Reproductive biology in the primitive relic Angiosperm Drimys brasiliensis (Winteraceae)

From field observations on Drimys brasiliensis, principally in the Botucatu region of São Paulo State, Brazil, new data on the reproductive biology, the rhythm of growth, and the development of lateral cymose inflorescences, flowers and fruits are presented. Pollination accelerates the rate of flower-development for about 4-6 days. Pollination experiments show that D. brasiliensis is not self-sterile; because of mechanical devices the sticky pollen grains do not normally come into contact with the stigmata unless an animal pollen vector is involved. The pollinators are diurnal Coleoptera, Diptera and Thysanoptera which eat from the pollen, lick from the stigmatic exudates and (in case of the flies) probably also from the staminal glands. Fruit- and seedeaters are birds which seem to be the main dispersal agents. Establishment of new individuals normally is through seedlings, but also by vegetative propagation through plagiotropous branches which may root and separate from the mother plant. The morphological, developmental and reproductive aspects in D. brasiliensis are discussed in a wider context, compared with data from other Magnoliidae, and related to aspects of early Angiosperm evolution. © 1980 Springer-Verlag.

Traços florais e filogenia em espécies lenhosas do cerrado

Pós-graduação em Ciências Biológicas (Botânica) - IBB

Equação de Estado para o Universo Primordial

Pós-graduação em Física - IFT

Dynamical evolution of Saturn's F ring dust particles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

XX : XY sex chromosome system with X heterochromatinization: an early stage of sex chromosome differentiation in the Neotropic electric eel Eigenmannia virescens

An early stage of sex chromosome differentiation is reported to occur in the electric eel Eigenmannia virescens (Pisces, Sternopygidae) from populations of two tributaries of the Parana river system (Brazil). Cytogenetic studies carried out in the two populations showed that the Mogi-Guacu population is characterized by 2n = 38 chromosomes and undifferentiated sex chromosomes and the Tiete population presents 2n = 38 both for males and females and an XX:XY sex chromosome system. The X-chromosome is acrocentric, easily recognized by the presence of a conspicuous heterochromatin block in its distal portion; the Y-chromosome is probably one of the medium sized acrocentrics present in the male karyotype. BrdU induced R-bands of the two populations did not reveal any difference in the euchromatic regions of the chromosomes. AluI and HaeIII restriction enzyme digestion patterns and chromomycin A3 staining of the X-chromosome are presented. The possible role of heterochromatinization in the evolution of sex chromosomes in fish is discussed.

Reproductive morphology of the early-divergent grass Streptochaeta and its bearing on the homologies of the grass spikelet

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Convergent evolution of aposematic coloration in Neotropical poison frogs: a molecular phylogenetic perspective

Poison frogs of the family Dendrobatidae contain cryptic as well as brightly colored, presumably aposematic species. The prevailing phylogenetic hypothesis assumes that the aposematic taxa form a monophyletic group while the cryptic species (Colostethus sensu lato) are basal and paraphyletic. Analysis of 86 dendrobatid sequences of a fragment of the 16S rRNA gene resulted in a much more complex scenario, with several clades that contained aposematic as well as cryptic taxa. Monophyly of the aposematic taxa was significantly rejected by SH-tests in an analysis with additional 12S and 16S rDNA fragments and reduced taxon sampling. The brightly colored Allobates femoralis and A. zaparo (Silverstone) comb. nov. (previously Epipedobates) belong in a clade with cryptic species of Colostethus. Additionally, Colostethus pratti was grouped with Epipedobates, and Colostethus bocagei with Cryptophyllobates. In several cases, the aposematic species have general distributions similar to those of their non-aposematic sister groups, indicating multiple instances of regional radiations in which some taxa independently acquired bright color. From a classificatory point of view, it is relevant that the type species of Minyobates, M. steyermarki, resulted as the sister group of the genus Dendrobates, and that species of Mannophryne and Nephelobates formed monophyletic clades, corroborating the validity of these genera. Leptodactylids of the genera Hylodes and Crossodactylus were not unambiguously identified as the sister group of the Dendrobatidae; these were monophyletic in all analyses and probably originated early in the radiation of Neotropical hyloid frogs.

Biogeography on the early distribution of cuckoos (Aves: Cuculiformes)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Petrological and geochemical evolution of the alkaline Valle Chico Massif, southeastern Uruguay

The Valle Chico Massif is a member of the Early Cretaceous alkaline magmatic suite of rocks distributed around the Parana Basin. Three magmatic associations are recognized: (1) the Plutonic Association, characterized by syenites, quartz syenites, and syenogranites; (2) the Volcanic Association, mainly composed of porphyritic quartz trachytes; and (3) the Porphyritic Dike Association consisting of rhyolites and trachytes. Judging by their geochemical behavior, the rhyolites exhibit a weak peralkaline affinity, and are genetically connected by progressive melting processes, whereas the other lithologies have a metaluminous nature, and are products of mineral fractionation. An enriched mantle of Transamazonian age, geochemically similar to OIB, is postulated as a possible source.

Mesozoic tectonic evolution of the south Orkney microcontinent, Scotia arc, Antarctica

The South Orkney Islands are the exposed part of a continental fragment on the southern limb of the Scotia are. The islands are to a large extent composed of metapelites and metagreywackes of probable Triassic sedimentary age. Deformation related to an accretionary wedge setting, with associated metamorphism from anchizone to the greenschist facies, are of Jurassic age (176-200 Ma). on Powell Island, in the centre of the archipelago, five phases of deformation are recognized. The first three, associated with the main metamorphism, are tentatively correlated with early Jurassic subduction along the Pacific margin of Gondwana. D-4 is a phase of middle to late Jurassic crustal extension associated with uplift. This extension phase may be related to opening of the Rocas Verdes basin in southern Chile, associated with the breakup of Gondwanaland. Upper Jurassic conglomerates cover the metamorphic rocks unconformably. D-5 is a phase of brittle extensional faulting probably associated with Cenozoic opening of the Powell basin west of the archipelago, and with development of the Scotia are.

The use of apatite fission track thermochronology to constrain fault movements and sedimentary basin evolution in northeastern Brazil

An apatite fission track study of crystalline rocks underlying sedimentary basins in northeastern Brazil indicate that crustal blocks that occur on opposite sides of a geological fault experienced different thermal histories. Samples collected on the West block yielded corrected fission-track ages from 140 to 375 Ma, whereas samples collected on the East block yielded ages between 90 and 125 Ma. The thermal models suggest that each block experienced two cooling events separated by a heating event at different times. We concluded that the West block moved downward relative to the East block ca. 140 Ma ago, when sediments eroded from the East side were deposited on the West side. This process represents the early stage of sedimentary basin formation and the opening of the South Atlantic Ocean in the region. Downward and upward movements related to heating and cooling events of these crustal blocks at different periods until recent times are proposed. (c) 2005 Elsevier Ltd. All rights reserved.

Loss of RKIP expression during the carcinogenic evolution of endometrial cancer

Aims Endometrial cancer is one of the most common cancers in women worldwide, but there is a lack of diagnostic markers for early detection of these tumours. The raf kinase inhibitory protein (RKIP) negatively regulates the Raf/MEK/ERK pathway, and the downregulation of RKIP is associated with tumour progression and metastasis in several human neoplasms. The aim of this study was to assess the expression levels of RKIP in endometrial cancer and determine whether this expression correlates with clinical outcome in these patients.Methods Tissue microarrays constructed using tissue samples from 209 endometrial adenocarcinomas, 49 endometrial polyps and 48 endometrial hyperplasias were analysed for RKIP expression by immunohistochemistry.Results The authors found that RKIP expression decreases significantly during malignant progression of endometrial cancer; it is highly expressed in non-neoplastic tissues (polyps 79.6%; hyperplasias 87.5%) and expressed at very low levels in endometrioid adenocarcinomas (29.7%). No correlations were observed between RKIP expression, clinicopathological data and survival.Conclusion This study demonstrated for the first time that RKIP expression is lost during the carcinogenic evolution of endometrial tumours and that the loss of RKIP expression is associated with a malignant phenotype. Functional studies are needed to address the biological role of RKIP downregulation in endometrial cancer.

Pore size evolution during sintering of ceramic oxides

This paper reviews the influence of particle size distribution, agglomerates, rearrangement, sintering atmospheres and impurities on the pore evolution of some commonly studied oxides. These factors largely affect sintering mechanisms due to modifications of diffusion coefficients or evaporation-condensation. Very broad particle size distribution leads to grain growth and agglomerates densify first. Rearrangement of particles due to neck asymmetry mainly in the early stage of sintering is responsible for a high rate of densification in the first minutes of sintering by collapse of large pores. Sintering atmospheres play an important role in both densification and pore evolution. The chemical interaction of water molecules with several oxides like MgO, ZnO and SnO2 largely affects surface diffusion. As a consequence, there is an increase in the rates of pore growth and densification for MgO and ZnO and in the rate of pore growth for SnO2. Carbon dioxide does not affect the rate of sintering of MgO but greatly affects both rates of pore growth and densification of ZnO. Oxygen concentration in the atmosphere can especially affect semiconductor oxides but significantly affects the rate of pore growth of SnO2. Impurities like chlorine ions increase the rate of pore growth in MgO due to evaporation of HCl and Mg(OH)Cl, increasing the rate of densification and particle cuboidization. CuO promotes densification in SnO2, and is more effective in dry air. The rate of densification decrease and pore widening are promoted in argon. An inert atmosphere favors SnO2 evaporation due to reduction of CuO. © 1990.

Karyotype evolution in the Termitidae (Isoptera)

The karyotypes of 15 species of Termitidae were analyzed. All of them are X1X2Y1Y2 (male) and X1X1X2X2 (female). With the exception of Neocapritermes opacus with 2n=40, the remaining species are 2n=42 in both sexes, a karyotype similar to those described for African species by other authors. The sex determining mechanism probably originated before the split up of Gondwanaland, in a single event, early during the karyotype evolution of the family Termitidae by means of a reciprocal translocation that involved the primitive Y and a chromosome from an autosomal pair.