Molecular Cloning and Sequence Analysis of cDNAs Coding for 3-Methylcholanthrene-Inducible Cytochromes P450 in Xenopus laevis Liver

Fujita, Yoshiaki; Ohi, Hiroshi; Murayama, Nobuhiro; Saguchi, Ken-ichi; Higuchi, Shigesada

doi:10.1006/abbi.1999.1425

Cited by 26 publications

(19 citation statements)

References 25 publications

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“…Whereas Innan (2003) frog shared a more recent common ancestor with birds and mammals, it is tempting to speculate that the CYP1A1 locus is ancestral. There is no evidence of a second CYP1A gene elsewhere in the X. tropicalis genome, and the presence of two CYP1A genes in X. laevis (Fujita et al, 1999) is probably an artifact of tetraploidy in that species. Thus, it is unlikely that this interpretation could be complicated by a CYP1A paralog in X. tropicalis.…”

Section: Discussionmentioning

confidence: 94%

A Revised Evolutionary History of the CYP1A Subfamily: Gene Duplication, Gene Conversion, and Positive Selection

Goldstone

Stegeman

2006

J Mol Evol

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Running header: Recombination and selection in tetrapod CYP1AsKey words: Cytochrome P450, gene conversion, gene duplication, chicken, mammalian Abbreviations:Page 1 of 32 JME-2005-00134 ABSTRACTMembers of cytochrome P450 subfamily 1A (CYP1As) are involved in detoxification and bioactivation of common environmental pollutants. Understanding the functional evolution of these genes is essential to predicting and interpreting species differences in sensitivity to toxicity by such chemicals. The CYP1A gene subfamily comprises a single ancestral representative in most fish species and two paralogs in higher vertebrates, including birds and mammals.Phylogenetic analysis of complete coding sequences suggests that mammalian and bird paralog pairs (CYP1A1/2 and CYP1A4/5, respectively) are the result of independent gene duplication events. However, comparison of vertebrate genome sequences revealed that CYP1A genes lie within an extended region of conserved fine-scale synteny, suggesting that avian and mammalian CYP1A paralogs share a common genomic history. Algorithms designed to detect recombination between nucleotide sequences indicate that gene conversion has homogenized most of the length of the chicken CYP1A genes, as well as the 5' end of mammalian CYP1As.Together, these data indicate that avian and mammalian CYP1A paralog pairs resulted from a single gene duplication event and that extensive gene conversion is responsible for the exceptionally high degree of sequence similarity between CYP1A4 and CYP1A5. Elevated nonsynonymous/synonymous substitution ratios within a putatively unconverted stretch of ~250 bp suggests that positive selection may have reduced the effective rate of gene conversion in this region, which contains two substrate recognition sites. This work significantly alters our understanding of functional evolution in the CYP1A subfamily, suggesting that gene conversion and positive selection have been the dominant processes of sequence evolution.

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Section: Discussionmentioning

confidence: 94%

A Revised Evolutionary History of the CYP1A Subfamily: Gene Duplication, Gene Conversion, and Positive Selection

Goldstone

Stegeman

2006

J Mol Evol

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“…Fujita et al 29) reported molecular cloning and sequence analysis of cDNAs coding for 3-methylcholanthrene-inducible CYP1A isoform in X. laevis liver. In contrast, induction of hepatic CYP2B by phenobarbital (PB) has been reported in semi-aquatic frog (Rana pipiens).…”

Section: Resultsmentioning

confidence: 99%

Effects of Nonylphenol and Triclosan on Production of Plasma Vitellogenin and Testosterone in Male South African Clawed Frogs (Xenopus laevis)

Matsumura

Ishibashi

Hirano

et al. 2005

Biological & Pharmaceutical Bulletin

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Recently, a number of studies have been performed worldwide to examine endocrine-disrupting chemicals (EDCs) and their interactions with the development and function of various systems in animals and humans.1-3) Among these EDCs, alkylphenol polyethoxylate non-ionic surfactants are used in the manufacture of cleaning agents, cosmetics and food products, as well as in plastic polymerization processes. Nonylphenol ethoxylates have predominantly been used, amounting to about 80% of the production of alkylphenol surfactants. In a recent study, nonylphenol (NP) had significant effects on the reproductive potential of medaka (Oryzias latipes) at concentrations as low as 17.7 mg/l, 4) and 50% of the male fish in the 50 mg/l treatment and 86% of the males in the 100 mg/l treatment developed testis-ova, an intersex condition characterized by both testicular and ovarian tissue in the gonad. 5) On the other hand, triclosan (TCS, 2,4,4Ј-trichloro-2Ј-hydroxydiphenyl ether) is widely used as an antibacterial agent in liquid toothpaste, soap, shampoo, and cosmetics, and is frequency found in wastewater effluent. Water samples collected near the outfall of a wastewater treatment plant in Rhode Island, U.S.A., showed 10-20 mg/l of TCS in the effluent and 80-100 mg/g of TCS in the sediment.6,7) Our previous study suggests that TCS has high toxicity on the early life stages of medaka, and that the metabolite of TCS may be a weak estrogenic compound in male medaka but with no adverse effect on reproductive success (such as fecundity and fertility) and offspring. 8) Moreover, Hanioka et al. 9,10) reported that 7-benzyloxyresorufin Odebenzylase (BROD) and 7-pentoxyresorufin O-depentylase (PROD) activities, which are associated with CYP2B1 activity, were remarkably induced by all doses of TCS in rats. Their results suggested that TCS induces the P450 isoforms of the CYP2B subfamily in the rat liver, and that the induced P450 isozymes were closely related to the toxicity of TCS or its chlorinated derivatives. However, there is no information about the effects of these chemicals on the hormonally responses of amphibian. 11)The South African clawed frog (Xenopus laevis) is sensitive to environmental chemicals as it spends all the life stages (egg, larva, and adulthood) in water. Hayes et al. 12) examined the effects of atrazine on sexual development in X. laevis, and reported that atrazine (Ͼ or ϭ0.1 mg/l) induced hermaphroditism and demasculinized the larynx of exposed males (Ͼ or ϭ1.0 mg/l), and male X. laevis suffered a 10-fold decrease in testosterone levels when exposed to 25 mg/l atrazine. Therefore, in the present study, we used X. laevis as a test organism, and investigated the effects of NP and TCS on production of plasma vitellogenin (Vg, egg yolk protein precursor), steroid hormone testosterone (T) synthesis, and hepatic CYP1A and CYP2B, as measured by the ethoxyresorufin O-deethylase (EROD) or PROD activities in male X. laevis. To our knowledge, this is first study on the effect of TCS in male X. laevis. MATERIALS AND MET...

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“…67) In contrast, no corresponding band was detected in the embryo 8 days post-fertilization, but the enzyme was induced by 1-day exposure to BaP solution. Fujita et al 68) have demonstrated induction of the hepatic enzyme (ca. 54 kDa), detected by the same antisera as above, in the adult females by injection of 3MC.…”

Section: Relevant Enzymesmentioning

confidence: 99%

Bioconcentration and metabolism of pesticides and industrial chemicals in the frog

Katagi

Ose

2014

J. Pestic. Sci.

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Exposure to pesticide residues is claimed to be one of the possible causes of frog decline. Knowledge of basic information on the uptake, metabolism and depuration processes of pesticides in the frog is needed to understand the relationship between exposure and toxic effects from their actual body burden, together with their bioconcentration. The hydrophobicity of pesticides and industrial chemicals was one of the most important factors controlling bioconcentration, similarly to fish, when frogs are exposed to contaminated water. Skin absorption was also a key route in the uptake process especially in the adult frog. The metabolic profiles in the frog, mainly examined by an intraperitoneal injection technique, were common to other aquatic species without any frog-specific transformation reaction. The effects of developmental stage, sex, species and environmental factors such as temperature were observed for bioconcentration and metabolism.

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Molecular Cloning and Sequence Analysis of cDNAs Coding for 3-Methylcholanthrene-Inducible Cytochromes P450 in Xenopus laevis Liver

Cited by 26 publications

References 25 publications

A Revised Evolutionary History of the CYP1A Subfamily: Gene Duplication, Gene Conversion, and Positive Selection

A Revised Evolutionary History of the CYP1A Subfamily: Gene Duplication, Gene Conversion, and Positive Selection

Effects of Nonylphenol and Triclosan on Production of Plasma Vitellogenin and Testosterone in Male South African Clawed Frogs (Xenopus laevis)

Bioconcentration and metabolism of pesticides and industrial chemicals in the frog

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