Thermal stress induces pyknosis in pigeon erythrocytes: digital image analysis.

Pyknosis or hypercondensation of chromatin is informative in the understanding of nucleosomal packing in translationally inactive chromatin and in the compression of cell death. However, mechanisms that result in the formation of avian erythrocytes with variant nuclear morphology are poorly understood.Purpose: In this work, we evaluated pyknosis in pigeon erythrocytes treated with thermal stress using Digital Image Analysis (DIA).Materials and methods: Pigeon erythrocytes were treated at thermal stress (33 °C, 43 °C, and 53 °C), and nuclear modifications were analyzed by DIA.Results: Our results showed that thermal stress induced DNA condensation. Based on DNA fluorescent staining and compaction, four subclasses with progressively more pyknotic nuclei each could be distinguished. Alkaline comet assay showed that the presence of pyknotic nuclei was associated with the DNA fragmentation typical of apoptosis. DIA analysis showed a decrease of nuclear area and a significant increase of fluorescence intensity with respect to non-pyknotic nucleus. Additionally we observed nuclear dissolution events associated with swell and loose membrane integrity.Conclusion: These findings can contribute to the evaluation of health and metabolic status in diagnostic cytology, especially in neoplastic conditions and infection by microorganisms.

Evaluation of environmental genotoxicity by comet assay in Columba livia.

The concentrations of recognized or suspected genotoxic and carcinogenic agents found in the air of large cities and, in particular, developing countries, have raised concerns about the potential for chronic health effects in the populations exposed to them. The biomonitoring of environmental genotoxicity requires the selection of representative organisms as "sentinels," as well as the development of suitable and sensitive assays, such as those aimed at assessing DNA damage. The aim of this study was to evaluate DNA damage levels in erythrocytes from Columba livia living in the metropolitan area of Monterrey, Mexico, compared with control animals via comet assay, and to confirm the results via Micronuclei test (MN) and DNA breakage detection-fluorescence in situ hybridization (DBD-FISH). Our results showed a significant increase in DNA migration in animals from the area assayed compared with that observed in control animals sampled in non-contaminated areas. These results were confirmed by MN test and DBD-FISH. In conclusion, these observations confirm that the examination of erythrocytes from Columba livia via alkaline comet assay provides a sensitive and reliable end point for the detection of environmental genotoxicants.

Hábitos alimenticios y dieta invernal de Charadrius melodus (Charadriiformes: Charadriidae) en Boca Ciega, Tamaulipas, México / Food habits and winter diet of Charadrius melodus (Charadriiformes: Charadriidae) in Boca Ciega, Tamaulipas, Mexico

The Piping Plover (Charadrius melodus) is a migratory endangered species that arrives, along with a great number of other winter migratory birds, to Boca Ciega every year. In spite of the importance of this ecosystem, these species, are threatened by the current habitat change caused by the dredging activities in the area. With the aim to generate new information about the importance of this area during winter, we studied C. melodus activities during the winter season in Laguna Madre, from December 2009 to March 2010. Our objectives were: 1) determine the importance of the area during winter, 2) describe C. melodus ethology, feeding substrate preferences and food items, 3) to analyze and describe the sympatric diversity associated with C. melodus. A total of ninety nine individuals were observed during the monitoring. The Cochran and Kendall test showed a high significance of the species with the substrate and signs tests using a binomial distribution that indicated a high preference for algal type of substrate. The highest activity recorded for this species during this winter season was feeding. The principal food items found in sediments were larvae of Diptera: Chironomidae and Ephydridae. The sympatric species of C. melodus were two families of Charadriiforms: Scolopacidae (nine species) and Charadriidae (two species). We concluded that this is an important area for feeding, protection and rest sites for this species, and its protection and management is recommended.

Charadrius melodus es una especie migratoria en peligro de extinción. Cada año, la Laguna Madre recibe aves migratorias invernales, incluyendo a la especie antes mencionada, sin embargo su estabilidad se encuentra amenazada por el cambio de hábitat ocasionado por el dragado que se está realizando en la zona. La falta de estudios sobre C. melodus durante el invierno en la Laguna Madre, motivó la realización del trabajo (diciembre 2009-marzo 2010). Los objetivos fueron: 1) determinar la importancia del área invernal, 2) describir la etología y preferencias de sustrato en la alimentación, 3) analizar ítems alimenticios potenciales y describir la diversidad simpátrica asociadas a C. melodus. Se observaron 99 individuos durante el muestreo. Las pruebas de Cochran y Kendall presentaron una alta significancia de la especie con un tipo de sustrato y las pruebas de signos utilizando una distribución binomial indicaron que existe una alta preferencia hacia un tipo de sustrato. La mayor actividad registrada durante el periodo de muestreo fue la de alimentación. Los recursos alimenticios encontrados en las muestras de sedimentos fueron larvas de Dípteros. Las especies simpátricas a C. melodus pertenecen al orden Charadriiformes con dos familias: Charadriidae nueve especies y Scolopacidae dos especies. Por la importancia de la zona, se recomienda proteger Boca Ciega, pues representa sitios de alimentación, protección y descanso para el Chorlo melódico.