Metals and organochlorine pesticides in caudal scutes of crocodiles from Belize and Costa Rica

Rainwater, Thomas R.; Wu, Ted H.; Finger, Adam G.; Cañas, Jaclyn E.; Yu, Lu; Reynolds, Kevin D.; Coimbatore, Gopal; Barr, Brady; Platt, Steven G.; Cobb, George P.; Anderson, Todd A.; McMurry, Scott T.

doi:10.1016/j.scitotenv.2006.11.010

Cited by 92 publications

(44 citation statements)

References 43 publications

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“…They may be additionally exposed to the demethylated metabolites through ingestion of MXC-exposed prey organisms that have biotransformed MXC. Recent studies have reported parent MXC concentrations of 0.7 ng/g in seafood from Southern China (Guo et al, 2007), between <0.35 ng/g (limit of detection) and 2 ng/g in freshwater fish captured in the Colorado river (Hinck et al, 2007), between 8 and 17 ng/g in alligator eggs from central Florida lakes (Rauschenberger et al, 2007) and 534 ng/g in fat from crocodile scute in Costa Rica (Rainwater et al, 2007). MXC was found in 5 of 36 soil samples taken from agricultural areas in British Columbia, and the average MXC concentration in these samples was 0.23 mg/ kg (Wan et al, 2005).…”

Section: Comparisons Of Conjugation and Demethylation Pathwaysmentioning

confidence: 99%

Glucuronidation and sulfonation, in vitro, of the major endocrine-active metabolites of methoxychlor in the channel catfish, Ictalurus punctatus, and induction following treatment with 3-methylcholanthrene

2008

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The organochlorine pesticide, methoxychlor (MXC), is metabolized in animals to phenolic monoand bis-demethylated metabolites (OH-MXC and HPTE respectively) that interact with estrogen receptors and may be endocrine disruptors. The phase II detoxication of these compounds will influence the duration of action of the estrogenic metabolites, but has not been investigated extensively. In this study, the glucuronidation and sulfonation of OH-MXC and HPTE were investigated in subcellular fractions of liver and intestine from untreated, MXC-treated and 3-methylcholanthrene (3-MC)-treated channel catfish, Ictalurus punctatus. MXC-treated fish were given i.p. injections of 2 mg MXC/kg daily for 6 days and sacrificed 24 hr after the last dose. The 3-MC treatment was a single 10 mg/kg i.p. dose 5 days prior to sacrifice. In hepatic microsomes from control fish, the V max value (mean ± S.D., n=4) for glucuronidation of OH-MXC was 270 ± 50 pmol/ min/mg protein, higher than found for HPTE (110 ± 20 pmol/min/mg protein). For each substrate, the V max values observed in intestinal microsomes were approximately twice those found in the liver. The K m values for OH-MXC and HPTE glucuronidation in control liver were not significantly different and were 0.32 ± 0.04 mM for OH-MXC and 0.26 ± 0.06 mM for HPTE. The K m for the co-substrate, UDPGA, was higher in liver (0.28 ± 0.09 mM) than intestine (0.04 ± 0.02 mM). Treatment with 3-MC but not MXC increased the V max for glucuronidation in liver and intestine. Glucuronidation was a more efficient pathway than sulfonation for both substrates, in both tissues. The V max values for sulfonation of OH-MXC and HPTE respectively in liver cytosol were 7 ± 3 and 17 ± 4 pmol/min/mg protein and in intestinal cytosol were 13 ± 3 and 30 ± 5 pmol/min/mg protein. Treatment with 3-MC but not MXC increased rates of sulfonation of OH-MXC and HPTE and the model substrate, 3-hydroxy-benzo(a)pyrene in both intestine and liver. Comparison of the kinetics of the conjugation pathways with those published for the demethylation of MXC showed that formation of the endocrine-active metabolites was more efficient than either conjugation pathway. Residues of OH-MXC and HPTE were detected in extracts of liver microsomes from MXC-treated fish. This work showed that although OH-MXC and HPTE could be eliminated by glucuronidation and sulfonation, the phase II pathways were less efficient than the phase I pathway leading to formation of these endocrine-active metabolites.

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Section: Comparisons Of Conjugation and Demethylation Pathwaysmentioning

confidence: 99%

Glucuronidation and sulfonation, in vitro, of the major endocrine-active metabolites of methoxychlor in the channel catfish, Ictalurus punctatus, and induction following treatment with 3-methylcholanthrene

2008

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“…Multiple studies (Twinning et al 1999;Jeffree et al 2001;Rainwater et al 2007) report background or elevated Pb concentrations in the flesh and osteoderms of several species in the wild, but information about the clinical symptoms and reproductive effects of Pb toxicosis is mainly limited to studies on captive crocodilians fed meat contaminated with Pb shot (Camus et al 1998;Hammerton et al 2003;Lance et al 2006). One experimental study of four juvenile saltwater crocodiles (Crocodylus porosus) dosed with Pb shot suggested a half-life for Pb in blood of about 3.4 days (Hammerton et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Blood lead concentrations in free-ranging Nile crocodiles (Crocodylus niloticus) from South Africa

et al. 2016

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Generally crocodilians have received little attention with regard to the effects of lead toxicity despite their trophic status as apex, generalist predators that utilize both aquatic and terrestrial habitats, thereby exposing them to a potentially wide range of environmental contaminants. During July-October 2010 we collected whole blood from 34 sub-adult and adult free-ranging Nile crocodiles (Crocodylus niloticus) from three separate populations in northeastern South Africa in order to analyze their blood lead concentrations (BPb). Concentrations ranged from below detectability (<3 μg/dL, n = 8) to 960 μg/dL for an adult male at the Lake St Lucia Estuary. Blood lead concentrations averaged 8.15 μg/dL (SD = 7.47) for females and 98.10 μg/dL (SD = 217.42) for males. Eighteen individuals (53 %) had elevated BPbs (≥10 μg/dL). We assessed 12 general linear models using Akaike's Information Criterion (AIC) and found no significant statistical effects among the parameters of sex, crocodile size and population sampled. On average, crocodiles had higher BPbs at Lake St Lucia than at Ndumo Game Reserve or Kosi Bay, which we attribute to lead sinker ingestion during normal gastrolith acquisition. No clinical effects of lead toxicosis were observed in these crocodiles, even though the highest concentration (960 μg/dL) we report represents the most elevated BPb recorded to date for a free-ranging vertebrate. Although we suggest adult Nile crocodiles are likely tolerant of elevated Pb body burdens, experimental studies on other crocodilian species suggest the BPb levels reported here may have harmful or fatal effects to egg development and hatchling health. In light of recent Nile crocodile nesting declines in South Africa we urge further BPb monitoring and ecotoxicology research on reproductive females and embryos.

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“…En el caso de los sitios donde no se detectaron los elementos, el valor fue sustituido por el equivalente a la mitad del límite de detección del método para el elemento correspondiente (Rainwater et al, 2007).…”

Section: Análisis Estadísticosunclassified

Metales pesados en suelos y sedimentos de la zona cañera del sur de Quintana Roo, México

et al. 2017

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In order to determine the heavy metals content and distribution in an area cultivated with sugarcane in the Río INTRODUCCIÓNMéxico se encuentra dividido en 37 regiones hidrológicas que a su vez se agrupan en 13 regiones hidrológico-administrativas. Las aguas del estado de Quintana Roo se ubican en la región hidrológica-Metales pesados en suelos y sedimentos de la zona cañera del sur de Quintana Roo, México

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Metals and organochlorine pesticides in caudal scutes of crocodiles from Belize and Costa Rica

Cited by 92 publications

References 43 publications

Glucuronidation and sulfonation, in vitro, of the major endocrine-active metabolites of methoxychlor in the channel catfish, Ictalurus punctatus, and induction following treatment with 3-methylcholanthrene

Glucuronidation and sulfonation, in vitro, of the major endocrine-active metabolites of methoxychlor in the channel catfish, Ictalurus punctatus, and induction following treatment with 3-methylcholanthrene

Blood lead concentrations in free-ranging Nile crocodiles (Crocodylus niloticus) from South Africa

Metales pesados en suelos y sedimentos de la zona cañera del sur de Quintana Roo, México

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