative to the baseline period (1981-2010). Tree species particularly vulnerable to specific disturbances (e.g., trembling aspen to drought) could suffer disproportionate increases in their volume at risk with potential impacts on forest composition. By 2100, estimated wood volumes not considered to be at risk could be lower than current annual timber harvests in central and eastern Canada. Current level of harvesting could thus be difficult to maintain without the implementation of adaptation measures to cope with these disturbances.

Contexte : La notion d’« alliance pedagogique » a ete proposee comme cadre conceptuel de la retroaction axee sur le dialogue en supervision. Or, nous ne savons pas comment les superviseurs et les stagiaires en sciences de la sante se la representent et en font l’experience en supervision clinique. Objectifs : L’etude qualitative visait a decrire la signification de l’« alliance pedagogique » pour les superviseurs et les stagiaires en sciences de la sante, les facteurs contribuant ou non a son developpement, ainsi que les strategies de gestion des alliances pedagogiques plus difficiles qui furent vecues. Methodes : Des entrevues telephoniques semi-dirigees ont ete realisees aupres d’un echantillonnage intentionnel de 45 superviseurs et de 29 stagiaires en fin de programme provenant de medecine familiale, ergotherapie, orthophonie et physiotherapie de l’Universite Laval (Quebec, Canada). Les donnees transcrites sous forme de verbatim ont ete codifiees et ont fait l’objet d’une analyse thematique de contenu inductive. Resultats : La notion d’« alliance pedagogique » etait nouvelle pour la majorite des participants. Ses composantes sont la collaboration, la confiance, le respect et la communication. Lorsque celle-ci a ete vecue plus difficilement, les superviseurs et les stagiaires ont joue un role actif dans leur decision de discuter ouvertement ou non de la problematique en supervision, mais pour des raisons parfois differentes. Conclusion : L’alliance pedagogique est un processus interactionnel complexe qui est influence par plusieurs facteurs. Les resultats de cette etude serviront a mieux saisir sa signification et ses implications, ainsi qu’a elaborer des activites de formation, autant pour les superviseurs que pour les stagiaires.

The Eastern boreal forests of Quebec, Canada, have been extensively harvested over the past decades. Second-growth stands originating from sites harvested between 1920 and 1950 will soon reach the stage allowing for a second harvest. In order to guide the decision-makers responsible for ecosystem-based management of these forests, their specific management issues must be identified, based on the best knowledge available. In this context, we used the Delphi method and asked experts to identify and prioritize the main ecological issues related to the management of second-growth forests. Fourteen experts participated in at least one round of the process, out of an initial population of 30 known experts. After three rounds of questions, experts identified the maintenance of old-growth forests as the most important issue related to second-growth forest management in this region. The protection of woodland caribou and its habitat, and land fragmentation by forest roads were the second and third most important issues identified by the Delphi survey participants. These issues are not unique to second-growth forests, but should be given priority in considering management strategies associated with second-growth stands.

Wildfires, insect outbreaks, and windstorms are increasingly common forest disturbances.Post-disturbance management often involves salvage logging, i.e. the felling and removal of the affected trees. However, this practice may represent an additional disturbance witheffects on ecosystem processes and services. We developed a systematic map to provide an overview of the primary studies on this topic, and created a database with information on the characteristics of the retrieved publications, including information on stands, disturbance, intervention, measured outcomes, and study design. Of 4341 retrieved publications, 90 were retained in the systematic map. These publications represented 49 studies, predominantly from North America and Europe. Salvage logging after wildfire was addressed more frequently than after insect outbreaks or windstorms. Most studies addressed logging after a single disturbance event, and replication of salvaged stands rarely exceeded 10. The most frequent response variables were tree regeneration, ground cover, and deadwood characteristics., Junta de Andalucía, REMEDINAL

The frequency of forest fires is predicted to increase in Canada, which may affect the availability of timber for industrial purposes. We therefore carried out an evaluation of the timber supply vulnerability to current and future fire risk through simplified calculations involving historical forest growth and harvest rates and current and projected forest burn rates. Calculations were performed at the level of forest management areas (FMAs) across the boreal and montane ecozones of Canada. For some FMAs, the vulnerability of timber supply to fire was estimated to be high to extreme by the middle of the century. For those FMAs, the increases in tree growth necessary to negate these risks were generally unrealistic. A modest simulated decrease in tree growth over time, however, was sufficient to raise the vulnerability of many other FMAs from low to moderate. Known biases in the analysis suggest that our assessment might underestimate the level of vulnerability in all FMAs. Other natural disturbances are not included in the analysis but their impact on timber supply may be additive to that of fire. Some adaptation measures to face these increasing risks are discussed.

Forest management alters patterns generated by natural disturbances, particularly in ecosystems with infrequent fires. Management effects can differ according to spatial scale and affect ecological processes. To assess the effect of 80 years of forest management at both the landscape and burn/harvest scales on forest age, composition, density, spatial pattern and heterogeneity. Forest inventory maps and satellite images were used to compare two contiguous landscapes, respectively managed and unmanaged, of the eastern boreal forest of Canada, in a region with infrequent fires. Burns and harvests occurring from 1920–1950 were also compared. In addition to reducing the proportion of old-growth stands in the landscape, forest management changed forest composition at both scales, favouring the late-successional species balsam fir. Landscape metrics indicated that old-growth forests and spruce-dominated ones were more fragmented, less connected, and confined to smaller patches in the managed landscape than in the unmanaged one. Forest management increased heterogeneity at the landscape scale, but decreased it at the burn/harvest scale. Logging had a homogenizing effect at the burn/harvest scale by attenuating the effect of the physical environment on forest density. This study provides knowledge to help reduce effects of forest management at both scales. In this forest region with low fire recurrence, the goal should be to manage for greater forest heterogeneity at the burn/harvest scale whereas, at the landscape scale, restoration strategies should aim to create large contiguous patches of coniferous forests to increase spatial continuity as these were reduced by past management activities.

Interest in northern forests is increasing worldwide for both timber production and climate change mitigation. Studies exploring forest productivity at an early age after fire and its determining factors are greatly needed. We studied forest productivity, defined as the combined quality of stocking and growth, of 116 10- to 30-year-old postfire sites. The sites were spread over a 90 000 km2 area north of the Quebec commercial forestry limit and were dominated by Picea mariana (Mill.) B.S.P. and Pinus banksiana Lamb. Seventy-two percent of our sites were classified as unproductive, mainly because of poor growth. Because growth was mostly determined by climatic factors, afforestation alone may not be sufficient to increase stand productivity in our study area. In addition, our results suggest that P. banksiana on dry sites may be less resilient to fire than previously thought, presumably because of poor site quality and climate. Overall, this is one of the first studies to explore productivity issues at an early age in natural northern forests, and the analysis scheme that defines forest productivity as the result of growth and stocking could provide a useful tool to identify similar issues elsewhere.

Salvage logging following fire has become increasingly used during the last few decades as a way to mitigate economic losses caused by fire. The removal of burned mature trees including their aerial seedbanks immediately after fire could have impacts on post-fire tree recruitment but specific effects are still unknown. We conducted a study of a fire in the boreal forest of Quebec, Canada, to answer the following questions: Does fire severity influence tree compositional changes after fire? Does salvage logging affect these changes by favouring species that can reproduce vegetatively? Does salvage logging reduce among-sites heterogeneity relative to natural post-fire forests? To address these questions, we measured pre- and post-fire tree stocking (2 years after fire) of burned forest of different pre-fire stand composition types both in salvaged and non-salvaged sites, whereas fire severity was measured in the latter only. Species composition was evaluated using a Principal Component Analysis, and mixed models were used to test the effects of canopy fire severity, residual organic layer thickness, stand type and salvage logging on pre- to post-fire composition changes. In non-salvaged sites, fire severity had a significant effect on composition changes, and the effect depended on stand type. Low fire severity favoured species that can reproduce vegetatively such as Populus tremuloides , whereas moderate and high fire severity favoured the aerial seedbank species such as Pinus banksiana and Picea mariana . We found no effect of residual organic layer thickness on post-fire composition changes. Salvage treatment had a significant effect on post-fire composition changes and the effect depended on stand type. Overall, salvage logging tended to favour species relying upon vegetative reproduction more than fire alone, which favoured P. banksiana . Although among-site heterogeneity after salvage logging was not smaller than after fire only, salvage alters species composition more than does natural fire alone. Since salvage logging and low severity portions of the burn, which are generally not salvaged, both favour tree species with vegetative reproduction, our results suggest that these species will increase their dominance throughout the landscape if burned forests are systematically salvaged. We suggest strategies that can help to attenuate this divergence from natural post-fire conditions.

Neuronal migration disorders such as lissencephaly and subcortical band heterotopia are associated with epilepsy and intellectual disability. DCX, PAFAH1B1 and TUBA1A are mutated in these disorders; however, corresponding mouse mutants do not show heterotopic neurons in the neocortex. In contrast, spontaneously arisen HeCo mice display this phenotype, and our study revealed that misplaced apical progenitors contribute to heterotopia formation. While HeCo neurons migrated at the same speed as wild type, abnormally distributed dividing progenitors were found throughout the cortical wall from embryonic day 13. We identified Eml1, encoding a microtubule-associated protein, as the gene mutated in HeCo mice. Full-length transcripts were lacking as a result of a retrotransposon insertion in an intron. Eml1 knockdown mimicked the HeCo progenitor phenotype and reexpression rescued it. We further found EML1 to be mutated in ribbon-like heterotopia in humans. Our data link abnormal spindle orientations, ectopic progenitors and severe heterotopia in mouse and human., We thank the Inserm Avenir program, the French Agence National de la Recherche (ANR-08-MNP-013 (F.F.), ANR-13-BSV4-0008-01 (F.F.), ANR Blanc 1103-01 (J.C.), projet R11039KK, ANR E-Rare Program, convention 2011-RaARE-012-01) (J.C.), the Fondation Bettencourt Schueller and the Federation pour la recherche sur le cerveau (FRC) for grants awarded to F.F., the FRC Rotary for an equipment grant awarded to the Institut du Fer à Moulin, the Swiss National Science Foundation (SNSF 31003A-135574, SPUM-33CM30-124089 and 33CM30-140332) and the Fondation Gianni Biaggi de Blasys for grants awarded to A.C., and the SNSF (31003A-125379) for grants awarded to E.W. The research leading to a part of these results received funding from the European Union Seventh Framework Programme FP7/2007–2013 under the project DESIRE (grant agreement no. 602531), la Fondation pour la Recherche Médicale (FRM, J Chelly–Equipe FRM 2013: DEQ2000326477) la Fondation Jacques Espinasse & Danièle (JED)-Belgique and the Spanish Ministry of Economy and Competitiveness grant (BFU2012-33473) awarded to V.B.

Boreal mixedwood understory communities are highly dynamic because they are simultaneously influenced by canopy succession, small-scale environmental variation and disturbances. In such a system, fire initiates succession but canopy gaps, resulting from spruce budworm outbreaks or other disturbances, also affect forest dynamics during succession. In this study, we assessed the short-term response of understory communities along a canopy gap severity gradient in mature and old-growth forest stands. The objective was to determine if resource heterogeneity is driving understory community composition and diversity. We created artificial gaps of varying severities in stands of two late successional forest stages. Four treatments, i.e., total cut, conifer cut, girdling of conifers and a control treatment, were each applied over an area of 100 m2 and replicated three times in both types of forest stands. The cover of each understory species was measured before treatment application and 1, 2 and 11 years following it, in seven 1 m2 plots per replicate. Percent transmission of photosynthetic photon flux density and soil temperature were also measured on different occasions after the beginning of the experiment. Species richness, alpha diversity and total cover all increased following gap creation, and this increase was sustained up to 11 years. Increases were more pronounced in total cut than in other treatments. The increase in species richness and diversity was also more pronounced in old-growth stands, while total cover increase was greater in mature stands. Gap creation resulted in significant changes in abundance patterns that were associated with the resident species assemblages. The magnitude of changes in community composition did not significantly differ between mature and old-growth forests and differences in species composition among stands were maintained following gap creation. This study supports the evidence that resource heterogeneity resulting from small-scale disturbances will contribute to maintaining diversity among understory communities by allowing species more typical of early-successional communities to coexist with species from late-successional ones. Such a process may be essential for maintaining the species pool likely to re-invade the stands following major disturbances.

Pour les femmes victimes de violence conjugale, le départ du foyer et le séjour dans une maison d'hébergement ne représentent que la première étape d'un long processus de changement qui est souvent ponctué de crises. Un groupe de soutien a été mis sur pied pour aider ces femmes à établir de nouveaux modes de relations qui les rendraient aptes à traverser avec succès cette période difficile de leur vie. En s'inspirant des principes d'affinité, de présence et de consolidation élaborés par Lifton (1976), les auteures de cet article soulignent la valeur de la réciprocité dans la relation thérapeutique et proposent des éléments de réflexion sur les points saillants d'une intervention auprès des femmes victimes de violence conjugale ayant fait un séjour dans un centre d'hébergement., For battered women, leaving the home and spending time in a shelter is only the first step of a long process of change that usually involves periodic crises. A support group has been set up to help these women establish new ways to relate with the outside world, ways that are meant to assist them in successfully going through this difficult phase of their lives. Based on Lifton's principles of affinity, presence and consolidation (1976), the authors highlight the value of reciprocity in the therapeutical relationship. In addition, the authors discuss issues relating to the main points affecting interventions with battered women who have spent time in a shelter.

The influence of stand age and site conditions on the structure of coniferous stands was studied in the boreal forest of Quebec's Cote-Nord, a region with low fire recurrence. Stand diameter diversity was measured in 2202 forest inventory plots in black spruce (Picea mariana), balsam fir (Abies balsamea), and mixed stands using the Shannon-Wiener diversity index. A relative productivity index was developed based on the relationship between height and age of dominant trees. A stepwise regression analysis indicated that this productivity index best explains stand structure variation in all composition types, while stand age seems to influence structure more at the beginning of stand development. The results suggest that productive stands become uneven-sized earlier than unproductive stands and also maintain a greater diameter diversity. These contrasting structural dynamics may be explained by (i) a higher growth rate in richer stands that likely induces earlier senescence and thus an earlier passa...

Forest stand structure is an important element for biodiversity and, from a sustainable forest management perspective, uneven-sized stands should be managed in order to maintain the structural diversity over the landscape. The first objective of this study is to develop a statistical tool to characterize stand structure that can be used in forest management planning. The second objective is to classify the stand structure of two regions to illustrate a possible use for the tool. The statistical tool for characterizing stand structure has been developed from forest inventory data gathered by the ministère des Ressources naturelles du Québec, using discriminant analysis. The analysis makes it possible to classify the stands into three types of structure, even-sized, uneven-sized and inverse J-shaped, with an error rate estimated at only 7%. Proportions of different structure types in Quebec’s eastern black spruce forest region have been compared with those found in the western black spruce forest region. Nearly 90% of the western black spruce forest region is composed of pure black spruce stands, contrary to the eastern black spruce region, where there are more pure fir and mixed spruce-fir stands. Most of the western black spruce forest stands are even-sized (62%), while almost 70% of the eastern black spruce forest stands are uneven-sized or inverse J-shaped. Pure black spruce stands are more even-sized than pure fir stands, but regional differences are also found within pure black spruce stands. Our results show that it is possible to develop a robust tool that makes it possible to classify thousands of stands rapidly. Such tools are required if we want to consider stand structure for appropriate management prescriptions in the boreal forest. Key words: Even- and uneven-sized structure, fire regime, Picea mariana, Abies balsamea, boreal forest, structural diversity

The performance of the white pine weevil (Pissodes strobi Peck) was studied on five different host species: Norway spruce (Picea abies (L.) Karst.), white spruce (Picea glauca (Moench) Voss), red spruce (Picea rubens Sarg.), jack pine (Pinus banksiana Lamb.), and eastern white pine (Pinus strobus L.). Attacked terminal leaders were collected prior to adult emergence, within two different ecological regions of Quebec, the Outaouais and Appalaches regions. According to their natural range, jack pine was studied only in the Outaouais region and red spruce only in the Appalaches one. Weevil performance did not differ between regions but differed among host species. The number of eggs laid per leader was greatest on jack pine, white pine, and Norway spruce (279, 219, and 218 eggs per leader, respectively). Adults emerging from white pine were the heaviest (0.0104 g). The number of adults per leader was greater on Norway spruce and white pine (34 and 23 adults, respectively), and survival tended to be greater on Norway spruce and white spruce leaders (18 and 15%, respectively). Norway spruce had the longest leaders, and jack pine had the thickest ones. Leader dimensions were correlated with all variables of weevil performance, except insect survival, but these characteristics explain only a small part of the variation in weevil performance. Norway spruce and white pine can be considered favourable hosts for rapid population buildup according to the high number of emerging adults per attacked leader.

Interaction of rat kinesin and Drosophila nonclaret disjunctional motor domains with tubulin was studied by a blot overlay assay. Either plus-end or minus-end-directed motor domain binds at the same extent to both alpha- and beta-tubulin subunits, suggesting that kinesin binding is an intrinsic property of each tubulin subunit and that motor directionality cannot be related to a preferential interaction with a given tubulin subunit. Binding features of dimeric versus monomeric rat kinesin heads suggest that dimerization could drive conformational changes to enhance binding to tubulin. Competition experiments have indicated that kinesin interacts with tubulin at a Tau-independent binding site. Complementary experiments have shown that kinesin does not interact with the same efficiency with the different tubulin isoforms. Masking the polyglutamyl chains with a specific monoclonal antibody leads to a complete inhibition of kinesin binding. These results are consistent with a model in which polyglutamylation of tubulin regulates kinesin binding through progressive conformational changes of the whole carboxyl-terminal domain of tubulin as a function of the polyglutamyl chain length, thus modulating the affinity of tubulin for kinesin and Tau as well. These results indicate that microtubules, through tubulin polymorphism, do have the ability to control microtubule-associated protein binding.

The multiple functions of microtubules are mediated by various structural and motor microtubule-associated proteins (MAPs). To harmonize these functions in different places of a single cell, the key problem is to regulate the interactions of these proteins with microtubules. The chemical diversity of tubulin isoforms, which constitute the microtubule wall, could represent a molecular basis for this control. Using an in vitro assay of ligand blotting, we found that the microtubule-associated protein Tau interacts differentially with the diverse posttranslationally-modified isotubulins: its binding is mainly restricted to moderately-modified alpha- and beta-tubulin isoforms. We obtained evidence that the recently-discovered polyglutamylation, which consists of the sequential, posttranslational addition of one to six glutamyl units to both alpha- and beta-tubulin subunits, regulates the binding of Tau as a function of its chain length. The relative affinity of Tau, very low for unmodified tubulin, increases progressively for isotubulins carrying from one to three glutamyl units, reaches an optimal value, and then decreases progressively when the polygutamyl chain lengthens up to six residues. Our results suggest that the unmodified C-terminus of tubulin exerts a constitutive inhibition on Tau binding, probably by locking the MAP-binding site, and that this inhibition could be first released and then restored as the polyglutamyl chain grows. As the posttranslational chain does not appear to interact directly with Tau, it is thought that the growth of this chain from one to six glutamyl units causes a progressive, conformational shift in the structure of the C-terminal domain of tubulin, thus leading to the observed modulation of affinity.

If treating pensions, particularly occupational pensions, calls attention to social actors such as employers’ organizations and trade unions, we must also consider the role of operators of health insurance whose business is the management and development of the supplementary social welfare. However, many of these operators are a priori not merchants. Their goals are not profit and payment of shareholders. They are, for some, jointly managed social organizations created by social partners, for others, mutual and cooperative structures. Ipse would like to mention three approaches.

Question: In the boreal forest of eastern Canada, how does forest vegetation change in the sustained absence of fire? Location: Eastern boreal forest in Quebec's North Shore region, Canada (49°30′–50°00′N; 67°30′–68°35′W). Methods: Aerial photos from three different periods (1930, 1965 and 1987) were used to characterize changes in vegetation composition in 23 scenes of 200 ha. Time since fire, presence of secondary disturbances and data on soil and topographic variables were obtained. Ordination and clustering techniques were used to define compositional trajectories of change over the 57-yr period. These trajectories were further grouped into pathways based on compositional changes, time since fire and preferential deposit-drainage types. Results: Among the 26 compositional trajectories, three successional pathways were distinguished. Two start post-fire succession with a dominance of intolerant hardwood. In one of these, this is followed by an increase in Abies balsamea, while in the second the importance of Picea mariana increases with time. In the third pathway P. mariana is an important component from the outset. In this pathway, we observed modest fluctuation in the relative dominance of P. mariana and A. balsamea and variation in stand structure. Conclusion: The boreal forest vegetation of Eastern Canada is diverse and dynamic even in the absence of fire, notably under the influence of partial disturbances. Such disturbances can be associated with changes in composition or stand structure. The development of management strategies aimed at maintaining stand diversity by emulating a broader variety of partial and secondary disturbances should be encouraged.

Restriction of phage growth occurred when phage JHJ-1 propagated in one member of the genus Saccharopolyspora (S. hirsuta, S. taberi, S. rectivirgula, or the erythromycin-producing S. erythraea) was used to infect a different member. Of several S. erythraea strains tested, S. erythraea NRRL 2359 exhibited the weakest restriction. Phage SE-3 did not appear to be strongly restricted in Saccharopolyspora strains, whereas restriction of phages FRb-P and FRa-C was confined mainly to S. hirsuta NRRL B-5792. There was no correlation between the restriction of phage growth and the presence of exocytoplasmic DNAse. Key words: Saccharopolyspora, restriction, host range, bacteriophage JHJ-1, bacteriophage SE-3, bacteriophage FRa-C, bacteriophage FRb-P.

The distribution of a nuclear antigen ofPleurodeles waltl oocytes, recognized by the monoclonal antibody B24/1, has been studied during oogenesis and early embryonic development. In stage I oocytes the antigen was localized in the nucleoplasm and on two atypical structures of lampbrush chromosomes, the spheres (S) and the mass (M). The immunostaining increased as the oocyte developed. In stage VI oocytes, the nucleoplasm and spheres showed intense staining. At this stage, the nucleoplasm often contained free spheres which were also labelled. The staining of M diminished during oogenesis, as did its size. Immunoblots of nuclear proteins of oocytes at different stages confirmed that there was an accumulation of this protein during oogenesis. During embryonic development, the nuclei of all the cells of blastula and gastrula were labelled by this antibody: there was no embryonic regionalization. Starting from the neurula stage, the staining progressively disappeared from the nuclei of ectodermal and mesodermal cells. In the tailbud stage, only the endodermal cell nuclei showed faint staining. Immunoblots of proteins from embryos of different stages showed that the quantity of this protein was constant until the young gastrula stage and then decreased progressively; in the young tailbud stage, this protein was practically absent. B24/1 is the first described protein of the sphere. This protein is accumulated in the oocyte nucleus and behaves like a maternal polypeptide, shifting early in the nuclei during embryonic development. Thus, B24/1 probably has a function required from the early developmental stages, perhaps in relation with small nuclear ribonucleoproteins.

The Suppressor of fused (Su(fu)) protein is known to be a negative regulator of Hedgehog (Hh) signal transduction in Drosophila imaginal discs and embryonic development. It is antagonized by the kinase Fused (Fu) since Su(fu) null mutations fully suppress the lack of Fu kinase activity. In this study, we overexpressed the Su(fu) gene in imaginal discs and observed opposing effects depending on the position of the cells, namely a repression of Hh target genes in cells receiving Hh and their ectopic expression in cells not receiving Hh. These effects were all enhanced in a fu mutant context and were suppressed by cubitus interruptus (Ci) overexpression. We also show that the Su(fu) protein is poly-phosphorylated during embryonic development and these phosphorylation events are altered in fu mutants. This study thus reveals an unexpected role for Su(fu) as an activator of Hh target gene expression in absence of Hh signal. Both negative and positive roles of Su(fu) are antagonized by Fused. Based on these results, we propose a model in which Su(fu) protein levels and isoforms are crucial for the modulation of the different Ci states that control Hh target gene expression.

Polyglutamylation of tubulin has been implicated in several functions of microtubules, but the identification of the responsible enzyme(s) has been challenging. We found that the neuronal tubulin polyglutamylase is a protein complex containing a tubulin tyrosine ligase–like (TTLL) protein, TTLL1. TTLL1 is a member of a large family of proteins with a TTL homology domain, whose members could catalyze ligations of diverse amino acids to tubulins or other substrates. In the model protist Tetrahymena thermophila , two conserved types of polyglutamylases were characterized that differ in substrate preference and subcellular localization.

Sufu (Suppressor of fused) is a negative regulator of the Hedgehog signal-transduction pathway, interacting directly with the Gli family of transcription factors. However, its function remains poorly understood. In the present study, we determined the expression, tissue distribution and biochemical properties of mSufu (mouse Sufu) protein. We identified several mSufu variants of which some were phosphorylated. A yeast two-hybrid screen with mSufu as bait allowed us to identify several nuclear proteins as potential partners of mSufu. Most of these partners, such as SAP18 (Sin3-associated polypeptide 18), pCIP (p300/CBP-cointegrator protein) and PIAS1 (protein inhibitor of activated signal transduction and activators of transcription 1), are involved in either repression or activation of transcription and two of them, Galectin3 and hnRNPA1 (heterogeneous nuclear ribonucleoprotein A1), have a nuclear function in pre-mRNA splicing. We confirmed the mSufu–SAP18 and mSufu–Galectin3 interactions by independent biochemical assays. Using a cell transfection assay, we also demonstrated that mSufu protein (484 amino acids) is predominantly cytoplasmic but becomes mostly nuclear when a putative nuclear export signal is mutated or after treatment of the cells with leptomycin B. Moreover, mSufu is translocated to the nucleus when co-expressed with SAP18, which is normally found in this compartment. In contrast, Galectin3 is translocated to the cytoplasm when it is co-expressed with mSufu. Our findings indicate that mSufu is a shuttle protein that appears to be extremely versatile in its ability to bind different proteins in both the cytoplasm and nucleus.

Polyglutamylation is a post-translational modification initially discovered on tubulin. It has been implicated in multiple microtubule functions, including neuronal differentiation, axonemal beating and stability of the centrioles, and shown to modulate the interaction between tubulin and microtubule associated proteins. The enzymes catalysing this modification are not yet known. Starting with a partially purified fraction of mouse brain tubulin polyglutamylase, monoclonal antibodies were raised and used to further purify the enzyme by immunoprecipitation. The purified enzyme complex (Mr 360×103) displayed at least three major polypeptides of 32, 50 and 80×103, present in stochiometric amounts. We show that the 32×103 subunit is encoded by the mouse gene GTRGEO22, the mutation of which has recently been implicated in multiple defects in mice, including male sterility. We demonstrate that this subunit, called PGs1, has no catalytic activity on its own, but is implicated in the localisation of the enzyme at major sites of polyglutamylation, i.e. neurones, axonemes and centrioles.

Type I lissencephaly is a cortical malformation disorder characterized by disorganized cortical layers and gyral abnormalities and associated with severe cognitive impairment and epilepsy. The exact pathophysiological mechanisms underlying the epilepsy and mental retardation in this and related disorders remain unknown. Two genes, LIS1 and doublecortin, have both been shown to be mutated in a large proportion of cases of type I lissencephaly and a milder allelic disorder, subcortical laminar heterotopia (SCLH). Studying the protein products of these genes and the biochemical pathways in which they belong is likely to yield important information concerning both normal and abnormal cortical development. The relationships between the LIS1 and Doublecortin proteins are not yet well defined, but both are believed to play a critical role in cortical neuronal migration. Lis1 is expressed from very early development in the mouse and in both proliferating cells and post-mitotic neurons of the cortex. This protein is likely to have multiple functions since it is a subunit of the enzyme platelet-activating factor acetylhydrolase, which degrades platelet activating factor, and has also been shown to be involved in microtubule dynamics, potentially influencing nuclear migration through its interaction with the dynein motor protein complex. Doublecortin on the other hand is exclusively expressed in post-mitotic neurons and is developmentally regulated. In young developing neurons Doublecortin has a specific subcellular localization at the ends of neuritic and leading processes. This localization, combined with our previous data showing that it is a microtubule-associated protein and that it interacts with adapter complexes involved in vesicle trafficking, suggests a role in the growth of neuronal processes, downstream of directional or guidance signals. The observations summarized here favor the suggestion that whereas LIS1 may play a role in nuclear migration, Doublecortin is instead restricted to functions at the leading edge of the cell.

Recently, we and others reported that the doublecortin gene is responsible for X-linked lissencephaly and subcortical laminar heterotopia. Here, we show that Doublecortin is expressed in the brain throughout the period of corticogenesis in migrating and differentiating neurons. Immunohistochemical studies show its localization in the soma and leading processes of tangentially migrating neurons, and a strong axonal labeling is observed in differentiating neurons. In cultured neurons, Doublecortin expression is highest in the distal parts of developing processes. We demonstrate by sedimentation and microscopy studies that Doublecortin is associated with microtubules (MTs) and postulate that it is a novel MAP. Our data suggest that the cortical dysgeneses associated with the loss of Doublecortin function might result from abnormal cytoskeletal dynamics in neuronal cell development.

For large programs, static analysis can be one of the most time-consuming phases of the whole compilation process. We propose a new paradigm for the implementation of static analyses that is inspired by partial evaluation techniques. Our paradigm does not reduce the complexity of these analyses, but it allows an efficient implementation. We illustrate this paradigm by its application to the problem of control flow analysis of functional programs. We show that the analysis can be sped up by a factor of 2 over the usual abstract interpretation method.

Tau microtubule-associated proteins constitute a group of developmentally regulated neuronal proteins. Using the high-resolution two-dimensional polyacrylamide gel electrophoresis system, we have resolved more than 60 distinct Tau isoforms in the adult mouse brain. Tau protein heterogeneity increases drastically during the second week of brain development. In neuronal primary cell cultures, some of these developmental changes can be observed. The increase of Tau heterogeneity in culture is more limited and reaches a plateau after a period corresponding to the second week of development. Most, if not all, of the vast Tau heterogeneity can be attributed to intensive post-translational phosphorylation, which may affect the structure of the proteins.

Fibronectin (FN) synthesis during oogenesis and early embryogenesis of the amphibian Pleurodeles waltlii was investigated. The isotopically labelled amino acids [3H]leucine and [35S]methionine were incubated with oocytes or microinjected into embryos. Newly synthesized FN was analysed by polyacrylamide gel electrophoresis, using the high resolution two-dimensional gel system described by O'Farrell. With this method and fluorography we demonstrate that FN synthesis begins during oogenesis. De novo synthesized FN appears during cleavage and gastrulation. Using actinomycin D we show the presence of maternal messenger RNA coding for FN. It is translated during the cleavage and gastrulation stages.

Germinal vesicles of oocytes from Pleurodeles waltlii were used for immunization of BALB/c mice to obtain hybridomas secreting monoclonal antibodies. The hybridomas were screened for reactivity of their antibodies against lampbrush chromosomes of oocytes, as revealed by indirect immunostaining. Antibodies labelling the lampbrush chromosomes were also tested on histological sections of oocytes, embryos, and larvae of Pleurodeles. Characterization of the antigens was accomplished through immunoblotting of two-dimensional electrophoretic gels of germinal vesicle proteins. The ten monoclonal antibodies giving a positive reaction were classed into five groups. Group 1, exemplified by antibody A33, recognizes all the lampbrush chromosome transcribing sites (loops). Moreover, it differentially labels the cell nuclei during embryonic and larval development. Group 2, antibody B71, also stains all the loops of the lampbrush chromosomes, but does not react with cell nuclei of embryos and larvae. Group 3, antibody A1, labels specific loops, some of which are heterozygous in the strain of P. waltlii used. These heterozygosities have allowed us to localize and to characterize a chromosomal segment on bivalent IV which is heteromorphic in the two partners of the bivalent. We suggest that this heteromorphism represents a morphological distinction between Z and W heterochromosomes. Moreover, this antibody reacts with only one transcription unit along a loop that contains several units. Group 4, antibody B24, stains the only two structures in the lampbrush chromosomes of P. waltlii that do not have a loop organization, the mass "M" and the spheres. Group 5, antibody A35, reacts with the chromomeres. The antigens corresponding to antibodies A33 and B24 have been identified as proteins, which have apparent molecular weights of 80 and 104 kilodaltons, respectively. They correspond to proteins abundant in the germinal vesicles. All the antibodies described here cross-react with the lampbrush chromosomes of five other species of Urodeles.

The distribution of 2 nuclear antigens in the interphase nuclei of liver of Pleurodeles waltl was determined with the help of monoclonal antibodies, using immunofluorescence for light microscopy and indirect immunoperoxidase and immunogold labeling procedures for electron microscopic localization. The antibodies C36/1 and A33/22 label antigens with relative molecular masses of 270 kDa and 80 kDa, and isoelectric points of 7.0 and 6.4, respectively. The liver of urodels is characterized by the presence of a peripheral layer of hematopoietic cells around the parenchymatous tissue formed by typical hepatocytes. The antibody C36/1 labels the nuclei of both types of cells, whereas the antibody A33/22 labels the nuclei of hepatocytes but not those of the peripheral hematopoietic cells. With both these antibodies, labeling, whenever observed, is restricted to fibrillar structures in the interchromatin space, i.e., to peri- and inter-chromatin fibrils; condensed chromatin, nucleoli, and nuclear envelope are not labeled.