RESUMEN
We analysed a representative collection of New World sweet potato landraces (329 accessions from Mexico to Peru) with both chloroplast and nuclear microsatellite markers. Both kinds of markers supported the existence of two geographically restricted genepools, corresponding to accessions from the north-western part of South America and accessions from the Caribbean and Central America region. Our conservative cpSSRs markers revealed that the divergence between the two haplotype groups is associated with numerous mutation events concerning various markers, supporting the idea that this divergence may be ancient, predating domestication. For both kinds of markers, we found no significant difference in diversity between the two genepools and detected region-specific alleles in both groups. Previous studies have favoured the hypothesis of a single domestication of this crop. Our analysis suggests at least two independent domestications, in Central/Caribbean America and in the north-western part of South America. Sweet potato was then dispersed from these centres throughout tropical America. Comparison of nuclear and chloroplast data suggests that exchanges of clones and sexual reproduction were both important processes in landrace diversification in this clonally propagated crop. Our analysis provides useful tools for rationalizing the conservation and use of sweet potato germplasm collections.
Asunto(s)
Núcleo Celular/genética , Cloroplastos/genética , Ipomoea batatas/genética , Repeticiones de Microsatélite , Dispersión de Semillas , América Central , Variación Genética , Geografía , Haplotipos , Ipomoea batatas/fisiología , México , Filogeografía , Dinámica Poblacional , América del SurRESUMEN
A prospective, triple-blind study was undertaken to determine whether antiheart antibody or a rise in titer to a virus occurred in patients after intrapericardial surgery and, if so, whether either was related to clinical evidence of the postpericardiotomy syndrome. In 257 patients, AHA in high titer appeared in 62 (24%), all of whom had the syndrome. None of the 102 patients with no AHA had the syndrome. In 137 subjects, a rise in titer to one or more viral agents occurred in 21 of 31 (68%) of those with AHA and PPS. This study suggests that an immunologic response and viral illness are related to PPS.