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Master's Dissertation
DOI
10.11606/D.21.2007.tde-05112007-170347
Document
Author
Full name
Keyi Ando Ussami
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Ngan, Phan Van (President)
Gianesella, Sonia Maria Flores
Morales, Maria Aparecida Marin
Title in Portuguese
Ensaio cometa em microalgas marinhas: danos no DNA de Dunaliella tertiolecta Butcher 1959 causados pela exposição à 4-nitroquinolina-N-óxido e ao benzo [a] pireno
Keywords in Portuguese
4- nitroquinolina-N-óxido
benzo[a]pireno
coloração
danos no DNA
ecotoxicologia
ensaio cometa
índice de danos
microalgas
Abstract in Portuguese
Dunaliella tertiolecta, uma alga verde fitoplanctônica de ampla distribuição no ambiente marinho, foi escolhida como organismo teste para estudar a possibilidade de ser utilizada no ensaio cometa, um teste de detecção de danos no DNA em células individualizadas muito utilizado na ecotoxicologia. Essas algas foram facilmente lisadas pela solução de lise alcalina iônica, seus cometas foram corados eficientemente pelo brometo de etídio e pela prata, e a análise por índice de danos apresentou boa correlação com momento de cauda, comprimento de cauda e porcentagem de DNA na cauda. As algas foram expostas a concentrações crescentes de 4-nitroquinolina-N-óxido (4NQO) e benzo[a]pireno (BAP) por 1, 2 e 4 h no escuro. Após somente 1 h de exposição, observou-se um aumento significativo de danos no DNA das algas expostas a 0,25 µM de 4NQO, demonstrando a sensibilidade das mesmas em relação a células de animais. Os dados obtidos da exposição ao BAP não foram consistentes e necessitam de verificação. A metabolização de BAP em compostos tóxicos pelas algas e o efeito das condições de luminosidade antes e durante as exposições são discutidos. Os resultados indicam que D. tertiolecta pode ser utilizada em laboratório para avaliação de genotoxicidade na água através do ensaio cometa.
Title in English
Comet assay in marine microalgae: DNA damage in Dunaliella tertiolecta Butcher 1959 caused by exposure to 4-nitroquinoline-N-oxide and benzo[a]pyrene
Keywords in English
4-nitroquinoline-Noxide
benzo[a]pyrene
comet assay
damage index
DNA damage
ecotoxicology
microalgae
staining
Abstract in English
D. tertiolecta, a phytoplanktonic green algae with ubiquitous distribution in the marine environment, was chosen as a test organism to study the possibility of being used in the comet assay, a frequently used test in ecotoxicology to detect DNA damage in single cells. These algae were easily lised by the alkaline ionic lysis solution, their comets were efficiently stained by ethidium bromide and silver and the damage index was well correlated to tail moment, tail length and percentage of DNA in the tail. The algae were exposed to increasing concentrations of 4-nitroquinoline-N-oxide (4NQO) and benzo[a]pyrene (BAP) for 1, 2 and 4 h in the dark. After 1 h exposure, a significant increase in the DNA damage of algae exposed to 0,25 µM of 4NQO was observed, demonstrating their sensitivity in relation to cells from animals. The data of BAP exposure were not consistent and need further verification. The metabolization of BAP to toxic compounds by algae and the light conditions before and during exposure are discussed. The results indicate that D. tertiolecta can be used in laboratory to evaluate water genotoxicity with comet assay.
 
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KeyiAndoUssami.pdf (1.48 Mbytes)
Publishing Date
2007-11-29
 
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