Navegando por Assunto "Aves migratórias"

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Acesso aberto (Open Access)
Alterações da formação hipocampal do Calidris pusilla associadas à migração outonal de longa distância
(Universidade Federal do Pará, 2017-08-31) MAGALHÃES, Nara Gyzely de Morais; DINIZ, Cristovam Guerreiro; http://lattes.cnpq.br/1025250990755299; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
After breeding in the upper Arctic tundra, shorebirds affected by migratory restlessness trace an inherited preliminary route and use compasses, maps and visual landmarks, until they reach, in the northern hemisphere, stopover sites that have the necessary nutritional resources for fast and high gain of energy reserves for migratory journey, as in the Bay of Fundy-Canada. Following this stopover site that is used by 75% of the population of Calidris pusilla, the long-distance autumn migratory experience continues with uninterrupted 6-day non-stop flights over the Atlantic until these birds reach South America and then the island of Canela-Brazil. To test the hypothesis that the long-distance migratory process would influence neurogenesis, astrogenesis and activation of earlier-expression genes, we captured 12 individuals in full migratory activity in the Bay of Fundy and 9 individuals in the Island of Canela in Brazil. After selective immunostaining for mature neurons (NeuN), immature neurons (Dcx), astrocytes (GFAP), and neuronal activation by early genes (c-Fos), we quantified these markers in the hippocampal formation and compared the results of this quantification of the individuals in migration (Bay of Fundy) with those of wintering birds (Canela Island). We used quantitative stereological analyzes to estimate the total number of cells of hippocampal formation, number of active cells, total number of astrocytes and young and mature neurons. To verify if the differences found were statistically significant, we used the Student t test. Our results confirmed that autumnal migration alone, caused hippocampal changes in Calidris pusilla. After migration, we detected that the hippocampal formation has fewer activated cells and fewer astrocytes, more new neurons and greater relative volume in the quantified hemisphere (left hemisphere). However, this process did not influence the number of total cells and mature neurons. We suggest that the difference found between the volume and number of new neurons, of the full migration and wintering individuals, possibly occurred due to the migratory process in combination with local conditions found during the beginning of the wintering period. Taken together our findings demonstrate long-distance migratory shorebirds offer a unique opportunity to investigate many issues related to the cellular neurobiology of migration in general, and, on the neural plasticity associated with hippocampal neuronal and neurogenesis in adult birds.
Acesso aberto (Open Access)
Ensaios estereológicos e morfologia tridimensional na formação hipocampal de aves migratórias marinhas: análise quantitativa da imunomarcação seletiva de neurônios e micróglia em Calidris pusilla e Actitis macularia
(Universidade Federal do Pará, 2013-08-14) DINIZ, Cristovam Guerreiro; SHERRY, David Francis; DINIZ, Cristovam Wanderley Picanço; http://lattes.cnpq.br/2014918752636286
The aim of this report is to describe the hippocampal formation of two migratory birds, Calidris pusilla and Actitis macularia, that leave the cold regions of the Canadian Tundra, escaping the winter, towards the coast of South America and the Caribbean Islands where they remain until winter ends returning to the Northern hemisphere. We intend to describe the qualitative and quantitative morphological organization of the hippocampal formation, using cytoarchitetonics with cresyl violet and immunostaining for neurons and microglia, followed by stereological estimates of the total number of cells identified with selective markers. We intend as well to compare the three-dimensional morphology of hippocampal microglia of these species with those of the dentate gyrus of Wistar rats and Capuchin monkey. The shorebirds used in the characterization were captured in Canela Island, Bragança City, State of Pará, Brazil (0°47'21.95"S and 46°43'7.34"W), as well as in Canada, in the Bay of Fundy, near Johnson's Mills, New Brunswick (45° 50' 19.3" N 64° 31' 5.39" W). The hippocampal formation limits definition was performed employing Nissl staining and immunostaining for NeuN. For the objects of interest definition of stereological estimates and three-dimensional reconstructions we used immunostaining with anti NeuN for neurons and anti-IBA-1 for microglia respectively. The stereological results revealed similar number of neurons in both species whereas the number of microglia in Actitis macularia was 37% higher than in Calidris pusilla. Furthermore, it was found that the hipocampal formation average volume in Actitis macularia was 38% higher than that found in Calidris pusilla. Comparative studies of the microglial morphology with mammals (Rattus novergicus and Cebus apella) revealed significant morphological differences that indicate microglia in birds shows on average lower complexity (smaller fractal dimension), smaller tree volumes and areas and thinner branches than rat and monkey microglia.
Acesso aberto (Open Access)
Microglia and neurons in the hippocampus of migratory sandpipers
(Universidade Federal do Pará, 2015-11) DINIZ, Cristovam Guerreiro; MAGALHÃES, Nara Gyzely de Morais; SOUSA, Aline Andrade de; SANTOS FILHO, Carlos; DINIZ, Daniel Guerreiro; LIMA, Camila Mendes de; OLIVEIRA, Marcus Augusto de; PAULO, Dario Carvalho; PEREIRA, Patrick Douglas Corrêa; SHERRY, David Francis
The semipalmated sandpiper Calidris pusilla and the spotted sandpiper Actitis macularia are long- and short-distance migrants, respectively. C. pusilla breeds in the sub-arctic and mid-arctic tundra of Canada and Alaska and winters on the north and east coasts of South America. A. macularia breeds in a broad distribution across most of North America from the treeline to the southern United States. It winters in the southern United States, and Central and South America. The autumn migration route of C. pusilla includes a non-stop flight over the Atlantic Ocean, whereas autumn route of A. macularia is largely over land. Because of this difference in their migratory paths and the visuo-spatial recognition tasks involved, we hypothesized that hippocampal volume and neuronal and glial numbers would differ between these two species. A. macularia did not differ from C. pusilla in the total number of hippocampal neurons, but the species had a larger hippocampal formation and more hippocampal microglia. It remains to be investigated whether these differences indicate interspecies differences or neural specializations associated with different strategies of orientation and navigation.