RESUMEN
Bean leaves (Phaseolus vulgaris L.) cv. Pérola were used to evaluate the water deficit effects in polar lipids composition and in the electric conductivity. The results showed that the water deficiency a effected in the electrolytes loss which increased gradually in response to water deficit. This suggested a compartimentalization loss, due to the structural cellular membranes elements degradation. Total lipids contents decreased by reason of the water stress action. The polyunsaturated fatty acid contents (linoleic and linolenic acids) suffered a decrease while saturated fatty acid (palmitic and stearic acids) increased. The imbalance in the fatty saturated/unsaturated acid relation led to a reduction in the unsaturation index. The electrolytes loss increase related whith the to polyunsaturated fatty acid contents reduction suggested a larger dehydrated plants vulnerability, leading to a consequent loss in the productivity.
No presente estudo, foram utilizadas plantas de feijão (Phaseolus vulgaris L.) cv. Pérola, com a finalidade de avaliar os efeitos do déficit hídrico na condutividade elétrica, nos teores de lipídios totais e de ácidos graxos. Os resultados evidenciaram importantes efeitos da deficiência hídrica como um aumento gradativo na perda de eletrólitos. O teor de ácidos graxos saturados (ácidos palmítico e esteárico) aumentou pela ação do estresse hídrico enquanto, o teor de ácidos graxos poliinsaturados (ácidos linoléico e linolênico) e o de lipídios sofreram decréscimo. O desequilíbrio na relação ácidos graxos saturados/insaturados conduziu a uma diminuição no índice de insaturação. O aumento na perda de eletrólitos associado à redução nos teores de lipídios polares e de ácidos graxos poliinsaturados sugere maior vulnerabilidade das plantas estressadas com conseqüente perda de produtividade.
RESUMEN
BACKGROUND: The stratom corneum lipids, responsible for the epidermal water bar rier, consist mainly of ceramides, cholesterol and free fatty acids. However, little has been studied about the effects of non-polar, polar and mixed organic solvents on the changes of the stratum corneum lipids bilayer. OBJECTIVE: We designed this study in order to investigate the effect of non-polar, polar and mixed organic solvents on the lipids bilayer in hairless mice. METHODS: Twenty four hairless mice were evenly divided into 4 groups; a control group, chloroform treated group, methanol treated group and mixed solvent(chloroform/methanol(2:1) ) treated gr oup. The changes in transepidermal water loss, as measured with an evaporimeter, were recorded after topical application of either chloroform, methanol or mixed solvents at 0, 3, 6, 12, 24 and 48 hours respectiveh. For electron microscopy, the skin samples taken from the mice of ea.:h group were t.rented with osmium tetroxide and ruthenium tetroxide after the treatment with each solvent. RESULTS: The results were as follows ; 1. From 0 to 24 hours after treatment with each solvent transepidermal water loss was significantly increased in the chloroform and the mixed solvent[chloroform/methanol(2:1)] treated groups, compared to the methanol treated group and control group(P<0.001). 2. 48 hours after treatment with each solvent, the differences in the values of transepidermal water loss in all groups were insignificant. 3. On electronmicroscopic examination, separation of intercellular lipid bilayers and a decrease in the numher of lamellar bodies were more severe in the chloroform treated and mixed solvent (chloroform/methanol(2:1)] treated groups than in the methanol treated group. Application of non-polar organic solvents, especially mixed solvents[chloroform/methanol(2:1)] resulted in an increase in transepidermal water loss and greater structural changes than with polar organic solvents. CONCLUSION: Our results suggest that non-polar lipids may play a more important role in the protection of water vaporization of the stratum corneum lipids barrier than polar lipids.