Biological information is widely available for the 13 most common domestic triatomines (Hemiptera: Reduviidae: Triatominae) among the 30 species described in Mexico (Martínez-Ibarra et al. 2007, Salazar-Schettino et al. 2010). Information about the remaining species is scarce, primarily because these species have rarely been collected and are difficult to raise under laboratory conditions. Three of these rare species are Triatoma recurva (Stal), Triatoma protracta (Uhler) and Triatoma rubida (Uhler). Although these three species are considered to be of low epidemiological importance, specimens of at least two of these species (T. recurva and T. rubida) collected from inside human dwellings were found to be infected with Trypanosoma cruzi (Paredes-González et al. 2001, Licón-Trillo 2006, Breniere et al. 2010, Licón-Trillo et al. 2010. Studies on the behaviour of triatomine species provide a greater understanding of the habits of these insects and therefore facilitate improved decision-making regarding the priorities for vector control. To our knowledge, there has been no study of the biological parameters (life cycle and feeding and defecation behaviours) of T. recurva; in contrast, two recent studies were devoted to the examination of certain behaviours of T. protracta (Martínez-Ibarra et al. 2007, Klotz et al. 2009) and three studies focused on T. rubida (Martínez-Ibarra et al. 2005, Klotz et al. 2009, Reisenman et al. 2011. Even though the biological parameters of the two latter species have been studied previously, it is necessary to determine the particular behaviours of geographically distinct populations of the same species because it is likely that differing environmental conditions result in different behaviours for distinct populations of the same triatomine species (Licón-Trillo et al. 2010).As part of a series of studies on the biology of Mexican Triatominae, a study of the feeding and defecation behaviours and the life cycles of three Triatominae species of secondary importance in the transmission of T. cruzi to human populations in Mexico was conducted. MATERIALS AND METHODSA laboratory colony of T. recurva established in 2009 from specimens collected in Jesús María, Nayarit, Mexico, was used. A colony of T. protracta (morphologically similar to the synonymised subspecies protracta) was established in 2008 with specimens originally obtained from Caborca, Sonora, Mexico. In addition, a colony of T. rubida (morphologically similar to the synonymised subspecies uhleri) from Saucillo, Chihuahua, was included. The colonies were maintained at 25ºC ± 1ºC and 50% relative humidity (RH) ± 5% RH to match the typical habitat conditions of the three species. The colonies were fed on immobilised and anaesthetised New Zealand rabbits on a weekly basis. These rabbits were anaesthetised following the Norma Official Mexicana regulations with 0.25 mL/kg of ketamine delivered intramuscularly (SAGARPA 1999
Nine- to twelve-week-old BALB/c mice were injected in footpads with 107 CFU of a Nocardia brasiliensis cell suspension. Typical actinomycetoma lesions, characterized by severe local inflammation with abscess and fistula formation, were fully established by day 28 after infection. These changes presented for 90 days, and then tissue repair with scar formation slowly appeared, with complete healing after 150 days of infection. Some animals developed bone destruction in the affected area. Histopathology showed an intense inflammatory response, with polymorphonuclear cells and hyaloid material around the colonies of the bacteria, some of which were discharged from draining abscesses. Sera from experimental animals were analyzed by Western blotting, and immunodominant antigens P61 and P24 were found as major targets for antibody response. Anti-P24 immunoglobulin M (IgM) isotype antibodies were present as early as 7 days, IgG peaking 45 days after infection. Lymphocyte proliferation with spleen and popliteal lymph node cells demonstrated thymidine incorporation at 7 days after infection, the stimulation index decreasing by day 60. Levels of interleukin-1 (IL-1), IL-2, IL-4, IL-6, tumor necrosis factor alpha, and gamma interferon (IFN-γ) were determined by enzyme-linked immunosorbent assay in the sera of infected animals. The circulating levels of IFN-γ increased more than 10 times the basal levels; levels of IL-4, IL-6 and IL-10 also increased during the first 4 days of infection.
The degree of reproductive isolation between Triatoma recurva (Stål) (Hemiptera: Reduviidae: Triatominae) and the six species of the genus Meccus plus T. mexicana (Herrich-Schaeffer) (Hemiptera: Reduviidae) was examined. Fertility and the segregation of morphological characteristics were examined in two generations of hybrids from crosses between these species. The percentage of couples with offspring (fertile) was low in the vast majority of sets of crosses, with the exception of that between T. recurva female and M. phyllosomus male. In all studied sets of crosses, no first-(F1) or second-(F2) generation individuals were morphologically similar to T. recurva but instead shared the morphology of the other parental species. A similar phenomenon was observed in the three successful sets of backcrosses. These results indicated that different recorded levels of reproductive fitness among T. recurva and the species of Meccus involved in this study, plus T. mexicana, are present and that they were apparently influenced by differing mechanisms of isolation. The presence of some degree of reproductive compatibility between studied triatomines of distinct genera (Meccus spp. and Triatoma spp.) reinforces the need for generic revision of the tribe Triatomini. Journal of Vector Ecology 40 (1): 117-121. 2015.
The GSTT1 and GSTM1 genes are key molecules in cellular detoxification. Null variants in these genes are associated with increase susceptibility to developing different types of cancers. The aim of this study was to determine the prevalence of GSTT1 and GSTM1 null genotypes in Mestizo and Amerindian individuals from the Northwestern region of Mexico, and to compare them with those reported worldwide. GSTT1 and GSTM1 null variants were genotyped by multiplex PCR in 211 Mestizos and 211 Amerindian individuals. Studies reporting on frequency of GSTT1 and GSTM1 null variants worldwide were identified by a PubMed search and their geographic distribution were analyzed. We found no significant differences in the frequency of the null genotype for GSTT1 and GSM1 genes between Mestizo and Amerindian individuals. Worldwide frequencies of the GSTT1 and GSTM1 null genotypes ranges from 0.10 to 0.51, and from 0.11 to 0.67, respectively. Interestingly, in most countries the frequency of the GSTT1 null genotype is common or frequent (76%), whereas the frequency of the GSMT1 null genotype is very frequent or extremely frequent (86%). Thus, ethnic-dependent differences in the prevalence of GSTT1 and GSTM1 null variants may influence the effect of environmental carcinogens in cancer risk.
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