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Allometric relationship between number of neurons and brain size in a cichlid fish (Oreochromis oossambicus)
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Abstract(s)
Em peixes, crescer em diferentes densidades, aquando do desenvolvimento do indivíduo
originam diferenças no comprimento standard do mesmo. Com o intuito de estudar a relação
alométrica entre o número de neurónios e o tamanho do cérebro, foi realizado um estudo
utilizando o Fraccionador Isotrópico na Tilápia de moçambique (O. mossambicus). De modo a
criar diferenças significativas no tamanho standard, vários indivíduos foram colocados a crescer
em quatro densidades diferentes (15, 30, 60 e 120). Foram analisados dois pontos de
desenvolvimento, sendo estes os cinco meses e os doze meses com 10 indivíduos para cada
densidade. Desta forma, observamos que o aumento do comprimento standard leva a um
aumento do tamanho do cérebro e por consequente a um aumento das macro-áreas a ele
associadas (tronco cerebral, cerebelo, diencéfalo, teto ótico e telencéfalo). Foi ainda observado
que a quantidade das células neuronais e não-neuronais tendem a aumentar proporcionalmente
ao aumento do tamanho do cérebro. Por último foi observado que existe uma diferença no
tamanho do núcleo das células neuronais em comparação com as células não neuronais. Desta
forma, os resultados obtidos apontam para uma relação alométrica entre o número de neurónios,
o tamanho dos núcleos das células e o tamanho do cérebro.
In fish, growing at different densities during the development of the individual leads to differences in their standard length. To study the allometric relationship between neuron number and brain size, the Isotropic Fractionator technique was performed in the Mozambique tilapia (O. mossambicus). To create significant differences in standard length, several individuals were put to grow at four different densities (15, 30, 60 and 120), and they were analyzed at two different development points, five months, and twelve months, with ten individuals per density. It was observed an association between standard length, brain size and the respective macro-areas (brainstem, cerebellum, diencephalon, optic tectum and telencephalon). We also found that the number of neuronal and non-neuronal cells tends to increase as brain size increases. Finally, we show that there is a difference in the nucleus size of neuronal cells compared to non-neuronal cells. Thus, the results obtained indicate that there is evidence of an allometric relationship between the number of neurons and brain size.
In fish, growing at different densities during the development of the individual leads to differences in their standard length. To study the allometric relationship between neuron number and brain size, the Isotropic Fractionator technique was performed in the Mozambique tilapia (O. mossambicus). To create significant differences in standard length, several individuals were put to grow at four different densities (15, 30, 60 and 120), and they were analyzed at two different development points, five months, and twelve months, with ten individuals per density. It was observed an association between standard length, brain size and the respective macro-areas (brainstem, cerebellum, diencephalon, optic tectum and telencephalon). We also found that the number of neuronal and non-neuronal cells tends to increase as brain size increases. Finally, we show that there is a difference in the nucleus size of neuronal cells compared to non-neuronal cells. Thus, the results obtained indicate that there is evidence of an allometric relationship between the number of neurons and brain size.
Description
Dissertação de Mestrado apresentada no
ISPA – Instituto Universitário para obtenção de grau
de Mestre na especialidade de Neurociências
Cognitivas e Comportamentais
Keywords
Fraccionador isotrópico Relação alométrica Tamanho do cérebro Neurónios Densidade neuronal Tilápia de Moçambique Isotropic fractionator Allometric relationship Brain size Neurons Neuronal density Mozambique tilapia