Publications by authors named "Andrés Gómez-Palacio"

24 Publications

  • Page 1 of 1

Bacteriome depiction and the trophic status of the largest Northern highland lake from Andes system: Lago de Tota, Boyacá, Colombia.

Arch Microbiol 2021 May 12. Epub 2021 May 12.

Escuela de Ciencias Biológicas, Laboratorio de Investigación en Genética Evolutiva - LIGE, L-214, Universidad Pedagógica Y Tecnológica de Colombia, Avenida Central del Norte 39-115, Tunja, Boyacá, Colombia.

Lago de Tota is the largest highland lake in Colombia and one of the most remarkable of Northern Andean Mountain range. This lake is under an anthropogenic-based eutrophication process as a consequence of non-sustainable agriculture practices developing nearby. Notable relationship between the trophic status and Bacteriome loop dynamics has been increasingly disclosed in lakes worldwide. We performed a 16S sequencing analysis to depict the bacterial community present and we inferred its potential gene function in Lago de Tota. Parameters for determining current trophic condition such as total nitrogen (TN), dissolved carbon (DOC), particulate organic matter (POM), and chlorophyll-a (chl-a) were measured. A total of 440 Operational Taxonomic Units (OTUs) arranged into 50 classes were identified based on V3-V4 regions of the 16S rRNA gene, harboring high-frequent likely found environmental classes such as Actinobacteria, Gammaproteobacteria, Bacteroidia, Acidimicrobia, and Verrucomicrobiae. A total of 26 bacterial classes configure most abundant predicted functional processes involved in organic matter decomposition (i.e., carbohydrate metabolism, amino acid metabolism, xenobiotic biodegradation, and energy metabolism). In general, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria show the highest potential gene functional contributors, although other low-frequent classes OTUs are also relevant in processes of carbohydrate metabolism, xenobiotic biodegradation, and energy metabolism. The Trophic State Index indicates an oligo-mesotrophic status, and additional variables measured (i.e., POM, DOC) suggest the increasing carbon accumulation. Results provide preliminary evidence for several bacteria groups related to eutrophication of Lago de Tota. Under this picture, we suggest that further studies for Bacteriome loop spatial-temporal description are essential to inform local water quality monitoring strategies.
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http://dx.doi.org/10.1007/s00203-021-02341-3DOI Listing
May 2021

Surveillance of Zika virus in field-caught Aedes aegypti and Aedes albopictus suggests important role of male mosquitoes in viral populations maintenance in Medellín, Colombia.

Infect Genet Evol 2020 11 21;85:104434. Epub 2020 Jun 21.

Laboratorio de Investigación en Genética Evolutiva, Universidad Pedagógica y Tecnológica de Colombia, Boyacá, Colombia.

Due to the rapid spread of Zika virus (ZIKV) infection after its emergence in the Americas in 2015 and its relationship with birth defects, it became declared a Public Health Emergency of International Concern (WHO). The main mechanism by which this virus circulates in nature is horizontal transmission between vectors and humans. However, it has been suggested that vertical transmission (parent to offspring infection) or venereal mosquito-mosquito transmission may have an important role in viral populations maintenance during inter-epidemic periods. In this study we evaluate the presence of ZIKV in males and females of Aedes aegypti and Ae. albopictus in Medellín, Colombia, throughout the post-epidemic period of 2017 and 2018. A total of 7986 mosquitoes Aedes sp. resting within houses were captured and grouped in 2768 pools; 146 of these were RT-PCR positive for ZIKV, of which 38 (26%) were male mosquito pools (36 of Ae. aegypti and 2 of Ae. albopictus). The partial NS5 gene was sequenced in all ZIKV PCR-positive pools to confirm the ZIKV presence throughout spatial and temporal sampling. The results suggest a vector role of ZIKV by Ae. Albopictus; and because it is well known that male mosquitoes are not hematophagous, the high rate detection of ZIKV in male Aedes mosquitoes pools supports the existence of vertical or venereal transmission in Medellín, which can contribute to ZIKV maintenance during low transmission periods. This study provides a better understanding of the population dynamics of ZIKV in an endemic region during an inter-epidemic period and supports alternative transmission pathways as a mechanism to maintain endemism of this arbovirus.
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http://dx.doi.org/10.1016/j.meegid.2020.104434DOI Listing
November 2020

DNA barcoding for identifying synanthropic flesh flies (Diptera, Sarcophagidae) of Colombia.

Acta Trop 2018 Jun 3;182:291-297. Epub 2018 Feb 3.

Grupo de Investigación en Ciencias Biomédicas - GICB, Universidad Pedagógica y Tecnológica de Colombia, Boyacá, Colombia.

The first step for a successful use of any insect as indicator in forensic sciences is providing a precise taxonomic identification at species level. Due to morphology-based identification of Sarcophaginae flies (Diptera, Sarcophagidae) is often difficult and requires strong taxonomic expertise, their use as forensic indicators has been limited. Consequently, molecular-based approaches have been accepted as alternative means of identification. Thus, we aimed testing the efficiency of the barcode region of the mitochondrial cytochrome oxidase subunit I (COI) gene for identification of synanthropic flesh flies of several species of the genera Peckia, Oxysarcodexia, Ravinia, and Tricharaea collected in Colombia. The 645-bp fragment of COI was amplified and aligned (215 parsimoniously informative variable sites). We calculated Kimura two-parameter genetic distances and reconstruct a Neighbor-Joining phylogenetic tree. Our Neighbor-Joining tree recovered all species as monophyletic, and confirmed a new species of the genus Ravinia as also indicated by the interspecific genetic divergences and morphological observations. We obtained a 100% of identification success. Thus, the COI barcodes showed efficiency as an alternative mean of identification of species of flesh flies collected on decaying organic matter in Colombia.
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http://dx.doi.org/10.1016/j.actatropica.2018.01.020DOI Listing
June 2018

Aedes albopictus (Skuse, 1894) infected with the American-Asian genotype of dengue type 2 virus in Medellín suggests its possible role as vector of dengue fever in Colombia.

Biomedica 2017 Mar 29;37(0):135-142. Epub 2017 Mar 29.

Grupo de Investigación en Ciencias Biomédicas, Escuela de Ciencias Biológicas, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia.

Introduction: Aedes aegypti and Ae. albopictus are recognized vectors of dengue, yellow fever, chikungunya and Zika arboviruses in several countries worldwide. In Colombia, Ae. albopictus geographical distribution has increased to include highly populated cities such as Cali and Medellín. Although this species has been frequently found in urban and semi-urban zones in the country, its role as vector of the dengue fever is poorly known.

Objective: To identify the presence of Ae. albopictus specimens naturally infected with dengue virus collected in Medellín.

Materials And Methods: Insects were collected in the Universidad Nacional de Colombia campus in Medellín. Individuals were classified as Ae. albopictus and confirmed by DNA barcode region analysis. Mosquitoes were processed for dengue virus identification, and a fragment of the NS3 gen was sequenced and compared with DENV-2 genotypes reported in the literature.

Results: Sequence analysis of COI indicated Ae. albopictus individuals were similar to those recently reported in Colombia, and genetically close to those from other regions worldwide. Among the pools tested one was positive for DENV-2, and the NS3 analysis indicated it belonged to the Asian-American clade.

Conclusion: We report the presence Ae. albopictus naturally infected with the Asian-American genotype of DENV-2 in Colombia. The presence of Ae. albopictus specimens carrying the most common genotype infecting humans in a highly populated city such as Medellín indicates its potential role as dengue vector in Colombia and highlights the relevance of including it in current vector surveillance strategies.
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http://dx.doi.org/10.7705/biomedica.v37i0.3474DOI Listing
March 2017

Infection Rates by Dengue Virus in Mosquitoes and the Influence of Temperature May Be Related to Different Endemicity Patterns in Three Colombian Cities.

Int J Environ Res Public Health 2016 07 21;13(5). Epub 2016 Jul 21.

Grupo de Biología y Control de Enfermedades Infecciosas, Universidad de Antioquia, Sede de Investigaciones Universitarias (SIU), Calle 62 # 52-59 Laboratory 620, P.O. Box: 1226, Medellín 050010, Colombia.

Colombia is an endemic country for dengue fever where the four serotypes of virus dengue (DENV1-4) circulate simultaneously, and all types are responsible for dengue cases in the country. The control strategies are guided by entomological surveillance. However, heterogeneity in aedic indices is not well correlated with the incidence of the disease in cities such as Riohacha, Bello and Villavicencio. As an alternative, molecular detection of dengue virus in mosquitoes has been proposed as a useful tool for epidemiological surveillance and identification of serotypes circulating in field. We conducted a spatiotemporal fieldwork in these cities to capture adult mosquitoes to assess vector infection and explain the differences between Breteau indices and disease incidence. DENV infection in females and DENV serotype identification were evaluated and infection rates (IR) were estimated. The relationship between density, dengue cases and vector index was also estimated with logistic regression modeling and Pearson's correlation coefficient. The lack of association between aedic indices and dengue incidence is in agreement with the weak associations between the density of the mosquitoes and their infection with DENV in the three cities. However, association was evident between the IR and dengue cases in Villavicencio. Furthermore, we found important negative associations between temperature and lag time from two to six weeks in Riohacha. We conclude that density of mosquitoes is not a good predictor of dengue cases. Instead, IR and temperature might explain better such heterogeneity.
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http://dx.doi.org/10.3390/ijerph13070734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962275PMC
July 2016

The nuclear elongation factor-1α gene: a promising marker for phylogenetic studies of Triatominae (Hemiptera: Reduviidae).

Infect Genet Evol 2016 09 4;43:274-80. Epub 2016 Jun 4.

Grupo de Biología y Control de Enfermedades Infecciosas - BCEI, Universidad de Antioquia (UdeA), Medellín, Antioquia, Colombia. Electronic address:

Molecular systematics is a remarkable approach for understanding the taxonomic traits and allows the exploration of the inter-population dynamics of several species in the Triatominae subfamily that are involved in Trypanosoma cruzi transmission. Compared to other relevant species that transmit vector-borne diseases, such as some species of the Diptera, there are relatively few nuclear genetic markers available for systematic studies in the Triatominae subfamily. Molecular systematic studies performed on Triatominae are based on mitochondrial gene fragments and, less frequently, on nuclear ribosomal genes or spacers. Due to the fact that these markers can occasionally present problems such as nuclear mitochondrial genes (NUMTs) or intra-genomic variation for high gene copy numbers, it is necessary to use additional nuclear markers to more reliably address the molecular evolution of Triatominae. In this study, we performed phylogenetic analysis using the nuclear elongation factor-1 alpha (EF-1α) gene in individuals from 12 species belonging to the Triatomini and Rhodniini tribes. Genetic diversities and phylogenetic topologies were compared with those obtained for the mitochondrial 16S rRNA and Cytochrome b (cyt b) genes, as well as for the D2 variable region of the ribosomal 28S rRNA gene. These results indicate that the EF-1α marker exhibits an intermediate level of diversity compared to mitochondrial and nuclear ribosomal genes, and that phylogenetic analysis based on EF-1α is highly informative for resolving deep phylogenetic relationships in Triatominae, such as tribe or genera.
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http://dx.doi.org/10.1016/j.meegid.2016.06.010DOI Listing
September 2016

Population differentiation of the Chagas disease vector Triatoma maculata (Erichson, 1848) from Colombia and Venezuela.

J Vector Ecol 2016 06;41(1):72-9

Grupo Grupo de Biología y Control de Enfermedades Infecciosas - BCEI, Universidad de Antioquia UdeA, Medellín, Antioquia, Colombia.

The emerging vector of Chagas disease, Triatoma maculata (Hemiptera, Reduviidae), is one of the most widely distributed Triatoma species in northern South America. Despite its increasing relevance as a vector, no consistent picture of the magnitude of genetic and phenetic diversity has yet been developed. Here, several populations of T. maculata from eleven Colombia and Venezuela localities were analyzed based on the morphometry of wings and the mitochondrial NADH dehydrogenase subunit 4 (ND4) gene sequences. Our results showed clear morphometric and genetic differences among Colombian and Venezuelan populations, indicating high intraspecific diversity. Inter-population divergence is suggested related to East Cordillera in Colombia. Analyses of other populations from Colombia, Venezuela, and Brazil from distinct eco-geographic regions are still needed to understand its systematics and phylogeography as well as its actual role as a vector of Chagas disease.
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http://dx.doi.org/10.1111/jvec.12196DOI Listing
June 2016

Multilocus analysis indicates that Trypanosoma cruzi I genetic substructure associated with sylvatic and domestic cycles is not an attribute conserved throughout Colombia.

Infect Genet Evol 2016 Mar 26;38:35-43. Epub 2015 Nov 26.

Grupo de Biología y Control de Enfermedades Infecciosas, BCEI, Universidad de Antioquia, Medellín, Colombia. Electronic address:

Trypanosoma cruzi, the causative agent of Chagas disease, has been classified into six discrete typing units (DTUs) named TcI to TcVI. Furthermore, subcontinental scale studies based on analysis of the splice leader intergenic region (SL-IR) of the mini-exon gene have subdivided TcI in five genetic groups (Ia-Ie) related to the domestic and non-domestic cycles. However, a current review of this marker among all the sequences deposited in the GenBank demonstrates no correlation between the genetic structure and the eco-epidemiological features of parasite transmission. In this study, we performed a multilocus analysis of TcI isolates from a diverse array of hosts and vectors in a wide eco-geographical area of Colombia. Sequences from SL-IR and mitochondrial cyt b genes as well as PCR-RFLP profiles for four nuclear genes were analyzed. Multilocus analysis indicates that genetic structuration associated with sylvatic and domestic cycles in Colombia is not an attribute conserved across the entire eco-geography where TcI can be found.
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http://dx.doi.org/10.1016/j.meegid.2015.11.026DOI Listing
March 2016

Eco-epidemiological study of an endemic Chagas disease region in northern Colombia reveals the importance of Triatoma maculata (Hemiptera: Reduviidae), dogs and Didelphis marsupialis in Trypanosoma cruzi maintenance.

Parasit Vectors 2015 Sep 22;8:482. Epub 2015 Sep 22.

Grupo BCEI, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellin, Colombia.

Background: In Colombia, Rhodnius prolixus and Triatoma dimidiata are the main domestic triatomine species known to transmit T. cruzi. However, there are multiple reports of T. cruzi transmission involving secondary vectors. In this work, we carried out an eco-epidemiological study on Margarita Island, located in the Caribbean region of Colombia, where Chagas disease is associated with non-domiciliated vectors.

Methods: To understand the transmission dynamics of Trypanosoma cruzi in this area, we designed a comprehensive, multi-faceted study including the following: (i) entomological evaluation through a community-based insect-surveillance campaign, blood meal source determination and T. cruzi infection rate estimation in triatomine insects; (ii) serological determination of T. cruzi prevalence in children under 15 years old, as well as in domestic dogs and synanthropic mammals; (iii) evaluation of T. cruzi transmission capacity in dogs and Didelphis marsupialis, and (iv) genetic characterization of T. cruzi isolates targeting spliced-leader intergene region (SL-IR) genotypes.

Results: Out of the 124 triatomines collected, 94% were Triatoma maculata, and 71.6% of them were infected with T. cruzi. Blood-meal source analysis showed that T. maculata feeds on multiple hosts, including humans and domestic dogs. Serological analysis indicated 2 of 803 children were infected, representing a prevalence of 0.25%. The prevalence in domestic dogs was 71.6% (171/224). Domestic dogs might not be competent reservoir hosts, as inferred from negative T. cruzi xenodiagnosis and haemoculture tests. However, 61.5% (8/13) of D. marsupialis, the most abundant synanthropic mammal captured, were T. cruzi-positive on xenodiagnosis and haemocultures.

Conclusions: This study reveals the role of peridomestic T. maculata and dogs in T. cruzi persistence in this region and presents evidence that D. marsupialis are a reservoir mediating peridomestic-zoonotic cycles. This picture reflects the complexity of the transmission dynamics of T. cruzi in an endemic area with non-domiciliated vectors where active human infection exists. There is an ongoing need to control peridomestic T. maculata populations and to implement continuous reservoir surveillance strategies with community participation.
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http://dx.doi.org/10.1186/s13071-015-1100-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4580378PMC
September 2015

Ecological niche and geographic distribution of the Chagas disease vector, Triatoma dimidiata (Reduviidae: Triatominae): Evidence for niche differentiation among cryptic species.

Infect Genet Evol 2015 Dec 29;36:15-22. Epub 2015 Aug 29.

Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA.

The principal vector of Chagas disease in Central America, Triatoma dimidiata, shows considerable diversity of habitat, phenotype, and genotype across its geographic range (central Mexico to southern Ecuador), suggesting that it constitutes a complex of cryptic species. However, no consistent picture of the magnitude of ecological differentiation among populations of this complex has yet been developed. To assess ecological variation across the complex, we broadened the geographic coverage of phylogeographic data and analyses for the complex into Colombia and Mexico, with additional nuclear (ITS-2) and mitochondrial (ND4) DNA sequences. This information allowed us to describe distributions of previously documented clades in greater detail: Group I, from central Guatemala south to Ecuador; Group II, across Mexico south through the Yucatán Peninsula to Belize and northern Guatemala; and Group III, in northern Guatemala, Belize, and the Yucatán Peninsula. Using ecological niche modeling, we assessed ecological niche differentiation among the groups using four hypotheses of accessible areas (M) across the distribution of the complex. Results indicated clear niche divergence of Group I from Group II: the speciation process thus appears to have involved genetic and ecological changes, suggesting divergence in populations in response to environmental conditions.
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http://dx.doi.org/10.1016/j.meegid.2015.08.035DOI Listing
December 2015

Spatio-temporal distribution of Aedes aegypti (Diptera: Culicidae) mitochondrial lineages in cities with distinct dengue incidence rates suggests complex population dynamics of the dengue vector in Colombia.

PLoS Negl Trop Dis 2015 Apr 20;9(4):e0003553. Epub 2015 Apr 20.

Grupo Biología y Control de Enfermedades Infecciosas-BCEI, Universidad de Antioquia UdeA, Medellín, Colombia.

Background: Aedes aegypti is the primary vector of the four serotypes of dengue virus (DENV1-4), Chikungunya and yellow fever virus to humans. Previous population genetic studies have revealed a particular genetic structure among the vector populations in the Americas that suggests differences in the ability to transmit DENV. In Colombia, despite its high epidemiologic importance, the genetic population structure and the phylogeographic depiction of Ae. aegypti, as well as its relationship with the epidemiologic landscapes in cities with heterogeneous incidence levels, remains unknown. We conducted a spatiotemporal analysis with the aim of determining the genetic structure and phylogeography of Colombian populations of Ae. aegypti among cities with different eco-epidemiologic characteristics with regard to DENV.

Methods/findings: Mitochondrial cytochrome oxidase C subunit 1 (COI)--NADH dehydrogenase subunit 4 (ND4) genes were sequenced and analyzed from 341 adult mosquitoes collected during 2012 and 2013 in the Colombian cities of Bello, Riohacha and Villavicencio, which exhibit low, medium and high levels of incidence of DENV, respectively. The results demonstrated a low genetic differentiation over time and a high genetic structure between the cities due to changes in the frequency of two highly supported genetic groups. The phylogeographic analyses indicated that one group (associated with West African populations) was found in all the cities throughout the sampling while the second group (associated with East African populations) was found in all the samples from Bello and in only one sampling from Riohacha. Environmental factors such as the use of chemical insecticides showed a significant correlation with decreasing genetic diversity, indicating that environmental factors affect the population structure of Ae. aegypti across time and space in these cities.

Conclusions: Our results suggest that two Ae. aegypti lineages are present in Colombia; one that is widespread and related to a West African conspecific, and a second that may have been recently introduced and is related to an East African conspecific. The first lineage can be found in cities showing a high incidence of dengue fever and the use of chemical insecticides, whereas the second is present in cities showing a low incidence of dengue fever where the use of chemical insecticides is not constant. This study helps to improve our knowledge of the population structure of Ae. aegypti involved in the diversity of dengue fever epidemiology in Colombia.
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http://dx.doi.org/10.1371/journal.pntd.0003553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4403987PMC
April 2015

Eco-epidemiology of Chagas disease in an endemic area of Colombia: risk factor estimation, Trypanosoma cruzi characterization and identification of blood-meal sources in bugs.

Am J Trop Med Hyg 2014 Dec 20;91(6):1116-24. Epub 2014 Oct 20.

Grupo Biología y Control de Enfermedades Infecciosas - BCEI, Universidad de Antioquia UdeA, Medellín, Colombia.

The Sierra Nevada de Santa Marta (SNSM) is a mountainous area in Colombia that is highly endemic to Chagas disease. We explored some eco-epidemiological attributes involved in the Chagas disease transmission scenario in three Indigenous communities. An epidemiological survey was done, where parasite infection in reservoirs and insects, Trypanosoma cruzi genotyping, identification of blood-meal sources in intradomiciliary insects using the high-resolution melting technique, and some risk factors were evaluated. The results suggest that several dwelling conditions such as thatched palm roofs and mud walls carried the highest risk of finding intradomiciliary Rhodnius prolixus, which 56.41% were infected with T. cruzi and fed with human blood. Moreover, T. cruzi Ia was the most frequent haplotype found in insects. These results indicate the existence of a domestic T. cruzi transmission cycle that does not overlap with the sylvatic cycle, and highlight the need for efficient entomological control focused to this area.
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http://dx.doi.org/10.4269/ajtmh.14-0112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4257632PMC
December 2014

Molecular evidence of demographic expansion of the chagas disease vector Triatoma dimidiata (Hemiptera, Reduviidae, Triatominae) in Colombia.

PLoS Negl Trop Dis 2014 Mar 13;8(3):e2734. Epub 2014 Mar 13.

Grupo BCEI, Universidad de Antioquia UdeA, Medellín, Colombia.

Background: Triatoma dimidiata is one of the most significant vectors of Chagas disease in Central America and Colombia, and, as in most species, its pattern of genetic variation within and among populations is strongly affected by its phylogeographic history. A putative origin from Central America has been proposed for Colombian populations, and high genetic differentiation among three biographically different population groups has recently been evidenced. Analyses based on putatively neutral markers provide data from which past events, such as population expansions and colonization, can be inferred. We analyzed the genealogies of the nicotinamide adenine dinucleotide dehydrogenase 4 (ND4) and the cytochrome oxidase subunit 1-mitochondrial genes, as well as partial nuclear ITS-2 DNA sequences obtained across most of the eco-geographical range in Colombia, to assess the population structure and demographic factors that may explain the geographical distribution of T. dimidiata in this country.

Results: The population structure results support a significant association between genetic divergence and the eco-geographical location of population groups, suggesting that clear signals of demographic expansion can explain the geographical distribution of haplotypes of population groups. Additionally, empirical date estimation of the event suggests that the population's expansion can be placed after the emergence of the Panama Isthmus, and that it was possibly followed by a population fragmentation process, perhaps resulting from local adaptation accomplished by orographic factors such as geographical isolation.

Conclusion: Inferences about the historical population processes in Colombian T. dimidiata populations are generally in accordance with population expansions that may have been accomplished by two important biotic and orographic events such as the Great American Interchange and the uplift of the eastern range of the Andes mountains in central Colombia.
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http://dx.doi.org/10.1371/journal.pntd.0002734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3953067PMC
March 2014

Genetic, cytogenetic and morphological trends in the evolution of the Rhodnius (Triatominae: Rhodniini) trans-Andean group.

PLoS One 2014 3;9(2):e87493. Epub 2014 Feb 3.

Grupo BCEI, Universidad de Antioquia UdeA, Medellin, Antioquia, Colombia.

The Rhodnius Pacific group is composed of three species: Rhodnius pallescens, R. colombiensis and R. ecuadoriensis, which are considered important vectors of trypanosomes (Trypanosoma cruzi and T. rangeli) infecting humans. This group is considered as a recent trans-Andean lineage derived from the widespread distributed sister taxa R. pictipes during the later uplift of northern Andes mountain range. The widest spread species R. pallescens may be a complex of two divergent lineages with different chromosomal attributes and a particular biogeographical distribution across Central America and Colombia with several southern populations in Colombia occupying the same sylvatic habitat as its sister species R. colombiensis. Although the taxonomy of Rhodnius Pacific group has been well studied, the unresolved phylogenetic and systematic issues are the target of this paper. Here we explore the molecular phylogeography of this species group analyzing two mitochondrial (ND4 and cyt b) and one nuclear (D2 region of ribosomal 28S gene) gene sequences. The molecular analyses suggest an early divergence of the species R. ecuadoriensis and R. colombiensis, followed by a recent expansion of R. pallescens lineages. The phylogenetic relationship between sympatric R. pallescens Colombian lineage and R. colombiensis was further explored using wing morphometry, DNA genome size measurements, and by analyzing chromosomal behavior of hybrids progeny obtained from experimental crosses. Our results suggest that the diversification of the two R. pallescens lineages was mainly influenced by biogeographical events such as (i) the emergence of the Panama Isthmus, while the origin and divergence of R. colombiensis was associated with (ii) the development of particular genetic and chromosomal features that act as isolation mechanisms from its sister species R. pallescens (Colombian lineage). These findings provide new insights into the evolution of the Rhodnius Pacific group and the underlying biological processes that occurred during its divergence.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0087493PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3911991PMC
December 2014

Eco-geographical differentiation among Colombian populations of the Chagas disease vector Triatoma dimidiata (Hemiptera: Reduviidae).

Infect Genet Evol 2013 Dec 11;20:352-61. Epub 2013 Sep 11.

Grupo BCEI, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellin, Colombia. Electronic address:

Triatoma dimidiata is currently the main vector of Chagas disease in Mexico, most Central American countries and several zones of Ecuador and Colombia. Although this species has been the subject of several recent phylogeographic studies, the relationship among different populations within the species remains unclear. To elucidate the population genetic structure of T. dimidiata in Colombia, we analyzed individuals from distinct geographical locations using the cytochrome c oxidase subunit 1 gene and 7 microsatellite loci. A clear genetic differentiation was observed among specimens from three Colombian eco-geographical regions: Inter Andean Valleys, Caribbean Plains and Sierra Nevada de Santa Marta mountain (SNSM). Additionally, evidence of genetic subdivision was found within the Caribbean Plains region as well as moderate gene flow between the populations from the Caribbean Plains and SNSM regions. The genetic differentiation found among Colombian populations correlates, albeit weakly, with an isolation-by-distance model (IBD). The genetic heterogeneity among Colombian populations correlates with the eco-epidemiological and morphological traits observed in this species across regions within the country. Such genetic and epidemiological diversity should be taken into consideration for the development of vector control strategies and entomological surveillance.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4705547PMC
http://dx.doi.org/10.1016/j.meegid.2013.09.003DOI Listing
December 2013

Phylogeographic pattern and extensive mitochondrial DNA divergence disclose a species complex within the Chagas disease vector Triatoma dimidiata.

PLoS One 2013 5;8(8):e70974. Epub 2013 Aug 5.

Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz - Fiocruz, Rio de Janeiro, Brazil.

Background: Triatoma dimidiata is among the main vectors of Chagas disease in Latin America. However, and despite important advances, there is no consensus about the taxonomic status of phenotypically divergent T. dimidiata populations, which in most recent papers are regarded as subspecies.

Methodology And Findings: A total of 126 cyt b sequences (621 bp long) were produced for specimens from across the species range. Forty-seven selected specimens representing the main cyt b clades observed (after a preliminary phylogenetic analysis) were also sequenced for an ND4 fragment (554 bp long) and concatenated with their respective cyt b sequences to produce a combined data set totalling 1175 bp/individual. Bayesian and Maximum-Likelihood phylogenetic analyses of both data sets (cyt b, and cyt b+ND4) disclosed four strongly divergent (all pairwise Kimura 2-parameter distances >0.08), monophyletic groups: Group I occurs from Southern Mexico through Central America into Colombia, with Ecuadorian specimens resembling Nicaraguan material; Group II includes samples from Western-Southwestern Mexico; Group III comprises specimens from the Yucatán peninsula; and Group IV consists of sylvatic samples from Belize. The closely-related, yet formally recognized species T. hegneri from the island of Cozumel falls within the divergence range of the T. dimidiata populations studied.

Conclusions: We propose that Groups I-IV, as well as T. hegneri, should be regarded as separate species. In the Petén of Guatemala, representatives of Groups I, II, and III occur in sympatry; the absence of haplotypes with intermediate genetic distances, as shown by multimodal mismatch distribution plots, clearly indicates that reproductive barriers actively promote within-group cohesion. Some sylvatic specimens from Belize belong to a different species - likely the basal lineage of the T. dimidiata complex, originated ~8.25 Mya. The evidence presented here strongly supports the proposition that T. dimidiata is a complex of five cryptic species (Groups I-IV plus T. hegneri) that play different roles as vectors of Chagas disease in the region.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070974PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733668PMC
March 2014

Chromosomal divergence and evolutionary inferences in Rhodniini based on the chromosomal location of ribosomal genes.

Mem Inst Oswaldo Cruz 2013 May;108(3)

Universidad de la República, Facultad de Ciencias, Sección Genética Evolutiva, Montevideo, Uruguay.

In this study, we used fluorescence in situ hybridisation to determine the chromosomal location of 45S rDNA clusters in 10 species of the tribe Rhodniini (Hemiptera: Reduviidae: Triatominae). The results showed striking inter and intraspecific variability, with the location of the rDNA clusters restricted to sex chromosomes with two patterns: either on one (X chromosome) or both sex chromosomes (X and Y chromosomes). This variation occurs within a genus that has an unchanging diploid chromosome number (2n = 22, including 20 autosomes and 2 sex chromosomes) and a similar chromosome size and genomic DNA content, reflecting a genome dynamic not revealed by these chromosome traits. The rDNA variation in closely related species and the intraspecific polymorphism in Rhodnius ecuadoriensis suggested that the chromosomal position of rDNA clusters might be a useful marker to identify recently diverged species or populations. We discuss the ancestral position of ribosomal genes in the tribe Rhodniini and the possible mechanisms involved in the variation of the rDNA clusters, including the loss of rDNA loci on the Y chromosome, transposition and ectopic pairing. The last two processes involve chromosomal exchanges between both sex chromosomes, in contrast to the widely accepted idea that the achiasmatic sex chromosomes of Heteroptera do not interchange sequences.
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http://dx.doi.org/10.1590/S0074-02762013000300017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005576PMC
May 2013

Morphometric and molecular evidence of intraspecific biogeographical differentiation of Rhodnius pallescens (HEMIPTERA: REDUVIIDAE: RHODNIINI) from Colombia and Panama.

Infect Genet Evol 2012 Dec 24;12(8):1975-83. Epub 2012 May 24.

Grupo de Biología y Control de Enfermedades Infecciosas - BCEI, Sede de Investigación Universitaria - SIU, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.

Rhodnius pallescens is considered the main vector of Chagas disease in Panama and a relevant secondary vector in northern Colombia. Previous data reported that this species presents cytogenetically heterogeneous populations, which are probably biogeographically segregated. To provide new information on the diversity of R. pallescens, we compared several populations from Colombia and Panama based on the morphometric analyses of wings, mitochondrial cytochrome b (cyt b) gene sequencing, and genomic DNA measurements. Although no differences in DNA amount were detected, significant differences in cyt b sequences as well as wing size and shape were identified among populations. The results obtained in this work indicate R. pallescens comprises two evolutionary lineages with genetic and morphological differences that could be explained by their geographic isolation in distinct ecological zones. These results provide new insight into R. pallescens population diversity and the underlying biological processes that shape its evolution.
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http://dx.doi.org/10.1016/j.meegid.2012.04.003DOI Listing
December 2012

Benznidazole-resistance in Trypanosoma cruzi is a readily acquired trait that can arise independently in a single population.

J Infect Dis 2012 Jul 2;206(2):220-8. Epub 2012 May 2.

Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, University of London, United Kingdom.

Benznidazole is the frontline drug used against Trypanosoma cruzi, the causative agent of Chagas disease. However, treatment failures are often reported. Here, we demonstrate that independently acquired mutations in the gene encoding a mitochondrial nitroreductase (TcNTR) can give rise to distinct drug-resistant clones within a single population. Following selection of benznidazole-resistant parasites, all clones examined had lost one of the chromosomes containing the TcNTR gene. Sequence analysis of the remaining TcNTR allele revealed 3 distinct mutant genes in different resistant clones. Expression studies showed that these mutant proteins were unable to activate benznidazole. This correlated with loss of flavin mononucleotide binding. The drug-resistant phenotype could be reversed by transfection with wild-type TcNTR. These results identify TcNTR as a central player in acquired resistance to benznidazole. They also demonstrate that T. cruzi has a propensity to undergo genetic changes that can lead to drug resistance, a finding that has implications for future therapeutic strategies.
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http://dx.doi.org/10.1093/infdis/jis331DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3379838PMC
July 2012

High-resolution melting (HRM) of the cytochrome B gene: a powerful approach to identify blood-meal sources in Chagas disease Vectors.

PLoS Negl Trop Dis 2012 28;6(2):e1530. Epub 2012 Feb 28.

Grupo Biología y Control de Enfermedades Infecciosas (BCEI), Sede de Investigación Universitaria, Universidad de Antioquia, Medellín, Colombia.

Methods to determine blood-meal sources of hematophagous Triatominae bugs (Chagas disease vectors) are serological or based on PCR employing species-specific primers or heteroduplex analysis, but these are expensive, inaccurate, or problematic when the insect has fed on more than one species. To solve those problems, we developed a technique based on HRM analysis of the mitochondrial gene cytochrome B (Cyt b). This technique recognized 14 species involved in several ecoepidemiological cycles of the transmission of Trypanosoma cruzi and it was suitable with DNA extracted from intestinal content and feces 30 days after feeding, revealing a resolution power that can display mixed feedings. Field samples were analyzed showing blood meal sources corresponding to domestic, peridomiciliary and sylvatic cycles. The technique only requires a single pair of primers that amplify the Cyt b gene in vertebrates and no other standardization, making it quick, easy, relatively inexpensive, and highly accurate.
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http://dx.doi.org/10.1371/journal.pntd.0001530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3289613PMC
June 2012

Morphometric and molecular differentiation of a Rhodnius robustus-like form from R. robustus Larousse, 1927 and R. prolixus Stal, 1859 (Hemiptera, Reduviidae).

Acta Trop 2011 Oct-Nov;120(1-2):103-9. Epub 2011 Jul 6.

Facultad de Ciencias, Universidad Nacional de Colombia, Medellín, Colombia, USA.

In Triatominae, "robustus" group constitutes a cluster of species with great haplotypic divergences but high similarities at morphological and nuclear DNA levels. Given these similarities, species identification generates a frequently problematic issue. In northwestern Amazonia, Rhodnius robustus cohabit with an apparently new species, cryptic with R. robustus (Abad-Franch and Monteiro, 2005). In this region (municipality of Puerto Asís, Department of Putumayo, Colombia), we collected insects classified as R. robustus by traditional keys. We compared this sample with specimens of R. robustus from Venezuela, and of R. prolixus from Colombia and Venezuela. The comparisons used landmark-based geometric morphometrics, and analyses of mitochondrial cytochrome b gene and of D2 variable region of the 28S RNA. The shape of the wings from Puerto Asís specimens disclosed clear-cut divergence from the shape of the wings as found for R. prolixus specimens from Venezuela and Colombia, and diverged from the shape of R. robustus from Venezuela. Thus, morphometric analyses suggested that the Puerto Asís collection could represent a new taxon. Using R. pallescens as an outgroup, a tentative phylogenetic tree based on the geometry of the wing showed the Rhodnius from Puerto Asís more similar to the R. prolixus from Colombia than their congeners from Venezuela. In contrast, the molecular classification clustered Colombian R. prolixus and Venezuelan R. robustus with published GenBank sequences, but it gave the insects from Puerto Asís a basal position to the "robustus" group. This outcome suggests that the Puerto Asís haplotype could be the one found by Abad-Franch and Monteiro (2005). Thus, both morphometric and molecular markers used here, although differing in the phylogenetic classification of samples, could differentiate the Puerto Asís sample from the morphologically similar R. prolixus and R. robustus. This could represent a valuable help in the entomological surveillance related to the control of Chagas disease in the South of Colombia and North of Ecuador.
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http://dx.doi.org/10.1016/j.actatropica.2011.06.009DOI Listing
March 2012

[Distribution and ecoepidemiology of the triatomine fauna (Hemiptera: Reduviidae) in Margarita Island, Bolívar, Colombia].

Biomedica 2010 Jul-Sep;30(3):382-9

Grupo de Biología y Control de Enfermedades Infecciosas, BCEI, Sede de Investigación Universitaria, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.

Introduction: Information concerning to triatomine diversity and some eco-epidemiologic aspects on Margarita Island has been recorded only from two of the five counties on the island. Knowledge about species habitat and their natural infection is essential to establish the risk for Chagas disease in endemic areas.

Objective: The distribution of triatomine insect fauna and its infection with Trypanosoma cruzi was described in order to establish and to stratify the risk of Chagas disease transmission.

Material And Methods: Each of the 5 counties on Margarita Island were surveyed for triatomid insects inside and outside each dwelling. In the extradomicilary area, searches were conducted in the palms and bird nests located within forests and in pastures near domiciles. Infection with T. cruzi was determined amplifying by PCR the DNA extracted from triatomine feces.

Results: Five species of Reduviidae were recovered among the 1,154 triatomines captured in the 5 counties. Triatoma maculata and Rhodnius pallescens showed high infection rates within dwellings and as well as in the peridomestic areas in Mompós and Talaigua Nuevo. On the palm trees, only R. pallescens and Eratyrus cuspidatus were found infected, and only in San Fernando and Margarita. In Cicuco, only R. pallescens was infected. Presence of Triatoma dimidiata was also ascertained.

Conclusion: Infected triatomines were present in houses and on palm trees in all counties on the island. These observations indicate a potential risk of Chagas across the entire island; furthermore the presence of T. dimidiata, a very efficient Chagas vector, emphasizes the need to establish its epidemiological status on the island.
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October 2011

[Genetic differentiation of three Colombian populations of Triatoma dimidiata (Heteroptera: Reduviidae) by ND4 mitochondrial gene molecular analysis].

Biomedica 2010 Apr-Jun;30(2):207-14

Grupo de Biología y Control de Enfermedades Infecciosas, Sede de Investigación Universitaria, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.

Introduction: Triatoma dimidiata is the second most important vector of Chagas disease in Colombia after Rhodnius prolixus. Population genetic studies are essential for the adequate design and implementation of vector control and surveillance strategies.

Objective: The level of genetic variability and population differentiation was surveyed among three Colombian populations of T. dimidiata from different geographic locations and ecotopes, using ND4 mitochondrial gene.

Materials And Methods: Genetic comparison was made between two wild populations from La Guajira (n=10) and Santander (n=10) provinces, and one intra (n=15) and one peridomiciliary (n=5) population from the Cesar province. The polymorphism frequencies of the ND4 mitochondrial gene sequence were analyzed to deduce population structure based on the 40 samples.

Results: Colombian T. dimidiata showed a high nucleotide (π: 0.034) and haplotype diversity (Hd: 0.863), as well as significant population subdivision (fST: 0.761) and a low migration rate (Nm: 0.157). Genetic distances and variability differences among populations indicate distinct population subdivision amongst the three provinces.

Conclusion: ND4 proved useful in elucidating the significant genetic differentiation that has occurred among T. dimidiata populations from La Guajira, Cesar and Santander. The analysis suggested a relationship between population subdivision and some eco-epidemiological attributes of this vector from the central eastern and northwestern regions of Colombia.
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February 2011

Chromosome variability in the Chagas disease vector Rhodnius pallescens (Hemiptera, Reduviidae, Rhodniini).

Mem Inst Oswaldo Cruz 2008 Mar;103(2):160-4

Grupo de Chagas, Sede de Investigación Universitaria, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.

Rhodnius pallescens is the main vector of Trypanosoma cruzi in Panama and one of the most relevant secondary vectors in Colombia. Despite the importance of this species, there is limited knowledge about the genetic variability along its geographical distribution. In order to evaluate the degree of karyotype variability we analyzed the meiotic behavior and banding pattern of the chromosomes of 112 males of R. pallescens coming from different regions of Colombia and Panama. Using the C-banding technique we identified two chromosomal patterns or cytotypes characterized by differences in the amount, size and distribution of constitutive heterochromatic regions in the chromosome complement (2n = 20 autosomes plus XY in males). The individuals can be easily classified in each cytotype by the analysis of the chromosomes during first meiotic prophase. The frequencies of the cytotypes are variable according to the geographic origin of the populations. This chromosomal divergence together with morphological data supports the existence of three genetically different populations of R. pallescens and provides new information to understand the distribution dynamics of this species.
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http://dx.doi.org/10.1590/s0074-02762008000200006DOI Listing
March 2008