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Previous issue date: 2017-03-14 / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / The increased use of pesticides has caused the degradation of a variety of ecosystems, especially aquatic environments. Despite specific targets, agrochemicals are able to cause metabolic and functional alterations including in non-target organisms. Amphibians constitute the most globally threatened Class of vertebrates, and the population declines observed around the world are due to a synergy of different factors, including habitat degradation and fragmentation, mostly to agricultural purposes, and the exposure to contaminants derived of these activities, among others. Within this context, Melanophryniscus admirabilis is a micro endemic bufonid toad species, with occurrence registered to only one area in Rio Grande do Sul state (Brazil). This species has a critically endangered (CR) status, at regional, national and global levels. The great danger of extinction is due to several factors, including habitat fragmentation (especially for agricultural purposes) and the decreased habitat quality, mainly because of extensive use of agrochemicals in areas near of the natural habitat of this species. In view of the foregoing, the objective of the present study was to analyze possible alterations in metabolic and oxidative parameters in total homogenate of M. admirabilis tadpoles exposed to two different concentrations of commercial formulation containing Sulfentrazone (Boral? 500 SC) and two concentrations containing Glyphosate (Roundup? Original). The total levels of glycogen, proteins and uric acid were analyzed; as well as the possible occurrence of lipid peroxidation (LPO), expressed by TBARS levels; and the enzymatic activity of Superoxide Dismutase (SOD), Catalase (CAT) and Glutathione S-Transferase (GST). The results showed significant alterations in metabolic and oxidative parameters, in groups exposed to Sulfentrazone and Glyphosate herbicides. Analyzing these results, we hypothesize that the associated mobilization of enzymes and metabolic parameters presumably was capable of counter the oxidative lipid damage in these animals. Despite of that, the observed alterations may affect these animals during its life cycle, especially during and after metamorphic period. The apparent enzymatic inhibition observed in groups exposed to the herbicides, in addition to indicate the great susceptibility of tadpoles to these agents, reflects an impairment of the ability of these animals to cope with adverse and synergistic environmental situations, such as habitat fragmentation, UV radiation and exposure to other pollutants. The absence of mortality suggests resistance of M. admirabilis tadpoles to the tested concentrations of herbicides; nevertheless, the comparison of the antioxidant capacity of this species against taxonomically related species would be relevant. Therefore, the present study has demonstrated that the exposure of M. admirabilis tadpoles to sub lethal concentrations of Sulfentrazone and Glyphosate herbicides has affected the homeostasis, thus affecting the survival, of these animals in later life cycle stages. However, further studies would be necessary, including other concentrations and herbicides, as well as the analysis of further metabolites and components of the antioxidant system of this species. / O incremento no uso de pesticidas vem ocasionando a degrada??o de diferentes ecossistemas, sobretudo aqu?ticos. Apesar de possu?rem aplica??es espec?ficas a determinados organismos, sabe-se que os agrot?xicos s?o capazes de ocasionar altera??es metab?licas e funcionais em diversos organismos n?o alvo. Os anf?bios constituem a Classe de vertebrados mais amea?ada globalmente, sendo que os decl?nios populacionais observados no mundo todo s?o decorrentes da a??o sin?rgica de diversos fatores, incluindo a fragmenta??o e degrada??o de habitat, principalmente para fins agr?colas, a exposi??o a contaminantes derivados destas atividades, dentre outros. Neste contexto, Melanophryniscus admirabilis ? uma esp?cie de sapo bufon?deo micro end?mica, descrita atualmente para apenas uma localidade no estado do Rio Grande do Sul (Brasil), e avaliada como Criticamente em Perigo de extin??o, em n?vel regional, nacional e global. O alto grau de amea?a desta esp?cie deve-se a um conjunto de fatores, como a fragmenta??o e perda de qualidade do habitat, principalmente devido ? convers?o de ?reas para agricultura e ? larga utiliza??o de agrot?xicos no entorno da ?rea de ocorr?ncia da esp?cie. Com isso, o objetivo do presente estudo foi analisar poss?veis altera??es em par?metros metab?licos e do balan?o oxidativo em homogeneizado total de girinos de M. admirabilis expostos a duas concentra??es de formula??o comercial contendo Sulfentrazone (Boral? 500 SC) e outras duas contendo Glifosato (Roundup? Original). Foram analisados os n?veis totais de glicog?nio, prote?nas e ?cido ?rico; a poss?vel ocorr?ncia de lipoperoxida??o (LPO) atrav?s dos n?veis de TBARS; e o n?vel de atividade das enzimas Super?xido Dismutase (SOD), Catalase (CAT) e Glutationa S-Transferase (GST). Os resultados obtidos evidenciaram altera??es significativas nos par?metros mensurados, nos grupos expostos ?s diferentes concentra??es dos herbicidas Sulfentrazone e Glifosato. A partir disto, sugere-se que a mobiliza??o conjunta das enzimas e metab?litos analisados possivelmente foi capaz de conter o dano oxidativo nestes animais. Entretanto, cabe ressaltar que as altera??es observadas podem vir a afetar estes animais ao longo do ciclo de vida, especialmente durante e ap?s o per?odo metam?rfico. A aparente inibi??o enzim?tica observada nos grupos expostos aos herbicidas, al?m de indicar grande suscetibilidade dos girinos frente ? exposi??o a estes agentes, pode refletir um preju?zo da capacidade destes animais em lidar com situa??es ambientais adversas e sin?rgicas, como a fragmenta??o de habitat, radia??o UV e exposi??o a outros poluentes. A aus?ncia de mortalidade nos girinos de M. admirabilis sugere resist?ncia ?s concentra??es dos herbicidas testados; contudo, caberia a compara??o da capacidade antioxidante desta esp?cie com outras esp?cies taxonomicamente pr?ximas. Assim, este estudo demonstrou que a exposi??o de girinos de M. admirabilis a concentra??es subletais dos herbicidas Sulfentrazone e Glifosato conduziu a uma ruptura da homeostase que pode afetar a sobreviv?ncia da esp?cie em etapas futuras de seu ciclo de vida. Seriam relevantes estudos futuros visando ? compreens?o dos efeitos de outras concentra??es e herbicidas, bem como a an?lise de outros metab?litos e componentes do sistema antioxidante desta esp?cie.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/7666 |
| Date | 14 March 2017 |
| Creators | Silva, Patr?cia Rodrigues da |
| Contributors | Oliveira, Guendalina Turcato, Martins, M?rcio Borges |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Zoologia, PUCRS, Brasil, Faculdade de Bioci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | Unknown |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 2008925231902741151, 600, 600, 600, 600, 36528317262667714, -6482652380601267558, -2555911436985713659 |
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