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Arceo S.D.,Laboratorio Of Genetica | Martinez-Tabche L.,Laboratorio Of Toxicologia Acuatica | Alvarez-Gonzalez I.,Laboratorio Of Genetica | Lopez E.L.,Laboratorio Of Bioconservacion Y Manejo | Madrigal-Bujaidar E.,Laboratorio Of Genetica
Revista de Biologia Tropical | Year: 2015

The toxicity induced by insecticides in aquatic organisms is of utmost relevance because it may give a clue about the degree of health or damage of the involved ecosystem. In the present report, we determined the effect of dieldrin (DD) and chlorpyrifos (CP) on the freshwater crayfish, Cambarellus montezumae. The organisms (4-6cm in diameter) were collected in the Ignacio Ramírez Reservoir, situated at 50km Northeast of Mexico City, in the Rio Lerma Basin. Initially, we determined the LC50 value with the Probit method, then the DNA damage with single cell gel electrophoresis (comet assay applied at 24, 48, and 72h of exposure) to the brain and hepatopancreas of animals exposed (in reconstituted water) to 0.05 and 0.5mg/L of each insecticide. In the hepatopancreas of the same organisms, we determined the lipid peroxidation by applying the TBARS test. DNA damage and lipid peroxidation were also evaluated with the same methods to organisms exposed in water from the reservoir. In regard to the LC50, at 72h of exposure, we found a value of 5.1mg/L and a value of 5.62mg/L for DD and CP, respectively. The comet assay applied at different exposure times showed significant DNA damage to both organs, with respect to the control level. In the case of DD, statistical significance was observed for the two doses in the whole evaluated schedule. CP was genotoxic in the brain with the high dose at 72h, and in the hepatopancreas with the two tested doses at all evaluated exposure times. Also, a significant lipid peroxidation increase was detected with the two doses of insecticides. In the study with water from the reservoir, a more pronounced DNA damage was detected. Our results showed strong DNA damage induced by both insecticides in the crayfish, as well as a correlation with the lipid peroxidation effect, suggesting that oxida-tive stress is involved in the genotoxic alteration. Our results also showed the usefulness of the studied organism as well as the applied tests for the evaluation of toxicological effects, and suggested the pertinence of applying the comet assay to other freshwater organisms to evaluate the bioaccumulation of insecticides. © 2015, Universidad de Costa Rica. All Rights Reserved.

Real-Monroy M.D.,Laboratorio Of Bioconservacion Y Manejo | Martinez-Mendez N.,Laboratorio Of Bioconservacion Y Manejo | Ortega J.,Laboratorio Of Bioconservacion Y Manejo
Acta Chiropterologica | Year: 2014

Major Histocompatibility Complex (MHC) encodes a group of closely linked genes that play a central role in the vertebrate immune system, those are crucial for understanding the influence of natural selection on genetic diversity in wild populations. We examined genetic variation at the MHC class II DRB gene in 15 sampled localities of the Jamaican fruit-eating bat (Artibeus jamaicensis) in Mexico. Artibeus jamaicensis is one of the most abundant and widely distributed species in the Neotropics, and is therefore an excellent species in which to examine immunological gene variation. Using PCR amplifications, cloning and sequencing, we assessed individual DRB allelic diversity. Sequences from 193 individuals were analyzed and no deletions or insertions were detected, thus likely representing functional alleles. We identified 161 alleles (allele diversity = 0.9789 + 0.0022), with three to five alleles per individual, suggesting gene duplication events. Our results suggest the presence of recombination involved with generating DRB diversity in A. jamaicensis; we detected one recombination breakpoint and one recombination event. In the antigen-binding site (ABS), the average number of nonsynonymous substitutions per site is greater than the synonymous substitutions per site (0.7033 versus 0.2966, respectively) providing evidence for positive selection acting above the evolutionary history of the species in shaping MHC diversity. © Museum and Institute of Zoology PAS.

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