Chagas Cardiomyopathy Manifestations and Trypanosoma cruzi Genotypes Circulating in Chronic Chagasic Patients

Chagas disease caused by Trypanosoma cruzi is a complex disease that is endemic and an important problem in public health in Latin America. The T. cruzi parasite is classified into six discrete taxonomic units (DTUs) based on the recently proposed nomenclature (TcI, TcII, TcIII, TcIV, TcV and TcVI). The discovery of genetic variability within TcI showed the presence of five genotypes (Ia, Ib, Ic, Id and Ie) related to the transmission cycle of Chagas disease. In Colombia, TcI is more prevalent but TcII has also been reported, as has mixed infection by both TcI and TcII in the same Chagasic patient. The objectives of this study were to determine the T. cruzi DTUs that are circulating in Colombian chronic Chagasic patients and to obtain more information about the molecular epidemiology of Chagas disease in Colombia. We also assessed the presence of electrocardiographic, radiologic and echocardiographic abnormalities with the purpose of correlating T. cruzi genetic variability and cardiac disease. Molecular characterization was performed in Colombian adult chronic Chagasic patients based on the intergenic region of the mini-exon gene, the 24Sα and 18S regions of rDNA and the variable region of satellite DNA, whereby the presence of T.cruzi I, II, III and IV was detected. In our population, mixed infections also occurred, with TcI-TcII, TcI-TcIII and TcI-TcIV, as well as the existence of the TcI genotypes showing the presence of genotypes Ia and Id. Patients infected with TcI demonstrated a higher prevalence of cardiac alterations than those infected with TcII. These results corroborate the predominance of TcI in Colombia and show the first report of TcIII and TcIV in Colombian Chagasic patients. Findings also indicate that Chagas cardiomyopathy manifestations are more correlated with TcI than with TcII in Colombia

American marsupials chromosomes: Why study them?

Marsupials, one of the three main groups of mammals, are only found in Australia and in the American continent. Studies performed in Australian marsupials have demonstrated the great potential provided by the group for the understanding of basic genetic mechanisms and chromosome evolution in mammals. Genetic studies in American marsupials are relatively scarce and cytogenetic data of most species are restricted to karyotype descriptions, usually without banding patterns. Nevertheless, the first marsupial genome sequenced was that of Monodelphis domestica, a South American species. The knowledge about mammalian genome evolution and function that resulted from studies on M. domestica is in sharp contrast with the lack of genetic data on most American marsupial species. Here, we present an overview of the chromosome studies performed in marsupials with emphasis on the South American species

Variación citogenética, molecular y morfologica de un nuevo mamífero aislado en Chile central: ¿Nueva especie para la ciencia?

Unreported pecimens of the genus Eligmodontia (Mammalia, Rodentis) were found in north-central Chile, which differ in geographical distribution and morphology with knowm species. We test the null hypothesis that such Eligmodontia sp (ES) belongs to an already described species, perhaps E. puerulus (EP) or E. hirtipes (EH) from northern Chile. We took six body measurements and compared those from ES (n=19 individuals), EP (n=20), and EH (n=34) (t-test of 2 samples by means of the program STATA). We also compared number and morphology of chromosomes, from bone-marrow metaphase plates of three ES individuals. The chromosome number of ES (2n=50, NF=48) was the same to that of EH. Finally, we analyzed 10 sequences of 935 bp of the cytochrome b gene from ES, which were aligned and compared with those from all of the other species of Eligmodontia obtained from GenBank (MEGA5 program, bootstrap with 500 replicas). Results were significant statistically different in morphological and gene sequence comparisons between different species. The intraspecies distances obtained (mean d=6,7 nucleotides) were all smaller by an order of magnitude than interspecies distances (mean d=82,6 nucleotides), including those of ES vs. EH (d=92,6 nucleotides). The ES node had a 100% bootstrap. These results, and the consideration of geographic distribution and the evolutionary definition of species (Simpson 1961). we reject the null hypothesis, and postulate the need of describing a new mammal species, endemic for Chile. Keywords: Eligmodontia, mammal, new species, Atacama desert.Recientemente fueron encontrados especímenes no reportados del género Eligmodontia (Mammalia, Rodentia) en Chile Norte-Central, que difieren en distribución geográfica y morfología con especies ya conocidas. Ponemos a prueba la hipótesis nula de que tales Eligmodontia sp (ES) pertenecen a una especie ya descrita, posiblemente E. puerulus (EP) o E. hirtipes (EH), del Norte de Chile. Realizamos seis medidas corporales, y comparamos las de ES (n=19 individuos), EP (n=20), y EH (n=34) (test de t para 2 muestras por medio del programa STATA). También comparamos el número y la morfología de sus cromosomas, obteniendo placas metafásicas de médula ósea de tres individuos ES. El número cromosómico obtenido de ES (2n=50, NF=48) coincide con el de EH. Finalmente, analizamos 10 secuencias de 935 pb del gen para citocromo b de ES, que fueron alineadas y comparadas con las de todas las otras seis especies de Eligmodontia (n=53) obtenidas desde GenBank (programa MEGA5, Bootstrap con 500 réplicas). Los resultados arrojaron diferencias estadísticamente significativas en cuanto a las comparaciones morfológicas y de las secuencias del gen para el citocromo b entre las distintas especies. Las distancias intraespecies obtenidas (promedio d=6,7 nucleótidos) fueron todas menores en un orden de magnitud a las interespecies (promedio d=82,6 nucleótidos), incluyendo las de ES vs EH (d=92,6 nucleótidos). El nodo ES resultó con 100% bootstrap. Con estos resultados, y considerando la distribución geográfica y la definición evolutiva de especie (Simpson 1961), rechazamos la hipótesis nula, y postulamos la necesidad de describir una nueva especie de mamífero, endémico para Chile

Radiation of extant marsupials after the K/T boundary: Evidence from complete mitochondrial genomes

The complete mitochondrial (mt) genomes of five marsupial species have been sequenced. The species represent all three South American orders (Didelphimorphia, Paucituberculata, and Microbiotheria). Phylogenetic analysis of this data set indicates that Didelphimorphia is a basal marsupial lineage followed by Paucituberculata. The South American microbiotherid Dromiciops gliroides (monito del monte) groups with Australian marsupials, suggesting a marsupial colonization of Australia on two occasions or, alternatively, a migration of an Australian marsupial lineage to South America. Molecular estimates suggest that the deepest marsupial divergences took place 64–62 million years before present (MYBP), implying that the radiation of recent marsupials took place after the K/T (Cretaceous/ Tertiary) boundary. The South American marsupial lineages are all characterized by a putatively nonfunctional tRNA for lysine, a potential RNA editing of the tRNA for asparagine, and a rearrangement of tRNA genes at the origin of light strand replication