Parâmetros cinéticos de absorção de nitrogênio em cultivares de portaenxertos de pessegueiros.

Na seleção de cultivares de porta-enxertos de pessegueiros (Prunus persica L. Batsch) não são considerados os parâmetros cinéticos relacionados à eficiência de absorção de nutrientes, inclusive as formas de nitrogênio (N)

Genotoxic effect of aqueous extracts from South American Achyrocline and Gnaphalium species (Asteraceae: Gnaphalieae) on human lymphocytes

Crude drug and different extracts of Achyrocline satureioides (Lam.) DC., A. tomentosa Rusby, Gnaphalium cheiranthifolium Lam. and G. gaudichaudianum DC. (Gnaphalieae: Asteraceae) are widely used in South America mainly as digestives and hepatics. These are raw material for phytotherapics preparations and the manufacture of traditional bitter drinks. In order to establish some aspects on their safety, we have evaluated four different concentrations (1, 10, 100, and 1000 µL.mL-1) of the aqueous extracts of these plants against Single Cell Gel Electrophoresis Assay (SCGEA) in human peripheral blood lymphocytes. Results show a significant increase in damage index (p < 0.001) for all aqueous extracts concentrations assayed of the four plant species, in relation to negative control values. This is a contribution to the development of screenings related to the potential health risk associated with the consumption of South American medicinal plants, especially taking in mind that these plants are widely used as over-thecounter herbs.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Establishment of potassium reference values using Bayesian models in grapevines

Critical levels (CL) of available potassium (K) in soils and leaves and maximum technical efficiency (MTE) doses are relevant information to define the best K fertilization strategies. The aim of this study was to determine reference values of K in leaves and soil, using Bayesian analysis, in order to maximize grape yield and must quality of ‘Chardonnay’ and ‘Pinot Noir’ grown in a subtropical climate. The vines were subjected to applications of 0, 20, 40, 60 and 80 kg K2O ha−1 year−1. The CL and MTE doses of K, in leaves and soils, were determined using Bayesian hierarchical models. The range of probability of the occurrence of CL in leaves was 15.8 to 18.9 g K kg−1 in ‘Chardonnay’ and 16.8 to 19.1 g K kg−1 in ‘Pinot Noir’ at flowering. Moreover, the range was 15.3 to 18.1 g K kg−1 in ‘Chardonnay’ and 16.1 to 18.2 g K kg−1 in ‘Pinot Noir’ at veraison. In the soil, the CL of available K for ‘Chardonnay’ was 27.4 mg K kg−1 and for ‘Pinot Noir’ it was 23.2 mg K kg−1. The increase of K in leaves and soil increased the TSS, while the TTA decreased in both cultivars after sufficiency rate. The MTE was estimated in ‘Pinot Noir’. The proposition of CL and/or MTE doses of K can help increase the efficiency of K fertilization in vineyards

Photosynthetic activity and grape yield of 'Alicante Bouschet' (Vitis vinifera L.) grapevines submitted to nitrogen supply methods and doses.

The great majority of sandy soils present low nitrogen availability, generally below vines physiological demand, and therefore nitrogen fertilizer application, such as urea, is necessary. However, when urea is applied on the soil surface, the vine can use only a small amount of N. Thus, management strategies such as fertigation can increase N utilization by vine, reflecting in a greater photosynthetic activity and grape yield. The objective of this study was to evaluate the influence of nitrogen supply methods and doses on photosynthetic activity and grape yield of 'Alicante Bouschet' grapevines cultivated in sandy soil. The experiment was carried out in Santana do Livramento, in the southern region of Brazil, in a vineyard planted in 2011. The cultivar was 'Alicante Bouschet' grafted on '1103 Paulsen'. The experimental design was of randomized blocks in a bifactorial arrangement (dose x method). The N source used was urea (45 % N). The 0, 20, 60 and 100 kg N·ha-1 doses were applied on the soil surface, without irrigation (NWI) and via fertigation (NF). Photosynthetic activity, N concentration in leaves and grape yield during two growing seasons were evaluated. The application of N doses in soil increased N concentration in grapevine leaves by up to 53 % in NF and 18 % in NWI methods but did not affect yield. Strong correlations between yield and water use efficiency were also observed, evidencing a certain synchronism between the physiological demand of the grapevine and the offer of the adequate N dose by a more efficient method

The Intersection of Purine and Mitochondrial Metabolism in Cancer

Nucleotides are essential to cell growth and survival, providing cells with building blocks for DNA and RNA, energy carriers, and cofactors. Mitochondria have a critical role in the production of intracellular ATP and participate in the generation of intermediates necessary for biosynthesis of macromolecules such as purines and pyrimidines. In this review, we highlight the role of purine and mitochondrial metabolism in cancer and how their intersection influences cancer progression, especially in ovarian cancer. Additionally, we address the importance of metabolic rewiring in cancer and how the evolving landscape of purine synthesis and mitochondria inhibitors can be potentially exploited for cancer treatment

Recuperação anual e residual do nitrogênio derivado da ureia por pessegueiros.

A ureia é o fertilizante nitrogenado normalmente mais usado em pomares porque possui elevada concentração de N e menor custo por unidade do nutriente (BRUNETTO et al., 2016). Porém, a uréia no solo é rapidamente hidrolisada por enzimas ureases extracelulares produzidas por microrganismos, tais como bactérias e fungos, produzindo carbonato de amônio (NH4 +)2CO3, que não é estável no sol

Aproveitamento pelos pessegueiros do nitrogênio derivado do fertilizante.

O pêssegueiro pertencente à família Rosaceae, gênero Prunnus é a terceira espécie de árvores frutíferas mais produzida no mundo, atrás da macieira e pereira (BYRNE et al., 2012). No Brasil, o Rio Grande do Sul (RS) possui a maior área cultivada com pessegueiros. A dose de N em pessegueiros normalmente é definida com base no conteúdo de matéria orgânica do solo ou na concentração de N em folhas, sendo considerada a expectativa de produtividade e parâmetros de crescimento (CQFS-RS/SC, 2016). O N é aplicado parceladamente ao longo dos estágios fenológicos. Porém, não é suficientemente conhecido o melhor modo de parcelamento do N, nem tampouco as percentagens reais de N aproveitadas pelos pessegueiros. Isso pode ser obtido com o uso de isótopos estáveis de 15N. O objetivo do presente estudo foi avaliar o aproveitamento pelo pessegueiro em produção do N derivado do fertilizante aplicado em dois modos de parcelamento