Optimum fertilization management is an important technique to alleviate the adverse effects of salinity stress on plants. A pot experiment was conducted to evaluate the ameliorative role of inorganic phosphorus (P) and organic P sources on wheat grown under salt stress in three soil types deficient in available P. Wheat (Triticum aestivum L. cv. Shakha 93) was grown on alluvial, sandy and calcareous soils at salinity levels of 4, 8 and 12 dS/m of saturated paste extract (ECe) and supplied with a constant rate of 30 mg P2O5/kg soil as superphosphate (SP), cattle manure (CM) and a 1:1 mixture of SP and CM. The results revealed that plants grown on the sandy soil were more susceptible to the adverse effects of salinity than those planted on the alluvial one, especially at zero P. Plants grown on the calcareous soil were moderately affected. The varying soil type caused significant differences in the aboveground biomass and the uptake of N, K, P and Zn. It was obvious that P ameliorated wheat growth under salt stress, and this role was greater under moderate and high salinity. The increases in N, P, K and Zn uptake driven by P application were more conspicuous in the sandy and calcareous soils. The results also indicated that the combined application of inorganic and organic P sources surpassed that of either when applied alone on all soil types and salinity levels.
Hydrogen sulphide (H 2 S) is a gas signaling molecule which is produced endogenously from L-cysteine via the enzymes cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). H 2 S may mediate hypoxic responses in vascular smooth muscle. H 2 S also appears to be a signaling molecule in mammalian nonvascular smooth muscle. Hypoxia is associated with pre-eclampsia where poor placental function can reduce the supply of oxygen and nutrients to the fetus resulting in intrauterine growth restriction (IUGR) and other placental dysfunctions. Hypoxia can also bring about other pre-eclamptic features such as the release of proinflammatory cytokines and oxidative stress. Hypoxic conditions can also reduce the uteroplacental perfusion, which may lead to inflammatory conditions i.e. oxidative stress. However, there are no reports to date on the production of H 2 S in reproductive tissues and the possible role of hydrogen sulphide in reproduction has not yet been fully investigated. It has been previously demonstrated that hydrogen sulphide relaxes uterine smooth muscle in vitro. We investigated the endogenous production of H 2 S in rat intrauterine tissues and the effect of NO and low oxygen condition on H 2 S production in intrauterine tissues. The production of H 2 S in rat intrauterine tissues was measured in vitro using a standard technique. The expression of CBS and CSE was also investigated in rat intrauterine tissues via western blotting. Furthermore, the effects of nitric oxide (NO) and low oxygen conditions on the production rates of hydrogen sulphide were investigated. The order of H 2 S production rates for rat tissues were: liver (488±28.9 nM/min/g) > uterus (310±36.7 nM/min/g) > fetal membranes (88.2±3.8 nM/min/g)> placenta (42.7± 6.8 nM/min/g). Under the effect of NO donor, NO significantly increased H 2 S production in rat fetal membranes only (from 88.2±3.8 nM/min/g to 103.2±7.4 nM/min/g). Under low oxygen conditions, production of H 2 S was significantly increased compared to room air oxygen conditions for rat liver (from 422±31.6 nM/min/g to 583±38.7 nM/min/g), uterus (from 328±11.8 nM/min/g to 5913±21.8 nM/min/g) and fetal membranes (from 78.2±9.1 to 189±17.1) , but not rat placenta. Western blotting detected the expression of CBS and CSE in all rat intrauterine tissues. Rat intrauterine tissues produce H 2 S in vitro possibly via CBS and CSE enzymes.
Bull. Egypt. Soc. Physiol. Sci. 29 (2) 2009El-Sekelly et al.
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