Characterization of the intestinal microbiota of natural populations of Lutzomyia evansi: vector of visceral Leishmaniasis

Lutzomyia evansi (Diptera: Psychodidae) is a phlebotomine “sandfly” insect endemic to the Caribbean coast of Colombia with epidemiological significance for being the main vector of leishmaniasis disease, which is caused by Leishmania spp parasites. Sand flies (164 species in Colombia) in general are able to transmit other parasites as Bartonella spp, and virus mostly from vesiculovirus group, affecting human and animal health. This group of insects has been studied in Colombia in relation to vectorial role, geographical distribution and epidemiological importance, but vaccine absence for the most important disease they transmit (leishmaniasis) encourage the implementation of vector control measures as key factor for the disease control. In this sense entomological surveillance and prevention measures have been implemented but most of the time in transmission episodes is frequently invested in taxonomical work. In spite of the importance of phlebotomine sand flies and the necessity of their control, very few studies exist in Colombia and in general in America, related to their biology, ecology or many other basic aspects, which are relevant for their diminishing or control. Biological control of insect vectors or the parasites or pathogens they transmit is a topic of research actually addressed by academic and scientific points of view and encouraged by health authorities given difficulties as insecticide resistance and costs for traditional methods. For Lutzomyia spp., sand flies, this is one basic study providing, basic information about microbial communities (bacteria) associated to their biological stages (larvae, pupa and adult) and evaluating as basic line of evidence, potential effects of some of them on Lesihmania. Although Lu evansi and in general sandflies can harbor pathogenic and non-pathogenic microorganisms in their guts, there is little knowledge related to the intestine ecology and to the bacterial diversity present in the gut of wild populations. Presence of some bacteria including Wolbachia spp is of significance and may encourage further investigation on the possible effects of those bacteria in Leishmania transmission given the proven effect on some viruses and other parasites in their vectors. In this study, conventional microbiological methods and molecular ones, were used to explore the composition of bacterial communities associated with the gut of immature and adult stages of wild populations of Lu. evansi from the department of Sucre (Caribbean coast of Colombia). Different lines of evidence were addressed for identification of the bacteria including ribosomal intergenic spacer analysis (RISA) and 16S rRNA and gyrB gene sequences variation. The genetic profile of bacterial populations was generated and compared by temperature gradient gel electrophoresis (TTGE) from total DNA of Lutzomyia gut. Concomitant Wolbachia and Leishmania infection in Lu. evansi and other species was also evaluated by PCR. Leishmanicidal and antimicrobial activity of Pantoea ananatis, Ochrobactrum anthropi and Enterobacter cloacae, isolated from the gut of Lu. evansi, were evaluated as well as the sensitivity of these bacteria to commonly used antibiotics. The culture-dependent techniques indicated intestinal bacteria belonging to Acinetobacter, Enterobacter, Pseudomonas, Ochrobactrum, Shinella and Paenibacillus being the dominant bacteria larvae. Lysobacter, Microbacterium, Streptomyces, Bacillus and Rummeliibacillus were found in pupae; Staphylococcus, Streptomyces, Brevibacterium, Acinetobacter, Enterobacter and Pantoea were isolated from adults. Fingerprint pattern of PCR - TTGE had statistical significant variations in bacterial communities in Lu. evansi when immature and adult stages were compared, as also when engorged condition and origin of insects were considered. Results indicated 20% of infection by Wolbachia in all samples of Lutzomyia evaluated. This endosymbiotic bacteria was found in three species: Lutzomyia cayennensis and Lutzomyia dubitans with 3 positive pools= 8.5% for both species, and Lutzomyia evansi, with a positive pool= 2.8%. Two Wolbachia genotypes (strains) were clearly found, wLev in Lu dubitans, Lu cayennensis, and Lu evansi; while wLcay was found only in Lu cayennensis. Evidence of Wolbachia infections in natural Lutzomyia populations encourage further investigation on the possible effects of this bacteria in Leishmania transmission given the proven efficacy in biological control of some parasites transmitted by vectors. The highest percentage of inhibition against Leishmania procyclic promastigotes was observed with bacterial concentrations of 108 CFU/ml of E. cloacae (77.29 ± 0.6%) and P. ananatis (70.17% ± 1.1). The inhibitory growth activity of procyclic L. infantum promastigotes shown by extracts of E. cloacae and P. ananantis suggests that the presence of these bacteria in the vector intestine could be affecting the parasite development to metacyclic stages infective to human hosts, which will be desirable to corroborate. O. anthropi was the isolate with the highest number of antibiotic resistance patterns while P. ananatis and E. cloacae showed greater sensitivity to the antibiotics evaluated.Doctorad

EMU and Trade : A PPML re-assessment with intra-national trade flows

Since Rose's (2000) path-breaking study, a lot of studies have been carried out on the effect of currency unions on trade. Both Rose's striking finding that sharing a currency union more than triples trade between countries and the creation of the euro have propelled an intense debate on this issue and, in particular, about the effect of the Economic and Monetary Union (EMU) on trade. More than 50 papers have examined the effect of EMU on bilateral trade flows given that it is, by far, the most important monetary union. However, so far the results vary greatly across studies and even the most recent articles provide mixed results. Whereas Glick and Rose (2016) and Larch, Wanner, and Yotov (2018) find a positive EMU effect on trade, Mika and Zymek (2018) and Larch, Wanner, Yotov, and Zylkin (2019) provide no evidence of a positive effect on trade. Therefore, the debate is still ongoing

First record of the sand fly Warileya (Hertigia) hertigi from Antioquia, Colombia

Introduction: The genus Warileya is one of the least-known taxa of sandflies, comprising only nine species, i.e., W. (Warileya) phlebotomanica, W. (Hertigia) hertigi, W. (W.) rotundipennis, W. (W.) nigrosacculus, W. (W.) yungasi, W. (W.) fourgassiensis, W. (W.) lumbrerasi, W. (W.) euniceae and W. (W.) leponti. Objective: To document the presence of a species of the genus Warileya in Antioquia, Colombia. Materials and methods: Sandflies were collected in a cavern of the Cañón del Río Claro Natural Reserve, of the municipality of San Francisco, Antioquia department, Colombia. Phlebotomine sampling was carried out using a CDC light trap during three consecutive nights in May of 2008. Taxonomical determination was based on a revision of the type material of the species and through the use of standard keys for American sandflies. Results: Five male and two female sandflies were taxonomically identified as W. (H.) hertigi. In both sexes, the absence of setal scars in the anepisternum, proepimeron and clypeus; the presence of two transverse rows of setal scars in the tergites; and the short length of the vena gamma were notable. Conclusion: The finding of W. (H.) hertigi increases the number of sandfly species found in Antioquia department to 64. In total, 164 sandfly species have been recorded in Colombia

Análisis de la estructura primaria y secundaria del ARN de transferencia mitocondrial para serina en siete especies de Lutzomyia

Introduction. Lutzomyia sand flies are involved in the transmission of the parasite Leishmania spp. in America. The taxonomy of these vectors is traditionally based on morphological features of the adult stage, particularly the paired structures of the head and genitalia. Although these characters are useful to distinguish most species of Lutzomyia, morphological identification may be complicated by the similarities within subgenera and species group.Objective. To evaluate the utility of mitochondrial serine transfer RNA tRNASer for taxonomic identification of Lutzomyia.Materials and methods. Seven sand fly species, each representing one of the 27 taxonomic subdivisions in genus Lutzomyia, were analyzed including L. trinidadensis (Oswaldoi group), L. (Psychodopygus) panamensis, L.(Micropygomyia) cayennensis cayennensis, L. dubitans (Migonei group), L. (Lutzomyia) gomezi, L. rangeliana (ungrouped) and L. evansi (Verrucarum group). The mitochondrial tRNASer gene, flanked by the cytochrome b and NAD dehydrogenase subunit one genes, was extracted, amplified and sequenced from each specimen. Secondary structure of the tRNASer was predicted by comparisons with previously described homologous structures from other dipteran species.Results. The tRNASer gene ranged in size from 66 base pairs in L. gomezi to 69 base pairs in L.trinidadensis. Fourteen polymorphic sites, including four insertion-deletion events, were observed in the aligned 70 nucleotide positions. The majority of the substitutions were located in the dihydrouridine, ribothymidine-pseudouridine-cytosine and variable loops, as well as in the basal extreme of the anticodon arm. Conclusion. Changes of primary sequence of the tRNASer provided useful molecular characters for taxonomic identification of the sand fly species under consideration.Introducción. Los insectos del género Lutzomyia son los responsables de la transmisión del parásito Leishmania spp. en América. La taxonomía de estos vectores se fundamenta en los caracteres morfológicos que exhiben los adultos, principalmente, en las estructuras pareadas de la cabeza y los genitales. Aunque estos caracteres permiten distinguir la mayoría de los taxones, la similitud en algunos subgéneros y grupos de especies pone límites a la identificación por criterios morfológicos.Objetivo. Evaluar la utilidad del ARN de transferencia mitocondrial para serina ARNtSer en la determinación taxonómica de Lutzomyia.Materiales y métodos. Se analizaron siete especies flebotomíneas, L. trinidadensis, L. panamensis, L. cayennensis cayennensis, L. dubitans, L. gomezi, L. rangeliana y L. evansi. A partir de cada individuo, se extrajo, amplificó y obtuvo la secuencia del gen mitocondrial que codifica para el ARNtSer, delimitado por los genes citocromo b y NAD deshidrogenasa uno. La estructura secundaria del ARNtSer se infirió teniendo como base las estructuras homólogas descritas en otros insectos del orden Diptera.Resultados. La longitud del gen ARNtSer osciló entre 66 pb en L. gomezi y 69 pb en L. trinidadensis. En el alineamiento nucleotídico de 70 posiciones, se detectaron 14 sitios polimórficos, incluyendo cuatro eventos indel. La mayoría de las sustituciones correspondieron a las lupas dihidrouridina, ribotimidina-pseudouridina-citosina y variable, así como al extremo basal del brazo anticodón.Conclusión. Los cambios en la secuencia primaria de nucleótidos y los rearreglos en la estructura secundaria del ARNtSer son potencialmente útiles para la discriminación taxonómica de las especies flebotomíneas estudiadas

Nuevos registros de flebotomíneos (Diptera: Psychodidae) en el área de influencia del río Amoyá en Chaparral, Tolima

Introduction. In Colombia, the diversity of phlebotomine sand flies is high, with 162 recorded species, and which include vectors of Leishmania spp.Objective. To identify the sand fly species of medically importance in the area of influence from Amoyá River Hydroelectric Project, Colombia.Materials and methods. Sand flies were collected with CDC light traps, Shannon traps and sticky traps, from 15 villages in Chaparral County, Tolima.Results. A total of 1,077 adult sand fly specimens were collected. Thirteen species were found in the genus Lutzomyia and one species in the genus Warileya. Among the Lutzomyia species, three species--Lutzomyia longiflocosa, Lutzomyia columbiana and Lutzomyia nuneztovari--are important for their epidemiological history. Lutzomyia suapiensis was a new record for Colombia, and Warileya rotundipennis was recorded for the first time in Tolima.Conclusions. This study contributed to an increased knowledge of Colombian sand flies in terms of (1) expanding the geographical distribution of members of the subfamily Phlebotominae, (2) gaining estimates of species-richness and species associations in central Colombia, and (3) providing a better understanding of epidemiology of leishmaniasis in the Chaparral area.Introducción. En Colombia, la diversidad de flebotomíneos es alta, con 162 especies registradas que incluyen especies vectoras de Leishmania spp.Objetivo. Identificar las especies de flebotomíneos de importancia médica dentro del área de influencia del Proyecto Hidroeléctrico del río Amoyá, Colombia.Materiales y métodos. Los flebotomíneos fueron recolectados con trampas de luz de tipo CDC, Shannon y adhesivas, en 15 veredas del municipio de Chaparral, departamento de Tolima.Resultados. Un total de 1.077 especímenes adultos de flebotomíneos fueron recolectados e identificados como pertenecientes a 13 especies del género Lutzomyia França, 1924 y una especie del género Warileya Hertig, 1948. Entre las especies del género Lutzomyia recolectadas, Lu. longiflocosa (Morales, Osorno y Muñoz, 1970), Lu. columbiana (Ristorcelli y Van Ty, 1941) y Lu. nuneztovari (Ortiz, 1954) son importantes por sus historiales epidemiológicos. Se resalta por primera vez la presencia de Lu. suapiensis (Le Pont, Torrez-Espejo y Dujardin, 1997) en Colombia y de Warileya rotundipennis (Fairchild y Herting, 1951) en el departamento de Tolima.Conclusión. Este estudio contribuye al conocimiento de la distribución geográfica de la subfamilia Phlebotominae en Colombia y favorece localmente a la comprensión de la riqueza y taxonomía de estos insectos, para un mejor entendimiento de la transmisión de la leishmaniasis en el municipio de Chaparral. doi: http://dx.doi.org/10.7705/biomedica.v32i2.438

Wikipedia como herramienta de aprendizaje en la docencia de derecho del trabajo y de la seguridad social

Memoria ID12-0223. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2012-2013

El euro y la integración comercial española: un análisis comparado

En este trabajo utilizamos un panel de datos de comercio durante el período 1988-2001 para estimar el impacto de la Unión Monetaria Europea (UME) en los flujos comerciales. Las ecuaciones de gravedad estimadas muestran que la UME ha llevado a un incremento del comercio bilateral entre el 10 y el 14 por ciento. El análisis por países revela que España ha sido el país que, junto con Irlanda, ha experimentado un mayor incremento de su comercio en los tres primeros años de vigencia del euro

FAUNA DE FLEBOTOMÍNEOS (DIPTERA: PSYCHODIDAE) EN ACANDÍ (CHOCÓ)

Se informa la presencia de 16 especies del género Lutzomyia França y dos especies del género Brumptomyia Sherlock para la costa del Darién-Caribe colombiano, resaltando el hallazgo de Lutzomyia atroclavata (Knab) y Brumptomyia mesai (Sherlock) como nuevos registros para el Departamento del Chocó. El estudio entomológico fue realizado usando trampas de luz CDC y búsqueda activa con aspiradores bucales en raíces tabulares, en la Reserva Natural llamada “El Aguacate”, Acandí. Se colectaron 1205 individuos, de los cuales sobresalen Lutzomyia panamensis, Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia sanguinaria, Lutzomyia olmeca bicolor y Lutzomyia hartmanni reconocidos como potenciales vectores de leishmaniasis cutánea en el nuevo mundo. Este estudio proporciona información nueva sobre la distribución geográfica de especies de flebotomíneos y contribuciones taxonómicas relevantes para la región Caribe del Chocó en Colombia

Trade effects of monetary agreements: Evidence for OECD countries

This paper analyses the effects of monetary agreements on trade flows using a sample of 25 OECD countries over the period 1950-2004. We find that these agreements have boosted intra-bloc trade. This result especially applies to the case of the euro. More importantly, in contrast to regional trade agreements, all monetary agreements analysed show evidence of trade-creating effects with third countries. Finally, only the euro shows a symmetric impact for the trade-creating effect with non-members, that is, using the euro promotes both the Eurozone's exports and its imports to non-Eurozone markets to a similar extent.

The impact of the euro on firm export behaviour: does firm size matter?

The goal of this paper is to assess the impact of the euro on the relationship between firm size and exports. We employ previous new-new trade theory models to derive some hypotheses that are tested using a representative sample of Spanish manufacturing firms. The results indicate that the introduction of the euro has remarkably weakened the role of firm size in the decision to export to the Eurozone. What is more, the change in the proportion of exports to the Eurozone is negatively related to firm size. Our results suggest that the euro has reduced the threshold size in order to export to Eurozone countries. Copyright 2011 Oxford University Press 2010 All rights reserved, Oxford University Press.