Genetic variation in the glucosyltransferase-B gene of Streptococcus mutans and its relationship with caries experience in children from Córdoba, Argentina, and with strains from other countries.

BACKGROUND: Caries is a worldwide distributed oral disease of multifactorial nature, with Streptococcus mutans being the most commonly isolated bacterial agent. The glycosyltransferases of this bacterium would play an essential role in the aetiology and pathogenesis of caries. AIM: We explored how the glucosyltransferase-B (gtf-B) gene variability of S. mutans from children in central Argentina correlated with their caries experience and how these strains were genetically related to those of other countries. DESIGN: Dental examinations were performed on 59 children; dmft and DMFT indexes were calculated. From stimulated saliva, S. mutans was grown and counted (CFU/mL). From bacterial DNA, the gtf-B gene was amplified and sequenced. Alleles were identified and their genealogical relationships established. Clinical, microbiological, and genetic variables were correlated with caries experience. Our sequences were included in a matrix with those from 16 countries (n = 358); genealogical relationships among alleles were obtained. Population genetic analyses were performed for countries with >20 sequences. RESULTS: The mean dmft + DMFT was 6.45. Twenty-two gtf-B alleles were identified here, which showed low genetic differentiation in the network. Caries experience was correlated with CFU/mL, but not with allele variation. Low differentiation was found among the 70 alleles recovered from the 358 sequences and among the countries analyzed. CONCLUSION: In this study, caries experience in children was correlated with the number of CFU/mL of S. mutans but not with the gtf-B gene variability. Combined genetic analyses of worldwide strains support the theory that this bacterium experienced population expansions, probably associated with agriculture development and/or food industrialization.

Seguridad Alimentaria y situación nutricional en comedores comunitarios durante el Covid-19 / Food safety and nutritional situation in community kitchens during Covid-19

En la pandemia COVID-19 en los barrios del Área Metropolitana de Buenos Aires se han multiplicado las ollas y comedores comunitarios. Estos espacios tienen gran relevancia en el ejercicio del derecho humano a la alimentación de familias pobres. La presente investigación, de tipo exploratoria, transversal y descriptiva, triangula metodología de investigación cuantitativa y cualitativa, utilizando diferentes técnicas la encuesta "Escala de Experiencia de Inseguridad Alimentaria" (FIES) de FAO, entrevistas en profundidad, observación participante y recordatorios de 24 horas. Tiene por objetivo conocer el estado de seguridad alimentaria y nutricional de referentes e integrantes de ollas y comedores comunitarios del Área Metropolitana de Buenos Aires durante la pandemia COVID-19. Registrando las representaciones y hábitos relacionados a la alimentación, estrategias de aprovisionamiento de alimentos, y cambios ocurridos en la pandemia. Se observó que en Covid-19 la seguridad alimentaria de referentes e integrantes de comedores comunitarios se vio afectada negativamente. Varias de las dimensiones de la Seguridad Alimentaria fueron vulneradas, esto se reflejó en alimentaciones monótonas y de baja calidad nutricional. La Encuesta FIES arrojó que el 75,68% (+8.66) padeció inseguridad alimentaria moderada/severa mientras que más de 37,27% (+9.48) severa, habiendo pasado, por lo menos un día sin comer el último año. Por este motivo se adoptaron diversas estrategias de aprovisionamiento, como el sostenimiento de ollas y comedores comunitarios, la búsqueda de donaciones, la diversificación de los lugares de compra, la sobrecarga de tareas de cuidado, la percepción de políticas de transferencias de ingresos y de módulos de asistencia alimentaria. Los consumos son condicionados por estos últimos, siendo el Estado el principal proveedor de los productos ultraprocesados mencionados en las entrevistas, y favoreciendo de esta manera la situación de malnutrición.

Caries and genetic variability of streptococcus mutans / Caries y variabilidad genética de streptococcus mutans

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.

En las últimas dos décadas el incremento de los estudios de genética de poblaciones ha contribuido a dilucidar cuestiones importantes sobre la evolución de la patogénesis de bacterias de interés clínico. El objetivo de este trabajo es realizar una actualización sobre los conocimientos de los últimos quince años referidos a la variabilidad genética de Streptococcus mutans y su relación con la caries dental. Streptococcus mutans, de amplia distribución mundial, es una de las bacterias más fuertemente asociada a dicha enfermedad. En este trabajo se muestran resultados de numerosos estudios realizados en diferentes países que utilizando métodos moleculares y bioquímicos revelaron asociaciones entre diferentes serotipos y la actividad de caries. Además, se reporta que la estructura genética poblacional de Streptococcus mutans de Argentina es de alto nivel recombinante, lo que reflejaría las grandes oleadas inmigratorias humanas ocurridas en los siglos 19thy 20th. Por otra parte, los análisis demográficos sugieren que esta bacteria experimentó una expansión poblacional coincidente con el comienzo del desarrollo de la agricultura

Urban Populations of Aedes aegypti (Diptera: Culicidae) From Central Argentina: Dispersal Patterns Assessed by Bayesian and Multivariate Methods.

Aedes aegypti (L.), the main vector of dengue and other arboviruses, was declared eradicated from Argentina in 1964; however, in 1987, it was detected again and nowadays it occurs in most of the country territory. To understand the transmission of vector-borne diseases, knowledge of the dispersal of vector populations is essential to evaluate the risk of pathogen transmission. We conducted a population genetic analysis of Ae. aegypti in 20 neighborhoods from Córdoba, the second largest city in Argentina, using 10 microsatellite loci. High genetic differentiation and the absence of an isolation by distance pattern was found using Weir and Cockerham's θ. Bayesian and multivariate clustering analyses showed that the studied sites included individuals with high membership coefficients (Q) in their populations, individuals with membership in another cluster, and admixed individuals. Individuals with high Q in clusters different from the population in which they were collected strongly suggests that passive transport is important in shaping the Ae. aegypti dispersal pattern in Córdoba city. Knowing the genetic structure of Ae. aegypti populations and their dispersal patterns would contribute to the implementation of vector control programs.

Synthesis of highly functionalised enantiopure bicyclo[3.2.1]- octane systems from carvone.

The commercially available monoterpene carvone has been efficiently converted into the tricyclo[3.2.1.0(2.7)]octane and bicyclo[3.2.1]octane systems characteristic of some biologically active compounds. The sequence used for this transformation involves as key features an intramolecular Diels-Alder reaction of a 5-vinyl-1,3-cyclohexadiene and a cyclopropane ring opening.