Vascular O-GlcNAcylation augments reactivity to constrictor stimuli by prolonging phosphorylated levels of the myosin light chain

O-GlcNAcylation is a modification that alters the function of numerous proteins. We hypothesized that augmented O-GlcNAcylation levels enhance myosin light chain kinase (MLCK) and reduce myosin light chain phosphatase (MLCP) activity, leading to increased vascular contractile responsiveness. The vascular responses were measured by isometric force displacement. Thoracic aorta and vascular smooth muscle cells (VSMCs) from rats were incubated with vehicle or with PugNAc, which increases O-GlcNAcylation. In addition, we determined whether proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation. PugNAc enhanced phenylephrine (PE) responses in rat aortas (maximal effect, 14.2±2 vs 7.9±1 mN for vehicle, n=7). Treatment with an MLCP inhibitor (calyculin A) augmented vascular responses to PE (13.4±2 mN) and abolished the differences in PE-response between the groups. The effect of PugNAc was not observed when vessels were preincubated with ML-9, an MLCK inhibitor (7.3±2 vs 7.5±2 mN for vehicle, n=5). Furthermore, our data showed that differences in the PE-induced contractile response between the groups were abolished by the activator of AMP-activated protein kinase (AICAR; 6.1±2 vs 7.4±2 mN for vehicle, n=5). PugNAc increased phosphorylation of myosin phosphatase target subunit 1 (MYPT-1) and protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), which are involved in RhoA/Rho-kinase-mediated inhibition of myosin phosphatase activity. PugNAc incubation produced a time-dependent increase in vascular phosphorylation of myosin light chain and decreased phosphorylation levels of AMP-activated protein kinase, which decreased the affinity of MLCK for Ca2+/calmodulin. Our data suggest that proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation, favoring vascular contraction

Produção do maxixe-do-reino em função do sistema de tutoramento e do espaçamento Yield of achocha as a result of the staking system and spacing

Foram avaliadas as características produtivas do maxixe-do-reino [Cyclanthera pedata L. Schrad.)], em função de sistemas de tutoramento e do espaçamento. O experimento foi conduzido na UFMG em Montes Claros. Empregou-se o delineamento experimental de blocos ao acaso, com quatro repetições e arranjo em faixas 3 x 2, sendo três sistemas de tutoramento (cerca vertical, cerca cruzada com varas e cerca cruzada com fitilho de polietileno) e dois espaçamentos entre plantas (1,0 x 0,5 m e 1,0 x 1,0 m), totalizando 24 parcelas. Cada faixa correspondeu a um sistema de condução. As características produtivas dos frutos em número e em peso foram significativamente maiores nas plantas cultivadas no sistema de cerca vertical, onde cada planta produziu, em média, 56 frutos, equivalendo ao peso de 2,68 kg. Nesse sistema houve melhor fixação dos ramos no tutor e menor incidência de frutos danificados por contato com o solo. No espaçamento 1,0 x 1,0 m houve maior rendimento de frutos por planta em número e em peso, resultante do menor efeito competição entre plantas por água, nutrientes e luz. Já, a produtividade por área foi menor devido ao menor número de plantas por ha.<br>A field experiment was carried out to evaluate the yield of achocha [Cyclanthera pedata L. Schrad.) ] in Montes Claros, Minas Gerais State, Brazil, as a result of the staking system and within-row spacing. The experimental design was of randomized blocks with four replications, arranged in a scheme 3 x 2, being three staking systems (vertical fence, pole-trellised fence and polyethylene ribbon-trellised fence) and two within-row spacings (1,0 x 1,0 m and 1,0 x 0,5 m), totalizing 24 plots. The fruit number and weight were significantly higher from plants cultivated in the system of vertical fence, where each plant produced 56 fruits on average, corresponding to 2,68 kg. In this system plants presented better fixation to the tutor, besides having minor incidence of damaged fruits caused by the contact with the soil. Highest number, weight of fruits and yield were observed when within-row spacing of 1,0 x 1,0 m was adopted, due to lesser effect of competition between plants for water, nutrients and light. However the yield per area was less due to lower number of plants per ha

Produção de morangos a partir de fertilizantes alternativos em pré-plantio Pre-planting fertilization effects on strawberry fruit yield

O trabalho teve como objetivo avaliar doses de fertilizantes alternativos na adubação de pré-plantio quanto à produção de frutos de morangueiro. Os tratamentos foram baseados em doses de adubação NPK (kg ha-1) recomendada para a cultura do morangueiro em que as doses de torta de mamona (TM), fosforita alvorada (FA) e cloreto de potássio (KCl) variaram de acordo com a recomendação da análise de solo. Os tratamentos foram dispostos em delineamento em blocos casualizados em parcelas subdivididas, sendo as cultivares dispostas na parcela e as adubações na subparcela. Foi utilizado um esquema fatorial 2x4, em que o fator cultivar apresentou dois níveis: 'Camarosa' e 'Camino Real', e o fator adubação de pré-plantio, quatro níveis. As avaliações realizadas foram produção de frutos por planta, massa seca da parte aérea e índice de clorofila. A cultivar 'Camarosa' apresentou maior número e massa de frutos por planta e maior massa seca da parte aérea. A cultivar 'Camino Real' apresentou maior massa média por fruto e maior índice de clorofila. Com relação às doses de adubação de pré-plantio que propiciaram maior número e massa de frutos por planta, foram 1.937kg ha-1 e 1.713kg ha-1 de adubo, respectivamente.<br>The study aimed to evaluate the doses of alternative fertilizer pre-planting fertilization on strawberries yield. The treatments were based on doses of NPK (kg ha-1) recommended for strawberry culture in which the doses of castor bean (TM), phosphorite dawn (FA) and potassium chloride (KCl) varied according to the recommendation of the soil analysis. The treatments were arranged in randomized blocks design at split plots with cultivars in the plot and fertilization in the sub-plot. It was used a factorial 2x4 arrangement, in which the cultivar factor had two levels: 'Camarosa' and 'Camino Real', and the pre-planting fertilizer factor with four levels. The evaluations were fruit yield per plant, shoot dry mass and chlorophyll content. 'Camarosa' cultivar showed a greater number and weight of fruits per plant and higher dry mass shoots. Cultivar 'Camino Real' had the largest average per fruit and increased chlorophyll content. Regarding the fertilization rates of pre-planting, which fostered a greater number and weight of fruits per plant, it was 1937kg ha-1 and 1713kg ha-1 of fertilizer, respectively