Effect of environmental fluctuations on invasion fronts

We determine the density profile and velocity of invasion fronts in one-dimensional infinite habitats in the presence of environmental fluctuations. The population dynamics is reformulated in terms of a stochastic reaction-diffusion equation and is reduced to a deterministic equation that incorporates the systematic contributions of the noise. We obtain analytical expressions for the front profile and velocity by constructing a variational principle. The effect of the noise differs, depending on whether it affects the density-independent growth rate, the intraspecific competition term or the Allee threshold. Fluctuations in the density-independent growth rate increase the invasion velocity and the population density of the invaded area. Fluctuations in the competition term also change the population density of the invaded area, but modify the invasion velocity only for certain initial conditions. Fluctuations in the Allee threshold can induce pulled or pushed invasion fronts as well as invasion failure. We compare our analytical results with numerical solutions of the stochastic partial differential equations and show that our procedure proves useful in dealing with reaction-diffusion equations with multiplicative noise.     

Home range and habitat use of male Reeves's Pheasant(Symaticus reevesii)during winter in Dongzhai National Nature Reserve,Henan Province,China

Home range and habitat use of male Reeves's Pheasant(syrmaticus reevesii)were studied during winter of 2001～2002 and 2002～2003 in the Dongzhai National Nature Reserve,Henan Province.Results from five individuals of Reeves's Pheasant with over 30 relocations,indicated that the average size of home range was 10.03±1.17 hm2 by Minimum Convex Polygon method.8.60±0.35 hm2 by 90% Harmonic Mean Transformation method,and 9.50±1.90 hm2 by 95% Fixed Kernel method.It was observed that the winter range is smaller than that in the breeding season.The mean core area of the home range was found to be 1.88±0.37 hm2.Although the habitat composition of the core area varied greatly for individuals,a large part of the habitats used were composed of conifer and broadleaf mixed forests,masson pine forests,fir forests,and shrubs.Habitat use within the study area was non-random,while habitats within home ranges were randomly used.Habitat use was dictated by tree diameter at breast height,shrub height and coverage at 2.0 m.The proximity between forests and shrubs were also found to be important in providing refuge for the birds during winter.Recommendations for conservation management include protecting the existing habitats in Dongzhai National Nature Reserve,increasing suitable habitat for Reeves's Pheasant through artificial plantations(e.g.firs),and restoring some parts of the large shrub area into forests.     

Caffeic acid derivatives: in vitro and in vivo anti-inflammatory properties

Caffeic acid and some of its derivatives such as caffeic acid phenetyl ester (CAPE) and octyl caffeate are potent antioxidants which present important anti-inflammatory actions. The present study assessed the in vitro and in vivo effects of five caffeic acid derivatives (caffeic acid methyl, ethyl, butyl, octyl and benzyl esters) and compared their actions to those of CAPE. In the model of LPS-induced nitric oxide (NO) production in RAW 264.7 macrophages, the pre-incubation of all derivatives inhibited nitrite accumulation on the supernatant of stimulated cells, with mean IC₅₀ (μM) values of 21.0, 12.0, 8.4, 2.4, 10.7 and 4.80 for methyl, ethyl, butyl, octyl, benzyl and CAPE, respectively. The effects of caffeic acid derivatives seem to be related to the scavenging of NO, as the compounds prevented SNAP-derived nitrite accumulation and decreased iNOS expression. In addition, butyl, octyl and CAPE derivatives significantly inhibited LPS-induced iNOS expression in RAW 264.7 macrophages. Extending the in vitro results, we showed that the pre-treatment of mice with butyl, octyl and CAPE derivatives inhibited carrageenan-induced paw edema and prevented the increase in IL-1β levels in the mouse paw by 30, 24 and 36%, respectively. Butyl, octyl and CAPE derivatives also prevented carrageenan-induced neutrophil influx in the mouse paw by 28, 49 and 31%, respectively. Present results confirm and extend literature data, showing that caffeic acid derivatives exert in vitro and in vivo anti-inflammatory actions, being their actions mediated, at least in part by the scavenging of NO and their ability to modulate iNOS expression and probably that of other inflammatory mediators.     

Solution structure of the first intracellular loop of prostacyclin receptor and implication of its interaction with the C-terminal segment of G alpha s protein

The amino acids (residues 39-51) responsible for the interaction between the first intracellular loop (iLP1) of the human prostacyclin receptor (IP) and G alpha s protein have been identified [Zhang, L., Huang, G., Wu, J., and Ruan, K. H. (2005) Biochemistry 44, 11389-11401]. To further characterize the structural/functional relationship of the iLP1 in coupling with the G alpha s protein, the solution structures of a constrained peptide (IP iLP1) that mimicked the iLP1 of the IP receptor in the absence and presence of a synthetic peptide, corresponding to the C-terminal 11 residues (Q384-L394 in the protein sequence) of the G alpha s protein (G alpha s-Ct), were determined by 2D 1H NMR spectroscopy. The NMR solution structural model of the iLP1 domain showed two turn structures in residues Arg41-Ala44 and Arg45-Phe49 with the conserved Arg45 at the center. The conformational change of the side chain of the Arg45 was observed upon the addition of the G alpha s-Ct peptide. On the other hand, the solution structural models of the G alpha s-Ct peptide in the absence and presence of the IP iLP1 peptide were also determined. The N-terminal domain (Q384-Q390 in the G alpha s protein) of the peptide adopted an alpha-helical conformation. However, the helical structure of the C-terminal domain (Q390-E392 in the G alpha s protein) of the peptide was destabilized upon addition of the IP iLP1 peptide. These structural studies have implied that there are direct or indirect contacts between the IP iLP1 domain and the C-terminal residues of the G alpha s protein in the receptor/G protein coupling. The possible charge and hydrophobic interactions between the two peptides were also discussed. These data prompted intriguing speculations on the IP/G alpha s coupling which mediates vasodilatation and inhibition of platelet aggregation.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

Natural and within-farmland biodiversity enhances crop productivity

Ongoing expansion of large-scale agriculture critically threatens natural habitats and the pollination services they offer. Creating patches with high plant diversity within farmland is commonly suggested as a measure to benefit pollinators. However, farmers rarely adopt such practice, instead removing naturally occurring plants (weeds). By combining pollinator exclusion experiments with analysis of honeybee behaviour and flower-visitation webs, we found that the presence of weeds allowed pollinators to persist within sunflower fields, maximizing the benefits of the remaining patches of natural habitat to productivity of this large-scale crop. Weed diversity increased flower visitor diversity, hence ameliorating the measured negative effects of isolation from natural habitat. Although honeybees were the most abundant visitors, diversity of flower visitors enhanced honeybee movement, being the main factor influencing productivity. Conservation of natural patches combined with promoting flowering plants within crops can maximize productivity and, therefore, reduce the need for cropland expansion, contributing towards sustainable agriculture.     

The genomic ancestry of individuals from different geographical regions of Brazil is more uniform than expected

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a "total ancestry" estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries--a phenomenon described and intended as the "whitening of Brazil"--is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations.