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Besaury, L., Ouddane, B., Pavissich, J. P., Dubrulle-Brunaud, C., Gonzalez, B., & Quillet, L. (2012). Impact of copper on the abundance and diversity of sulfate-reducing prokaryotes in two chilean marine sediments. Mar. Pollut. Bull., 64(10), 2135–2145.
Abstract: We studied the abundance and diversity of the sulfate-reducing prokaryotes (SRPs) in two 30-cm marine chilean sediment cores, one with a long-term exposure to copper-mining residues, the other being a non-exposed reference sediment. The abundance of SRPs was quantified by qPCR of the dissimilatory sulfite reductase gene beta-subunit (dsrB) and showed that SRPs are sensitive to high copper concentrations, as the mean number of SRPs all along the contaminated sediment was two orders of magnitude lower than in the reference sediment. SRP diversity was analyzed by using the dsrB-sequences-based PCR-DGGE method and constructing gene libraries for dsrB-sequences. Surprisingly, the diversity was comparable in both sediments, with dsrB sequences belonging to Desulfobacteraceae, Syntrophobacteraceae, and Desulfobulbaceae, SRP families previously described in marine sediments, and to a deep branching dsrAB lineage. The hypothesis of the presence of horizontal transfer of copper resistance genes in the microbial population of the polluted sediment is discussed. (C) 2012 Elsevier Ltd. All rights reserved.
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Garcia-Huidobro, M. R., Poupin, M. J., Urrutia, C., Rodriguez-Navarro, A. B., Grenier, C., Vivanco, J. F., et al. (2021). An intrapopulational study of organic compounds and biomechanical properties of the shell of the Antarctic bivalve Laternula elliptica (P. P. King, 1832) at King George Island. Polar Biol., 44, 1343–1352.
Abstract: Laternula elliptica is a key bivalve species and widely distributed around the Antarctic continent. This bivalve has been the study subject in several studies centered on ecological, physiological, biochemical, and behavioral patterns. However, little is known about the chemistry and the biomechanical properties of the shells of this mollusk. Here, we present the first report of the intra-population variability in the organic composition and mechanical properties of L. elliptica shells. Further, we analyze different morphological traits and their association with the metabolism of a population of L. elliptica from King George Island, Western Antarctic Peninsula. The summer metabolic rates and the hepatosomatic index values indicate good health conditions of this clam's population. Shell periostracum chemistry is quite similar to bivalves from temperate regions, but the relative amount of protein increased ca. five-fold in shells of L. elliptica. The microhardness is approximately 32% lower than in bivalves from temperate regions. Our characterization of the L. elliptica shells suggests that periostracum chemistry could be specially fitted to avoid shell carbon exposure to dissolution (e.g., in corrosive acidified seawater). In contrast, the reduction in shell hardness may result from prioritizing behavioral (burial) and shell repairing strategies to confront biological (predators) and physical disturbances (e.g., ice scouring). Similar studies in other Antarctic mollusks will help understand the role of shell structure and function in confronting projected climate changes in the Antarctic ocean.
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Govindan, R., Gnanasekaran, C., Govindan, R., Muthuchamy, M., Quero, F., Jothi, A., et al. (2023). Anti-quorum Sensing and Anti-biofilm Effect of Nocardiopsis synnemataformans RMN 4 (MN061002) Compound 2,6-Di-tert-butyl, 1,4-Benzoquinone Against Biofilm-Producing Bacteria. Appl. Biochem. Biotechnol., Early Access.
Abstract: In this study, the anti-biofilm compound of 2,6-Di-tert-butyl, 1,4-benzoquinone was purified from Nocardiopsis synnemataformans (N. synnemataformans) RMN 4 (MN061002). To confirm the compound, various spectroscopy analyses were done including ultraviolet (UV) spectrometer, Fourier transform infrared spectroscopy (FTIR), analytical high-performance liquid chromatography (HPLC), preparative HPLC, gas chromatography-mass spectroscopy (GC-MS), liquid chromatography-mass spectroscopy (LC-MS), and 2D nuclear magnetic resonance (NMR). Furthermore, the purified compound was shown 94% inhibition against biofilm-producing Proteus mirabilis (P. mirabilis) (MN396686) at 70 mu g/mL concentrations. Furthermore, the metabolic activity, exopolysaccharide damage, and hydrophobicity degradation results of identified compound exhibited excellent inhibition at 100 mu g/mL concentration. Furthermore, the confocal laser scanning electron microscope (CLSM) and scanning electron microscope (SEM) results were shown with intracellular damages and architectural changes in bacteria. Consecutively, the in vivo toxicity effect of the compound against Artemia franciscana (A. franciscana) was shown to have a low mortality rate at 100 mu g/mL. Finally, the molecular docking interaction between the quorum sensing (QS) genes and identified compound clearly suggested that the identified compound 2,6-Di-tert-butyl, 1,4-benzoquinone has anti-quorum sensing and anti-biofilm activities against P. mirabilis (MN396686).
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Lardies, M. A., Caballero, P., Duarte, C., & Poupin, M. J. (2021). Geographical Variation in Phenotypic Plasticity of Intertidal Sister Limpet's Species Under Ocean Acidification Scenarios. Front. Mar. Sci., 8, 647087.
Abstract: Ocean Acidification (OA) can have pervasive effects in calcifying marine organisms, and a better understanding of how different populations respond at the physiological and evolutionary level could help to model the impacts of global change in marine ecosystems. Due to its natural geography and oceanographic processes, the Chilean coast provides a natural laboratory where benthic organisms are frequently exposed to diverse projected OA scenarios. The goal of this study was to assess whether a population of mollusks thriving in a more variable environment (Talcaruca) would present higher phenotypic plasticity in physiological and morphological traits in response to different pCO(2) when compared to a population of the same species from a more stable environment (Los Molles). To achieve this, two benthic limpets (Scurria zebrina and Scurria viridula) inhabiting these two contrasting localities were exposed to ocean acidification experimental conditions representing the current pCO(2) in the Chilean coast (500 mu atm) and the levels predicted for the year 2100 in upwelling zones (1500 (mu atm). Our results show that the responses to OA are species-specific, even in this related species. Interestingly, S. viridula showed better performance under OA than S. zebrina (i.e., similar sizes and carbonate content in individuals from both populations; lower effects of acidification on the growth rate combined with a reduction of metabolism at higher pCO2). Remarkably, these characteristics could explain this species' success in overstepping the biogeographical break in the area of Talcaruca, which S. zebrina cannot achieve. Besides, the results show that the habitat factor has a strong influence on some traits. For instance, individuals from Talcaruca presented a higher growth rate plasticity index and lower shell dissolution rates in acidified conditions than those from Los Molles. These results show that limpets from the variable environment tend to display higher plasticity, buffering the physiological effects of OA compared with limpets from the more stable environment. Taken together, these findings highlight the key role of geographic variation in phenotypic plasticity to determine the vulnerability of calcifying organisms to future scenarios of OA.
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Vera, R., Valverde, B., Olave, E., Diaz-Gomez, A., Sanchez-Gonzalez, R., Munoz, L., et al. (2022). Corrosion Behavior of Copper Exposed in Marine Tropical Atmosphere in Rapa Nui (Easter Island) Chile 20 Years after MICAT. Metals, 12(12), 2082.
Abstract: Atmospheric corrosion of copper, exposed on a tropical island in the South-Central Pacific Ocean, was reported and compared with those of a very similar study at the same site conducted 20 years earlier. The new measurements-taken over three years of exposure, from 2010 to 2013-quantified corrosion by mass loss, characterized corrosion products by X-ray diffraction (DRX) and Raman techniques, observed the attack morphology by Scanning Electron Microscope (SEM), and evaluated the patina resistance using electrochemical techniques. The results showed a copper corrosivity category of C4, and the main copper patina compound, cuprite, was porous, nonhomogeneous, and thin. Electrochemical measurements showed cuprite layer growth as a function of the exposure time, and the morphology did not favor corrosion protection. Finally, when comparing the results to those of a study 22 years previous, the copper corrosion rates increased only slightly, even with increased contaminants associated with growing local populations and continuous tourism on the island.
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Vera, R., Valverde, B., Olave, E., Sanchez, R., Diaz-Gomez, A., Munoz, L., et al. (2023). Atmospheric corrosion and impact toughness of steels: Case study in steels with and without galvanizing, exposed for 3 years in Rapa Nui Island. Heliyon, 9(7), e17811.
Abstract: We studied atmospheric corrosion on Rapa Nui Island, using galvanized and non-galvanized SAE 1020 steel samples exposed on racks. We also added Charpy samples of both materials to directly determine the effect of corrosion rate on these materials' impact toughness. The results indicated a correlation between corrosion rate and toughness loss in the studied materials. In the corrosion study, we could also demonstrate the effect from increased insular population growth on con-taminants which aid atmospheric corrosivity. Results showed that atmospheric SO2 has tripled compared with similar corrosion studies done 20 years ago (Mapa Iberoamericano de Corrosi & PRIME;on, MICAT), increasing corrosion rates. Our results show how human factors can influence changes in environmental variables that strengthen corrosion.
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