Molecular Characterization of Four Mexican Isolates of Trypanosoma cruzi and Their Profile Susceptibility to Nifurtimox

PURPOSE

The objective of this study was to molecularly characterize Mexican isolates of T. cruzi obtained from infected triatomine bugs (the vectors of T. cruzi) and to evaluate their susceptibility to Nifurtimox (NFX).

METHODS

Three isolates obtained from Triatoma dimidiata (collected in the State of Veracruz) and one isolate obtained from Triatoma bassolsae (collected in the State of Puebla) were molecularly characterized and the expression of genes associated with natural resistance to NFX was analyzed by qPCR.

RESULTS

Molecular characterization by PCR showed that isolates Zn3, Zn5, and SRB1 belong to the DTU TcI, while isolate Sum3 belongs to TcIV. The latter was also confirmed by sequencing of mitochondrial genes. Isolate Zn5 was the most sensitive to treatment with NFX (IC50, 6.8 μM), isolates SRB1 and Zn3 were partially resistant (IC50, 12.8 μM and 12.7 μM) and isolate Sum3 showed a high degree of resistance to NFX (IC50, 21.4 µM). We also found an association between decreased NTR1 or OYE gene expression with NFX resistance.

CONCLUSION

Our results also evidenced a high variability in the susceptibility to NFX of these T. cruzi isolates Central and Southeastern Mexico, suggesting the presence of naturally resistant isolates circulating in the country. These results have important implications for defining treatment policies for patients with Chagas disease.

Landscape Anthropization Affects Mosquito Diversity in a Deciduous Forest in Southeastern Mexico

Mosquitoes (Diptera: Culicidae) are considered the group of insects that most impacts human health. Land use change, conversion of conserved sites into agricultural environments, urbanization, defaunation, and introduction of domestic animals can affect mosquito diversity positively or negatively, increasing the risk of transmission of zoonotic diseases. Here, we describe the diversity of adult mosquitoes in two environments (deciduous forest and anthropized zone) over 2 yr (2014-2016), using eight CDC traps at each site in three climatic seasons (rainy, cold, and dry). We captured 795 individuals belonging to 22 species. We constructed rank-abundance curves to determine spatial and temporal changes in the mosquito communities. We measured alpha diversity using the Shannon index (H'), Shannon exponential (eH) and Simpson dominance (Ds), and beta diversity using Jaccard's coefficient of similarity (Ij). The most abundant species were Culex quinquefasciatus (40.5%), Culex coronator (18.3%), and Anopheles pseudopunctipennis (12.4%). The highest mosquito diversity was in the deciduous forest during the rainy season. Beta diversity analysis showed that species overlap varied among climatic seasons, with the sites sharing 65% species during the rainy season, but only 33% of species during the dry season. We found differences in the diversity of mosquitoes at the two sites, and the mosquito assemblage of the anthropized zone was significantly different from that of the deciduous forest.

Environmental interactions between people and birds in semiarid lands of the Zapotitlán Valley, Central Mexico

BACKGROUND

Birds have been among the most important element in lives of humans around the world, due to their presence and abundance in practically all ecosystems. Zapotitlán Salinas, a community of the Tehuacán Valley, has been a site of interest for studying ecology of bird communities, but no previous studies addressing the relationship between humans and birds have been conducted in the area. Based on their local knowledge, people of the area shape the use and conservation of local bird fauna diversity, which is being maintained or lost under the influence of factors like commerce, tourism, agriculture intensification or abandonment, public policies for conservation, environmental changes, among others. This study aims to analyze the patterns of interactions between humans and birds in a context of high biocultural diversity with a long history and facing the environmental and social challenges of semiarid areas.

METHODS

Ecological sampling for documenting bird species richness was conducted from November 2015 to May 2017 in three transects that included agroforestry systems, forests, and fallow agricultural land. The method of counting by fixed radius points at 16 points within the study systems was used. Thirty in-depth interviews were conducted with local people who own land in the study areas by random sampling and choosing experts of Zapotitlán Salinas, Puebla, a semiarid natural protected area and, since 2019, recognized as Mixed World Heritage. Some visitor guides of the Helia Bravo Hollis Botanical Garden who are member of the community and local people who dedicated part of their time to catching birds were considered as local experts. They have experience in identifying birds through bird watching and listening to bird songs, as well as their knowledge on behavior and habits of the bird species occurring in their locality. We in addition conducted free listing of bird species recognized by people and interviews on ecological aspects, forms of use, and management of birds using a photographic catalog as visual stimulus. The following aspects were addressed with local people: (i) the bird species of Zapotitlán recognized by them; (ii) the biological, ecological, and behavioral knowledge about these species; (iii) the description of practices of use and management of these animals; (iv) the perceived changes regarding presence and abundance of the wild birds recognized; and (v) the regulations of these practices and uses.

RESULTS

Through the ecological sampling, we identified 89 bird species, a number representing nearly 68% of all species reported for the Zapotitlán Valley. The species recorded belong to 61 genera, 26 families, and 11 orders. Local people interviewed recognized 62 morphospecies occurring in their territory, and designated them with 50 local names. The interactions of local people with birds and the knowledge related to habitats and habits varied according to people's daily life activities and the ways of inter-generational transmission of knowledge. The interactions identified respond to several motivations. The most intense are those of utilitarian nature (three types of use are recognized: nutritional, medicinal, and ornamental), while other less notorious but equally relevant are those related to the awareness and conservation of biological diversity, and aesthetic appreciation of nature. Also relevant are those interactions shaped by the people's worldview since some species are interpreted as climatic environmental predictors, amulets, or omens.

CONCLUSIONS

To understand the various human-bird environmental interactions, it is necessary not only to address the utilitarian assessment that species have in a specific place but also those associated with cultural expressions and the connection between these aspects. Lifestyles, traditions, and beliefs model intangible forms of use, such as the interpretation of climate predictors. Ancient roles of birds in local culture are ongoing, and new demand of ornamental birds from cities influences catching activities but local and regional regulations have contributed to maintain them below a critical level.

LDLR Gene Mutation p.Asp360His and Familial Hypercholesterolemia in a Mexican Community

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by an increased LDL-cholesterol (LDLc) serum concentration and premature cardiovascular disease. Screening of small populations where at least one homozygous (HoFH) patient has been identified may be a proper approach for detecting FH patients. Previously, we reported an HoFH patient carrying the mutation p.Asp360His LDLR, who was born in the Mexican community El Triunfo (Quimixtlan, Puebla).

AIM OF THE STUDY

To identify patients with familial hypercholesterolemia in the community El Triunfo and to describe their clinical and biochemical characteristics.

METHODS

We studied 308 individuals by quantifying lipid levels and by DNA sequencing.

RESULTS

Sixteen of 308 individuals presented an LDLc level >170 mg/dL and all of them turned out to be heterozygous for the LDLR p.Asp360His variant. Subsequently, 34 of their first-degree relatives (mainly siblings and parents) were genotyped rendering six additional HeFH patients, which resulted in 22 carriers of the mutated allele. The study of six LDLR polymorphisms in four unrelated individuals from the community (one HoFH and three HeFH) showed the same haplotype combination, suggesting a unique ancestral origin of the mutation.

CONCLUSIONS

The community El Triunfo, has the highest worldwide frequency ever reported of HeFH, with 7.14% (22/308, equivalent to 1/14 inhabitants). Since the HeFH patients showed variable biochemical expression, we suggest looking for factors with the potential to modify the phenotype. Finally, we stress the importance of establishing accurate LDLc cut-off points applicable to Mexican population for the diagnosis of FH.

Metal concentrations in aquatic environments of Puebla River basin, Mexico: natural and industrial influences

The rapid urban expansion and presence of volcanoes in the premises of Puebla River basin in central Mexico exert significant influences over its aquatic environments. Twenty surface sediment samples from Puebla River basin consisting of R. Alseseca, R. Atoyac, and Valsequillo dam were collected during September 2009 and analyzed for major (Al, Fe, Mg, Ba, Ca, and K) and trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) in order to identify the metal concentrations and their enrichment. R. Atoyac sediments presented higher concentrations of Ba (1193.8 μg g^-1) and Pb (27.1 μg g^-1) in comparison with the local reference sample values. All the metal concentrations except Sr for R. Alseseca sediments were within the range of local reference sample values indicating no significant external influence, whereas Valsequillo dam sediments had elevated concentrations of all the metals suggesting both natural and external influences in the study region. The magnitude of metal contamination was assessed using several indices such as geoaccumulation index (I _geo), enrichment factor (EF), degree of contamination (C _d ), and pollution load index (PLI). The results suggest that As, Pb, and Zn were predominantly enriched in the Puebla River basin sediments. Comparing with sediment quality guidelines and ecotoxicological values, it is revealed that Cd, Cr, Cu, and Ni have possible harmful effects on the biological community. The present study provides an outlook of metal enrichment in Puebla River basin sediments, highlighting the necessity to conserve this river ecosystem for the near future.

Application of water quality index to evaluate groundwater quality (temporal and spatial variation) of an intensively exploited aquifer (Puebla valley, Mexico)

The spatial and temporal variation of water quality in the urban area of the Puebla Valley aquifer was evaluated using historical and present data obtained during this investigation. The current study assessed water quality based on the Water Quality Index developed by the Canadian Council of Ministers of the Environment (CCME-WQI), which provides a mathematical framework to evaluate the quality of water in combination with a set of conditions representing quality criteria, or limits. This index is flexible regarding the type and number of variables used by the evaluation given that the variables of interest are selected according to the characteristics and objectives of development, conservation and compliance with regulations. The CCME-WQI was calculated using several variables that assess the main use of the wells in the urban area that is public supply, according to criteria for human use and consumption established by Mexican law and international standards proposed by the World Health Organization. The assessment of the index shows a gradual deterioration in the quality of the aquifer over time, as the amount of wells with excellent quality have decreased and those with lower index values (poor quality) have increased throughout the urban area of the Puebla Valley aquifer. The parameters affecting groundwater quality are: total dissolved solids, sulfate, calcium, magnesium and total hardness.

A new species of earth snake (Dipsadidae, Geophis) from Mexico

A new species of the Geophisdubius group is described from the mountains of the Sierra Zongolica in west-central Veracruz and the Sierra de Quimixtlán in central-east Puebla. The new species is most similar to Geophisduellmani and Geophisturbidus, which are endemic to the mountains of northern Oaxaca and the Sierra Madre Oriental of Puebla and Hidalgo, respectively. However, the new species differs from Geophisduellmani by the presence of postocular and supraocular scales and from Geophisturbidus by having a bicolor dorsum. With the description of the new species, the species number in the genus increases to 50 and to 12 in the Geophisdubius group. Additionally, a key to the species of the Geophisdubius group is provided.

Significant clinical impact of recurrent BRCA1 and BRCA2 mutations in Mexico

BACKGROUND

Frequent recurrent mutations in the breast and ovarian cancer susceptibility (BRCA) genes BRCA1 and BRCA2 among Hispanics, including a large rearrangement Mexican founder mutation (BRCA1 exon 9-12 deletion [ex9-12del]), suggest that an ancestry-informed BRCA-testing strategy could reduce disparities and promote cancer prevention by enabling economic screening for hereditary breast and ovarian cancer in Mexico.

METHODS

In a multistage approach, 188 patients with cancer who were unselected for family cancer history (92 with ovarian cancer and 96 with breast cancer) were screened for BRCA mutations using a Hispanic mutation panel (HISPANEL) of 115 recurrent mutations in a multiplex assay (114 were screened on a mass spectroscopy platform, and a polymerase chain reaction assay was used to screen for the BRCA1 ex9-12del mutation). This was followed by sequencing of all BRCA exons and adjacent intronic regions and a BRCA1 multiplex ligation-dependent probe amplification assay (MLPA) for HISPANEL-negative patients. BRCA mutation prevalence was calculated and correlated with histology and tumor receptor status, and HISPANEL sensitivity was estimated.

RESULTS

BRCA mutations were detected in 26 of 92 patients (28%) with ovarian cancer, in 14 of 96 patients (15%) with breast cancer overall, and in 9 of 33 patients (27%) who had tumors that were negative for estrogen receptor, progesterone receptor, and human epithelial growth factor 2 (triple-negative breast cancer). Most patients with breast cancer were diagnosed with locally advanced disease. The Mexican founder mutation (BRCA1 ex9-12del) accounted for 35% of BRCA-associated ovarian cancers and 29% of BRCA-associated breast cancers. At 2% of the sequencing and MLPA cost, HISPANEL detected 68% of all BRCA mutations.

CONCLUSIONS

In this study, a remarkably high prevalence of BRCA mutations was observed among patients with ovarian cancer and breast cancer who were not selected for family history, and the BRCA1 ex9-12del mutation explained 33% of the total. The remarkable frequency of BRCA1 ex9-12del in Mexico City supports a nearby origin of this Mexican founder mutation and may constitute a regional public health problem. The HISPANEL mutation panel presents a translational opportunity for cost-effective genetic testing to enable breast and ovarian cancer prevention.