Browsing by Autor "Jean Dujardin"

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Evolutionary relationships based on genetic and phenetic characters between Triatoma maculata, Triatoma pseudomaculata and morphologically related species (Reduviidae: Triatominae)
(Elsevier BV, 2007) Silvia Menezes dos Santos; Catarina Macedo Lopes; Jean Dujardin; Francisco Panzera; Ruben Pérez; Ana Laura Carbajal-de-la-Fuente; R. S. Pacheco; François Noireau
Genomic Changes of Chagas Disease Vector, South America
(Centers for Disease Control and Prevention, 2004) Francisco Panzera; Jean Dujardin; Paula Nicolini; Marı́a Noel Caraccio; Virginia De Rose; Tatiana Tellez; Hernán Bermúdez; M. Dolores Bargues; Santiago Mas‐Coma; José‐Enrique O’Connor
We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4-7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments.
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.
Metric Differences Between Silvatic and Domestic Triatoma infestans (Heteroptera: Reduviidae) in Bolivia
(Oxford University Press, 1997) Jean Dujardin; Harry Bermudez; CE Casini; Christopher J. Schofield; Michel Tibayrenc
One hundred and fifty-seven specimens of Bolivian Triatoma infestans (Klug 1834), including 44 from the silvatic focus at Cochabamba (Bolivia), were compared using morphometric characters of the head capsule. From these specimens, 10 silvatic and 28 domestic adults were also compared using additional morphometric characters of the membranous part of the hemelytra. Nonparametric univariate comparisons between specimens from silvatic and domestic ecotopes indicated the importance of the postocular region as a possible diagnostic character for nymphs and adults from the different ecotopes, and they detected wing differences in males. Populations became more distinct entities when head or wing characters were considered jointly in canonical variate analysis. Regardless of whether size variation was considered, canonical variate analysis generally showed greater significance for wing than for head features. These morphological differences between silvatic and domestic bugs, particularly unrelated to size differences, are interpreted to indicate incipient separation between silvatic and domestic populations that had not been detected by previous isoenzyme analyses, and suggest a reinterpretation of the epidemiological significance of silvatic populations of T. infestans in Bolivia.
Population morphometric analysis of the tropicopolitan bug <i>Triatoma rubrofasciata</i> and relationships with Old World species of <i>Triatoma</i> : evidence of New World ancestry
(Wiley, 2001) James Patterson; Christopher J. Schofield; Jean Dujardin; Michael A. Miles
Quantitative analysis of morphological characters of the head was used to reconstruct the evolutionary history of the tropicopolitan bug Triatoma rubrofasciata (De Geer) (Hemiptera: Reduviidae) and seven species of Old World Triatoma. Multivariate analysis demonstrates that T. rubrofasciata and the Old World species have a high degree of similarity with Nearctic Triatoma species, particularly T. rubida (Uhler). We interpret this to imply a common ancestry for these groups. Dissemination of T. rubrofasciata and subsequent derivation of the Old World species of Triatoma is deduced to have occurred over a period of not more than 350 years.