Assimilate partitioning in leaves of the raffinose-storing herb Lamium album L.: the effects of altering source-sink balance

In Lamium album, sucrose and raffinose-family oligosaccharides are the major products of photosynthesis that are stored in leaves. Using gas analysis and 14CO2 feeding, we compared photosynthesis and the partitioning of recently-fixed carbon in plants where sink activity was lowered by excision of flowers and chilling of roots with those where sink activity was not modified. Reduction in sink activity led to a reduction in the maximum rate of photosynthesis, to retention of fixed carbon in source leaves and to the progressive accumulation of raffinose-family oligosaccharides. This ultimately affected the extractable activities of invertase and sucrose phosphate synthase. At the end of the light period, invertase activity was significantly higher in treated plants. By contrast sucrose phosphate synthase activity was significantly lower in treated plants. We propose that reducing sink activity in L. album is associated with a shift in metabolism away from starch and sucrose synthesis and towards sucrose catabolism, galactinol utilisation and the synthesis of raffinose-family oligosaccharides.

N-partitioning, nitrate reductase and glutamine synthetase activities in two contrasting varieties of maize

In order to identify useful parameters for maize genetic breeding programs aiming at a more efficient use of N, two maize varieties of contrasting N efficiency, Sol da Manhã NF (efficient) and Catetão (inefficient) were compared. Experiments were carried out under field and greenhouse conditions, at low and high N levels. The parameters analysed included total and relative plant and grain N content, biomass and the activities of nitrate reductase and glutamine synthetase in different parts of the plant. It was found that the translocation efficiency of N and photoassimilates to the developing seeds and the source-sink relations were significantly different for the two varieties. N content of the whole plant and grain, cob weight and the relative ear dry weight were useful parameters for characterizing the variety Sol da Manhã NF as to its efficient use of N. Enzymes activity of glutamine synthetase (transferase reaction) and nitrate reductase did not differ among the varieties.

Assemblages of drosophilids (Diptera, Drosophilidae) in mangrove forests: community ecology and species diversity

Brazilian fauna of drosophilids has been researched in various ecosystems, but those in mangrove forests remain overlooked in Brazil and elsewhere. The present study attempts to characterise the assemblages of drosophilids of this environment, based on 28 collections taken in three mangrove areas in Santa Catarina Island, southern Brazil. The three mangroves surveyed were different in their surroundings, which varied from highly urbanised areas to conservation areas with natural vegetation. Overall, 69 species were collected, and no remarkable difference was detected in species composition and abundances or in the richness, evenness and heterogeneity between sites. The species abundance distribution observed fitted to a theoretical lognormal distribution in the three mangroves. The species richness scored and the performance of the species richness estimators showed an unexpectedly high diversity, considering the very low floristic diversity and the harsh conditions of the environment. Regarding species composition and abundances, the drosophilid mangrove assemblages were shown to be more similar to those found in open environments, with a marked dominance of exotic species. Finally, considering the apparent lack of feeding and breeding sites, we suggest that mangrove forests are acting as sink habitats for the drosophilids populations.

Defoliation of strawberry mother plants for the production of runner tips

The objective of this work was to determine the sink-source relationships and their effects on the number and growth of runner tips of 'Camino Real' strawberry stock plants. Three types of sources were evaluated: one defoliation at 96 days after planting (DAP), two defoliations at 50 and 96 DAP, and mother plants without defoliation. Four types of sink were accessed: runner tips collected weekly and monthly, four stolons with rooted runner tips in pots, and four freely-grown stolons. A completely randomized experimental design was used in a split-plot arrangement, with four replicates. The source types were placed in the plots, and sink types in the subplots. The number of runner tips, the crown diameter, and the dry matter mass were determined. Number and growth of tips were higher on plants without defoliation, and decreased 44.7% on twice-defoliated mother plants. The two-defoliation management did not reduce runner tip dry matter mass only on plants with rooted stolons, which produced runner tips 50% heavier. Defoliation of mother plants bearing rooting stolons can be used to reduce their growth, without reducing the emission and growth of runner tips.

Potencial uso de serpentinito no armazenamento mineral do CO2

Rising anthropogenic CO2 emissions are considered a major contributor to the greenhouse effect. There are several options for reducing atmospheric CO2 levels, and among these alternatives, Carbon Capture and Storage (CCS) has been identified as an effective and promising approach. This work investigated the feasibility of using serpentinite as a vehicle for carbon storage presenting a source-sink match. The main results of the work confirmed that serpentinite is appropriate for the carbonation process due to the high concentration of Mg in its composition.

Ecological relations between mangrove leaf litter and the spatial distribution of the gastropod Melampus coffeus in a fringe mangrove forest

Leaf litter represents a food source to many organisms that may directly contribute to organic matter decomposition. In addition, the physical presence of these vegetal detritus contributes for the modification of some environmental areas and produce microhabitats that may act as a refuge against predators and desiccation for many animals. The pulmonate gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) is a very common specie in Atlantic Coast mangrove forests and feeds on fallen mangrove leaves. It was hypothesized that the spatial distribution of Melampus coffeus is directly affected by mangrove leaf litter biomass deposition. Thus, this research aimed at evaluating the spatial distribution of these gastropods in relation to the biomass of mangrove leaf litter through a twelve-month period. The study area was established in the middle estuary of Pacoti River, state of Ceará, Brazil where two adjacent zones with different topographic profiles were determined. Samples of Melampus coffeus and leaf litter were collected monthly, throughout a year, from the mangrove ground surface. The results indicated that the presence of twigs in mangrove litter favor the occupation by smaller individuals of M. coffeus, probably because smaller individuals are more susceptible to predator attacks and desiccation than larger ones, and twigs and branches may provide a safe microhabitat.

Brazil: an emerging military power? The problem of the use of force in Brazilian international relations in the 21st century

The central goal of this paper is thinking about the Brazilian military power and its linking to the international ambitions of the country in the 21st century. After a comparative analysis to other BRICs and with a historical one about Brazil's strategic irrelevance, we aim to establish what the minimum military capacity Brazil would need in order to meet the country's latest international interests. Similarly, it will be discussed if the National Strategy of Defense, approved in 2008, and the recent strategic agreements signed with France represent one more step toward this minimum military capacity.

A new Strategic Dialogue: Brazil-US relations in Lula's presidency (2003-2010)

The aim of this article is to examine Brazil and the United States bilateral relations from 2003/2010 and their strategic patterns during the Presidency of Luis Inácio Lula da Silva. The goal is to understand the development of this dialogue in the 21st century and its previous background in the Post Cold War world, identifying its evolution and change due to Brazil's growing regional and global role and US relative position

China's rising Soft Power: the role of rhetoric in constructing China-Africa relations

As China turns increasingly to the cultivation of soft power in the course of developing its foreign policy, the use of political rhetoric and its explicit and implicit audiences become more and more important, both on a bilateral level and within the international arena at large. Using the case of China's relations with African countries, this article examines key themes within China's diplomatic narrative regarding its role on the African continent and contrasts with Western and African responses.

South-South relations and the English School of International Relations: Chinese and Brazilian ideas and involvement in Sub-Saharan Africa

The rise of large developing countries has led to considerable discussions of re-balancing global relations and giving greater priority to understanding South-South relations. This paper, in exploring the central ideas of Chinese and Brazilian foreign policy and the behavior of these two rising Southern countries toward Sub-Saharan Africa, argues that the English School of International Relations is well suited to understanding the intentions and actions that characterize South-South relations.

Macau in China's relations with the lusophone world

After the transfer of the Portuguese administration to China, Macau kept its role as a bridge between East and West, inspired in the Portuguese settlement 500 years ago. The pragmatism of the Chinese central government, using the Lusophone specificities of this Special Administrative Region, supported the creation of the Forum for Economic and Trade Cooperation between China and the Portuguese-speaking Countries, reviving the statute of the Portuguese language and culture in its own territory.