Retinoid metabolism (LRAT, REH) in the liver and plasma retinoids of bullfrog, Rana catesbeiana, in relation to agricultural contamination

Boily, Monique; Thibodeau, Janik; Bisson, Marjolaine

doi:10.1016/j.aquatox.2008.11.006

Cited by 17 publications

(6 citation statements)

References 30 publications

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“…In modulating the synthesis of RA, the 13cisRA isomer can lead to teratogenic effects without the activation of nuclear receptors or isomerization in atRA. Compared to other isomers, 13cisRA and its metabolites have a higher half-life (Reynolds et al 2003;Armstrong et al 2005), which could explain why we detected the 13cis-4-oxo-RA and not the at-4-oxo-RA metabolite in the bullfrog plasma (this study; Bérubé et al 2005;Boily et al 2009). Spontaneous isomerizations of atRA, 13cisRA and 9cisRA may occur in the presence of compounds having a radical thiol group (Shih et al 1997).…”

Section: Discussioncontrasting

confidence: 51%

“…Under these conditions, the retention time of 13cis-4-oxo-RA was 5.6 min. Compared with synthesized standards described above, no peak of at4-oxo-RA was detected in microsomal extracts, as it was the case in Bérubé et al (2005) and Boily et al (2009).…”

Section: Plasma 13cis-4-oxo-ra Analysismentioning

confidence: 65%

“…All the steps were performed at 0-4°C and according to Boily et al (2009). Microsomes were prepared using 0.5 g of liver tissue homogenized in 2 ml Tris-KCl buffer (0.15 M KCl, 50 mM Tris-HCl, pH 7.4).…”

Section: Microsome Preparationmentioning

confidence: 99%

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Oxidation of retinoic acids in hepatic microsomes of wild bullfrogs Lithobates catesbeianus environmentally-exposed to a gradient of agricultural contamination

et al. 2012

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Agricultural contaminants are suspected of contributing to the increased incidence of deformities and the decline of amphibians populations worldwide. Many authors have further suggested that a retinoid effect could be implicated in teratogenic mechanisms since the reported deformities resemble those caused by abnormal levels of retinoic acid (RA). We previously reported altered retinoid concentrations in male bullfrogs from the Yamaska River basin (Québec, Canada) associated with moderate-to-high agricultural activity, and the findings were consistent with a possible effect on hepatic RA oxidation. An in vitro assay was therefore optimized and hepatic microsomal RA oxidation in bullfrogs was found to be quite different from that of other vertebrates. With either all-transRA (atRA) or 13cisRA as the substrate, the major metabolite generated was at4-oxo-RA. The reaction with 13cisRA as substrate, markedly greater compared with atRA, was enhanced in the presence of a reducing agent and inhibited by cytochrome P450 inhibitors in a dose-dependent manner. Hepatic RA oxidation in male bullfrogs showed significant differences between sites with no clear relationship to a gradient of agricultural activity or 13cis-4-oxo-RA quantified in plasma. In contrast, the in vitro RA oxidation in females increased with the levels of contamination and coincided in vivo with higher plasma 13cis-4-oxo-RA concentration. The levels of circulating 4-oxo-derivatives could be influenced by hepatic RA oxidative metabolism as well as isomerization conditions or RA precursor levels.

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Section: Discussioncontrasting

confidence: 51%

Section: Plasma 13cis-4-oxo-ra Analysismentioning

confidence: 65%

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Oxidation of retinoic acids in hepatic microsomes of wild bullfrogs Lithobates catesbeianus environmentally-exposed to a gradient of agricultural contamination

et al. 2012

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“…Detailed analysis of the fatty acyl composition of retinyl ester in the same study revealed that the two most abundant retinyl ester isoforms in the frog liver were retinyl palmitate and retinyl oleate; thus, the abundance of retinyl ester in the liver and its fatty acyl composition is comparable to mammals and fish [Futterman and Andrew, 1964]. This observation has been confirmed in wild and captive bullfrogs (R. catesbeina), for which retinyl palmitate has also been shown to be the most abundant retinyl ester isoform found in the liver [Tsin et al, 1984;Boily et al, 2009].…”

Section: Vitamin a Metabolism In Amphibians: What We Knowmentioning

confidence: 90%

“…Care should also be taken when interpreting more recent reports of tissue vitamin A levels, with the reader critically assessing the experimental design and analytical methods. A case in point concerns a trio of reports from the TOXEN research center in Quebec, Canada [Berube et al, ; Boily et al, ; Boily et al, ]. In this series of reports, modern HPLC protocols were used to measure vitamin A levels in wild bullfrogs ( Rana catesbeiana ) to assess responses to agricultural contamination.…”

Section: Introductionmentioning

confidence: 99%

Vitamin A (retinoid) metabolism and actions: What we know and what we need to know about amphibians

Clugston

Blaner

2014

Zoo Biology

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Vitamin A status is an important consideration in the health of both wild and captive amphibians. Data concerning whole body vitamin A homeostasis in amphibians are scarce, although these animals have been used as experimental models to study the actions of vitamin A in vision, limb regeneration and embryogenesis. The available data suggest that many aspects of vitamin A biology in amphibians are similar to the canonical characteristics of vitamin A metabolism and actions established in mammals. This is consistent with the evolutionary conservation of these important biological processes. Amphibians must obtain vitamin A in their diet, with captive animals being prone to vitamin A deficiency. There is still much to be learned about vitamin A biology in amphibians that can only be achieved through rigorous scientific research. Improved understanding of amphibian vitamin A biology will aid the conservation of endangered amphibians in the wild, as well as the successful maintenance of ex situ populations.

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Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments

Boily

Sarrasin

Deblois

et al. 2013

Environ Sci Pollut Res

163

105

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In Québec, as observed globally, abnormally high honey bee mortality rates have been reported recently. Several potential contributing factors have been identified, and exposure to pesticides is of increasing concern. In maize fields, foraging bees are exposed to residual concentrations of insecticides such as neonicotinoids used for seed coating. Highly toxic to bees, neonicotinoids are also reported to increase AChE activity in other invertebrates exposed to sub-lethal doses. The purpose of this study was therefore to test if the honey bee's AChE activity could be altered by neonicotinoid compounds and to explore possible effects of other common products used in maize fields: atrazine and glyphosate. One week prior to pollen shedding, beehives were placed near three different field types: certified organically grown maize, conventionally grown maize or non-cultivated. At the same time, caged bees were exposed to increasing sub-lethal doses of neonicotinoid insecticides (imidacloprid and clothianidin) and herbicides (atrazine and glyphosate) under controlled conditions. While increased AChE activity was found in all fields after 2 weeks of exposure, bees close to conventional maize crops showed values higher than those in both organic maize fields and non-cultivated areas. In caged bees, AChE activity increased in response to neonicotinoids, and a slight decrease was observed by glyphosate. These results are discussed with regard to AChE activity as a potential biomarker of exposure for neonicotinoids.

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Retinoid metabolism (LRAT, REH) in the liver and plasma retinoids of bullfrog, Rana catesbeiana, in relation to agricultural contamination

Cited by 17 publications

References 30 publications

Oxidation of retinoic acids in hepatic microsomes of wild bullfrogs Lithobates catesbeianus environmentally-exposed to a gradient of agricultural contamination

Oxidation of retinoic acids in hepatic microsomes of wild bullfrogs Lithobates catesbeianus environmentally-exposed to a gradient of agricultural contamination

Vitamin A (retinoid) metabolism and actions: What we know and what we need to know about amphibians

Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments

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