Mostrando recursos 141 - 160 de 506

  1. Genetic sub-structure and intermediate optimal outcrossing distance in the marine angiosperm Zostera marina

    Billingham, M. R.; Simões, T.; Reusch, T. B. H.; Serrão, Ester
    The spatial distribution of genetic variability depends on the spatial patterns of clonal and sexual reproduction, gene flow, genetic drift and natural selection. Species with restricted dispersal may exhibit genetic structuring within populations with immediate neighbours being close relatives, and may show differentiation among populations. Genetic structuring of a species may have important genetic, evolutionary and ecological consequences including distance-dependent mating success. In this study we used microsatellite markers to show that clones of Zostera marina in a population in the Ria Formosa, Portugal, were aggregated and covered distances of up to 3–4 m. Clones within 4 m of each...

  2. The evolution of Cicada songs contrasted with the relationships inferred from mitochondrial DNA (Insecta, hemiptera)

    Fonseca, P. J.; Serrão, Ester; Pina-Martins, F.; Silva, P.; Mira, S.; Quartau, J. A.; Paulo, O. S.; Cancela, Leonor
    The molecular phylogeny of nine Palaearctic species of cicadas (Hemiptera, Cicadoidea) was inferred using two mitochondrial DNA genes, Cytochrome Oxidase I and II. The two main groups detected, namely species within Tettigetta and Tympanistalna, as well as the two species investigated in the genus Cicada, are robustly supported across the analytical methods. The structure of the song syllables, generated during single tymbal cycles of males of the analysed group of species is remarkably consistent in these two phyletic lines. This reflects the morphology and the mechanics of the tymbal. However the higher level song patterns, which depend on the activity...

  3. Periodicity of propagule expulsion and settlement in the competing native and invasive brown seaweeds, Cystoseira humilis and Sargassum muticum (Phaeophyta)

    Engelen, A. H.; Espirito-Santo, C.; Simões, T.; Monteiro, C. A.; Serrão, Ester; Pearson, G. A.; Santos, Rui
    Dense stands of the invasive species Sargassum muticum (Yendo) Fensholt develop in tidal pools close to its southern distributional limit in Europe, the southwest coast of Portugal. Along this coast, sheltered tidal pools form a specific habitat in which colonization occurs. Invaded pools are originally inhabited by Cystoseira humilis Kützing. Differences in gamete release between the competing native and alien species might be important for the initial settlement and further spread of the invader. Therefore, we tested whether egg expulsion and embryo settlement in both species had the same timing with respect to lunar and tidal cycles. For more than...

  4. Genetic differentiation and secondary contact zone in the seagrass Cymodocea nodosa across the Mediterranean-Atlantic transition region

    Alberto, F.; Massa, S. I.; Manent, P.; Diaz-Almela, E.; Arnaud-Haond, S.; Duarte, C. M.; Serrão, Ester
    Aim  A central question in evolutionary ecology is the nature of environmental barriers that can limit gene flow and induce population genetic divergence, a first step towards speciation. Here we study the geographical barrier constituted by the transition zone between the Atlantic Ocean and the Mediterranean Sea, using as our model Cymodocea nodosa, a seagrass distributed throughout the Mediterranean and in the Atlantic, from central Portugal to Mauritania. We also test predictions about the genetic footprints of Pleistocene glaciations. Location  The Atlantic–Mediterranean transition region and adjacent areas in the Atlantic (Mauritania to south-west Portugal) and the Mediterranean. Methods  We used eight microsatellite...

  5. Purification and functional reconstitution of the human CHIP28 water channel expressed in Saccharomyces cerevisiae

    Laizé, Vincent; Ripoche, P.; Tacnet, F.
    The yeast Saccharomyces cerevisiae was used for these proteins are of primary importance to appreciate heterologous expression of the human CHIP28 water their physiological role in living organisms. Aquaporin-1 channel (Aquaporin-1). A nine-amino- Recently, CHIP28 was expressed functionally in acid epitope of the influenza hemagglutinin protein yeast secretory vesicles in our laboratory (3). This work (HA epitope), recognized by the monoclonal antibody indicated that wild-type or mutant aquaporins could 12CA5, was chosen to tag CHIP28 at its N-terminus. be produced easily in this new heterologous expression Epitope-tagged CHIP28 was purified from yeast ex- system for functional analyses. Such studies are fretracts...

  6. Molecular and functional study of AQY1 from Saccharomyces cerevisiae: role of the C-terminal domain

    Laizé, Vincent; Gobin, R.; Rousselet, G.; Badier, C.; Hohmann, S.; Ripoche, P.; Tacnet, F.
    The yeast YPR192w gene, which encodes a protein (Aqy1p) with strong homology to aquaporins (AQPs), was cloned from nine S. cerevisiae strains. The osmotic water permeability coefficient (Pf) of X. laevis oocytes expressing the gene cloned from the S1278b strain (AQY1-1) was 5.7 times higher than the Pf of oocytes expressing the gene cloned from other strains (AQY1-2). Aqy1-1p, initially cloned without its C-terminus (Aqy1-1DCp), mediated an ;3 times higher water permeability than the full-length protein. This corresponds to a 3-fold higher protein density in the oocyte plasma membrane, as shown by freeze-fracture electron microscopy. Pf measurements in yeast spheroplasts confirmed...

  7. Polymorphism of Saccharomyces cerevisiae aquaporins

    Laizé, Vincent; Tacnet, F.; Ripoche, P.; Hohmann, S.
    Aquaporin water channels facilitate the transmembrane diffusion of water and higher organisms possess a large number of isoforms. The genome of the yeast Saccharomyce cerevisiae contains two highly similar aquaporin genes, AQY1 and AQY2. AQY1 has been shown to encode a functional water channel but only in certain laboratory strains. Here we show that the AQY2 gene is interrupted by an 11 bp deletion in 23 of the 27 laboratory strains tested, with the exception of strains from the S1278b background, which also exhibit a functional Aqy1p. However, although the AQY2 gene from S1278b is highly homologous to functional aquaporins, we...

  8. Detection of mineralized structures in very early stages of development of Marine Teleostei using a modified Alcian blue-Alizarin red double staining technique for bone and cartilage

    Gavaia, Paulo J.; Sarasquete, C.; Cancela, Leonor
    We have developed a procedure for staining cartilage and bone in fish larvae as small as 2 mm (notochord length), for which standard alcian blue/alizarin red procedures did not give positive and/or consistent results. Small calcified structures only 100-200 pm in length can be clearly visualized. The method is suitable for both ontogenic studies during early stages of skeletal development in most marine fishes (e.g., Sparus aurata L., Solea senegalensis Kaup), whose larvae at hatching are often only a few millimeters long and for detecting skeletal abnormalities in small larvae. This procedure can also be used for specimens that have been preserved in...

  9. Co-feeding in Senegalese sole larvae with inert diet from mouth opening promotes growth at weaning

    Engrola, S.; Figueira, L.; Conceição, L. E. C.; Gavaia, Paulo J.; Ribeiro, L.; Dinis, Maria Teresa
    The aim of this study was to determine if sole larvae co-fed with inert diet at mouth opening would perform better than larvae fed with live prey and if such a feeding regime would produce better quality juveniles. The experiment was separated in to two phases: pelagic and benthic. In the pelagic phase, treatments consisted of the standard feeding regime (rotifer and Artemia feeding), the standard feeding regime and inert diet, and rotifer for a longer period than the standard feeding regime until larvae reached 9 days after hatching (DAH). By the end of the pelagic phase, when the postlarvae were 20...

  10. ESSA1 embryonic stem like cells from gilthead seabream: a new tool to study mesenchymal cell lineage differentiation in fish

    Parameswaran, V.; Laizé, Vincent; Gavaia, Paulo J.; Cancela, Leonor
    Embryonic stem (ES) cells are a promising tool for generation of transgenic animals and an ideal experimental model for in vitro studies of embryonic cell development, differentiation and gene manipulation. Here we report the development and initial characterization of a pluripotent embryonic stem like cell line, designated as ESSA1, derived from blastula stage embryos of the gilthead seabream (Sparus aurata, L). ESSA1 cells are cultured in Leibovitz’s L-15 medium supplemented with 5% fetal bovine serum and, unlike other ES cells, without a feeder layer. They have a round or polygonal morphology, grow exponentially in culture and form dense colonies. ESSA1 cells also...

  11. Effect of egg incubation temperature on the occurrence of skeletal deformities in Solea senegalensis

    Dionísio, G.; Campos, C.; Valente, L. M. P.; Conceição, L. E. C.; Cancela, Leonor; Gavaia, Paulo J.
    Temperature is a factor known to have a marked influence on metabolism and consequently on development, inducing ontogenetic plasticity in fish larvae. In this study, three different temperatures (15, 18 and 21 C) were assayed during Solea senegalensis embryonic development prior to hatching. After hatching all larvae were reared at the same temperature (21.0 ± 0.1 C) until 30 days. We observed that lowering the incubation temperature from 21 to 15 C reduced the incidence of skeletal deformities from 80 to 60%. Intermediate incubation temperature (18 C), resulted in larvae that displayed a rate of abnormalities close to that observed at 15...

  12. Zebrafish as a model to study craniofacial phenotypes related to human MEF2Cmutations

    Adriao, A.; Conceição, N.; Gavaia, Paulo J.; Cancela, Leonor
    Background: MEF2C is a transcription factor with important roles in differentiation and developmental processes, in particular in endochondral bone development. An association between human MEF2C gene mutations and particular phenotypes affecting craniofacial formation has been shown. Recent studies have shown that the zebrafish palate is under a genetic control similar to that controlling amniotic palatal skeleton, demonstrating the utility of this organism to study craniofacial development. Zebrafish has two mef2c genes and different lines of mutants are available. Therefore we have used zebrafish in an attempt to correlate specific MEF2C mutations with the abnormal human craniofacial phenotypes.

  13. Solea senegalensis vasa transcripts: molecular characterisation, tissue distribution and developmental expression profiles

    Pacchiarini, T.; Cross, I.; Leite, Ricardo B.; Gavaia, Paulo J.; Ortiz-Delgado, J. B.; Pousão-Ferreira, P.; Rebordinos, L.; Sarasquete, C.; Cabrita, E.
    The Vasa protein is an RNA helicase belonging the DEAD (Asp-Glu-Ala-Asp)-box family. The crucial role played by the vasa gene in the germ-cell lineage of both vertebrates and invertebrates has made this gene a useful molecular marker for germinal cells and a useful tool in surrogate broodstock production using primordial germ cell transplantation. With the aim of establishing a novel approach to improving Solea senegalensis broodstock management, the vasa gene in this species was characterised. Four S. senegalensis vasa transcripts were isolated: Ssvasa1, Ssvasa2, Ssvasa3 and Ssvasa4. Their phylogenetic relationship with other vasa homologues was determined confirming the high degree of conservation...

  14. Skeletal anomalies in reared European fish larvae and juveniles. Part 2: main typologies, occurrences and causative factors

    Boglione, C.; Gisbert, Enric; Gavaia, Paulo J.; Witten, Paul; Moren, Mori; Fontagné, Stéphanie; Koumoundouros, Giorgos
    The presence of skeletal anomalies in farmed teleost fish is currently a major problem in aquaculture, entailing economical, biological and ethical issues. The common occurrence of skeletal deformities in farmed fish and the absence of effective solutions for avoiding their onset or definitely culling out the affected individuals as early as possible from the productive cycle, highlight the need to improve our knowledge on the basic processes regulating fish skeletogenesis and skeletal tissues differentiation, modelling and remodelling. Severe skeletal anomalies may actually occur throughout the entire life cycle of fish, but their development often begins with slight aberrations of the internal elements....

  15. Larval and juvenile development of dusky grouper Epinephelus marginatus reared in mesocosms

    Cunha, M. E.; Re, P.; Quental-Ferreira, H.; Gavaia, Paulo J.; Pousão-Ferreira, P.
    The larval development of the dusky grouper Epinephelus marginatus up to the benthic juvenile stage is described in detail to establish a reference for their larval identification. Development is described in terms of ontogenetic changes in morphology, growth, pigmentation, fin structure and skeletal structure. Larvae were reared in mesocosms at a mean temperature of 24·3◦ C, salinity of 36·5, dissolved oxygen of 6·4mg l−1 and pH of 8·2. Newly hatched larvae had an estimated total length (LT) of 2·3 mm. On the second day post hatching the yolk was almost fully absorbed with traces of the oil globule still present, the...

  16. Glucose overload in yolk has little effect on the long-term modulation of carbohydrate metabolic genes in zebrafish (Danio rerio)

    Rocha, Filipa; Dias, J.; Engrola, S.; Gavaia, Paulo J.; Geurden, I.; Dinis, Maria Teresa; Panserat, S.
    The use of early nutritional stimuli to program metabolic pathways in fish is ill defined. Therefore, studies were undertaken with zebrafish to assess the effect of high glucose levels during the embryonic stage as a lifelong modulator of genes involved in carbohydrate metabolism. Genes related to carbohydrate metabolism were expressed at low levels at 0.2 and 1 day post-fertilization (dpf). However, from 4 dpf onwards there was a significant increase on expression of all genes, suggesting that all analysed pathways were active. By microinjection, we successfully enriched zebrafish egg yolk with glucose (a 43-fold increase of basal levels). Acute effects of glucose injection...

  17. Population genetics of Zostera noltii along the west Iberian coast: Consequences of small population size, habitat discontinuity and near-shore currents

    Diekmann, O. E.; Coyer, J. A.; Ferreira, J.; Olsen, J. L.; Stam, W. T.; Pearson, G. A.; Serrão, Ester
    The effects of oceanographic patterns on marine genetic biodiversity along the SW Iberian Peninsula are poorly understood. We addressed the question of whether gene flow in this region depends solely on geographic distance between isolated patches of suitable habitat or if there are superimposed effects correlated with other factors such as current patterns. Zostera noltii, the dwarf eelgrass, is the keystone habitat-structuring seagrass species on intertidal mudflats along the Iberian west coast. We used 9 microsatellite loci to analyze population genetic diversity and differentiation for all existing 8 populations from NW Spain (Ria de Vigo) to SW Spain (Puerto Real,...

  18. Convergent adaptation to a marginal habitat by homoploid hybrids and polyploid ecads in the seaweed genus Fucus

    Coyer, J. A.; Hoarau, G.; Pearson, G. A.; Serrão, Ester; Stam, W. T.; Olsen, J. L.
    Hybridization and polyploidy are two major sources of genetic variability that can lead to adaptation in new habitats. Most species of the brown algal genus Fucus are found along wave-swept rocky shores of the Northern Hemisphere, but some species have adapted to brackish and salt marsh habitats. Using five microsatellite loci and mtDNA RFLP, we characterize two populations of morphologically similar, muscoides-like Fucus inhabiting salt marshes in Iceland and Ireland. The Icelandic genotypes were consistent with Fucus vesiculosus x Fucus spiralis F1 hybrids with asymmetrical hybridization, whereas the Irish ones consisted primarily of polyploid F. vesiculosus.

  19. Feed-backs between genetic structure and perturbation-driven decline in seagrass (Posidonia oceanica) meadows

    Diaz-Almela, E.; Arnaud-Haond, S.; Vliet, M. S.; Álvarez, E.; Marbà, N.; Duarte, C. M.; Serrão, Ester
    We explored the relationships between perturbation-driven population decline and genetic/genotypic structure in the clonal seagrass Posidonia oceanica, subject to intensive meadow regression around four Mediterranean fish-farms, using seven specific microsatellites. Two meadows were randomly sampled (40 shoots) within 1,600 m2 at each site: the “impacted” station, 5–200 m from fish cages, and the “control” station, around 1,000 m downstream further away (considered a proxy of the pre-impact genetic structure at the site). Clonal richness (R), Simpson genotypic diversity (D*) and clonal sub-range (CR) were highly variable among sites. Nevertheless, the maximum distance at which clonal dispersal was detected, indicated by...

  20. Evolutionary and ecological trees and networks

    Hernández-García, E.; Herrada, E. A.; Rozenfeld, A. F.; Tessone, C. J.; Eguíluz, V. M.; Duarte, C. M.; Arnaud-Haond, S.; Serrão, Ester
    Evolutionary relationships between species are usually represented in phylogenies, i.e. evolutionary trees, which are a type of networks. The terminal nodes of these trees represent species, which are made of individuals and populations among which gene flow occurs. This flow can also be represented as a network. In this paper we briefly show some properties of these complex networks of evolutionary and ecological relationships. First, we characterize large scale evolutionary relationships in the Tree of Life by a degree distribution. Second, we represent genetic relationships between individuals of a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum Spanning...

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