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Alvarez-Pizarro J.C.,Federal University of Ceara | Gomes-Filho E.,Federal University of Ceara | Prisco J.T.,Federal University of Ceara | Grossi-De-Sa M.F.,Embrapa Recursos Geneticos e Biotecnologia | And 3 more authors.
Biologia Plantarum | Year: 2014

We studied the influence of inorganic nitrogen sources (NO3 - or NH4 +) and potassium deficiency on expression and activity of plasma membrane (PM) H+-ATPase in sorghum roots. After 15 d of cultivation at 0.2 mM K+, the plants were transferred to solutions lacking K+ for 2 d. Then, K+ depletion assays were performed in the presence or absence of vanadate. Further, PMs from K+-starved roots were extracted and used for the kinetic characterization of ATP hydrolytic activity and the immunodetection of PM H+-ATPase. Two major genes coding PM H+-ATPase (SBA1 and SBA2) were analyzed by real-time PCR. PM H+-ATPase exhibited a higher Vmax and Km in NH4 +-fed roots compared with NO3 - -fed roots. The optimum pH of the enzyme was slightly lower in NO3 - -fed roots than in NH4 +-fed roots. The vanadate sensitivity was similar. The expressions of SBA1 and SBA2 increased in roots grown under NH4 +. Concomitantly, an increased content of the enzyme in PM was observed. The initial rate of K+ uptake did not differ between plants grown with NO3 - or NH4 +, but it was significantly reduced by vanadate in NH4 +-grown plants. © 2014 Springer Science+Business Media Dordrecht. Source


Alvarez-Pizarro J.C.,Federal University of Ceara | Gomes-Filho E.,Federal University of Ceara | Prisco J.T.,Federal University of Ceara | Grossi-de-Sa M.F.,Embrapa Recursos Geneticos e Biotecnologia | And 2 more authors.
Journal of Plant Physiology | Year: 2011

The effect of external inorganic nitrogen and K+ content on K+ uptake from low-K+ solutions and plasma membrane (PM) H+-ATPase activity of sorghum roots was studied. Plants were grown for 15 days in full-nutrient solutions containing 0.2 or 1.4mM K+ and inorganic nitrogen as NO3 -, NO3 -/NH4 + or NH4 + and then starved of K+ for 24, 48 and 72h. NH4 + in full nutrient solution significantly affected the uptake efficiency and accumulation of K+, and this effect was less pronounced at the high K+ concentration. In contrast, the translocation rate of K+ to the shoot was not altered. Depletion assays showed that plants grown with NH4 + more efficiently depleted the external K+ and reached higher initial rates of low-K+ uptake than plants grown with NO3 -. One possible influence of K+ content of shoot, but not of roots, on K+ uptake was evidenced. Enhanced K+-uptake capacity was correlated with the induction of H+ extrusion by PM H+-ATPase. In plants grown in high K+ solutions, the increase in the active H+ gradient was associated with an increase of the PM H+-ATPase protein concentration. In contrast, in plants grown in solutions containing 0.2mM K+, only the initial rate of H+-pumping and ATP hydrolysis were affected. Under these conditions, two specific isoforms of PM H+-ATPase were detected, independent of the nitrogen source and deficiency period. No change in enzyme activity was observed in NO3 --grown plants. The results suggest that K+ homeostasis in NH4 +-grown sorghum plants may be regulated by a high capacity for K+ uptake, which is dependent upon the H+-pumping activity of PM H+-ATPase. © 2011 Elsevier GmbH. Source


Dias S.C.,Embrapa Recursos Geneticos e Biotecnologia | Dias S.C.,University of Brasilia | da Silva M.C.M.,Embrapa Recursos Geneticos e Biotecnologia | Teixeira F.R.,Embrapa Recursos Geneticos e Biotecnologia | And 6 more authors.
Pesticide Biochemistry and Physiology | Year: 2010

Innumerable proteinaceous α-amylase inhibitors have been isolated and identified from different plant species. Among them, an α-amylase inhibitor gene with bioinsecticidal potential toward Anthonomus grandis (cotton boll weevil) was previously identified in rye seeds (Secale cereale). This cereal inhibitor was expressed in tobacco plants (Nicotiana tabacum) under control of phytohemaglutinin promoter by using Agrobacterium tumefasciens - mediated transformation. Presence of αBIII-rye gene and further protein expression were confirmed by PCR and Western blot analysis, respectively. Immunological assays indicated that the recombinant inhibitor was expressed in concentration range from 0.1% to 0.28% (w:w) of the total protein in tobacco seeds of R0 plants. From 14 independent transformants, five plants with expression levels between 0.20% and 0.28% in seeds were in vitro assayed against A. grandis amylolytic enzymes causing clear inhibition. Moreover, bioassays using transgenic seed flour mixture for artificial diet produced 74% mortality in A. grandis first larval instar. These data suggest that rye inhibitor could be a promising biotechnological tool for produce transgenic cotton plants with an increased resistance to cotton boll weevil. Moreover, αBIII-rye gene should be considered a potential compound for a pyramiding strategy aiming to delay insect-resistance. © 2010. Source


Oliveira A.S.,Centro Universitario Unieuro | Oliveira A.S.,University of Aalborg | Tibana R.A.,Centro Universitario Unieuro | de Aguiar F.,Centro Universitario Unieuro | And 2 more authors.
Revista Brasileira de Medicina do Esporte | Year: 2010

Incremental treadmill tests are widely used for prescription of aerobic and anaerobic training. Physiological and kinematics parameters are changed by the progressive nature of this activity. However, there is no consensus on how anthropometric characteristics may affect the incremental test performance. Therefore, the aims of this study were (1) to verify the effects of the incremental treadmill test on the blood lactate concentration ([LAC]), glucose concentration ([GLU]), step frequency (SF) and step length (SL), and (2) to correlate anthropometric data (body mass, height, %body fat) to changes in [LAC] and [GLU]. Thirteen healthy males volunteered to this study and performed an incremental running test on a treadmill (start: 8 km/h, with progressive increases [1 km/h] at each three minute until exhaustion). [LAC] and [GLU] were registered before and 3 min after the incremental test performance. SF and SL were registered for each running speed by digital images at the sagital plane. As results, we verified that [LAC] and [GLU] before the incremental test (1.94 ± 0.4 mmol/L and 94.3 ± 7 mg/dL, respectively) were significantly lower (p < 0.05) than after the incremental test (9.51 ± 2.7 mmol/L and 126 ± 16. mg/dL, respectively). In addition, SF and SL presented significant increase (p < 0.05) throughout the incremental test. [LAC] presented inverse and significant correlations (p < 0.05) to height and body mass. Thus, an incremental treadmill running test affects kinematic (SF and SL) and physiological conditions (muscular fatigue, as consequence of the speed increase). Besides this, shorter and lighter subjects may present higher metabolite concentrations after this type of test. Source


Oliveira A.S.,Centro Universitario Unieuro | Oliveira A.S.,University of Aalborg | Tibana R.A.,Centro Universitario Unieuro | Aguiar F.,Centro Universitario Unieuro | And 3 more authors.
Science and Sports | Year: 2011

Aims: To verify the effects of previous interval training session on physiological and kinematic parameters during continuous running at ventilatory threshold. Methods: Ten healthy male performed initially an incremental running test, in order to determine ventilatory threshold and maximal aerobic capacity. In another session, subjects performed three tasks as follows: (1) previous five-minute run at ventilatory threshold. After ten minutes rest: (2) interval training session (8 × 1-min at maximal velocity, alternated to one-minute at 50% maximal velocity). After 15 minutes rest: (3) posterior five-minute run at ventilatory threshold. Heart rate, ventilation, blood glucose and lactate concentrations, perceived exertion, stride frequency, stance period and swing period were compared before and after the interval training session. Results: Significant increases were found in heart rate (~12%), ventilation (~23%), blood glucose (~28%), blood lactate (230%), perceived exertion (~25%) and stride frequency (~5%) after interval training. Conclusion: High-intense running stimuli affect physiological, perceptual and kinematics of a constant moderate intensity running, which could influence training session programmes, considering the impairment overall running performance. © 2010 Elsevier Masson SAS. Source

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