Opioids are a group of analgesic agents commonly used in clinical practice. There are three classical opioid receptors (DOP, KOP and MOP), while the novel NOP receptor is considered to be a non-opioid branch of the opioid receptor family. Opioids can act at these receptors as agonists, antagonists or partial agonists. Opioid agonists bind to G-protein coupled receptors to cause cellular hyperpolarisation. Most clinically relevant opioid analgesics bind to MOP receptors in the central and peripheral nervous system in an agonist manner to elicit analgesia. Opioids may also be classified according to their mode of synthesis into alkaloids, semi-synthetic and synthetic compounds.

Transgenic Brassica napus plants overexpressing AtNHX1, a vacuolar Na ؉ ͞H ؉ antiport from Arabidopsis thaliana, were able to grow, flower, and produce seeds in the presence of 200 mM sodium chloride. Although the transgenic plants grown in high salinity accumulated sodium up to 6% of their dry weight, growth of the these plants was only marginally affected by the high salt concentration. Moreover, seed yields and the seed oil quality were not affected by the high salinity of the soil. Our results demonstrate the potential use of these transgenic plants for agricultural use in saline soils. Our findings, showing that the modification of a single trait significantly improved the salinity tolerance of this crop plant, suggest that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated.A gricultural productivity is severely affected by soil salinity, and the damaging effects of salt accumulation in agricultural soils have influenced ancient and modern civilizations. The detrimental effects of salt on plants are a consequence of both a water deficit that results from the relatively high solute concentrations in the soil and a Na ϩ -specific stress resulting from altered K ϩ ͞Na ϩ ratios and Na ϩ ion concentrations that are inimical to plants. The alteration of ion ratios in the plant is caused by the influx of Na ϩ through pathways that function in the acquisition of K ϩ (1).Wild plants that tolerate salt and grow in saline environments have high intracellular salt levels. A major component of the osmotic adjustment in these cells is accomplished by ion uptake. The utilization of inorganic ions for osmotic adjustment would suggest that salt-tolerant plants must be able to tolerate high levels of salts within their cells. However, enzymes extracted from these plants show high sensitivity to salt (2, 3), suggesting that these plants are able to keep Na ϩ away from the cytosol. Plants can use three strategies for the maintenance of a low Na ϩ concentration: sodium exclusion, sodium compartmentation, and sodium secretion. Sodium transport out of the cell can be accomplished by the operation of plasma membrane-bound Na ϩ ͞H ϩ antiports. Biochemical evidence for the operation of plasma membrane Na ϩ ͞H ϩ antiports (4) and the characterization of SOS1, a putative plasma membrane Na ϩ ͞H ϩ antiport from Arabidopsis thaliana (5), have been reported. Transport mechanisms can also actively move ions across the tonoplast into the vacuole, removing the potentially harmful ions from the cytosol. These ions, in turn, act as an osmoticum within the vacuole, which then maintain water flow into the cell (3). The presence of large, acidic-inside, tonoplast-bound vacuoles in plant cells allows the efficient compartmentation of sodium into the vacuole, through the operation of vacuolar Na ϩ ͞H ϩ antiports (6, 7).The overexpression of AtNHX1, a vacuolar Na ϩ ͞H ϩ antiport from A. thaliana, in Arabidopsis (7) and tomato (8) plants allo...

Sensitivity of the photosynthetic thylakoid membranes to thermal stress was investigated in the psychrophilic Antarctic alga Chlamydomonas subcaudata. C. subcaudata thylakoids exhibited an elevated heat sensitivity as indicated by a temperature-induced rise in F(o) fluorescence in comparison with the mesophilic species, Chlamydomonas reinhardtii. This was accompanied by a loss of structural stability of the photosystem (PS) II core complex and functional changes at the level of PSI in C. reinhardtii, but not in C. subcaudata. Lastly, C. subcaudata exhibited an increase in unsaturated fatty acid content of membrane lipids in combination with unique fatty acid species. The relationship between lipid unsaturation and the functioning of the photosynthetic apparatus under elevated temperatures is discussed.

Potent adenosine hA2A receptor antagonists are often accompanied by poor aqueous solubility, which presents issues for drug development. Herein we describe the early exploration of the structure-activity relationships of a lead pyrimidin-4-yl acetamide series to provide potent and selective 2-amino-N-pyrimidin-4-yl acetamides as hA2A receptor antagonists with excellent aqueous solubility. In addition, this series of compounds has demonstrated good bioavailability and in vivo efficacy in a rodent model of Parkinson's disease, despite having reduced potency for the rat A2A receptor versus the human A2A receptor.