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Search Results: 1 - 10 of 5664 matches for " Leite Vagner Maximino "
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Coffee leaf and stem anatomy under boron deficiency
Rosolem, Ciro Antonio;Leite, Vagner Maximino;
Revista Brasileira de Ciência do Solo , 2007, DOI: 10.1590/S0100-06832007000300007
Abstract: boron deficiency in coffee is widely spread in brazilian plantations, but responses to b fertilizer have been erratic, depending on the year, form and time of application and b source. a better understanding of the effects of b on plant physiology and anatomy is important to establish a rational fertilization program since b translocation within the plant may be affected by plant anatomy. in this experiment, coffee plantlets of two varieties were grown in nutrient solutions with b levels of 0.0 (deficient), 5.0 μm (adequate) and 25.0 μm (high). at the first symptoms of deficiency, leaves were evaluated, the cell walls separated and assessed for b and ca concentrations. scanning electron micrographs were taken of cuts of young leaves and branch tips. the response of both coffee varieties to b was similar and toxicity symptoms were not observed. boron concentrations in the cell walls increased with b solution while ca concentrations were unaffected. the ca/b ratio decreased with the increase of b in the nutrient solution. in deficiency of b, vascular tissues were disorganized and xylem walls thinner. b-deficient leaves had fewer and deformed stomata.
Gibberellin and cytokinin effects on soybean growth
Leite, Vagner Maximino;Rosolem, Ciro Antonio;Rodrigues, Jo?o Domingos;
Scientia Agricola , 2003, DOI: 10.1590/S0103-90162003000300019
Abstract: soybean is an important crop in brazil. nonetheless, there are no reports on the use of plant growth regulator potential in relation to this crop in the national literature. to better understand the role of these compounds, a pot experiment was carried out to study effects of ga3 and cytokinin on the vegetative growth of the soybean. ga3 (50 mg l-1) was applied as seed treatment, leaving plants with water application as control. ga3 (100 mg l-1) and cytokinin (30 mg l-1) were sprayed on leaves at the physiological stage v3/v4, and 15 days after, cytokinin (30 mg l-1), also as foliar spray. seed treatment decreased plant emergence and initial soybean root growth, but as the season progressed, differences in root growth disappeared; plants were shorter, and presented a decrease in the number of nodes, in stem diameter, in leaf area and in dry matter yield. conversely, foliar application of ga3 led to an increase in plant height, first node height and stem diameter. leaf area and dry matter production also increased as a result of ga3 foliar application. there was no effect of exogenous gibberellin and cytokinin on the number of soybean leaves, number of stem branches and root dry matter. joint application of gibberellin and cytokinin tended to inhibit gibberellin effects. cytokinin applied to leaves during soybean vegetative growth was not effective in modifying any of the evaluated plant growth variables.
Gibberellin and cytokinin effects on soybean growth
Leite Vagner Maximino,Rosolem Ciro Antonio,Rodrigues Jo?o Domingos
Scientia Agricola , 2003,
Abstract: Soybean is an important crop in Brazil. Nonetheless, there are no reports on the use of plant growth regulator potential in relation to this crop in the national literature. To better understand the role of these compounds, a pot experiment was carried out to study effects of GA3 and cytokinin on the vegetative growth of the soybean. GA3 (50 mg L-1) was applied as seed treatment, leaving plants with water application as control. GA3 (100 mg L-1) and cytokinin (30 mg L-1) were sprayed on leaves at the physiological stage V3/V4, and 15 days after, cytokinin (30 mg L-1), also as foliar spray. Seed treatment decreased plant emergence and initial soybean root growth, but as the season progressed, differences in root growth disappeared; plants were shorter, and presented a decrease in the number of nodes, in stem diameter, in leaf area and in dry matter yield. Conversely, foliar application of GA3 led to an increase in plant height, first node height and stem diameter. Leaf area and dry matter production also increased as a result of GA3 foliar application. There was no effect of exogenous gibberellin and cytokinin on the number of soybean leaves, number of stem branches and root dry matter. Joint application of gibberellin and cytokinin tended to inhibit gibberellin effects. Cytokinin applied to leaves during soybean vegetative growth was not effective in modifying any of the evaluated plant growth variables.
Putative metabolic pathway of mannitol and sorbitol and in sugarcane
Marino Celso Luís,Leite Susi Meire Maximino,Farro Ana Paula Cazerta,Sassaki Flávio Tetsuo
Scientia Agricola , 2003,
Abstract: Until the mid 1950s, boron was believed to play an important role in the transport of sugars in plants. However, boron actually depends on sugar alcohols to be taken up by the plant. In some cases, the main sugars involved in this process are sorbitol and mannitol which form stable complexes with boron. In this study, the sequences of the SugarCane EST Genome Project (SUCEST) database were searched for enzymes involved in the metabolism of these sugars by comparing them with enzymes from other organisms. Eighteen contigs from sugarcane (Saccharum sp.) presented high similarity with 11 enzymes involved in the putative biosynthetic pathway of sorbitol and mannitol from fructose in sugarcane. Seven of these contigs had high homology with sequences deposited in GenBank.
Abundancia e distribui??o das larvas de peixes no Lago Catal?o e no encontro dos rios Solim?es e Negro, Amazonas, Brasil
Leite, Rosseval Galdino;Silva, José Vagner Valente da;Freitas, Carlos Edwar;
Acta Amazonica , 2006, DOI: 10.1590/S0044-59672006000400018
Abstract: the abundance and monthly distribution of fish larvae in catal?o lake, situated near the confluence of the solim?es and negro river was evaluated between january and may 2001. the samples were obtained using a conical plankton net (350 μm, ? 0.3, 2 m long), with a flow meter attached to the opening of the net. the categorical variables were: position in the lake (margin and center), period of the day (day and night) and depth (surface and bottom). the analysis was made with fatorial correspondence analyses (fca) using the larval density (larvae.m-3) as answer variable and the months as descriptors. the feeding activity of larvae was also studied. most of them were protolarvae feeding in the margin of the lake, on the surface as well as on the bottom. these results indicated that catal?o lake is an important nursery ground for to the larvae of fishes that spawn in the solim?es river.
Boron influence on concentration of polyols and other sugars in Eucalyptus
Leite, Susi Meire Maximino;Valle, Celina Ferraz do;Bonine, César Augusto Valencise;Marino, Celso Luís;
Revista árvore , 2008, DOI: 10.1590/S0100-67622008000500005
Abstract: although the functions of the element boron (b) in plants have not been sufficiently clarified, several hypotheses have been raised. some of the functions attributed to this element are synthesis and transport of carbohydrates. to evaluate the effect of b on the synthesis of some polyols and sugars in eucalyptus grandis and hybrids "urograndis", these species were submitted to situations of supply and restriction of b. the experiment was carried out in a greenhouse, arranged in a randomized block design in a 2 x 2 factorial scheme, with 5 replicates of each genotype. the b levels were provided in the form of nutrient solution. no significant difference was observed in the content of mannitol, sorbitol, myo-inositol and scyllo-inositol and sugars α-glucose and β-glucose between e. grandis and hybrids. arabinose was the only one to present a higher content in e. grandis on restriction of b. the effect of the presence of b was very expressive, but regarding b supply, the plants showed significant increase in the synthesis of the compounds evaluated.
RAPD analysis of genetic variability in a multiprovenance base population of Eucalyptus grandis hill ex maiden
Leite, Susi Meire Maximino;Mori, édson Seizo;Valle, Celina Ferraz do;Bonine, César Augusto Valencise;Marino, Celso Luís;
Revista árvore , 2008, DOI: 10.1590/S0100-67622008000600001
Abstract: this study aimed to evaluate the genetic variability among individuals of a base population of eucalyptus grandis and to build a molecular marker database for the analyzed populations. the eucalyptus grandis base population comprised 327 individuals from coff's harbour, atherton and rio claro. a few plants came from other sites (belthorpe mt. pandanus, kenilworth, yabbra, etc.). since this base population had a heterogeneous composition, the groups were divided according to geographic localization (latitude and longitude), and genetic breeding level. thus, the influence of those two factors (geographic localization and genetic breeding level) on the genetic variability detected was discussed. the rapd technique allowed the evaluation of 70 loci. the binary matrix was used to estimate the genetic similarity among individuals using jaccard's coefficient. parametric statistical tests were used to compare within-group similarity of the means. the obtained results showed that the base population had wide genetic variability and a mean genetic similarity of 0.328. sub-group 3 (wild materials from the atherton region) showed mean genetic similarity of 0.318. s.p.a. (from coff's harbour region) had a mean genetic similarity of 0.322 and was found to be very important for maintenance of variation in the base population. this can be explained since the individuals from those groups accounted for most of the base population (48.3% for it). the base population plants with genetic similarity higher than 0.60 should be phenotypically analyzed again in order to clarify the tendency of genetic variability during breeding programs.
Evolutionary Changes in the Complexity of the Tectum of Nontetrapods: A Cladistic Approach
Caio Maximino
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003582
Abstract: Background The tectum is a structure localized in the roof of the midbrain in vertebrates, and is taken to be highly conserved in evolution. The present article assessed three hypotheses concerning the evolution of lamination and citoarchitecture of the tectum of nontetrapod animals: 1) There is a significant degree of phylogenetic inertia in both traits studied (number of cellular layers and number of cell classes in tectum); 2) Both traits are positively correlated accross evolution after correction for phylogeny; and 3) Different developmental pathways should generate different patterns of lamination and cytoarchitecture. Methodology/Principal Findings The hypotheses were tested using analytical-computational tools for phylogenetic hypothesis testing. Both traits presented a considerably large phylogenetic signal and were positively associated. However, no difference was found between two clades classified as per the general developmental pathways of their brains. Conclusions/Significance The evidence amassed points to more variation in the tectum than would be expected by phylogeny in three species from the taxa analysed; this variation is not better explained by differences in the main course of development, as would be predicted by the developmental clade hypothesis. Those findings shed new light on the evolution of an functionally important structure in nontetrapods, the most basal radiations of vertebrates.
Modulation of nociceptive-like behavior in zebrafish (Danio rerio) by environmental stressors
Maximino, Caio;
Psychology & Neuroscience , 2011, DOI: 10.3922/j.psns.2011.1.017
Abstract: zebrafish have been demonstrated to react consistently to noxious chemical stimuli and present reliable phenotypes of stress, fear, and anxiety. in this article, we describe the modulation of nociceptive-like responses of zebrafish to fear-, stress-, and anxiety-eliciting situations. animals were exposed to an alarm substance, confinement stress, or a novel environment before being injected with 1% acetic acid in the tail. the alarm substance and confinement stress reduced the display of erratic movements and tail-beating behavior elicited by acetic acid. the novelty of the environment, in contrast, increased the frequency of tail-beating behavior. the results suggest that descending modulatory control of nociception exists in zebrafish, with apparent fear- and stress-induced analgesia and anxiety-induced hyperalgesia.
Modulation of nociceptive-like behavior in zebrafsh (Danio rerio) by environmental stressors
Caio Maximino
Psychology & Neuroscience , 2011,
Abstract: Zebrafsh have been demonstrated to react consistently to noxious chemical stimuli and present reliable phenotypes of stress, fear, and anxiety. In this article, we describe the modulation of nociceptive-like responses of zebrafsh to fear-, stress-, and anxiety-eliciting situations. Animals were exposed to an alarm substance, confnement stress, or a novel environment before being injected with 1% acetic acid in the tail. The alarm substance and confnement stress reduced the display of erratic movements and tail-beating behavior elicited by acetic acid. The novelty of the environment, in contrast, increased the frequency of tail-beating behavior. The results suggest that descending modulatory control of nociception exists in zebrafsh, with apparent fear- and stress-induced analgesia and anxiety-induced hyperalgesia.
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