COMPORTAMENTO DE MOVIMENTAÇÃO HORIZONTAL E VERTICAL DA TARTARUGA-DE-COURO Dermochelys coriacea

The general biology of the leatherback turtle (Dermochelys coriacea) still remains poorly understood, mainly because of its life-history characteristics. D. coriacea is a highly pelagic cosmopolitan species that spends most of its life in the open sea, and is able to perform transoceanic migrations from reproductive to foraging zones and back. Over their long travels throughout the sea, the leatherback turtle moves both horizontally (e.g., migrations) and vertically (i.e. dives) in response to different factors, like searching for suitable habitats for growth, feeding and reproduction. The present article is a  comprehensive review of the current knowledge about the horizontal and vertical behavioral movements performed by D. coriacea. An analysis of how these behaviors are influenced by different factors governing the ecology of this species is presented. Some studies indicate that oceanographic features are the key factors determining the movement patterns observed for D. coriacea, mainly during their geographic migrations and residence in feeding zones. In short, the leatherback turtle employs different navigation and dispersion strategies while in each different oceanic zone. On certain occasions, individuals may disperse in different directions while on other occasions they may follow a roughly uniform path across the sea. Movement trends during the nesting period vary between different oceanic zones depending on local topography and on the behavioral strategy adopted by the nesting females with respect to how to invest energy during the reproductive season (e.g., actively searching for prey versus limiting activity to reduce metabolic rate).La biología de la tortuga laúd (Dermochelys coriacea) aún es relativamente poco conocida, fundamentalmente debido a sus hábitos de vida. D. coriacea es una especie altamente pelágica y cosmopolita que pasa la mayor parte da su vida en el océano abierto, y que puede realizar migraciones transoceánicas entre áreas de reproducción y de alimentación. En sus extensos desplazamientos a través del océano,la tortuga de laúd ejecuta movimientos tanto horizontales (ej.  migraciones) como verticales (ej. buceos) que constituyen respuestas de comportamiento a diferentes factores como búsqueda de un ambiente apropiado para el crecimiento, alimentación y reproducción, entre otros. En este trabajo, presentamos una amplia revisión acerca del estado actual del conocimiento de los movimientos horizontales y verticales realizados por D. coriacea, analizando como estos comportamientos son influenciados por diferentes factores que determinan la ecología de la especie. Los estudios indican que las características oceanográficas constituyen factores claves en la determinación de los patrones de movimiento registrados para D. coriacea, principalmente durante lasmigraciones y durante su permanencia en áreas de alimentación. En general la tortuga laúd utiliza diferentes estrategias de navegación y dispersión en las diferentes regiones del océano, en algunos casos, los individuos de la especie se dispersan ampliamente en varias direcciones y en otros casos siguen un patrón relativamente uniforme y persistente a través del océano. Las tendencias de movimiento durante el período de desove varían en las diferentes zonas oceánicas, influenciadas por la topografía del lugar y por la estrategia de comportamiento  de las hembras en relación a los costos energéticos durante la temporada reproductiva (ej. comportamiento de búsqueda de alimento versus poca actividad para reducir el gasto metabólico).A biologia da tartaruga-de-couro (Dermochelys coriacea) é ainda relativamente pouco conhecida,fundamentalmente devido a seus hábitos de vida. D. coriacea é uma espécie altamente pelágica e cosmopolita que passa a maior parte da sua vida no oceano aberto, e que pode realizar migrações transoceânicas entre áreas de reprodução e de alimentação. Ao longo de sua extensa movimentação por porções oceânicas, a tartarugade-couro executa movimentos horizontais (ex. migrações) e verticais (ex. mergulhos) que constituem respostas comportamentais a diferentes fatores, como busca de ambiente apropriado para o crescimento, a alimentação e a reprodução, entre outros. No presente artigo, apresentamos uma revisão abrangente acerca do estado atual do conhecimento sobre os movimentos comportamentais horizontais e verticais realizados por D. coriacea, analisando como estes comportamentos são influenciados por diferentes fatores que regem a ecologia da espécie. Os estudos indicam que as feições oceanográficas constituem fatores-chave na determinação dos padrões de movimentação registrados para D. coriacea, principalmente durante as migrações e durante sua permanência em áreas de alimentação. Em geral a tartaruga-de-couro utiliza diferentes estratégias de navegação e dispersão nas diferentes regiões oceânicas, em alguns casos, os indivíduos da espécie se dispersam amplamente em varias direções e, em outros casos, seguem um padrão relativamente uniforme e persistente através do oceano. As tendências de movimentação durante o período de desova variam nas diferentes regiões oceânicas, influenciadas pela topografia do local e pela estratégia comportamental das fêmeas em relação aos custos energéticos durante a temporada reprodutiva (ex. comportamento de busca de alimento versus pouca atividade para reduzir o gasto metabólico)

Effect of bacterial inoculation, plant genotype and developmental stage on root-associated and endophytic bacterial communities in potato (Solanum tuberosum)

Beneficial bacteria interact with plants by colonizing the rhizosphere and roots followed by further spread through the inner tissues, resulting in endophytic colonization. The major factors contributing to these interactions are not always well understood for most bacterial and plant species. It is believed that specific bacterial functions are required for plant colonization, but also from the plant side specific features are needed, such as plant genotype (cultivar) and developmental stage. Via multivariate analysis we present a quantification of the roles of these components on the composition of root-associated and endophytic bacterial communities in potato plants, by weighing the effects of bacterial inoculation, plant genotype and developmental stage. Spontaneous rifampicin resistant mutants of two bacterial endophytes, Paenibacillus sp. strain E119 and Methylobacterium mesophilicum strain SR1.6/6, were introduced into potato plants of three different cultivars (Eersteling, Robijn and Karnico). Densities of both strains in, or attached to potato plants were measured by selective plating, while the effects of bacterial inoculation, plant genotype and developmental stage on the composition of bacterial, Alphaproteobacterial and Paenibacillus species were determined by PCR-denaturing gradient gel-electrophoresis (DGGE). Multivariate analyses revealed that the composition of bacterial communities was mainly driven by cultivar type and plant developmental stage, while Alphaproteobacterial and Paenibacillus communities were mainly influenced by bacterial inoculation. These results are important for better understanding the effects of bacterial inoculations to plants and their possible effects on the indigenous bacterial communities in relation with other plant factors such as genotype and growth stage

Cultivation of hitherto-uncultured bacteria belonging to the Verrucomicrobia subdivision 1 from the potato (Solanum tuberosum L.) rhizosphere

The role of dominant bacterial groups in the plant rhizosphere, e.g., those belonging to the phyla Acidobacteria and Verrucomicrobia, has, so far, not been elucidated, and this is mainly due to the lack of culturable representatives. This study aimed to isolate hitherto-uncultured bacteria from the potato rhizosphere by a combination of cultivation approaches. An agar medium low in carbon availability (oligotrophic agar medium) and either amended with potato root exudates or catalase or left unamended was used with the aim to improve the culturability of bacteria from the potato rhizosphere. The colony forming unit numbers based on colonies and microcolonies were compared with microscopically determined fluorescence-stained cell numbers. Taxonomical diversity of the colonies was compared with that of library clones made from rhizosphere DNA, on the basis of 16S rRNA gene comparisons. The oligotrophic media amended or not with catalase or rhizosphere extract recovered up to 33.6% of the total bacterial numbers, at least seven times more than the recovery observed on R2A. Four hitherto-uncultured Verrucomicrobia subdivision 1 representatives were recovered on agar, but representatives of this group were not found in the clone library. The use of oligotrophic medium and its modifications enabled the growth of colony numbers, exceeding those on classical agar media. Also, it led to the isolation of hitherto-uncultured bacteria from the potato rhizosphere. Further improvement in cultivation will certainly result in the recovery of other as-yet-unexplored bacteria from the rhizosphere, making these groups accessible for further investigation, e.g., with respect to their possible interactions with plants

Shedding light on zooplankton diversity from the Congo River Basin

peer reviewedThe Congo River Basin is the second largest in the world, and its plankton biota remains completely unknown. We studied the zooplankton diversity across 1700 km of the main channel (from the cities of Kisangani to Kinshasa) and subsequently in the mouths of the 25 largest tributaries during 2013 (N=39), and across 500 km of Kasai-Kwa River and tributaries in 2015 (N=25). We recorded 135 zooplankton species (26 for Testate Amoebae, 56 for Rotifera, 27 for Cladocera and 26 for Copepoda). At least five cladoceran and four copepod species are new. A non-metric multidimensional statistical analysis with Bray Curtis dissimilarity revealed that the zooplankton composition within Congo main channel was more similar than within the mouths of several tributaries and the Kasai-Kwa River basin. In the later, the tributaries were distinct from each other and from the main channel of Kasai River. A distance-based redundancy analysis using Bray-Curtis dissimilarity on abundance data revealed two main groups of species and limnological variables, one comprising sites with high total suspended matter, conductivity, chlorophyll, phytoplanktonabundance (white water rivers), and other with sites with high transparency and dissolved organic carbon concentration (black water rivers). Zooplankton diversity was uniform in the Congo main channel and in the Kasai-Kwa River, with low difference among sites. There was also a distinct third group, unrelated to variables. This study reveals a high diverse zooplankton community in the Congo basin, with new species and distinct community between the studied rivers, but homogeneous along each one