Conkal Institute of Technology
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Ruiz-Sanchez E.,University of Toronto | Ruiz-Sanchez E.,Conkal Institute of Technology | Lange A.B.,University of Toronto | Orchard I.,University of Toronto
Toxicon | Year: 2010

Destruxins, a family of cyclic peptides, are produced by various species of entomopathogenic fungi. These peptides have been shown to influence calcium-dependent processes in insect cell lines and tissues, such as skeletal muscles. To better understand the mechanism of action of these peptide toxins on insect muscular tissues, we have evaluated the effects of destruxin A on the contractions of oviducts and hindgut of Locusta migratoria. In oviducts, destruxin A increased the frequency of spontaneous contractions and induced a dose-dependent tonic contraction; the EC50 for lower lateral and upper lateral oviducts was 0.7 μM and 8.7 μM, respectively. In hindgut, destruxin A also caused an increase in the frequency of spontaneous contractions; the EC50 was 3.2 μM. The action of destruxin A was abolished in Ca2+-free saline or when the Ca2+ channel blocker CoCl2 was added to the incubation saline. Likewise, the presence of 50 μM nifedipine or 100 μM verapamil in the medium reduced the magnitude of destruxin A's effect, particularly in hindgut. The depolarization of muscle membranes by 100 mM K+ saline prevented the action of destruxin A. Preincubation of lower lateral oviducts in the intracellular Ca2+ antagonist TMB-8 did not have any effect on destruxin A action; however, preincubation in the calmodulin inhibitor trifluoperazine greatly reduced the effect of destruxin A. Taken together, these results show that destruxin A has an excitatory effect on contractions of insect visceral muscles of L. migratoria. Destruxin A-induced contractions appear to be dependent on extracellular, but not on intracellularly-released Ca2+, which suggest that this peptide toxin might be acting on insect visceral muscle by facilitating an influx of extracellular Ca2+. © 2010 Elsevier Ltd.

Bordera S.,University of Alicante | Gonzalez-Moreno A.,Conkal Institute of Technology
Canadian Entomologist | Year: 2015

The New World fauna of the genus Oxytorus Förster, 1869 (Hymenoptera: Ichneumonidae) comprises 11 species, two of them, O. bahiensis new species and O. sinopae new species, both from eastern Brazil, are described as new. New data about distribution and variation of several species are reported. Oxytorus peruvianus Alvarado, Bordera, and Rodríguez-Berrío, 2011 is reported for the first time from Brazil and Ecuador, and O. alfredi Gauld and Mallet, 2000 from Guatemala, Mexico, and Trinidad and Tobago. An illustrated key to the New World species of Oxytorus is provided. © Entomological Society of Canada 2014.

Quezada-Euan J.J.G.,Autonomous University of Yucatán | Lopez-Velasco A.,Autonomous University of Yucatán | Perez-Balam J.,Autonomous University of Yucatán | Moo-Valle H.,Autonomous University of Yucatán | And 2 more authors.
Insectes Sociaux | Year: 2011

Although variation in body size has been recently reported in stingless bees (Meliponini), empirical evidence evaluating possible factors related to such variation is lacking, and thus it is not clear if it may have an adaptive significance. We evaluated if variation in the body size and weight of workers of stingless bees fluctuates across a seasonal pattern and if this could be related to characteristics of the food consumed during the larval stage. The weight of larval provisions, their protein, and sugar content were evaluated in four colonies of Nannotrigona perilampoides every 2 months across 1 year. Worker-destined larvae from the same combs were allowed to develop and were sampled as callow workers to determine their weight and size using morphometric data. The weight and size of workers were highly correlated and varied across the seasons in established colonies, suggesting that size variation cycles across the year in stingless bees. An increase in the protein content and, to a lesser degree, the quantity of larval food were positively linked to variation in body weight and size; food with richer protein content resulted in larger and heavier workers. This study provides the first evidence of an effect of the quantity and composition of larval food on the size of workers in stingless bees. Although body weight and size of workers differed across seasons, they were not readily noticeable as changes seem to occur as a continuum across the year. Since size polymorphism was of a larger magnitude across time but not within age cohorts and as it was highly determined by food resources, it may not be an adaptive feature in stingless bees. However, more studies are needed to determine the role of the cyclical change in worker body size on colony performance and thus its adaptive significance in stingless bees. © 2010 International Union for the Study of Social Insects (IUSSI).

Ruiz-Sanchez E.,Conkal Institute of Technology | O'Donnell M.J.,McMaster University | Donini A.,York University
Journal of Insect Physiology | Year: 2015

The Malpighian (renal) tubules play important roles in ionic and osmotic homeostasis in insects. In Lepidoptera, the Malpighian tubules are structurally regionalized and the concentration of Na+ and K+ in the secreted fluid varies depending on the segment of tubule analyzed. In this work, we have characterized fluid and ion (Na+, K+, H+) transport by tubules of the larval stage of the cabbage looper Trichoplusia ni; we have also evaluated the effects of fluid secretion inhibitors and stimulants on fluid and ion transport. Ramsay assays showed that fluid was secreted by the iliac plexus but not by the yellow and white regions of the tubule. K+ and Na+ were secreted by the distal iliac plexus (DIP) and K+ was reabsorbed in downstream regions. The fluid secretion rate decreased > 50% after 25μM bafilomycin A1, 500μM amiloride or 50μM bumetanide was added to the bath. The concentration of K+ in the secreted fluid did not change, whereas the concentration of Na+ in the secreted fluid decreased significantly when tubules were exposed to bafilomycin A1 or amiloride. Addition of 500μM cAMP or 1μM 5-HT to the bath stimulated fluid secretion and resulted in a decrease in K+ concentration in the secreted fluid. An increase in Na+ concentration in the secreted fluid was observed only in cAMP-stimulated tubules. Secreted fluid pH and the transepithelial electrical potential (TEP) did not change when tubules were stimulated. Taken together, our results show that the secretion of fluid is carried out by the upper regions (DIP) in T. ni Malpighian tubules. Upper regions of the tubules secrete K+, whereas lower regions reabsorb it. Stimulation of fluid secretion is correlated with a decrease in the K+/Na+ ratio. © 2015 Elsevier Ltd.

Andueza-Noh R.H.,Conkal Institute of Technology | Martinez-Castillo J.,Research Center Cientifica Of Yucatan | Chacon-Sanchez M.I.,National University of Colombia
Genetica | Year: 2015

Previous studies have suggested that the Mesoamerican small-seeded landraces of Lima bean may have been domesticated more than once in Mesoamerica, once in central-western Mexico and another one in an area between Guatemala and Costa Rica. However, these findings were based on sequencing of only one locus from nuclear DNA, and additional confirmation was needed. Here we contribute with additional data on the origin of the Mesoamerican landraces and document the founder effect due to domestication. We characterized 62 domesticated, 87 wild and six weedy Lima bean accessions with ten microsatellite loci. Genetic relationships were analyzed using genetic distances and Bayesian clustering approaches. Domestication bottlenecks were documented using inter-population comparisons and M ratios. The results support at least one domestication event in the area of distribution of gene pool MI in central-western Mexico and also show that some landraces are genetically related to wild accessions of gene pool MII. Also, our data support founder effects due to domestication in Mesoamerican Lima bean landraces. Although we could not establish more specifically the place of origin of the Mesoamerican Lima bean landraces, our results show that these are not a genetically homogeneous group, a finding that may be compatible with a scenario of more than one domestication event accompanied by gene flow. The complex genetic makeup of landraces that we found indicates that a more comprehensive geographic and genomic sampling is needed in order to establish how domestication processes and gene flow have shaped the current genetic structure of landraces. © 2015, Springer International Publishing Switzerland.

Gonzalez-Moreno A.,Conkal Institute of Technology | Bordera S.,University of Alicante | Delfin-Gonzalez H.,Autonomous University of Yucatán
Journal of Insect Conservation | Year: 2015

Currently efforts for conservation have been globally increasing, with the declaration of Protected Natural Areas. However, these efforts are usually focused on mammal, bird or plant species, but there is a considerable lack of data in regard to insect fauna in most of the world’s reserves. In order to redress the balance, the aim of this work was to assess spatial and temporal diversity of Cryptinae, one of the most species-rich subfamily of hymenopteran parasitoids, in a Protected Natural Area in Mexico. The sampling program was conducted using Malaise traps, which were functioning throughout 2008–2009, in three vegetation types of Ría Lagartos Biosfere Reserve (Mexico). A total of 108 species were found. Rarefaction showed that there are no differences in species richness between vegetation types, but there are significant seasonal changes, being most specious in the rainy season. Regarding abundance, this was significantly affected by vegetation and season. Related to community structure, Agonocryptus chichimecus, Camera euryaspis, and Acerastesmyartsevae were the dominating species in the assemblages. Dry forest and rainy season showed highest diversity and evenness. β-Diversity between vegetation types and season was high; the complementarity value reaches 82.4 and 77.7 % respectively. Spatial and temporal diversity partitions show that diversity had more changes related to vegetation types than to seasons. Diversity was strongly influenced by β-diversity between vegetation types and by β-diversity among months and among seasons, with a contribution to the total species richness with 49.4, 19.4 and 14.5 %, respectively. © 2015, Springer International Publishing Switzerland.

Ruiz-Sanchez E.,Conkal Institute of Technology | O'Donnell M.J.,McMaster University
Current Opinion in Insect Science | Year: 2015

The insect excretory system plays essential roles in osmoregulation, ionoregulation and toxin elimination. Understanding the mechanisms of fluid and ion transport by the epithelial cells of the excretory system provides a foundation for development of novel pest management strategies. In the present review, we focus on two such strategies: first, impairment of osmoregulation by manipulation of diuretic or antidiuretic signaling pathways and second, interference with toxin elimination by inhibition of toxin transport systems. ©Elsevier Inc.All rights reserved.

Michel-Lopez C.Y.,Autonomous University of Baja California | Gonzalez-Mendoza D.,Autonomous University of Baja California | Ruiz-Sanchez E.,Conkal Institute of Technology | Zamora-Bustillos R.,Conkal Institute of Technology
Chemistry and Ecology | Year: 2014

The effects of copper (Cu2+) on photochemical efficiency, cellular viability and total phenolic content in Prosopis glandulosa leaves were evaluated after 4, 8 or 12 h exposure to 0.1, 10 or 100 mM Cu2+ using the tissue tolerance test. The results showed that significant reductions (p<0.003) of photochemical efficiency in P. glandulosa leaves were found after 8 h exposure to 100 mM Cu2+ compared with controls leaves. The results also showed a significant increase (p<0.05) on electrolyte leakage values in P. glandulosa leaves after 4 h exposure to 100 mM Cu2+ compared with control leaves. Total phenolic content in P. glandulosa leaves only differed significantly when exposed 12 h to the highest concentration of Cu2+. These results suggest that Cu2+ can produce reactive oxygen species that may form hydroxyl radicals that damage proteins and lipids, which in turn causes loss of integrity and reduce photochemical efficiency of leaves. In conclusion, the photochemical efficiency and cellular viability analyses can be used as useful physiological tools to assess early changes in photosynthetic performance of P. glandulosa in response to copper pollution. © 2013 © 2013 Taylor & Francis.

Cruz-Estrada A.,Research Center Cientifica Of Yucatan | Gamboa-Angulo M.,Research Center Cientifica Of Yucatan | Borges-Argaez R.,Research Center Cientifica Of Yucatan | Ruiz-Sanchez E.,Conkal Institute of Technology
Electronic Journal of Biotechnology | Year: 2013

Background: The whitefly (Bemisia tabaci Genn.) is a widely distributed and highly harmful plant pest species. The management of B. tabaci has been typically carried out by chemical pesticides. In the last decade however, there has been an increasing interest in natural products, particularly those of plant origin, to control this pest species. In the present work, aqueous and ethanolic extracts of native plants from the flora of the Yucatán peninsula (Acalypha gaumeri, Annona squamosa, Carlowrightia myriantha, Petiveria alliaceae and Trichilia arborea) and the introduced plant Azadirachta indica were collected and evaluated for insecticidal activity against eggs and nymphs Bemisia tabaci. Results: Most of the aqueous and ethanolic extracts showed high insecticidal effects on B. tabaci eggs. The lowest LC50 values were recorded in the aqueous extracts of A. gaumeri (0.39% w/v), A. squamosa (0.36% w/v), P. alliaceae (0.42% w/v) and A. indica (0.30% /v), as well as in the ethanolic extracts of P. alliaceae (2.09 mg mL-1) and T. arborea (2.14 mg mL-1). On the other hand, B. tabaci nymphs were not affected by the aqueous extracts, but were highly sensitive to the ethanolic extracts of the tested plants. The lowest LC50 values were recorded in the ethanolic extracts of P. alliaceae (1.27 mg ml-1) and T. arborea (1.61 mg mL-1). The GC-MS analysis showed that phytol was the major component of the ethanolic extract of P. alliaceae and fatty acids were the major components of ethanolic extract of T. arborea. Conclusions: Overall, results suggest that ethanolic extracts of P. alliaceae and T. arborea leaves showed the highest insecticidal effects on eggs and nymphs B. tabaci. The extracts from P. alliaceae and T. arborea are good candidates to be developed as sources of natural insecticides for the management of immature B. tabaci since their effects were comparable with that showed by the extracts of A. indica, a well-known plant species for its insecticidal activity. © 2013 by Pontificia Universidad Católica de Valparaíso, Chile.

Ugalde J.R.,Conkal Institute of Technology
Cuban Journal of Agricultural Science | Year: 2014

The reproductive biotechnology includes techniques designed to produce and preserve the domestic animals and those that are in danger of extinction or already extinct. The purpose of this study is to make a brief review about the evolution of the reproductive biotechnology and the possibility of its application and development in an immediate future.

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