Turnover de carbono nos tecidos de frangos de corte em diferentes fases de crescimento

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

Turnover do δ¹³C na substituição de dietas com ingredientes de diferentes ciclos fotossintéticos em ovos de codornas japonesas (Coturnix coturnix japonica)

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

Método de análise isotópica (δ13C) e quantificação da percentagem de fonte C3 em sucos de uva comerciais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

The objective of this work was to evaluate the utilization by corn plants of P from triple superphosphate fertilizer labeled with P-32 (P-32-TSP), and of P from soil as affected by N rates and by the green manures (GM) sunn hemp (Crotalaria juncea) and millet (Pennisetum glaucum). The experiment was carried out using pots filled with 5 kg Oxisol (Rhodic Hapludox). A completely randomized design was used, in a 4x4x2 factorial arrangement, with four replicates. The treatments were: four P rates as TSP (0, 0.175, 0.350, and 0.700 g P per pot); four N rates as urea (0, 0.75, 1.50, and 2.25 g N per pot); and sunn hemp or millet as green manure. The additions of N and P by the GM were taken into account. After grain physiologic maturation, corn dry matter, P contents, accumulated P, and P recovery in the different treatments were measured. P-32-TSP recovery by corn increased with N increasing rates, and decreased with increasing rates of P-32-TSP. The mineral fertilizer provides most of the accumulated P by corn plants. The recovery of P-32-TSP by corn was 13.12% in average. The green manure species influence the assimilation of P-32-TSP by the plants.

Isotope determination of sulfur by mass spectrometry in soil samples

Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S) with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS) in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO4(2-)), which was determined by dry combustion with alkaline oxidizing agents. The total S-SO4(2-) concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO2 gas, BaSO4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO3. The isotope determination of S (atom % 34S atoms) was carried out by isotope ratio mass spectrometry (IRMS). In this work, the labeled material (K2(34)SO4) was used to validate the method of isotopic determination of S; the results were precise and accurate, showing the viability of the proposed method.

Study of the 3-Hydroxy Eicosanoyl-Coenzyme A Dehydratase and (E)-2,3 Enoyl-Coenzyme A Reductase Involved in Acyl-Coenzyme A Elongation in Etiolated Leek Seedlings1

(R,S)-[1-14C]3-Hydroxy eicosanoyl-coenzyme A (CoA) has been chemically synthesized to study the 3-hydroxy acyl-CoA dehydratase involved in the acyl-CoA elongase of etiolated leek (Allium porrum L.) seedling microsomes. 3-Hydroxy eicosanoyl-CoA (3-OH C20:0-CoA) dehydration led to the formation of (E)-2,3 eicosanoyl-CoA, which has been characterized. Our kinetic studies have determined the optimal conditions of the dehydration and also resolved the stereospecificity requirement of the dehydratase for (R)-3-OH C20:0-CoA. Isotopic dilution experiments showed that 3-hydroxy acyl-CoA dehydratase had a marked preference for (R)-3-OH C20:0-CoA. Moreover, the very-long-chain synthesis using (R)-3-OH C20:0-CoA isomer and [2-14C]malonyl-CoA was higher than that using the (S) isomer, whatever the malonyl-CoA and the 3-OH C20:0-CoA concentrations. We have also used [1-14C]3-OH C20:0-CoA to investigate the reductant requirement of the enoyl-CoA reductase of the acyl-CoA elongase complex. In the presence of NADPH, [1-14C]3-OH C20:0-CoA conversion was stimulated. Aside from the product of dehydration, i.e. (E)-2,3 eicosanoyl-CoA, we detected eicosanoyl-CoA resulting from the reduction of (E)-2,3 eicosanoyl-CoA. When we replaced NADPH with NADH, the eicosanoyl-CoA was 8- to 10-fold less abundant. Finally, in the presence of malonyl-CoA and NADPH or NADH, [1-14C]3-OH C20:0-CoA led to the synthesis of very-long-chain fatty acids. This synthesis was measured using [1-14C]3-OH C20:0-CoA and malonyl-CoA or (E)-2,3 eicosanoyl-CoA and [2-14C]malonyl-CoA. In both conditions and in the presence of NADPH, the acyl-CoA elongation activity was about 60 nmol mg−1 h−1, which is the highest ever reported for a plant system.

Nd and Sr isotopic compositions and isotope dilution trace element concentrations from 7 sediment cores along the southeast Greenland margin

The Nd and Sr isotopic compositions of Quaternary glacial and glacimarine siliciclastic sediments deposited along the margin of southeast Greenland were determined to assess the roles of the Greenland, Iceland, and more distal ice sheets in delivering detritus to this portion of the northern North Atlantic. The isotopic compositions of detritus generated by portions of the southern Greenland Ice Sheet were defined through measurements of till and trough mouth fan sediments. Massive diamicts from the Scoresby Sund trough mouth fan show a restricted range of e-Nd (-11.8 to -16.6) and 87Sr/86Sr (0.7192-0.7246) consistent with their derivation from mixtures of sediments derived from Paleoproterozoic and/or Caledonian basement and Tertiary Greenland basalts. Further south at Kangerlussuaq, till isotopic compositions covary with the underlying basement type, with low e-Nd values in the inner fiord (-18.1) reflecting the erosion of the local Precambrian gneisses, but with higher e-Nd values (-2.3 to 2.5) found where the trough crosses East Greenland Tertiary basalts. Fine-grained (< 63 µm) sediments deposited along the southeast Greenland margin also show regular spatial isotopic variations. Ambient sediments and ice-rafted detritus in the southern Irminger Basin trend towards low e-Nd values (to ~ -28) and 87Sr/86Sr ratios (~ 0.711 to ~ 0.715) and are likely derived from proximal Archean gneisses of SE Greenland. Further north in the northern Irminger and Blosseville Basins, sediments trend toward much higher e-Nd (> -4) and low 87Sr/86Sr (< 0.709) reflecting a component derived from the local Iceland volcanic rocks and/or the East Greenland Tertiary basalts. In all three regions, the locally-derived detritus is intermixed with sediment with an intermediate e-Nd value (~ -10) and 87Sr/86Sr (~ 0.718) that was likely delivered by icebergs emanating from the Eurasian Ice Sheets and not from eastern Greenland. Deposition of glacial sediments from both proximal and distal (Eurasian) sources occurred adjacent to SE Greenland throughout the past 50 Ka, with periodic increases in IRD deposition at various times including those of Heinrich events 1, 2 and 4. These results suggest that at least the southern portions of the Greenland Ice Sheet experienced periodic instabilities during the Last Glacial period.