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Interconnection between PHA and Stress Robustness of Bacteria
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Stanislav Obruca, Petr Sedlacek, Iva Pernicova, Adriana Kovalcik, Ivana Novackova, Eva Slaninova, Ivana Marova
Generally, microorganisms surviving in extreme conditions are called extremophiles. In the literature, the term for ultraviolet radiation-resistant (UVR) microorganisms which are known for the production of various metabolites such as pigments, mycosporine-like amino acids, melanin, pannarin and sphaerophorin, can be found [75,76]. Another group of UVR microorganisms possesses the capability to repair already-changed DNA due to their specific enzymes, e.g. photolyases, which directly break covalent bonding between pyrimidine dimers to form original pyrimidine monomers. This process is known as photoreactivation and it requires light in the near U/blue light (300–500 nm) region as an energy source [72,77]. Another enzymatic DNA repair pathway includes the DNA glycosylase base excision repair (BER) where the glycosyl bond between damaged base and deoxyribose is hydrolyzed. Next, DNA repair mode is based on the repair enzyme called UV-damage endonuclease (UVDE) which can recognize the photoproducts and cut them out immediately. The last of the most frequently used DNA repair pathways which was identified is the nucleotide excision repair (NER) which belongs to the main defensive strategies against UV radiation. This strategy consists of the removal of a damaged oligonucleotide [72,77,78].
DNA damage in mononuclear cells following maximal exercise in sedentary and physically active lean and obese men
Published in European Journal of Sport Science, 2021
Alessandra Peres, Igor M. Da Silva, Maeli Santos, Ângela Beretta, Vanessa Moraes Andrade, Pedro R. T. RomãO, Gilson P. Dorneles
In this study, we incubated PBMC with H2O2 for 4 h. However, H2O2 levels are rapidly metabolized after 20 min and completed decomposed after 2 h of incubation (Jancura, Stanicova, Palmer, & Fabian, 2014). Thus, the lower DNA damage index in PBMC of lean groups and exercised obese individuals may be related to an upregulation of DNA repair enzymes and not necessarily represent a tolerance against oxidative stress exposure. In this sense, future studies should evaluate the role of exercise training status on PBMC DNA damage after oxidative stress challenge for different incubation times (i.e. 5, 20 min, 2, and 4 h). Furthermore, more biochemical assays (i.e. neutral comet assay and 8-oxoguanine DNA glycosylase evaluation, should be conducted to evaluate parameters single-strand break and double-strand breaks and base excision repair.
Chemopreventive effect of troxerutin against hydrogen peroxide-induced oxidative stress in human leukocytes through modulation of glutathione-dependent enzymes
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Bruno Coêlho Cavalcanti, João Batista de Andrade Neto, Antônio Adailson de Sousa Silva, Francisco Stefânio Barreto, José Roberto de Oliveira Ferreira, Hemerson Iury Ferreira Magalhães, Cecília Rocha da Silva, Ícaro Gusmão Pinto Vieira, Nágila Maria Pontes Silva Ricardo, Hélio Vitoriano Nobre Júnior, Manoel Odorico Moraes
Fetal bovine serum (FBS) and Dulbecco’s modified eagle medium (DMEM) were purchased from Cultilab (Campinas, SP, Brazil). RPMI 1640, trypsin-EDTA, glutamine, penicillin, streptomycin, phytohemagglutinin (PHA), low-melting-point agarose, and agarose were purchased from Invitrogen (Carlsbad, CA, USA). Cytochalasin-B, reduced glutathione (GSH), oxidized glutathione (GSSG), 5,5ʹ-dithiobis (2-nitrobenzoic acid) (Ellman’s Reagent, DTNB), dihydronicotinamide adenine dinucleotide phosphate tetrasodium salt (NADPH), methyl methanesulfonate (MMS), and Alamar Blue cell viability reagent were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). 8-oxoguanine DNA glycosylase (hOGG1) was obtained from New England BioLabs (USA). N-(1-naphthyl)-ethylenediamine dihydrochloride was purchased from Merck (USA). Hydrogen peroxide (H2O2) was obtained from Vetec (Brazil). Doxorubicin (Doxolem®) was purchased from Zodiac Produtos Farmacêuticos S/A (Brazil). All other chemicals and reagents used were of analytical grade.
Licochalcone A, a licorice flavonoid: antioxidant, cytotoxic, genotoxic, and chemopreventive potential
Published in Journal of Toxicology and Environmental Health, Part A, 2020
Karoline Soares de Freitas, Iara Silva Squarisi, Nathália Oliveira Acésio, Heloiza Diniz Nicolella, Saulo Duarte Ozelin, Matheus Reis Santos de Melo, Ana Paula Prado Guissone, Gabriela Fernandes, Lívia Mara Silva, Ademar Alves da Silva Filho, Denise Crispim Tavares
The results obtained by the in vitro MN test also showed that LicoA diminished the damage initiated by MMS. This SN2 alkylating agent exhibits high affinity for nitrogen in purines, resulting in N-alkylation. The methylation process mediated by MMS leads to formation of adducts such as N7- and N3-methyladenine, which induce double-strand breaks or inhibit DNA replication. If not repaired, these events are responsible for mutagenic consequences (Kaina 2004; Wyatt and Pittman 2006). DNA damage mediated by these agents is mainly repaired by base excision repair, with the participation of glycosylases. The N7- and N3-methyladenine adducts are repaired by DNA glycosylase (Baute and Depicker 2008; Sedgwick 2004). LicoA exhibited antimutagenic activity against the direct-acting alkylating agent N-methyl-N-nitrosourea as demonstrated by the Ames test (Inami et al. 2017).