Banca de DEFESA: LORAINNY CAROLINA LUCENA DE SOUZA

CYTOTOXIC, GENOTOXIC AND MUTAGENIC EVALUATION OF WATER FROM STREAMWAYS IN THE CITY OF PORTO VELHO – RO IN BIOASSAYS WITH ONION (Allium cepa)

Environmental mutagenicit; Cytogenetics; Water resources; micronucleus test.

The problem of water contamination in water bodies in the city of Porto Velho-RO can lead to damage to the genetic material. This work aims to evaluate the water quality of three streams (UNIR, VIENA and PRUDENTE DE MORAES) in terms of toxicity, cytotoxicity, genotoxicity, in addition to predicting possible mutagenic effects. Six bulbs of Allium cepa were cultivated per stream and two comparison controls (Negative control: distilled water and positive control: 800 mg/l of paracetamol), where the roots after 96 hours of growth were collected, measured, and fixed in Carnoy (3 :1) for 20 hours. After the fixation, washing, hydrolysis and perforation procedure, these slides were stained with 2% Giemsa and the cells analyzed under optical microscopy. For each bulb, the sizes of the three largest roots were measured and 3 slides were produced in which 1000 cells were counted per slide, checking the number of dividing cells, the number of chromosomal aberrations and the amount of micronuclei. With these data, a database was created from which the MI (mitotic index), AC (chromosomal aberrations) and MN (Micronucleus Index) were calculated. Statistical analysis was performed using the Graphpad Prism 8 program, the Kruskal-Wallis test and multiple comparisons using the Dunn's test, where p<0.05. Our results showed that the Igarapé Prudente de Morais during the rainy season showed toxicity (p<0.017), genotoxicity (p<0.0006) and high micronucleus index (p<0.014). Although it was initially classified as a medium-impact stream, the VIENA stream also showed, for the flood period, toxic (p<0.038), genotoxic (p<0.004) and high Micronucleus index (p<0.0029). For the UNIR stream, even though toxic (p>0.05) and cytotoxic (p>0.05) effects have not been proven, it also showed a high rate of chromosomal aberrations (p<0.0175) also for the rainy season. During this period, in the city of Porto Velho, there is a higher probability of contamination of living organisms by water bodies due to flooding. This may be associated with the low level of sanitary conditions in the city of Porto Velho-RO and the carrying of residues and chemical elements, and it is necessary to carry out further investigations in the waters of these streams with other biological assays, a complete physical-chemical analysis, in addition to analysis of trace elements to identify the origin of DNA damage so that we can deepen the knowledge related to damage due to water pollution.