Synthesis and opioid activity of new fentanyl analogs

Three new fentanyl analogs (compounds 3-4-5) have been synthesized and evaluated for antinociceptive properties using the writhing test. The analgesic property of the active compound, N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl)] propenamide (compound 4), was tested using the hot plate test in mice. Its opioid agonistic activity was characterized using three isolated tissues: guinea pig ileum, mouse vas deferens, and rabbit vas deferens. Compound 4 was as effective as fentanyl or morphine and it showed less antinociceptive potency than fentanyl but it was more potent than morphine. The duration of the antinociception was similar to that of fentanyl. This compound inhibited the electrically evoked contractions of myenteric plexus-longitudinal muscle strips of guinea pig ileum and of mouse vas deferens but not those of rabbit vas deferens. These effects could be reversed by micro selective antagonists (naloxone and/or CTOP) but not by the delta selective antagonist naltrindole, thus indicating that the compound acted as a micro opioid agonist. Finally, the binding data confirmed that compound 4 had high affinity and selectivity for the micro-receptor.     

Altered Na+ and Li+ Homeostasis in Saccharomyces cerevisiae Cells Expressing the Bacterial Cation Antiporter NhaA

The bacterial Na⁺(Li⁺)/H⁺ antiporter NhaA has been expressed in the yeast Saccharomyces cerevisiae. NhaA was present in both the plasma membrane and internal membranes, and it conferred lithium but not sodium tolerance. In cells containing the yeast Ena1-4 (Na⁺, Li⁺) extrusion ATPase, the extra lithium tolerance conferred by NhaA was dependent on a functional vacuolar H⁺ ATPase and correlated with an increase of lithium in an intracellular pool which exhibited slow efflux of cations. In yeast mutants without (Na⁺, Li⁺) ATPase, lithium tolerance conferred by NhaA was not dependent on a functional vacuolar H⁺ ATPase and correlated with a decrease of intracellular lithium. NhaA was able to confer sodium tolerance and to decrease intracellular sodium accumulation in a double mutant devoid of both plasma membrane (Na⁺, Li⁺) ATPase and vacuolar H⁺ ATPase. These results indicate that the bacterial antiporter NhaA expressed in yeast is functional at both the plasma membrane and the vacuolar membrane. The phenotypes conferred by its expression depend on the functionality of plasma membrane (Na⁺, Li⁺) ATPase and vacuolar H⁺ ATPase.     

Influence of seasonal variation on the phenology and liriodenine content of Annona lutescens (Annonaceae)

Annona lutescens Saff. (Annonaceae) grows as a native tree in Chiapas, Mexico in Tropical Dry Forest habitat. Like most Annonaceae, it biosynthesizes benzylisoquinoline alkaloids, mostly liriodenine. To determine the influence of seasonal changes in the accumulation of liriodenine, the monthly variation of liriodenine content in roots, stems and leaves of mature and young trees was observed. These parts of young and mature A. lutescens trees were collected monthly over a 1 year period and the alkaloids were extracted; the liriodenine was quantified by high-resolution liquid chromatography. The phenological stages of the species were also assessed (leaf development, flowering and fruiting) using the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale. The analysis of both young and mature trees showed a significant increase in the liriodenine concentration occurs within roots during the dry season, which coincides with leaf fall. A significant decrease also occurred at the beginning of the rainy season (the period of leaf growth); the liriodenine content for the next rainy season did not reach the levels of the previous dry season. The climatic variation induced phenological and physiological changes in this species.     

The role of short-tongued insects in floral variation across the range of a style-dimorphic plant

Background and Aims

Heterostyly and related style polymorphisms are suitable model systems to evaluate the importance of functional pollinators in the maintenance of population variability. In Narcissus papyraceus different functional pollinators, incompatibility system and flower morphology have been proposed to influence the maintenance of polymorphism through their effect on disassortative mating. Here a test is done to find out if the visitation rate of long- versus short-tongued pollinators correlates with the morph ratio and if the latter is related to other flower traits of the species across its main geographic range.

Methods

Floral traits from 34 populations in the south-west of the Iberian Peninsula and in north-west Africa were measured, perianth variation was described and a comparison was made of allometric relationships between sex organs and floral tube. Correlations between pollinator guilds, stigma–anther separation of reciprocal morphs (our proxy for disassortative mating) and morph-ratio variation were analysed. Finally, the incompatibility system of the species in the northern and southern borders of its distribution are described.

Key Results

Flowers from southern populations were significantly larger than flowers from centre and northern populations. The abundance of short-styled plants decreased gradually with increasing distance from the core region (the Strait of Gibraltar), with these disappearing only in the northern range. Although there was a significant difference in stigma–anther separation among populations, morph ratio was not associated with reciprocity or floral tube length. Long-style morph frequency increased with short-tongued pollinator visitation rate. Populations from both edges of the distribution range were self-incompatible and within- and between-morph compatible.

Conclusions

The style morph ratio changed gradually, whereas perianth trait variation showed abrupt changes with two morphotypes across the range. The positive relationship between the visitation rate of short-tongued pollinators and the decrease of the short-style morph supports our initial hypothesis. The results highlight the importance of different pollinators in determining the presence of style polymorphism.     

Polar flagellum biogenesis in Aeromonas hydrophila

Mesophilic Aeromonas spp. constitutively express a single polar flagellum that helps the bacteria move to more favorable environments and is an important virulence and colonization factor. Certain strains can also produce multiple lateral flagella in semisolid media or over surfaces. We have previously reported 16 genes (flgN to flgL) that constitute region 1 of the Aeromonas hydrophila AH-3 polar flagellum biogenesis gene clusters. We identified 39 new polar flagellum genes distributed in four noncontiguous chromosome regions (regions 2 to 5). Region 2 contained six genes (flaA to maf-1), including a modification accessory factor gene (maf-1) that has not been previously reported and is thought to be involved in glycosylation of polar flagellum filament. Region 3 contained 29 genes (fliE to orf29), most of which are involved in flagellum basal body formation and chemotaxis. Region 4 contained a single gene involved in the motor stator formation (motX), and region 5 contained the three master regulatory genes for the A. hydrophila polar flagella (flrA to flrC). Mutations in the flaH, maf-1, fliM, flhA, fliA, and flrC genes, as well as the double mutant flaA flaB, all caused loss of polar flagella and reduction in adherence and biofilm formation. A defined mutation in the pomB stator gene did not affect polar flagellum motility, in contrast to the motX mutant, which was unable to swim even though it expressed a polar flagellum. Mutations in all of these genes did not affect lateral flagellum synthesis or swarming motility, showing that both A. hydrophila flagellum systems are entirely distinct.     

Engineering increased vitamin C levels in plants by overexpression of a D-galacturonic acid reductase

L-Ascorbic acid (vitamin C) in fruits and vegetables is an essential component of human nutrition. Surprisingly, only limited information is available about the pathway(s) leading to its biosynthesis in plants. Here, we report the isolation and characterization of GalUR, a gene from strawberry that encodes an NADPH-dependent D-galacturonate reductase. We provide evidence that the biosynthesis of L-ascorbic acid in strawberry fruit occurs through D-galacturonic acid, a principal component of cell wall pectins. Expression of GalUR correlated with changing ascorbic acid content in strawberry fruit during ripening and with variations in ascorbic acid content in fruit of different species of the genus Fragaria. Reduced pectin solubilization in cell walls of transgenic strawberry fruit with decreased expression of an endogenous pectate lyase gene resulted in lower ascorbic acid content. Overexpression of GalUR in Arabidopsis thaliana enhanced vitamin C content two- to threefold, demonstrating the feasibility of engineering increased vitamin C levels in plants using this gene.     

Ellagic acid protects from myelin-associated sphingolipid loss in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE), the most common model for multiple sclerosis, is characterized by inflammatory cell infiltration into the central nervous system and demyelination. Previous studies have demonstrated that administration of some polyphenols may reduce the neurological alterations of EAE. In this work, we show that ellagic acid, a polyphenolic compound, is beneficial in EAE, most likely through stimulation of ceramide biosynthesis within the brain. EAE was induced in Lewis rats by injection of guinea-pig spinal cord tissue along with Freund's complete adjuvant containing Mycobacterium tuberculosis. Clinical signs first appeared at day 8 post-immunization and reached a peak within 3?days, coincident with reduction of myelin basic protein (MBP) in the cortex. Sphingolipids, the other major components of myelin, also decreased at the acute phase of EAE, both in the cerebral cortex and in the spinal cord. In rats receiving ellagic acid in the drinking water from 2?days before immunization, the onset of the disease was delayed and clinical signs were reduced. This amelioration of clinical signs was accompanied by sustained levels of both MBP and sphingolipid in the cortex, without apparent changes in infiltration of inflammatory CD3+ T-cells, microglial activation, or weight loss, which together suggest a neuroprotective effect of ellagic acid. Finally, in glioma and oligodendroglioma cells we demonstrate that urolithins, the ellagic acid metabolites that circulate in plasma, stimulate the synthesis of ceramide. Together these data suggest that ellagic acid consumption protects against demyelination in rats with induced EAE, likely by a mechanism involving sphingolipid synthesis.     

Seasonal variations in food web dynamics of floodplain lakes with contrasting hydrological connectivity in the Southern Gulf of Mexico

Hydrobiologia - Floodplains are some of the most productive and diverse ecosystems on Earth. The Usumacinta River Basin, in the Southern Gulf of Mexico, hosts several floodplain lakes, whose...     

Identification of the phosphoglycerate dehydrogenase isoform EDA9 as the essential gene for embryo and male gametophyte development in Arabidopsis

Three different pathways of serine (Ser) biosynthesis have been described in plants: the Glycolate pathway, which is part of the Photorespiratory pathway, and 2 non-Photorespiratory pathways, the Glycerate and the Phosphorylated pathways. The Phosphorylated Pathway of Ser Biosynthesis (PPSB) has been known to exist since the 1950s, but its biological relevance was not revealed until quite recently when the last enzyme of the pathway, the Phosphoserine Phosphatase, was functionally characterized. In the associated study¹, we characterized a family of genes coding for putatite phosphoglycerate dehydrogenases (PGDH, 3-PGDH, and EDA9), the first enzyme of the PPSB. A metabolomics study using overexpressing plants indicated that all PGDH family genes were able to regulate Ser homeostasis but only lacking of EDA9 expression caused drastic developmental defects. We provided genetic and molecular evidence for the essential role of EDA9 for embryo and pollen development. Here, some new insights into the physiological/molecular function of PPSB and Ser are presented and discussed.