Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Similar understorey structure in spite of edaphic and floristic dissimilarity in Amazonian forests

Forest structure determines light availability for understorey plants. The structure of lowland Amazonian forests is known to vary over long edaphic gradients, but whether more subtle edaphic variation also affects forest structure has not beenresolved. In western Amazonia, the majority of non-flooded forests grow on soils derived either from relatively fertile sediments of the Pebas Formation or from poorer sediments of the Nauta Formation. The objective of this study was to compare structure and light availability in the understorey of forests growing on these two geological formations. We measured canopy openness and tree stem densities in three size classes in northeastern Peru in a total of 275 study points in old-growth terra firme forests representing the two geological formations. We also documented variation in floristic composition (ferns, lycophytes and the palm Iriartea deltoidea) and used Landsat TM satellite image information to model the forest structural and floristic features over a larger area. The floristic compositions of forests on the two formations were clearly different, and this could also be modelled with the satellite imagery. In contrast, the field observations of forest structure gave only a weak indication that forests on the Nauta Formation might be denser than those on the Pebas Formation. The modelling of forest structural features with satellite imagery did not support this result. Our results indicate that the structure of forest understorey varies much less than floristic composition does over the studied edaphic difference.

Taxonomy of the Brazilian firefly Cladodes illigeri (Coleoptera, Lampyridae): morphology and new records

ABSTRACT Cladodes illigeri (Kirby, 1818) is redescribed, and can be distinguished by the following features: color pattern overall black, paired spots and elytral margins pale yellow; pygidium bisinuate, posterior angles rounded, as long as median margin; and aedeagus with phallus 1/3 shorter than the parameres, which are sinuated apically. Cladodes lamellicornis (Motschulsky, 1854) is proposed as a junior synomym of C. illigeri. New records from the Atlantic Rainforest and illustrations for structural features are provided.

Contribuição ao conhecimento da sistemática e biologia de buprestídeos minadores do gênero Pachyschelus Solier, 1833: (Coleoptera, Buprestidae)

Buprestid leaf-miners are generally included in the subtribe Trachytes. The genera belonging to this subtribe are commonly very rich in number of species and their systematics envolves huge difficulties. On the other hand the biological knowledge on those insects is very poor. The A. tries to clarify the systematical status of two species of Pachyschelus - P. subundulatus Kerr. and P. fulgidipennis Lucas, and redescribes also P. binderi Obenberger. The hosts of the first two species are recorded, namely: Terminalia catappa (Combretaceae) - host-plant of P. subundulatus and Luhea spp. (Tiliaceae) - host-plant of P. fulgidipennis. The mines, developmental stages and habits of the three species are described and is made a full redescription of the adults, both male and female. The study is based on reared material from mined leaves, as well as insects assembled in several brazilian collections, both private and public ones. The importance of some biological facts as well as some morphological characters are stressed. The knowledge of the host-plants and the shape and other structural features of the mine were found to be helpfull to the identification of the species. Some morphological features of adults also prooved to be of systematical value. Besides the female pygidium and the male genitalia, the tibiae of the third pair of legs show some intersting structural details, reasonably alike in both sexes and quite different in each species.

Tegumental proteins of Schistosoma mansoni: complex biomolecules and potent antigens

The passive transfer of monoclonal antibodies, direct vaccination and in vitro assays have all shown that antigens associated with the tegumental membranes of Schistosoma mansoni are capable of mediating protective immune responses against the parasite in animal models. Furthermore, the principal antigens are highly antigenic during natural infection in man and stimulate strong humoral and cellular responses although, at present, their role in mediating protective immune responses in man remains equivocal. This presentation will review the current state of knowledge of the structure and expression of the major antigenic tegumental proteins of the schistosome and will attempt to relate the relevance of their structural features to possible function both in terms of protective immunity and parasite's ability to survive within the definitive host. A focus will be recent advances that have been made in the identification of means of anchoring of the antigenic proteins to the tegumental membrane. In addition, the implications of the structural complexity of the tegumental proteins in terms of their possible utility in vaccination and diagnosis will be considered.

Interaction of Diocleinae Lectins with Glycoproteins Based in Surface Plasmon Resonance

Interaction of glucose/mannose-binding lectins in solution with immobilized glycoproteins was followed in real time using surface plasmon resonance technology. The lectins which share many biochemical and structural features could be clearly differentiated in terms of their specificity for complex glycoconjugates. The most prominent interaction of the lectins with PHA-E comparing with soybean agglutinin, both glycoproteins exhibiting high mannose oligosaccharides, suggests that the whole structure of the glycoproteins themselves, may interfere in affinity. These findings also support the hypothesis that minor amino acid replacements in the primary sequence of the lectins might be responsible for their divergence in fine specificity and biological activities. This is the first report using surface plasmon resonance technology that evidences differences of Diocleinae lectins in respect their fine glycan-specificity.

Cytotaxonomy of Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz (Diptera: Simuliidae) in Brazilian Amazonia

Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz are widely distributed in the Amazon region and are morphologically similar at the larval and pupal stages. Chromosomally, these species are readily distinguished by the position of the nucleolar organizer, which is in the short arm of chromosome I in S. cauchense and in the long arm of chromosomes III in S. quadrifidum. They also differ by three fixed inversions. Sex chromosomes are undifferentiated in both species. Chromosomal resolution of the two species allowed us to evaluate four structural features previously used as diagnostic aids at the larval stage. Characters that distinguish larvae of the two species are the number of branches and branching patterns of the dorsal abdominal setae and the dark band on each primary fan. Branching patterns of the gill histoblasts were often diagnostic, with S. quadrifidum exhibiting more proximal branching and S. cauchense more distal branching. Sites where both species occurred sometimes had larvae with one petiole branching proximally and the other distally; in these cases examination of the chromosomes permitted assignment of the specimen to species. Pigmentation patterns of larvae, on the other hand, are highly variable. Color typically is sex linked in both species.

Observations on Eimeria species of Dasyprocta leporina (Linnaeus, 1758)(Rodentia: Dasyproctidae) from the state of Pará, North Brazil

Redescriptions are given of the mature oocysts of Eimeria aguti Carini 1935, E. cotiae Carini, 1935 and E. paraensis Carini, 1935, in the faeces of five specimens of the rodent Dasyprocta leporina (Rodentia: Dasyproctidae) from the state of Pará, North Brazil. New information is provided on the sporulation time of these parasites and the prepatent period in experimentally infected D. leporina. Some endogenous stages of E. cotiae are described in the epithelial cells of the ileum, and the absence of any oocysts in the gall-bladder contents of the infected animals indicates that the intestine is also the site of development of E. aguti and E. paraensis. Difficulties in separating E. cotiae and E. paraensis on morphology of the oocysts are discussed. The oocysts of both parasites share many structural features and have a wide size range. It is concluded that although it is at present best to maintain these names, the possibility exists that they were separately given to oocysts of smaller dimensions (E. cotiae) and larger dimensions (E. paraensis) of a single parasite. Location of an endogenous site of development for E. paraensis that is distinctly separate from that of E. cotiae might establish more definitely the separate specific status of the two parasites.

Brachylophora, a new brachypterous genus of Rhopalophorini (Coleoptera, Cerambycidae)

Brachylophora, a new brachypterous genus of Rhopalophorini (Coleoptera, Cerambycidae). Brachylophora auricollis (Bruch, 1918) comb. nov. = Pasiphyle auricollis Bruch, 1918, originally described from Argentina (Salta), is redescribed and illustrated. Although with reduced elytra, the genus is transferred from Rhinotragini to Rhopalophorini based on the following characters: eyes well separated in both sexes, frons between eyes depressed and lacking frontal suture; pro-, meso-, and metasternum planar; mesothorax parallel-sided, not at all declivous before mesosternal process; metasternum large, together with mesosternum twice length of prosternum, metepisternum very wide, entire suture separating it from metasternum clearly visible when viewed from below; female ovipositor shortened with short cylindrical styles; and, more generally, structural features of hind legs, and surface ornamentation. Habitus similar to Coremia group. Bolivian specimens were netted as they visited flowers of Croton sp. (Euphorbiaceae).

Reações de ozonólise de olefinas em fase gasosa

Biogenic emissions of volatile organic compounds play a fundamental role in the atmospheric chemistry, vegetation being one of their major sources. Amongst the VOCs emitted by plants, olefins and terpenoids are the most abundant. These compounds, due to the presence of two or more double bonds and other structural features, are very reactive in the atmosphere and act as precursors of the photochemical smog and aerosols. This article presents a review of the reactions of olefins and terpenoids with ozone, in the gas phase, with emphasis toward the mechanisms and kinetic aspects.

Lipossomas: a bala mágica acertou?

Efficient drug delivery systems are as important as drug themselves. A powerful drug unable to reach the target cell is useless in practice. Ehrlich's Magic Bullet was the first carrier system to be proposed. The evolution in this domain has been quite slow as the natural mechanisms of mammals against foreign products are hard to overcome. However, lipid-based systems (liposomes and related vesicles) have attained reasonable success. The basic preparations and structural features of liposomes and related vesicles as well as their applications are addressed from the chemist's and biochemist's point of view.

Clerodane diterpenes from leaves of Casearia sylvestris Swartz

Ethanolic extracts of the leaves of Casearia sylvestris yielded a novel clerodane diterpene, 15-hydroxy-3-cleroden-2-one, together with the known diterpenes (-)-hardwickiic acid, reported for the first time from this species, and casearins B and G, previously isolated from C. sylvestris. The structures of all four compounds were determined by spectrometric analysis. The new clerodane diterpene and (-)-hardwickiic acid contain structural features that are completely different from the highly oxygenated casearins and casearvestrins isolated from C. sylvestris.

Proteínas quinases: características estruturais e inibidores químicos

Protein kinases are one of the largest protein families and they are responsible for regulation of a great number of signal transduction pathways in cells, through the phosphorylation of serine, threonine, or tyrosine residues. Deregulation of these enzymes is associated with several diseases including cancer, diabetes and inflammation. For this reason, specific inhibition of tyrosine or serine/threonine kinases may represent an interesting therapeutic approach. The most important types of protein kinases, their structural features and chemical inhibitors are discussed in this paper. Emphasis is given to the small-molecule drugs that target the ATP-binding sites of these enzymes.

Síntese e estudo de ortossilicatos de zinco luminescentes com aplicação da técnica sol-gel

Usually, the concepts of the Sol-Gel technique are not applied in experimental chemistry courses. This work presents a feasible experiment for chemistry instruction, which involves the synthesis of luminescent materials - Zn2SiO4, with and without Mn2+ as a dopant - by the Sol-Gel technique. The obtained materials were analyzed by scanning electron microscopy, X-Ray diffraction, IR spectroscopy and luminescence measures by UV-vis spectroscopy. The results allow the students to confirm the luminescent properties of the zinc orthosilicate luminophores as well as the structural features expected from literature data.

Metabolômica, uma abordagem otimizada para exploração da biodiversidade brasileira: estado da arte, perspectivas e desafios

Brazilian biodiversity is a colossal source of secondary metabolites with remarkable structural features, which are valuable in further biodiscovery studies. In order to fully understand the relations and interactions of a living system with its surroundings, efforts in natural product chemistry are directed toward the challenge of detecting and identifying all the molecular components present in complex samples. It is plausible that this endeavor was born out of recent technological sophistication in secondary metabolite identification with sensitive spectroscopic instruments (MS and NMR) and higher resolving power of chromatographic systems, which allow a decrease in the amount of required sample and time to acquire data. Nevertheless, the escalation of data acquired in these analyses must be sorted with statistical and multi-way tools in order to select key information. Chromatography is also of paramount importance, more so when selected compounds need to be isolated for further investigation. However, in the course of pursuing a "greener" environment, new policies, with an aim to decrease the use of energy and solvents, are being developed and incorporated into analytical methods. Metabolomics could be an effective tool to answer questions on how living organisms in our huge biodiversity work and interact with their surroundings while also being strategic to the development of high value bio-derived products, such as phytotherapeutics and nutraceuticals. The incorporation of proper phytotherapeutics in the so-called Brazilian Unified Health System is considered an important factor for the urgent improvement and expansion of the Brazilian national health system. Furthermore, this approach could have a positive impact on the international interest toward scientific research developed in Brazil as well as the development of high value bio-derived products, which appear as an interesting economic opportunity in national and global markets. Thus, this study attempts to highlight the recent advances in analytical tools used in detection of secondary metabolites, which can be useful as bioproducts. It also emphasizes the potential avenues to be explored in Brazilian biodiversity, known for its rich chemical diversity.