Morphometric analysis of Triatoma dimidiata populations (Reduviidae:Triatominae) from Mexico and Northern Guatemala

Triatoma dimidiata is one of the major vectors of Chagas disease in Latin America. Its range includes Mexico, all countries of Central America, Colombia, and Ecuador. In light of recent genetic analysis suggesting that the possible origin of this species is the Yucatan peninsula, we have analyzed populations from the state of Yucatan, San Luis Potosi, and Veracruz in Mexico, and a population from the southern region of the Yucatan peninsula located in Northern Guatemala, the region of El Peten. Classical morphometry including principal component, discriminant, sexual dimorphism, and wing asymmetry was analyzed. San Luis Potosi and Veracruz populations were indistinguishable while clearly separate from Yucatan and Peten populations. Despite important genetic differences, Yucatan and Peten populations were highly similar. Yucatan specimens were the smallest in size, while females were larger than males in all populations. Only head characters were necessary to distinguish population level differences, although wing fluctuating asymmetry was present in all populations. These results are discussed in light of recent findings suggesting genetic polymorphism in most populations of Triatoma dimidiata south of Chiapas to Ecuador.

Informing healthier choices: Information and intelligence for healthy populations

One of the commitments given in the Choosing Health white paper was to develop and implement a comprehensive public health information and intelligence strategy. This work was led by a specially constituted Task Force and informed by extensive public and professional consultation conducted in 2006. The resulting strategy sets out an approach that will strengthen health information and intelligence resources across England.This document reports on the results of consultation on the strategy.

Mechanisms of leukocyte lipid body formation and function in inflammation

An area of increasingly interest for the understanding of cell signaling are the spatio-temporal aspects of the different enzymes involved in lipid mediator generation (eicosanoid-forming enzymes, phospholipases and their regulatory kinases and phosphatases) and pools of lipid precursors. The compartmentalization of signaling components within discrete and dynamic sites in the cell is critical for specificity and efficiency of enzymatic reactions of phosphorilation, enzyme activation and function. We hypothesized that lipid bodies - inducible non-membrane bound cytoplasmic lipid domains - function as specialized intracellular sites of compartmentalization of signaling with major roles in lipid mediator formation within leukocytes engaged in inflammatory process. Over the past years substantial progresses have been made demonstrating that all enzymes involved in eicosanoid synthesis localize at lipid bodies and lipid bodies are distinct sites for eicosanoid generation. Here we will review our current knowledge on the mechanisms of formation and functions of lipid bodies pertinent to inflammation.

Selective suppression of leukocyte recruitment in allergic inflammation

Allergic diseases result in a considerable socioeconomic burden. The incidence of allergic diseases, notably allergic asthma, has risen to high levels for reasons that are not entirely understood. With an increasing knowledge of underlying mechanisms, there is now more potential to target the inflammatory process rather than the overt symptoms. This focuses attention on the role of leukocytes especially Th2 lymphocytes that regulate allergic inflammation and effector cells where eosinophils have received much attention. Eosinophils are thought to be important based on the high numbers that are recruited to sites of allergic inflammation and the potential of these cells to effect both tissue injury and remodelling. It is hoped that future therapy will be directed towards specific leukocyte types, without overtly compromising essential host defence responses. One obvious target is leukocyte recruitment. This necessitates a detailed understanding of underlying mechanisms, particularly those involving soluble che-moattractants signals and cell-cell adhesion molecules.

Identification of sex pheromones of Lutzomyia longipalpis (Lutz & Neiva, 1912) populations from the state of São Paulo, Brazil

In Brazil, four populations of Lutzomyia longipalpis each producing different sex pheromones are recognised. It has been suggested that these chemotype populations represent true sibling species. In this study we present the results of an analysis, by coupled gas cromotography - mass spectrometry, of the pheromones of males L. longipalpis from two different municipalities of the state of São Paulo. Our study showed that L. longipalpis from these two municipalities produced different sex pheromones from each other. This coupled with the remarkable difference between the epidemiological situation in Araçatuba and Espírito Santo do Pinhal, suggests that the (S)-9-methylgermacrene-B and cembrene-1 populations may have different vectorial capacities.

Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5% of F2 progeny were susceptible to S. mansoni infection.

The spread of incompatibility-inducing parasites in sub-divided host populations.

BACKGROUND:Maternally transmitted symbionts have evolved a variety of ways to promote their spread through host populations. One strategy is to hamper the reproduction of uninfected females by a mechanism called cytoplasmic incompatibility (CI). CI occurs in crosses between infected males and uninfected females and leads to partial to near-complete infertility. CI-infections are under positive frequency-dependent selection and require genetic drift to overcome the range of low frequencies where they are counter-selected. Given the importance of drift, population sub-division would be expected to facilitate the spread of CI. Nevertheless, a previous model concluded that variance in infection between competing groups of breeding individuals impedes the spread of CI.RESULTS:In this paper we derive a model on the spread of CI-infections in populations composed of demes linked by restricted migration. Our model shows that population sub-division facilitates the invasion of CI. While host philopatry (low migration) favours the spread of infection, deme size has a non-monotonous effect, with CI-invasion being most likely at intermediate deme size. Individual-based simulations confirm these predictions and show that high levels of local drift speed up invasion but prevent high levels of prevalence across the entire population. Additional simulations with sex-specific migration rates further show that low migration rates of both sexes are required to facilitate the spread of CI.CONCLUSION:Our analyses show that population structure facilitates the invasion of CI-infections. Since some level of sub-division is likely to occur in most natural populations, our results help to explain the high incidence of CI-infections across species of arthropods. Furthermore, our work has important implications for the use of CI-systems in order to genetically modify natural populations of disease vectors.

Correlated evolution of mating strategy and inbreeding depression within and among populations of the hermaphroditic snail Physa acuta

Inbreeding depression is one of the main forces opposing the evolution of self-fertilization. Of central importance is the hypothesis that inbreeding depression and selfing coevolve antagonistically, generating either low selfing rate and high inbreeding depression or vice versa. However, there is limited evidence for this coevolution within species. We investigated this topic in the hermaphroditic snail Physa acuta. In this species, isolated individuals delay the onset of egg laying compared to individuals having access to mates. Longer delays (''waiting times'') indicate more intense selfing avoidance. We measured inbreeding depression and waiting time in a large quantitative-genetic experiment (281 outbred families derived from 26 natural populations). We observed large genetic variance for both traits and a strong positive genetic covariance between them, most of which resided within rather than among populations. It means that, within populations, individuals with higher mutation load avoided selfing more strongly on average. This genetic covariance may result from pleiotropy and/or linkage disequilibrium. Whatever its genetic architecture, the fact it emerges specifically when individuals are deprived of mates suggests it is not fortuitous and rather reflects the action of natural selection. We conclude that a diversity of mating strategies can arise within populations subjected to variation in inbreeding depression.

Naturally acquired antibodies to merozoite surface protein (MSP)-1(19) and cumulative exposure to Plasmodium falciparum and Plasmodium vivax in remote populations of the Amazon Basin of Brazil

To infer recent patterns of malaria transmission, we measured naturally acquired IgG antibodies to the conserved 19-kDa C-terminal region of the merozoite surface protein (MSP)-1 of both Plasmodium vivax (PvMSP-1(19)) and Plasmodium falciparum (PfMSP-1(19)) in remote malaria-exposed populations of the Amazon Basin. Community-based cross-sectional surveys were carried out between 2002 and 2003 in subjects of all age groups living along the margins of the Unini and Jaú rivers, Northwestern Brazil. We found high prevalence rates of IgG antibodies to PvMSP-1(19) (64.0 - 69.6%) and PfMSP-1(19) (51.6 - 52.0%), with significant differences in the proportion of subjects with antibodies to PvMSP-1(19) according to age, place of residence and habitual involvement in high-risk activities, defining some groups of highly exposed people who might be preferential targets of malaria control measures. In contrast, no risk factor other than age was significantly associated with seropositivity to PfMSP-1(19). Only 14.1% and 19.3% of the subjects tested for antibodies to PvMSP-1(19) and PfMSP-1(19) in consecutive surveys (142 - 203 days apart) seroconverted or had a three fold or higher increase in the levels of antibodies to these antigens. We discuss the extent to which serological data correlated with the classical malariometric indices and morbidity indicators measured in the studied population at the time of the seroprevalence surveys and highlight some limitations of serological data for epidemiological inference.

Southern Cone Initiative for the elimination of domestic populations of Triatoma infestans and the interruption of transfusion Chagas disease: historical aspects, present situation, and perspectives

Created in 1991 by the governments of Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay, the Southern Cone Initiative (SCI) has been extremely important for Chagas disease control in this region. Its basic objective was to reach the interruption of this disease, chiefly by means of the elimination of the principal vector Triatoma infestans and by the selection of safe donors in the regional blood banks. After a summarized historic of SCI, the text shows the advance of technical and operative activities, emphasizing some factors for the initiative success, as well as some difficulties and constraints. The future of SCI will depend of the continuity of the actions and of political priority. Scientific community has been highly responsible for this initiative and its maintenance. At the side of this, national and international efforts must be involved and reinforced to assure the accomplishment of the final targets of SCI. Very specially, the Pan American Health Organization has cooperated with the Initiative in all its moments and activities,being the most important catalytic and technical factor for SCI success.

Endoglycan mediates malignant leukocyte rolling on e-selectin and signals through SYK and the MAPK pathway

Selectins play a key role regulating leukocyte migration into tissues by mediating leukocyte tethering (capture) and rolling on inflamed endothelium and/or on adherent leukocytes or platelets. During leukocyte rolling, endothelial E- or P-selectin bind to glycoprotein ligands carrying sialyl Lewis χ (sLex) determinant. P-selectin glycoprotein ligand-1 (PSGL-1) is a common ligand for L-, P- and E-selectin, which sequentially cooperates with CD44 and E- selectin ligand-1 (ESL-1) to roll on E-selectin. During rolling on endothelial selectins, PSGL-1 and CD44 signal through Src family kinases and Syk, leading to αι_β2 integrin partial activation and slow rolling on intercellular adhesion molecule-1 (ICAM-1). Leukocyte exposure to chemokines then leads to firm adhesion. Little information is available on ligands that mediate malignant leukocyte rolling on E- selectin. We defined these ligands on U937 monoblasts by immunoadsorbtion and immunoblotting using mAb raised against CD43, CD44, PSGL-1, sLex/CLA determinants and E-selectin/IgM chimera. Immunoblotting and blot rolling assays demonstrated that PSGL-1, CD43, CD44 and a -125 kDa sLex/CLA positive ligand contribute to support E-seiectin- dependent rolling. This -125 kDa ligand is endoglycan, a member of the CD34 family of sialomucins. Endoglycan was frequently detected by flow cytometry on primary leukemia, lymphoma and multiple myeloma ceils (in -50% of cases). Endoglycan, immunopurified from U937 cells, as well as endoglycan/IgG chimera efficiently supported E-selectin dependent rolling. Membrane fractionation on sucrose gradient demonstrated that endoglycan is expressed in lipid rafts. We tested the hypothesis that it signals, like PSGL-1 and CD44, through Src kinases and the MAPK pathway. Indeed, endoglycan engagement induced Syk and ERK phosphorylation in a iipid raft-dependent manner. Syk activation was dependent on Src kinase activity. Downstream of Syk, endoglycan activated PI3K and Akt as well as Bruton's tyrosine kinase and p38 MAPK. Thus, endoglycan is a ligand for endothelial selectins which may contribute to regulate leukemia, lymphoma and multiple myeloma cell trafficking and interactions with bone marrow microenvironment. - Les sélectines contrôlent la migration tissulaire des leucocytes en assurant leur capture et leur roulement sur l'endothélium vasculaire enflammé et/ou sur des plaquettes ou des leucocytes adhérant à la paroi vasculaire. Lors du roulement leucocytaire, les sélectines endothéliales (E- et P-sélectine) se lient à des ligands porteurs du saccharide sialyl Lewis χ (sLex). PSGL-1 est un ligand commun des sélectines qui coopère avec CD44 et ESL-1 pour permettre la capture et le roulement des neutrophiles. Lorsque PSGL-1 et CD44 se lient aux sélectines endothéliales, elles induisent la phosphorylation des kinases Src et de Syk conduisant à l'activation partielle de l'intégrine aLp2 et au ralentissement des leucocytes sur les sélectines et ICAM-1. Les chimiokines induisent ensuite l'adhésion ferme des leucocytes. Les ligands des sélectines qui assurent le roulement, sur la E-sélectine, des cellules issues d'hémopathies malignes sont peu connus. Nous avons caractérisé ces ligands en les purifiant avec des anticorps dirigés contre CD43, CD44, PSGL-1, sLex/CLA et en utilisant la chimère E-sélectine/IgM. Des tests d'adhésion ont montré que PSGL-1, CD43, CD44 et une glycoprotéine de ~125 kDa soutiennent les interactions cellulaires dépendant de la E- sélectine. Le ligand de -125 kDa a été identifié comme étant l'endoglycan. Il a été détecté, par cytométrie de flux, sur les cellules leucémiques, les cellules de lymphomes ou de myélome multiple, dans ~50% des cas analysés. Sa forme membranaire, immunopurifiée, ou recombinante (endoglycan/lgG) soutient les interactions cellulaires dépendant de la E- sélectine. Nous avons montré qu'il réside dans les rafts lipidiques membranaires puis avons testé l'hypothèse que l'endoglycan, comme PSGL-1 et CD44, induit une signalisation via les kinases de type Src et la voie des MAPK. Nous avons pu observer que son engagement induit la phosphorylation de Syk et de ERK pour autant que la structure des rafts soit préservée. En aval de Syk, l'endoglycan active la PI3K, Akt, Btk et la MAPK p38. Ces résultats montrent que l'endoglycan est un ligand des sélectines endothéliales qui pourrait participer au contrôle du trafic et des interactions des cellules leucémiques, de lymphomes ou de myélomes multiples avec leur microenvironnement. - Le sang est un élément clé du fonctionnement de notre corps. La circulation sanguine permet la communication et le transfert de molécules et cellules entre divers organes. Lors d'une inflammation aiguë due à une réaction allergique, une infection ou une blessure, on observe un oedème local accompagné de rougeur, de chaleur et souvent de douleurs. Au sein des tissus enflammés, on observe des globules blancs (leucocytes) et diverses molécules inflammatoires qui attirent les leucocytes dans les tissus lésés (chimiokines). Le sang est composé de globules rouges, de plaquettes et de leucocytes spécialisés dans les défenses immunes. Pour atteindre le site d'inflammation, les leucocytes doivent quitter la circulation sanguine. Ils utilisent pour cela des molécules d'adhésion présentes à leur surface qui se lient à d'autres molécules d'adhésion de la paroi sanguine. Leurs interactions permettent aux leucocytes de rouler à la surface du vaisseau sanguin. Lorsqu'ils roulent au voisinage d'un site d'inflammation, les leucocytes sont exposés à des chimiokines qui induisent leur arrêt et les dirigent dans les tissus enflammés. Ce processus physiologique est aussi impliqué dans des pathologies telles que l'infarctus, l'artériosclérose ou la thrombose. Il peut être détourné à des fins moins louables par des cellules cancéreuses pour permettre leur dissémination (métastatisation). Dans ce travail de thèse, nous avons caractérisé une molécule d'adhésion qui soutient l'adhésion des leucocytes aux sélectines endothéliales: l'endoglycan. Nous avons observé que cette molécule d'adhésion est fréquemment exprimée par les cellules malignes de nombreuses maladies du sang comme les leucémies, les lymphomes et le myélome multiple. Nous avons également pu montrer que l'endoglycan envoie des signaux à l'intérieur des cellules malignes lorsqu'elles se lient aux sélectines endothéliales. Ces signaux pourraient jouer un rôle déterminant dans la régulation des interactions des cellules malignes avec leur microenvironnement. Elles pourraient peut-être aussi favoriser leur survie et leur prolifération.

Morphological analysis of three populations of Anopheles (Nyssorhynchus) nuneztovari Gabaldón (Diptera: Culicidae) from Colombia

Based on the results of comparative analyses of 1,039 specimens of several progenies of Anopheles nuneztovarifrom three localities in Colombia, eight costal wing spot patterns were observed. Patterns I and III were the most frequent: 77.96% and 11.36%, respectively. Using the diagnostic characters ratio of the length of the basal dark area of hind tarsomere II/length of hind tarsomere II, ratio of the length of the humeral pale spot/length of the pre-humeral dark spot, and the ratio of the length of the subcostal pale spot/length of the distal sector dark spot (DS-III2/Ta-III2, HP/PHD, SCP/DSD) approximately 5% of the adult females were misidentified as a species of Nyssorhynchus, different from An. nuneztovari. Approximately 5% of the specimens showed DS-III2/Ta-III2 ratio less than 0.25 (range 0.21 - 0.24), and among them 3.34% shared a HP/PHD ratio less than 1.50. Consequently, 1.52% of An. nuneztovari individuals can be misidentified as Anopheles oswaldoi. In those specimens with the DS-III2/Ta-III2 ratios higher than 0.25, 34.45% displayed SCP/DSD values greater than 0.50 and of these, 3.65% displayed HP/PHD values greater than 1.8. This combination of characters could lead one to misidentify samples of An. nuneztovari as Anopheles rangeli. Similarly, 2.43% of the females could be identified erroneously as either Anopheles aquasalis or Anopheles benarrochi. Individuals with a HP/PHD ratio greater than 2.0, could be misidentified as Anopheles trinkae, Anopheles strodei or Anopheles evansae. A distinct combination of diagnostic characters for An. nuneztovari from Colombia is proposed.

Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae)

Lutzomyia longipalpis s.l., the main vector of Leishmania chagasi in Latin America, is a species complex although the exact number of siblings is yet unknown. In Brazil, the siblings differ in male copulatory courtship songs and pheromones that most certainly act as pre-zygotic reproductive barriers. Here we analysed the reproductive isolation between three allopatric and two sympatric populations of Lu. longipalpis s.l. from Brazil. The results indicate a strong copulatory and pre-mating isolation between the three allopatric populations. In addition, the results also indicate a stronger pre-mating isolation between the two sympatric siblings than between the three allopatric ones, suggesting a role for reinforcement in the speciation of the Lu. longipalpis s.l. complex.