title: Living organisms influence on environmental conditions: pH modulation by amphibian embryos versus aluminum toxicity.
abstract: The LC10, 50 and 90/24h of aluminum for Rhinella arenarum embryos at complete operculum stage were 0.55, 0.75 and 1mgAl(3+)/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, 1mgAl(3+)/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 Al(3+) 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.
authors.affiliation: Instituto de Ciencias Ambientales y Salud, Fundacion PROSAMA, Paysandú 752, 1405 Buenos Aires, Argentina. Electronic address: herkovit@retina.ar.
authors.forename: Jorge
authors.initials: J
authors.lastname: Herkovits
authors.affiliation: Instituto de Ciencias Ambientales y Salud, Fundacion PROSAMA, Paysandú 752, 1405 Buenos Aires, Argentina.
authors.forename: Luis Alberto
authors.initials: LA
authors.lastname: Castañaga
authors.affiliation: Instituto de Ciencias Ambientales y Salud, Fundacion PROSAMA, Paysandú 752, 1405 Buenos Aires, Argentina.
authors.forename: José Luis
authors.initials: JL
authors.lastname: D'Eramo
authors.affiliation: Instituto de Ciencias Ambientales y Salud, Fundacion PROSAMA, Paysandú 752, 1405 Buenos Aires, Argentina.
authors.forename: Victoria Platonova
authors.initials: VP
authors.lastname: Jourani
mesh_terms: D000535:Aluminum / Q000633:toxicity*; D000818:Animals; D002025:Bufonidae; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D004777:Environment; D006863:Hydrogen-Ion Concentration; D012996:Solutions
chemical_list: D012996:Solutions; D000535:Aluminum
keywords: Aluminum; Amphibian embryo; Evolution; Onto-Evo; Resilience; pH