Maria Luiza Videira Marceliano

Number and distribution of neurons in the retinal ganglion cell layer in relation to foraging behaviors of tyrant flycatchers.

The tyrant flycatchers represent a monophyletic radiation of predominantly insectivorous passerine birds that exhibit a plethora of stereotyped prey capture techniques. However, little is known about their retinal organization. Using retinal wholemounts, we estimated the total number and topography of neurons in the ganglion cell layer in the generalist yellow‐bellied elaenia (Elaenia flavogaster) and the up‐hover‐gleaner mouse‐colored tyrannulet (Phaeomyias murina) with the optical fractionator method. The mean estimated total number of neurons in the ganglion cell layer was 4,152,416 ± 189,310 in E. flavogaster and 2,965,132 ± 354,359 in P. murina. Topographic maps of isocounting lines revealed a similar distribution for both species: a central fovea and a temporal area surrounded by a poorly defined horizontal streak. In addition, both species had increased numbers of giant ganglion cells in the dorsotemporal retina forming an area giganto cellularis. In E. flavogaster, these giant ganglion cells were also distributed across the nasal and ventral retinal peripheries, which is in agreement with the generalist habits of this species. However, in P. murina these cells were rarely seen along the nasal and ventral peripheries, possibly reflecting a lesser need to perceive movement because this species captures stationary insects resting on foliage. Thus, we suggest that the retinas of the tyrant flycatchers in the present study show a general common pattern of neuron distribution in the ganglion cell layer irrespective of their foraging habits. We also suggest that the distribution of giant ganglion cells is indicative of the visual requirements of the species. J. Comp. Neurol. 514:66–73, 2009.

The Retina of Tyrant Flycatchers: Topographic Organization of Neuronal Density and Size in the Ganglion Cell Layer of the Great Kiskadee Pitangus sulphuratus and the Rusty Margined Flycatcher Myiozetetes cayanensis (Aves: Tyrannidae)

Tyrant flycatchers comprise the largest group of passerine birds of the Neotropical region but their retinal organization is unknown. The great kiskadee, Pitangus sulphuratus, is categorized as a supreme generalist and utilizes a variety of foraging strategies. The rusty margined flycatcher, Myiozetetes cayanensis, is partially frugivorous and captures insects in the air. Using retinal wholemounts, we described the topographic distribution of density and size of neurons lying in the retinal ganglion cell layer in those two species of tyrant flycatchers. Maps of neuron distribution showing isodensity contours revealed the presence of a pronounced central fovea and a temporal area in both species. Both retinal specializations were circumscribed by an inconspicuous horizontal visual streak. The highest foveal densities ranged from 48,000 to 55,000 cells/mm2 for Pitangus sulphuratus and between 62,000 and 65,000 cells/mm2 for Myiozetetes cayanensis. The peak density in the temporal area was around 40,000 cells/mm2 for Pitangus sulphuratus and 46,000 cells/mm2 for Myiozetetes cayanensis. At central, mid-peripheral and peripheral eccentricities, perikaryon size varied quite similarly in both species. A cohort of giant retinal ganglion cells with perikaryon size > 300 µm2 was observed at the temporal periphery and defines an ‘area giganto cellularis’ described previously in procellariiform seabirds. This specialization is thought to be involved in movement detection and could aid the tyrant flycatchers to capture moving prey. Functionally, the presence of a fovea associated with a temporal area would allow high spatial resolution for capturing insects by the tyrant flycatchers. Nonetheless, even though both species exhibit different foraging strategies, they shared a similar topographic arrangement of neuronal density in the ganglion cell layer. This suggests that the retinal topography did not accompany changes in the foraging ecology throughout evolutionary history for these species of tyrant flycatchers.

A first evaluation on the use of Ardea albus feathers as bioindicators of mercury burden in Amazonian ecosystems

O objetivo deste estudo foi avaliar as concentracoes de mercurio total em penas de Ardea albus coletadas em uma assembleia de aves localizada nas imediacoes da cidade de Belem, Para, com vistas a investigar a possibilidade do uso desta especie nos estudos de biomonitoramento deste metal. Para determinacao de mercurio total foi utilizada a espectrofotometria de absorcao atomica com amalgamacao. A concentracao media de mercurio total nas penas do corpo foi 2,2 ± 1,5 µg.g-1 e nas penas das asas foi 1.3 ± 0.9 µg/g-1. Nao foi observada correlacao entre a concentracao de mercurio total e o comprimento das penas do corpo e da asa. Foi observado teor de mercurio total superior a 5 µg.g-1 em apenas uma amostra de pena do corpo.

Science at the amazonian coast: Scientific production and training of human resources from the Coastal Studies Program – Museu Paraense Emílio Goeldi

The scientific production and the training of human resources in Brazil have been investigated in many knowledge areas to subsidize their scientific, educational and technological development. To disseminate the intellectual and training of human resources contribution of the Coastal Studies Program (PEC/MPEG) at the coastal Amazon, in its timeline (1997 to 2016), it was compiled data of Curriculum Lattes of the PEC researcher and of data banks of institutional Programs of training from the Museu Paraense Emilio Goeldi (MPEG) agreed or not with others teaching and research institutions from Belem do Para that, were typed and analyzed in the EXCELL 10.0 software. The production of 434 published articles (230 in the Biological, Health and Agricultural Sciences Area, 98 in Earth Sciences and Engineering and 76 in Human and Social Sciences) and of 427 training of human resources (128 in the Biological, Health and Agricultural Sciences Area, 128 in Earth Sciences and Engineering and 100 in Human and Social Sciences) mapping quantitatively the intellectual and training of human resources production in a multidisciplinary character, exposing the contribution of the program in its timeline, as also points out gaps and advances that can subsidize the academic and social demands fulfilling its mission.