Browsing by Autor "Francisco J. Ayala"

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    Additional data on Trypanosoma cruzi isozymic strains encountered in Bolivian domestic transmission cycles
    (Oxford University Press, 1986) Michel Tibayrenc; Ary A. Hoffmann; Olivier Poch; Lourdes Echalar; François Le Pont; Jean-Loup Lemesre; P. Desjeux; Francisco J. Ayala
    We have collected in Bolivia 212 stocks of Trypanosoma cruzi from domestic transmission cycles and have assayed for nine enzyme systems (11 gene loci). Only a few different isozyme profiles exist, without recombination between them, a situation also encountered in previous Bolivian samples. The 212 stocks, combined with 207 stocks previously studied, have been analysed to uncover any spatial patterns. The frequency of heterozygous strains (2 and 2a) decreases westwards and with increasing altitude. Given that longitude and altitude are correlated with each other, it is not possible to decide which of these two geographic variables is the relevant one, or if both are. These associations might be due to climatic factors. Studies by other authors have shown, however, that heterozygous strains are rare or absent in the Amazon Basin, which is at low altitude.
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    Isozyme Evidence of Lack of Speciation Between Wild and Domestic Triatoma Infestans (Heteroptera: Reduviidae) in Bolivia1
    (Oxford University Press, 1987) Jean Dujardin; Michel Tibayrenc; Evaristo Venegas; Liliana Ximena Muñoz Maldonado; P. Desjeux; Francisco J. Ayala
    Wild and domestic Triatoma infestans from the Cochabamba region of Bolivia were virtually identical at 19 gene loci coding for enzymes. No allele was distinctive of either the wild or the domestic populations. Hence, there is no evidence that the 2 populations are different species. Domestic populations separated by 20 km showed statistically significant differences in allelic frequencies; this is compatible with the hypothesis of other authors that migrations of T. infestans are limited when feeding conditions are satisfactory. Fifteen trypanosomatid stocks isolated from wild T. infestans were shown by isozyme analysis to be Trypanosoma cruzi. This provides evidence that wild T. infestans are involved in the Chagas' disease cycle. The T. cruzi isozymic strains from wild T. infestans were genetically similar to those isolated from domestic T. infestans in the same region. This supports the hypothesis that there is no speciation between wild and domestic T. infestans, and that wild and domestic T. cruzi cycles may overlap in this region.