Chemical composition of salt-marsh plants from Ynys Môn (Anglesey): the concept of physiotypes

Abstract The chemical compositions of a number of halophytes from salt marshes on Ynys Môn (Anglesey), Wales, and of some related mesophytes and sand dune plants have been determined. Analyses of the inorganic ions broadly confirmed the existence of a characteristic chemical composition of many monoco-tyledonous salt-marsh plants in that they contain high levels of potassium and relatively low levels of sodium. In contrast to most dicotyledonous halophytes, especially members of the Chenopodiacease, the monocots restrict the entry of inorganic ions and use high levels of soluble sugars to maintain an adequate solute potential. Low calcium levels were not found to be a feature of these plants, as was previously reported. The large amounts of sugars found in the monocotyle-donous plants suggested that they must be located mainly in the vacuoles, in contrast to glycinebetaine which is thought to accumulate principally in the cytoplasm of the salt accumulating Chenopodiaceae. The monocotyledonous halophytes which accumulate proline differ from the normal monocotyledonous physiotype in the accumulation of larger quantities of sodium. Triglochin maritima is one species of this type, and Puccinellia maritima a less extreme example. Spartina spp. accumulating glycinebetaine and β-dimethyl-sulphoniopropionate also have unusually high inorganic ion contents for monocots. Several salt marsh plants contained large quantities of amino acids other than proline. As with ionic composition, the nature of the organic solutes broadly followed taxonomic lines. The usefulness of the physiotype concept is discussed.     

Synthesis and GABA(A) receptor activity of oxygen-bridged neurosteroid analogs

Three analogs of neuroactive steroids were prepared (4-6) in which 1,11- or 11,19-oxygen bridges give a constrained conformation. Their 3D structures were obtained by ab initio calculations and in the case of 3alpha-hydroxy-11,19-epoxypregn-4-ene-20-one (4), confirmed by X-ray analysis. Biological activity of the synthetic steroids was assayed in vitro using t-[(3)H]butylbicycloorthobenzoate as radiolabeled ligand for the GABA(A) receptor. The activity of compound 4 was similar to that of allopregnanolone (1). 1alpha,11alpha-Epoxypregnanolone (6) was more active than pregnanolone (2).     

Acidic heteroxylans from medicinal plants and their anti-ulcer activity

Xylans are the main hemicelluloses found in higher plants, and are often present in phytotherapic medicines. An acidic heteroxylan was obtained from Maytenus ilicifolia leaves by hot 10% aqueous KOH extraction. This was subjected to freeze-thawing process, giving insoluble and soluble fractions and the latter treated with Fehling solution. Its insoluble fraction (MI-HX) was further examined. The acidic heteroxylan gave xylose, galactose, glucose, and 4-O-methylglucuronic acid in a 76:6:9:9 molar ratio and methylation analyses and ¹³C NMR spectroscopy showed its main chain consists of 4-O-linked β-d-Xylp units. This polysaccharide and another acidic heteroxylan from Phyllanthus niruri had anti-ulcer activity and were able to reduce gastric lesions induced by ethanol by 65% and 78%, with ED₅₀ = 40.0 and 20.4 mg/kg, each respectively. These results suggest that this class of polysaccharide has a protective anti-ulcer effect, and that there is a relation between its chemical structure and biological function.     

Prevention and treatment of respiratory syncytial virus bronchiolitis and postbronchiolitic wheezing

Growth factors mediate tissue interactions and regulate a variety of cellular functions that are critical for normal lung development and homeostasis. Besides their involvement in lung pattern formation, growth and cell differentiation during organogenesis, these factors have been also implicated in modulating injury-repair responses of the adult lung. Altered expression of growth factors, such as transforming growth factor β1, vascular endothelial growth factor and epidermal growth factor, and/or their receptors, has been found in a number of pathological lung conditions. In this paper, we discuss the dual role of these molecules in mediating beneficial feedback responses or responses that can further damage lung integrity; we shall also discuss the basis for their prospective use as therapeutic agents.     

Sea‐level variations have influenced the demographic history of estuarine and freshwater fishes of the coastal plain of Paraná, Brazil

This study surveyed the mitochondrial haplotype diversity of nine freshwater fish species and two estuarine–marine species from the coastal basins and drainages of the highland plateaus of Paraná, Brazil. Portions of the cytochrome b gene or the control region were sequenced. The demographic history of each species was inferred using the Bayesian skyline method, mismatch distribution analysis and statistical neutrality tests. Demographic reconstruction analyses revealed a single pattern of variation in the effective population size (N_e) among species. No dramatic changes in N_e were detected in upland species. By contrast, evidence of population expansion over the past 200 000 years was detected in all coastal plain and estuarine species. These findings correspond to periods of low sea‐level (regressions) followed by a rapid increase in the sea‐level by >100 m. The resulting reconnections and subsequent fragmentation and isolation between the estuarine and freshwater bodies were putatively relevant to the historical demography of the fish species in these areas.     

The role of the P2X7 receptor in murine cutaneous leishmaniasis: aspects of inflammation and parasite control

Leishmania amazonensis is the etiological agent of diffuse cutaneous leishmaniasis. The immunopathology of leishmaniasis caused by L. amazonensis infection is dependent on the pathogenic role of effector CD4⁺ T cells. Purinergic signalling has been implicated in resistance to infection by different intracellular parasites. In this study, we evaluated the role of the P2X7 receptor in modulating the immune response and susceptibility to infection by L. amazonensis. We found that P2X7-deficient mice are more susceptible to L. amazonensis infection than wild-type (WT) mice. P2X7 deletion resulted in increased lesion size and parasite load. Our histological analysis showed an increase in cell infiltration in infected footpads of P2X7-deficient mice. Analysis of the cytokine profile in footpad homogenates showed increased levels of IFN-γ and decreased TGF-β production in P2X7-deficient mice, suggesting an exaggerated pro-inflammatory response. In addition, we observed that CD4⁺ and CD8⁺ T cells from infected P2X7-deficient mice exhibit a higher proliferative capacity than infected WT mice. These data suggest that P2X7 receptor plays a key role in parasite control by regulating T effector cells and inflammation during L. amazonensis infection.