Floral resources used by insects in a grassland community in Southern Brazil

The goal of the present study was to identify plant species used as food source, the floral resources utilized, and the insects that visit flowers in a grassland community in southern Brazil. The study was carried out in an area of one hectare, located in a grassland formation in the Parque Estadual de Itapuã, State of Rio Grande do Sul, Brazil. The flowering pattern was seasonal, and richness and abundance of insects was higher during the period of high resource availability. Flowers of 106 species of angiosperms (73 genera and 34 families) were used as source of floral resources for 219 species (2,767 specimens) of insects. A total of 91.5% of plant species were visited by bees, 53.8% by flies, 34.9% by wasps, 22.6% by butterflies, and 12.3% by beetles. Nectar was the main resource consumed by the visitors (41.1%). Asteraceae was the richest (38 spp.) and most visited family, with 63.1% of the species and 49.5% of all specimens of recorded insects. Bees were the most representative insects (33.2% spp., 65% indiv.), followed by flies (26.9% spp., 16.5% indiv.), wasps, butterflies and beetles. 40 plant species were considered important resources for the floral visitors' community, due to high number of, both, species and individuals recorded in their flowers. The family Asteraceae as a species set was the main floral resource used by insect visitors through the year and has great importance for the maintenance of populations of many species of bees, flies, wasps and butterflies in the studied area.

Estratégia reprodutiva de Cochlospermum orinocense (Kunth) Steud.: fenologia, biologia floral e sistema de cruzamento em uma espécie pioneira de florestas na Amazônia

Cochlospermum orinocense (Kunth) Steud. é uma espécie arbórea freqüente em clareiras, na borda da floresta e em florestas secundárias na Amazônia. Dados da fenologia, biologia floral e sistema de cruzamento foram obtidos em indivíduos na borda de um fragmento de 80 ha de floresta Amazônica primária, de terra firme, na ilha de São Luís, MA. Cochlospermum orinocense é uma espécie decídua com floração anual precoce, intensa e sincronizada na estação seca. Suas flores hermafroditas e levemente zigomorfas estão dispostas em inflorescências terminais e têm duração de um dia. Cada ovário possui em média 250 óvulos e o androceu é composto por cerca de 160 anteras, de deiscência poricida, apresentando 81,6% de pólen viável e razão P/O de 16.019,2. A antese é diurna e as flores são polinizadas predominantemente por abelhas solitárias Centris spp. A espécie é autocompatível (IAI = 0,98) com alta eficácia reprodutiva (ER = 0,81), sendo a apomixia reduzida ou nula. Distribuição agrupada e floração intensa e sincronizada na seca, em árvores decíduas, induzem alta eficiência na polinização, sendo a fecundidade limitada pelos recursos da planta e não por pólen. Geitonogamia, a forma mais freqüente de endogamia, pode assegurar o sucesso reprodutivo em indivíduos isolados na floresta, mas induz forte depressão endogâmica. Alta densidade e a forma agrupada com que a espécie predominantemente ocorre, favorecendo a alogamia, podem permitir alta eficiência reprodutiva e fecundidade ao minimizar a depressão endogâmica.

Biologia floral e polinização de Casearia grandiflora, Casearia. javitensis e Lindackeria paludosa (Flacourtiaceae) na região de Manaus, AM

A biologia floral, polinização e sistema reprodutivo de Casearia grandiflora Cambess., C. javitensis Kunth e Lindackeria paludosa (Benth.) Gilg foram estudados no campus da Universidade Federal do Amazonas, Manaus, Brasil (03°04'34" S e 59°57'50" W), durante o período de novembro 2003 a dezembro 2004. Foram realizadas observações sobre morfologia, biologia floral e visitantes florais. O sistema reprodutivo e o sucesso reprodutivo foram determinados através de polinizações experimentais no campo. As flores são hermafroditas ou estaminadas em Lindackeria paludosa e hermafroditas nas espécies de Casearia que emitem um odor adocicado durante a antese e cujo pólen possui alta fertilidade. As flores de Lindackeria paludosa e Casearia javitensis abrem durante a manhã, enquanto que as de Casearia grandiflora abrem durante a noite. Os principais polinizadores são moscas da família Syrphidae em espécies de Casearia e abelhas das famílias Apidae e Halictidae em L. paludosa. Os resultados das polinizações manuais indicam que Casearia grandiflora e Lindackeria paludosa são espécies autocompatíveis, ao contrário de Casearia javitensis, que é autoincompatível. As espécies apresentaram um alto potencial reprodutivo, mas baixo sucesso reprodutivo pré-emergente.

Biologia floral de Manilkara subsericea e de Sideroxylon obtusifolium (Sapotaceae) em restinga

Manilkara subsericea (Mart.) Dubard e Sideroxylon obtusifolium (Roem. & Schult.) T.D. Penn. apresentam inflorescências fasciculadas, com flores perfeitas, nectaríferas, odoríferas e hercogâmicas. Apresentam dicogamia protogínica e antese diurna. A corola é gamopétala, com a região basal dos lacínios formando um pequeno tubo. Os lacínios medianos, em ambas as espécies, curvam-se em direção ao eixo da flor, formando uma espécie de canaleta, na qual fica alojado o estame. As anteras são versáteis, extrorsas e rimosas. A liberação dos grãos de pólen ocorre na forma de nuvem por um mecanismo explosivo proveniente do acionamento do dispositivo lacínio-estame. As flores foram visitadas por abelhas, borboletas, besouros, moscas e Thysanoptera, sendo polinizadas pelas abelhas Xylocopa ordinaria e Apis mellifera, pela vespa Brachygastra lecheguana e pela borboleta Isanthrene incendiaria.

Photosynthetic responses of four tropical tree species grown under gap and understorey conditions in a semi-deciduous forest

Leaf CO2 assimilation (A) as a function of photosynthetic photon flux density (Q) or intercellular CO2 concentration (Ci) and chlorophyll fluorescence measurements were carried out on four tropical woody species growing in forest gap and understorey (Bauhinia forficata Link. and Guazuma ulmifolia Lam. as pioneers, and Hymenaea courbaril L. and Esenbeckia leiocarpa Engl. as non-pioneers). Chlorophyll fluorescence indicated similar acclimation capacities of photochemical apparatus to contrasting light environments irrespective to plant species. Maximum CO2 assimilation and quantum yield derived from A/Q curves indicated higher photosynthetic capacity in pioneer than in non-pioneer species in forest gap. However, the differences among species did not show a straightforward relation with their successional status regarding data derived from A/Q curves under understorey conditions. Both successional groups are able to sustain positive carbon balance under contrasting natural light availabilities, modifying photochemical and biochemical photosynthetic traits with similar phenotypic plasticity capacity.

Fenologia reprodutiva, biologia floral e polinização de Allamanda blanchetii, uma Apocynaceae endêmica da Caatinga

(Fenologia reprodutiva, biologia floral e polinização de Allamanda blanchetii, uma Apocynaceae endêmica da Caatinga). A fenologia reprodutiva, a biologia floral, o mecanismo de polinização e o sistema reprodutivo de Allamanda blanchetii A.DC. foram analisados em populações naturais na Fazenda Almas, Paraíba, Brasil. Allamanda blanchetii é uma espécie arbustiva, endêmica da Caatinga, com floração de fevereiro a julho e pico nos meses de março e abril. A frutificação acompanhou a floração e estendeu-se até o mês de setembro. As flores são tubulares e de coloração rosa, cuja forte hercogamia evita a autopolinização. O pólen é depositado na parte superior da cabeça do estilete (região não receptiva), ainda na fase de botão em pré antese (anteras deiscentes), caracterizando a apresentação secundária de pólen. As flores produzem uma média de 36,6 µL de néctar, o qual é o único recurso para os visitantes florais. Allamanda blanchetii é auto-incompatível e os resultados sugerem mecanismo de incompatibilidade de ação tardia. Seus atributos florais estão relacionados com as síndromes de melitofilia e psicofilia e, de fato, os polinizadores registrados foram a abelha Eulaema nigrita Lepeletier como principal polinizador e quatro espécies de borboletas que atuam como polinizadores secundários. A ocorrência de forte hercogamia, apresentação secundária de pólen e mecanismo de auto-incompatibilidade indicam o elevado grau de especialização dos sistemas de polinização e reprodução de A. blanchetii.

Sistema sexual e biologia floral de Pouteria ramiflora e P. torta (Sapotaceae)

Pouteria ramiflora e P. torta são espécies arbóreas, simpátricas no Bioma Cerrado, e foram estudadas da Reserva Ecológica do Clube Caça e Pesca Itororó, Uberlândia-MG com o objetivo de comparar os vários aspectos de sua biologia reprodutiva. As fenofases foram avaliadas semanalmente e quantificadas quanto à intensidade. Os dados de biologia floral, sistema reprodutivo, sistema sexual e visitantes florais foram obtidos no campo e/ou no laboratório. As espécies apresentaram caducifolia no final da seca, brotação na transição da seca para o período chuvoso, floração na seca e maturação dos frutos na época chuvosa. Ambas possuem flores tubulares, pequenas e esverdeadas, nectaríferas e com viabilidade polínica alta. São autoestéreis e não agamospérmicas e apresentaram baixo sucesso de frutificação na polinização aberta. P. torta é hermafrodita, com flores protogínicas e hercogâmicas, enquanto P. ramiflora é morfologicamente ginomonóica e funcionalmente monóica. O fluxo de pólen aparentemente baixo entre as plantas e o aborto de frutos jovens resultaram em um pequeno sucesso de frutificação proveniente das polinizações naturais. Ambas as espécies são visitadas por diversos pequenos insetos, como borboletas, mariposas, dípteros e abelhas.

Floristic composition and phytogeography of the tree component of Araucaria Forest fragments in southern Brazil

The present study examined the floristic composition of three fragments of Araucaria Forest (AF) in the Planalto Catarinense region of southern Brazil as well as the floristic contextualization of these areas in relation to other remnant AF sites. Three AF fragments at different altitudes were analyzed in the municipalities of Campos Novos, Lages, and Painel. Fifty 200 m² plots were examined in each fragment and all of the trees with CBH (circumference at breast height) > 15.7 cm were identified. In order to floristically contextualize the study fragments, comparisons were made with other remnant AF sites by way of dendrograms and NMDS (Non-metric multidimensional scaling). Environmental and spatial variables were plotted on the diagram produced by the NMDS to evaluate their influence on the floristic patterns encountered. The forest fragments studied demonstrated high floristic heterogeneity, indicating that AFs cannot be considered homogeneous formations and they could be classified into 3 phytogeographical categories: i) high altitude areas influenced by cloud cover/fog, including the Painel region; ii) areas of lesser altitude and greater mean annual temperatures situated in the Paraná River basin, and iii) areas situated in the Paraná and Upper-Uruguay river basins and the smaller basins draining directly into the southern Atlantic, near Campos Novos and Lages. The environmental variables most highly correlated with species substitutions among the sites were altitude, mean annual temperature, and the mean temperature of the most humid trimester.

Influence of edaphic variables on the floristic composition and structure of the tree-shrub vegetation in typical and rocky outcrop cerrado areas in Serra Negra, Goiás State, Brazil

The present study analyzed the influence of edaphic variables on the floristic compositions and structures of the arboreal and shrub vegetation of typical cerrado (TC) and rocky outcrop cerrado (RC) communities in the Serra Negra mountain range in Piranhas Municipality, Goiás State, Brazil. Ten 20×50m plots were established in each community, and all individuals with minimum diameters ³5cm measured at 30cm above soil level were sampled. Composite soil samples were collected at 0-20cm depths in each plot for physical and chemical analyses. The proportions of above-ground rock cover work also estimated in each RC plot. A total of 2,009 individuals (83 species, 69 genera, and 34 families) were recorded. Qualea parviflora was the only species consistently among the 10 most structurally important taxa in both communities, and was considered a generalist species. The observed and estimated species richnesses were greater in RC than in TC, although plant basal areas and heights did not differ between them. There were positive correlations between rock cover×plant density and rock cover×basal areas. TWINSPAN and PCA analysis separated the TC and RC plots, and three RC habitat specialist species (Wunderlichia mirabilis, Norantea guianensis, and Tibouchina papyrus) were identified. Soil variables were found to have greater effects on the species compositions of the TC and RC sites than the geographic distances between sampling plots. According to CCA analysis, the exclusive (or more abundant species) of each community were correlated with soil variables, and these variables therefore determined the selection of some species and influenced the differentiation of the vegetation structures of the communities studied.

The tree-shrub vegetation in rocky outcrop cerrado areas in Goiás State, Brazil

We describe the floristic composition of the tree-shrub vegetation in 10 areas of rocky outcrop cerrado in Goiás State, Brazil. Ten 20×50m plots (totaling 1ha) were established and all of the individuals with diameters at 30cm above soil level (DB30) ³5cm were included in the sampling. Comparative analyses of the flora were realized using similarity indices (Sørensen and Czekanowski), classification analysis (TWINSPAN), and the Mantel test. A total of 13,041 tree-shrub individuals were sampled, distributed among 219 species, 129 genera and 55 families. Fabaceae was the most well-represented family, followed by Myrtaceae, Melastomataceae, Vochysiaceae, Malphigiaceae, and Rubiaceae. Fully 42.3% of the comparisons evaluated by the Sørensen index were >0.50, while all the values were <0.50 for the Czekanowski index, with the exception of Jaraguá and Mara Rosa areas. The TWINSPAN classification generated four divisions and, in general, only the differences in the size of the population were responsible for the groupings. The Mantel test indicated that there was no relationship between floristic similarity and the distances between the areas (r=0.32, P=0.05). It therefore appears that the areas of rocky outcrop cerrado in Goiás State are relatively floristically homogeneous and that they are principally distinguished by the differences in the sizes of the populations of their dominant species, and the presence of exclusive species in certain areas.

Diurnal changes in storage carbohydrate metabolism in cotyledons of the tropical tree Hymenaea courbaril L. (Leguminosae)

The cotyledons of Hymenaea courbaril store large amounts of xyloglucan, a cell wall polysaccharide that is believed to serve as storage for the period of seedling establishment. During storage mobilisation, xyloglucan seems to be degraded by a continuous process that starts right after radicle protrusion and follows up to the establishment of photosynthesis. Here we show evidence that events related to the hydrolases activities and production (α-xylosidase, β-galactosidase, β-glucosidase and xyloglucan endo-β-transglucosilase) as well as auxin, showed changes that follow the diurnal cycle. The period of higher hydrolases activities was between 6pm and 6am, which is out of phase with photosynthesis. Among the enzymes, α-xilosidase seems to be more important than β-glucosidase and β-galactosidase in the xyloglucan disassembling mechanism. Likewise, the sugars related with sucrose metabolism followed the rhythm of the hydrolases, but starch levels were shown to be practically constant. A high level of auxin was observed during the night, what is compatible with the hypothesis that this hormone would be one of the regulators of the whole process. The probable biological meaning of the existence of such a complex control mechanism during storage mobilisation is likely to be related to a remarkably high level of efficiency of carbon usage by the growing seedling of Hymenaea courbaril, allowing the establishment of very vigorous seedlings in the tropical forest.

One-winged Drosophila subobscura: a phenotype with an obscure genetic basis

A line of one-winged Drosophila subobscura was studied. The absent wing is substituted by a bulky structure with macro and microchaetes, showing a thoracic appearance. Genetic crosses showed that there is no way to select for the trait by simple crossing. The number of one-winged flies in the various generations was always low. In one case a wingless fly was also obtained. The trait presents an unknown genetic pattern.

In vitro radioautographic studies of the biodistribution of radiopharmaceuticals on blood elements

In the present study we evaluated the binding of the radiopharmaceuticals sodium pertechnetate (Na 99mTcO4), methylenediphosphonic acid (99mTc-MDP) and glucoheptonate acid (99mTc-GHA) to blood elements using centrifugation and radioautographic techniques. Heparinized blood was incubated with the labelled compounds for 0, 1, 2, 3, 4, 6 and 24 h. Plasma (P) and blood cells (BC) were isolated and precipitated with 5% trichloroacetic acid (TCA), and soluble (SF) and insoluble fractions (IF) were separated. Blood samples were prepared (0 and 24 h) and coated with LM-1 radioautographic emulsions and percent radioactivity (%rad) in P and BC was determined. The binding of Na 99mTcO4 (%rad) to P was 61.2% (0 h) and 46.0% (24 h), and radioautography showed 63.7% (0 h) and 43.3% (24 h). The binding to BC was 38.8% (0 h) and 54.0% (24 h), and radioautography showed 36.3% (0 h) and 56.7% (24 h). 99mTc-MDP study presented 91.1% (0 h) to P and 87.2% (24 h), and radioautography showed 67.9% (0 h) and 67.4% (24 h). The binding to BC was 8.9% (0 h) and 12.8% (24 h), and radioautography showed 32.1% (0 h) and 32.6% (24 h). 99mTc-GHA study was 90.1% (0 h) to P and 79.9% (24 h), and radioautography showed 67.2% (0 h) and 60.1% (24 h). The binding to BC was 9.9% (0 h) and 20.1% (24 h), and radioautography showed 32.8% (0 h) and 39.9% (24 h). The comparison of the obtained results suggests that the binding to plasma and blood cells in the two techniques used (radioautography and centrifugation) is qualitatively in accordance

Development of finite elements for analysis of biomechanical structures using flexible multibody formulations

The absolute nodal coordinate formulation was originally developed for the analysis of structures undergoing large rotations and deformations. This dissertation proposes several enhancements to the absolute nodal coordinate formulation based finite beam and plate elements. The main scientific contribution of this thesis relies on the development of elements based on the absolute nodal coordinate formulation that do not suffer from commonly known numerical locking phenomena. These elements can be used in the future in a number of practical applications, for example, analysis of biomechanical soft tissues. This study presents several higher-order Euler–Bernoulli beam elements, a simple method to alleviate Poisson’s and transverse shear locking in gradient deficient plate elements, and a nearly locking free gradient deficient plate element. The absolute nodal coordinate formulation based gradient deficient plate elements developed in this dissertation describe most of the common numerical locking phenomena encountered in the formulation of a continuum mechanics based description of elastic energy. Thus, with these fairly straightforwardly formulated elements that are comprised only of the position and transverse direction gradient degrees of freedom, the pathologies and remedies for the numerical locking phenomena are presented in a clear and understandable manner. The analysis of the Euler–Bernoulli beam elements developed in this study show that the choice of higher gradient degrees of freedom as nodal degrees of freedom leads to a smoother strain field. This improves the rate of convergence.

Protection of plasmid DNA by a Ginkgo biloba extract from the effects of stannous chloride and the action on the labeling of blood elements with technetium-99m

Ginkgo biloba extract (EGb) is a phytotherapeutic agent used for the treatment of ischemic and neurological disorders. Because the action of this important extract is not fully known, assays using different biological systems need to be performed. Red blood cells (RBC) are labeled with technetium-99m (Tc-99m) and used in nuclear medicine. The labeling depends on a reducing agent, usually stannous chloride (SnCl2). We assessed the effect of different concentrations of EGb on the labeling of blood constituents with Tc-99m, as sodium pertechnetate (3.7 MBq), and on the mobility of a plasmid DNA treated with SnCl2 (1.2 µg/ml) at room temperature. Blood was incubated with EGb before the addition of SnCl2 and Tc-99m. Plasma (P) and RBC were separated and precipitated with trichloroacetic acid, and soluble (SF-P and SF-RBC) and insoluble (IF-P and IF-RBC) fractions were isolated. The plasmid was incubated with Egb, SnCl2 or EGb plus SnCl2 and agarose gel electrophoresis was performed. The gel was stained with ethidium bromide and the DNA bands were visualized by fluorescence in an ultraviolet transilluminator system. EGb decreased the labeling of RBC, IF-P and IF-RBC. The supercoiled form of the plasmid was modified by treatment with SnCl2 and protected by 40 mg/ml EGb. The effect of EGb on the tested systems may be due to its chelating action with the stannous ions and/or pertechnetate or to the capability to generate reactive oxygen species that could oxidize the stannous ion.