Search

Background and AimsThe Mediterranean-type forest of central Chile is considered a ‘biodiversity hotspot’ and a relic of a wider ancient distribution produced by past climatic oscillations. Nothofagus macrocarpa, commonly known as ‘roble de Santiago’, is a threatened palaeoendemic of this forest, poorly represented in the protected area system. This tree has been repeatedly misidentified as the sister species N. obliqua, which has affected its recognition and protection. Only a few populations of N. macrocarpa remain within a matrix of intensive land use that has been affected by recent forest fires. We tested the hypothesis that current populations of N. macrocarpa are a relic state of a previously widespread range, with the aim of contributing to its identification, its biogeographical history and the design of conservation measures using genetic information.MethodsWe analysed remnant N. macrocarpa forests using nuclear (nDNA) and chloroplast DNA (cpDNA) sequences, conducted phylogenetic and phylogeographical analyses to reconstruct its biogeographical history, and assessed microsatellites [simple sequence repeats (SSRs)] to determine contemporary patters of diversity within and among all remnant populations. We also examined the degree of past, current and potential future isolation of N. macrocarpa populations using ecological niche models (ENMs).Key ResultsThe species N. macrocarpa was confirmed by nDNA sequences, as previously suggested by chromosomal analysis. Small isolated populations of N. macrocarpa exhibited moderate to high genetic diversity according to SSRs. cpDNA analysis revealed a marked past latitudinal geographical structure, whereas analysis of SSRs did not find such current structure. ENM analyses revealed local expansion–contraction of the N. macrocarpa range during warmer periods, particularly in the northern and central ranges where basal-most cpDNA haplotypes were detected, and recent expansion to the south of the distribution.ConclusionsGenetic patterns confirm that N. macrocarpa is a distinct species and suggest a marked latitudinal relic structure in at least two evolutionarily significant units, despite contemporary among-population gene flow. This information must be considered when choosing individuals (seeds and/or propagules) for restoration purposes, to avoid the admixture of divergent genetic stocks.

Paratuberculosis is a worldwide chronic enteric disease of ruminants, caused by Mycobacterium avium subsp. paratuberculosis (MAP). While MAP has been widely investigated all around the world, little is known about the different strains that circulate in each country. This study describes the genetic diversity of MAP isolates from different bovine and deer herds from Argentina, analyzed by Multiple-Locus Variable number tandem repeat Analysis (MLVA), as well as the phylogenetic relatedness between geographically distant isolates through Whole Genome Sequencing (WGS) and core-genome analysis. A total of 90 MAP isolates were analyzed. The results showed seven different MLVA genotypes, with almost 75% of them belonging to pattern INMV 1, described in all the herds studied. WGS results suggested the presence of a common INMV 1 strain circulating throughout the country. Our results allow confirming the coexistence of different strains in time and space and the mixed infections identified in some animals. These observations suggest the absence of animal monitoring prior to introduction to the herds and the need for a control program in the country. This study represents the first to report WGS of MAP strains in Argentina.

‘Mosca de la bichera’ or simply ‘bichera’ are common names given in Uruguay and the region to the primary myiasis-causing species Cochliomyia hominivorax, the New World Screwworm (NWS) fly (Diptera: Calliphoridae). Myiasis happens when dipteran larvae infest live animals at least during some developmental phase to feed on host’s flesh and fluids. For the NWS fly it is mandatory that all three larvae phases develop on living tissues of warm-blooded vertebrates, including humans. Unsurprisingly, this parasitic behavior causes great profit losses to the livestock industry and is also considered a neglected public health issue. NWS is endemic from the tropics and subtropics of the Americas, but has been eradicated from North and Central America through a Sterile Insect Technique (SIT) based Area Wide – Integrated Pest Management (AW-IPM) program that lasted more than 50 years. Since 2004, a permanent barrier is actively maintained in Darien, along the Panama-Colombian border, by releasing 14 million sterile flies per week to avoid reintroductions. Due to its direct and indirect impact on the national economy, the logistic complexity and the cost of SIT control programs, much discussion is underway in Uruguay about NWS fly eradication. Direct economic losses due to myiasis in Uruguay oscillate between USD 40 and 154 million annually (i.e., between 2-8% of livestock Gross Domestic Product, GDP). Currently, the Food and Agriculture Organization of the UN/International Atomic Energy Agency (FAO/IAEA) and the US Department of Agriculture/Panama United States Commission for the Eradication and Prevention of Screwworm/ Ministry of Livestock, Agriculture and Fisheries (USDA/COPEG/MGAP) have been working on eradication proposals for Uruguay. Cost-benefit analysis of each group concluded that a net present value of around USD 98 million and USD 146 million could be achieved, respectively, supporting the positive impact of NWS fly eradication at local farmers and the whole livestock sector levels. The main challenge of this endeavor is to find a way to keep the myiasis-free status of Uruguay in case that its neighbors, Argentina and Brazil, do not engage in a similar program, at least for their southernmost region. Here we review the bulk of bibliography produced since the beginning of NWS eradication programs in North America during the 40s decade, its life cycle and parasitic lifestyle as well as many aspects of its population genetics and ecology. We further discuss promising biotechnological approaches under active development based on transgenesis and CRISPR/Cas genome-editing, that are considered the new avenue in insect-control strategies. Balance among innovation and regulation framework is considered based on lessons learned. Currently, a CRISPR/Cas gene editing strategy for gene drive is being investigated in Uruguay, a development conducted with national funds, what guarantees its complete control and local institutions, authorities and ultimately livestock producers can be the biotechnology owners. Finally, we highlight the know-how that will be generated opening the possibility to locally develop new genetic-based control strategies for other parasites and/or vector insects of high veterinary and public health relevance.

Red-banded stink bug

Neospora caninum causes neosporosis, a leading cause of bovine abortion worldwide. Uruguay is a developing economy in South America that produces milk to feed seven times its population annually. Naturally, dairy production is paramount to the country's economy, and bovine reproductive failure impacts it profoundly. Recent studies demonstrated that the vast majority of infectious abortions in dairy cows are caused by N. caninum. To delve into the local situation and contextualize it within the international standing, we set out to characterize the Uruguayan N. caninum strains. For this, we isolated four distinct strains and determined by microsatellite typing that these represent three unique genetic lineages, distinct from those reported previously in the region or elsewhere. An unbiased analysis of the current worldwide genetic diversity of N. caninum strains known, whereby six typing clusters can be resolved, revealed that three of the four Uruguayan strains group closely with regional strains from Argentina and Brazil. The remaining strain groups in an unrelated genetic cluster, suggesting multiple origins of the local strains. Microsatellite typing of N. caninum DNA from fetuses opportunistically collected from local dairy farms correlated more often with one of the isolates. Overall, our results contribute to further understanding of genetic diversity among strains of N. caninum both regionally and worldwide.

Background Microbial communities present in environmental waters constitute a reservoir for antibiotic-resistant pathogens that impact human health. For this reason, a diverse variety of water environments are being analyzed using metagenomics to uncover public health threats. However, the composition of these communities along the coastal environment of a whole city, where sewage and beach waters are mixed, is poorly understood. Results We shotgun-sequenced 20 coastal areas from the city of Montevideo (capital of Uruguay) including beach and sewage water samples to characterize bacterial communities and their virulence and antibiotic resistance repertories. As expected, we found that sewage and beach environments present significantly different bacterial communities. This baseline allowed us to detect a higher prevalence and a more diverse repertory of virulence and antibiotic-resistant genes in sewage samples. Many of these genes come from well-known enterobacteria and represent carbapenemases and extended-spectrum betalactamases reported in hospital infections in Montevideo. Additionally, we were able to genotype the presence of both globally disseminated pathogenic clones and emerging antibiotic-resistant bacteria in sewage waters. Conclusions Our study represents the first in using metagenomics to jointly analyze beaches and the sewage system from an entire city, allowing us to characterize antibiotic-resistant pathogens circulating in urban waters. The data generated in this initial study represent a baseline metagenomic exploration to guide future longitudinal (time-wise) studies, whose systematic implementation will provide useful epidemiological information to improve public health surveillance., Microbiome, 7 (1), ISSN:2049-2618

Summary We present a global atlas of 4,728 metagenomic samples from mass-transit systems in 60 cities over 3 years, representing the first systematic, worldwide catalog of the urban microbial ecosystem. This atlas provides an annotated, geospatial profile of microbial strains, functional characteristics, antimicrobial resistance (AMR) markers, and genetic elements, including 10,928 viruses, 1,302 bacteria, 2 archaea, and 838,532 CRISPR arrays not found in reference databases. We identified 4,246 known species of urban microorganisms and a consistent set of 31 species found in 97% of samples that were distinct from human commensal organisms. Profiles of AMR genes varied widely in type and density across cities. Cities showed distinct microbial taxonomic signatures that were driven by climate and geographic differences. These results constitute a high-resolution global metagenomic atlas that enables discovery of organisms and genes, highlights potential public health and forensic applications, and provides a culture-independent view of AMR burden in cities., Graphical abstract, Highlights • Cities possess a consistent “core” set of non-human microbes • Urban microbiomes echo important features of cities and city-life • Antimicrobial resistance genes are widespread in cities • Cities contain many novel bacterial and viral species, This systematic, worldwide catalog of urban microbiomes represents a metagenomic atlas important for understanding the ecology, virulence, and antibiotic resistance of city-specific microbial communities.

Orientador: Ana Maria Lima de Azeredo-Espin Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia Resumo: A mosca-da-bicheira, Cochliomyia hominivorax, é um ectoparasito obrigatório dos animais de sangue quente endêmico das Américas. As miíases causadas por esta praga geram severos prejuízos econômicos na produção pecuária da América do Sul e da região do Caribe, devido à mortalidade e redução na produtividade dos animais infestados. Nesta tese, abordamos alguns aspectos da distribuição da variação de seqüências do DNA mitocondrial de C. hominivorax em duas escalas geográficas e os eventos históricos que podem explicar os padrões observados. As principais contribuições foram compiladas em três artigos científicos. No primeiro artigo, (artigo 1) investigamos o padrão geral de estruturação geográfica da variabilidade genética em 38 localidades ao longo de toda a distribuição da espécie. As análises das seqüências parciais da região controle (CR) e dos genes COI e COII mitocondriais revelaram que a diversidade genética da espécie está estruturada em quatro grupos regionais principais, denominados Cuba (CG), República Dominicana (DRG), região norte e região sul da Amazônia (NAG e SAG, respectivamente). Foi sugerido que o padrão observado foi principalmente formado por eventos históricos, como a colonização das ilhas do Caribe, vicariância na região Amazônica e expansão das populações desde o último máximo glacial. O segundo artigo (artigo 2) apresenta um teste da hipótese de perturbação-vicariância na região Amazônica, que foi realizado através de simulações de coalescência e modelagem ecológica da espécie. Os resultados indicaram que os ciclos climáticos do Pleistoceno promoveram a expansão, fragmentação e mistura das populações na região Amazônica em diferentes momentos do passado. Detectamos que o primeiro momento de divergência dos grupos de populações analisadas (SAG, NAG e amostras da América Central e do Norte) é mais antigo que o último período glacial e deve ter acontecido no interglacial Yarmouth (~250.000 anos atrás). Porém, a demografia histórica da espécie e as relações filogenéticas das seqüências mitocondriais sugerem um padrão mais complexo, incluindo reticulação, para a evolução e divergência das populações na região Amazônica. No terceiro artigo (artigo 3), apresentamos o primeiro estudo da variabilidade genética de C. hominivorax em escala local, em que se analisaram indivíduos de 25 sítios de coleta distribuídos numa área de 90 km por 60 km próxima às cidades de Quaraí e Artigas, na fronteira entre Brasil e Uruguai. Os resultados sugerem que os indivíduos pertencem a uma única população com alto grau de polimorfismo, indicando que esta é uma população estável capaz de sobreviver às condições adversas do inverno local e que flutua demograficamente de acordo com o clima da região. Porém, há evidências de que estas amostras não estão em equilíbrio e, portanto, a ausência de estruturação baseada nas estimativas tradicionais deve ser interpretada com cuidado. Como esta é uma região importante para a atividade pecuária do Brasil e Uruguai, estes resultados são de interesse para um possível plano de controle na região. No entanto, serão necessárias análises de amostras seriadas ao longo de um ano, assim como de diferentes anos na mesma escala geográfica, para melhor entender o padrão de fluxo gênico na região Abstract: The New World screwworm fly, Cochliomyia hominivorax, is an obligate ectoparasite of warm blooded vertebrates, endemic of the Americas. Myiasis caused by this pest fly generate great profit looses to the livestock sector in South America and the Caribbean region, due to mortality and productivity reduction of infested animals. In this thesis, we approach some aspects of mitochondrial DNA sequences variation of C. hominivorax in two geographic scales, and the historical events that could explain the observed patterns. The main contributions were compiled in three research articles. In the first (article 1), we investigate the general pattern of genetic variability distribution in 38 localities encompassing the species geographic range. The analysis of partial sequences of the mitochondrial control region (CR), COI and COII genes revealed four main regional groups of genetic diversity, denominated Cuba (CG), Dominican Republic (DRG), north region (NAG) and south region (SAG) of the Amazon basin. Results suggest that current distribution of C. hominivorax genetic diversity was mainly shaped for historical events, i.e. Caribbean islands colonization, vicariance in the Amazon region and population expansion since the last glacial maximum. The second article (article 2) presents a hypotheses test of vicariance-perturbation in the Amazon region, through coalescent simulations and ecological niche modeling of the species. The results indicate that Pleistocene climatic cycles promote expansion, fragmentation and mixture of Amazon region populations during the past. We detected that the divergence among groups of analyzed populations (SAG, NAG and samples from North and Central America) occurred before the last glacial maximum and may have happened during the interglacial Yarmouth (~250.000 years ago). However, the species demographic history and the phylogenetic relationships of the mitochondrial sequences suggest a more complex pattern, including reticulation, for the evolution and divergence of the Amazonian region populations. Finally, in the third article (article 3) we present the first study of the genetic variability of C. hominivorax in a local scale, in which individuals of 25 localities in a 90 km for 60 km area in the proximity of Artigas city and Quaraí city, in the border between Brazil and Uruguay, were analyzed. The results suggest that the individuals are from a unique population, with high level of polymorphism, indicating that this is a stable population which is capable of survive the adverse local winter conditions and demographically fluctuate in accordance to the region climate. However, there are evidences that these samples are not in equilibrium hence the absence of structure interpretation based on traditional estimates must be done carefully. As this is an important region for livestock industry of Brazil and Uruguay, these results are interesting for a possible control program in the region. However, studies of serially collected samples throughout the year and in different years at the same geographic scale will be necessary to better understand the gene flow pattern in the region Doutorado Genética Animal e Evolução Doutor em Genética e Biologia Molecular

Conventional tillage and mineral fertilization (CTMF) jeopardize soil health in conventional vegetable production systems. Using a field experiment established in Uruguay in 2012, we aimed to compare the soil restoration potential of organic fertilization (compost and poultry manure) combined with conventional tillage and cover crop incorporated into the soil (CTOF) or with reduced tillage and the use of cover crop as mulch (RTOF). In 2017, table beet was cultivated under CTMF, CTOF and RTOF, and yields, soil aggregate composition and nutrients, as well as soil and table beet rhizosphere microbiota (here: bacteria and archaea) were evaluated. Microbiota was studied by high-throughput sequencing of 16S rRNA gene fragments amplified from total community DNA. RTOF exhibited higher soil aggregation, soil organic C, nutrient availability and microbial alpha-diversity than CTMF, and became more similar to an adjacent natural undisturbed site. The soil microbiota was strongly shaped by the fertilization source which was conveyed to the rhizosphere and resulted in differentially abundant taxa. However, 229 amplicon sequencing variants were found to form the core table beet rhizosphere microbiota shared among managements. In conclusion, our study shows that after only 5 years of implementation, RTOF improves soil health under intensive vegetable farming systems.

Background Streptococcus pneumoniae serotype 1 remains a leading cause of invasive pneumococcal diseases, even in countries with PCV-10/PCV-13 vaccine implementation. The main objective of this study, which is part of the Pneumococcal African Genome project (PAGe), was to determine the phylogenetic relationships of serotype 1 isolates recovered from children patients in Casablanca (Morocco), compared to these from other African countries; and to investigate the contribution of accessory genes and recombination events to the genetic diversity of this serotype. Results The genome average size of the six-pneumococcus serotype 1 from Casablanca was 2,227,119 bp, and the average content of coding sequences was 2113, ranging from 2041 to 2161. Pangenome analysis of the 80 genomes used in this study revealed 1685 core genes and 1805 accessory genes. The phylogenetic tree based on core genes and the hierarchical bayesian clustering analysis revealed five sublineages with a phylogeographic structure by country. The Moroccan strains cluster in two different lineages, the five invasive strains clusters altogether in a divergent clade distantly related to the non-invasive strain, that cluster with all the serotype 1 genomes from Africa. Conclusions The whole genome sequencing provides increased resolution analysis of the highly virulent serotype 1 in Casablanca, Morocco. Our results are concordant with previous works, showing that the phylogeography of S. pneumoniae serotype 1 is structured by country, and despite the small size (six isolates) of the Moroccan sample, our analysis shows the genetic cohesion of the Moroccan invasive isolates.

Seagrasses play a vital role in structuring coastal marine ecosystems, but their distributional range and genetic diversity have declined rapidly in recent decades. To improve conservation of seagrass species, it is important to predict how climate change may impact their ranges. Such predictions are typically made with correlative species distribution models (SDMs), which can estimate a species' potential distribution under present and future climatic scenarios given species' presence data and climatic predictor variables. However, these models are typically constructed with species-level data, and thus ignore intraspecific genetic variability, which can give rise to populations with adaptations to heterogeneous climatic conditions. Here, we explore the link between intraspecific adaptation and niche differentiation in Thalassia hemprichii, a seagrass broadly distributed in the tropical Indo-Pacific Ocean and a crucial provider of habitat for numerous marine species. By retrieving and re-analysing microsatellite data from previous studies, we delimited two distinct phylogeographical lineages within the nominal species and found an intermediate level of differentiation in their multidimensional environmental niches, suggesting the possibility for local adaptation. We then compared projections of the species' habitat suitability under climate change scenarios using species-level and lineage-level SDMs. In the Central Tropical Indo-Pacific region, models for both levels predicted considerable range contraction in the future, but the lineage-level models predicted more severe habitat loss. Importantly, the two modelling approaches predicted opposite patterns of habitat change in the Western Tropical Indo-Pacific region. Our results highlight the necessity of conserving distinct populations and genetic pools to avoid regional extinction due to climate change and have important implications for guiding future management of seagrasses. National Natural Science Foundation of China, Grant/Award Number: 31971395 and 41761144057; European Commission, Grant/ Award Number: H2020-MSCA-IF-2019 and 882221; Foundation for Science and Technology (FCT), Grant/Award Number: UID/Multi/04326/2019, PTDC/BIA-CBI/6515/2020 and DL57; Thailand Research Fund, Grant/Award Number: RDG6130002; Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research, Grant/ Award Number: 18K05780 info:eu-repo/semantics/submittedVersion

The New World screwworm (NWS) fly, Cochliomyia hominivorax (Diptera: Calliphoridae), is an economically important ectoparasite currently distributed in South America and in the Caribbean basin. The successful eradication of this species in USA, Mexico and continental Central America was achieved by a control program based on the sterile insect technique (SIT). In order to implement a genetic control strategy over the NWS fly&rsquo, s current area of occurrence, first, it is necessary to understand the species dynamics and population structure. In order to address this objective, the spatial genetic structure of the NWS fly was previously reported in South America based on different genetic markers, however, to date, no study has investigated temporal changes in the genetic composition of its populations. In the current study, the temporal genetic structure of a NWS fly population from Uruguay was investigated through two consecutive samplings from the same locality over an interval of approximately 18 generations. The genetic structure was accessed with neutral and under selection SNPs obtained with genotyping-by-sequencing. The results gathered with these data were compared to estimates achieved with mitochondrial DNA sequences and eight microsatellite markers. Temporal changes in the genetic composition were revealed by all three molecular markers, which may be attributed to seasonal changes in the NWS fly&rsquo, s southern distribution. SNPs were employed for the first time for estimating the genetic structure in a NWS fly population, these results provide new clues and perspectives on its population genetic structure. This approach could have significant implications for the planning and implementation of management programs.

Made available in DSpace on 2019-10-04T12:30:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The New World screwworm fly Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae) is an important livestock pest endemic to the Americas that has been eradicated from North and continental Central America with a control program based on the Sterile Insect Technique (SIT). The establishment of target management units is a strategic step in the implementation of new control programs, which can be achieved using genetic studies of natural populations. Previous studies of New World screwworm fly populations were conducted on the continental scale and identified four main groups: two in South America and two in the Caribbean. However, studies within these groups are needed to determine which smaller geographic areas can be treated as management units. Here, we analyze the genetic variability distribution and the population demographic signals of the New World screwworm fly in a 6,000 km(2) area located along the border of Brazil and Uruguay.This area was the subject of the first control pilot program conducted in South America. We studied eight microsatellite loci and sequences from two mitochondrial DNA regions in individuals sampled at 20-25 livestock breeding farms. We observed no population structure and found high genetic variability on the geographical scale sampled for both molecular markers. Our microsatellite data suggest that these populations are not in equilibrium, and demographic analyses based on mitochondrial data indicate population expansion.These results suggest that this geographic scale is not adequate for future New World screwworm fly management in South America. Univ Estadual Campinas, UNICAMP, Inst Biol, Dept Genet Evolucao Microbiol & Imunol, BR-13083970 Campinas, SP, Brazil Univ Estadual Campinas, UNICAMP, Programa Posgrad Genet & Biol Mol, BR-13083970 Campinas, SP, Brazil Univ Estadual Campinas, UNICAMP, Ctr Biol Mol & Engn Genet, Av Candido Rondon 400, BR-13083875 Campinas, SP, Brazil Inst Pasteur Montevideo, Unidad Bioinformat, Montevideo 11400, Uruguay Univ Estadual Paulista, Inst Biociencias, Dept Zool, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Zool, BR-13506900 Rio Claro, SP, Brazil CNPq: 578231/2008-5 MAPA CNPq: 141777/2014-1

Background Long-term survival in isolated marginal seas of the China coast during the late Pleistocene ice ages is widely believed to be an important historical factor contributing to population genetic structure in coastal marine species. Whether or not contemporary factors (e.g. long-distance dispersal via coastal currents) continue to shape diversity gradients in marine organisms with high dispersal capability remains poorly understood. Our aim was to explore how historical and contemporary factors influenced the genetic diversity and distribution of the brown alga Sargassum thunbergii, which can drift on surface water, leading to long-distance dispersal. Results We used 11 microsatellites and the plastid RuBisCo spacer to evaluate the genetic diversity of 22 Sargassum thunbergii populations sampled along the China coast. Population structure and differentiation was inferred based on genotype clustering and pairwise F ST and allele-frequency analyses. Integrated genetic analyses revealed two genetic clusters in S. thunbergii that dominated in the Yellow-Bohai Sea (YBS) and East China Sea (ECS) respectively. Higher levels of genetic diversity and variation were detected among populations in the YBS than in the ECS. Bayesian coalescent theory was used to estimate contemporary and historical gene flow. High levels of contemporary gene flow were detected from the YBS (north) to the ECS (south), whereas low levels of historical gene flow occurred between the two regions. Conclusions Our results suggest that the deep genetic divergence in S. thunbergii along the China coast may result from long-term geographic isolation during glacial periods. The dispersal of S. thunbergii driven by coastal currents may facilitate the admixture between southern and northern regimes. Our findings exemplify how both historical and contemporary forces are needed to understand phylogeographical patterns in coastal marine species with long-distance dispersal. Electronic supplementary material The online version of this article (10.1186/s12862-017-1089-6) contains supplementary material, which is available to authorized users.

Campylobacter hyointestinalis is an emerging pathogen currently divided in two subspecies: C. hyointestinalis subsp. lawsonii which is predominantly recovered from pigs, and C. hyointestinalis subsp. hyointestinalis which can be found in a much wider range of mammalian hosts. Despite C. hyointestinalis being reported as an emerging pathogen, its evolutionary and host-associated diversification patterns are still vastly unexplored. For this reason, we generated whole-genome sequences of 13 C. hyointestinalis subsp. hyointestinalis strains and performed a comprehensive comparative analysis including publicly available C. hyointestinalis subsp. hyointestinalis and C. hyointestinalis subsp. lawsonii genomes, to gain insight into the genomic variation of these differentially-adapted subspecies. Both subspecies are distinct phylogenetic lineages which present an apparent barrier to homologous recombination, suggesting genetic isolation. This is further supported by accessory gene patterns that recapitulate the core genome phylogeny. Additionally, C. hyointestinalis subsp. hyointestinalis presents a bigger and more diverse accessory genome, which probably reflects its capacity to colonize different mammalian hosts unlike C. hyointestinalis subsp. lawsonii that is presumably host-restricted. This greater plasticity in the accessory genome of C. hyointestinalis subsp. hyointestinalis correlates to a higher incidence of genome-wide recombination events, that may be the underlying mechanism driving its diversification. Concordantly, both subspecies present distinct patterns of gene families involved in genome plasticity and DNA repair like CRISPR-associated proteins and restriction-modification systems. Together, our results provide an overview of the genetic mechanisms shaping the genomes of C. hyointestinalis subspecies, contributing to understand the biology of Campylobacter species that are increasingly recognized as emerging pathogens.

BackgroundMicrobial communities present in environmental waters constitute a reservoir for antibiotic-resistant pathogens that impact human health. For this reason a diverse variety of water environments are being analyzed using metagenomics to uncover public health threats. However, the composition of these communities along the coastal environment of a whole city where sewage and beach waters are mixed, is poorly understood.ResultsWe shotgun-sequenced 20 coastal areas from the city of Montevideo (capital of Uruguay) including beach and sewage water samples to characterize bacterial communities and their virulence and antibiotic resistance repertories. We found that sewage and beach environments presented significantly different bacterial communities. Sewage waters harbored a higher prevalence and a more diverse repertory of virulence and antibiotic resistant genes mainly from well-known enterobacteria, including carbapenemases and extended-spectrum betalactamases reported in hospital infections in Montevideo. Additionally, we were able to genotype the presence of both globally-disseminated pathogenic clones as well as emerging antibiotic-resistant bacteria in sewage waters.ConclusionsOur study represents the first in using metagenomics to jointly analyze beaches and the sewage system from an entire city, allowing us to characterize antibiotic-resistant pathogens circulating in urban waters. The data generated in this initial study represent a baseline metagenomic exploration to guide future longitudinal (time-wise) studies, whose systematic implementation will provide useful epidemiological information to improve public health surveillance.

Activation-induced cytidine deaminase (AID) initiates somatic hypermutation and class switch recombination of the immunoglobulin genes. As a trade-off for its physiological function, AID also contributes to tumor development through its mutagenic activity. In chronic lymphocytic leukemia (CLL), AID is overexpressed in the proliferative fractions (PFs) of the malignant B lymphocytes, and its anomalous expression has been associated with a clinical poor outcome. Recent preclinical data suggested that ibrutinib and idelalisib, 2 clinically approved kinase inhibitors, increase AID expression and genomic instability in normal and neoplastic B cells. These results raise concerns about a potential mutagenic risk in patients receiving long-term therapy. To corroborate these findings in the clinical setting, we analyzed AID expression and PFs in a CLL cohort before and during ibrutinib treatment. We found that ibrutinib decreases the CLL PFs and, interestingly, also reduces AID expression, which correlates with dampened AKT and Janus Kinase 1 signaling. Moreover, although ibrutinib increases AID expression in a CLL cell line, it is unable to do so in primary CLL samples. Our results uncover a differential response to ibrutinib between cell lines and the CLL clone and imply that ibrutinib could differ from idelalisib in their potential to induce AID in treated patients. Possible reasons for the discrepancy between preclinical and clinical findings, and their effect on treatment safety, are discussed. Fil: Morande, Pablo Elías. Instituto Pasteur de Montevideo; Uruguay. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sivina, Mariela. University of Texas Health Science Center at Houston. University of Texas Md Anderson Cancer Center; Estados Unidos Fil: Uriepero, Angimar. Instituto Pasteur de Montevideo; Uruguay Fil: Seija, Noé. Instituto Pasteur de Montevideo; Uruguay Fil: Berca, Catalina. Instituto Pasteur de Montevideo; Uruguay Fil: Fresia, Pablo. Instituto Pasteur de Montevideo; Uruguay Fil: Landoni, Ana Inés. Ministerio de Salud.Hospital Maciel. Administración de los Servicios de Salud del Estado; Uruguay Fil: Di Noia, Javier M.. University of Montreal; Canadá. Cliniques de Montreal. Institut de Recherches. Division of Immunity and Viral Infections; Canadá Fil: Burger, Jan A.. University of Texas Health Science Center at Houston. University of Texas Md Anderson Cancer Center; Estados Unidos Fil: Oppezzo, Pablo. Instituto Pasteur de Montevideo; Uruguay

Mycobacterium tuberculosis strain MYC004 was isolated from a Mexican patient with tuberculous meningitis, the most aggressive form of tuberculosis. The draft genome sequence is the first of a meningeal strain of M. tuberculosis reported from Latin America and consists of 4,411,530 bp, including 4,251 protein-encoding genes.

Motivation The pangenome concept describes genetic variability as the union of genes shared in a set of genomes and constitutes the current paradigm for comparative analysis of bacterial populations. However, there is a lack of tools to simulate pangenome variability and structure using defined evolutionary models. Results We developed simurg, an R package that allows to simulate bacterial pangenomes using different combinations of evolutionary constraints such as gene gain, gene loss and mutation rates. Our tool allows the straightforward and reproducible simulation of bacterial pangenomes using real sequence data, providing a valuable tool for benchmarking of pangenome software or comparing evolutionary hypotheses. Availability and implementation The simurg package is released under the GPL-3 license, and is freely available for download from GitHub (https://github.com/iferres/simurg). Supplementary information Supplementary data are available at Bioinformatics online.

A major goal of phylogeographic analysis using molecular markers is to understand the ecological and historical variables that influence genetic diversity within a species. Here, we used sequences of the mitochondrial Cox1 gene and nuclear internal transcribed spacer to reconstruct its phylogeography and demographic history of the intertidal red seaweed Chondrus ocellatus over most of its geographical range in the Northwest Pacific. We found three deeply separated lineages A, B and C, which diverged from one another in the early Pliocene-late Miocene (c. 4.5-7.7 Ma). The remarkably deep divergences, both within and between lineages, appear to have resulted from ancient isolations, accelerated by random drift and limited genetic exchange between regions. The disjunct distributions of lineages A and C along the coasts of Japan may reflect divergence during isolation in scattered refugia. The distribution of lineage B, from the South China Sea to the Korean Peninsula, appears to reflect postglacial recolonizations of coastal habitats. These three lineages do not coincide with the three documented morphological formae in C. ocellatus, suggesting that additional cryptic species may exist in this taxon. Our study illustrates the interaction of environmental variability and demographic processes in producing lineage diversification in an intertidal seaweed and highlights the importance of phylogeographic approaches for discovering cryptic marine biodiversity.

Background Bovine tuberculosis (bTB) poses serious risks to animal welfare and economy, as well as to public health as a zoonosis. Its etiological agent, Mycobacterium bovis, belongs to the Mycobacterium tuberculosis complex (MTBC), a group of genetically monomorphic organisms featured by a remarkably high overall nucleotide identity (99.9%). Indeed, this characteristic is of major concern for correct typing and determination of strain-specific traits based on sequence diversity. Due to its historical economic dependence on cattle production, Uruguay is deeply affected by the prevailing incidence of Mycobacterium bovis. With the world’s highest number of cattle per human, and its intensive cattle production, Uruguay represents a particularly suited setting to evaluate genomic variability among isolates, and the diversity traits associated to this pathogen. Results We compared 186 genomes from MTBC strains isolated worldwide, and found a highly structured population in M. bovis. The analysis of 23 new M. bovis genomes, belonging to strains isolated in Uruguay evidenced three groups present in the country. Despite presenting an expected highly conserved genomic structure and sequence, these strains segregate into a clustered manner within the worldwide phylogeny. Analysis of the non-pe/ppe differential areas against a reference genome defined four main sources of variability, namely: regions of difference (RD), variable genes, duplications and novel genes. RDs and variant analysis segregated the strains into clusters that are concordant with their spoligotype identities. Due to its high homoplasy rate, spoligotyping failed to reflect the true genomic diversity among worldwide representative strains, however, it remains a good indicator for closely related populations. Conclusions This study introduces a comprehensive population structure analysis of worldwide M. bovis isolates. The incorporation and analysis of 23 novel Uruguayan M. bovis genomes, sheds light onto the genomic diversity of this pathogen, evidencing the existence of greater genetic variability among strains than previously contemplated. Electronic supplementary material The online version of this article (10.1186/s12864-017-4249-6) contains supplementary material, which is available to authorized users.

The Cry1F protein from Bacillus thuringiensis Berliner expressed in event TC1507 maize (Zea mays L.) was one of the most effective ways to control Spodoptera frugiperda (J. E. Smith) in Brazil. After reports of reduced effectiveness of this Bt maize event in some areas of Brazil, research was undertaken to investigate if damage to Cry1F maize was caused by resistant S. frugiperda. Additional investigations were conducted to evaluate the genetic basis of the resistance and to test if Cry1F resistant S. frugiperda selected from populations of different regions of Brazil share the same resistance locus by using complementation tests. Neonate larvae of S. frugiperda collected from TC1507 maize fields with damage in Western Bahia region in 2011 were able to survive on Cry1F maize plants under laboratory conditions and subsequently produced normal adults. Survival of Cry1F-susceptible S. frugiperda on non-Bt maize was significantly higher in leaf than plant bioassays. Resistance ratio in diet overlay bioassays was >5000-fold. A discriminating concentration of 2000 ng cm−2 of Cry1F protein was defined for monitoring the frequency of resistance of S. frugiperda to Cry1F. Cry1F resistant S. frugiperda showed a recessive autosomal inheritance for alleles involved in resistance to Cry1F protein. In complementation tests, the resistant population from Western Bahia was crossed with the other seven resistant populations collected from different States of Brazil. F1 larvae from each cross had the same survival at discriminating concentration of 2000 ng cm−2 of Cry1F protein, indicating that the resistance alleles in each population were likely at the same locus. Therefore, implementation of resistance management strategies is urgent to prolong the lifetime of Cry1F for controlling S. frugiperda in Brazil.

Cochliomyia hominivorax (Coquerel) is a myiasis fly that causes economic losses to livestock farmers in warmer American regions. Previous studies of this pest had found population structure at north and south of the Amazon Basin, which was considered to be a barrier to dispersal. The present study analyzed three mitochondrial DNA (mtDNA) markers and eight nuclear microsatellite loci to investigate for the first time the genetic diversity and population structure across the Brazilian Amazon region (Amazonia). Both mtDNA and microsatellite data supported the existence of much diversity and significant population structure among nine regional populations of C. hominivorax, which was found to be surprisingly common in Amazonia. Forty-six mtDNA haplotypes were identified, of which 39 were novel and seven had previously been found only at south of Amazonia. Seventy microsatellite alleles were identified by size, moderate to high values of heterozygosity were discovered in all regions, and a Bayesian clustering analysis identified four genetic groups that were not geographically distributed. Reproductive compatibility was also investigated by laboratory crossing, but no evidence of hybrid dysgenesis was found between an Amazonian colony and one each of from Northeast and Southeast Brazil. The results have important implications for area-wide control by the Sterile Insect Technique.

Intra- and inter-population genetic variability and the demographic history ofHeliothis virescens(F.) populations were evaluated by using mtDNA markers (coxI, coxIIandnad6) with samples from the major cotton- and soybean-producing regions in Brazil in the growing seasons 2007/08, 2008/09 and 2009/10. AMOVA indicated low and non-significant genetic structure, regardless of geographical scale, growing season or crop, with most of genetic variation occurring within populations. Clustering analyzes also indicated low genetic differentiation. The haplotype network obtained with combined datasets resulted in 35 haplotypes, with 28 exclusive occurrences, four of them sampled only from soybean fields. The minimum spanning network showed star-shaped structures typical of populations that underwent a recent demographic expansion. The recent expansion was supported by other demographic analyzes, such as the Bayesian skyline plot, the unimodal distribution of paired differences among mitochondrial sequences, and negative and significant values of neutrality tests for the Tajima'sDand Fu'sFSparameters. In addition, high values of haplotype diversity (Ĥ) and low values of nucleotide diversity (π), combined with a high number of low frequency haplotypes and values of θπW, suggested a recent demographic expansion ofH. virescenspopulations in Brazil. This demographic event could be responsible for the low genetic structure currently found; however, haplotypes present uniquely at the same geographic regions and from one specific host plant suggest an initial differentiation amongH. virescenspopulations within Brazil.

The phylogeographical history of the pest fly screwworm, Cochliomyia hominivorax (Coquerel), was studied using partial mitochondrial DNA sequences of the control region, Cytochrome c oxidase (CO) subunit I and CO subunit II from 361 individuals collected across its current geographic range. Analyses showed marked genetic differentiation on a macrogeographic scale. The genetic diversity in the species is structured into four main "regional groups," corresponding to Cuba, the Dominican Republic, and the North and South Amazon region. Results indicated that the distribution of screwworm genetic diversity was mainly shaped by historical events, i.e., colonization of Caribbean islands, vicariance in the Amazon region and population expansion. Demographic history analyses revealed that the population expansion started approximately 20-25,000 yr ago and recently increased exponentially. We hypothesized that the initial period of expansion was probably associated with environmental amelioration in the late Pleistocene and the exponential increase with resource availability in recent times. The population expansion is probably responsible for the low divergence and the lack of genetic and geographic correlation in the South Amazon region but did not erase the genetic structure pattern on a continental scale. The screwworm is one of the most damaging livestock pests in South and Central America, and the pattern of genetic variability distribution reported here suggests that the Caribbean area and the North and South Amazon regions could be considered as independent units for future pest control programs.

Background The evolution of insecticide resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae) has resulted in large economic losses and disturbances to the environment and agroecosystems. Resistance to lufenuron, a chitin biosynthesis inhibitor insecticide, was recently documented in Brazilian populations of S. frugiperda. Thus, we utilized large-scale cDNA sequencing (RNA-Seq analysis) to compare the pattern of gene expression between lufenuron-resistant (LUF-R) and susceptible (LUF-S) S. larvae in an attempt to identify the molecular basis behind the resistance mechanism(s) of S. frugiperda to this insecticide. Results A transcriptome was assembled using approximately 19.6 million 100 bp-long single-end reads, which generated 18,506 transcripts with a N50 of 996 bp. A search against the NCBI non-redundant database generated 51.1 % (9,457) functionally annotated transcripts. A large portion of the alignments were homologous to insects, with the majority (45 %) being similar to sequences of Bombyx mori (Lepidoptera: Bombycidae). Moreover, 10 % of the alignments were similar to sequences of various species of Spodoptera (Lepidoptera: Noctuidae), with 3 % of them being similar to sequences of S. frugiperda. A comparative analysis of the gene expression between LUF-R and LUF-S S. frugiperda larvae identified 940 differentially expressed transcripts (p ≤ 0.05, t-test; fold change ≥ 4). Six of them were associated with cuticle metabolism. Of those, four were overexpressed in LUF-R larvae. The machinery involved with the detoxification process was represented by 35 differentially expressed transcripts; 24 of them belonging to P450 monooxygenases, four to glutathione-S-transferases, six to carboxylases and one to sulfotransferases. RNA-Seq analysis was validated for a number of selected candidate transcripts by using quantitative real time PCR (qPCR). Conclusions The gene expression profile of LUF-R larvae of S. frugiperda differs from LUF-S larvae. In general, gene expression is much higher in resistant larvae when compared to the susceptible ones, particularly for those genes involved with pathways for xenobiotic detoxification, mainly represented by P450 monooxygenases transcripts. Our data indicate that enzymes involved with the detoxification process, and mostly the P450, are one of the resistance mechanisms employed by the LUF-R S. frugiperda larvae against lufenuron. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2183-z) contains supplementary material, which is available to authorized users.

Livestock production is an important economic activity in Brazil, which has been suffering significant losses due to the impact of parasites. The New World screwworm (NWS) fly, Cochliomyia hominivorax, is an ectoparasite and one of the most important myiasis-causing flies endemic to the Americas. The geographic distribution of NWS has been reduced after the implementation of the Sterile Insect Technique (SIT), being eradicated in North America and part of Central America. In South America, C. hominivorax is controlled by chemical insecticides, although indiscriminate use can cause selection of resistant individuals. Previous studies have associated the Gly137Asp and Trp251Leu mutations in the active site of carboxylesterase E3 to resistance of diethyl and dimethyl-organophosphates insecticides, respectively. Here, we have sequenced a fragment of the carboxylesterase E3 gene (ChαE7), comprising part of intron iII, exon eIII, intron iIII and part of exon eIV, and three mitochondrial gene sequences (CR, COI and COII), of NWS flies from 21 locations in South America. These markers were used for population structure analyses and the ChαE7 gene was also investigated to gain insight into the selective pressures that have shaped its evolution. Analysis of molecular variance (AMOVA) and pairwise FST analysis indicated an increased genetic structure between locations in the ChαE7 compared to the concatenated mitochondrial genes. Discriminant analysis of principal components (DAPC) and spatial analysis of molecular variance (SAMOVA) indicated different degrees of genetic structure for all markers, in agreement with the AMOVA results, but with low correlation to geographic data. The NWS fly is considered a panmitic species based on mitochondrial data, while it is structured into three groups considering the ChαE7 gene. A negative association between the two mutations related to organophosphate resistance and Fay & Wu’s H significant negative values for the exons, suggest that these mutations evolved under positive selection.

Background Helicobacter valdiviensis is a recently described enterohepatic species isolated from wild bird's fecal samples. Currently, its pathogenic potential and clinical significance are unknown mainly due to the lack of whole-genome sequences to compare with other helicobacters and the absence of specific screenings to determine its prevalence in humans. Materials and Methods The species type strain (WBE14T) was whole-genome-sequenced, and comparative analyses were carried out including the genomes from other Helicobacter species to determine the exact phylogenetic position of H. valdiviensis and to study the presence and evolution of virulence determinants. In parallel, stools from diarrheic patients and healthy individuals were screened by PCR to assess the clinical incidence of H. valdiviensis. Results Helicobacter valdiviensis belongs to a monophyletic clade conformed by H. canadensis, H. pullorum, H. winghamensis, H. rodentium, and H. apodemus. Its predicted genome size is 2 176 246 bp., with 30% of G+C content and 2064 annotated protein-coding genes. The patterns of virulence factors in H. valdiviensis were similar to other enterohepatic species, but evidence of horizontal gene transfer from Campylobacter species was detected for key genes like those coding for the CDT subunits. Positive PCR results confirmed the presence of H. valdiviensis in 2 of 254 (0.78%) stools of patients with acute diarrhea while not a single sample was positive in healthy individuals. Conclusions Horizontal gene transfer has contributed to shape the gene repertory of H. valdiviensis, which codes for virulence factors conserved in other pathogens that are well-known human pathogens. Additionally, the detection of H. valdiviensisDNA in diarrheic patients supports its role as a potential emergent intestinal pathogen. Further, sampling efforts are needed to uncover the clinical relevance of this species, which should be accomplished by the isolation of H. valdiviensis from ill humans and the obtention of whole genomes from clinical isolates.

The Asian citrus psyllid Diaphorina citri is currently the major threat to the citrus industry as it is the vector of Candidatus Liberibacter, the causal agent of huanglongbing disease (HLB). D. citri is native to Asia and now colonizes the Americas. Although it has been known in some countries for a long time, invasion routes remain undetermined. There are no efficient control methods for the HLB despite the intensive management tools currently in use. We investigated the genetic variability and structure of populations of D. citri to aid in the decision making processes toward sustainable management of this species/disease. We employed different methods to quantify and compare the genetic diversity and structure of D. citri populations among 36 localities in Brazil, using an almost complete sequence of the cytochrome oxidase I (COI) gene. Our analyses led to the identification of two geographically and genetically structured groups. The indices of molecular diversity pointed to a recent population expansion, and we discuss the role of multiple invasion events in this scenario. We also argue that such genetic diversity and population structure may have implications for the best management strategies to be adopted for controlling this psyllid and/or the disease it vectors in Brazil.

The myiasis causing New World screwworm (NWS) fly is responsible for substantial losses to livestock breeders in the Americas. Due to the negative impact of the NWS fly in animal health, expansion of successful NWS fly eradication programmes is under discussion. However, the effects of geography and environmental diversity on NWS population structure and migration patterns need to be assessed before any political decision is made to implement such a programme. We present a GIS tool to construct potential connection corridors among sampling localities based on genetic and environmental data. We integrate, through a home-made python script, a friction raster based on a Maxent niche model and the pairwise ΦST statistic. Among 38 NWS fly sampling localities from South America, we find a high population connectivity among the sampling localities from the south of the Amazon region. The region along the Atlantic Ocean was identified as the most probable migration corridor between the north (NAG) and the south (SAG) of the Amazon region. The approach highlighted previously undetected population structure within NAG showing low to medium connectivity through the Andes, correlating with current understanding of NWS fly migration in South America. Also, the approach is flexible, allowing future research to incorporate other niche simulations and genetic differentiation metrics. With this flexibility, the tool could become part of any AW-IPM by helping to target regions for control.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:30:49Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:48:59Z : No. of bitstreams: 1 2-s2.0-84884834518.pdf: 973269 bytes, checksum: aa81bce63663f9d68c55e508f5e279aa (MD5) Made available in DSpace on 2014-05-27T11:30:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-10-02 Insect pest phylogeography might be shaped both by biogeographic events and by human influence. Here, we conducted an approximate Bayesian computation (ABC) analysis to investigate the phylogeography of the New World screwworm fly, Cochliomyia hominivorax, with the aim of understanding its population history and its order and time of divergence. Our ABC analysis supports that populations spread from North to South in the Americas, in at least two different moments. The first split occurred between the North/Central American and South American populations in the end of the Last Glacial Maximum (15,300-19,000 YBP). The second split occurred between the North and South Amazonian populations in the transition between the Pleistocene and the Holocene eras (9,100-11,000 YBP). The species also experienced population expansion. Phylogenetic analysis likewise suggests this north to south colonization and Maxent models suggest an increase in the number of suitable areas in South America from the past to present. We found that the phylogeographic patterns observed in C. hominivorax cannot be explained only by climatic oscillations and can be connected to host population histories. Interestingly we found these patterns are very coincident with general patterns of ancient human movements in the Americas, suggesting that humans might have played a crucial role in shaping the distribution and population structure of this insect pest. This work presents the first hypothesis test regarding the processes that shaped the current phylogeographic structure of C. hominivorax and represents an alternate perspective on investigating the problem of insect pests. © 2013 Fresia et al. Departamento de Entomologia e Acarologia Escola Superior de Agricultura 'Luiz de Queiroz' Universidade de São Paulo, São Paulo Centro de Biologia Molecular e Engenharia Genética Instituto de Biologia Universidade Estadual de Campinas, São Paulo Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista, São Paulo Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista, São Paulo

The New World screwworm Cochliomyia hominivorax (Coquerel) is an important parasitic insect pest in Neotropical regions. New World screwworm myiasis is caused by the larval stage of the fly infesting tissues of warm-blooded vertebrates. This species represents a serious threat to the livestock sector across its current distribution, which includes part of the Caribbean and all of South America (except for Chile). Knowledge of the extent and distribution of genetic variability of C. hominivorax is of great interest for the description of populations and for contributing to future strategies of control. This paper describes the analysis of genetic variability and structure of New World screwworm populations in Uruguay using two different molecular markers, mitochondrial DNA and microsatellites.

The New Word screwworm, Cochliomyia hominivorax (Coquerel 1858) (Diptera: Calliphoridae), is one of the most important insect pests of livestock in the Neotropical region. In this work, polymerase chain reaction-restriction fragment length polymorphism of mitochondrial DNA (mtDNA) was used to study the diversity and population structure of seven geographically distinct populations of C. hominivorax from most of the important livestock areas in Uruguay. The control region (A+T/12S) and subunits 1 and 2 of cytochrome oxidase (cox1/cox2) were amplified and digested with restriction endonucleases. Nine haplotypes were observed among the populations sampled. The mean nucleotide diversity and the haplotype diversity indicated high mtDNA variability in this species. The similarity index, average nucleotide divergence, and analysis of molecular variance results showed no evidence of subpopulation differentiation, indicating that the C. hominivorax populations of Uruguay form a single panmitic population. The distribution pattern of the genetic variation in natural populations of C. hominivorax and the implications of these results for establishing control program are discussed.