Ruy Carvalho

Low molecular weight protein tyrosine phosphatase genetic polymorphism and susceptibility to cancer development

Low molecular weight protein tyrosine phosphatases (LMW-PTPs) are a family of 18-kDa enzymes involved in cell growth regulation. Human acid phosphatase 1 (ACP1) is genetically polymorphic, and three common alleles segregating at the ACP1 locus on the short arm of chromosome 2 give rise to six phenotypes. Each allele appears to encode two electrophoretically different isozymes, fast and slow, which are produced in allele-specific ratios. Fast isozymes are related with cytoskeletal organization, cellular organization, and spreading. Slow isozymes are associated with growth factor receptors and dephosphorylation. In this study, ACP1 genetic polymorphisms were determined by polymerase chain reaction-restriction fragment length polymorphism on 74 subjects with various cancers; the control group was 236 healthy subjects randomly selected. With genotypes cumulated according to fast isoform concentration, [A + AC] < [AB + BC] < [BB], subjects with cancer presented an increase of fast isozyme concentration (BB 38.2%; P = 0.002, chi2), relative to the control sample (19.8%). The increase of fast isozyme concentration increased the invasive capacity of cancer cells, whereas a decrease of slow isozyme concentration in cancer did not cause growth inhibition and so resulted in cancer cell proliferation.

Relação entre atributos físicos, mineralogia da fração argila e formas de alumínio no solo

Aluminum (Al) is one of the most abundant elements in weight in Brazilian soils, found in different minerals and forms. Considering the lack of information about its participation in the physical behavior of soil, the present study aimed to evaluate the relationship between the mineralogy of the clay fraction, different forms of Al and physical attributes of different soils. Disturbed and undisturbed samples of A and B horizons of representative soils from the South and Campos das Vertentes physiographic regions in the State of Minas Gerais were therefore collected. The samples were subjected to physical, chemical and mineralogical characterizations. Correlation studies performed with the resulting data from the different characterizations showed that the physical attributes of the different studied soils are associated to the different forms of Al and to the mineralogy of the clay fraction: the amorphous and less crystalline forms of Al were more associated to physical attributes related with particle aggregation, such association being ascribed to the affinity of this element with organic matter, while the crystalline components were more associated to physical attributes related with the structural organization of the soils.

Dessorção de fósforo por silício em solos cultivados com eucalipto

With the objective to evaluate the desorption of phosphorus by silicon in surface layers of a Dark-Red Latosol (Oxisol) under cerrado vegetation and Cambisol (Inceptisol), under open cerrado vegetation at Campos das Vertentes physiographical region State Minas Gerais, experiments were carried out under greenhouse conditions at the Soil Science Department of the Federal University of Lavras, Minas Gerais state, Brazil, from August 1997 to May 1998. Each soil was submitted to three sequential incubations: (a) CaCO3 + MgCO3 to maintain the pH around 6.0; (b) basic fertilization, including phosphorus in one dose calculated to maintain 0.2 mg L-1 of P in soil solution; and (c) six silicon (CaSiO3) doses defined with basis on phosphorus dose. Seedlings of Eucalyptus grandis were cultivated during 120 days in pots with 3 dm3 of soil. Dry matter production and dry matter P content were evaluated at 60, 90 and 120 days after seedling transplanting to the pots. Response surfaces of these variables were adjusted as a function of Si doses and times. The desorbed P contributed with 15.25% of the content of this nutrient in dry matter of plants cultivated in the Cambisol (higher content of kaolinite).

Lycopersicon esculentum submitted to Cd-stressful conditions in nutrition solution: Nutrient contents and translocation.

The increasing number of cases on soil contamination by heavy metals has affected crop yields, besides representing an imminent risk to food. Some of these contaminants, such as cadmium, are very similar to micronutrients and thus more easily absorbed by the plants. This study assessed the effect of increasing amounts of cadmium on the content and translocation of micro and macronutrients in tomato. Tomatoes were grown in Clarks nutrient solution and subjected to increasing levels of Cd: 0, 0.025, 0.1, 0.5 and 1.0mg L(-1). The plants contaminated by cadmium had a maximum reduction in the aerial part compared to the control of: 2.25g kg(-1), 2.80g kg(-1), 18.93mg kg(-1) and 14.15mg kg(-1) for K, Ca, Mn and Zn, respectively. In other parts of the tomato were reduced from 2.3g kg(-1) K in fruits and 280.5mg kg(-1) of Mn in the roots. In addition to changes in the levels of some nutrients, the restricted Cd translocation in 1.15 percent P and 2.8 percent Cu to shoots compared to control, but did not affect the translocation of K, Ca, Mg and Zn.

Estudo dos efeitos do silício e do fósforo na redução da disponibilidade de metais pesados em área de mineração

This study was developed with a soil contaminated by heavy metals, with the purpose of evaluating the action of silicon and phosphorus as protection agents through simple extractions by DTPA. The collected samples were prepared and incubated with five doses of silicon and five doses of phosphorus, with four replicates, amounting to 100 experimental units. After 30 and 60 days, samples of each treatment were collected, submitted to pH analyses and simple extraction by DTPA. The amounts of DTPA-extracted metals depended on the doses of silicon and phosphorus and on the pH. Treatments with silicon and phosphorus was efficient in decreasing the availability of heavy metals in soil.

Produção de matéria seca e de grãos por plantas de feijoeiro (Phaseolus vulgaris L.) cultivadas em solos tratados com metais pesados

This work aimed at evaluating the contents of extractable Cd, Pb, Zn and Cu with a solution of DTPA (diethyleneaminopentacetic acid) and to relate them with the production of dry material and grain production of bean plants under two conditions of experimentally contaminated soil materials with Cd, Pb, Cu and Zn: (i) samples of distrofic red latosol and (ii) humic yellow-red latosol. A decrease in the yield of dry matter was observed for all treatments, if compared with the zero-dose control sample; the grain yield was affected for the soil samples treated with Cd and Cu but only slightly for those treated with Pb and Zn.

Theoretical spectroscopic studies and identification of metal-citrate (Cd and Pb) complexes by ESI-MS in aqueous solution

The combined use of ESI-MS, FTIR-ATR and theoretical calculations for the determination of metal-citrate (metal=Cd and Pb) structures are reported. Mass spectrometry allowed to determine the stoichiometry 1:1 and 2:1 of the complexes, corroborating the theoretical calculations. The species found in the ratio 2:1 had their molecular structures readjusted, since the deprotonation of citric acid differed from what was simulated. The calculations of thermodynamic stability (ΔH(0)(aq.)) for the complexes obtained by B3LYP/LANL2DZ were more exoenergetic than those found by PM6. However, for both methods, the stability of the complexes follows a trend, that is, the lowest-energy isomers in PM6 are also the most stable in B3LYP/LANL2DZ. The infrared analysis suggested that carboxyl groups are complexation sites and hydrogen bonds can help in the stability of the complexes. The vibrational frequencies in B3LYP/LANL2DZ had a good correlation with the experimental infrared results.

Absorção e translocação de silício em mudas de eucalipto cultivadas em latossolo e cambissolo

Com o objetivo de estudar a absorcao e a translocacao de Si em mudas de Eucalyptus grandis W. Hill. Ex Maiden cultivadas em amostras de Latossolo Vermelho distrofico e de Cambissolo Haplico Tb distrofico, foram realizados dois experimentos em casa-de-vegetacao. Cada solo foi submetido a tres incubacoes sequenciais para a aplicacao dos tratamentos: a) CaCO3+MgCO3 para manter o pH em torno de 6,0; b) fertilizacao basica com macro e micronutrientes; c) seis doses de Si (CaSiO3). As plantas foram cultivadas em vasos contendo 2,7 dm3 de solo. O teor de Si soluvel em agua no solo e o conteudo de Si nas raizes e parte aerea das plantas foram avaliados aos 60, 90 e 120 dias do transplantio, ajustando-se superficies de resposta dessas variaveis as doses de Si e as epocas. Determinaram-se os indices de eficiencia de absorcao e de utilizacao do Si pelas plantas e a porcentagem de Si translocado. Na fase inicial de crescimento (60 dias), as mudas absorveram muito pouco Si, e a eficiencia de translocacao foi maxima aos 60 dias, ficando a maior parte do elemento retida nas raizes a partir dessa epoca. O teor de Si soluvel em agua no solo reduziu-se com o tempo, mas a absorcao do elemento pelo eucalipto nao foi responsavel pelo fato. Os dados obtidos evidenciaram que o eucalipto nao e uma planta acumuladora de Si, embora seja responsiva ao mesmo.

Structural determination of Cu and Fe-Citrate complexes: theoretical investigation and analysis by ESI-MS

The combined use of ESI-MS (electrospray ionization-mass spectrometry) and theoretical calculations for the determination of citrate:metal (metal=Cu and Fe) structures are reported. Mass spectrometry allowed to determine the stoichiometry 1:1 and 2:1 of the complexes, corroborating the theoretical calculations. The species found in the ratio 2:1 had their calculated structures readjusted, from what was originally simulated, since the deprotonation of citric acid differed from what was before simulated. The thermodynamic stability (ΔH(aq.)(0)) of the complexes optimized at the B3LYP/LANL2DZ level was more exoenergetic than for the complexes found by the PM6 semi-empirical method.

Effects of Lead on the Content, Accumulation, and Translocation of Nutrients in Bean Plant Cultivated in Nutritive Solution

Increasing contents of lead (Pb; from 0 to 10 mg L−1) as contaminant were added in Clarks nutritive solution to evaluate the effects on content, accumulation, and translocation of macronutrients [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)] and micronutrients [copper (Cu), manganese (Mn), zinc (Zn), and iron (Fe)] in different parts of the bean plant (Phaseolus vulgaris L.). Experiments were built using an entirely randomized statistical arrangement and measurements were performed after 60 days of exposure to Pb. The contents of almost all nutrients decreased when Pb was added, except for P in root, Mg in fruits, and S in root and fruits. Reduction in accumulation of all nutrients in the three parts of plants was determined, and an increase in the translocation index was observed for the following nutrients: Mg and Zn in fruits and S in fruits and leaves. For the remaining nutrients, the translocation index diminished.