Substâncias fenólicas, flavonoides e capacidade antioxidante em erveiras sob diferentes coberturas do solo e sombreamentos / Phenolic Substances, Flavonoids, and Antioxidant Capacity in Herbs under Different Soil Covers and Shadings

RESUMO Objetivou neste trabalho analisar a concentração de polifenóis totais, flavonoides e capacidade antioxidantes por meio dos métodos ABTS e FRAP, em erveiras jovens cultivadas em solo coberto e com sombreamento. Mudas de erva-mate foram submetidas aos tratamentos com solos cobertos e desnudos em sombreamentos de 0, 18, 35 e 50%, após sete e onze meses de cultivo, verão e outono, respectivamente. Foram coletadas folhas maduras para realização dos extratos utilizados para as análises de compostos fenólicos por meio da reação de oxirredução com reagente de Folin-Ciocalteu, flavonoides por método colorimétrico e capacidade antioxidante por frente ao radical ABTS e poder de redução do ferro (FRAP). O teor de compostos fenólicos foi maior nos tratamentos com 35% de sombreamento em comparação ao grupo dos flavonoides e capacidade antioxidante, o que foi demonstrado pela correlação do sombreamento com estes parametros. No método FRAP a maior correlação demonstra que o outono é a melhor época de colheita por apresentar maior concentração de compostos fitoquímicos. Ficou evidente a influência positiva dos sombreamentos (35 e 50%) no teor de compostos fenólicos e flavonoides relacionados à capacidade antioxidante e à qualidade da erva-mate para atender ao mercado consumidor.

ABSTRACT This study aimed to analyze the concentration of total polyphenols, flavonoids, and antioxidant capacity, by the methods ABTS and FRAP, in young herbs grown in covered and shaded soil. Yerba mate seedlings were subjected to treatment with bare and covered soils in shadings of 0, 18, 35, and 50%, after seven and eleven months cultivation, summer and fall, respectively. Mature leaves were collected to perform the analyses of phenolic compounds by redox reaction with Folin-Ciocalteu reagent, of flavonoids by colorimetric method, and of antioxidant capacity by ABTS radical and FRAP (iron reduction method). The content of phenolic compounds was higher in the treatments with 35% shading in correlation with the group of flavonoids and antioxidant capacity. In the FRAP method, the higher correlation shows that autumn is the best time to harvest because of the higher concentration of phytochemical compounds. The positive influence of shading (35 and 50%) was evident in the content of phenolic compounds and flavonoids related to antioxidant capacity and better quality of yerba mate to meet the consumer market.

Morphology, ecophysiology and germination of seeds of the Neotropical tree Alibertia patinoi (Rubiaceae) / Morfología, ecofisiología y germinación de semillas del árbol neotropical

Alibertia patinoi (Rubiaceae). Alibertia patinoi (Rubiaceae) is of economic and cultural importance for communities in the Colombian Pacific and Amazon regions, where it is cultivated and mature fruits are highly appreciated and consumed. Since there is a lack of knowledge of the seed physiology of this species, we describe here the germination behavior and morphometry of seeds of Alibertia patinoi, and relate them to its habitat. Fruits were collected from a mixed food crop and a commercial plantation in Guaimía village, Buenaventura, Colombia, a tropical rain forest area. We measured length, width, thickness, mass (n=1 400), and moisture content of seeds (n=252). Primary dormancy tests were conducted (n=200), followed by imbibition (n=252) and germination dynamics, under different conditions of light and temperature specific to understory and forest clearings (n=300 seeds). Finally, seed storage behavior was established (n=100 seeds). We observed that size and mass of seeds had a narrow range of values that did not differ within or among fruits and that the species did not exhibit primary dormancy. The seeds are recalcitrant, and recently harvested seeds exhibited higher seed moisture content (ca. 44%) and continuous metabolism. The seed germination percentage was observed to be higher under the specific dense canopy forest light and temperature conditions; furthermore, neither enriched far-red light nor darkness conditions inhibited germination. We concluded that rapid germination could be the establishment strategy of this species. Also, the physiological traits (i.e., rapid germination rate, low germination requirements, absence of primary dormancy, and recalcitrant behavior) and seed size and mass, suggest that A. patinoi is adapted to conditions of mature tropical rain forests.

La germinación y morfometría de las semillas de Alibertia patinoi se describen y se relacionan con el hábitat de la especie, el Bosque Pluvial Tropical Americano. Se midió la longitud, ancho, grosor, peso y contenido de humedad de las semillas. Se realizaron pruebas de latencia, imbibición y dinámica de la germinación con diferentes condiciones de luz y temperatura específicas de claros y de sotobosque cubierto por un dosel denso. Además, se estableció el comportamiento de almacenamiento de las semillas. El tamaño y peso de las semillas no difieren dentro ni entre frutos. Las semillas recién cosechadas no tienen latencia primaria, presentan alto contenido de humedad (ca. 44%), metabolismo continuo y son recalcitrantes. La germinación tuvo porcentajes altos y en condiciones de luz y temperatura específicas de bosque con follaje denso, y ni la luz enriquecida con rojo lejano ni la oscuridad inhibieron la germinación. Se concluye que la germinación rápida podría ser la estrategia de establecimiento de esta especie. Además, los rasgos fisiológicos, el tamaño y peso de las semillas, sugieren que A. patinoi está adaptada a las condiciones del bosque lluvioso tropical maduro y se comporta como una especie que no es pionera.

Effect of thyroid stimulating hormone on the ultrastructure of the thyroid gland in the Mexican axolotl during metamorphic climax.

Anuran metamorphosis has long-served as a model of how thyroid hormones regulate post-embryonic development in vertebrates. However, comparatively little is known about urodele metamorphosis. Twofold approach was utilized in the present study including induction of metamorphosis in the obligatory neotenic Mexican axolotl (Ambystoma mexicanum) by applying thyroid stimulating hormone (TSH) treatment and investigating the alternations in the ultrastructure of the thyroid gland that occur during metamorphic climax. The results highlighted the difficulty of inducing metamorphosis in this obligatory neotenic urodele animal and indicated that there are huge variations in the response of experiment animals to the TSH treatment which ranged from complete insensitivity to death. During metamorphic climax induced by TSH treatment, the thyroid follicular cells exhibited evident signs of activation compared with both non-metamorphosed and control animals. These signs include the presence of abundant stacks of rough endoplasmic reticulum on the basement membrane side of the cell, large amount of Golgi complexes, intracellular droplets, dense lysosomal like vacuoles, mitochondria and free ribosomes are observed in the cytoplasm. Colloid vesicles and clear vesicles were also observed in the cytoplasm indicating the production of thyroid hormone.

Características básicas para um agrupamento ecológico preliminar de espécies madeireiras da floresta de terra firme da Amazônia Central / Basic characteristics for a preliminary ecological ranking of timber species occurring in a non-flooded forest in Central Amazonia

O objetivo deste trabalho foi reunir informações sobre espécies madeireiras de terra firme nas proximidades de Manaus e tentar identificar as suas possíveis posições no contexto da sucessão florestal. Uma classificação facilitará modelar a dinâmica da floresta para apoiar a conservação, o manejo florestal e a reabilitação de áreas degradadas. O grupo estudado foi formado por 60 espécies botânicas pertencentes a 42 gêneros e 18 famílias. Em uma visão geral observaram-se sementes grandes >0,5cm3 (69 por cento das espécies estudadas), predominância da dispersão zoocórica (60 por cento), germinação em um período de até três meses (69 por cento) e densidade elevada da madeira (>0,8g/cm3 em 52 por cento). O conjunto das características utilizadas não foi adequado para classificar todas as espécies, pois características consideradas como típicas para pioneiras, ou clímax, foram observadas na mesma espécie em 24 das árvores selecionadas (40 por cento). A densidade da madeira e a regularidade de frutificação apresentaram pouca utilidade na classificação, como também a presença de dormência nas sementes, pois há dormência em espécies de todas as fases sucessionais. Porém, a distinção entre os diversos tipos de dormência permitiu a separação dos grupos. Sugerem-se, para uma classificação mais robusta, os seguintes critérios ligados a semente: tipo de dispersão, quantidade das reservas, tolerância ao dessecamento e tipo de dormência. A tentativa de classificação das espécies madeireiras evidenciou que a maioria apresentou o conjunto das características típicas do estádio final da sucessão florestal. Porém, poucas apresentaram características de estádios mais iniciais da sucessão, e possuem provavelmente maior resistência às perturbações florestais.

The aim of this study was to gather information on timber trees occurring in a non-flooded forest near Manaus and to make an attempt to rank these species according to their succession in the forest. The ranking would be helpful in modeling the forest's dynamics, for forest conservation, management and rehabilitation of degraded areas. The group studied was formed by 60 botanical species belonging to 42 genera and 18 families. In a general view, seed size was >0.5cm3 (69 percent of the species), seed dispersal by animals predominated (60 percent), germination occurred within a period of up to 3 months (69 percent) and wood density was high (>0.8 g/cm3 in 52 percent). However the set of characteristics did not permit a clear ranking of all species, as characteristics thought to be typical for pioneer or climax occurred together on the same species in 24 of the selected trees (40 percent). Wood density and fruiting regularity showed to be of little use for classification, as well as the presence of seed dormancy, as dormancy was detected in all successional groups. On the other hand, a distinction between the various types of seed dormancy was helpful to separate the groups. The following seed related characteristics may be recommended for classification: dispersal type, reserve quantity, desiccation tolerance and dormancy types. The attempt of ranking the timber species according to their role in natural succession showed that most had a set of characteristics typical of mature forest. Only a few species had earlier successional characteristics, and probably have higher resistance to forest disturbance.