Padrões de diversidade e estrutura de taxocenoses de anfíbios anuros: análise em multi-escala espacial

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relação entre macrofauna, agregação e atributos edáficos em sequência de culturas sob plantio direto

Pós-graduação em Agronomia (Agricultura) - FCA

NADPH- Diaphorase positive cardiac neurons in the atria of mice. A morphoquantitative study

Abstract Background The present study was conducted to determine the location, the morphology and distribution of NADPH-diaphorase positive neurons in the cardiac nerve plexus of the atria of mice (ASn). This plexus lies over the muscular layer of the atria, dorsal to the muscle itself, in the connective tissue of the subepicardium. NADPH- diaphorase staining was performed on whole-mount preparations of the atria mice. For descriptive purposes, all data are presented as means ± SEM. Results The majority of the NADPH-diaphorase positive neurons were observed in the ganglia of the plexus. A few single neurons were also observed. The number of NADPH-d positive neurons was 57 ± 4 (ranging from 39 to 79 neurons). The ganglion neurons were located in 3 distinct groups: (1) in the region situated cranial to the pulmonary veins, (2) caudally to the pulmonary veins, and (3) in the atrial groove. The largest group of neurons was located cranially to the pulmonary veins (66.7%). Three morphological types of NADPH-diaphorase neurons could be distinguished on the basis of their shape: unipolar cells, bipolar cells and cells with three processes (multipolar cells). The unipolar neurons predominated (78.9%), whereas the multipolar were encountered less frequently (5,3%). The sizes (area of maximal cell profile) of the neurons ranged from about 90 μm2to about 220 μm2. Morphometrically, the three types of neurons were similar and there were no significant differences in their sizes. The total number of cardiac neurons (obtained by staining the neurons with NADH-diaphorase method) was 530 ± 23. Therefore, the NADPH-diaphorase positive neurons of the heart represent 10% of the number of cardiac neurons stained by NADH. Conclusion The obtained data have shown that the NADPH-d positive neurons in the cardiac plexus of the atria of mice are morphologically different, and therefore, it is possible that the function of the neurons may also be different.

Evolutionary tendencies in flowers of Marantaceae with special reference to the style movement mechanism

One of the quickest plant movements ever known is made by the ´explosive´ style in Marantaceae in the service of secondary pollen presentation – herewith showing a striking apomorphy to the sister Cannaceae that might be of high evolutionary consequence. Though known already since the beginning of the 19th century the underlying mechanism of the movement has hitherto not been clarified. The present study reports about the biomechanics of the style-staminode complex and the hydraulic principles of the movement. For the first time it is shown by experiment that in Maranta noctiflora through longitudinal growth of the maturing style in the ´straitjacket´ of the hooded staminode both the hold of the style prior to its release and its tensioning for the movement are brought about. The longer the style grows in relation to the enclosing hooded staminode the more does its capacity for curling up for pollen transfer increase. Hereby I distinguish between the ´basic tension´ that a growing style builds up anyway, even when the hooded staminode is removed beforehand, and the ´induced tension´ which comes about only under the pressure of a ´too short´ hooded staminode and which enables the movement. The results of these investigations are discussed in view of previous interpretations ranging from possible biomechanical to electrophysiological mechanisms. To understand furthermore by which means the style gives way to the strong bending movement without suffering outwardly visible damage I examined its anatomical structure in several genera for its mechanical and hydraulic properties and for the determination of the entire curvature after release. The actual bending part contains tubulate cells whose walls are extraordinarily porous and large longitudinal intercellular spaces. SEM indicates the starting points of cell-wall loosening in primary walls and lysis of middle lamellae - probably through an intense pectinase activity in the maturing style. Fluorescence pictures of macerated and living style-tissue confirm cell-wall perforations that do apparently connect neighbouring cells, which leads to an extremely permeable parenchyma. The ´water-body´ can be shifted from central to dorsal cell layers to support the bending. The geometrical form of the curvature is determined by the vascular bundles. I conclude that the style in Marantaceae contains no ´antagonistic´ motile tissues as in Mimosa or Dionaea. Instead, through self-maceration it develops to a ´hydraulic tissue´ which carries out an irreversible movement through a sudden reshaping. To ascertain the evolutionary consequence of this apomorphic pollination mechanism the diversity and systematic value of hooded staminodes are examined. For this hooded staminodes of 24 genera are sorted according to a minimalistic selection of shape characters and eight morphological types are abstracted from the resulting groups. These types are mapped onto an already available maximally parsimonious tree comprising five major clades. An amazing correspondence is found between the morphological types and the clades; several sister-relationships are confirmed and in cases of uncertain position possible evolutionary pathways, such as convergence, dispersal or re-migration, are discussed, as well as the great evolutionary tendencies for the entire family in which – at least as regards the shape of hooded staminodes – there is obviously a tendency from complicated to strongly simplified forms. It suggests itself that such simplifying derivations may very likely have taken place as adaptations to pollinating animals about which at present too little is known. The value of morphological characters in relation to modern phylogenetic analysis is discussed and conditions for the selection of morphological characters valuable for a systematic grouping are proposed. Altogether, in view of the evolutionary success of Marantaceae compared with Cannaceae the movement mechanism of the style-staminode complex can safely be considered a key innovation within the order Zingiberales.

Características palinológicas de mieles de eucalipto (Eucalyptus sp.) y tréboles (Trifolium sp.) provenientes de la Provincia Fitogeográfica Pampeana Argentina

El objetivo de este trabajo fue estudiar el perfil polínico de mieles de tréboles y de eucalipto de la Provincia Fitogeográfica Pampeana Argentina, con el fin de contribuir a su caracterización palinológica. Se realizó un análisis polínico cualitativo y se aplicaron técnicas estadísticas descriptivas y multivariadas, para conocer la distribución de frecuencia de los pólenes y caracterizar cada origen floral, según los pólenes acompañantes y los años de cosecha. Se analizaron 81 muestras de miel, de cuatro cosechas diferentes. Se encontraron 41 tipos morfológicos de polen, cuya variación por muestra osciló entre dos y ocho. El taxón presente en más del 80% de las mieles fue Eucalyptus sp. Los principales pólenes acompañantes encontrados pertenecieron a los tipos Helianthus annuus y Carduus sp., para ambos orígenes florales estudiados, y a la familia de las Brassicaceae, para las mieles de tréboles. Los años de cosecha estudiados mostraron diferentes espectros polínicos.

Speciations of Mn and Fe in Fe-Mn nodules from the western part of the Clarion-Clipperton ore province

Hydrogenic forms of iron and manganese occurrence were studied in samples of ferromanganese nodules sampled within two polygons during Cruise 28 of R/V Dmitry Mendeleeev (1982) in the western part of the Clarion-Clipperton ore province. Contents of labile exchangeable Fe and Mn, amorphous hydroxides and poorly soluble compounds of Fe and Mn were analyzed. In nodules from DM28-2474 Polygon labile exchangeable Fe and Mn and amorphous hydroxides dominated; in nodules from DM28-2483 Polygon poorly soluble compounds dominated. Analysis of contents of labile forms of Fe and Mn occurrence in different morphological types of nodules distinguished predominantly hydrogenous botryoidal nodules, spheroidal and ellipsoidal intergrowth nodules, and hydrogenic-diagenetic discoid nodules.

Abundance patterns and isotopic signals of morphotypes of Globigerinoides ruber

The chemical composition of shells of the planktonic foraminifer Globigerinoides ruber (white) is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. Here, we investigate the occurrence through time and in space of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the central and the eastern Mediterranean Sea. In 115 samples representing two distinct time intervals (MIS 1-2 and MIS 9-12) at ODP Site 964 and the piston core GeoTü-SL96, we have defined three morphological types within this species and determined their relative abundances and stable isotopic composition. A quantitative analysis of morphological variation within G. ruber (white) in four samples revealed that the subjectively defined morphotypes occupy separate segments of a continuous and homogenous morphospace. We further show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the three morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within glacial and interglacial stages but their sign is systematically reversed between the two Sites. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1per mil, their understanding is essential for the interpretation of all G. ruber-based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary.

Skeletal trade-offs in coralline algae in response to ocean acidification

Ocean acidification is changing the marine environment, with potentially serious consequences for many organisms. Much of our understanding of ocean acidification effects comes from laboratory experiments, which demonstrate physiological responses over relatively short timescales. Observational studies and, more recently, experimental studies in natural systems suggest that ocean acidification will alter the structure of seaweed communities. Here, we provide a mechanistic understanding of altered competitive dynamics among a group of seaweeds, the crustose coralline algae (CCA). We compare CCA from historical experiments (1981-1997) with specimens from recent, identical experiments (2012) to describe morphological changes over this time period, which coincides with acidification of seawater in the Northeastern Pacific. Traditionally thick species decreased in thickness by a factor of 2.0-2.3, but did not experience a change in internal skeletal metrics. In contrast, traditionally thin species remained approximately the same thickness but reduced their total carbonate tissue by making thinner inter-filament cell walls. These changes represent alternative mechanisms for the reduction of calcium carbonate production in CCA and suggest energetic trade-offs related to the cost of building and maintaining a calcium carbonate skeleton as pH declines. Our classification of stress response by morphological type may be generalizable to CCA at other sites, as well as to other calcifying organisms with species-specific differences in morphological types.

Ultrastructure of Plant Leaf Cuticles in relation to Sample Preparation as Observed by Transmission Electron Microscopy

The leaf cuticular ultrastructure of some plant species has been examined by transmission electron microscopy (TEM) in only few studies. Attending to the different cuticle layers and inner structure, plant cuticles have been grouped into six general morphological types. With the aim of critically examining the effect of cuticle isolation and preparation for TEM analysis on cuticular ultrastructure, adaxial leaf cuticles of blue-gum eucalypt, grey poplar, and European pear were assessed, following a membrane science approach. The embedding and staining protocols affected the ultrastructure of the cuticles analysed. The solubility parameter, surface tension, and contact angles with water of pure Spurr's and LR-White resins were within a similar range. Differences were however estimated for resin : solvent mixtures, since Spurr’s resin is combined with acetone and LR-White resin is mixed with ethanol. Given the composite hydrophilic and lipophilic nature of plant cuticles, the particular TEM tissue embedding and staining procedures employed may affect sample ultrastructure and the interpretation of the results in physicochemical and biological terms. It is concluded that tissue preparation procedures may be optimised to facilitate the observation of the micro- and nanostructure of cuticular layers and components with different degrees of polarity and hydrophobicity.

Mixed synapses discovered and mapped throughout mammalian spinal cord.

Previously, synaptic activity in the spinal cord of adult mammals was attributed exclusively to chemical neurotransmission. In this study, evidence was obtained for the existence, relative abundance, and widespread distribution of "mixed" (chemical and electrical) synapses on neurons throughout the spinal cords of adult mammals. Using combined confocal microscopy and "grid-mapped freeze fracture," 36 mixed synapses containing 88 "micro" gap junctions (median = 45 connexons) were found and mapped to 33 interneurons and motor neurons in Rexed laminae III-IX in cervical, thoracic, and lumbosacral spinal cords of adult male and female rats. Gap junctions were adjacent to presumptive active zones, where even small gap junctions would be expected to increase synaptic efficacy. Two morphological types of mixed synapse were discerned. One type contained distinctive active zones consisting of "nested" concentric toroidal deformations of pre- and postsynaptic membranes, which, because of their unusual topology, were designated as "synaptic sombreros." A second type had gap junctions adjacent to active zones consisting of broad, flat, shallow indentations of the plasma membrane. Morphometric analysis indicates that mixed synapses correspond to 3-5% of all synapses on the somata and proximal dendrites, but, because of their subcellular location and morphology, they could represent 30-100% of excitatory synapses. The relative abundance of mixed synapses on several classes of neurons in spinal cords of adult rats suggests that mixed synapses provide important but previously unrecognized pathways for bidirectional communication between neurons in the mammalian central nervous system.

Nietzsche, la pulsion, l’histoire

Cette étude vise à comprendre le rôle de l’histoire dans la philosophie de Nietzsche et à faire ressortir son lien étroit avec l’articulation du corps vivant comme fil conducteur philosophique. Notre objectif principal est de montrer comment cette philosophie aphoristique a su maintenir les préoccupations historiographiques de jeunesse en permutant leur sens à l’aune de la pulsionnalité interprétative du corps. Prenant notre départ des considérations critiques écrites lors de son professorat à Bâle, nous démontrons que le sens historique se manifeste alors comme une sensibilité historique déterminée par une saisie intuitive, mais existentiellement difficile, du passé. Nous procédons ensuite à décrire comment le renouveau philosophique de sa période intermédiaire peut être vu comme une réduction pathologique de l’histoire de la métaphysique qui emprunte ses éléments critiques au scepticisme de Michel de Montaigne, à l’évolutionnisme naissant et au développement du néo-kantisme. Cette réduction, qui ramène l’expression des valeurs morales et métaphysiques au corps vécu (Leib). Par sa déconstruction de la subjectivité au profit d’une réalité pulsionnelle primordiale, mais irréductible, nous démontrons ensuite comment Nietzsche a su réinterpréter l’hérédité biologique comme une mémoire physiologique incorporée dont l’expression première est la reconduction de la notion d’espèce à celle de type. Enfin, par un retour à la sensibilité historique et notre analyse du phénomène historique en tant que tel, nous proposons de comprendre l’articulation ultime de la philosophie nietzschéenne comme une philosophie historique qui ne cherche pas à comprendre ou à expliquer le devenir, mais en opérer la synthèse par le truchement de « l’instant décisif ».

Nietzsche, la pulsion, l’histoire

Cette étude vise à comprendre le rôle de l’histoire dans la philosophie de Nietzsche et à faire ressortir son lien étroit avec l’articulation du corps vivant comme fil conducteur philosophique. Notre objectif principal est de montrer comment cette philosophie aphoristique a su maintenir les préoccupations historiographiques de jeunesse en permutant leur sens à l’aune de la pulsionnalité interprétative du corps. Prenant notre départ des considérations critiques écrites lors de son professorat à Bâle, nous démontrons que le sens historique se manifeste alors comme une sensibilité historique déterminée par une saisie intuitive, mais existentiellement difficile, du passé. Nous procédons ensuite à décrire comment le renouveau philosophique de sa période intermédiaire peut être vu comme une réduction pathologique de l’histoire de la métaphysique qui emprunte ses éléments critiques au scepticisme de Michel de Montaigne, à l’évolutionnisme naissant et au développement du néo-kantisme. Cette réduction, qui ramène l’expression des valeurs morales et métaphysiques au corps vécu (Leib). Par sa déconstruction de la subjectivité au profit d’une réalité pulsionnelle primordiale, mais irréductible, nous démontrons ensuite comment Nietzsche a su réinterpréter l’hérédité biologique comme une mémoire physiologique incorporée dont l’expression première est la reconduction de la notion d’espèce à celle de type. Enfin, par un retour à la sensibilité historique et notre analyse du phénomène historique en tant que tel, nous proposons de comprendre l’articulation ultime de la philosophie nietzschéenne comme une philosophie historique qui ne cherche pas à comprendre ou à expliquer le devenir, mais en opérer la synthèse par le truchement de « l’instant décisif ».

Chemical and isotopic compositions of hydrothermal manifestations and minerals from the Broken Spur hydrothermal field

A representative collection of hydrothermal manifestations was sampled practically from all hydrothermal mounds of the Broken Spur hydrothermal vent field with use of the Mir manned submersibles during three cruises of R/V Akademik Mstislav Keldysh. Mineral associations characteristic for different morphological types of sulfide ores from hydrothermal pipes, plates, and diffusers are assessed. Particular attention is paid to distribution of minor elements and their distribution patterns determined by mineralogical zonation. Measured isotopic composition of sulfur in sulfide minerals varies from 0.4 to 5.2 per mil that indicates their similarity with ores from the Snake Pit vent field and is related to dilution of hot ore-bearing solutions by seawater and reduction of water sulfate ions to H2S with heavy isotopic composition.