Biologie

Iron chlorosis is an important nutritional disease that affects orchards and vineyards reducing quality and yield production. In soil, high calcareous conditions affect pH, raising it to sub-alkaline and alkaline levels and maintaining iron in an insoluble form as Fe 3+ . Chlorotic plants show abnormal photosynthesis and yellowing shoots. Nowadays the most used protection against iron chlorosis is grafting the cultivars of economic interest on tolerant rootstocks. Genetic improvement of fruit trees plays an important role on the selection of iron chlorosis resistant rootstocks using breeding techniques. In grapevine, this selection is based on breeding cultivars belonging to the V. vinifera species with non-vinifera ones (i.e., wild American species). In grapevine, iron uptake and homeostasis are controlled by a mechanism known as "Strategy I", characteristic of non-graminaceous plants and based on a system of iron reduction, soil acidification and transporters-mediated uptake. In this study, main Strategy I-genes involved in iron uptake were identified and analysed in two grapevine rootstocks characterized by different levels of tolerance and susceptibility to iron chlorosis. Expression analyses on selected genes under different iron-availability conditions revealed important differences which could explain the different degree of tolerance observed in the two genotypes under study.

Résu m é : Lors de l'exploitation de sources sucrées de grande taille, M. sabuleti pratique une récolte collective basée sur l'utilisation d'un recrutem ent de m asse. Au niveau global, l'exploitation de deux sources de saccharose est, en général, de type asym étrique : l'activité de la colonie se concentre sur une des deux sources, l'autre étant sous-exploitée. Le com portem ent collectif de M. sabuleti présente néanm oins une certaine flexibilité : si une source 0,5M est découverte avant une source IM, les colonies restent prisonièrcs de leur premier choix; par contre, si une source 0,1M est découverte avant une source IM, les sociétés déplacent rapidem ent leur activité vers la source riche. L'interprétation de nos résultats fait appel à un modèle mathématique sim ple capable de simuler les situations de choix testées. Par ailleurs, nos résultats sont comparés à ceux obtenus sur deux autres espèces étudiées dans des conditions expérim entales comparables. Mots-clés : For micidae, My r mica sabuleti, r ec r utement alimentai r e, décisions collectives, modélisation mathématique. Summary : From food re cruitme nt to colle ctive décisions : tiie case of My r mica sabuleti. When exploiting large sugar sources, the colonies of M. sabuleti use mass recruitment. At the Society level, the exploitation of 2 sources of sucrose is generally asymmetrical : the activity of the colony concentrâtes on one source, the other being underexploited. Nevertheless, the collective behaviour of M. sabuleti shows a certain degree of flexibility : if a 0,5M source is discovered before a IM source, the colonies stay with their first choice. By contrast, if a 0,1M source is discovered before a IM source, the societies rapidly shift their activity towards the richer source. The interprétation of our results is based upon a sim ple m athem atical m odel which sim ulâtes the tested choice situations. In addition, our results are com pared to others obtained using two other species studied under comparable expérimental conditions.

Without Tiemory the optimal net benefit is given when the food sources are eoual in size to the ants' carrying capacity and smaller ants are more efficient t!^an larger ants in poorer environments. With memory smaller ants are more efficient with small food-sources and larger ants with very large Poodsources. Under certain intermediary conditions being the riqht size is more important than having a memory and under others the reverse is true.

Commu n lcative efficien cy can bs evaluated in terms of the veloclty at which in formation is tran smitted Ce.g. recruitmen t rate), or in terms of the accuracy of commun ication Ce.g. dispersion aroun d the target}. Although the recruitmen t rates are usually con sidered when comparin g food recruitmen t methods in an ts (e.g. Chadab an d Retten meyer 1975), accuracy has been n early completely n eglected. It is well kn own , however, that an imal behavior is probabilistic, in particular an t commun ication [Wilson , 1962), an d that accordin gly, on ly a fraction of recruited an ts will actually reach the food source, "lost" an ts explorin g the en viron men t. We will présent h ère expérimental évidence sh owing th at th e amount of "noise" during food recruitment communication varies con siderably between species, and th at "lost" ants, exploring th e environment, can discover new food sources and initiate new recruit ment with possible advantages for th e society. It is almost a truism to consider th at wh en only one food source is présent, th e most efficient recruitment is th e most accurate. However, we will deinonstrate with th e h elp of a math ema tical model, th at a certain amount of noise is needed in order to minimize food collection time wh en a multiple source situation is encountered, and wh en th e sources sh ow some degree of aggregation.

Collective behavior based on self-organization has been shown in group-living animals from insects to vertebrates. These findings have stimulated engineers to investigate approaches for the coordination of autonomous multirobot systems based on self-organization. In this experimental study, we show collective decision-making by mixed groups of cockroaches and socially integrated autonomous robots, leading to shared shelter selection. Individuals, natural or artificial, are perceived as equivalent, and the collective decision emerges from nonlinear feedbacks based on local interactions. Even when in the minority, robots can modulate the collective decision-making process and produce a global pattern not observed in their absence. These results demonstrate the possibility of using intelligent autonomous devices to study and control self-organized behavioral patterns in group-living animals.

In ants, aggregation is mainly based on the attraction between individuals. We confirmed the existence of ground marking in Lasius niger and demonstrated its influence on the aggregative behaviour of ants: the place of the gathering is leading by the existence of a ground marking which favours clustering by increasing the rate of the process but does not change the aggregation level. This factor could play a role in the choice of a new nest site and in the spatial distribution of ants inside the nest. This marking, presuming to have a long duration, could represent an external memory which could play an important role in various situations such as the choice of new nest or the reorganisation of ants after a disturbance.

Genetic variations in the four casein genes CSN1S1, CSN2, CSN1S2, and CSN3 have obtained substantial attention since they affect the milk protein yield, milk composition, cheese processing properties, and digestibility as well as tolerance in human nutrition. Furthermore, milk protein variants are used for breed characterization, biodiversity, and phylogenetic studies. The current study aimed at the identification of casein protein variants in five domestic goat breeds from Sudan (Nubian, Desert, Nilotic, Taggar, and Saanen) and three wild goat species [Capra aegagrus aegagrus (Bezoar ibex), Capra nubiana (Nubian ibex), and Capra ibex (Alpine ibex)]. High-density capture sequencing of 33 goats identified in total 22 non-synonymous and 13 synonymous single nucleotide polymorphisms (SNPs), of which nine non-synonymous and seven synonymous SNPs are new. In the CSN1S1 gene, the new non-synonymous SNP ss7213522403 segregated in Alpine ibex. In the CSN2 gene, the new non-synonymous SNPs s...

Supplement to chapter 1 An Overview of Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications (H. Scheer) All formulas in chapter 1 have been generated with the freeware program "C-Design" (J. Bauer, E. Fontain), which is available under: Sample formulas and schemes prepared with "C-Design" (ending .cdw) can be downloaded from this page. They require C-Design for opening and editing. A non-editable compilation in AdobeWriter format (.pdf) can be downloaded here. Major chlorophylls, with phytol and farnesol Chlorophylls a and b (IUPAC numbered) Chlorin-type chlorophylls and several esterifying alcohols Bacteriochlorophyll a (IUPAC numbered) Metallo bacteriochlorophyllls Protochlorophyllide a Chlorophyll enols (partial structures) Chlorophyll Biosynthesis: Overview From protoporphyrin IX to phlorophylls Porphobilinogen cyclization to protoporphyrin Chlorophyll nomenclature Fischer (left) vs. IUPAC numbering (right) Numbering, ß-ligand, and spectroscopic axes Others Major tetrapyrrole formulas Z-scheme of photosynthesis

Short-term assays have suggested that RNA interference (RNAi) may be a powerful new method for intracellular immunization against human immunodeficiency virus type 1 (HIV-1) infection. However, RNAi has not yet been shown to protect cells against HIV-1 in long-term virus replication assays. We stably introduced vectors expressing small interfering RNAs (siRNAs) directed against the HIV-1 genome into human T cells by retroviral transduction. We report here that an siRNA directed against the viral Nef gene (siRNA-Nef) confers resistance to HIV-1 replication. This block in replication is not absolute, and HIV-1 escape variants that were no longer inhibited by siRNA-Nef appeared after several weeks of culture. These RNAi-resistant viruses contained nucleotide substitutions or deletions in the Nef gene that modified or deleted the siRNA-Nef target sequence. These results demonstrate that efficient inhibition of HIV-1 replication through RNAi is possible in stably transduced cells. Therefore, RNAi could become a realistic gene therapy approach with which to overcome the devastating effect of HIV-1 on the immune system. However, as is known for antiviral drug therapy against HIV-1, antiviral approaches involving RNAi should be used in a combined fashion to prevent the emergence of resistant viruses.

The non-conventional yeastPichia pastoris(syn.Komagataella phaffii) has become a powerful eukaryotic expression platform for biopharmaceutical and biotechnological applications on both laboratory and industrial scales. Despite the fundamental role that artificial transcription factors (ATFs) play in the orthogonal control of gene expression in synthetic biology, a limited number of ATFs are available forP. pastoris. To establish orthogonal regulators for use inP. pastoris, we characterized ATFs derived from Arabidopsis TFs. The plant-derived ATFs contain the binding domain of TFs from the plantArabidopsis thaliana, in combination with the activation domains of yeastGAL4and plantEDLLand a synthetic promoter harboring the cognatecis-regulatory motifs. Chromosomally integrated ATFs and their binding sites (ATF/BSs) resulted in a wide spectrum of inducible transcriptional outputs inP. pastoris, ranging from as low as 1- to as high as ∼63-fold induction with only small growth defects. We...

The commitment of Reuber H 35 hepatoma cells to DNA synthesis was studied by exposing cells which were synchronized by serum depletion, to serum. It is shown that the period of commitment is 6-8 hr, independent of the length of the.Gl phase. It can even occur during the G2 period of the previous cell cycle.

Background High-throughput technologies have opened new avenues to study biological processes and pathways. The interpretation of the immense amount of data sets generated nowadays needs to be facilitated in order to enable biologists to identify complex gene networks and functional pathways. To cope with this task multiple computer-based programs have been developed. GeneTrail is a freely available online tool that screens comparative transcriptomic data for differentially regulated functional categories and biological pathways extracted from common data bases like KEGG, Gene Ontology (GO), TRANSPATH and TRANSFAC. Additionally, GeneTrail offers a feature that allows screening of individually defined biological categories that are relevant for the respective research topic. Results We have set up GeneTrail for the use of Arabidopsis thaliana. To test the functionality of this tool for plant analysis, we generated transcriptome data of root and leaf responses to Fe deficiency and the...

The recurrence of influenza A epidemics has originally been explained by a ''continuous antigenic drift'' scenario. Recently, it has been shown that if genetic drift is gradual, the evolution of influenza A main antigen, the haemagglutinin, is punctuated. As a consequence, it has been suggested that influenza A dynamics at the population level should be approximated by a serial SIR model. Here, simple models are used to test whether a serial SIR model requires gradual antigenic drift within groups of strains with the same antigenic properties (antigenic clusters). We compare the effect of status based and history based frameworks and the influence of reduced susceptibility and infectivity assumptions on the transient dynamics of antigenic clusters. Our results reveal that the replacement of a resident antigenic cluster by a mutant cluster, as observed in data, is reproduced only by the status based model integrating the reduced infectivity assumption. This combination of assumptions is useful to overcome the otherwise extremely high model dimensionality of models incorporating many strains, but relies on a biological hypothesis not obviously satisfied. Our findings finally suggest the dynamical importance of gradual antigenic drift even in the presence of punctuated immune escape. A more regular renewal of susceptible pool than the one implemented in a serial SIR model should be part of a minimal theory for influenza at the population level.

Question: How do species traits and abiotic factors influence the extent of hydrochorous dispersal into and out of a small floodplain area along a freeflowing river in The Netherlands? Location: The Kappersbult nature reserve (53107 0 28 00 N, 6137 0 14 00 E), which is a floodplain along the Dutch River Drentsche Aa. Methods: Seeds transported by the river were collected in fine mesh nets for 24 consecutive hours once or twice a week for 1 year, upstream and downstream of the studied floodplain. Data on the captured seeds were related to species traits and abiotic factors and species composition in the floodplain. The floodplain functioned both as a seed source and sink. High levels of river water seemed to promote seed transport to or from the floodplain. Seeds of riverbank species occurred significantly more often in the river water than expected. Net source species had significantly higher seed production, taller stature and higher seed buoyancy, but lower site elevation than net sink species. Seed weight was significantly higher for sink species than for other species. Our study found that inundation, and therefore more natural river water management, is a prerequisite for seed transport to and from a floodplain. The restoration of target floodplain vegetation may be successful for common species that produce many seeds and grow in proximity to the river. Consequently, it is expected that the probability of restoring vegetation types that occur further from the river, such as wet grasslands, by hydrochorous dispersal is low.

Genetic variations in the four casein genes CSN1S1, CSN2, CSN1S2, and CSN3 have obtained substantial attention since they affect the milk protein yield, milk composition, cheese processing properties, and digestibility as well as tolerance in human nutrition. Furthermore, milk protein variants are used for breed characterization, biodiversity, and phylogenetic studies. The current study aimed at the identification of casein protein variants in five domestic goat breeds from Sudan (Nubian, Desert, Nilotic, Taggar, and Saanen) and three wild goat species [Capra aegagrus aegagrus (Bezoar ibex), Capra nubiana (Nubian ibex), and Capra ibex (Alpine ibex)]. High-density capture sequencing of 33 goats identified in total 22 non-synonymous and 13 synonymous single nucleotide polymorphisms (SNPs), of which nine non-synonymous and seven synonymous SNPs are new. In the CSN1S1 gene, the new non-synonymous SNP ss7213522403 segregated in Alpine ibex. In the CSN2 gene, the new non-synonymous SNPs s...

Although mangroves dominated by Avicennia germinans and Rhizophora mangle are extending over 6000 ha in the Tanbi Wetland National Park (TWNP) (The Gambia), their importance for local populations (both periurban and urban) is not well documented. For the first time, this study evaluates the different mangrove resources in and around Banjul (i.e., timber, non-timber, edible, and ethnomedicinal products) and their utilization patterns, including the possibility of ecotourism development. The questionnaire-based results have indicated that more than 80% of peri-urban population rely on mangroves for timber and non-timber products and consider them as very important for their livelihoods. However, at the same time, urban households demonstrate limited knowledge on mangrove species and their ecological/economic benefits. Among others, fishing (including the oyster-Crassostrea cf. gasar collection) and tourism are the major incomegenerating activities found in the TWNP. The age-old practices of agriculture in some parts of the TWNP are due to scarcity of land available for agriculture, increased family size, and alternative sources of income. The recent focus on ecotourism (i.e., boardwalk construction inside the mangroves near Banjul city) received a positive response from the local stakeholders (i.e., users, government, and non-government organizations), with their appropriate roles in sharing the revenue, rights, and responsibilities of this project. Though the guidelines for conservation and management of the TWNP seem to be compatible, the harmony between local people and sustainable resource utilization should be ascertained.

National audienceCes milieux aquatiques fournissent de nombreux services écosystémiques, en assurant des fonctions de support (production primaire, biodiversité), de régulation(épuration des nutriments, régulation des flux hydriques), d’approvisionnement (eau potable, irrigation, énergie) et socio-culturels (loisir, tourisme). Souvent perçusà tort comme immuables, stables et en dehors de toute pression, les plans d’eau font l’objet de multiples usages anthropiques, impactant leur fonctionnement. Lechangement climatique en cours ne fait qu’exacerber ces impacts et accélérer la dégradation des milieux ; à l’échelle régionale, ses effets restent encore à évaluer. Dans cet ouvrage, nous avons souhaité illustrer, de la manière la plus large possible, la variété des systèmes lentiques présents en Nouvelle-Aquitaine,ainsi que les lacunes de connaissance que diverses études mettent en évidence. Le but de cet ouvrage est d’apporter des éclairages scientifiques pourl’aide à la décision et aux...

Major histocompatibility (MHC) molecules are encoded by extremely polymorphic genes and play a crucial role in vertebrate immunity. Natural selection favors MHC heterozygous hosts because individuals heterozygous at the MHC can present a larger diversity of peptides from infectious pathogens than homozygous individuals. Whether or not heterozygote advantage is sufficient to account for a high degree of polymorphism is controversial, however. Using mathematical models we studied the degree of MHC polymorphism arising when heterozygote advantage is the only selection pressure. We argue that existing models are misleading in that the fitness of heterozygotes is not related to the MHC alleles they harbor. To correct for this, we have developed novel models in which the genotypic fitness of a host directly reflects the fitness contributions of its MHC alleles. The mathematical analysis suggests that a high degree of polymorphism can only be accounted for if the different MHC alleles confer unrealistically similar fitnesses. This conclusion was confirmed by stochastic simulations, including mutation, genetic drift, and a finite population size. Heterozygote advantage on its own is insufficient to explain the high population diversity of the MHC.

Macrophage plasticity is critical for controlling inflammation including those produced by helminth infections, where alternatively activated macrophages (AAM) are accumulated in tissues. AAM expressing the co-inhibitory molecule programmed death ligand 2 (PD-L2), which is capable of binding programmed death 1 (PD-1) expressed on activated T cells, have been demonstrated in different parasitic infections. However, the role of PD-L2 during F. hepatica infection has not yet been explored. We observed that F. hepatica infection or a F. hepatica total extract (TE) injection increased the expression of PD-L2 on peritoneal macrophages. In addition, the absence of PD-L2 expression correlated with an increase in susceptibility to F. hepatica infection, as evidenced by the shorter survival and increased liver damage observed in PD-L2 deficient (KO) mice. We assessed the contribution of the PD-L2 pathway to Th2 polarization during this infection, and found that the absence of PD-L2 caused a diminished Th2 type cytokine production by TE stimulated splenocytes from PD-L2 KO infected compared with WT mice. Besides, splenocytes and intrahepatic leukocytes from infected PD-L2 KO mice showed higher levels of IFN-γ than those from WT mice. Arginase expression and activity and IL-10 production were reduced in macrophages from PD-L2 KO mice compared to those from WT mice, revealing a strong correlation between PD-L2 expression and AAM polarization. Taken together, our data indicate that PD-L2 expression in macrophages is critical for AAM induction and the maintenance of an optimal balance between the Th1-and Th2-type immune responses to assure host survival during F. hepatica infection.

How could bios and psyche emerge from physical-chemical ? Is "emergence" an answer to this question or just an embarrassment? This article offers a fundamentally new perspective.

Wie konnte aus dem Physikalisch-Chemischen Bios und aus diesem wiederum Psyche entstehen? Ist "Emergenz" darauf eine Antwort oder nur eine Verlegenheit?  Eine grundlegend neue Sicht bietet dieser Beitrag.

Bis 1992 als Klärschlammdeponie genutzte Teiche in Bramsche-Achmer haben sich für viele Wat- und Wasservogelarten zwischenzeitlich zu einem bedeutenden Lebensraum entwickelt. In dem ca. 3 ha großen Gebiet brüteten 1993-1995 mehrere Arten der "Roten-Liste". Für Rastvögel besitzt das Gebiet lokale bis regionale (= landesweite) Bedeutung. Die Situation der Feuchtgebietsarten in der mitteleuropäischen Kulturlandschaft und die Bedeutung von künstlichen Feuchtgebieten als Trittsteinbiotope wird diskutiert. Gestaltungsvorschläge werden unterbreitet.Sewage plants - a tertiary habitat for nature. A small area of approx. 3 ha near Bramsche, Lower Saxony, formerly used as asewage plant, is still of importance for many waders and waterfowl. Some highly endangered species bred there between 1993-1995, e.g. Teal Anas crecca, Spotted Crake Porzana porzana. The site was also of local and regional importance for many migrating species. The situation of wetlands and the role of artifical we...

Heterogeneous physiognomy and observed diversity of woody vegetation in savanna are considered as specific responses of seedling species during their growth to the given site characteristics changeable with time. Consequently, understanding early plant attitude using different growth soil is an important indicator in choosing species to introduce or to assist natural or artificial regeneration to the extent that establishment and productivity of plant species are not solely controlled by the effects of habitat modification and/or environmental resource availability but mostly by seedling quality. This study focused on comparative assessment of growth performance and adaptive traits of early seedlings of Balanites aegyptiaca, Diospyros mespiliformis and Tamarindus indica three multipurpose species between of Macrotermes subhyalinus mound and surrounding area in order to understand the attitudes of woody species hosted by termite mounds. Seedlings of similar age per species were grown in plastic bags as pots containing composite soils sampled till a depth of 30 cm on mounds and surrounding area in Tiogo state forest and of which the amount of retained water, carbon (C), nitrogen (N), calcium (Ca), magnesium (Mg), assimilable phosphorus (ass. P) and potassium (K) were quantified prior to growth experiment. Height and collar diameter of seedling stems, final length and diameter of the main root were measured; the total dry biomass of root and shoot and, root to shoot ratio were evaluated for seedlings up to 5 months relating to the soil origin. Mean values of retained water and selected nutrients were higher for mound soil than for surrounding soil. Besides, the studied parameters of T. indica seedlings were significantly higher for mound soil than those recorded for surrounding soil (P<0.05) whereas seedlings of B. aegyptiaca and D. mespiliformis exhibited an increase final stem collar diameter and main root length on mound soil (P=0.039 and 0.028 respectively). Root to shoot ratio of B. aegyptiaca seedlings was positively correlated with great N content and that of D. mespiliformis seedlings with great concentration of Ca. Growth performance and adaptive traits of early seedlings of B. aegyptiaca, D. mespiliformis and T. indica were remarkable on M. subhyalinus mound soil compared to surrounding soil relating to the great level of soil fertility. Therefore, understanding the attitude of woody seedlings of local or exotic species is an important key in global plantation programs or assisting natural regeneration for biodiversity management and conservation.

ZUSAMMENFASSUNG 1 INTRODUCTION 1.1 Epidemiology of colon cancer 1.2 Etiology of colon caner 1.3 Prognosis of colon caner 1.4 Colorectal liver metastasis 1.5 Therapeutic approaches for colorectal liver metastasis 1.6 Physiopathology of Liver Metastasis 1.6.1 The role of the host in metastasis 1.6.2 Specific growth or specific homing 1.7 Microarray technologies for global gene expression profiles and identification of invasion related genes 1.8 CXC chemokines 1.9 β-catenin 1.10 Aim of the thesis

The timber of the species Lophira alata (azobe) is very popular for outdoor constructions, which favours its overexploitation and illegal logging. We sampled individuals from Liberia, Ivory Coast, Ghana, Nigeria, Cameroon, Gabon, Congo Brazzaville and Republic Democratic of Congo to discover new nuclear and plastidial SNP and INDEL loci through restriction associated DNA sequencing (RADSeq) and low coverage MiSeq genome sequencing. From an initial set of 397 loci, a final set of 126 loci was selected for timber tracking purposes.

 RVP je dokument, který je závazný pro organizaci a obsah výuky různých profesí na různých školách  Víme-li, že máme 281 platných RVP SOV, pak si musíme položit otázky: 1) Jakým způsobem připravit studijní programy pro přípravu budoucích učitelů? 2) Lze vůbec nalézt průsečík alespoň pro některé skupiny podobných oblastí vzdělávání?

Van Driessche et al.: DNA cytosine methylation in the Bovine Leukemia Virus promoter is associated with latency in a Lymphoma-derived B-cell line : potential involvement of direct inhibition of CREB/CREM/ATF binding. Retrovirology 2011 8(Suppl 1):A27.

This paper examines the image used to promote tourism activities in mangroves and how those activities are actually managed and interact with mangroves in Caribbean islands. The study focused on Jamaica (Black River Lower Morass), Guadeloupe (Grand Cul-de-Sac Marin) and Martinique (Bay of Genipa). The communication (arguments and illustrations) used by the local travel agents to attract people in the mangroves were studied and local actors interviewed. Firstly, it was noticeable that communications used ecological characteristics for each studied area, transport modalities together with stereotypes about the "postcard picture" of the environment in the Caribbean. Despite their activities linked to mangrove ecosystems, 62% of operators directly proposed mangrove areas in their promotional literature and 38% used other arguments (sun, snorkeling, food & drinks, among others). Two kinds of illustrations were most used to attract visitors into mangrove areas. On the one hand these forests are displayed as mysterious natural and wild sites and on the other hand as a good place to practice leisure activities and to relax, enjoying the paradisiacal seascape. Secondly, we investigated the actual use of the mangrove by tourism. Mangroves are involved at three levels: physical, temporal and cultural. And for the commercial image which represents the mangrove, the requested resources and interest degree in activities are different. It was concluded that tourism in mangrove areas is presented as a "soft" form of ecotourism, a one day trip which combines the discovery of particular natural sceneries and relaxing activities.

Analyses of 55 individual and 31 concatenated protein data sets encoded in Reclinomonas americana and Marchantia polymorpha mitochondrial genomes revealed that current methods for constructing phylogenetic trees are insufficiently sensitive (or artifact-insensitive) to ascertain the sister of mitochondria among the current sample of eight aproteobacterial genomes using mitochondrially-encoded proteins. However, Rhodospirillum rubrum came as close to mitochondria as any a-proteobacterium investigated. This prompted a search for methods to directly compare eukaryotic genomes to their prokaryotic counterparts to investigate the origin of the mitochondrion and its host from the standpoint of nuclear genes. We examined pairwise amino acid sequence identity in comparisons of 6,214 nuclear protein-coding genes from Saccharomyces cerevisiae to 177,117 proteins encoded in sequenced genomes from 45 eubacteria and 15 archaebacteria. The results reveal that ;75% of yeast genes having homologues among the present prokaryotic sample share greater amino acid sequence identity to eubacterial than to archaebacterial homologues. At high stringency comparisons, only the eubacterial component of the yeast genome is detectable. Our findings indicate that at the levels of overall amino acid sequence identity and gene content, yeast shares a sister-group relationship with eubacteria, not with archaebacteria, in contrast to the current phylogenetic paradigm based on ribosomal RNA. Among eubacteria and archaebacteria, proteobacterial and methanogen genomes, respectively, shared more similarity with the yeast genome than other prokaryotic genomes surveyed.

Jasmonates (JAs) and salicylic acid (SA) are plant hormones that play pivotal roles in the regulation of induced defenses against microbial pathogens and insect herbivores. Their signaling pathways cross-communicate providing the plant with a regulatory potential to finely tune its defense response to the attacker(s) encountered. In Arabidopsis thaliana, SA strongly antagonizes the jasmonic acid (JA) signaling pathway, resulting in the downregulation of a large set of JA-responsive genes, including the marker genes PDF1.2 and VSP2. Induction of JA-responsive marker gene expression by different JA derivatives was equally sensitive to SA-mediated suppression. Activation of genes encoding key enzymes in the JA biosynthesis pathway, such as LOX2, AOS, AOC2, and OPR3 was also repressed by SA, suggesting that the JA biosynthesis pathway may be a target for SA-mediated antagonism. To test this, we made use of the mutant aos/dde2, which is completely blocked in its ability to produce JAs because of a mutation in the ALLENE OXIDE SYNTHASE gene. Mutant aos/dde2 plants did not express the JA-responsive marker genes PDF1.2 or VSP2 in response to infection with the necrotrophic fungus Alternaria brassicicola or the herbivorous insect Pieris rapae. Bypassing JA biosynthesis by exogenous application of methyl jasmonate (MeJA) rescued this JA-responsive phenotype in aos/dde2. Application of SA suppressed MeJA-induced PDF1.2 expression to the same level in the aos/dde2 mutant as in wild-type Col-0 plants, indicating that SA-mediated suppression of JAresponsive gene expression is targeted at a position downstream of the JA biosynthesis pathway.

The main objective of this study was to assess how mangrove reforestation has influenced litter degradation and concomitant nutrient dynamics in previously deforested plantations. Dynamics of nutrients (carbon, nitrogen and C:N ratios) in decomposing leaves of conspecific species were investigated with litterbags in Sonneratia alba and Rhizophora mucronata reforested treatments using appropriate bare and natural less disturbed treatments as controls. Bare treatments had the lowest decay rates (Kd À1 ) and thus the highest t 50 values (when 50% of the original weight had been decomposed) for both species. The contrary was true for natural treatments, while both parameters were intermediate in reforested treatments, suggesting that other than direct litter input, reforestation has modified site conditions which have enhanced organic matter decomposition. There were significant seasonal differences in decay rates for treatments within the R. mucronata species, with rates being higher during the wet season with accompanying lower t 50 values. Decay rates were overall higher (P < 0.05) in the S. alba species and as a result no litter was retrieved from its natural treatment by the 5th week. Higher amphipod colonisation was observed in reforested and natural treatments than bare treatments, which may have contributed to higher decay rates in the former. There were significant differences (P < 0.05) in N concentration among treatments with natural and reforested treatments having similarly higher concentrations than bare treatments in both seasons. C:N ratios (an important determinant of nutritional leaf quality) were also similarly low in natural and reforested treatments and higher in bare treatments. Mangrove reforestation thus seems to have enhanced litter degradation and concomitant nutrient remineralisation, suggesting that other than species litter quality, tidal inundation and seasonal factors, specific stand management regimes play an important role in determining the efficiency of these ecological processes in mangrove ecosystems.

L'objet de cette conférence est d'engager une réflexion sur le statut des langues naturelles et sur celui des conceptions, représentations et/ou modèles élaborés à propos de ces langues. Cette réflexion sera organisée en trois temps. Nous procéderons d'abord à un bref examen des positionnements philosophiques et épistémologiques qui sous-tendent et orientent notre conception du langage, dans ses rapports au monde et à l'activité humaine. Nous proposerons ensuite une analyse détaillée des propriétés de l'activité langagière et des systèmes de langues, qui s'inspire du cadre théorique de l'interactionisme socio-discursif que nous défendons. Sur cette base, nous développerons enfin une réflexion sur les différents niveaux de connaissance ou de "savoirs" qui sont élaborés à propos de la réalité langagière, qui débouchera sur une tentative de clarification de la position que les chercheurs en sciences du langage ou en didactique se devraient de prendre dans le débat entre la vie et l'évolution des langues d'une part, les règles, modèles et normes qui visent à stabiliser ces mêmes langues d'autre part.

Objectives: To evaluate the safety and efficacy of adding ciclosporin A (CSA) to the treatment of patients with psoriatic arthritis (PsA) demonstrating an incomplete response to methotrexate (MTX) monotherapy. Methods: In a 12 month, randomised, double blind, placebo controlled trial at five centres in three countries, 72 patients with active PsA with an incomplete response to MTX were randomised to receive either CSA (n = 38) or placebo (n = 34). Patients underwent full clinical and radiological assessment and, in addition, high resolution ultrasound (HRUS) was performed at one centre. An intention to treat (last observation carried forward) analysis was employed. Results: Some significant improvements were noted at 12 months in both groups. However, in the active but not the placebo arm there were significant improvements in swollen joint count, mean (SD), from 11.7 (9.7) to 6.7 (6.5) (p,0.001) and C reactive protein, from 17.4 (14.5) to 12.7 (14.3) mg/l (p,0.05) as compared with baseline. The Psoriasis Area and Severity Index (PASI) score improved in the active group (2 (2.3) to 0.8 (1.3)) as compared with placebo (2.2 (2.7) to 1.9 (2.8)), p,0.001, and synovitis detected by HRUS (33 patients, 285 joints) was reduced by 33% in the active group compared with 6% in the placebo group (p,0.05). No improvement in Health Assessment Questionnaire or pain scores was detected. Conclusions: Synovitis detected by HRUS was significantly reduced. Combining CSA and MTX treatment in patients with active PsA, and a partial response to MTX, significantly improves the signs of inflammation but not pain or quality of life.

Objective: To determine whether, as predicted by predator-prey dynamics, early withdrawal of antiretroviral therapy, i.e., when the number of CD4+ lymphocytes is still elevated, results in an overshoot of HIV-1 viraemia due to infection of increased numbers of available target cells at that time. Design and methods: Five HIV-1-infected individuals were identified who discontinued antiretroviral therapy for various reasons after 8-19 days, and from whom stored serum samples obtained before, during, and shortly after treatment were available for measurement of HIV-1 RNA load. A mathematical model was designed to assess whether increased target cell availability could quantitatively explain the clinical observations. Results: After therapy withdrawal, increases in the HIV-1 RNA load to levels exceeding pretreatment values by log 10 0.6-1.5 copies/ml were observed after 2-17 days in all four of the individuals who had treatment-induced increases in CD4+ cell counts at the time of therapy withdrawal. Increases in viraemia were maximal within a few days, and subsequently seemed to wane until the pretreatment equilibrium between virus and its target cells was attained. Mathematical modelling confirms that these transient increases in viraemia can be explained by increased availability of target cells at the time of therapy withdrawal. Transient rises in HIV-1 viraemia do occur following early therapy withdrawal. These rises especially warrant consideration in short-term antiretroviral regimens for prevention of mother-to-child transmission, as are being studied in developing countries, since they could result in an increased transmission risk during the post-partum period through breast-feeding. This possibility needs to be investigated urgently.

L’investigation scientifique repose sur un certain nombre de propositions (axiomes, postulats, hypothèses) qui ne sont presque jamais elles-mêmes l’objet de quelconques réflexions ou recherches. Or, il s’avère que ces énoncés, notamment lorsqu’ils sont mis en relation les uns avec les autres, révèlent un certain nombre de contradictions et de paradoxes qui suggèrent, pour le moins, diverses interrogations. Cet aspect est particulièrement prégnant au sein des sciences biologiques, et tout spécifiquement la théorie darwinienne de l’évolution par sélection naturelle – théorie pourtant largement acceptée par la communauté scientifique internationale, et considérée comme définitivement "prouvée". Ces contradictions et paradoxes, qui fragilisent grandement la biologie et le darwinisme, tout en étant pour l’essentiel ignorés, relèvent de ce que j’appelle une véritable "schizophrénie" intellectuelle – une "schizophrénie darwiniste". Dans cette première partie, je m’attacherai à montrer l’importance tant quantitative que qualitative de cette profonde problématique, insistant notamment sur les aspects historiques ayant graduellement mené à une désintégration des sciences du vivant ; j’insisterai, à plusieurs reprises, sur des solutions possibles pour la redéfinition d’une biologie authentique, fondée, par exemple, sur des préceptes lamarckiens et recentrée sur son sujet premier : l’individu biologique.

The ability of activated Ras to induce growth arrest of human ovarian surface epithelial (HOSE) cells via induction of the cyclin-dependent kinase inhibitor p21 WAF1/CIP1 has been used to screen for Ras pathway signaling components using a library of RNA interference (RNAi) vectors targeting the kinome. Two known Ras-regulated kinases were identified, phosphoinositide 3-kinase p110a and ribosomal protein S6 kinase p70 S6K1 , plus the MAP kinase kinase kinase kinase MINK, which had not previously been implicated in Ras signaling. MINK is activated after Ras induction via a mechanism involving reactive oxygen species and mediates stimulation of the stress-activated protein kinase p38 MAPK downstream of the Raf/ERK pathway. p38 MAPK activation is essential for Rasinduced p21 WAF1/CIP1 upregulation and cell cycle arrest. MINK is thus a distal target of Ras signaling in the induction of a growth-arrested, senescent-like phenotype that may act to oppose oncogenic transformation in HOSE cells.

Sandy sediments of continental shelves and most beaches are often thought of as geochemical deserts because they are usually poor in organic matter and other reactive substances. The present study focuses on analyses of dissolved biogenic compounds of surface seawater and pore waters of Aquitanian coastal beach sediments. To quantitatively assess the biogeochemical reactions, we collected pore waters at low tide on tidal cross-shore transects unaffected by freshwater inputs. We recorded temperature, salinity, oxygen saturation state, and nutrient concentrations. These parameters were compared to the values recorded in the seawater entering the interstitial environment during floods. Cross-shore topography and position of piezometric level at low tide were obtained from kinematics GPS records. Residence time of pore waters was estimated by a tracer approach, using dissolved silica concentration and kinetics estimate of quartz dissolution with seawater. Kinetics parameters were based on dissolved silica concentration monitoring during 20-day incubations of sediment with seawater. We found that seawater that entered the sediment during flood tides remained up to seven tidal cycles within the interstitial environment. Oxygen saturation of seawater was close to 100%, whereas it was as low as 80% in pore waters. Concentrations of dissolved nutrients were higher in pore waters than in seawater. These results suggest that aerobic respiration occurred in the sands. We propose that mineralised organic matter originated from planktonic material that infiltrated the sediment with water during flood tides. Therefore, the sandy tidal sediment of the Aquitanian coast is a biogeochemical reactor that promotes or accelerates remineralisation of coastal pelagic primary production. Mass balance calculations suggest that this single process supplies about 37 kmol of nitrate and 1.9 kmol of dissolved inorganic phosphorus (DIP) to the 250-km long Aquitanian coast during each semi-diurnal tidal cycle. It represents about 1.5% of nitrate and 5% of DIP supplied by the nearest estuary.

Spiral waves in a small disk and on a small sphere 63-64 Davydov, V.A. and Zykov, V.S. 65-67 filamentous fungi Deutsch, Α., Dress, A. and Rensing, L. Dupont, G. and Goldbeter, A. Dutt, A.K. Chemical pattern formation: An overview 75-77 Epstein, I.R. Pattern formation in the oscillatory regime of the CO-oxidation 78-81 on Pt(110) Falcke, M. and Engel, Η. Period doublings, period three, chaos, and quasiperiodicity in 82-84 the peroxidase -oxidase reaction: Experimental and theoretical studies Geest, Τ., Larter, R., Steinmetz, C. and Olsen, L.F. A cellular automaton model of excitable media 85-88 Gerhardt, Μ. Developmental complexity and evolutionary order 89 Goodwin, B. Theorist's view of a beautiful experiment: how many states of 90-92 Rayleigh-B£nard turbulence? Grossmann, S. and Lohse, D.

Background: Surgery is a curative treatment for patients with locally advanced colon cancer, but recurrences are frequent for those with stage III disease. FOLFOX adjuvant chemotherapy has been shown to improve recurrence-free survival and overall survival by more than 20% and is nowadays considered a standard of care. However, the vast majority of patients will not benefit from receiving cytotoxic drugs because they have either already been cured by surgery or because their tumor cells are resistant to the chemotherapy, for which predictive factors are still not available. Identifying which patients are unlikely to respond to adjuvant chemotherapy from among those who are eligible for such treatment would be a major step towards treatment personalization. It would spare such patients from unnecessary toxicities and would improve the allocation of societal healthcare resources. Methods/design: PePiTA is a prospective, multicenter, non-randomised trial built on the hypothesis that preoperative chemosensitivity testing using FDG-PET/CT before and after one course of FOLFOX can identify the patients who are unlikely to benefit from 6 months of adjuvant FOLFOX treatment for stage III colon cancer. The study's primary objective is to examine the ability of PET/CT-assessed tumor FDG uptake after one course of preoperative chemotherapy to predict the outcome of adjuvant therapy, as measured by 3-year disease-free survival. Secondary objectives are to examine the predictive value of changes in PET/CT-assessed tumor FDG uptake on overall survival, to define the best cut-off value of FDG uptake for predicting treatment outcome, and to analyse the cost-effectiveness of such preoperative chemo-sensitivity testing. At study planning, exploratory translational research objectives were 1) to assess the predictive value of circulating tumor cells for disease-free survival, 2) to examine the predictive value of single nucleotide polymorphisms for disease-free survival with respect to genes related either to toxicity or to drug targets, 3) to assess genomic rearrangements associated with response or resistance to FOLFOX treatment, 4) to identify an immunologic signature associated with metabolic tumor response to FOLFOX therapy and, finally, 5) to create a bank of frozen tumor samples for future studies.