Prostaglandin F2α produced by rabbit renal slices is not a metabolite of prostaglandin E2

Slices of rabbit renal medulla and rabbit renal papilla were incubated with a mixture of [1-¹⁴C]-arachidonic acid and [5,6,8,9,11,12,14,15-³H]-arachidonic acid. In both tissues, comparison of the isotope ratios of the radioactive products with the isotope ratio of the added arachidonic indicated that: (a) there was no discernable isotope effect in the biosynthesis of prostaglandin E₂; (b) prostaglandin F₂α was formed by reduction of prostaglandin H₂ and not by reduction of prostaglandin E₂; and (c) most of the radioactive product arose from arachidonic acid that had been incorporated into the tissue and not from the direct action of cyclooxygenase on arachidonic acid in the medium.     

Trihalomethanes in desalinated water: Human exposure and risk analysis

Desalinated seawater is used to satisfy domestic water demands in many countries. The treated freshwater is blended with desalinated water to increase the water supply. The desalinated and blended water contains disinfection byproducts (DBPs), some of which may induce cancer risk to human. In this study, concentrations of trihalomethanes (THMs) in desalinated and blended water in Saudi Arabia were investigated, and human exposure and risk were predicted. The intakes of THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) were predicted to be 8.38 × 10^?5, 7.57 × 10^?5, 2.54 × 10^?5, and 4.32 × 10^?4 mg/kg-d, respectively. The overall cancer risk and hazard index were estimated to be 1.78 × 10^?5 (range: 7.40 × 10^?7–9.26 × 10^?5) and 3.49 × 10^?2 (range: 1.20 × 10^?3–2.34 × 10^?1), respectively. The probabilities of cancer risk exceeding the risk levels of 1 × 10^?6, 1 × 10^?5, and 5.0 × 10^?5 were 1.0, 0.775, and 0.012, respectively. The loss of disability adjusted life years (DALYs) was predicted to be 25.1 per year while the cancer risk represented 8.48 × 10^?7 DALY per person per year. The financial burden from such risk was estimated to be US$ 2.72 (range: US$ 2.52–2.91) million per year. The findings may assist in better understanding and reducing cancer risk from DBPs in desalinated and blended water.     

Rhizobial Association with Non-Legumes: Mechanisms and Applications

It has been known for more than a century that rhizobia can promote the growth of legumes through the formation of nitrogen-fixing nodules, but the interaction of rhizobia with non-legumes has been neglected as an experimental system. During the last couple of decades, work on rhizobial interaction with non-legumes has been done progressively and it has been demonstrated that rhizobia can associate with roots of non-legumes also, without forming true nodules, and can promote their growth by using one or more of the direct or indirect mechanisms of actions. Phytohormone production, secretion of other chemicals like lipo-chito-oligosaccharides (LCOs) and lumichrome, solubilization of precipitated phosphorus and mineralization of organic P, improvement in uptake of plant nutrients by altering root morphology, production of siderophores to meet the iron requirements of the plant under iron-stressed conditions and lowering of ethylene level through ACC deaminase enzyme, are some examples of the rhizobial mechanisms with direct positive effects on non-leguminous plant growth. Indirectly, rhizobia improve the growth of non-legumes through biocontrol of pathogens via antibiosis, parasitism or competition with pathogens for nutrients and space, by inducing systemic resistance in the host plant and through increasing root adhering soil by releasing exopolysaccarides which regulate the water movement and facilitate the root growth. However, no influence or even inhibitory effects of rhizobial inoculation on non-legumes has also been demonstrated in some cases. Plant growth promoting mechanisms of rhizobia and its practical application in non-legumes are the major focus of this review.