Zone In Central Mexico Research Articles

Virome of the vegetable prickly pear cactus in the central zone of Mexico

In this study, the ability of high-throughput sequencing (HTS) to detect viruses in vegetable prickly pear cactus was exploited. Samples from State of Mexico (EDMX), Hidalgo, and Morelos, as well as Mexico City (CDMX), were analyzed. In the sample from EDMX, the genomes of Opuntia virus 2 (OV2, genus Tobamovirus) and Cactus carlavirus 1 (CCV-1, genus Carlavirus) were detected and recovered. In the sample from CDMX, in addition to OV2 and CCV-1, a new viroid and potexvirus were detected. The former has a circular RNA genome with a length of 412 nt for which the name “Opuntia viroid I” (OVd-I) is proposed. The primary structure of this viroid showed a nucleotide sequence identity of less than 80% with any of the currently known viroids and a phylogenetic relationship with the genus Apscaviroid (Family Pospiviroidae) with which it shares conserved structural motifs. The new potexvirus was named Opuntia potexvirus A (OPV-A), whose viral replicase sequence has a 77.7 % amino acid identity with Schlumbergera virus X. Finally, CCV-1 was detected in 93 (72 %) of 129 vegetable prickly pear cactus samples collected in the four entities.

Fungal feeding preferences and molecular gut content analysis of two abundant oribatid mite species (Acari: Oribatida) under the canopy of Prosopis laevigata (Fabaceae) in a semi-arid land

Prosopis laevigata (mesquite; Fabaceae) forms fertility islands in soils of semi-arid lands where microbial diversity concentrates in response to the accumulation of resources in the soil beneath individual plants, promoting organic matter decomposition and nutrient cycling. This phenomenon provides suitable conditions for the proliferation of key edaphic elements such as fungi and mites. Mite-fungal interactions are central for our understanding of nutrient cycling processes in resource-limited arid food webs; yet, no information is available about fertility islands in semi-arid lands. Thus, we aimed to determine in vitro fungal-based feeding preferences and molecular gut content of the oribatid mite species Zygoribatula cf. floridana and Scheloribates cf. laevigatus, which are abundant under the canopy of P. laevigata in an intertropical semi-arid zone in Central Mexico. Our results on the gut content analysis of these oribatid species resulted in the ITS-based identification of the following fungi: Aspergillus homomorphus, Beauveria bassiana, Filobasidium sp., Mortierella sp., Roussoella sp., Saccharomyces cerevisiae, Sclerotiniaceae sp. and Triparticalcar sp. Furthermore, under laboratory conditions both oribatid mite species exhibited feeding preferences on melanized fungi, such as Cladosporium spp., whereas A. homomorphus and Fusarium penzigi were avoided. Our findings indicated that the analyzed oribatid mite species have similar feeding preferences for melanized fungi, which might suggest resource partitioning and a degree of preference, explaining the coexistence of both oribatid species.

Contrasting gas exchange effects on the interactions of two mistletoe species and their host Acacia schaffneri

Mistletoes nutrient and water uptake can alter the gas exchange activity of their host plants, leading them to a diminished photosynthetic capacity and poor water use efficiency. This is particularly important in semi-arid areas, where water availability is a limiting factor. The aim of this study was to evaluate gas exchange (photosynthetic net rate (A), stomatal conductance (G) and intrinsic water use efficiency (iWUE)) of uninfected Acacia schaffneri trees, compared to trees infected by two mistletoe species, Psittacanthus calyculatus and Phoradendron brachystachyum, in a semi-arid zone in central Mexico. We also registered the physiological performance of the two-infecting species. All variables were measured in a monthly basis for one year. Physiological parameters for Acacia trees and for the two-mistletoe species, varied along the year, suggesting an important effect of the environmental conditions. Infected versus uninfected trees were not different for A and iWUE, however G in trees infected with P. brachystachyum was significantly lower, particularly on severely infected trees. Mistletoe parameters also varied with time and severity of infection, the latter suggesting a density dependent pattern: P. brachystachyum seems to be competing with its conspecific since A and iWUE were lower when infection was high, whereas P. calyculatus was favored with a greater iWUE when coexisting with its conspecifics. Results suggest that seasonality effect is more important than mistletoe infection in the physiological performance of the host.

Morelos A-2016: variedad de arroz de grano grueso

En la zona central de México se siembra el arroz (Oryza sativa L.) bajo trasplante y en siembra directa bajo riego; la mayoría de las variedades se han liberado para trasplante. En 2005 una de estas líneas se usó como progenitor y continuándose con el avance generacional hasta F5. En 2011 se realizó una prueba preliminar del rendimiento de varios grupos de líneas, alrededor de 256 materiales, de donde se identificó como sobresaliente a C14Za06 (actualmente, var. Morelos A-2016). En 2014 y 2015 se evaluaron diferentes líneas en ensayos de rendimiento en las localidades de Zacatepec, Jojutla, Emiliano Zapata, Mazatepec, Coatlán del Rio y Cuautla, estado de Morelos; además del testigo comercial Morelos A-2010. De los materiales evaluados sobresalió la C14Za06 por rendimiento superior a 10 t ha-1, moderada resistencia a pyricularia, alta tolerancia a manchado de grano, habito de crecimiento semierecto, altura de planta de 130 cm, resistentes al acame; rendimiento en industria de 57% de grano pulido entero; conservando la calidad Morelos (20% de centro blanco).

Three versions of the Short Alcohol Dependence Data Questionnaire (SADD) in Mexican population: a comparative analysis of psychometric properties and diagnostic accuracy

Abstract Background. The Short Alcohol Dependence Data Questionnaire (SADD) has shown good reliability and validity in previous studies. In Mexico, although it is widely used in addiction treatment centers, little is known about its psychometric properties and diagnostic accuracy. Objective. Hence, this study performed a Confirmatory Factorial Analysis (CFA) on three SADD versions (15, 14 and 12 items) and examined their operating characteristics. Method. The sample included 570 individuals from the 30 Addiction Residential Centers localized in the central zone of Mexico. Results. The three versions showed an internal consistency of >.90, fair goodness-of-fit, and significant correlations with the Mini International Neuropsychiatric Interview (MINI) 5.0 Alcohol dependence (AD) diagnostic criteria. The analysis of the operating characteristics revealed that each version accounted for 84-85% of the area under the curve (AUC). Discussion and conclusion. The three SADD versions possess reliability and validity properties for the assessment of the alcohol dependence syndrome (ADS) and adequate diagnostic accuracy for the improvement of patients with AD in residential settings.

Diversity of Ants Inhabiting a Mosaic of Environmental Conditions in a Semi-Desert of Central Mexico

Biotic and abiotic factors affect the species richness and abundance of ants inhabiting arid and semiarid zones. We evaluated how soil surface temperature, texture, percentage of surface coarse fragments, and vegetation affected the composition, diversity, and distribution of ants inhabiting a mosaic of environmental conditions in a semiarid zone in central Mexico. We captured 22 ant species at five sites studied, with the top of Cutac hill (1,750 m altitude) and Terrace 2 (1,376 m altitude) the richest sites with 10 species each. Based on redundancy analyses, the percentage of clay followed by the percentage of coarse fragments at the surface of the soil were the variables most related to the composition of ants in these communities. Percentage of clay ranged from 16 to 26 and was positively related to abundance of Pheidole sp. 1 and negatively related to abundance of Dorymyrmex bureni Trager (R2 = 0.76, P = 0.04; R2 = 0.86, P = 0.02, respectively), whereas percentage of soil surface coarse fragments ranged from 0.8 to 59 and were negatively correlated to Pheidole sp. 1 (R2 = 0.76, P = 0.05), but positively correlated to abundance of Brachymyrmex sp. (R2 = 0.86, P = 0.06). When ants were analyzed by functional group, vegetative structure (ranging from 109 to 246 hits with vegetation) and percentage of coarse fragments in the soil were most correlated with their distribution. Although results of the redundancy analyses were not statistically significant, preliminary analysis of variables might explain the composition and distribution of an ant community. We suggested that soil characteristics might be important for explaining ant distribution and community composition.

Selección y Espaciamiento de Apartarrayos en Líneas de Distribución de 23 kV de la Zona Centro

En este artículo se analiza una red de distribución urbana de 23 kV típica de la zona central de México, para determinar la distancia máxima de separación entre apartarrayos de línea que permita reducir las salidas de los circuitos de distribución por descargas atmosféricas directas e indirectas. Con base en las características eléctricas, ambientales, ceráunicas y geográficas de la zona, niveles de cortocircuito y los sobrevoltajes provocados por maniobras rutinarias, se selecciona el apartarrayos siempre con el principal objetivo de determinar su espaciamiento adecuado sobre la línea para que funcione eficientemente. Esta investigación se lleva a cabo con la ayuda del software Alternative Transients Program (ATP) con el que se realiza desde el cálculo de los parámetros de la línea utilizando el modelo de K.C. Lee, hasta los análisis de sobretensiones transitorias de onda viajera y por conexión de capacitores. La motivación de este trabajo consiste principalmente en contar con un sustento teórico-técnico (actualmente escueto) para determinar el espaciamiento de apartarrayos en redes de distribución y que impacte en el aumento de la calidad del suministro eléctrico.

Feeding interactions in an assemblage of terrestrial carnivores in central Mexico.

We evaluated the strategies of resources partitioning among species, dietary overlap and niche breadth in an assemblage of carnivores integrated by top predators (Puma concolor and Panthera onca) and mesopredators(Leoparduspardalis,Leoparduswiedii,Puma yagouaroundi,Nasuanarica andUrocyoncinereoargenteus). The aim of this study was to investigate the mechanisms explaining the coexistence among species at a temperate zone in central Mexico. We collected 259 scats of carnivores and identified 45 food items. The analysis showed the common consumptionof mammals in the assemblage, and the correspondence analysis showed three guilds: 1) top predators associated with the use of medium-sized mammals and the exclusive consumption of large mammals, 2) carnivore mesopredators associated with the consumption of small mammals and birds and 3) omnivore mesopredators associated with the consumption of arthropods and plants. The dietary overlap analysis indicated a low overlap between guilds and a high overlap within them. Top predators were specialist foragers, whilst the carnivore mesopredators showed generalist consumption. The coexistence in this carnivore assemblage seems to be related to body size, morphology and prey segregation because such characteristics suggest the presence of three guilds. We observed high dietary overlap within guilds and resource partitioning betweenguilds.

The Secular Tendency of the Age at Menarche in a Representative Sample of Mexican Girls from an Urban Zone in Central Mexico

Objective: To investigate the age at menarche, pubarche and telarche in a representative sample of residents of an urban zone of Leon, Guanajuato, Central Mexico and to evaluate the secular change of the age at menarche between 1985 and 2000. Methods: Using status quo and retrospective methods, menarcheal, pubarcheal and telarcheal status of girls 8 - 17 years of age (n = 1093) were determined. Multiple regression analysis and logistic regression were used to determine factors that were related to or predictive of age at menarche. Results: Median ages for menarche, pubarche and telarche in our studied sample were: 11.9 ± 0.04; 11.13 ± 1.25 and 10.84 ± 1.34 years, respectively. A direct correlation was found between the age of menarche of adolescents and that of their mother (p p p = 0.001), but an indirect correlation was found with the girls’ hip circumference (p = 0.004). We demonstrated a clear secular tendency towards an earlier onset of menarche by comparing our results (11.9 ± 0.04) with data from 1985 (12.8 ± 1.3) for adolescents from the same city. Conclusion: We demonstrated a clear reduction in age at menarche of approximately 0.75 year/decade, higher than Tanner’s finding in 1962, but similar than that of Malina et al. in 2004.

Remoción de Semillas en Hábitats Transformados: Pogonomyrmex barbatus (Hymenoptera: Formicidae) y Cinco Especies de Cactáceas del Centro de México

One of the main consequences of human activities in semiarid zones is the transformation of habitats. In this work we studied the effect of this transformation on seed removal of five cacti species by the harvester ant Pogonomyrmex barbatus in the Tehuacán-Cuicatlán valley, a semiarid zone in central Mexico. Seed removal was quantified at three sites which have been under the effect of human activities: an abandoned crop field (CCA), a site with evidence of current human activities (TAH), and a site inside a botanic garden ( JB). We hypothesized that sites which have been under intense human activities would have low rates of seed removal because they offer harsh conditions for harvester ants, reducing their foraging activity. Results showed that vegetation and surface soil characteristics of the sites studied are affecting the rates of seed removal of the five cacti species studied. The lowest seed removal rate was found at CCA, the most transformed site. In contrast with our hypothesis the highest seed removal was found at TAH, the site which represents the intermediate transformation condition, because this site still conserves some characteristics which permit intense foraging activity by harvester ants. We also found that the seed removal rate varied among the different cacti species studied. Seed of E. chiotilla had the highest removal rate, whereas O. decumbens had the lowest. Differences in seed removal rate could be associated with the high heterogeneity found in sites with intermediate levels of transformation. Another factor that must be considered is the external morphology of seeds since smaller seeds presented highest removal rates.

Activity Patterns of a Harvester Ant in an Inter-tropical Semiarid Zone in Central Mexico

Red harvester ant (Pogonomyrmex barbatus) inhabits deserts of USA and Mexico. Its activity patterns are well known in temperate deserts, but they have not been studied in tropical ones. We studied these patterns in the Tehucan Valley, a tropical desert in central Mexico. It had bimodal activity patterns in spring, summer, and fall while unimodal patterns in winter. These patterns differ from those reported for this species in temperate deserts where activity stopped in winter. Our results suggest that P. barbatus extends its activity periods and remains active all year round in the Tehuacan Valley.

Foraging Activity and Trophic Spectrum of Red AntPogonomyrmex barbatusSmith, 1858, in Productivity-Contrasted Microenvironments

Foraging strategies can be influenced by many factors such as abundance, availability, and toxicity of the resources. In arid zones, the distribution and productivity of plants also act as additional factors that affect foraging strategies. Twenty colonies ofPogonomyrmex barbatusants were studied in an arid zone of central Mexico to evaluate the trophic niche breadth in two sites with contrasting productivities in terms of their diversity and amount of resources during two seasons. The results suggest that when the resources are abundant as in the rainy season, the trophic niche breadth is reduced in sites with high productivity and, in the same sites, the trophic niche breadth increases when the resources are limited as in the dry season. In contrast, the trophic niche breadth is similar in both conditions of resource availability (i.e., rainy and dry seasons) at sites with low productivity. During the dry season, populations ofP. barbatusshowed a similar foraging behavior in sites with high and low productivity. Thus, the particular characteristics of a site can significantly affect the foraging strategies of the ants in those environments.

PIXE analysis of Tillandsia usneoides for air pollution studies at an industrial zone in Central Mexico

In order to find out if there is a relation between atmospheric particulate matter composition and human health effects, metals and other elements measurement are performed. Analysis of atmospheric aerosols collected in filters is the usual method to achieve this task. Biological monitors provide an advantageous alternative way of sampling, since there is no need of special sampling devices, and accumulation time can be as long as desired. In this study, Tillandsia usneoides a reliable air pollution biological monitor that occurs naturally throughout Mexico was used to monitor air quality of Tula–Tepeji corridor at central Mexico. This area is considered critical zone because of atmosphere contaminants high concentration. Some biomonitors were transplanted from a clean environment to four sites at the Tula corridor. Plants samples were collected every two weeks from February to April 2008. PM 10 sampling in filters was also performed simultaneously at three locations where T. usneoides was transplanted, for a comparison. Chemical composition was determined by PIXE. Results showed that T. usneoides incorporates anthropogenic elements reaching maximal levels after 6 to 10 weeks approximately. Since results obtained with biomonitors agree with those obtained with aerosol filters, T. usneoides could be employed as a first approximation to provide insights of the atmospheric pollution level previous to a detailed study using filters.

Geographical distribution of genetic polymorphism of the pathogen Histoplasma capsulatum isolated from infected bats, captured in a central zone of Mexico

Fourteen Histoplasma capsulatum isolates recovered from infected bats captured in Mexican caves and two human H. capsulatum reference strains were analyzed using random amplification of polymorphic DNA PCR-based and partial DNA sequences of four genes. Cluster analysis of random amplification of polymorphic DNA-patterns revealed differences for two H. capsulatum isolates of one migratory bat Tadarida brasiliensis. Three groups were identified by distance and maximum-parsimony analyses of arf, H-anti, ole, and tub1 H. capsulatum genes. Group I included most isolates from infected bats and one clinical strain from central Mexico; group II included the two isolates from T. brasiliensis; the human G-217B reference strain from USA formed an independent group III. Isolates from group II showed diversity in relation to groups I and III, suggesting a different H. capsulatum population.

Physical effects of biological soil crusts on seed germination of two desert plants under laboratory conditions

We analyzed, under laboratory conditions, the physical effects of smooth and rugose soil crusts on the germination of Mimosa luisana (Leguminosae) and Myrtillocactus geometrizans (Cactaceae), two dominant species of plants in the Tehuacán Valley, a semiarid zone in central Mexico. In addition, effects of these crusts on the early seedling growth of M. geometrizans were also analyzed. Our results suggest that biological soil crusts have a positive effect on the seed germination of these plants. However, results about the effects of crusts on seedling growth showed no clear differences between treatments with and without crusts. More studies should be conducted, both in field and laboratory, to completely understand the factors that determine the effects of biological soil crusts on seed germination and seedling establishment of these plants.

Why is the Central Trans-Mexican Volcanic Belt (102°–99°W) in transtensive deformation?

Using well-defined focal mechanisms, new poles of rotation, and accurate bathymetry, it will be shown that the N34°E oblique convergence between the Cocos and North America plates, along the N290°E Middle American Trench, in front of Central Mexico (102°–99°W), is associated with slip partitioning. In the same way, it will be shown that the forearc sliver will move rigidly eastward along a trench parallel left-lateral strike-slip fault. By reviewing the literature and analysing seismicity, the E–W Central Trans-Mexican Volcanic Belt (TMVB) is the only active zone in Central Mexico. It is the best candidate to accommodate slip partitioning at the trench where mainly extensive E–W-trending normal active faults with left-lateral component are reported. Fault striae inversions, derived from the literature and our focal mechanisms inversion, confirm that the state of stress in the Central TMVB is transtensive since Middle Quaternary with Shmin ( σ 3) trending NW–SE and Shmax ( σ 1 or σ 2) trending NE–SW. The oblique convergence and slip partitioning at the trench induce this state of stress. The N290°W trench-parallel component, which should be accommodated in the upper plate, is, however, not parallel to the E–W arc-parallel component, but differs by about 20° clockwise. This implies that the former must be partitioned along the E–W faults of the Central TMVB. If we assume that the trench-parallel slip rate of 8 mm year −1 (102°–99°W) is fully accommodated along the Central TMVB, we should expect maximum horizontal extensional and left-lateral slip rates along E–W normal faults of 2 mm year −1 and less than 7 mm year −1, respectively. Strain partitioning may also be accommodated partially by the accretionary wedge or/and by normal faulting that affects the deeper part of the upper plate around 18°N of latitude.

Carboniferous to Cretaceous assembly and fragmentation of Mexico

The geologic framework of Mexico evolved through the Phanerozoic assembly and fragmentation of crustal elements derived from Laurentia, Gondwana, and an intra-Pacific volcanogenic terrane. In middle Paleozoic time, an inactive south-facing Laurentian continental margin of transform origin passed through northern Mexico to connect the miogeoclinal Cordilleran margin with the passive continental margin formed by Cambrian rifting in Texas. Gondwanan blocks of eastern Mexico were accreted to Laurentia by juxtaposition along the Ouachita-Marathon suture belt in earliest Permian time. Subsequent Jurassic opening of the Gulf of Mexico by seafloor spreading displaced the Yucatan-Chiapas block southward, as it rotated anticlockwise from edge-driven shear between Colombia and Florida, along a gulf-flank transform passing through the Isthmus of Tehuantepec. The continuity of a linear north-trending Permian–Triassic arc (now represented by a granite belt) in eastern Mexico precludes strike-slip slivering of Mexico during gulf opening and implies that Colombia lay east of internally coherent Gondwanan crust of southeastern Mexico, but south of Yucatan-Chiapas, prior to Pangean breakup. During subsequent intracontinental rifting, crustal elements of eastern Mexico were displaced southeastward, along a transform between basement blocks of present northeastern and east-central Mexico, in the wake of Colombia9s retreat from Laurentia. The Chortis block of nuclear Central America also lay within Pangea west of Colombia and remained attached to southern Mexico prior to its Cenozoic displacement eastward along the Cayman transform. The Caborca block of northwestern Mexico was displaced southeastward from the Cordilleran miogeocline by Permian–Triassic slip along a transform that linked the convergent Sonoma orogen with the northern end of a subduction zone in central Mexico that paralleled the Permian–Triassic magmatic arc built on Gondwanan crust of eastern Mexico. Subsequent post–Middle Triassic initiation of a west-facing continental-margin arc-trench system (i.e., with the subducting slab moving down to the east) along the structurally modified paleo–Pacific flank of Pangea produced middle Mesozoic arc assemblages extending southeastward from California and Arizona through east-central Mexico into Colombia. Beyond a compound suture belt lying outboard of the middle Mesozoic continental margin, western Mexico is underlain by Mesozoic volcanogenic crust formed beneath an east-facing intraoceanic island arc that was accreted to Laurentian and Gondwanan Mexico by arc-continent collision late in Early Cretaceous time. The accreted arc assemblage was overlapped by late Early Cretaceous–early Late Cretaceous carbonate platforms linked depositionally with comparable facies in eastern Mexico. As the offshore island arc approached the continent, progressive consumption of the intervening oceanic plate induced slab rollback beneath the Jurassic magmatic arc on the mainland, terminating arc magmatism and promoting development of associated rift troughs that extend from northeastern Mexico to southeastern California. Following arc collision and accretion, reversal of subduction polarity along the expanded western flank of Mexico created a west-facing continental-margin arc- trench system that was continuous with the Cordilleran arc and Franciscan trench of California. Subsequent subduction produced volcanic-plutonic arc assemblages on the mainland and in Baja California, which was contiguous with the mainland prior to Neogene seafloor spreading that opened the Gulf of California. A paired late Early Cretaceous subduction complex and late Mesozoic forearc basin occurred along the Pacific flank of Baja California.