Rooting Pattern Distribution and Spatial Variability of Italian Ryegrass (Lolium Multiflorum Lam) in a Mediterranean Region

It is estimated that less than 10% of the studies on pastures and forages have evaluated the subterranean biomass production. The objective of this study was to evaluate for a Mediterranean region the rooting characteristics and spatial variability of Italian ryegrass (Lolium multiflorum Lam) under two different soil water status conditions

Respostas de quatro cultivares de arroz à aplicação de nitrogênio amoniacal com um inibidor de nitrificação

A study made in a greenhouse on the effects of soil applied ammonium-N with and without a nitrification inhibitor on dry matter accumulation, nitrogen and free-sugar contents of four rice (Oriza sativa L.) cultivars. The rice cultivars were Pratão precoce, IR-L63, IAC-25 and De Abril. N-NH4 (150 ppm) was either applied once at seeding or split in three applications (0,23 and 38 days after seeding). Plants had a higher dry weight in the treatments without than in those with the nitrification inhibitor. Application of 150 ppm of N-NH4 plus a nitrification inhibitors at seeding, drastically reduced plant dry weight. Among cultivars, De Abril, showed the highest resistance to high levels of N-NH4 in soils, with or without nitrification inhibitor. Decrease in soil pH was higher in the treatments without inhibitor than in the treatments with inhibitor. Nitrification in the former is assumed to be responsible for this lower pH, while in the later, pH drop may be caused mainly by H+ -extrusion due to higher cation than anion uptake. Plants without a nitrification inhibitor had higher levels of free amino-N than plants with the inhibitor, the reverse was true for the free sugars levels. There was a negative (- 0,67**) correlation between the root/shoot relationship and dry matter accumulation of plants under the NH4 plus a nitrification inhibitor treatments. It is suggested that, under proper conditions. NH4-N and a nitrification inhibitor could be used in upland rice fertilization, with a reduction in N- losses and pH drop.Estudo, em casa de vegetação, sobre o efeito de nitrogênio amoniacal, em uma aplicação única ou parcelada, com e sem inibidor de nitrificação, sobre a produção de matéria seca e os teores de nitrogênio e açúcares solúveis, em quatro cultivares de arroz (Oryza sativa L.): Pratão precoce. IRL63, IAC-25 e De Abril. A aplicação do N-NH4, (150 ppm) em dose única por ocasião da semeadura ou em três aplicações (0, 23 e 38 dias após a semeadura) com o inibidor de nitrificação, resultou em uma redução drástica do peso seco das plantas. Nos tratamentos sem inibidor, as plantas acumularam mais matéria seca que nos tratamentos com inibidor. A cv. De Abril revelou uma resistência sensivelmente maior a doses elevadas de N-NH4 no solo, com ou sem o inibidor. A queda de pH do solo (∆ pH) foi maior nos tratamentos sem inibidor. Atribui-se essa diferença à acidez provocada pela nitrificação, enquanto que nos tratamentos com inibidor, a queda de pH estaria controlada basicamente pela extrusão de H+, provocada pela absorção de um excesso de cátions (NH+4) em relação a ânions. As plantas dos tratamentos sem inibidor acumularam maiores teores de amino-N livre que as plantas dos tratamentos com inibidor. Inversamente, as plantas dos tratamentos com inibidor apresentaram menores teores de açúcares livres, em relação às plantas dos tratamentos sem inibidor. Observou-se uma correlação negativa (-0,67**), entre a relação raiz/parte aérea e a acumulação de matéria seca das plantas dos tratamentos com inibidor de nitrificação. Sugere-se que a fertilização de solos com formas reduzidas de N em arroz de sequeiro pode ser feita com a aplicação simultânea de um inibidor de nitrificação. Dependendo da variedade usada e dos métodos de aplicação, as perdas de N por lixiviação e as quedas de pH do solo podem ser sensivelmente reduzidas

Aspectos climáticos do noroeste fluminense, RJ.

bitstream/CNPS/11829/1/doc_43_2003_noroeste_fluminense.pd

Uso de clorofilometro na avaliação da adubação nitrogenada e potássica no capim Tifton 85.

RESUMO - Objetivou-se com este trabalho aferir o comportamento de um clorofilometro na gramínea forrageira Tifton 85 (Cynodon spp. cv. Tifton 85) e sua relação com a produção de massa seca em resposta à adubação nitrogenada e potássica. No primeiro ensaio de campo realizado foi feita a aplicação de nitrogênio e potássio separados em três tratamentos: 0,75 e 150kg/ha/corte, segundo um delineamento em blocos casualizados, com quatro repetições. Os teores de clorofila total, extraídos da primeira lâmina foliar totalmente expandida, correlacionaram-se bem com as leituras do clorofilometro e foram afetados pelas doses de N e número de cortes. No segundo corte, os teores de clorofila total foram significativamente maiores que no primeiro, enquanto a massa verde seca total da parte aérea respondeu apenas às doses de N, o que sugere a existência de uma produção ?de luxo? de clorofilas. No segundo ensaio, os tratamentos consistiram de cinco doses de N e K: 0; 150; 300; 450 e 600 kg/ha, dispostos na forma de blocos inteiramente casualizados, com quatro repetições e ao final de um período de 28 dias, os teores de clorofila total, as leituras do clorofilometro e a matéria seca de folhas variaram, segundo um modelo quadrático, em resposta às doses de N (entre 0 e 600kg N/ha) sem evidencias de produção de luxo de clorofilas. Embora esta última situação seja provavelmente a situação normal, a melhoria no desempenho do clorofilometro a altos níveis de disponibilidade de N demandará novos estudos com relação às frações nitrogenadas que se acumulam na planta nessas condições. ABSTRACT - The aim of this study was to assess the performance of a chlorophyll meter and its relation to dry matter production of Tifton 85 (Cynodon spp. cv. Tifton 85), in response to nitrogen fertilization. In the first field trial, the total chlorophyll contents extracted from the uppermost fully expanded leaf blade correlated well with chlorophyll meter readings and were affected by N rates and cut number. In the second cut in the first field trial, total chlorophyll contents were higher than the first cut while total dry mass of green shoots responded only to N rates, suggesting that there was a ?luxury? production of chlorophylls. In the second field trial, at the end of a single regrowth period of 28 days, total chlorophyll contents, chlorophyll meter readings and dry leaf biomass varied harmonically, according to a quadratic model of response to N dose (0 - 600kg N/ha), without evidence of a supraoptimal production of chlorophylls. Although this last it is probably the normal situation, the refinement of the chlorophyll meter sensitivity to high levels of soil N availability, will demand news studies in order to clarify the status of the nitrogen fractions accumulated in the plant in these conditions

Kaposi's Sarcoma Associated Herpes Virus (KSHV) Induced COX-2: A Key Factor in Latency, Inflammation, Angiogenesis, Cell Survival and Invasion

Kaposi's sarcoma (KS), an enigmatic endothelial cell vascular neoplasm, is characterized by the proliferation of spindle shaped endothelial cells, inflammatory cytokines (ICs), growth factors (GFs) and angiogenic factors. KSHV is etiologically linked to KS and expresses its latent genes in KS lesion endothelial cells. Primary infection of human micro vascular endothelial cells (HMVEC-d) results in the establishment of latent infection and reprogramming of host genes, and cyclooxygenase-2 (COX-2) is one of the highly up-regulated genes. Our previous study suggested a role for COX-2 in the establishment and maintenance of KSHV latency. Here, we examined the role of COX-2 in the induction of ICs, GFs, angiogenesis and invasive events occurring during KSHV de novo infection of endothelial cells. A significant amount of COX-2 was detected in KS tissue sections. Telomerase-immortalized human umbilical vein endothelial cells supporting KSHV stable latency (TIVE-LTC) expressed elevated levels of functional COX-2 and microsomal PGE2 synthase (m-PGES), and secreted the predominant eicosanoid inflammatory metabolite PGE2. Infected HMVEC-d and TIVE-LTC cells secreted a variety of ICs, GFs, angiogenic factors and matrix metalloproteinases (MMPs), which were significantly abrogated by COX-2 inhibition either by chemical inhibitors or by siRNA. The ability of these factors to induce tube formation of uninfected endothelial cells was also inhibited. PGE2, secreted early during KSHV infection, profoundly increased the adhesion of uninfected endothelial cells to fibronectin by activating the small G protein Rac1. COX-2 inhibition considerably reduced KSHV latent ORF73 gene expression and survival of TIVE-LTC cells. Collectively, these studies underscore the pivotal role of KSHV induced COX-2/PGE2 in creating KS lesion like microenvironment during de novo infection. Since COX-2 plays multiple roles in KSHV latent gene expression, which themselves are powerful mediators of cytokine induction, anti-apoptosis, cell survival and viral genome maintainence, effective inhibition of COX-2 via well-characterized clinically approved COX-2 inhibitors could potentially be used in treatment to control latent KSHV infection and ameliorate KS

Lipid (per) oxidation in mitochondria:an emerging target in the ageing process?

Lipids are essential for physiological processes such as maintaining membrane integrity, providing a source of energy and acting as signalling molecules to control processes including cell proliferation, metabolism, inflammation and apoptosis. Disruption of lipid homeostasis can promote pathological changes that contribute towards biological ageing and age-related diseases. Several age-related diseases have been associated with altered lipid metabolism and an elevation in highly damaging lipid peroxidation products; the latter has been ascribed, at least in part, to mitochondrial dysfunction and elevated ROS formation. In addition, senescent cells, which are known to contribute significantly to age-related pathologies, are also associated with impaired mitochondrial function and changes in lipid metabolism. Therapeutic targeting of dysfunctional mitochondrial and pathological lipid metabolism is an emerging strategy for alleviating their negative impact during ageing and the progression to age-related diseases. Such therapies could include the use of drugs that prevent mitochondrial uncoupling, inhibit inflammatory lipid synthesis, modulate lipid transport or storage, reduce mitochondrial oxidative stress and eliminate senescent cells from tissues. In this review, we provide an overview of lipid structure and function, with emphasis on mitochondrial lipids and their potential for therapeutic targeting during ageing and age-related disease

Parâmetros morfológicos para estabelecer tolerância diferencial à toxicidade de alumínio em cultivares de arroz Morphological parameters to determine differential tolerance of rice cultivars to aluminium toxicity

Dois experimentos em casa de vegetação foram conduzidos visando identificar parâmetros morfológicos ligados à tolerância ao alumínio (Al) e estabelecer a concentração de Al e o tempo de cultivo suficientes para a expressão da tolerância ao Al, em duas cultivares de arroz, em solução nutritiva. Plantas de determinado comprimento radicular máximo foram transferidas para solução nutritiva com quatro concentrações de Al (0, 80, 160 e 320 mimol L-¹), a pH 4,0. Em cada coleta, foram medidos o comprimento máximo radicular, área radicular, área foliar e massa seca de raízes e parte aérea. Apenas os parâmetros morfológicos ligados ao sistema radicular possibilitaram o reconhecimento da tolerância diferencial das cultivares; a elongação radicular relativa foi a medida mais sensível. Quatro dias de exposição ao Al foram suficientes para a detecção da tolerância diferencial por meio da elongação radicular relativa. Os procedimentos estabelecidos nos experimentos podem ser utilizados para a avaliação de um número maior de cultivares.<br>Two nutrient solution greenhouse experiments were conducted to identify morphological parameters that express Al tolerance and to determine the influence of period of plant growth and Al concentration necessary for tolerance discrimination, in two rice cultivars. Plants of known maximum root length were transferred to nutrient solution at four levels of Al (0, 80, 160 and 320 mumol L-1) with a pH 4.0. In each collection, the new maximum root length was measured in addition to root and leaf areas, and root and shoot dry weights. Only the morphological parameters related to the root system differentiated Al tolerance of the cultivars, and relative root elongation was the most sensitive. Four days of exposure to Al were sufficient to detect differences in Al tolerance by means of relative root elongation. The methods established in this study can be useful in evaluating larger number of cultivars