Antioxidant Capacity of Ugni molinae Fruit Extract on Human Erythrocytes: An In Vitro Study

Ugni molinae is an important source of molecules with strong antioxidant activity widely used as a medicinal plant in Southern Chile–Argentina. Total phenol concentration from its fruit extract was 10.64 ± 0.04 mM gallic acid equivalents. Analysis by means of HPLC/MS indicated the presence of the anthocyanins cyanidin and peonidin, and the flavonol quercitin, all in glycosylated forms. Its antioxidant properties were assessed in human erythrocytes in vitro exposed to HClO oxidative stress. Scanning electron microscopy showed that HClO induced an alteration in erythrocytes from a normal shape to echinocytes; however, this change was highly attenuated in samples containing U. molinae extracts. It also had a tendency in order to reduce the hemolytic effect of HClO. In addition, X-ray diffraction experiments were performed in dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine bilayers, classes of lipids preferentially located in the outer and inner monolayers, respectively, of the human erythrocyte membrane. It was observed that U. molinae only interacted with DMPC. Results by fluorescence spectroscopy on DMPC large unilamellar vesicles and isolated unsealed human erythrocyte membranes also showed that it interacted with the erythrocyte membrane and DMPC. It is possible that the location of U. molinae components into the membrane outer monolayer might hinder the diffusion of HClO and of free radicals into cell membranes and the consequent decrease of the kinetics of free radical reactions.     

Role for the TRPV1 Channel in Insulin Secretion from Pancreatic Beta Cells

Transient receptor potential channels have been put forward as regulators of insulin secretion. A role for the TRPV1 ion channel in insulin secretion has been suggested in pancreatic beta cell lines. We explored whether TRPV1 is functionally expressed in RINm5F and primary beta cells from neonate and adult rats. We examined if capsaicin could activate cationic non-selective currents. Our results show that TRPV1 channels are not functional in insulin-secreting cells, since capsaicin did not produce current activation, not even under culture conditions known to induce the expression of other ion channels in these cells. Although TRPV1 channels seem to be irrelevant for the physiology of isolated beta cells, they may play a role in glucose homeostasis acting through the nerve fibers that regulate islet function. At the physiological level, we observed that Trpv1 ^?/? mice presented lower fasting insulin levels than their wild-type littermates, however, we did not find differences between these experimental groups nor in the glucose tolerance test or in the insulin secretion. However, we did find that the Trpv1 ^?/? mice exhibited a higher insulin sensitivity compared to their wild-type counterparts. Our results demonstrate that TRPV1 does not contribute to glucose-induced insulin secretion in beta cells as was previously thought, but it is possible that it may control insulin sensitivity.     

Unveiling the Intracellular Survival Gene Kit of Trypanosomatid Parasites

Trypanosomatids are unicellular protozoans of medical and economical relevance since they are the etiologic agents of infectious diseases in humans as well as livestock. Whereas Trypanosoma cruzi and different species of Leishmania are obligate intracellular parasites, Trypanosoma brucei and other trypanosomatids develop extracellularly throughout their entire life cycle. After their genomes have been sequenced, various comparative genomic studies aimed at identifying sequences involved with host cell invasion and intracellular survival have been described. However, for only a handful of genes, most of them present exclusively in the T. cruzi or Leishmania genomes, has there been any experimental evidence associating them with intracellular parasitism. With the increasing number of published complete genome sequences of members of the trypanosomatid family, including not only different Trypanosoma and Leishmania strains and subspecies but also trypanosomatids that do not infect humans or other mammals, we may now be able to contemplate a slightly better picture regarding the specific set of parasite factors that defines each organism''s mode of living and the associated disease phenotypes. Here, we review the studies concerning T. cruzi and Leishmania genes that have been implicated with cell invasion and intracellular parasitism and also summarize the wealth of new information regarding the mode of living of intracellular parasites that is resulting from comparative genome studies that are based on increasingly larger trypanosomatid genome datasets.     

Targeted Disruption of an EH‐domain Protein Endocytic Complex,Pan1‐End3

Pan1 is a multi‐domain scaffold that enables dynamic interactions with both structural and regulatory components of the endocytic pathway. Pan1 is composed of Eps15 Homology (EH) domains which interact with adaptor proteins, a central region that is responsible for its oligomerization and C‐terminal binding sites for Arp2/3, F‐actin, and type‐I myosin motors. In this study, we have characterized the binding sites between Pan1 and its constitutive binding partner End3, another EH domain containing endocytic protein. The C‐terminal End3 Repeats of End3 associate with the N‐terminal part of Pan1's central coiled‐coil region. These repeats appear to act independently of one another as tandem, redundant binding sites for Pan1. The end3‐1 allele was sequenced, and corresponds to a C‐terminal truncation lacking the End3 Repeats. Mutations of the End3 Repeats highlight that those residues which are identical between these repeats serve as contact sites for the interaction with Pan1.      

Lung clearance index in adults with non-cystic fibrosis bronchiectasis

Background

Lung clearance index (LCI) is a measure of abnormal ventilation distribution derived from the multiple breath inert gas washout (MBW) technique. We aimed to determine the clinical utility of LCI in non-CF bronchiectasis, and to assess two novel MBW parameters that distinguish between increases in LCI due to specific ventilation inequality (LCI_vent) and increased respiratory dead space (LCI_ds).

Methods

Forty-three patients with non-CF bronchiectasis and 18 healthy control subjects underwent MBW using the sulphur hexafluoride wash-in technique, and data from 40 adults with CF were re-analysed. LCI_vent and LCI_ds were calculated using a theoretical two-compartment lung model, and represent the proportional increase in LCI above its ideal value due to specific ventilation inequality and increased respiratory dead space, respectively.

Results

LCI was significantly raised in patients with non-CF bronchiectasis compared to healthy controls (9.99 versus 7.28, p < 0.01), and discriminated well between these two groups (area under receiver operating curve = 0.90, versus 0.83 for forced expiratory volume in one second [% predicted]). LCI, LCI_vent and LCI_ds were repeatable (intraclass correlation coefficient > 0.75), and correlated significantly with measures of spirometric airflow obstruction.

Conclusion

LCI is repeatable, discriminatory, and is associated with spirometric airflow obstruction in patients with non-CF bronchiectasis. LCI_vent and LCI_ds are a practical and repeatable alternative to phase III slope analysis and may allow a further level of mechanistic information to be extracted from the MBW test in patients with severe ventilation heterogeneity.     

New frontiers in competition for pollination

Background

Co-flowering plant species frequently share pollinators. Pollinator sharing is often detrimental to one or more of these species, leading to competition for pollination. Perhaps because it offers an intriguing juxtaposition of ecological opposites – mutualism and competition – within one relatively tractable system, competition for pollination has captured the interest of ecologists for over a century.

Scope

Our intent is to contemplate exciting areas for further work on competition for pollination, rather than to exhaustively review past studies. After a brief historical summary, we present a conceptual framework that incorporates many aspects of competition for pollination, involving both the quantity and quality of pollination services, and both female and male sex functions of flowers. Using this framework, we contemplate a relatively subtle mechanism of competition involving pollen loss, and consider how competition might affect plant mating systems, overall reproductive success and multi-species interactions. We next consider how competition for pollination might be altered by several emerging consequences of a changing planet, including the spread of alien species, climate change and pollinator declines. Most of these topics represent new frontiers whose exploration has just begun.

Conclusions

Competition for pollination has served as a model for the integration of ecological and evolutionary perspectives in the study of species interactions. Its study has elucidated both obvious and more subtle mechanisms, and has documented a range of outcomes. However, the potential for this interaction to inform our understanding of both pure and applied aspects of pollination biology has only begun to be realized.Key words: Alien plants, climate change, competition for pollination, facilitation, mating system, mechanism, Lythrum, Mimulus, pollinator visitation, sexual function, invasive species, pollen loss     

Genetic variability of two populations of Pseudoplatystoma reticulatum from the Upper Paraguay River Basin

Catfishes of the genus Pseudoplatystoma are very important species due to both their high commercial value and their ecological role as voracious predators. They undertake lengthy migratory movements during their life-cycle, this including reproductive migration which occurs from October to December in the rainy season. In the present study, seven microsatellite loci were analyzed to access genetic variability in two samples of P. reticulatum from the Upper Paraguay Basin. The loci were highly polymorphic (mean = 7.28). According to all analysis, the two samples of P. reticulatum revealed pronounced genetic differentiation. F(st) value was 0.2290, R(st) value 0.1067 and AMOVA 22.90% (F(st) ) and 10.67% (R(st) ), all being highly significant (p < 0.001). The division of the fishes into two groups was confirmed by microsatellite multi-locus Bayesian assignment testing. The results obtained present evidence of genetic structuring in a P. reticulatum population.     

Forest Fire Impacts on Carbon Uptake, Storage, and Emission: The Role of Burn Severity in the Eastern Cascades, Oregon

This study quantifies the short-term effects of low-, moderate-, and high-severity fire on carbon pools and fluxes in the Eastern Cascades of Oregon. We surveyed 64 forest stands across four fires that burned 41,000 ha (35%) of the Metolius Watershed in 2002 and 2003, stratifying the landscape by burn severity (overstory tree mortality), forest type (ponderosa pine [PP] and mixed-conifer [MC]), and prefire biomass. Stand-scale C combustion ranged from 13 to 35% of prefire aboveground C pools (area ? weighted mean = 22%). Across the sampled landscape, total estimated pyrogenic C emissions were equivalent to 2.5% of statewide anthropogenic CO₂ emissions from fossil fuel combustion and industrial processes for the same 2-year period. From low- to moderate- to high-severity ponderosa pine stands, average tree basal area mortality was 14, 49, and 100%, with parallel patterns in mixed-conifer stands (29, 58, 96%). Despite this decline in live aboveground C, total net primary productivity (NPP) was only 40% lower in high- versus low-severity stands, suggesting strong compensatory effects of non-tree vegetation on C uptake. Dead wood respiratory losses were small relative to total NPP (range: 10–35%), reflecting decomposition lags in this seasonally arid system. Although soil C, soil respiration, and fine root NPP were conserved across severity classes, net ecosystem production (NEP) declined with increasing severity, driven by trends in aboveground NPP. The high variability of C responses across this study underscores the need to account for landscape patterns of burn severity, particularly in regions such as the Pacific Northwest, where non-stand-replacement fire represents a large proportion of annual burned area.     

Recombination and microdiversity in coastal marine cyanophages

Genetic exchange is an important process in bacteriophage evolution. Here, we examine the role of homologous recombination in the divergence of closely related cyanophage isolates from natural marine populations. Four core-viral genes (coliphage T4 homologues g20 , g23 , g43 and a putative tail fibre gene) and four viral-encoded bacterial-derived genes ( psbA , psbD , cobS and phoH ) were analysed for 60 cyanophage isolates belonging to five Rhode Island Myovirus (RIM) strains. Phylogenetic analysis of the 60 concatenated sequences revealed well-resolved sequence clusters corresponding to the RIM strain designations. Viral isolates within a strain shared an average nucleotide identity of 99.3–99.8%. Nevertheless, extensive microdiversity was observed within each cyanophage strain; only three of the 60 isolates shared the same nucleotide haplotype. Microdiversity was generated by point mutations, homologous recombination within a strain, and intragenic recombination between RIM strains. Intragenic recombination events between distinct RIM strains were detected most often in host-derived photosystem II psbA and psbD genes, but were also identified in some major capsid protein g23 genes. Within a strain, more variability was observed at the psbA locus than at any of the other seven loci. Although most of the microdiversity within a strain was neutral, some amino acid substitutions were identified, and thus microdiversity within strains has the potential to influence the population dynamics of viral–host interactions.