Recurso polínico y ciclo estacional de Thygater aethiops (Hymenoptera: Apidae) en un ambiente urbano (Bogotá-Colombia) / Pollen resource and seasonal cycle of Thygater aethiops (Hymenoptera: Apidae) in an urban environment (Bogotá-Colombia)

ResumenThygater aethiops es una abeja nativa que puede encontrarse en parques y jardines en diversas áreas urbanas como aquellas de la ciudad de Bogotá (Colombia). Sin embargo, es poco lo que se conoce sobre su biología y sus adaptaciones ecológicas a áreas urbanas. El presente estudio tuvo como objetivos describir ciclos estacionales y la actividad de forrajeo diaria de T. aethiops, así como identificar el recurso polínico usado por estas abejas a lo largo de un año en una población que nidifica en un agregado en el "Parque Nacional Enrique Olaya Herrera" de Bogotá. Cambios en la actividad de nidificación fueron registrados semanalmente contando el número de nidos activos en el agregado entre diciembre/2012 y febrero/2014. Para determinar el horario de forrajeo diario, se contó el número de abejas que entraban a sus nidos en un periodo de 10 minutos cada hora entre las 8:00 y las 14:00 h. Semanalmente se capturaron hembras que estuvieran regresando a sus nidos con cargas de polen, entre septiembre/2012 y agosto/2013; dichas cargas fueron analizadas. Se observó tres picos de nidificación tras los picos de precipitación, pero el número de nidos activos no estuvo correlacionado con la precipitación. El número de nidos activos se redujo (20-50 % de los nidos) después de que se registrara un disturbio antrópico en el área de nidificación. Las abejas forrajean por polen y néctar entre las 8:00 y 14:00 h con un pico de actividad a las 10:00 h. La actividad de forrajeo diaria cambió durante el periodo de estudio debido a disturbios antrópicos. No hubo una relación significativa entre la temperatura del aire y el número de entradas a los nidos. El horario de actividad no cambió entre los periodos secos y lluviosos. Se encontró un total de 26 tipos polínicos en 169 cargas de polen. Ulex europaeus (Fabaceae) y Solanum laxum (Solanaceae) fueron las plantas más abundantes representadas en las cargas de polen durante todo el periodo de estudio. De acuerdo a estos resultados, T. aethios sería considerada una especie mesoléctica. La habilidad de T. aethiops para utilizar diferentes recursos polínicos tanto nativos como introducidos, así como su presumible capacidad para recuperar su población después de disturbios son características que le pueden haber permitido adaptarse a ambientes urbanos. El conocimiento de los recursos florales, así como otras características biológicas de esta abeja son importantes para promover su conservación en áreas urbanas.

Abstract:Thygater aethiops is a native bee that can be found in parks and gardens in diverse urban areas such as those in the city of Bogotá (Colombia). However, little is known about its biology as well as ecological adaptations to urban areas. This study aimed to describe the seasonal cycle and daily foraging activities of T. aethiops, as well as identify the pollen resources used by this bee over a year in a population nesting in an aggregation in the "Parque Nacional Enrique Olaya Herrera" in Bogotá. Changes in the nest activity were monitored weekly by counting the number of active nests in the aggregation between December/2012 and February/2014. To determine the daily foraging activity, the numbers of bees entering their nests over a period of 10 minutes every hour between 8:00 and 14:00 h were recorded. Females with pollen loads entering to their nest were captured weekly, between September/2012 and August/2013, and their pollen loads analyzed. Three nesting peaks occurred after the precipitation peaks, but the number of active nests was not correlated with precipitation. The nesting activities stopped in a large number of the active nests (20-50 % of nests) after an anthropic disturbance was registered in the nesting area. Bees forage for nectar and pollen between 8:00 and 14:00 h, with a peak at 10:00 h. Daily foraging activity changed during the study period due to anthropic disturbance. There was not a significant relationship between air temperature and the number of females entering their nests. Foraging activities did not change between the dry and rainy seasons. A total of 26 pollen types were found in 169 pollen loads. Ulex europaeus (Fabaceae) and Solanum laxum (Solanaceae) were the most abundant plants represented on the pollen load across the study period. According to these results, T. aethiops would be considered a mesolectic species. The ability of T. aethiops to use different pollen resources both native and exotic, as well as to presumably recover its population after disturbances, are characteristics that may have allowed this bee to adapt to urban environments. Knowledge on the floral resources as well as other biological features of this bee species is important to promote its conservation in urban areas. Rev. Biol. Trop. 64 (3): 1247-1257. Epub 2016 September 01.

Callus induction and plant regeneration of Ulex europaeus

A callus induction and plant regeneration protocol was developed from leaf and thorn explants for the plant Ulex europaeus. Explants were incubated on 2 percent sucrose half-strength Murashige and Skoog Medium (MS) with various combinations of plant growth regulators and antioxidants. The best frequency of callus and shoot formation was obtained with 2,4-dichlorophenoxyacetic acid (2,4-D) 1 mg/l x kinetin (Kin) 0.2 mg/l (DK Medium; callus induction) and zeatin (Z) 1 mg/l (DK medium; shoot induction). Both media were supplemented with ascorbic acid 200 mg/l to prevent browning and death of the explants. The regenerated shoots transferred to rooting medium (half-strength MS Medium, 2 percent sucrose) showed rapid growth and development of roots (100 percent). Rooted plantlets were successfully transferred to soil in pots containing a 3:1 mixture of soil and vermiculite.

EVALUACIÓN DE LA REGENERACION DE Acacia decurrens, Acacia melanoxylon Y Ulex europaeus EN ÁREAS EN PROCESO DE RESTAURACIÓN ECOLÓGICA / EVALUATION OF REGENERATION OF Acacia decurrens, Acacia melanoxylon AND Ulex europaeus IN AREAS IN PROCESS OF ECOLOGICAL RESTORATION

Se evaluó la regeneración de Acacia decurrens, Acacia melanoxylon y Ulex europaeus, en una zona sujeta a un proceso de restauaración ecológica. En las áreas con presencia de individuos arboreos de Acacia decurrens y Acacia melanoxylon se presenta expresión del banco de semillas con formación periódica de la capa de hojarasca que detiene o desvía el proceso sucesional. En las áreas de claro se presenta regeneración de Ulex europaeus, ocupando rápidamente los espacios libres de vegetación. La plantación de especies nativas de porte arbustivo y arbóreo, junto con el control periódico de la regeneración y formación de hojarasca de las especies tensionantes, facilita la activación de los mecanismos de sucesión secundaria, aumentando la riqueza, diversidad y equitatividad de las especies en el ecosistema.

Regeneration of Acacia decurrens, Acacia melanoxylon and Ulex europaeus In an area subject to the process of ecological restoration was evaluated. In areas with Acacia decurrens and Acacia melanoxylon arboreal individuals expression of seed banks with periodic accumulation of fallen leaves that stop or divert the succession process is present. In open areas Ulex europaeus regeneration occurs quickly occupying areas without vegetation. The plantation of native shrubby or arboreal species, along with periodic monitoring of the regeneration and fallen leaves formation of alien species, facilitate the activation of secondary succesion mechanisms, increasing the richness, diversity and evenness of species in the ecosystem.

Sequential Changes in Aberrant Crypt Foci and Lectin Expression in the Early and Late Stages of DMH-Induced Colon Carcinogenesis in Rats

BACKGROUND/AIMS: The purpose of this study was to investigate the malignant potential of aberrant crypt foci (ACF) by measuring the multiplicity of crypts and lectin expression in the early and late stages of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. METHODS: Six-week-old Wistar rats were injected subcutaneously with DMH for 27 weeks. We classified ACF according to the number of crypts per ACF as a few crypts ( or =4 crypts, NC ACF). Immunohistochemistry was used to evaluate lectin expression. RESULTS: In the early stage, FC ACF (590/1,902, 31.0%) occurred more frequently than NC ACF (35/449, 7.8%); whereas in the late stage, NC ACF (176/449, 39.2%) occurred more frequently than FC ACF (324/1,902, 17.0%). The number of ACF peaked at 15 to 20 weeks. The ratio of NC/FC ACF increased gradually during carcinogenesis. The expression of both UEA1 and PNA was higher in NC ACF than FC ACF. Lectin expression increased in the late stage compared with the early stage. CONCLUSIONS: The expression of lectin was higher in NC ACF and ACF in the late stage. Therefore, ACF with higher multiplicities in the late stage may have more malignant potential in DMH-induced colon carcinogenesis.

Isolation and pure culture of microvascular endothelial cells from the fetal skin

Microvascular endothelial cells were purely isolated from human fetal skin using magnetic particles. The principle of this technique is based on the selective binding of the lectin Ulex europaeus I (UEA I) to the endothelial cell surface via fucose residues. Initially UEA I was covalently bound to tosyl-activated magnetic polydisperse polymer particles (Dynabeads) and then the UEA I-coated beads were collected using a magnetic particle concentrator (MPC). Endothelial cells were isolated by extracting microvascular segments from trypsin-treated fetal skin tissue and were purified by sieving with nylon mesh and by 35% Percoll gradient centrifugation. For further purification, the obtained cells were incubated with UEA I-coated Dynabeads. The endothelial cells bound to the Dynabeads were collected using MPC. This is a simple and reproducible technique for isolating a pure population of microvascular endothelium from the fetal skin.