Exogenous application of salicylic acid induces salinity tolerance in eggplant seedlings

Abstract Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw.

Resumo Em condições de estresse salino, o crescimento das plantas é reduzido, em virtude, do desequilíbrio osmótico, nutricional e oxidativo. Contudo, o ácido salicílico atua na mitigação desse estresse abiótico por promover incremento no crescimento, fotossíntese, metabolismo do nitrogênio, síntese de osmorreguladores e enzimas antioxidantes. Nesse contexto, objetivou-se avaliar o efeito de doses de ácido salicílico sobre o crescimento e alterações fisiológicas de mudas de berinjela sob estresse salino. O experimento foi conduzido em casa de vegetação, onde os tratamentos foram distribuídos em blocos ao acaso utilizando uma matriz composta central Box com cinco níveis de condutividade elétrica da água de irrigação (CEa) (0,50; 1,08; 2,50; 3,92 e 4,50 dS m-1), associada a cinco doses de ácido salicílico (AS) (0,00; 0,22; 0,75; 1,28 e 1,50 mM), com quatro repetições e cada parcela composta por três plantas. Aos 40 dias após a semeadura, foram determinados a altura da planta, diâmetro do caule, número de folhas, área foliar, vazamento de eletrólito, teor relativo de água e massa seca total. A CEa e a aplicação de AS influenciaram no crescimento e nas alterações fisiológicas das mudas de berinjela. O aumento da CEa reduziu o crescimento na ausência de AS. O dano de membrana com o uso de AS manteve-se estável até 3,9 dS m-1 de CEa. O conteúdo relativo de água independentemente da CEa aumentou com 1 mM de SA. O uso de AS na concentração de 1 mM mitigou o efeito deletério da salinidade no crescimento das mudas até 2,50 dS m-1 de CEa.

Exogenous application of salicylic acid induces salinity tolerance in eggplant seedlings / Aplicação exógena de ácido salicílico induz tolerância à salinidade em mudas de berinjela

Abstract Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw.

Resumo Em condições de estresse salino, o crescimento das plantas é reduzido, em virtude, do desequilíbrio osmótico, nutricional e oxidativo. Contudo, o ácido salicílico atua na mitigação desse estresse abiótico por promover incremento no crescimento, fotossíntese, metabolismo do nitrogênio, síntese de osmorreguladores e enzimas antioxidantes. Nesse contexto, objetivou-se avaliar o efeito de doses de ácido salicílico sobre o crescimento e alterações fisiológicas de mudas de berinjela sob estresse salino. O experimento foi conduzido em casa de vegetação, onde os tratamentos foram distribuídos em blocos ao acaso utilizando uma matriz composta central Box com cinco níveis de condutividade elétrica da água de irrigação (CEa) (0,50; 1,08; 2,50; 3,92 e 4,50 dS m-1), associada a cinco doses de ácido salicílico (AS) (0,00; 0,22; 0,75; 1,28 e 1,50 mM), com quatro repetições e cada parcela composta por três plantas. Aos 40 dias após a semeadura, foram determinados a altura da planta, diâmetro do caule, número de folhas, área foliar, vazamento de eletrólito, teor relativo de água e massa seca total. A CEa e a aplicação de AS influenciaram no crescimento e nas alterações fisiológicas das mudas de berinjela. O aumento da CEa reduziu o crescimento na ausência de AS. O dano de membrana com o uso de AS manteve-se estável até 3,9 dS m-1 de CEa. O conteúdo relativo de água independentemente da CEa aumentou com 1 mM de SA. O uso de AS na concentração de 1 mM mitigou o efeito deletério da salinidade no crescimento das mudas até 2,50 dS m-1 de CEa.

Exogenous application of salicylic acid induces salinity tolerance in eggplant seedlings.

Under salt stress conditions, plant growth is reduced due to osmotic, nutritional and oxidative imbalance. However, salicylic acid acts in the mitigation of this abiotic stress by promoting an increase in growth, photosynthesis, nitrogen metabolism, synthesis of osmoregulators and antioxidant enzymes. In this context, the objective was to evaluate the effect of salicylic acid doses on the growth and physiological changes of eggplant seedlings under salt stress. The experiment was conducted in a greenhouse, where the treatments were distributed in randomized blocks using a central composite matrix Box with five levels of electrical conductivity of irrigation water (CEw) (0.50; 1.08; 2.50; 3.92 and 4.50 dS m-1), associated with five doses of salicylic acid (SA) (0.00; 0.22; 0.75; 1.28 and 1.50 mM), with four repetitions and each plot composed of three plants. At 40 days after sowing, plant height, stem diameter, number of leaves, leaf area, electrolyte leakage, relative water content, and total dry mass were determined. ECw and SA application influenced the growth and physiological changes of eggplant seedlings. Increasing the ECw reduced growth in the absence of SA. Membrane damage with the use of SA remained stable up to 3.9 dS m-1 of ECw. The relative water content independent of the CEw increased with 1.0 mM of SA. The use of SA at the concentration of 1.0 mM mitigated the deleterious effect of salinity on seedling growth up to 2.50 dS m-1 of ECw.

The effect of the antithyroid drug propylthiouracil on the alternative pathway of complement in rats.

The effect of propylthiouracil (PTU) on the lytic activity of complement in rat serum was investigated in vivo. Rats (180+/-10 g) were treated daily by gavage with PTU doses of 1-50 mg/200 g body weight for time intervals ranging from 1 to 30 days. Serum classical pathway (CP) and alternative pathway (AP) activities were determined 24 h after the last dose. A single dose of 50 mg/200 g body weight was administered to additional groups and the animals were sacrificed after periods of 1-48 h. The results showed a relatively small reduction ( approximately 30%) in CP activity, evident only in animals treated with 50 mg of PTU for three weeks. However, a clear and opposite effect of PTU, an increase in lytic activity reaching values up to 180% of controls, was observed on AP activity. This effect was seen at all PTU doses used, and occurred within 4 days of treatment with the highest dose. Maximum activity was observed at intermediate intervals, depending on the PTU dose, with a return to control levels occurring after the longer periods of treatment. The lytic activity of serum from animals treated with a single PTU dose of 50 mg/200 g body weight and sacrificed 1-48 h after dosing did not differ from controls. Serum levels of thyroid hormone (triiodo L-thyronine, T3, and thyroxine, T4) were determined in representative groups of treated animals (injected with 5 mg of PTU/200 g body weight/day). These were either undetectable or considerably lower than those of controls. The serum PTU levels of these rats increased for up to 22 days, reaching values of 2-4 microg/ml.PTU is described in the literature as a modulator of both cellular immune responses and antibody production. Upon complement activation fragments of complement components bind to immune complexes and to specific receptors on cells of the immune system. Thus, alteration in AP activity caused by PTU treatment suggests a possible mechanism by which the drug exerts its modulatory effect. Increased complement AP activity might affect events as antigen presentation and hence the onset and course of the immune response.

Effect of congenital hypothyroidism on cell density in the ganglion cell layer of the rat retina.

The effect of congenital hypothyroidism on the visual system of Wistar rats was studied by determining neuron density in the retinal ganglion cell layer. Retinae of adult rats from mothers treated with propylthiouracil, 50 mg/day, starting on the 15th day of pregnancy (PTU group), and of adult rats from untreated mothers (control group) were examined. Retinae were prepared, and the neurons in the nasotemporal region located above the optic disc were counted. Hypothyroid rats showed a significant reduction in the retinal area (about 6.8%), when compared to controls. The cell density in the retinal ganglion cell layer was significantly decreased in 6 PTU-treated compared to 5 control retinae in total (2,793 +/- 330 vs 3,704 +/- 662 neurons/mm2), nasal (3,031 +/- 580 vs 3,853 +/- 699 neurons/mm2) and temporal (2,555 +/- 155 vs 3,555 +/- 827 neurons/mm2) regions. These alterations in a region considered to be one of the most specialized in the visual process suggest a structural deficiency induced by congenital hypothyroidism, with a possible decrease in the visual acuity of the rat.

[Babkin's reflex in newborn: new reflexogenous zone]. / Reflexo de Babkin no recém-nascido: nova área reflexógena.

The authors have studied the hand-mouth reflex of Babkin on 422 newborns. 413 out of 422 newborns were considered normal. We have found responses not yet published such as accentuation of inferior limb flexion, trunk flexion, upper limb adduction, contraction of the mentalis muscle, contraction of the orbicular of the lips, extension of the inferior limb, extension of the pododactiles and cry. We obtained the same responses by pressing the infraclavicular space just near the esternal bone. We compared statistically: a) responses to the stimulus on the palm of the hand and on the new reflexogenous zone; b) responses presented by term and preterm newborns; c) responses of newborns less than 12 hours of age and more than 24 hours of age.

Effect of congenital hypothyroidism on cell density in the ganglion cell layer of the rat retina

The effect of congenital hypothyroidism on the visual system of Wistar rats was studied by determining neuron density in the retinal ganglion cell layer. Retinae of adult rats from mothers treated with propylthiouracil, 50 mg/day, starting on the l5th day of pregnancy (PTU group), and of adult rats from untreated mothers (control group) were examined. Retinae were prepared, and the neurons in the nasotemporal region located above the optic disc were counted. Hypothyroid rats showed a significant reduction in the retinal area (about 6.8 per cent), when compared to controls. The cell density in the retinal ganglion cell layer was significantly decreased in 6 PTUtreated compared to 5 control retinae in total (2,793 ñ 330 vs 3,704 ñ 662 neurons/mm2), nasal (3,031 ñ 580 vs 3,853 ñ 699 neurons/mm2) and temporal (2,555 ñ 156 vs 3,555 ñ 827 neurons/mm2) regions. These alterations in a region considered to be one of the most specialized in the visual process suggest a structural deficiency induced by congenital hypothyroidism, with a possible decrease in the vísual acuity of the rat.

Cytotoxic factor in the serum of diabetic rats and its increase during pregnancy.

Diabetic pregnancy is associated with a high incidence of fetal growth abnormalities which cannot be solely ascribed to fetal hyperglycaemia and hyperinsulinaemia. We therefore examined the possibility of other contributing factors using rats made diabetic with streptozotocin as the experimental model. Blood serum from virgin diabetic rats and, to a much greater extent, from pregnant diabetic rats inhibited [3H]thymidine incorporation by fetal lung cells in culture in a concentration- and time-dependent manner; cell number was also decreased. The cytotoxic activity of the serum was decreased by treatment of pregnant diabetic rats with insulin. Sera from non-diabetic rats and from rats at 6 h and 24 h after the injection of streptozotocin were not cytotoxic. The cytotoxic activity of diabetic rat serum was retained after dialysis and was not destroyed by heating it for 60 min at 60 degrees C. Diabetic rat serum antagonized the stimulatory effects of fetal bovine serum, insulin and insulin-like growth factors on thymidine incorporation by lung cells and inhibited corticosterone production by adrenal cells. Ultrafiltration of diabetic rat serum and high-performance gel permeation chromatography in phosphate buffer suggested that the molecular weight of the cytotoxic factor was approximately 40 kDa. However, gel permeation chromatography in 40% acetonitrile of the cytotoxic eluate from reversed-phase high-performance liquid chromatography using a C18 and C4 column revealed that the cytotoxic factor was a low molecular weight substance, which contained no amino acids. The apparent discrepancy in molecular weights using different separation procedures suggests that the cytotoxic factor is bound to serum proteins. The u.v. spectrum of this factor was different from those of ketone bodies but its exact chemical identity could not be established because of the scarcity of the material. It is suggested that the sera of pregnant diabetic rats and their fetuses contain a cytotoxic factor, which may contribute to fetal developmental abnormalities.

Metabolic adjustments during adaptation to high ambient temperature by preoptic-lesioned rats.

Metabolic adjustment was studied in male Wistar rats weighing 180-200 g with bilateral electrolytic lesions in the preoptic area which were acclimatized to a hot environment (34 degrees C, 30 rats) and to normal temperature (25 degrees C, 20 rats) for 60 days. Oxygen consumption at 34 degrees C and body weight were measured periodically. Preoptic-lesioned rats (PO rats) showed a reduction in metabolic rate (from 46.2 +/- 2 to 33 +/- 2 Cal/m2 per h, P less than 0.05) regardless of the temperatures to which they were adapted. Although the reduced metabolic rate of PO rats living at 25 degrees C or 34 degrees C could be an indicator of adaptation to heat, only the PO rats living at 25 degrees C showed a weight gain (101 +/- 13 g) similar to that observed for the sham-operated control (75 +/- 11 g). In fact, the PO rats living at 34 degrees C failed to increase their body weight during 60 days of exposure to heat. These data indicate that the preoptic area is essential to integrate the thermal input with the energy-linked metabolic process involved in adaptation to hot environments.

Metabolic adjustments during adaptation to high ambient temperature by preoptic-lesioned rats

Metabolic adjustment was studied in male Wistar rats weighing 180-200 g with bilateral electrolytic lesions in the preoptic area which were acclimatized to a hot envirnment (34-C, 30 rats) and to normal temperature (25-C, 20 rats) for 60 days. Oxygen consuption at 34-C and body weight were measured periodically. Preoptic-lesioned rats (POrats) showed a reduction in metabolic rate (from 46.2 ñ 2 to 33 ñ 2 Cal/m2 per h, P < 0.05) regardless of the temperatures to which they were adapted. Although the reduced metabolic rate of PO rats living at 25-C or 34-C could be an indicator of adaptation to heat, only the PO rats living at 25-C showed a weight gain (101 ñ 13 g) similar to that observed for the sham-operated control (75 ñ 11 g). In fact, the PO rats living at 34-C failed to increase their body weight during 60 days of exposure to heat. These data indicate that the preoptic area is essential to integrate the thermal imput with the energy-linked metabolic process involved in adaptation to hot environments

Metabolic adjustment induced by exposure to elevated ambient temperature is impaired in rats bearing lesions in the preoptic area.

Metabolic adjustment was studied in rats with bilateral electrolytic lesions in the preoptic area which were exposed to heat (34 degrees C) and to normal temperature (25 degrees C) for 60 days. The metabolic rate measured at neutral temperature (29 degrees C) in preoptic-lesioned rats living at 25 degrees or 34 degrees C was reduced to 80% the rate of sham-operated controls. The increase in metabolic rate induced by heat (30 min at 34 degrees or 37 degrees C) in preoptic-lesioned rats, living at 25 degrees C, was markedly reduced to 10% the rate of sham-operated controls living at 25 degrees C. In preoptic-lesioned rats, the increased metabolic rate induced by heat exposure (34 degrees or 37 degrees C) was impaired, regardless of the living ambient temperature (25 degrees or 34 degrees C) of the animal. These data demonstrate the participation of the preoptic area in heat-induced increased oxygen consumption and provide additional evidence for its role in the integration of thermal inputs with energy-linked metabolic processes.

Metabolic adjustment induced by exposure to elevated ambient temperature is impaired in rats bearingt lesions in the preoptic area

Metabolic adjustment was studied in rats with bilateral electrolytic lesions in the preoptic area which were exposed to heat (34-C) anda to normal temperature (25-C) for 60 days. The metabolic rate measured at neutral temperature (29-C) in preoptic-lesioned rats living at 25- or 34-C was reduced to 80% the rate of sham-operated controls. The increase in metabolic rate induced by heat (30 min at 34- or 37-C) in preoptic-lesioned rats, living at 25-C, was markedly reduced to 10% the rate of sham-operated controls living at 25-C. In preoptic-lesioned rats, the increased metabolic rate induced by heat exposure (34- or 37-C) was impaired, regardless of the living ambient temperature (25- or 34-C) of the animal. These data demonstrate the participation of the preoptic area in heat-induced invreased oxygen consumption and provide additional evidence for its role in the integration of thermal imputs with energy-linked metabolic processes

Efeito da temperatura ambiente na termogenese de ratos hipotireoideos. / Effect of environmental temperature on the thermogenesis of hypothyroid rats

Com a finalidade de avaliar o grau de participacao da tireoide nas respostas do animal a adaptacao ao calor, foram feitas medidas da taxa metabolica em ratos submetidos a tireoidectomia ou a lesoes eletroliticas da area PO/HA, mantida a temperatura ambiente de 25o. graus C., sendo as medidas do consumo de O2 realizadas durante a exposicao aguda a diferentes temperaturas ambientes. Os resultados mostraram que tanto o hipotireoidismo primario (TD), como o secundario (lesao de PO/HA), causam um aumento na zona de neutralidade termica do animal, com reducao da termogenese basal e maior tolerancia ao calor, indicando assim, que a reducao da atividade tireoidiana e o principal fator determinante da adaptacao ao calor em ratos