864 resultados para Plant biology|Genetics|Evolution and Development
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The Malpighian tubules of Aedes aegypti showed significant differences in their diameters between male and female larvae, male and female pupae, male larvae and male adults and male pupae and male adults. in every case, female values were greater than in males. Measurements of mean nuclear areas of the principal and stellate cells from Malpighian tubules, taken in males and females during development, showed that this parameter in both types of cell was significantly greater in females than in male larvae, pupae and adult stages. In males, significant differences between developmental stages were observed only in comparison with the nuclear area of larvae and adults in the principal cells, but in females, every comparison between stages showed significant differences except between pupae and adults in stellate cells. The frequency distribution of nuclear area values, in development, for male stellate and principal cells, were mostly concentrated in the first seven classes among the 30 classes considered in every stage, while for females, the frequency dropped drastically in the same classes from larvae to pupae and adults, moving to classes of higher values. Considering the importance of Malpighian tubules in insect physiology, the meaning of the differences detected are discussed on the basis of different metabolic levels, between sexes and developmental stages.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In recent years, studies based on isoenzymatic patterns of geographic variation have revealed that what is usually called the Africanized honey bee does not constitute a single population. Instead, several local populations exist with various degrees of admixture with European honey bees. In this paper, we evaluated new data on morphometric patterns of Africanized honey bees collected at 42 localities in Brazil, using univariate and multivariate (canonical) trend surface and spatial autocorrelation analyses. The clinal patterns of variation found for genetically independent characters (wing size characters and some wing venation angles) are concordant with previous studies of malate dehydrogenase (MDH) allelic frequencies and support the hypothesis that larger honey bees in southern and southeastern Brazil originated by racial admixture in the initial phases of African honey bee colonization. Geographic variation patterns of Africanized honey bee populations reflect a demic diffusion process in which European genes were gradually lost because of the higher fitness of the African gene pool in Neotropical environmental conditions.
Sequence, evolution and ligand binding properties of mammalian Duffy antigen/receptor for chemokines
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The Duffy antigen/receptor for chemokine, DARC, acts as a widely expressed promiscuous chemokine receptor and as the erythrocyte receptor for Plasmodium vivax. To gain insight into the evolution and structure/function relations of DARC, we analyzed the binding of anti-human Fy monoclonal antibodies (mAbs) and human chemokines to red blood cells (RBCs) from 11 nonhuman primates and two nonprimate mammals, and we elucidated the structures of the DARC genes from gorilla, gibbon, baboon, marmoset, tamarin, night monkey and cattle. CXCL-8 and CCL-5 chemokine binding analysis indicated that the promiscuous binding profile characteristic of DARC is conserved across species. Among three mAbs that detected the Fy6 epitope by flow cytometric analysis of human and chimpanzee RBCs, only one reacted with night monkey and squirrel monkey. Only chimpanzee RBCs bound a significant amount of the anti-Fy3 mAb. Fy3 was also poorly detected on RBCs from gorilla, baboon and rhesus monkey, but not from new world monkeys. Alignment of DARC homologous sequences allowed us to construct a phylogenetic tree in which all branchings were in accordance with current knowledge of primate phylogeny. Although DARC was expected to be under strong internal and external selection pressure, in order to maintain chemokine binding and avoid Plasmodium vivax binding, respectively, our present study did not provide arguments in favor of a selection pressure on the extracellular domains involved in ligand specificity. The amino acid variability of DARC-like polypeptides was found to be well correlated with the hydrophylicity indexes, with the highest divergence on the amino-terminal extracellular domain. Analysis of the deduced amino acid sequences highlighted the conservation of some amino acid residues, which should prove to be critical for the structural and functional properties of DARC.
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'Brasilia' is a cultivar of carrot with characteristics suiting cultivation under hot conditions but with problems in seed production, arising from the conflicting requirements of root and seed production. One solution is to select cultivars requiring vernalisation and then to use GA(3) to induce flowering where the climate prevents this. There is, however, little information on plant population, seed maturity and harvesting time on which to base such a procedure. Accordingly this research was carried out to study the physiological quality and production of the seeds in plant populations from 25,000 to 800,000 plants/ha, in the seed-to-seed method of cv. Brasilia in Anapolis, GO, Brazil. In each population, two harvest methods (from first and second orders of umbels, or selected harvest, and remaining orders, or total harvest) and two stages of maturity (brownish, or mature seeds, and yellowish, or immature ones) were also evaluated. Two trials were carried out, with and without gibberellic acid. Seed was evaluated for physical characters, germination, vigour, 1000-seed weight, water content, dry matter and productivity. Seed was produced in both experiments (with or without GA3 spraying). Mature seed showed germination at least 30% greater than immature, and seed from the selected harvest showed germination 16% greater than from the total harvest. In increasing plant population to 200,000 plants/ha, seed quality was not affected, but productivity increased.
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Usability evaluation (UE) methods may have several purposes: identify and diagnose usability problems; evaluate the implementation, comparing the one under evaluation with other systems, and also perform acceptance test. These methods are usually expensive, time-consuming and complex. In this context, the ErgoCoIn 1.0 has being used as an accessible system that can be used by several people all over the world, even if they are not usability experts or evaluators. This paper aims to present a new version of this environment considering that its basic objective is to propose a higher quality for the questions. Additionally, a new presentation questionnaire window small enough to be used both in web browsers and mobile devices is proposed.
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Bioactivity-guided fractionation of several bioactive extracts obtained from Cerrado and Atlantic Forest plant species led to the isolation of potent DNA-damaging piperidine 1-5 and guanidine alkaloids 6-9 from Cassia leptophylla and Pterogyne nitens respectively, two common Leguminosae from Atlantic Forest. By means of biotechnological approach on Maytenus aquifolium, a species from Cerrado, moderate DNA-damaging sesquiterpene pyridine alkaloid 10-11 was isolated. Bioassay-guided fractionation on Casearia sylvestris, a medicinal plant species found in Cerrado and Atlantic Forest, led to the isolation of clerodane diterpenes 12-13 which showed effect on DNA. In addition, we have reported several interesting potent antifungal iridoids: 1β-hydroxy-dihydrocornin (14), 1α-hydroxy-dihydrocornin (15), α-gardiol (16), β-gardiol (17), plumericin (18), isoplumericin (19), 11-O-trans-caffeoylteucrein (20); ester derivative: 2-methyl-4-hydroxy-butyl-caffeoate (21), amide N-[7-(3'.4'-methylenedioxyphenyl)-2Z, 4Z-heptadienoyl] pyrrolidine (22) and triterpene viburgenin (23).
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Ovule structure and development are described for twelve species of Bromeliaceae, representing ten genera and all three subfamilies, including all three tribes of the polyphyletic subfamily Pitcairnioideae (Brocchinieae, Puyeae and Pitcairnieae). The characteristic micropylar and chalazal seed appendages of Bromeliaceae are compared with developing structures in the ovules. Chalazal seed appendages have also been reported in the putatively related family Rapateaceae, but they differ in detailed structure, and may have evolved independently in the two families.
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