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Buenos Aires, Argentina

Sztrum A.A.,Institute Ciencias Ambientales y Salud | Sztrum A.A.,CONICET | Sabatini S.E.,CONICET | Sabatini S.E.,University of Buenos Aires | Rodriguez M.C.,University of Buenos Aires

The effect of copper-imposed oxidative stress on isocitrate lyase (ICL) activity was studied in a Chlamydomonas reinhardtii wild type and a copper-tolerant pleiotropic mutant strain. Suspension batch bioassays were performed adding copper chloride under moderate irradiation. Two harvest points were selected to represent the acute and restoration phases and oxidative stress indicators were measured: antioxidative metabolites, phenolic compounds, ascorbic acid, abundance of thiobarbituric reactive substances, and activities of detoxifying enzymes such as catalase and ascorbate peroxidase. Copper stress under moderate irradiance favours acetate assimilation through enhanced ICL activity, especially in the acute phase. Though the mutant strain exhibited at least twofold ICL activity in the acute phase compared to the wild type, there was no significant difference in copper tolerance between strains. The higher ICL activity under copper stress may be an adaptation to promote mixotrophic organic carbon assimilation when photosynthetic carbon dioxide fixation is impaired. Thus, the higher ICL activity has the potential to be a useful indicator in acetate-flagellate bioassays. Source

Fonovich T.M.,National University of San Martin of Argentina | Perez-Coll C.S.,National University of San Martin of Argentina | Perez-Coll C.S.,Institute Investigacion e Ingenieria Ambiental | Fridman O.,Interamerican Open University | And 2 more authors.
Comparative Biochemistry and Physiology Part - C: Toxicology and Pharmacology

We report phospholipid changes in Rhinella arenarum embryos after applying three acclimation protocols to copper between 40 and 420 ng L− 1. The lower and higher acclimation treatments resulted in embryos' enhanced resistance to this metal. Phospholipid remodeling activity, evident through arachidonic acid radioactivity incorporation increase in phosphatidylcholine (PC) and sphingomyelin (SPH) fractions, was registered in embryos acclimated to the intermediate exposure condition. Concomitantly, a decrease in phosphatidic acid fraction (PA) was registered in the higher acclimation condition. PC/PE radioactivity ratio increased both for medium and high acclimation conditions from 0.493 in control embryos to 1.378 and 1.032 respectively. Phospholipid changes could be relevant for changes in membrane features associated with low level exposures to copper, preparing the embryo for a higher resistance to this metal. The increased resistance to copper could also be associated with both an increase in metallothioneins concentration, as registered with HPLC in all the acclimation conditions, and an increase in the copper bound to the third fraction of metallothioneins separated by this method. Our results point out that even very low level exposure to copper results in phospholipid metabolism changes that could be relevant for the acclimation phenomena. © 2016 Elsevier Inc. Source

Svartz G.V.,Institute Ciencias Ambientales y Salud | Herkovits J.,Institute Ciencias Ambientales y Salud | Perez-Coll C.S.,Institute Investigacion e Ingenieria Ambiental 3iA UNSAM

Atrazine (ATR), one of the most widely used herbicides in the world, affects not only target organisms but also the biota in general. Here, the teratogenic and neurotoxic effects of ATR on Rhinella arenarum (South American toad) embryos, and larvae were evaluated by means of standardized bioassays during acute and chronic exposures. The herbicide had a significant incidence of malformations, with a Teratogenic Index (TI) of 3.28. The main effects were delayed development, reduced body size, microcephaly, axial flexures, wavy tail and edema. In addition, delayed development, reduced development of forelimbs, and edema were recorded at metamorphosis stages. Scanning electron microscopy allowed observing different degrees of cellular dissociation and persistent cilliar cells in specific regions like the adhesive structure and tail fin. Results obtained by ATR 24 h pulse exposures at six developmental stages pointed out blastula as the most susceptible developmental stage both for immediate and delayed adverse effects. A noteworthy recovery capacity from acute toxic effects was recorded from the neural plate stage onwards. Regarding neurotoxic effects, abnormal, and erratic swimming and spasmodic contractions were recorded. Both the teratogenic and neurotoxic effects reported in this study demonstrate the importance of evaluating sublethal effects in non-target organisms as they could imply reduced fitness of individuals and eventually a population decline. The Hazard Quotients (HQ) for ATR ranged from 0.14 to 10.80, and the fact that some of these values are above USEPA's level of concern indicate that ATR is likely a risk to R. arenarum. © Springer Science+Business Media, LLC 2012. Source

Sztrum A.A.,Institute Ciencias Ambientales y Salud | D'Eramo J.L.,Institute Ciencias Ambientales y Salud | Herkovits J.,Institute Ciencias Ambientales y Salud
Environmental Toxicology and Chemistry

Nickel, a widely distributed heavy metal in the biosphere, produces systemic, carcinogenic, and teratogenic effects. The objectives of the present study are to report the acute, short-term chronic, and chronic toxicity of Ni in Rhinella arenarum embryos as well as the stage-dependent susceptibility to this heavy metal, including oxygen consumption, teratogenesis, and adverse effects on cell differentiation processes. The stages evaluated were blastula (S.7), gastrula (S.11), tail bud (S.17), fin circulation (S.22), and complete operculum (S.25), in this last case by means of toxicity profile curves. Nickel increases its adverse effects gradually, with a maximum value after 96h. The 50% lethal concentrations (LC50s) for 96, 168, and 240h at S.25 were 1.14, 0.60, and 0.48mg Ni2+/L, respectively; S.11 and S.22 were the least and most susceptible to Ni with, LC50s 96h of 6.12 and 0.19mg Ni2+/L, respectively. A reduction of approximately 25% in oxygen consumption anticipates lethal effects from S.17 onward. The main teratogenic effects were retarded growth and development, extremely severe axis incurvations, persistent yolk plug, asymmetry, microcephaly and mouth and gill agenesia, and limited neuromuscular activity. Ciliated cells were not functional. The possibility of associating the remarkable stage-dependent susceptibility to Ni with environmental changes during the evolutionary process is also considered. © 2011 SETAC. Source

Herkovits J.,Institute Ciencias Ambientales y Salud | Castanaga L.A.,Institute Ciencias Ambientales y Salud | D'Eramo J.L.,Institute Ciencias Ambientales y Salud | Jourani V.P.,Institute Ciencias Ambientales y Salud

The LC10, 50 and 90/24h of aluminum for Rhinella arenarum embryos at complete operculum stage were 0.55, 0.75 and 1mgAl3+/L respectively. Those values did not change significantly by expanding the exposure period till 168h. The aluminum toxicity was evaluated in different pH conditions by means of a citrate buffer resulting for instance, 1mgAl3+/L at pH 4, 4.1, 5 and 6 in 100%, 70%, 35% and 0% of lethality respectively. As an outstanding feature, the embryos changed the pH of the maintaining media both in the case of Al3+ or citrate buffer treatments toward neutral. 10 embryos in 40mL of AMPHITOX solution were able to increase the pH from 4.2 to 7.05, a fact related with a metabolic shift resulting in an increase in nitrogen loss as ammonia. Our study point out the natural selection of the most resistant amphibian embryos both for pH or aluminum as well as the capacity of living organisms (as a population) to alter their chemical environment toward optimal conditions for their survival. As these facts occur at early life stages, it expand the concept that living organisms at ontogenic stages are biomarker of environmental signatures of the evolutionary process (Herkovits, 2006) to a global Onto-Evo concept which imply also the feedback mechanisms from living organisms to shape environmental conditions in a way that benefits them. © 2015 Elsevier Ltd. Source

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