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Impact of salt-contaminated freshwater on osmoregulation and tracheal gill function in nymphs of the mayfly Hexagenia rigida.
Nowghani, Fargol; Chen, Chun Chih; Jonusaite, Sima; Watson-Leung, Trudy; Kelly, Scott P; Donini, Andrew.
Afiliación
  • Nowghani F; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada.
  • Chen CC; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada.
  • Jonusaite S; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada; Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, United States.
  • Watson-Leung T; Aquatic Toxicology Unit, Ontario Ministry of the Environment, Conservation and Parks, 125 Resources Road, Etobicoke, ON, M9P 3V6, Canada.
  • Kelly SP; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada.
  • Donini A; Department of Biology, York University, Toronto, ON, M3J 1P3, Canada. Electronic address: adonini@yorku.ca.
Aquat Toxicol ; 211: 92-104, 2019 Jun.
Article en En | MEDLINE | ID: mdl-30954848
The impact of freshwater (FW) salinization on osmoregulation as well as tracheal gill morphology and function was examined in nymphs of the mayfly Hexagenia rigida following exposure to salt contaminated water (SCW, 7.25 g/l NaCl) for a 7-day period. Ionoregulatory homeostasis was perturbed in SCW exposed H. rigida nymphs as indicated by increased hemolymph Na+, K+ and Cl- levels as well as hemolymph pH and water content. Despite this, SCW did not alter gill Na+-K+-ATPase (NKA) or V-type H+-ATPase (VA) activity. In addition, NKA and VA immunolocalization in gill ionocytes did not show alterations in enzyme location or changes in ionocyte abundance. The latter observation was confirmed using scanning electron microscopy (SEM) to examine exposed tracheal gill ionocyte numbers. Ionocyte surface morphometrics also revealed that SCW did not change individual ionocyte surface area or ionocyte fractional surface area. Nevertheless, analysis of Na+ movement across the tracheal gill of mayfly nymphs using scanning ion-selective electrode technique indicated that FW nymphs acquired Na+ from surrounding water, while tracheal gills of SCW nymphs had the capacity to secrete Na+. Because Na+ secretion across the gill of SCW-exposed animals occurred in the absence of any change in (1) NKA and VA activity or (2) ionocyte numbers/surface exposure, it was reasoned that Na+ movement across the gill of SCW animals may be occurring, at least in part, through the paracellular pathway. The ultrastructure of tracheal gill septate junctions (SJs) supported this idea as they exhibited morphological alterations indicative of a leakier pathway. Data provide a first look at alterations in osmoregulatory mechanisms that allow H. rigida nymphs to tolerate sub-lethal salinization of their surroundings.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Contaminantes Químicos del Agua / Cloruro de Sodio / Osmorregulación / Ephemeroptera / Agua Dulce / Branquias Límite: Animals Idioma: En Revista: Aquat Toxicol Asunto de la revista: BIOLOGIA / TOXICOLOGIA Año: 2019 Tipo del documento: Article País de afiliación: Canadá Pais de publicación: Países Bajos
Texto completo
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Contaminantes Químicos del Agua / Cloruro de Sodio / Osmorregulación / Ephemeroptera / Agua Dulce / Branquias Límite: Animals Idioma: En Revista: Aquat Toxicol Asunto de la revista: BIOLOGIA / TOXICOLOGIA Año: 2019 Tipo del documento: Article País de afiliación: Canadá Pais de publicación: Países Bajos