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In the last two decades, the increase in population genetics studies has contributed to elucidating important questions about the evolution of the pathogenesis of bacteria of clinical interest. The objective of this study is to revise and update the knowledge of the last fifteen years regarding the genetic variability of Streptococcus mutans and their association with dental caries. Streptococcus mutans, one of the most widely distributed bacteria in the world, are heavily associated with this condition. This research shows the results of numerous studies carried out in various countries that, using molecular and biochemical methods, revealed associations between different serotypes and caries activity. In addition, it is reported that the population genetics structure of Streptococcus mutans in Argentina is highly recombinant, which reflects the largest waves of human immigration that occurred in the 19th and 20th centuries. On the other hand, demographic analysis suggests that these bacteria experienced a population expansion that coincided with the beginning of agricultural development.

The Yungas, a subtropical mountain rainforest of South America, has been little studied in relation to the evolutionary history of the large-bodied species of the genus Calomys. Particularly, two species have been synonymized: C. boliviae and C. fecundus; the first is only known from its type locality in the northern Bolivian Yungas, whereas the second is known along the Tucumane–Bolivian Yungas shared by Bolivia and Argentina. In this study, we combined a phylogeographic approach with ecological niche modeling, with samples covering most of the geographic range of C. fecundus. One mitochondrial and two nuclear genes were used for population genetic analyses. Current and paleoclimatic models were obtained. Nuclear genes resulted uninformative by retention of ancestral polymorphism with other species of Calomys. The mitochondrial marker revealed a complex network showing signals of several population expansions. Three genetic clusters in a latitudinal sense were detected, which are coincident with the three stable climatic zones estimated by current and paleoclimatic models. We determined a pattern of expansion during glacial cycles and ancestral refugia during interglacial cycles. None of the potential distribution models predicted the presence of C. fecundus in the type locality of C. boliviae. Therefore, we recommend making integrative taxonomic studies in the Bolivian Yungas, to determine whether or not C. fecundus and C. boliviae correspond to the same species. Fil: Pinotti, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Ferreiro, Alejandro Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Martin, Maria Laura. Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui; Argentina Fil: Levis, Silvana del Carmen. Instituto Nacional de Enfermedades Virales Humanas Dr. Julio I. Maiztegui; Argentina Fil: Chiappero, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Cátedra de Genética de Poblaciones y Evolución; Argentina Fil: Andreo, Verónica Carolina. Instituto Nacional de Medicina Tropical; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina. Universidad Nacional de Córdoba. Facultad de Cs.exactas Físicas y Naturales. Cátedra de Genética de Poblaciones y Evolución; Argentina

The scallop Argopecten purpuratus is a heavily exploited resource along the coasts of Peru and north-central Chile, especially after El Niño events, when the species undergoes high increases in abundance. Little is known about its genetic structure or demographic history, two important factors to ensure sustainable exploitation. We sequenced the cytochrome oxidase I and cytochrome b genes of 116 individuals from six localities (between 05°44′S 80°53′W and 23°31′S 70°33′W). We found high levels of genetic diversity in the analyzed populations. No geographical structuring was observed in the haplotype network, which consisted of a few central, widely distributed haplotypes, and many derived population-specific haplotypes separated by few mutations. This pattern suggests a recent population expansion and moderate to low current gene flow among populations. Mismatch analysis, neutrality tests, and a Bayesian skyline analysis confirmed the occurrence of a past event of population expansion approximately 5,000 years ago, which coincides with increasingly stronger and more frequent El Niño events. Fil: Acosta Jofré, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Sahade, Ricardo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Mendo, Jaime. Universidad Nacional Agraria La Molina ; Perú Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Laudien, Jürgen. Alfred-Wegener-Institut. Helmholtz-Zentrum für Polar und Meeresforschung; Alemania Fil: Chiappero, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

The nominal species Oligoryzomys flavescens (yellow pygmy rice rat) appears in different phylogenetic reconstructions as paraphyletic, forming a complex together with Oligoryzomys fornesi (Fornes' pygmy rice rat) or Oligoryzomys sp. B. To test if O. flavescens includes cryptic species, we used a phylogenetic and a phylogeographic approach to analyze the evolutionary relationships among the lineages of this complex and estimated their geographical distributions using niche modeling analysis. We analyzed a portion of the mitochondrial cytochrome b (Cytb), exon 1 of the Interphotoreceptor Retinoid Binding Protein (Rhp3), and intron 7 of the beta fibrinogen (Fgb) genes and estimated divergence times among lineages using a fossil-calibrated molecular clock. The Cytb phylogenetic tree shows 2 main clades: 1 clustering individuals distributed predominantly in the east of the study area and the other grouping individuals from the west, which would correspond to the subspecies O. f. occidentalis. The eastern clade includes 5 lineages: Oligoryzomys sp. B, O. fornesi, and 3 clades named O. flavescens (O. flavescens Uruguay and southeastern Brazil, O. flavescens eastern Brazil, and O. f. flavescens). The phylogenetic break between these 2 main clades occurred about 0.89 million years ago. These clades were not recovered when nuclear markers were evaluated, revealing incomplete lineage sorting and retention of ancestral polymorphisms. The spatial distributions of the ecological niche of the clades obtained in the Cytb phylogenetic reconstructions were predominantly parapatric; narrow overlapping zones between some of them were detected. Phylogeographic analyses in O. f. flavescens revealed a population expansion about 100,000 years ago, and conformed to an isolation by distance pattern. Our results, together with morphological differences previously described between populations belonging to the east and the samples referable to O. f. occidentalis, suggest that the latter should be recognized as a full species. Fil: Rivera, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Robainas Barcia, Aymée. Pierre Fabre Iberica; España Fil: Trimarchi, Laura Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Levis, Silvana. Instituto Nacional de Enfermedades Virales Humanas Dr Julio I. Maiztegui; Argentina Fil: Calderon, Gladys. Instituto Nacional de Enfermedades Virales Humanas Dr Julio I. Maiztegui; Argentina Fil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

The population genetic structure of Oligoryzomys longicaudatus colilargo was examined at two geographical scales: (a) regional, including five populations of the Argentinean Patagonia separated by 60–315 km and (b) landscape scale, using five populations from different valleys of the locality of Cholila in the subantarctic forest separated by 6–27 km, and a nearby locality of the Patagonian steppe, with an average distance from Cholila of 33 km. Eight microsatellite loci specific for O. longicaudatus were used as genetic markers. At the regional scale, four genetic clusters were detected by the Geneland software. The genetic structure was found to follow a latitudinal pattern. This result was supported by the FST statistic, indicating low levels of current gene flow within the region. At the landscape level, genetic differentiation among the five populations was also found. Estimated migration rates were, in general, low and asymmetrical between nearby populations. Using a causal modeling approach, we detected that the combination of landscape features such as lakes, rivers, urban settlements and roads appear to constrain the dispersal of O. longicaudatus at this scale. This result would explain why nearby populations were so different in their genetic composition. The information about geographic features limiting rodent dispersal provided here could help to design more accurate prevention measures against the expansion of hantavirus pulmonary syndrome. Fil: Ortiz, N.. Universidad Nacional de Córdoba; Argentina Fil: Polop, Francisco Jose. Universidad Nacional de Río Cuarto; Argentina Fil: Andreo, Verónica Carolina. Universidad Nacional de Río Cuarto; Argentina Fil: Provensal, María Cecilia. Universidad Nacional de Río Cuarto; Argentina Fil: Polop, Jaime Jose. Universidad Nacional de Río Cuarto; Argentina Fil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

The long-tailed pygmy rice rat Oligoryzomys longicaudatus (Rodentia, Cricetidae) experiences marked population density fluctuations. This species is the major reservoir of the Andes orthohantavirus associated with the hantavirus pulmonary syndrome in southern Argentina, and information on dispersal patterns at different population densities, or differences in dispersal between the sexes during those periods, could contribute to understanding risk of viral transmission among individuals. We examined the spatial genetic structure of O. longicaudatus at a local scale to elucidate how variation in population density influences dispersal patterns. Effective dispersal levels were estimated through spatial genetic autocorrelation (SGA) analyses in periods of different density, and for females and males separately, within an area of 510 × 180 m, using seven microsatellite loci. In autumn (high-intermediate and intermediate densities), SGA was primarily determined by females, which show philopatric behavior in defense of their nests and newborns. In summer (low density), neither sex showed SGA, which could be due to spacing behavior combined with high recruitment rates among adjacent environments. At high-intermediate densities, females remained close to each other, contracting their home ranges. These established individuals would “fence” the area, preventing the immigration of individuals from proximate areas, until population density declines again. We detected differential patterns of effective dispersal for both sexes in different stages of the annual and inter-annual population phases of O. longicaudatus. Since high levels of gene flow were reported for both sexes in summer and for males in all analyzed seasons, the transmission risk of diseases such as hantavirus pulmonary syndrome would be high at a local scale.La densidad poblacional del ratón “colilargo” Oligoryzomys longicaudatus (Rodentia, Cricetidae) experimenta marcadas fluctuaciones. Esta especie es el principal reservorio del ortohantavirus Andes, asociado con el síndrome pulmonar por hantavirus en el sur de Argentina. El conocimiento sobre los patrones de dispersión a diferentes densidades poblacionales y entre los sexos durante esos períodos, podría contribuir a evaluar el riesgo de transmisión viral entre individuos. Examinamos la estructura genética espacial de O. longicaudatus a escala local para determinar de qué manera las variaciones en la densidad poblacional influyen sobre los patrones de dispersión del roedor. Los niveles de dispersión efectiva se estimaron mediante análisis de autocorrelación genética espacial (AGE) utilizando siete loci de microsatélites, dentro de un área de 510 × 180 m. Los análisis se hicieron en distintos períodos de densidad para la población general y para hembras y machos por separado. En otoño (densidad alta-intermedia e intermedia), la AGE estuvo determinada principalmente por las hembras, lo que podría explicarse por su comportamiento filopátrico en relación a la defensa de sus nidos y crías. En verano (baja densidad), ninguno de los sexos mostró AGE, debido a un comportamiento de espaciamiento combinado con altas tasas de reclutamiento entre ambientes adyacentes con diferentes recursos. A densidades altas-intermedias, las hembras permanecieron cerca una de la otra, contrayendo su área de acción. Estos individuos cercarían el área, evitando la inmigración de individuos de áreas cercanas, hasta que la densidad poblacional disminuya nuevamente. Detectamos patrones diferenciales de dispersión efectiva para ambos sexos en cada una de las fases de densidad poblacional (anual e interanual) de O. longicaudatus. El riesgo de transmisión del síndrome pulmonar por hantavirus sería elevado a escala local, dado que se detectaron altos niveles de flujo génico para ambos sexos en verano y para los machos en todas las estaciones analizadas.

In the present study, we analysed the genetic structure of Triatoma infestans populations with a phylogeographical approach using sequences of the mitochondrial NADH dehydrogenase subunit 5 (ND5) and the nuclear elongation factor-1 alpha (EF-1α) genes of bugs obtained from Argentina and Bolivia. Spatially circumscribed haplogroups were distinguished from the ND5 gene sequences, one distributed exclusively to the south of the studied area and, in agreement with the results from the EF-1α gene, one haplogroup limited to Bolivia and another to Morajú located in the Chaco region of Argentina. In both the ND5 and EF-1α networks, the most widespread haplogroup or allele group showed a star-like topology, which is compatible with a recent demographic expansion. The asymmetric historical gene flow detected from a population of the Chaco region towards Bolivia and the spatiotemporal phylogeographical reconstruction of lineage dispersal would support the hypothesis that postulates the Chaco biogeographical region as the area of origin for the species. However, additional studies with a broader sampling in the Andean region are needed to define with certainty whether the origin of T. infestans is Chacoan or Andean.

Despite of the substantial economic and human health problems produced by rodents of the genus Rattus almost nothing is known about its actual dispersal. In the present study we analyze the genetic subdivision of R. norvegicus inhabiting poultry farms of Buenos Aires, Argentina, and the relation between geographic and genetic distances by means of variation in microsatellite loci. We genotyped 40 rats captured between April-06 and June-07 from nine poultry farms distributed in an area of 110 km2 . No genetic subdivision was found among di erent poultry farms. This result supports the hypothesis of high connectivity between R. norvegicus inhabiting poultry farms in Buenos Aires. Because this species is a known host of diverse zoonosis as leptospirosis and trichinosis, our results point out that there is a great risk of transmission for distances lower than 12 km. Health control and preventive measures should therefore be applied simultaneously in all nearby poultry farms. A pesar de los problemas económicos y de salud producidos por roedores del género Rattus, se conoce muy poco sobre su dispersión efectiva. En el presente estudio analizamos la subdivisión genética de las subpoblaciones de R. norvegicus que habitan granjas avícolas de Buenos Aires, Argentina, y la relación entre las distancias geográ cas y genéticas por medio de la variabilidad en loci de microsatélites. Se genotiparon 40 ratas capturadas entre abril-06 y junio-07 en nueve granjas avícolas distribuidas dentro de un área de 110 km2 . No se encontró subdivisión genética entre las diferentes granjas avícolas. Esto apoya la hipótesis de alta conectividad entre R. norvegicus que habitan granjas avícolas en Buenos Aires. Debido a que R. norvegicus es un conocido hospedador de diversas zoonosis como leptospirosis y triquinosis, nuestros resultados indican que existe un gran riesgo de transmisión para distancias menores a 12 km. La medidas de control y prevención sanitarias deberían, por lo tanto, aplicarse en todas las granjas cercanas en forma simultánea. Fil: Gomez Villafañe, Isabel Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Guzman, Noelia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Ortiz, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Fisiología. Cátedra de Genética de Poblaciones y Evolución; Argentina Fil: Leon, Vanina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Busch, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

The nominal species Calomys tener (Winge, 1887) ranges broadly in open lands of the Caatinga, Cerrado, Pantanal and Mata Atlântica of Brazil, and was recently reported from the Pampas of southern Brazil, and in the Selva Paranaense of eastern Paraguay and northeastern Argentina. This rodent can be infected with the pathogenic Araraquara hantavirus in Brazil. Given that most epidemiological studies have not taken into account updated taxonomic findings of their rodent hosts, in this study, we obtained sequence data of the Cyt-b and COI genes of specimens of C. tener from 22 different geographical localities from throughout the currently known distribution of the species (including individuals from Argentina, Paraguay, Bolivia, and Brazil) to test if it constitutes a single genetic unit or if it presents genetic discontinuities that may represent different evolutionary lineages. Phylogenetic analyses including several species of Calomys recovered several clades with strong support. Regarding C. tener, it is recovered as sister to the node that cluster C. laucha (Fischer, 1814) sensu lato, C. expulsus (Lund, 1841) and species in the C. callosus (Rengger, 1830) species complex. At the intraspecific level there are no genetic gaps among haplotypes of C. tener that could suggest more than one species. The recent captures in the Pampas of southern Brazil and in the Selva Paranaense suggest that the species may be colonizing new geographic areas. Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Kandel, Narayan P.. Texas Tech University. Department Of Biological Sciences; Estados Unidos Fil: Bonvicino, Cibele R.. Instituto Nacional de Cáncer. División de Genetica; Brasil Fil: Salazar-Bravo, Jorge. Texas Tech University. Department Of Biological Sciences; Estados Unidos

To identify and predict situations of increased risk of orthohantavirus infection in humans, it is necessary to study the relationships between the virus and its rodent hosts. The present study investigated orthohantavirus infection in an assemblage of wild Sigmodontinae rodents of the Paraná Delta, Argentina, and providing new evidence of host-switching events. Rodents belonging to the species Oxymycterus rufus (n=187), Akodon azarae (n=82), Oligoryzomys flavescens (n=80), Oligoryzomys nigripes (n=47), Scapteromys aquaticus (n=38), Deltamys kempi (n=7) and Holochilus brasiliensis (n=2) were captured at 4 sampling sites during 20 trapping sessions. Blood sampleswere analyzed by IgG ELISA and livers by a nested reverse transcription PCR for the diagnosis of orthohantavirus infection. The amplified products of the S and M orthohantavirus genomes were sequenced and analyzed to determine similarities with species of the Orthohantavirus genus. The species of the Oligoryzomys positive to the virus were confirmed by amplifying and sequencing thecomplete cyt b gene. Of the 443 serum samples analyzed by IgG ELISA, A. azarae presented the highest host-specific prevalence value (10/82, 12.2%) followed by Ol. nigripes (4/47, 8.5 %) and Ox. rufus (1/187, 0.5%). All the sero-positive Ol. nigripes (n= 4) were positive to the amplification of the S and M segments of the Lechiguanas genotype (98% nucleotide identity for both segments).This is surprising given that Ol. nigripes has been previously associated with Juquitiba genotype, not Lechiguanas. The latter is generally associated with Ol. flavescens, which in our study were all sero-negative. In addition, the association Ox. rufus ? Pergamino genotype found here is, to ourknowledge, novel and another potential evidence of host-switching considering that Pergamino has been originally associated with A. azarae. These findings contribute to the building evidence that contradicts the one-genotype-one-reservoir species premise in the association betweenrodent reservoirs and orthohantaviruses, and supports the hypothesis that the community structure of sympatric host species may contribute to orthohantavirus dynamics. Fil: Colombo, Valeria Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina Fil: Brignone, Juan Jeronimo. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Sen, Carina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Previtali, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Martin, María Laura. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Levis, Silvana del Carmen. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina Fil: Monje, Lucas Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina Fil: González Ittig, Raúl Enrique. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; Argentina Fil: Beldomenico, Pablo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; Argentina

The population genetics of Triatoma dimidiata haplogroups was analyzed at landscape and sub-regional scales in Chiapas and regional level across the Mexican Neotropics, and phylogeography of the complex was re-analyzed across its complete geographic range. Two contiguous fragments of the ND4 gene were analyzed due to bias from differential haplogroup specificity using a previously designed sequence. At both landscape (anthropic modification gradient) and regional (demographic, fragmentation, biogeographic, climate) scales, lowest T. dimidiata genetic diversity occurs where there is greatest historical anthropic modification, and where T. cruzi infection prevalence is significantly highest. Trypanosoma cruzi prevalence was significantly higher than expected in haplogroups 1 and 3, while lower than expected in haplogroup 2. There was also a significant difference of DTUI and DTUVI infection frequencies in both haplogroups 1 and 3, while no difference of either in haplogroup 2. All haplogroups from the Mexican Neotropics had moderate to high haplotype diversity, while greatest genetic differentiation was between haplogroups 1 and 3 (above FST = 0.868, p < 0.0001). Divergence of the complex from the MRCA was estimated between 0.97 MYA (95% HPD interval = 0.55–1.53 MYA) and 0.85 MYA (95% HPD interval = 0.42–1.5 MYA) for ND4A and both concatenated fragments, respectively, with primary divergence from the MRCA of haplogroups 2 and 3. Effective population size for Mexican haplogroups 1 and 2 increased between 0.02 and 0.03 MYA. This study supports previous ecological niche evidence for the complex´s origin surrounding the Tehuantepec Isthmus, and provides evidence for recent divergence of three primary dimidiata haplogroups, with differential T. cruzi infection frequency and DTU specificity, important components of vector capacity., Author summary Triatoma dimidiata is one of the broadest distributed triatomine species´ complexes transmitting Trypanosoma cruzi. In Mexico, three haplogroups of the T. dimidiata complex have been reported and all are primary vectors of Chagas disease south of the Tehuantepec Isthmus. Given their epidemiological importance, the question arises whether haplogroups have similar genetic diversity in domestic/modified landscapes, as well as infection characteristics and parasite DTU associations, key components of vector capacity. The aim of the present study was to analyze Triatoma dimidiata population genetics across landscapes, sub-regional, regional, and global Neotropical realm scales, using two contiguous fragments of the ND4 gene. Our results support previous evidence for the complex´s origin surrounding the Tehuantepec Isthmus, and provides evidence for recent divergence of three principal dimidiata haplogroups and significant secondary divergence within each. Differential T. cruzi prevalence and Discrete Typing Unit (DTU) specificity for individual haplogroups provide evidence for potential differential vector capacity within the complex in Mexico.

Background The Lutzomyia longipalpis complex has a wide but discontinuous distribution in Latin America, extending throughout the Neotropical realm between Mexico and northern Argentina and Uruguay. In the Americas, this sandfly is the main vector of Leishmania infantum, the parasite responsible for Visceral Leishmaniasis (VL). The Lu. longipalpis complex consists of at least four sibling species, however, there is no current consensus on the number of haplogroups, or on their divergence. Particularly in Argentina, there have been few genetic analyses of Lu. longipalpis, despite its southern expansion and recent colonization of urban environments. The aim of this study was to analyze the genetic diversity and structure of Lu. longipalpis from Argentina, and to integrate these data to re-evaluate the phylogeography of the Lu. longipalpis complex using mitochondrial markers at a Latin American scale. Methodology/Principal findings Genetic diversity was estimated from six sites in Argentina, using a fragment of the ND4 and the 3´ extreme of the cyt b genes. Greatest genetic diversity was found in Tartagal, Santo Tomé and San Ignacio. There was high genetic differentiation of Lu. longipalpis in Argentina using both markers: ND4 (FST = 0.452, p < 0.0001), cyt b (FST = 0.201, p < 0.0001). Genetic and spatial Geneland analyses reveal the existence of two primary genetic clusters in Argentina, cluster 1: Tartagal, Santo Tomé, and San Ignacio; cluster 2: Puerto Iguazú, Clorinda, and Corrientes city. Phylogeographic analyses using ND4 and cyt b gene sequences available in GenBank from diverse geographic sites suggest greater divergence than previously reported. At least eight haplogroups (three of these identified in Argentina), each separated by multiple mutational steps using the ND4, are differentiated across the Neotropical realm. The divergence of the Lu. longipalpis complex from its most recent common ancestor (MRCA) was estimated to have occurred 0.70 MYA (95% HPD interval = 0.48–0.99 MYA). Conclusions/Significance This study provides new evidence supporting two Lu. longipalpis genetic clusters and three of the total eight haplogroups circulating in Argentina. There was a high level of phylogeographic divergence among the eight haplogroups of the Lu. longipalpis complex across the Neotropical realm. These findings suggest the need to analyze vector competence, among other parameters intrinsic to a zoonosis, according to vector haplogroup, and to consider these in the design and surveillance of vector and transmission control strategies., Author summary The Lutzomyia longipalpis complex has a wide but discontinuous distribution in Latin America, extending throughout the Neotropical realm between Mexico and northern Argentina and Uruguay. In the Americas, this sandfly is the main vector of Leishmania infantum, the parasite responsible for Visceral Leishmaniasis (VL). The Lu. longipalpis complex is composed of at least four sibling species, although there is no current consensus on the number of haplogroups, or their divergence. In Argentina, little is known about the complex population structure. Therefore, the aim of this study was to analyze the diversity and genetic structure of Lu. longipalpis from Argentina and subsequently to analyze the complex phylogeography at a Latin American scale, using two mitochondrial markers. Greatest genetic diversity was found in Tartagal, Santo Tomé and San Ignacio. Two genetic clusters and three Lu. longipalpis haplogroups were identified from the six sites in Argentina. Phylogeographic analyzes using ND4 and cyt b gene sequences and those from across the Neotropical realm registered in GenBank, suggest greater divergence than previously reported. At least eight haplogroups are differentiated using the ND4, each separated by multiple mutational steps. Lu. longipalpis complex divergence from its most recent common ancestor (MRCA) was estimated at mid Pleistocene, 0.70 MYA (95% HPD interval = 0.48–0.99 MYA).

Factors modeling the population genetic structure are of major importance when species involved in the transmission of zoonoses are considered. The long-tailed pygmy rice rat or ‘colilargo’ Oligoryzomys longicaudatus is a highly vagile rodent species which acts as the reservoir of the Andes hantavirus in southern Argentina and Chile. To contribute to the knowledge of the processes determining the microgeographical genetic structure of populations of this species, we used 10 microsatellite loci to estimate the levels of polymorphism, individual relatedness and the population effective sizes through time and to explore if the effective size correlated with density. Individuals were sampled seasonally during a 25-month period in a population from the Argentinean Patagonia located in the endemic area of Hantavirus Pulmonary Syndrome. We detected three genetic clusters. An important temporal change in cluster prevalence was detected after a population bottleneck. Individuals of the same period presented higher mean relatedness values than between consecutive periods. Density and effective population size estimations were correlated. All analyses performed in this study are in line with the conclusion that high levels of gene flow encompassing different habitats would be a major process producing fine-scale temporal changes in the genetic composition of the studied population.

Population genetic studies can contribute to current knowledge about the epidemiology of pathogens such as Streptococcus mutans, which is one of the most widely distributed bacteria in the world to be associated with human dental caries. In the present study, we investigated whether the population genetic structure of the species is clonal or recombinant, and we also evaluated the current levels of gene flow, admixed ancestry, and the hypothesis of an expansion of the bacteria within the last 10 000 years. Strains of S. mutans from Córdoba (Argentina) were obtained, with sequences of the genes aroE, gltA, gyrA, and lepC genes being aligned with those of strains from Japan, Thailand, and Finland. Most of our statistical analyses performed on the DNA matrix of 193 strains supported the existence of recombination at the intergene level. We also estimated the number of genetic clusters via Bayesian analyses, with three genetic clusters being detected in the four countries at different frequencies, as well as the number of strains with pure or admixed ancestry varying among countries. Argentina revealed 50% admixed strains, whereas these types of strains were present in only 8-19% of the other three countries analyzed. This result could be associated with the important human migration waves that Argentina has experienced, which may have mixed strains of S. mutans of different geographical origins. The demographic history was obtained using Extended Bayesian Skyline Plot anslysis, which showed important growth in the effective population size approximately 5000 years ago, coincident with the beginning of the dispersion of agriculture and a change to a diet rich in carbohydrates. Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Carletto Korber, Fabiana Pia Marina. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Biología Celular; Argentina Fil: Vera, Noelia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Jimenez, Maria Graciela. Universidad Nacional de Córdoba. Facultad de Ciencias Médicas. Hospital Universitario de Maternidad y Neonatología; Argentina Fil: Cornejo, Lila Susana. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Biología Celular; Argentina

Gonzalez-Ittig, R. E., Salazar-Bravo, J., Barquez, R. M. & Gardenal, C. N. (2010). Phylogenetic relationships among species of the genus Oligoryzomys (Rodentia, Cricetidae) from Central and South America. —Zoologica Scripta, 39, 511–526. The genus Oligoryzomys includes several species very similar in external morphology, which has resulted in a confusing specific taxonomy. Accurate species identification is particularly important because several species of Oligoryzomys act as natural hosts of hantaviruses affecting humans. Here, we assign specific status to individuals from a wide geographical area of Argentina and Chile using sequences of the mtDNA control region. We also compare cytochrome b sequences of 14 species recognized from Central and South America to infer the phylogenetic relationships within the genus. In addition, the results were analysed using available data on chromosome numbers, and the host–parasite relationships reported for the genus Hantavirus. We confirm the geographical distribution of Oligoryzomys longicaudatus (Argentina, Chile), Oligoryzomys nigripes (Argentina, Paraguay, Brazil), Oligoryzomys chacoensis (Argentina, Bolivia, Paraguay), Oligoryzomys fornesi (Argentina, Paraguay), Oligoryzomys destructor (Argentina, Bolivia) and Oligoryzomys microtis (Bolivia, Brazil). Oligoryzomys longicaudatus is strongly related to the Oligoryzomys flavescens complex, which comprises four clades; O. nigripes is closely related to Oligoryzomys stramineus, and Oligoryzomys vegetus, to Oligoryzomys fulvescens from Central America. Oligoryzomys chacoensis, O. destructor, O. fornesi, O. longicaudatus, O. microtis, O. nigripes, O. stramineus, Oligoryzomys moojeni, Oligoryzomys rupestris, O. fulvescens and O. vegetus are confirmed as valid species, whereas O. flavescens, Oligoryzomys magellanicus, Oligoryzomys griseolus, Oligoryzomys victus, Oligoryzomys andinus and Oligoryzomys arenalis need exhaustive revision. The sister species to all the remaining entities of the genus was O. microtis, suggesting an Amazonian origin for the genus.

To increase our understanding of the speciation process occurred in the sibling species Graomys griseoflavus and Graomys centralis, a phylogeographic study was conducted based on sequences of a hypervariable segment of the mtDNA D-loop region. The resulting haplotype phylogenetic network showed two well-defined clusters, one for each species. The clusters were connected by two haplotypes from localities that are almost 300 km apart, one situated in the Monte eco-region and the other, in the Chaco. This result is in agreement with a previous hypothesis about the geographical context in which the cladogenetic process occurred. A divergence time of 0.15–0.28 million years was estimated, which is consistent with a process of recent speciation. An amova test confirmed that at present gene flow between species does not exist. The mismatch distribution analyses suggest that the geographical and demographic expansion undergone by the species is related to the climatic events that occurred in the region during the Quaternary. Resumen Con el objetivo de contribuir al conocimiento del proceso de separacion de las especies Graomys griseoflavus y Graomys centralis, se realizo un estudio filogeografico basado en secuencias de un segmento de la region de D-loop del ADNmt de 39 ejemplares. La red filogenetica de haplotipos mostro dos agrupamientos bien soportados, uno para cada especie. Los grupos estan conectados por dos haplotipos presentes en localidades separadas por 300 km, una de ellas situada en la eco-region del Monte y la otra, en el Chaco. Este resultado apoya una hipotesis previa acerca del contexto geografico del proceso cladogenetico. La separacion de G. griseoflavus y G. centralis podria haber ocurrido hace 0,15–0,28 millones de anos, estimacion que concuerda con una especiacion relativamente reciente. El test de amova confirmo la ausencia de flujo genico actual entre las especies. Los analisis de distribucion de diferencias apareadas entre haplotipos sugieren expansiones geograficas y demograficas para ambas especies, probablemente relacionadas con los cambios climaticos ocurridos en la region durante el Cuaternario.

In a previous phylogeographic study of the rodent Calomys musculinus , 24 haplotypes of the mitochondrial DNA D-loop region were detected using the restriction fragment length polymorphism technique (PCR-RFLP). Seven percent of the individuals showed patterns in which the sum of the sizes of the restriction fragments exceeded the size of the original PCR product. In the present paper we analyze possible causes of these atypical haplotypes. PCR products were cloned, and two or three different clones from a single individual were detected by their RFLP patterns. Nine clones with different restriction patterns were selected for sequence analyses. A maximum parsimony phylogenetic analysis revealed two well-supported paraphyletic groups. One group comprised sequences showing low nucleotide divergence compared with the most common haplotypes detected in the phylogeographic study. The other group was basal to the three species of Calomys other than C. musculinus included in the study; the mutations in the short portion of the cytochrome b gene amplified corresponded to 12 amino acid substitutions. The results suggest that two independent insertions of mtDNA sequences into the nucleus occurred; these sequences would co-amplify in the PCR procedure. Identification of pseudogenes is crucial to obtain reliable reconstruction of the intraspecific genealogy in phylogeographic studies.

The rodent Calomys musculinus is the reservoir of the Junin virus, which causes Argentine hemorrhagic fever. A phylogeographic approach was used for the analysis of 6 populations from central Argentina based on cytochrome-b sequences from 27 individuals. Thirteen haplotypes were detected, each closely linked in the phylogenetic network; 2 of the most frequent haplotypes were internal, whereas the majority were unique to single populations and presented distal positions in the network. Most of the variance was explained by withinpopulation genetic diversity. Results of a mismatch distribution analysis and the deviation from neutrality confirmed that C. musculinus has experienced a recent range expansion; genetic drift has apparently been the main force acting at present, with low to moderate current gene flow. These results are in agreement with previous studies based on polymerase chain reaction–restriction fragment length polymorphism data of the mitochondrial D-loop region, and they support the reliability of both types of techniques.

The systematics and geographical distribution of the species of Oligoryzomys present in Argentina are poorly known. From some of the species different hantavirus genotypes have been recovered. In order to contribute to the accurate identification of those species and to infer their phylogenetic relationships, we analysed data of restriction sites and sequences of the mtDNA d-loop region. The samples used represent almost all Oligoryzomys species known to occur in Argentina. The trees obtained with the two types of data were similar, showing high bootstrap values for the majority of the nodes. Our results support the idea that the specific name Oligoryzomys longicaudatus should be applied only to individuals from the south of Argentina and Chile and confirm that O. nigripes and O. delticola are conspecific. Specimens identified as O. flavescens conform three related clades, probably belonging to a species complex. This study also emphasises that the use of a DNA fragment characterised by a high evolutionary rate compare with other mitochondrial segments as the d-loop, was appropriate to infer the phylogenetic relationships in a group originated by a rapid speciation process. We also suggest the following modifications in the rodent–hantavirus relationships: the only viral genotype associated to O. longicaudatus would be Andes Sout, while O. chacoensis would be the natural host of the genotype Oran. One of the forms of the O. flavescens complex would be the natural host of the genotype Bermejo. Our data are consistent with the hypothesis that each hantavirus genotype is associated with a specific rodent host.

In recent years, the notion of co-speciation between Hantavirus species and their hosts was discarded in favour of a more likely explanation: preferential host switching. However, the relative importance of this last process in shaping the evolutionary history of hantaviruses remains uncertain, given the present limited knowledge not only of virus–host relationships but also of the pathogen and reservoir phylogenies. In South America, more than 25 hantavirus genotypes were detected; several of them act as aetiological agents of hantavirus pulmonary syndrome (HPS). An understanding of the diversity of hantaviruses and of the processes underlying host switching is critical since human cases of HPS are almost exclusively the result of human–host interactions. In this study, we tested if preferential host switching is the main process driving hantavirus diversification in South America, by performing a co-phylogenetic analysis of the viruses and their primary hosts. We also suggest a new level of amino acid divergence to define virus species in the group. Our results indicate that preferential host switching would not be the main process driving virus diversification. The historical geographical proximity among rodent hosts emerges as an alternative hypothesis to be tested. Fil: Rivera, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

This research was aimed to analyse the genetic diversity of Geraeocormobius sylvarum, a forest-dwelling Neotropical harvestman with a disjunct distribution,separated by approximately 630 km of semi-arid environments. The usefulness of a fragment of the cytochrome c oxidase subunit I (COI) mitochondrial gene as molecular marker was tested in 109 individuals. Results showed high levels of both haplotype and nucleotide diversity in populations corresponding to north-eastern Argentina, the core area of the species range. A strong genetic structuring was detected, supported by both the phylogenetic trees and the haplotype network, with six identifiable haplogroups. Populations of the Yungas ecoregion did not show significant diversity levels, suggesting a putative recent introduction of the species into that region. The overall results suggest that the present genetic diversity of the species is consistent with past fragmentation events of the species range (in refuges?), probably during the Last Glacial Maximum. The COI gene was concluded to be a well-suited marker to associate past environmental events with the high genetic diversity observed in this species. Fil: Vaschetto, Luis Maria Benjamin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina. Universidad Nacional de Córdoba; Argentina Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina. Universidad Nacional de Córdoba; Argentina Fil: Vergara Oficialdegui, Julia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina. Universidad Nacional de Córdoba; Argentina Fil: Acosta, Luis Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentina. Universidad Nacional de Córdoba; Argentina

Subgeneric recognition of rodents of the genus Oligoryzomys from Argentina is specially difficult because morphologic and morphometric criteria to identify species are poorly defined. In order to contribute to the unequivocal identification and geographic distribution of Oligoryzomys species, we studied the restriction fragment length polymorphism (PCR-RFLP) patterns of the D-loop region of the mitochondrial DNA in specimens collected from different regions of Argentina. PCR amplification products of 59 individuals were digested with five restriction enzymes. Patterns obtained were used to produce two phylogenetic consensus trees, one obtained with PAUP and the other with MIX analyses. All specimens from the Patagonia (southern region) clustered together and would correspond to O. longicaudatus. Individuals from the North grouped in four clusters (two of them comprising one individual), supported by high bootstrap values. The one including the 82% of the rodents from the northern region would correspond to the species O. chacoensis.

Objetivo: En el presente estudio, utilizando un enfoque retrospectivo, caracterizamos la infección de VIH-1 en Córdoba (Argentina) a través de la determinación de los subtipos virales circulantes en el período 1986-2001. Métodos: Se analizaron los genes pol y env utilizando dos enfoques diferentes: 1) comparando las secuencias de Córdoba con aquellas de subtipos puros y formas recombinantes circulantes del grupo M del VIH-1; 2) subdividiendo las secuencias en matrices de subtipos puros (evitando los efectos de la recombinación) a fin de determinar si los subtipos de Córdoba tienen uno o varios orígenes geográficos. Resultados: El primer enfoque reveló que dieciocho cepas correspondían al subtipo B, siete a B/F1, una a C y una a F1. Solo dos de los B/F1 correspondían a la forma CRF12_B/F1, previamente descripta para Argentina; las secuencias B/F1 restantes serían diferentes formas de URF_B/F1. Los análisis filogenéticos del segundo enfoque sugieren que el subtipo B de Córdoba tendría múltiples orígenes geográficos, mientras que los subtipos F1 y C habrían sido introducidos directamente desde Brasil o indirectamente desde Buenos Aires. Conclusiones: La gran variabilidad de subtipos indica que la infección de VIH-1 en Córdoba fue compleja desde sus inicios. Nuestros resultados también revelan el estrecho contacto entre la gente de esta ciudad, a través del turismo y actividades comerciales, con las de Buenos Aires y Brasil.

The rodent Oligoryzomys longicaudatus or long-tailed pygmy rice rat is the reservoir of the aetiological agent of the hantavirus pulmonary syndrome in southern Argentina and Chile. We characterize 11 polymorphic microsatellite loci which would be useful for studies on microgeographical population structure in the species. Amplification of these loci in 42 individuals from four natural populations revealed four to 21 alleles per locus, and values of observed heterozygosities ranging from 0.371 to 0.896. Cross-species amplifications showed that some of the primers designed may be useful for other species of the genus Oligoryzomys.

This study's purpose was to investigate the transmission and genetic identity of Streptococcus mutans strains in mother-child pairs from Cordoba, Argentina in order to establish whether the mother was the main source of infection of the child.Seventeen mother-child pairs were analyzed, with samples taken of whole nonstimulated saliva and dental plaque when each child was 18 months old. The mothers gave their written, informed consent to participate in the study. The Streptococcus mutans strains were genotyped by the arbitrarily primed polymerase chain reaction (AP-PCR) technique using primers OPA-02, OPA-05, and OPA-13. Three statistical analyses were used to determine genetic identity (1) Dice similarity index, (2) principal coordinates analysis/minimum spanning tree (PCoA/MST) analysis, and (3) Neighbor-joining consensus tree.The AP-PCR technique showed high genetic polymorphism in the S mutans strains. According to the Dice index, 10 of the 17 pairs presented genetic identity. Results from the PCoA/MST analysis and the Neighbor-joining consensus tree showed that 7 pairs presented high similarity and the other 3 showed moderate levels of similarityAccording to the results obtained with 3 primers and with 3 different statistical methods, we could determine that the mothers are an important source of infection for the child at an early age.

The rodent Oligoryzomys longicaudatus (Bennett, 1832) (Rodentia, Cricetidae) inhabits southern forests of Argentina and Chile, a region severely affected by glaciations during the Pleistocene–Holocene periods. We evaluate here the diversity of the mitochondrial control region to characterize the genetic structure of this species from forests and bushy areas of seven populations from Argentina and four populations from Chile. Statistical analyses showed shallow haplotype trees and mismatch distributions compatible with recent range expansions. The presence of “private” haplotypes indicates that current levels of gene flow among populations of each country would be low to moderate. Significant differences in haplotype frequencies were detected between eastern and western populations, indicating that the Andes mountains would be an effective geographic barrier for gene flow despite the existing valleys that could act as corridors for dispersion. A single clade containing all the haplotypes was recovered in the phylogenetic trees, suggesting postglacial dispersion from a single refugium during the Last Glacial Maximum. The higher effective size and levels of polymorphism in populations from Chile suggest that the refugium was located in this country. The asymmetric gene flow from Chile to Argentina may reflect a recent colonization of the eastern populations.

In order to contribute to knowledge of colonization patterns in the rodent Calomys musculinus, a natural reservoir of the virus producing Argentine hemorrhagic fever (AHF), we studied the haplotype diversity of the mitochondrial DNA D-loop region in five natural populations from central Argentina. Digestion with eight restriction enzymes (RsaI, MseI, Tsp509I, AluI, AciI, HaeIII, NlaIII, and AseI) revealed polymorphism in the 1300 bp fragment amplified by PCR. Twenty different composite haplotypes were detected. Hierarchical analyses indicated that almost all variation (94%) is contained within local populations. Haplotypes 1 and 2, shared by all populations, were the most frequent. Nonsignificant genetic differentiation was found among populations of the endemic and nonendemic areas of AHF: All locations sampled presented exclusive haplotypes in spite of their geographic proximity, which would support previous observations indicating restricted gene flow among C. musculinus populations.