RESUMEN
Variation in the length and copy number of intergenic spacers (IGS) of nuclear ribosomal DNA were examined to test for genetic differentiation among Anopheles albimanus populations. Extensive collections were made in Guatemala but populations were also sampled over a large range of its distribution in Central and South America. Discriminant analysis of IGS patterns in individual mosquitoes indicated that populations generally had unique sets of IGS length variants. The IGS patterns from populations on the Pacific side of Central America were distinct from those on the Atlantic side or from South America. Cluster analysis indicated a similar trend. The IGS diversity in Central America was 50% greater than in South America. These results suggest that barriers to gene flow exist among Atlantic and Pacific coast populations of An. albimanus. No gene flow barriers were detected among populations from Colombia, Ecuador, Peru, and Venezuela.
Asunto(s)
Anopheles/genética , ADN Ribosómico/genética , Variación Genética , Insectos Vectores/genética , Animales , América Central , Análisis por Conglomerados , Análisis Discriminante , Frecuencia de los Genes , México , América del SurRESUMEN
To determine the prevalence and causes of anemia in rural Mexico, blood samples and longitudinal dietary data were collected from 187 women, some pregnant and then lactating, and from 72 men. Blood was used to measure anemia, mean cell volume, and plasma ferritin, folate and vitamin B-12. Anemia was found in 33% of the men, 54% of nonpregnant, nonlactating women, 35% of pregnant women and 41% of lactating women, and varied by season. Low iron stores (ferritin) accompanied anemia in only 8% of men compared with 38-67% of women. Low meat intake and poor dietary iron bioavailability were associated with anemia in women. There were no cases of low plasma folate. Low plasma vitamin B-12 was common in all groups, and the incidence increased from 15% at 7 mo of pregnancy to 30% at 7 mo of lactation. Vitamin B-12 was lower in the plasma and milk of anemic lactating women than in plasma and milk of non-anemic lactating women and was classified as deficient in 62% of breast milk samples.