Desenvolvimento de Maytenus ilicifolia e de seus polifenóis totais sob condição de sombreamento e poda / Shadowing and pruning on the development and polyphenol contents in Maytenus ilicifolia

Maytenus ilicifolia Mart. ex Reissek (Celastraceae), conhecida popularmente por espinheira-santa, é nativa e cultivada, principalmente, no sul do Brasil. Suas folhas apresentam triterpenos e substâncias polifenólicas (flavonóides e taninos) relacionadas ao efeito antiulcerogênico. O objetivo do trabalho foi avaliar a produção de massa seca, altura, ramificação, e o teor de polifenóis totais em plantas de M. ilicifolia que se desenvolveram sob duas condições de luminosidade, após dois tratamentos distintos de poda. O delineamento experimental foi em blocos cazualizados com plantas desenvolvidas sob sombra e a pleno sol, e com plantas manejadas por poda parcial e rasa, com quatro repetições. No tratamento de poda rasa a maior altura das plantas foi observada nas plantas cultivadas a sombra em comparação com as conduzidas a pleno sol. No tratamento de poda parcial o número de ramos terciários aumentou significativamente nas plantas conduzidas a pleno sol. As plantas cultivadas a pleno sol apresentaram diferença significativa na concentração de polifenóis totais em relação às plantas produzidas à sombra alcançando valores de 10,29 ± 0,20% (CV=1,94%) e 7,16 ± 0,09% (CV=1,30%) respectivamente.

The Maytenus ilicifolia Mart. ex Reissek (Celastraceae), traditionally known as "espinheira-santa" in Portuguese, is native and cultivated in South Brazil. Its leaves contain triterpenes and polyphenolic compounds (flavonoids and tannins), which are related to the antiulcerogenic effect. The aim of this work was to evaluate the dried biomass production (g), height (m), ramification, and also the total content in polyphenol compounds of the leaves from the M. ilicifolia specie, which were developed under two different light conditions after two different pruning treatments. The design of the experiment was randomized blocks with two levels of light (shadow or full sunlight) and two levels of prune (partial and drastic), with four replications. The height of the plants grown in the shadow was greater for the treatment of drastic pruning than in plants in full sunlight. The ramification increased significantly with drastic prune in full sunlight. The plants grown in full sunlight showed a significant higher content in total polyphenols than the plants grown in the shadow, 10.29±0.20% (RSD=1.94%) and 7.16±0.09% (RSD=1.30%) respectively.

Nano-structure of the laminin γ-1 short arm reveals an extended and curved multidomain assembly.

Laminins are multidomain glycoproteins that play important roles in development and maintenance of the extracellular matrix via their numerous interactions with other proteins. Several receptors for the laminin short arms revealed their importance in network formation and intercellular signaling. However, both the detailed structure of the laminin γ-1 short arm and its organization within the complexes is poorly understood due to the complexity of the molecule and the lack of a high-resolution structure. The presented data provide the first subatomic resolution structure for the laminin γ-1 short arm in solution. This was achieved using an integrated approach that combined a number of complementary biophysical techniques such as small angle X-ray scattering (SAXS), analytical ultracentrifugation, dynamic light scattering and electron microscopy. As a result of this study, we have obtained a significantly improved model for the laminin γ-1 short arm that represents a major step forward in molecular understanding of laminin-mediated complex formations.

Cuticular Architecture of Hassalstrongylus epsilon (Nematoda: Trichostrongyloidea).

Hassalstrongylus epsilon is a small nematode, whose adult forms are found among the intestinal microvilli of the water rat Nectomys squamipes, Brants 1827 (Rodentia: Muridae). The external appearance of the cuticle, which presents transversal striations and longitudinal ridges, is described using scanning electron microscopy. Transmission electron microscopy of thin sections and replicas of quick-frozen, freeze-fractured, deep-etched and rotatory shadowed samples showed the presence in the cuticle of struts that arise from the fluid median layer, extending outward to the epicuticle. The cuticle showed the presence of five layers: epicuticle, cortical, fibril-rich, fluid median and fibrous. The cuticle layers were made of an assemblage of fibers that create compartments, which were larger in the fluid region than in the fibril-rich median layer.

Rotary and unidirectional metal shadowing of VAT: localization of the substrate-binding domain.

AAA-ATPases have important roles in manifold cellular processes. VAT (valosine-containing protein-like ATPase of Thermoplasma acidophilum), a hexameric archaeal member of this family, has the tripartite domain structure N-D1-D2 that is characteristic of many members of this family. N, the N-terminal domain of 20.5 kDa, has been implicated in substrate binding. We have applied rotary and unidirectional shadowing to VAT and an N-terminally deleted mutant, VAT(Delta N), in order to map the location of this domain. For the analysis of data derived from unidirectionally shadowed samples we used a new approach combining eigenvector analysis with surface relief reconstruction. Averages of rotary shadowed particles as well as relief reconstructions map the N-terminal domains to the periphery of the hexameric complex and reveal their bipartite structure. Thus, this method appears to be well suited to study the conformational changes that occur during the functional cycle of the protein.

A simple method of chromium coating using a ferrotype plate for scanning electron microscopy.

A simple method of chromium coating was developed. A chromium ferrotype plate for drying photoprints was used as a target of a planar magnetron ion-sputter coater. As a result, a high quality chromium film was obtained on dried specimens at room temperature without cooling. The grain size, measuring 1-2 nm in diameter, was small enough for observations of ultrastructures such as F1 particles on the inner mitochondrial membrane. In routine studies under x 100,000, however, chromium coating was not recommended because of its low emission of secondary electrons.