TY - JOUR
T1 - Age-altered susceptibility in hexavalent chromium-exposed Daphnia schodleri (Anomopoda: Daphniidae)
T2 - Integrated Biomarker Response implementation
AU - Arzate-Cárdenas, Mario Alberto
AU - Martínez-Jerónimo, Fernando
N1 - Funding Information:
M.A. Arzate-Cárdenas was supported by a CONACYT scholarship (No. 205561) and also was a fellow of the Programa Institucional de Formación de Investigadores (PIFI) de la Comisión de Operación y Fomento de Actividades Académicas (COFAA). F. Martínez-Jerónimo thanks the Sistema de Estímulo al Desempeño de los Investigadores (EDI) and the Comisión de Operación y Fomento de Actividades Académicas (COFAA) of the I.P.N. for the support given. Also thanks to Ms. Ingrid Mascher for editorial assistance and review of the English-written manuscript. Finally, we thank the two anonymous reviewers whose comments and critical evaluation helped to improve this manuscript.
PY - 2011/10
Y1 - 2011/10
N2 - Daphnia schodleri is a naturally occurring cladoceran in Mexican freshwater bodies and its relative big size and short life cycle allow its use in toxicological bioassays. Generally, life stages at opposite sides of a normal distribution are considered to be the most susceptible and/or sensitive because of several sub-individual level processes, such as ageing, in which antioxidant activity decreases and reactive oxygen species (ROS) cannot be totally neutralized. Most aquatic populations are structured by organisms of different ages, in which physiological and biochemical responses differ (in magnitude) from each other. According to these statements, seven age groups of D. schodleri (0, 3, 5, 7, 14, 21, and 28 d) were exposed to Cr (VI) in both acute and non-lethal bioassays. Results from acute bioassays were used to estimate the chromium LC 50 values for every age group, which ranged from 0.12 to 0.61mgL -1, with a normal pattern distribution. Antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) was assessed in organisms exposed to two sublethal Cr(VI) concentrations (0.032 and 0.0064mgL -1). Results showed that neonates' antioxidant activity increased with respect to their controls; nevertheless, the same pattern was not seen in the other age groups. Moreover, GPx activities followed a decreasing pattern with respect to their control groups in organisms 3-d and older. In addition, GR activities were barely modified by chromium exposure of neonates, but not in the other age groups; CAT was only modified in younger daphnids. Once the biomarker responses were normalized, it was possible to observe that enzyme participation differed during the life cycle of this cladoceran and, as a result of their decreasing antioxidant activity, relatively old organisms could have lower capability to deal with pro-oxidant toxicants such as Cr(VI).
AB - Daphnia schodleri is a naturally occurring cladoceran in Mexican freshwater bodies and its relative big size and short life cycle allow its use in toxicological bioassays. Generally, life stages at opposite sides of a normal distribution are considered to be the most susceptible and/or sensitive because of several sub-individual level processes, such as ageing, in which antioxidant activity decreases and reactive oxygen species (ROS) cannot be totally neutralized. Most aquatic populations are structured by organisms of different ages, in which physiological and biochemical responses differ (in magnitude) from each other. According to these statements, seven age groups of D. schodleri (0, 3, 5, 7, 14, 21, and 28 d) were exposed to Cr (VI) in both acute and non-lethal bioassays. Results from acute bioassays were used to estimate the chromium LC 50 values for every age group, which ranged from 0.12 to 0.61mgL -1, with a normal pattern distribution. Antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) was assessed in organisms exposed to two sublethal Cr(VI) concentrations (0.032 and 0.0064mgL -1). Results showed that neonates' antioxidant activity increased with respect to their controls; nevertheless, the same pattern was not seen in the other age groups. Moreover, GPx activities followed a decreasing pattern with respect to their control groups in organisms 3-d and older. In addition, GR activities were barely modified by chromium exposure of neonates, but not in the other age groups; CAT was only modified in younger daphnids. Once the biomarker responses were normalized, it was possible to observe that enzyme participation differed during the life cycle of this cladoceran and, as a result of their decreasing antioxidant activity, relatively old organisms could have lower capability to deal with pro-oxidant toxicants such as Cr(VI).
KW - Acute toxicity
KW - Antioxidant enzymes
KW - Biomarker
KW - Cladoceran
KW - Life cycle
UR - http://www.scopus.com/inward/record.url?scp=80052516795&partnerID=8YFLogxK
U2 - 10.1016/j.aquatox.2011.08.006
DO - 10.1016/j.aquatox.2011.08.006
M3 - Artículo
C2 - 21906533
SN - 0166-445X
VL - 105
SP - 528
EP - 534
JO - Aquatic Toxicology
JF - Aquatic Toxicology
IS - 3-4
ER -