Feather‐degrading bacteria,uropygial gland size and feather quality in House Sparrows Passer domesticus

Feathers are dead integumentary structures that are prone to damage and thus show gradual degradation over the course of a year. This loss of quality might have negative fitness consequences. Feather‐degrading bacteria are some of the most prevalent feather‐degrading organisms, yet the relationship between feather‐degrading bacteria load and flight feather quality has rarely been assessed. We studied this relationship in free‐living House Sparrows during breeding and non‐breeding annual lifecycle stages. We also considered the size of the uropygial gland, given the antimicrobial function of its secretions, and the effect of body condition. The number of feather holes was positively associated with feather‐degrading bacteria load and was negatively related to uropygial gland size and body condition during the breeding season in both sexes. In the non‐breeding season we found the same relationships, but only in females. The degree of feather wear was unrelated to any of the variables measured during the breeding season, whereas it was negatively associated with uropygial gland size and positively with feather‐degrading bacteria load in the non‐breeding season, but only in females. Our results suggest that feather‐degrading bacteria may induce the formation of feather holes, but play only a minor role in the abrasion of flight feathers.     

Vascular endothelial growth factor signals endothelial cell production of nitric oxide and prostacyclin through flk-1/KDR activation of c-Src.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell-specific mitogen that promotes angiogenesis, vascular hyperpermeability, and vasodilation by autocrine mechanisms involving nitric oxide (NO) and prostacyclin (PGI(2)) production. These experiments used immunoprecipitation and immunoassay procedures to characterize the signaling pathways by which VEGF induces NO and PGI(2) formation in cultured endothelial cells. The data showed that VEGF stimulates complex formation of the flk-1/kinase-insert domain-containing receptor (KDR) VEGF receptor with c-Src and that Src activation is required for VEGF induction of phospholipase C gamma1 activation and inositol 1,4,5-trisphosphate formation. Reporter cell assays showed that VEGF promotes a approximately 50-fold increase in NO formation, which peaks at 5-20 min. This effect is mediated by a signaling cascade initiated by flk-1/KDR activation of c-Src, leading to phospholipase C gamma1 activation, inositol 1,4,5-trisphosphate formation, release of [Ca(2+)](i) and nitric oxide synthase activation. Immunoassays of VEGF-induced 6-keto prostaglandin F(1alpha) formation as an indicator of PGI(2) production revealed a 3-4-fold increase that peaked at 45-60 min. The PGI(2) signaling pathway follows the NO pathway through release of [Ca(2+)](i), but diverges prior to NOS activation and also requires activation of mitogen-activated protein kinase. These results suggest that NO and PGI(2) function in parallel in mediating the effects of VEGF.     

The effect of triacontanol on micropropagation of balm, Melissa officinalis L.

 Triacontanol, a long-chain primary alcohol was found to be an effective growth regulator in the micropropagation of balm, Melissa officinalis. In both the multiplication and the rooting phase, concentrations of 2, 5, 10 and 20 μg triacontanol per liter were applied. After 4 weeks of culture, the fresh weight of shoots was measured in the multiplication phase and root formation, photosynthetic activity, chlorophyll content and the fresh and dry weights of shoots were analyzed in the root induction phase. In the multiplication phase, 5 μg/l triacontanol was found to be the optimal concentration, while in the rooting phase 2 μg/l was the most effective. Triacontanol increased the number and length of roots, and it enhanced shoot growth, fresh weight, and the chlorophyll content, but it had no effect on the dry weight and the photosynthetic activity of the plants. Results of our work demonstrate that triacontanol can be applied as an effective growth regulator in the tissue culture of balm. Received: 3 December 1997 / Revised: 24 February 1998 / Accepted: 26 February 1999     

Macroinvertebrate community traits and nitrate removal in stream sediments

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The Delta fbpA mutant derived from Mycobacterium tuberculosis H37Rv has an enhanced susceptibility to intracellular antimicrobial oxidative mechanisms, undergoes limited phagosome maturation and activates macrophages and dendritic cells

Mycobacterium tuberculosis H37Rv (Mtb) excludes phagocyte oxidase (phox) and inducible nitric oxide synthase (iNOS) while preventing lysosomal fusion in macrophages (MPhis). The antigen 85A deficient (Delta fbpA) mutant of Mtb was vaccinogenic in mice and the mechanisms of attenuation were compared with MPhis infected with H37Rv and BCG. Delta fbpA contained reduced amounts of trehalose 6, 6, dimycolate and induced minimal levels of SOCS-1 in MPhis. Blockade of oxidants enhanced the growth of Delta fbpA in MPhis that correlated with increased colocalization with phox and iNOS. Green fluorescent protein-expressing strains within MPhis or purified phagosomes were analysed for endosomal traffick with immunofluorescence and Western blot. Delta fbpA phagosomes were enriched for rab5, rab11, LAMP-1 and Hck suggesting enhanced fusion with early, recycling and late endosomes in MPhis compared with BCG or H37Rv. Delta fbpA phagosomes were thus more mature than H37Rv or BCG although, they failed to acquire rab7 and CD63 preventing lysosomal fusion. Finally, Delta fbpA infected MPhis and dendritic cells (DCs) showed an enhanced MHC-II and CD1d expression and primed immune T cells to release more IFN-gamma compared with those infected with BCG and H37Rv. Delta fbpA was thus more immunogenic in MPhis and DCs because of an enhanced susceptibility to oxidants and increased maturation.     

Genome size dynamics in Artemisia L. (Asteraceae): following the track of polyploidy

Polyploidy is a key factor in the evolution of higher plants and plays an important role in the variation of plant genomes, leading to speciation in some cases. During polyploidisation, different balancing processes take place at the genomic level that can promote variation in nuclear DNA content. We estimated genome size using flow cytometry in 84 populations of 67 Artemisia species and one population of Crossostephium chinense. A total of 73 sequences of nrDNA ITS and 3′‐ETS were newly generated and analysed, together with previously published sequences, to address the evolution of genome size in a phylogenetic framework. Differences in 2C values were detected among some lineages, as well as an increase of genome size heterogeneity in subgenera whose phylogenetic relationships are still unclear. We confirmed that the increase in 2C values in Artemisia polyploids was not proportional to ploidy level, but 1Cx genome size tended to decrease significantly when high ploidy levels were reached. The results lead us to hypothesise that genome size in polyploids tends to a maximum as it follows saturation behaviour, in agreement with the Michaelis–Menten model. We tested different arithmetic functions with our dataset that corroborated a non‐linear relationship of genome size increase in polyploids, allowing us to suggest a theoretical upper limit for the DNA content of this genus.     

Antimicrobial activity of the acidophilic eukaryotic microalga Coccomyxa onubensis

Extremophilic microalgae are unexplored as a source of pharmaceuticals despite the fact that its biomass can be produced at large scale with low risk of contamination. A significant amount of antimicrobial activity was produced by extracts obtained from the eukaryotic acidophilic microalgae Coccomyxa onubensis in non‐polar solvents, such as hexane, diethyl ether, and chloroform or in weakly polar solvents, such as dichloromethane, against Gram‐negative and Gram‐positive bacteria, and also the yeast Candida albicans. The most effective activity was shown by chloroform extract against Escherichia coli S, Salmonella enterica, and Proteus mirabilis; hexane extract against P. mirabilis, Sa. enterica, and Ca. albicans; dichloromethane extract against Sa. enterica or diethyl ether extract against E. coli S and the Gram‐positive Staphylococcus aureus MB. The lowest minimum inhibitory concentration values were recorded against E. coli S (305 μg mL ^?1) and P. mirabilis (153 μg mL ^?1) (using chloroform extract) and against P. mirabilis (106 μg mL^?1) (using hexane extract). Fatty acids, but not carotenoids, seem to be involved in the antimicrobial activity of this microalga. However, further biochemical and biotechnological studies must be conducted in order to characterize and purify the bioactive principles from Co. onubensis for assessing its potential as a pharmaceutical source and feasibility of production.