RESUMO
The oxidation of the free nucleoside 2'-deoxyguanosine (dGuo) by singlet molecular oxygen ((1)O2) has been studied over the three last decades due to the major role of DNA oxidation products in process such as ageing, mutation and carcinogenesis. In the present work we investigated the dGuo oxidation by (1)O2 in the presence of the important low molecular antioxidant, glutathione, in its reduced (GSH) and oxidized (GSSG) forms. There were applied different conditions of concentration, pH, time of incubation, and the use of a [(18)O]-labeled thermolabile endoperoxide naphthalene derivative as a source of [(18)O]-labeled (1)O2. Data was obtained through high performance liquid chromatography (HPLC) and HPLC coupled to micrOTOF Q-II analysis of the main oxidation products: the diastereomers of spiroiminodihydantoin-2'-deoxyribonucleosides (dSp) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo). An intriguing result was that 8-oxodGuo levels increased by 100 fold when dGuo was oxidized by (1)O2 in the presence of GSH and by 2 fold in the presence of GSSG, while dSp levels dropped to zero for both conditions. All data from dGuo, 8-oxodGuo and dSp quantification together with the analysis of residual GSH/GSSG content in each sample strongly suggest that glutathione modifies the mechanism of dGuo oxidation by (1)O2 by disfavoring the pathway of dSp formation.
Assuntos
Desoxiguanosina/metabolismo , Glutationa/metabolismo , Oxigênio Singlete/metabolismo , 8-Hidroxi-2'-Desoxiguanosina , Desoxiguanosina/análogos & derivados , Desoxiguanosina/química , Glutationa/química , Dissulfeto de Glutationa/química , Dissulfeto de Glutationa/metabolismo , Guanosina/análogos & derivados , Guanosina/química , Guanosina/metabolismo , Técnicas In Vitro , Modelos Químicos , Oxirredução , Oxigênio Singlete/química , Compostos de Espiro/química , Compostos de Espiro/metabolismoRESUMO
Substrate type determines nesting success and fitness in turtles and is a critical consideration for nesting area protection and restoration. Here, we evaluated the effect of substrate on nest removal by humans in the eastern Brazilian Amazon. We analyzed substrate composition and fate of 216 P. unifilis nests along 88 km of rivers. River segment and substrate type were the most important predictors of nest removal by humans. We found up to 36% lower removal of nests in fine sand and experimental results support the hypothesis that wind more often obscures tracks of nesting females in substrates with more (>66%) fine sand. Our findings are useful for informing the restoration of artificial nesting areas across the Amazon, as nesting area substrates should be selected not only to maintain hatchling sex ratios, but also to minimize nest removal by humans.
Assuntos
Conservação dos Recursos Naturais , Água Doce , Comportamento de Nidação , Areia/química , Animais , Brasil , Feminino , Humanos , Rios , TartarugasRESUMO
The free nucleoside 2'-deoxyguanosine (dGuo) is the most susceptible to oxidation by reactive oxygen species (ROS) compared to the other free nucleosides, and its oxidation product 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) has been used as a biomarker to quantify oxidative stress damage. We investigated different reactions using Fe(2+) or Cu(2+) and H2O2 in order to identify the reaction with the best yield. HPLC coupled with a UV detector and micrOTOF mass spectrometry were used to detect and confirm the identity of 8-oxodGuo. The optimized reaction synthesized 8-oxodGuo with a yield of 72.0%, much higher than that previously described in the literature. Our improved method for 8-oxodGuo synthesis could be extremely useful for assays that require the synthesis of internal standards labeled with stable isotopes.