Estudo da potencial relação da aneuploidia com a condição fisiológica e o crescimento na amêijoa-boa ruditapes decussatus
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Data
2010
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Tendo em conta o elevado interesse da amêijoa–boa, Ruditapes decussatus em termos económicos, em Portugal, este trabalho foi importante para a compreensão de um dos principais problemas no cultivo desta espécie, o crescimento. Nos últimos anos, para além de se observar uma grande variabilidade na taxa de crescimento, o tamanho dos indivíduos capturados tem vindo a sofrer, uma acentuada diminuição. Frequentemente, numa mesma ‘cohort’, esta espécie apresenta dois tipos de indivíduos, os que crescem mais rapidamente, os chamados ‘Fast-Growers’ e os que crescem mais lentamente, os ‘Slow-Growers’. Este fenómeno ocorre, apesar dos indivíduos estarem sujeitos às mesmas condições de cultivo.
O principal objectivo deste trabalho foi estudar as possíveis diferenças entre ‘Fast-Growers’ e ‘Slow-Growers’ de uma mesma ‘cohort’ de R. decussatus a nível das possíveis alterações cromossómicas numéricas existentes, aneuploidia, e a nível da fisiologia, nomeadamente na avaliação do índice de condição e na análise da composição bioquímica. Foi igualmente realizado um estudo com o objectivo de identificar os cromossomas ausentes nos casos de aneuploidia.
Os resultados obtidos sugerem pela primeira vez a existência de uma correlação negativa entre a aneuploidia e o crescimento nesta espécie. Verificou-se igualmente uma perda cromossómica preferencial nos pares 1, 6, 12 e 19.
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Given the commercial importance of the carpet shell, Ruditapes decussatus in Portugal, this work contributed to understand one of the main problems in the production of this species, the growth rate. In addition to an observed high growth rate variability, a decrease in the maximum size reached by the individuals of this species has been noticed in the last years. Usually, in the same cohort, this species presents two groups of individuals, the Fast-Growers and the Slow-Growers according to their shell length. This variability occurs, although individuals are reared under common conditions. The main objective of this work was to study the possible differences between ‘Fast-Growers’ and ‘Slow-Growers’ of the same cohort of R. decussatus in terms of eventual numerical chromosomal changes, aneuploidy, and the level of physiological capacity, by assessing the condition index and the biochemical composition. The identification of the missing chromosomes in aneuploid situations was also performed. The results of this study showed for the first time the existence of a negative correlation between aneuploidy and growth rate in this species. A preferential chromosomal loss was observed in pairs 1, 6, 12 and 19.
Given the commercial importance of the carpet shell, Ruditapes decussatus in Portugal, this work contributed to understand one of the main problems in the production of this species, the growth rate. In addition to an observed high growth rate variability, a decrease in the maximum size reached by the individuals of this species has been noticed in the last years. Usually, in the same cohort, this species presents two groups of individuals, the Fast-Growers and the Slow-Growers according to their shell length. This variability occurs, although individuals are reared under common conditions. The main objective of this work was to study the possible differences between ‘Fast-Growers’ and ‘Slow-Growers’ of the same cohort of R. decussatus in terms of eventual numerical chromosomal changes, aneuploidy, and the level of physiological capacity, by assessing the condition index and the biochemical composition. The identification of the missing chromosomes in aneuploid situations was also performed. The results of this study showed for the first time the existence of a negative correlation between aneuploidy and growth rate in this species. A preferential chromosomal loss was observed in pairs 1, 6, 12 and 19.
Descrição
Orientação : Gonçalo Calado ; co-orientação: Alexandra Leitão ; Domitília Matias
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MESTRADO EM BIOLOGIA DO DESENVOLVIMENTO, BIOLOGIA, BIOLOGY, CROMOSSOMAS, CHROMOSOMES, CRESCIMENTO, GROWTH, MOLUSCOS BIVALVES, BIVALVE, FISIOLOGIA ANIMAL, ANIMAL PHYSIOLOGY