title: Effects of glyphosate and the glyphosate based herbicides Roundup Original(®) and Roundup Transorb(®) on respiratory morphophysiology of bullfrog tadpoles.
abstract: Glyphosate-based herbicides are widely used in agriculture and are commonly found in water bodies. Roundup Original(®) (RO) contains an isopropylamine glyphosate (GLY) salt containing the surfactant POEA, while Roundup Transorb R(®) (RTR) contains a potassium salt of GLY with unknown surfactants. Both contain different compositions of so-called "inert" ingredients, more toxic than glyphosate. Amphibian tadpoles often experience variations in O2 availability in their aquatic habitats; an ability to tolerate hypoxia can condition their survival and fitness. We evaluated the impacts of sublethal concentrations of GLY (1 mg L(-1)), RO (1 mg L(-1) GLY a.e) and RTR (1 mg L(-1) GLY a.e) on metabolic rate (V·O2 - mLO2 Kg1 h(-1)) of bullfrog tadpoles during normoxia and graded hypoxia, and related this to morphology of their skin, their major site of gas exchange. In control (CT) V·O2 remained unaltered from normoxia until 40 mmHg, indicating a critical O2 tension between 40 and 20 mmHg. GLY significantly reduced V·O2, possibly due to epidermal hypertrophy, which increased O2 diffusion distance to O2 uptake. In contrast, RTR increased V·O2 during hypoxia, indicating an influence of "inert" compounds and surfactants. V·O2 of RO did not differ from CT, suggesting that any increase in V·O2 caused by exposure was antagonized by epidermal hypertrophy. Indeed, all herbicides caused marked alterations in skin morphology, with cell and epithelium wall presenting hyperplasia or hypertrophy and chromatid rupture. In summary, GLY, RO and RTR exert different effects in bullfrog tadpoles, in particular the surfactants and inert compounds appear to influence oxygen uptake.
authors.affiliation: Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, Brazil.
authors.forename: Rafael Zanelli
authors.initials: RZ
authors.lastname: Rissoli
authors.affiliation: Department of Biology, Federal University of São Carlos, Sorocaba, SP, Brazil.
authors.forename: Fabio Camargo
authors.initials: FC
authors.lastname: Abdalla
authors.affiliation: Department of Biology, Federal University of São Carlos, Sorocaba, SP, Brazil.
authors.forename: Monica Jones
authors.initials: MJ
authors.lastname: Costa
authors.affiliation: Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, Brazil.
authors.forename: Francisco Tadeu
authors.initials: FT
authors.lastname: Rantin
authors.affiliation: UMR9190 Centre for Marine Biodiversity Exploitation and Conservation, University of Montpellier, France.
authors.forename: David John
authors.initials: DJ
authors.lastname: McKenzie
authors.affiliation: Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, Brazil. Electronic address: akalinin@ufscar.br.
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Kalinin
mesh_terms: D000818:Animals; D005998:Glycine / Q000031:analogs & derivatives* / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D007814:Larva / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011892:Rana catesbeiana / Q000033:anatomy & histology / Q000378:metabolism; D012867:Skin / Q000187:drug effects / Q000473:pathology; D013501:Surface-Active Agents / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D010100:Oxygen; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D000097797:Glyphosate
keywords: Glyphosate; Hypoxia; Lithobates catesbeianus tadpoles; Oxygen consumption; Respirometry; Skin morphology