Fractal analysis of leaf-texture properties as a tool for taxonomic and identification purposes: a case study with species from Neotropical Melastomataceae (Miconieae tribe)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sex chromosome evolution in fish: the formation of the neo-Y chromosome in Eigenmannia (Gymnotiformes)

Chromosomes of a species of Eigenmannia presenting a X1X1X2X2:X1X2Y sex chromosome system, resulting from a Y-autosome Robertsonian translocation, were analyzed using the C-banding technique, chromomycin A(3) (CMA(3)) and mithramycin (MM) staining and in situ digestion by the restriction endonuclease AluI. A comparison of the metacentric Y chromosome of males with the corresponding acrocentrics in females indicated that a C-band-positive, CMA(3)/MM-fluorescent and AluI digestion-resistant region had been lost during the process of translocation, resulting in a diminution of heterochromatin in the males. It is hypothesized that the presence of a smaller amount of G+C-rich heterochromatin in the sex chromosomes of the heteromorphic sex when compared with the homomorphic sex may be associated with the sex determination mechanism in this species and may be a more widely occurring phenomenon in fish with differentiated sex chromosomes than was initially thought.

Sugar digestion in mosquitoes: Identification and characterization of three midgut alpha-glucosidases of the neo-tropical malaria vector Anopheles aquasalis (Diptera : Culicidae)

Dietary carbohydrates provide an important source of energy for flight, and contribute to longevity and fecundity of mosquitoes. The most common sugar mosquitoes ingest is sucrose, and digestion of this substance is carried out mainly by alpha-glucosidases. In the current work, we tested the efficiency of sucrose on Anopheles aquasalis female diet. The best longevity (days) was reached when sugar was available in the diet, whereas most only blood fed females were dead 6 days after emergence. Three alpha-glucosidase isoforms were detected in the adult female midgut, named alpha Glu1, alpha Glu2 and alpha Glu3. These are acidic alpha-glucosidases with optima pH around pH 5.5. alpha Glu1 and alpha Glu2 are present in both secreted and membrane-bound forms, whereas alpha Glu3 only in anchored to membranes. The alpha-glucosidase activity is concentrated mainly in the posterior midgut (70%), both in non-fed or 10% sucrose fed females. The single form of these a-glucosidases seemed to be similar to 70 kDa polypeptides, although alpha Glu2 is presented in >= 600 kDa self-aggregates. K, values of alpha Glu1, alpha Glu2 and alpha Glu3 differed significantly from each other, supporting the statement that three alpha-glucosidases are produced in the female midgut. Together, all data suggest that sugar is an essential component of A. aquasalis female diet. In addition, alpha-glucosidases are synthesized in the same place where sucrose is digested and absorbed, the midgut. (c) 2007 Elsevier B.V. All rights reserved.

Nitrogen-tixing and vesicular-arbuscular mycorrhizal symbioses in some tropical legume trees of tribe Mimoseae

Response to mineral fertilization and inoculation with rhizobia and/or arbuscular mycorrhiza fungi (AMF) of the Anadenanthera colubrina, Mimosa bimucronata and Parapiptadenia rigida (Leguminosae-Mimosoideae) native trees from Brazilian riparian forests, were studied in nursery conditions. Each species was submitted to seven treatments, varying nitrogen and phosphorous fertilization and inoculation with rhizobia (r), mycorrhiza (m) or both (rm): NP, P, P + r, P + rm, N, N + m and N + rm. Results showed that AMF inoculations did not enhance the mycorrhizal colonization, and P uptake was not sufficient to sustain good growth of plants. The level of P mineral added affected negatively the AMF colonization in A. colubrina and M. bimucronata, but not in P. rigida. Native fungi infected the three legume hosts. The absence of mineral N limited growth of A. colubrina and P. rigida, but in M. bimucronata the lack of N was corrected by biological nitrogen fixation. N mineral added inhibited the nodulation, although spontaneous nodulation had occurred in A. colubrina and M. bimucronata. Rhizobia inoculation enhanced the number of nodules, nitrogenase activity and leghemoglobin content of these two species. Thus, the extent of rhizobial and mycorrhizal symbiosis in these species under nursery conditions can affect growth and consequently the post-planting success. (C) 2004 Elsevier B.V. All rights reserved.

Phylogeny of Celastraceae Subfamily Salacioideae and Tribe Lophopetaleae Inferred from Morphological Characters and Nuclear and Plastid Genes

The phylogeny of Celastraceae subfamily Salacioideae (ca. 255 species in the Old and New World tropics) and tribe Lophopetaleae (ca. 29 species in southern Asia and the Austral-Pacific) was inferred using morphological characters together with plastid (matK, trnL-F) and nuclear (ITS and 26S rDNA) genes. Brassiantha, a monotypic genus endemic to New Guinea, is inferred to be more closely related to the clade of Dicarpellum (New Caledonia) and Hypsophila (Queensland, Australia) than it is to Hippocrateoideae or Salacioideae. This unambiguously supported resolution indicates that a nectary disk positioned outside the stamens has been convergently derived in these two lineages. The clade of Kokoona and Lophopetalum is resolved as more closely related to Breria and Elaeodendron than it is to Hippocrateoideae or Salacioideae. Sarawakodendron, a monotypic genus endemic to Borneo, is resolved as sister to Salacioideae. Salacioideae are inferred to have an Old World origin that was followed by a single successful radiation within Central and South America. We infer that capsular fruits are primitive within the clade of Hippocrateoideae + Sarawakodendron + Salacioideae, with berries a synapomorphy for Salacioideae. Based on the resolution of Sarawakodendron as sister to Salacioideae, we hypothesize that the filaments of Sarawakodendron arils are homologous to the spiral filaments in the mucilagenous pulp of Salacioideae.

Neo-clerodane diterpenoid, a new metalloprotease snake venom inhibitor from Baccharis trimera (Asteraceae): anti-proteolytic and anti-hemorrhagic properties

Many plants are used in traditional medicine as active agents against various effects induced by snakebite. Few attempts have been made however to identify the nature of plain natural products with anti-ophidian properties. Baccharis trimera (Less) DC (Asteraceae), known in Brazil as carqueja. has been popularly used to treat liver diseases. rheumatism. diabetes, as well as digestive, hepatic and renal disorders. The active component was identified as 7alpha-hydroxy-3,13-clerodadiene-16,15:18,19-diolide, C20H28O5, (clerodane diterpenoid, Bt-CD). We report now the anti-proteolytic and anti-hemorrhagic propenies against snake venoms of a Bt-CD inhibitor from B. trimera. Bt-CD exhibited full inhibition of hemorrhage and proteolytic activity caused by Bothrops snake venoms. The inhibitor was able to neutralize the hemorrhagic, fibrinogenolytic and caseinolytic activities of class P-I and III metalloproteases isolated from B. neuwiedi and B. jararacussu venoms. No inhibition of the coagulant activity was observed. Bt-CD also partially inhibited the edema induced by other crude venoms, metallopronteases, basic and acidic phospholipases A(2). To further elucidate the inhibitory specificity of Bt-CD against metalloproteases isolated from snake venoms, a deeper understanding of its Structure and function is necessary. Furthermore, the potential use of these inhibitors to complement anti-venom as an alternative treatment of snakebite envenomations needs to be evaluated in future Studies. (C) 2004 Elsevier B.V.. All rights reserved.

Comparative study of the fat body in some genera of the attini tribe (Hymenoptera: Formicidae)

The Cyphomyrmex rimosus Spinola and Mycetarotes parallelus Emery species of ants, considered basal, and Acromyrmex disciger Mayr and Atta laevigata Smith, considered derived, have fat bodies specially distributed on their gaster, around their organs and right below the cuticle. The fat body is formed by trophocytes, which are characterized by their pronounced vacuolization of the cytoplasm and the irregular morphology of their nuclei caused by the pressure exerted by cytoplasmic vacuoles. In C. rimosus, the nuclei are more regular, presenting an oval or a star form. In A. disciger and A. laevigata the nuclei present chromatin in a cord form, while in C. rimosus and M. paralellus the chromatin is uniformly distributed in the nucleoplasm, very condensed in the latter species. The parietal trophocytes of A. disciger show cytoplasm with a smaller quantity and smaller sizes of vacuoles compared to ones from the perivisceral region, the opposite is observed in C. rimosus. In A. laevigata and M. parallelus there were no differences observed in their cytoplasm between both regions of cells. In the trophocytes of C. rimosus, A. disciger, A. laevigata, there was a reticular aspect of the cytoplasm observed in the region between vacuoles, not seen on M. parallelus. Another cellular type, oenocyte, was found associated with the fat body cells, and is dispersed between trophocytes with an inner contact to them, but no membrane fusion with them. The oenocytes have a spherical form and are smaller than the trophocytes; they have acidophilic cytoplasm with a small quantity of small vacuoles, and round nuclei.

Comparative study of the histology, histochemistry and ultramorphology of the proventriculus in the cephalotini tribe (Hymenoptera: Formicidae)

The use of optical microscopy and scanning electron microscopy propitiated the comparative examination of the nature of the histology, histochemistry and ultramorphology of the proventriculus bulb of Cephalotes atratus, C. clypeatus and C. pusillus. This portion of the digestive tract possesses highly sclerotized cuticular projections which act in the selection of victuals. A layer of amorphous material with mucous characteristics is present over the cuticle projections. That layer seems to optimize the efficiency of the proventriculus in the selection of food for social function in the colony (trophallaxis). More details of the characteristics of this structure are described in this study.

Karyotype analysis of seven species of the tribe lophiohylini (Hylinae, Hylidae, Anura), with conventional and molecular cytogenetic techniques

Few species of the tribe Lophiohylini have been karyotyped so far, and earlier analyses were performed mainly with standard staining. Based on the analysis of seven species with use of routine banding and molecular cytogenetic techniques, the karyotypes were compared and the cytogenetic data were evaluated in the light of the current phylogenies. A karyotype with 2n = 24 and NOR in the chromosome 10 detected by Ag-impregnation and FISH with an rDNA probe was shared by Aparasphenodon bokermanni Miranda-Ribeiro, 1920, Itapotihyla langsdorffii (Duméril and Bibron, 1841), Trachycephalus sp., T. mesophaeus (Hensel, 1867), and T. typhonius (Linnaeus, 1758). Phyllodytes edelmoi Peixoto, Caramaschi et Freire, 2003 and P. luteolus (Wied-Neuwied, 1824) had reduced the diploid number from 2n = 24 to 2n = 22 with one of the small-sized pairs clearly missing, and NOR in the large chromosome 2, but the karyotypes were distinct regarding the morphology of chromosome pairs 4 and 6. Based on the cytogenetic and phylogenetic data, it was presumed that the chromosome evolution occurred from an ancestral type with 2n = 24, in which a small chromosome had been translocated to one or more unidentified chromosomes. Whichever hypothesis is more probable, other rearrangements should have occurred later, to explain the karyotype differences between the two species of Phyllodytes Wagler, 1830. The majority of the species presented a small amount of centromeric C-banded heterochromatin and these regions were GC-rich. The FISH technique using a telomeric probe identified the chromosome ends and possibly (TTAGGG)n-like sequences in the repetitive DNA out of the telomeres in I. langsdorffii and P. edelmoi. The data herein obtained represent an important contribution for characterizing the karyotype variability within the tribe Lophiohylini scarcely analysed so far. © Simone Lilian Gruber et al.

An outline of a neo-structuralist approach

Presenta un contrapunto de los enfoques neoliberal y neoestructuralista, tanto en su dimension teorica como en su aplicacion al diseno de politicas publicas.

Neo-liberalism versus neo-structuralism in Latin America

Includes bibliography

Neo-Keynesian macroeconomics as seen from the South

Includes bibliography

Neo-structuralism versus neo-liberalism in the 1990s

Presenta un contrapunto crítico en torno a los aspectos más fundamentales que distinguen a las actuales propuestas estratégicas de desarrollo de largo plazo asociadas a los enfoques neoliberal y neoestructuralista.

Neo-liberal structural reforms in Latin America: the current situation

Includes bibliography