Browsing by Subject "bisphenol A"

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  • Le, Thanh Ngoc Uyen (Helsingin yliopisto, 2017)
    The aims of this study were to use the heterologously expressed laccase in Pichia pastoris as oxidative biocatalysts for the degradation of BPA and to find out natural mediators that could assist this laccase to degrade BPA efficiently and environmental friendly. In addition, removal of the estrogenic activity of BPA by the white rot fungus Physisporinus rivulosus cultures and the role of its laccase 2 in the BPA disapperance was also focused. Firstly, the removal of BPA’s estrogenic activity by the white rot fungus Physisporinus rivulosus was confirmed in cultures both with and without the fungal mycelium. Next, the recombinant laccase 2 (rLac2) played a role in the BPA disapperance. At the similar laccase activity level, removal of BPA’s estrogenic activity was done more efficiently in the fungal cultures than in the cell-free enzymatic treatments. Metabolites present in the fungal cultures could possibly act as natural mediators that enhance the removal of BPA. In addition, combination of nine laccases present in the fungal cultures could possibibly enhance the degradation of BPA. Finally, none of the ten mediatiors used was found to act as an efficient rLac2 enhancer in degrading BPA. Degradation of BPA was followed using a bioreporter system. The yeast Saccharomyces cerevisiae has been genetically modified in order to express the estrogen receptor alpha and produce a bioluminescent signal upon contact with estrogenic substances such as BPA. This bioreporter system has been further developed to specifically detect the estrogenic activity of bisphenol A and to be used in a high-throughput manner.
  • Mörtengren, Ariel (Helsingfors universitet, 2016)
    The field of stem cell research is hotter than ever, because still today, the goal for easily achievable stem cells for the use of tissue engineering and stem cell therapies, is yet to be achieved. Also, human stem cell based test systems are potential replacements of present animal test models. The ongoing obesity epidemic creates pressure for scientists to resolve the causes behind it. One way of approaching the problem, is the study of adipogenesis with the use of a in-vitro cell model. This have already been done for a while, with rodent based cell models, but the present study took the human obesity research a bit closer to its subject by using humane adipose tissue derived mesenchymal stem cells (hASC). Also, the adipogenic induction is executed with a human adipose tissue extract (ATE). Epidemiologically, the rise in obesity rates correlates at some level, with the occurrence of known endocrine disrupting chemicals in our environment. These include e.g. some pesticides and plasticizers, such as tributyltin (TBT), bis(2-ethylhexyl)phthalate (DEHP) and bisphenol A (BPA). In the present study, the effects of a variety of concentrations, ranging from 50nM to 100µM of BPA, on ATE induced adipogenesis of hASCs, was studied. The accumulation of triglycerides - a key parameter for adipogenesis - is evaluated with the use of oil-red-o (ORO) staining and photometric measurements. A set of tests was executed to find out if BPA possesses adipogenic, synergistic or antiadipogenic properties in this particular test system. No significant antiadipogenic, nor synergistic effects were seen. Some antiadipogenic effects were seen throughout the study, but without any dose-dependence. This study also showed need for further development of the test. ORO staining needs to be further standardized to increase accuracy, different batches of ATE may cause variation in the results. All and all the test system is relatively easily modified and when fully functional, it is a great tool for screening for substances affecting our adipose tissue, and also for enhancing our knowledge on human adipogenesis in whole.
  • Nair, Vidhya A.; Valo, Satu; Peltomäki, Päivi; Bajbouj, Khuloud; Abdel-Rahman, Wael M. (2020)
    There is an ample epidemiological evidence to support the role of environmental contaminants such as bisphenol A (BPA) in breast cancer development but the molecular mechanisms of their action are still not fully understood. Therefore, we sought to analyze the effects of three common contaminants (BPA; 4-tert-octylphenol, OP; hexabromocyclododecane, HBCD) on mammary epithelial cell (HME1) and MCF7 breast cancer cell line. We also supplied some data on methoxychlor, MXC; 4-nonylphenol, NP; and 2-amino-1-methyl-6-phenylimidazo [4-b] pyridine, PhIP. We focused on testing the prolonged (two months) exposure to low nano-molar concentrations (0.0015-0.0048 nM) presumed to be oncogenic and found that they induced DNA damage (evidenced by upregulation of pH2A.X, pCHK1, pCHK2, p-P53) and disrupted the cell cycle. Some agents induced epigenetic (methylation) changes of tumor suppressor genes TIMP3, CHFR, ESR1, IGSF4, CDH13, and GSTP1. Obviously, the accumulation of these molecular alterations is an essential base for cancer development. Consistent with this, we observed that these agents increased cellular invasiveness through collagen. Cellular abilities to form colonies in soft agar were increased for MCF7. Toxic agents induced phosphorylation of protein kinase such as EGFR, CREB, STAT6, c-Jun, STAT3, HSP6, HSP27, AMPK alpha 1, FAK, p53, GSK-3 alpha/beta, and P70S6 in HME1. Most of these proteins are involved in potential oncogenic pathways. Overall, these data clarify the molecular alterations that can be induced by some common environmental contaminants in mammary epithelial cells which could be a foundation to understand environmental carcinogenesis.
  • Pflugmacher, Stephan; Sulek, Amalia; Mader, Hannah; Heo, Jeongin; Noh, Ji Hyeon; Penttinen, Olli-Pekka; Kim, Youngjun; Kim, Sanghun; Esterhuizen, Maranda (2020)
    With the increase in environmental monitoring and assessing, we are gaining insight into the extent of microplastic pollution in our environment. The threat posed by microplastics to biota could come, e.g., from leached substances. As some plastic materials have been decaying in nature for extended periods already, the toxic effects of leaching compounds need to be investigated. It is furthermore essential to understand the adverse effects of new plastic and how these effects differ from the effects elicited by old plastic material. Therefore, in the present study, the effects of exposure to leachates from new and artificial aged polycarbonate as well as new and aged polycarbonate granules on various germination parameters of Lepidium sativum were studied. Germination, root, and shoot length, as well as the calculated germination rate index as a measure for germination speed, was negatively influenced in substrate-free and substrate containing exposures. From an ecological and agricultural point of view, this implies possible yield losses with less germinating seeds, slower plant germination speed, and smaller seedlings in general.