Differential expression of two cinnamate 4-hydroxylase genes in 'Valencia' orange (Citrus sinensis Osbeck)

Two different full-length cDNAs for cinnamate 4-hydroxylase (C4H1 and C4H2) were isolated from Citrus sinensis Osbeck cv. Valencia libraries. C4H1 (1708 bp) and C4H2 (1871 bp) share only 65% identity on nucleotide and 66% identity on the amino acid level, respectively. C4H1 is most homologous to a cinnamate 4-hydroxylase sequence from French bean (Phaseolus vulgaris), but codes for a unique N-terminus. C4H2 shows highest similarity to a poplar (Populus kitakamiensis) sequence, but also shows a unique N-terminus. The two genes are expressed differentially in orange flavedo, C4H2 is constitutive, C4H1 is wound-induced. In competitive RT-PCR, the mRNA for both genes in wounded and untreated tissue was quantified. C4H1 is strongly wound-inducible from `not detectable' to about 35 fg mRNA per 50 ng total RNA 8 h after wounding. The first detectable C4H1 mRNA was found 4 h after wounding. After reaching peak levels 4 h later the levels slightly declined, but stayed elevated until the end of the experiment (48 h). C4H2 is expressed 3–10 times higher than wound-induced C4H1 even in the control sample; wounding transiently increases the level of expression another 2–3 times. The existence of different N-termini and their effects on the possible role of both genes in phenylpropanoid pathways is discussed.     

Introduction of sense constructs of cinnamate 4-hydroxylase (CYP73A24) in transgenic tomato plants shows opposite effects on flux into stem lignin and fruit flavonoids

Understanding regulation of phenolic metabolism underpins attempts to engineer plants for diverse properties such as increased levels of antioxidant flavonoids for dietary improvements or reduction of lignin for improvements to fibre resources for industrial use. Previous attempts to alter phenolic metabolism at the level of the second enzyme of the pathway, cinnamate 4-hydroxylase have employed antisense expression of heterologous sequences in tobacco. The present study describes the consequences of homologous sense expression of tomato CYP73A24 on the lignin content of stems and the flavonoid content of fruits. An extensive number of lines were produced and displayed four developmental variants besides a normal phenotype. These aberrant phenotypes were classified as dwarf plants, plants with distorted (curly) leaves, plants with long internodes and plants with thickened waxy leaves. Nevertheless, some of the lines showed the desired increase in the level of rutin and naringenin in fruit in a normal phenotype background. However this could not be correlated directly to increased levels of PAL and C4H expression as other lines showed less accumulation, although all lines tested showed increases in leaf chlorogenic acid which is typical of Solanaceous plants when engineered in the phenylpropanoid pathway. Almost all transgenic lines analysed showed a considerable reduction in stem lignin and in the lines that were specifically examined, this was correlated with partial sense suppression of C4H. Although not the primary purpose of the study, these reductions in lignin were amongst the greatest seen in plants modified for lignin by manipulation of structural genes. The lignin showed higher syringyl to coniferyl monomeric content contrary to that previously seen in tobacco engineered for downregulation of cinnamate 4-hydroxylase. These outcomes are consistent with placing CYP73A24 more in the lignin pathway and having a role in flux control, while more complex regulatory processes are likely to be involved in flavonoid and chlorogenic acid accumulation.     

Molecular cloning of the cDNA encoding a stress-inducible protein phosphatase 1 (PP1) catalytic subunit from French bean (Phaseolus vulgaris L.)

A cDNA showing high sequence similarity (>70%) to plant protein phosphatase 1 catalytic subunit variants from other species has been isolated from a cDNA library derived from mRNAs expressed in elicitor-treated suspension-cultured cells. The clone appears to be a near full-length 1431 bp with a 172 bp 5-untranslated region and a 317 bp 3-untranslated region. The open reading frame, determined by sequence similarity, codes for a protein with predicted M _r of 35552. Alternatively an ATG situated to the 5 end of the putative start site would increase the protein size by 6 amino acids.The mRNA for Pvpp1 was shown to be rapidly induced by elicitor treatment of suspension-cultured cells of French bean. The cloned cDNA represents one of the few examples of a gene product that is probably involved in dephosphorylation events arising after the initial responses to biotic stress.Abbreviations PAL phenylalanine ammonia-lyase - PP1 protein phosphatase 1 - Pvpp1 Phaseolus vulgaris protein phosphatase 1     

The use of immunological methods to study the activity of cellulase isozymes (B 1:4 glucan 4-glucan hydrolase) in bean leaf abscission

Abstract The changes in the levels of two different isozymes of cellulase (EC 3.2.1.4) have been followed during the abscission of the primary leaves of bean (Phaseolus vulgaris c.v. Red Kidney), using antibodies raised against the 9.5 form of the enzyme. Data from both radioimmune and direct assay show that the 9.5 form of cellulase is undetectable prior to the induction of abscission. After a 12 h lag this isozyme increases in activity, the increase preceding a decrease in integrity of the abscission zone cell walls. The results are consistent not only with the view that this specific isozyme is involved in wall hydrolysis but also with previous data which showed that cellulase is synthesized ‘de novo’. The 4.5 isozyme of cellulase is more widely spread throughout the plant, being most active in young tissues. During abscission the activity of this isozyme in the abscission layer falls and consequently it is not thought to be involved directly in the abscission process.     

Rapid changes in oxidative metabolism as a consequence of elicitor treatment of suspension-cultured cells of French bean (Phaseolus vulgaris L.)

Stressed plant cells often show increased oxygen uptake which can manifest itself in the transient production of active oxygen species, the oxidative burst. There is a lack of information on the redox status of cells during the early stages of biotic stress. In this paper we measure oxygen uptake and the levels of redox intermediates NAD/NADH and ATP and show the transient induction of the marker enzyme for redox stress, alcohol dehydrogenase. Rapid changes in the redox potential of elicitor-treated suspension cultures of French bean cells indicate that, paradoxically, during the period of maximum oxygen uptake the levels of ATP and the NADH/NAD ratio fall in a way that indicates the occurrence of stress in oxidative metabolism. This period coincides with the maximum production of active oxygen species particularly H₂O₂. The cells recover and start producing ATP immediately upon the cessation of H₂O₂ production. This indicates that the increased O₂ uptake is primarily incorporated into active O₂ species. A second consequence of these changes is probably a transient compromising of the respiratory status of the cells as indicated in expression of alcohol dehydrogenase. Elicitor-induced bean ADH was purified to homogeneity and the M_r 40 000 polypeptide was subjected to amino acid sequencing. 15% of the whole protein was sequenced from three peptides and was found to have nearly 100% sequence similarity to the amino acid sequence for pea ADH1 (PSADH1). The cDNA coding for the pea enzyme was used to demonstrate the transient induction of ADH mRNA in elicitor-treated bean cells. Enzyme activity levels also increased transiently subsequently. Increased oxygen uptake has previously been thought to be associated with provision of energy for the changes in biosynthesis that occur rapidly after perception of the stress signal. However the present work shows that this rapid increase in oxygen uptake as a consequence of elicitor action is not wholly associated with respiration.     

桔小实蝇CYP4D46的克隆及其组织特异性表达研究

从桔小实蝇Bactrocera dorsalis(Hendel)成虫体内提取总RNA,利用RT-PCR和cDNA末端快速扩增技术获得了一个新的细胞色素P450基因cDNA序列全长.该基因经细胞色素P450基因命名委员会命名为CYP4D46(Gen-Bank登录号:GU292422),其cDNA全长为1717 bp,包含1530 bp的完整开放阅读框(ORF),编码510个氨基酸,理论分子量约为58.40 kD,等电点为8.82.系统发育分析表明该基因与昆虫第4家族P450基因具有较高的同源性.实时定量PCR分析发现,CYP4D46基因在脂肪体中的相对表达量较高,分别是马氏管和中肠内的756倍和60倍,说明CYP4D46可能与脂肪体的重要生理功能相关.     

Cinnamic acid 4-hydroxylase mechanism-based inactivation by psoralen derivatives: cloning and characterization of a C4H from a psoralen producing plant-Ruta graveolens-exhibiting low sensitivity to psoralen inactivation

Cinnamate 4-hydroxylase (C4H, EC 1.14.13.11) complete cDNA was cloned from the leaves of Ruta graveolens, a psoralen producing plant. The recombinant enzyme (classified CYP73A32) was expressed in Saccharomyces cerevisiae. Mechanism-based inactivation was investigated using various psoralen derivatives. Only psoralen and 8-methoxypsoralen were found to inactivate C4H. The inactivation was dependent on the presence of NADPH, time of pre-incubation, and inhibitor concentration. Inactivation stoichiometry was 0.9 (+/-0.2) for CYP73A1 and 1.1 (+/-0.2) for CYP73A32. SDS-PAGE analysis demonstrated that [3H]psoralen was irreversibly bound to the C4H apoprotein. K(i) and k(inact) for psoralen and 8-methoxypsoralen inactivation on the two C4H revealed a lower sensitivity for CYP73A32 compared to CYP73A1. Inactivation kinetics were also determined for CYP73A10, a C4H from another furocoumarin-producing plant, Petroselinum crispum. This enzyme was found to behave like CYP73A32, with a weak sensitivity to psoralen and 8-MOP inactivation. Cinnamic acid hydroxylation is a key step in the biosynthesis of phenylpropanoid compounds, psoralen derivatives included. Our results suggest a possible evolution of R. graveolens and P. crispum C4H that might tolerate substantial levels of psoralen derivatives in the cytoplasmic compartment without a depletive effect on C4H and the general phenylpropanoid metabolism.     

Antisense and sense expression of cDNA coding for CYP73A15, a class II cinnamate 4-hydroxylase, leads to a delayed and reduced production of lignin in tobacco.

A number of plant species contain the class II of genes encoding the cytochrome P450, CYP73, the cognate protein of which cinnamic acid 4-hydroxylase, is the second enzyme of the phenylpropanoid pathway. In order to begin to determine possible functionality, tobacco has been transformed with a truncated French bean class II cinnamate hydroxylase (CYP73A15) in the sense and antisense orientations. Signals for C4H protein could be detected in vascular tissue from wild-type plants using heterologous probes. The transformed plants showed a normal phenotype, even though detectable C4H protein was much reduced in tissue prints. Young propagated transformants displayed a range of reduced C4H activities, as well as either reduced or no phloroglucinol-stainable lignin. However, all mature tobacco plants showed the accumulation of lignin, even though its deposition was apparently delayed. This was not due to induction of tyrosine ammonia-lyase activity, which was not detected, but instead it is presumed due to sufficient C4H residual activity. Analysis of the lignin content of the plants showed reductions of up to 30% with a slightly reduced syringyl to guaiacyl ratio as compared to wild type. This reduction level was favourable in comparison with some other targets in the lignification pathway that have been manipulated including that of class I cinnamate 4-hydroxylase. It is proposed that the class II cinnamate 4-hydroxylase might also function in lignification in a number of species including French bean and tobacco, based on these data.     

Cloning and expression of a gene encoding a root specific nitrate reductase in bean (Phaseolus vulgaris)

A structural gene encoding nitrate reductase (NR) in the legume Phaseolus vulgaris cv. Saxonia has been cloned and sequenced. The NR gene encodes a protein of 881 amino acids with a MW of 99.2 kDa. The coding sequence is interrupted by three introns, which are located in the molybdopterin cofactor binding domain. In the flanking regions the signals of a functional eukaryotic gene are present. The gene is the smallest NR gene so far identified in higher plants. Comparison to other NRs shows homology ranging from 65 to 74% at the amino acid level. The similarity is highest for the three functional domains, and lowest in the N-terminal end of the protein. mRNA studies demonstrate that the gene is nitrate inducible and expressed exclusively in the roots of bean. Southern blot analysis indicates the presence of a second NR gene in bean. This gene may encode a NR enzyme expressed in leaves.     

CYP330A1 and CYP4C39 enzymes in the shore crab Carcinus maenas: sequence and expression regulation by ecdysteroids and xenobiotics

Cytochrome P450 enzymes (CYP enzymes) catalyse important metabolic reactions of exogenous and endogenous substrates, including steroid hormones. Here, we report the first two CYP sequences from the shore crab, Carcinus maenas. Two complete cDNAs isolated from crab hepatopancreas encode CYP enzymes named CYP330A1, the first member of a new family, and CYP4C39. CYP330A1 is closest related to members of the CYP2 family (37.3% identical to mouse CYP2J6) and CYP4C39 is most identical to crayfish CYP4C15 (59.5%). CYP330A1 gene expression was induced in hepatopancreas of male green intermoult crabs by ecdysone and ponasterone A, but also by benzo(a)pyrene and phenobarbital. CYP330A1 induction was not observed in red crabs. The present results indicate that the CYP330A1 enzyme may be involved in ecdysteroid metabolism, presumably catabolism, and in the detoxification of environmental pollutants. Ecdysteroids or xenobiotics did not affect CYP4C39 gene expression. The fact that both ecdysteroids and xenobiotics affect CYP330A1 gene expression indicates that mutual interactions between chemical exposures and endocrine functions may exist in the shore crab.     

Cloning of three A-type cytochromes P450, CYP71E1, CYP98, and CYP99 from Sorghum bicolor (L.) Moench by a PCR approach and identification by expression in Escherichia coli of CYP71E1 as a multifunctional cytochrome P450 in the biosynthesis of the cyanogenic glucoside dhurrin

A cDNA encoding the multifunctional cytochrome P450, CYP71E1, involved in the biosynthesis of the cyanogenic glucoside dhurrin from Sorghum bicolor (L.) Moench was isolated. A PCR approach based on three consensus sequences of A-type cytochromes P450 – (V/I)KEX(L/F)R, FXPERF, and PFGXGRRXCXG – was applied. Three novel cytochromes P450 (CYP71E1, CYP98, and CYP99) in addition to a PCR fragment encoding sorghum cinnamic acid 4-hydroxylase were obtained.Reconstitution experiments with recombinant CYP71E1 heterologously expressed in Escherichia coli and sorghum NADPH–cytochrome P450–reductase in L--dilaurylphosphatidyl choline micelles identified CYP71E1 as the cytochrome P450 that catalyses the conversion of p-hydroxyphenylacetaldoxime to p-hydroxymandelonitrile in dhurrin biosynthesis. In accordance to the proposed pathway for dhurrin biosynthesis CYP71E1 catalyses the dehydration of the oxime to the corresponding nitrile, followed by a C-hydroxylation of the nitrile to produce p-hydroxymandelonitrile. In vivo administration of oxime to E. coli cells results in the accumulation of the nitrile, which indicates that the flavodoxin/flavodoxin reductase system in E. coli is only able to support CYP71E1 in the dehydration reaction, and not in the subsequent C-hydroxylation reaction.CYP79 catalyses the conversion of tyrosine to p-hydroxyphenylacetaldoxime, the first committed step in the biosynthesis of the cyanogenic glucoside dhurrin. Reconstitution of both CYP79 and CYP71E1 in combination with sorghum NADPH-cytochrome P450–reductase resulted in the conversion of tyrosine to p-hydroxymandelonitrile, i.e. the membranous part of the biosynthetic pathway of the cyanogenic glucoside dhurrin. Isolation of the cDNA for CYP71E1 together with the previously isolated cDNA for CYP79 provide important tools necessary for tissue-specific regulation of cyanogenic glucoside levels in plants to optimize food safety and pest resistance.     

Polymorphisms of the Cytochrome P450 (CYP1A1, CYP2E1) and Microsomal Epoxide Hydrolase (mEPHX) Genes in Cystic Fibrosis and Chronic Respiratory Disease

Frequencies of CYP1A1, CYP2E1, and mEPHX polymorphic variants were analyzed in cystic fibrosis, chronic obstructive lung disease, bronchiectatic disease, chronic nonobstructive bronchitis, and recurring bronchitis. Mutations in CYP1A1 and mEPHX were shown to modify the severity of respiratory disorders in cystic fibrosis, the combination of CYP1A1 genotype Val/Val with the very slow mEPHX phenotype being most unfavorable (odds ratio OR = 12.30). Heterozygosity at both CYP1A1 and CYP2E1 was associated with chronic obstructive lung disease and recurring bronchitis (OR = 4.08 and 11.72, respectively). The very slow phenotype of mEPHX was predisposing to chronic respiratory disorders regardless of the CYP1A1 or CYP2E1 alleles (OR = 4.06). Basing on the above correlations, a combination of the very slow mEPHX phenotype with elevated cytochrome P450 (CYP1A1 and CYP2E1) activities was assumed to expedite severe respiratory disorders.     

Inflammatory prompts produce isoform-specific changes in the expression of leukotriene B(4) omega-hydroxylases in rat liver and kidney

Cytochrome p450 (CYP) 4Fs metabolize leukotriene B(4) and other inflammatory mediators in the arachidonic acid cascade. Here we show that lipopolysaccharide (LPS) treatment suppresses CYP4F4 and up-regulates CYP4F5 mRNA expression in rat liver whereas renal CYP4Fs are essentially unchanged. BaSO(4) treatment, in contrast, increases both hepatic and renal CYP4F expression levels. Thus, distinct regulatory mechanisms in CYP4F expression might operate under different inflammatory prompts. To examine hepatic totipotency, primary hepatocytes were treated with varying doses of LPS resulting in decrease in all the CYP4F isoforms. Treatment of hepatocytes with 5 ng/ml of interleukin-1beta mimics the in vivo effects of LPS on CYP4F expression.     

The importance of the ratio UV-B/photosynthetic active radiation (PAR) during leaf development as determining factor of plant sensitivity to increased UV-B irradiance: effects on growth, gas exchange and pigmentation of bean plants (Phaseolus vulgaris cv. Label)

To evaluate the effect of different naturally occurring irradiation conditions on the sensitivity of bean (Phaseolus vulgaris cv. Label) to increased UV-B levels, plants were grown under six different light treatments. In the control series (at ambient levels of UV-B), UV-B and visible light were decreased in parallel, resulting in three different total irradiation treatments with the same UV-B/PAR ratio. A second series with a 15% increase in UV-B irradiation at each PAR level was used to investigate the effect of UV-B under the varying total irradiance levels. The different total irradiance levels resulted in large differences in total dry weight, specific leaf weight, photosynthesis-light response and pigment concentrations. Nevertheless, the 15% increase in UV-B resulted in equal reductions in total dry weight (from 24.5 to 34.3%) and effective photosynthesis for all light levels. The accumulation of protective pigments in the primary bean leaves was strongly correlated to the total irradiance level (200% increase from the lowest to the highest light level), but was not influenced by increasing UV-B levels. As the UV-B/PAR ratio outside increases with decreasing total irradiance (when induced by cloud cover) this implies that low radiation levels are potentially dangerous to some plants, even though the UV-B levels may seem negligible.     

Purification of NADPH-P450 reductase (NPR) from Xenopus laevis and the developmental change in NPR expression

NADPH-P450 reductase (NPR) was purified from hepatic microsomes of Xenopus laevis. The electron transfer activity of purified NPR was 23.8 units/min/mg with horse cytochrome c. The aminopyrine demethylation activity of rat CYP2B1 with Xenopus NPR was 58.1 nmol/min/nmol. The corresponding cDNA was isolated from Xenopus liver. The homology in amino acid sequence deduced from NPR cDNA isolated from Xenopus liver was 80%, 78%, and 81% with human, rat, and rabbit NPR, respectively. Antibody against Xenopus NPR was prepared. The expression of NPR was investigated in various tissues and in early development by Western blotting. NPR was most abundantly expressed in the kidney, followed by the liver, lung, and heart. The brain had very low levels of NPR. The level of NPR protein was almost the same at all stages, 2-cell stage (st. 2), blastula (st. 8), gastrula (st. 12), tail bud (st. 26) and larva (st.35), examined in this study. We further investigated the distribution of NPR using whole-mount in situ hybridization. NPR mRNA was expressed in cement gland, lens placode, ear vesicle, mesencephalon, rhombencephalon, lymphatic vessel, and heart anlage in the embryo at stage 29. Xenopus NPR has similar properties to mouse and rat NPRs. Localization of NPR in Xenopus embryo was consistent with the abnormal region caused by NPR deficiency in mice.     

Cloning of rat cytochrome P450RAI (CYP26) cDNA and regulation of its gene expression by all-trans-retinoic acid in vivo

A novel retinoic acid (RA)-inducible cytochrome P450 (P450 RAI or CYP26), previously cloned from human, zebra fish, and mouse, functions in the metabolism of all-trans-RA to polar metabolites including 4-hydroxy-RA and 4-oxo-RA. To further study CYP26 in the rat model, we first cloned rat CYP26 cDNA. The nucleotide sequence predicts a 497-amino-acid protein whose sequence is 95% identical to mouse and 91% homologous to human CYP26. Animal studies showed that CYP26 mRNA expression is very low (0.01+/-0.008;P<0.05) in vitamin-A-deficient rats compared to pair-fed vitamin-A-sufficient rats (defined as 1.0). In a kinetic study, vitamin-A-deficient rats were treated with approximately 100 microg of all-trans-RA and liver was collected after 3-72 h for analysis of CYP26 mRNA by quantitative real-time PCR. Liver CYP26 mRNA increased to nearly 10-fold above control after 3 h (P<0.01), reaching a peak of about 2000-fold greater around 10 h (P<0.001) and then decreased rapidly. The CYP26 dose response to RA was nearly linear (R(2)=0.9638). Additionally, significant regulation of CYP26 gene expression was observed in the vitamin-A-deficient, control, and RA-treated condition in lung, testis, and small intestine. We conclude that CYP26 mRNA expression is dynamically regulated in vivo by diet and RA in hepatic and extrahepatic tissues. The long-term down-regulation of CYP26 in retinoid deficiency may be critical for conserving RA, while the acute up-regulation of CYP26 may be important for preventing a deleterious overshoot of RA derived from either dietary or exogenous sources.     

Cytochrome P450 1 genes in early deuterostomes (tunicates and sea urchins) and vertebrates (chicken and frog): origin and diversification of the CYP1 gene family

Cytochrome P450 family 1 (CYP1) proteins are important in a large number of toxicological processes. CYP1A and CYP1B genes are well known in mammals, but the evolutionary history of the CYP1 family as a whole is obscure; that history may provide insight into endogenous functions of CYP1 enzymes. Here, we identify CYP1-like genes in early deuterostomes (tunicates and echinoderms), and several new CYP1 genes in vertebrates (chicken, Gallus gallus and frog, Xenopus tropicalis). Profile hidden Markov models (HMMs) generated from vertebrate CYP1A and CYP1B protein sequences were used to identify 5 potential CYP1 homologs in the tunicate Ciona intestinalis genome. The C. intestinalis genes were cloned and sequenced, confirming the predicted sequences. Orthologs of 4 of these genes were found in the Ciona savignyi genome. Bayesian phylogenetic analyses group the tunicate genes in the CYP1 family, provisionally in 2 new subfamilies, CYP1E and CYP1F, which fall in the CYP1A and CYP1B/1C clades. Bayesian and maximum likelihood analyses predict functional divergence between the tunicate and vertebrate CYP1s, and regions within CYP substrate recognition sites were found to differ significantly in position-specific substitution rates between tunicates and vertebrates. Subsequently, 10 CYP1-like genes were found in the echinoderm Strongylocentrotus purpuratus (sea urchin) genome. Several of the tunicate and echinoderm CYP1-like genes are expressed during development. Canonical xenobiotic response elements are present in the upstream genomic sequences of most tunicate and sea urchin CYP1s, and both groups are predicted to possess an aryl hydrocarbon receptor (AHR), suggesting possible regulatory linkage of AHR and these CYPs. The CYP1 family has undergone multiple rounds of gene duplication followed by functional divergence, with at least one gene lost in mammals. This study provides new insight into the origin and evolution of CYP1 genes.     

Cloning, Sequencing, and Phylogenetic Analysis of Complementary DNA of Novel Cytochrome P-450 CYP1A in Japanese Eel (Anguilla japonica)

Complementary DNA of cytochrome P-450 CYP1A, in addition to CYP1A1, has been isolated from Japanese eel (Anguilla japonica) liver treated with 3-methylcholanthrene. The cDNA contained a 5′ untranslated region of 66 bp, an open reading frame of 1554 bp coding for 517 amino acids and a stop codon, and a 3′ untranslated region of 1166 bp. The predicted molecular weight of the Japanese eel CYP1A was approximately 58.5 kDa. The nucleotide sequence exhibited identities with the reported CYP1A1 sequences of 77% for Japanese eel, 75% for rainbow trout, 72% for scup, plaice, and butterfly fish, and 71% for toadfish. The deduced amino acid sequence exhibited identities with the reported CYP1A1 sequences of 78% for Japanese eel, 77% for rainbow trout, 75% for scup, 74% for toadfish, 73% for plaice, and 72% for butterfly fish. The novel eel CYP1A obtained had less similarity to the other teleost CYP1A1 proteins (72%–78%) than that of the eel CYP1A1 (74%–80%). When compared with mammalian CYP proteins, the novel eel CYP1A was more similar to the CYP1A1 proteins (54%–56%) than to the CYP1A2 proteins (50%–53%). The phylogenetic tree of the teleost CYP1A genes constructed using the maximum likelihood method suggested that the novel eel CYP1A is ubiquitous among the Anguilliformes. Received August 25, 2000; accepted November 30, 2000