Identification and expression of two novel cytochrome P450 genes, belonging to CYP4 and a new CYP331 family, in the polychaete Capitella capitata sp.I

Exploring the impact of nonylphenol exposure on Litopenaeus vannamei at the histological and molecular levels

Nonylphenol (NP) is one of the common pollutants in the environment that have toxic effects on aquatic animals. Nevertheless, little is known about the possible toxicity mechanism of NP on the hepatopancreas of Litopenaeus vannamei. In the present study, the detrimental effects of NP on the hepatopancreas of the L. vannamei were explored at the histological and transcriptomic levels. The findings indicated that after NP exposed for 3, 12, and 48 h, the hepatopancreas histology was changed significantly. Transcriptomic analysis showed that a total of 4302, 3651, and 4830 differentially expressed genes (DEGs) were identified at 3, 12, and 48 h following NP exposure. All these DEGs were classified into 12 clusters according to the expression patterns at different time points. GO and KEGG enrichment analyses of DEGs were also performed, immunological, metabolic, and inflammatory related pathways, including arachidonic acid metabolism (ko00590), the PPAR signaling pathway (ko03320), and the regulation of TRP channels by inflammatory mediators (ko04750) were significantly enriched. Six DEGs were selected for validation by quantitative real-time PCR (qRT-PCR) and the results confirmed the reliability of transcriptome data. All results indicated that NP is toxic to L. vannamei by damaging the histopathological structure and disrupting the biological function. The findings would provide a theoretical framework for lowering or limiting the detrimental impacts of NP on aquaculture and help us to further study the molecular toxicity of NP in crustaceans.

A broad-taxa approach as an important concept in ecotoxicological studies and pollution monitoring

Aquatic invertebrates play a pivotal role in (eco)toxicological assessments because they offer ethical, cost-effective and repeatable testing options. Additionally, their significance in the food chain and their ability to represent diverse aquatic ecosystems make them valuable subjects for (eco)toxicological studies. To ensure consistency and comparability across studies, international (eco)toxicology guidelines have been used to establish standardised methods and protocols for data collection, analysis and interpretation. However, the current standardised protocols primarily focus on a limited number of aquatic invertebrate species, mainly from Arthropoda, Mollusca and Annelida. These protocols are suitable for basic toxicity screening, effectively assessing the immediate and severe effects of toxic substances on organisms. For more comprehensive and ecologically relevant assessments, particularly those addressing long-term effects and ecosystem-wide impacts, we recommended the use of a broader diversity of species, since the present choice of taxa exacerbates the limited scope of basic ecotoxicological studies. This review provides a comprehensive overview of (eco)toxicological studies, focusing on major aquatic invertebrate taxa and how they are used to assess the impact of chemicals in diverse aquatic environments. The present work supports the use of a broad-taxa approach in basic environmental assessments, as it better represents the natural populations inhabiting various ecosystems. Advances in omics and other biochemical and computational techniques make the broad-taxa approach more feasible, enabling mechanistic studies on non-model organisms. By combining these approaches with in vitro techniques together with the broad-taxa approach, researchers can gain insights into less-explored impacts of pollution, such as changes in population diversity, the development of tolerance and transgenerational inheritance of pollution responses, the impact on organism phenotypic plasticity, biological invasion outcomes, social behaviour changes, metabolome changes, regeneration phenomena, disease susceptibility and tissue pathologies. This review also emphasises the need for harmonised data-reporting standards and minimum annotation checklists to ensure that research results are findable, accessible, interoperable and reusable (FAIR), maximising the use and reusability of data. The ultimate goal is to encourage integrated and holistic problem-focused collaboration between diverse scientific disciplines, international standardisation organisations and decision-making bodies, with a focus on transdisciplinary knowledge co-production for the One-Health approach.

Cryptic Species in Ecotoxicology

The advent of genetic methods has led to the discovery of an increasing number of species that previously could not be distinguished from each other on the basis of morphological characteristics. Even though there has been an exponential growth of publications on cryptic species, such species are rarely considered in ecotoxicology. Thus, the particular question of ecological differentiation and the sensitivity of closely related cryptic species is rarely addressed. Tackling this question, however, is of key importance for evolutionary ecology, conservation biology, and, in particular, regulatory ecotoxicology. At the same time, the use of species with (known or unknown) cryptic diversity might be a reason for the lack of reproducibility of ecotoxicological experiments and implies a false extrapolation of the findings. Our critical review includes a database and literature search through which we investigated how many of the species most frequently used in ecotoxicological assessments show evidence of cryptic diversity. We found a high proportion of reports indicating overlooked species diversity, especially in invertebrates. In terrestrial and aquatic realms, at least 67% and 54% of commonly used species, respectively, were identified as cryptic species complexes. The issue is less prominent in vertebrates, in which we found evidence for cryptic species complexes in 27% of aquatic and 6.7% of terrestrial vertebrates. We further exemplified why different evolutionary histories may significantly determine cryptic species' ecology and sensitivity to pollutants. This in turn may have a major impact on the results of ecotoxicological tests and, consequently, the outcome of environmental risk assessments. Finally, we provide a brief guideline on how to deal practically with cryptic diversity in ecotoxicological studies in general and its implementation in risk assessment procedures in particular. Environ Toxicol Chem 2023;42:1889-1914. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Transcriptomic response to GnRH down regulation by RNA interference in clam Ruditapes philippinarum, suggest possible role in reproductive function

Gonadotropin-releasing hormone (GnRH) plays a key role in the control of the reproductive axis in vertebrates, however, little is known about its function in reproductive endocrine regulation in molluscs. In the present study, RNA-seq was used to construct transcriptomes of Ruditapes philippinarum testis and ovaries of control and GnRH suppressed individuals using RNA interference. GnRH suppression caused 112 and 169 enriched KEGG pathways in testis and ovary, with 92 pathways in common in both comparisons. The most enriched KEGG pathways occurred in the "Oxidative phosphorylation", "Dorso-ventral axis formation", "Thyroid hormone synthesis" and "Oxytocin signaling pathway" etc. A total of 1838 genes in testis and 358 genes in ovaries were detected differentially expressed in GnRH suppressed clams. Among the differentially expressed genes, a suit of genes related to regulation of steroid hormones synthesis and gonadal development, were found in both ovary and testis with RNAi of GnRH. These results suggest that GnRH may play an important role in reproductive function in bivalves. This study provides a preliminary basis for studying the function and regulatory mechanism of GnRH in bivalves.

Identification of a novel CYP4V gene in the polychaete Perinereis aibuhitensis: transcriptional comparison with a CYP4B gene exposed to PAHs

Polychaete worms can biotransform polycyclic aromatic hydrocarbons (PAHs) in environments, and the cytochrome P450 (CYP) enzyme plays an important role in this process. Herein, a novel cytochrome P450 gene was identified and characterized from the polychaete worm Perinereis aibuhitensis. The full-length cDNA, which is named CYP4V82, is 1709 bp encoding a protein of 509 amino acids and has high similarity to CYP4V. The expression levels of CYP4V82 and CYP4BB4 (a CYP gene identified from P. aibuhitensis in a previous study, Chen et al. Mar Pollut Bull 64:1782-1788, 2012) exposure to various concentrations of benzo[a]pyrene (B[a]P) (0.5, 2, 4, and 8 μg/L) and same mass concentrations of fluoranthene (Flu, 3.2 μg/L), phenanthrene (Phe, 2.9 μg/L), B[a]P (4.0 μg/L) were detected to identify the function of the CYP4 family in P. aibuhitensis. Compared with CYP4BB4, CYP4V82 mRNA was minimally expressed on day 7 but highly sensitive on day 14. Notably, the expression levels of CYP4V82 and CYP4BB4 were relatively different in short-term responses to PAHs with different benzene rings of the same concentration. The expression of CYP4V82 in the B[a]P group was the highest, while that of CYP4BB4 in the Phe group was relatively higher than the two other groups. These findings suggest that PAHs are associated with the induction of CYP4V82 and CYP4BB4 expressions in P. aibuhitensis, which may have different efficiencies in the detoxification of PAHs.

Lack of evidence for the role of gut microbiota in PAH biodegradation by the polychaete Capitella teleta

Capitella teleta is a marine sediment-feeding polychaete known to degrade various polycyclic aromatic hydrocarbons (PAHs) and reported to possess genes involved in PAH transformation, such as those in the P450 cytochrome superfamily. Previous research focusing on biodegradation of PAHs by C. teleta demonstrated that these worms are effective biodegraders, but overlooked the possible role of its gut microbiota in facilitating PAH metabolism. Recently, C. teleta's microbiome was characterized and found to contain several bacterial genera known to contain PAH-degrading members, including Acinetobacter, Thalassotalea, and Achromobacter. Despite this, however, no data have thus far been presented demonstrating the role of C. teleta's gut microbiota in PAH degradation. The present study was designed to more conclusively determine the presence of PAH-degrading bacteria in worm digestive tracts and to more clearly distinguish the relative roles of worm versus gut-microbial metabolism in the removal of PAH from sediment. To do this, we manipulated marine sediment microorganisms and worm gut microbiota by autoclaving and antibiotic treatment, respectively. Our results showed that no fluoranthene degradation occurred in microcosms in the absence of worms. More importantly, there was no significant difference in fluoranthene degradation between antibiotic-treated and non-treated worms. We also found no evidence of fluoranthene degradation using resting cells of gut microbes of C. teleta, and we were unable to isolate fluoranthene-degrading bacterial strains from enrichments of polychaete gut contents, despite multiple attempts. Gut microbiota in worms treated with antibiotics recovered, through bidirectional transfer, between worms and sediment after 2 weeks of microcosm incubation, and gut microbes appear to be required for the survival and growth of C. teleta. Our results build on previous studies suggesting that C. teleta itself is primarily responsible for the metabolism of fluoranthene in ingested sediment. We hypothesize that C. teleta's core microbiota, which includes members of Propionibacterium as the most abundant genus, likely aid worms in obtaining key nutrients (e.g., vitamins) from its sediment diet.

Two novel CYP3A isoforms in marine mussel Mytilus coruscus: Identification and response to cadmium and benzo[a]pyrene

CYP3A enzymes play a crucial role in metabolic clearance of a variety of xenobiotics. However, their genetic information and function remain unclear in molluscs. In the present study, two novel CYP3A genes i.e. McCYP3A-1 and McCYP3A-2 were identified and characterized from the thick shell mussel Mytilus coruscus, and their tissue distribution as well as the response to cadmium (Cd) and benzo[a]pyrene (B[α]P) exposure were addressed using real time quantitative RT-PCR (qRT-PCR) and erythromycin N-demethylase (ERND) assay. McCYP3A-1 and McCYP3A-2 possess typically domains of CYP family such as helix-C, helix-I, helix-K, PERF and the heme binding domain as well as the characteristic domains of CYP3s including six SRS motifs. McCYP3A-1 and McCYP3A-2 transcripts were constitutively expressed in all examined tissues with high expression level in digestive glands, hepatopancreas and gonads. Upon B[α]P exposure, McCYP3A-1 and McCYP3A-2 mRNA expression in digestive glands showed a pattern of up-regulation followed by down-regulation, while under Cd exposure, showed a time-dependent induction profile. In addition, ERND activity, generally used as an indicator of CYP3, increased in a time-dependent manner after exposure to Cd and B[α]P. These results collectively indicated that McCYP3A-1 and McCYP3A-2 are CYP3A family member and may play a potential role in metabolic clearance of xenobiotics. Meanwhile, the current results may provide some baseline data to support McCYP3A-1 and McCYP3A-2 as candidate biomarkers for monitoring of PAHs and heavy metal pollution.

Marine copepod cytochrome P450 genes and their applications for molecular ecotoxicological studies in response to oil pollution

Recently, accidental spills of heavy oil have caused adverse effects in marine organisms. Oil pollution can induce damages on development and reproduction, linking with detrimental effects on diverse molecular levels of genes and proteins in plankton and fish. However, most information was mainly focused on marine vertebrates and consequently, limited information was available in marine invertebrates. Furthermore, there is still a lack of knowledge bridging in vivo endpoints with the functional regulation of cytochrome P450 (CYP) genes in response to oil spill pollution in marine invertebrates. In this paper, adverse effects of oil spill pollution in marine invertebrates are summarized with the importance of CYP genes as a potential biomarker, applying for environmental monitoring to detect oil spill using marine copepods.

Evaluation of bioremediation potential of three benthic annelids in organically polluted marine sediment

This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta, and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments.

Transcription of a novel P450 gene varies with some factors (pollutant exposure, temperature, time, and body region) in a marine oligochaete (Thalassodrilides sp.)

Cytochrome P450 (CYP) enzymes play important roles in the metabolism of exogenous compounds such as polycyclic aromatic hydrocarbons (PAHs). A novel, full-length CYP gene (CYP4V30) was identified in the oligochaete Thalassodrilides sp. CYP4V30 mRNA expression was studied in worms exposed to PAH-polluted (Σ16PAHs; 37441ng/g dry weight) or unpolluted (Σ16PAHs; 19ng/g dry weight) sediment. CYP4V30 expression was much higher in worms exposed to contaminated sediments than in those exposed to unpolluted sediments at some temperatures (20 and 25°C) and exposure durations (11-fold increase at 20°C, 10-day exposure), but not at 15°C or other exposure durations (P<0.05). CYP4V30 mRNA expression was higher in the middle of the body than in the posterior (P<0.05). The variation in transcriptional response with exposure time, temperature, and body region indicates that these factors should be considered when monitoring marine sediment pollution.

Differences in the ability of two marine annelid species, Thalassodrilides sp. and Perinereis nuntia, to detoxify 1-nitronaphthalene

Bioremediation is a promising method for remediating environmentally polluted water. We investigated the abilities of two benthic annelid species to biotransform 1-nitronaphthalene, a nitrated polycyclic aromatic hydrocarbon. We used an oligochaete, Thalassodrilides sp. (Naididae), collected from the sediment beneath a fish farm and a polychaete, Perinereis nuntia, which was obtained from a commercial source. Populations of both organisms were exposed to 1400 μg L(-1) of 1-nitronaphthalene in seawater for 3 days in the dark at 20 °C. The concentration of the pollutant decreased to 12 μg L(-1) in the seawater containing the Thalassodrilides sp. and to 560 μg L(-1) in the seawater containing P. nuntia. The 1-nitronaphthalene concentration in the bodies of the animals increased from 12 to 94 μg kg(-1) in Thalassodrilides sp. and from 0.90 μg kg(-1) to 38,000 μg kg(-1) in P. nuntia. After 3 days, 99% and 40% of the 1-nitronaphthalene had been biotransformed in the Thalassodrilides sp. and P. nuntia experimental groups, respectively. We then tested the acute toxicity of residual 1-nitronaphthalene from the same water using mummichog (fish) larvae. After the larvae had been exposed for 96 h, the percentage of apparently unaffected larvae remaining was 83.3% in Thalassodrilides sp. group but only 16.7% in the P. nuntia group. Clearly, of the two species we studied, Thalassodrilides sp. had a superior ability to convert 1-nitronaphthalene into substances that were nontoxic to mummichog larvae. Therefore, we recommend the use of this species for bioremediation of chemically polluted sediments.

Identification of two isoforms of CYP4 in Marsupenaeus japonicus and their mRNA expression profile response to benzo[a]pyrene

CYP4 enzymes are essential components of cellular detoxification systems and play important roles in monitoring persistent organic pollutants in marine environments. However, there are few studies on CYP4 in shrimp. In this study, two CYP4 isoforms, CYP4V28 and CYP4V29, were cloned from Marsupenaeus japonicus for the first time, and the tissue distributions and mRNA expression profile in response to benzo[a]pyrene (B[a]P) were analyzed by quantitative real-time PCR (QRT-PCR). The full lengths of CYP4V28 and CYP4V29 were 1771 bp and 1647 bp respectively, with deduced amino acid sequences of 511 and 515 amino acids. The two CYP4s were predominantly expressed in the hepatopancreas and weakly expressed in other six tested tissues. As demonstrated by QRT-PCR, the mRNA levels of the two CYP4s show both a time- and dose-dependent response to B[a]P. The mRNA expression levels of CYP4V28 and CYP4V29 peaked at 12 h and 6 h respectively, and the peak level exhibited a tendency of positive correlation with the concentration of B[a]P. This study provides clues for further elucidating the function and regulation mechanisms of the two CYP4s in M. japonicas and evaluating of the biomarker potential of the two CYP4 isoforms.

Genetic population structure of polychaeta Neanthes glandicincta (Nereididae) of the Mai Po Inner Deep Bay Ramsar Site, Hong Kong

Neanthes glandicincta (Nereididae, Polychaeta) is the first numerically dominant benthic infauna in the Mai Po international Ramsar site, Hong Kong and also an economically important species for food source of birds and fishes. In present study, highly conserved nuclear ribosomal DNA (SSU and LSU rDNA) and mitochondrial COI gene were employed to study the population structure of N. glandicincta in the subtropical mudflat. The specimens were collected from five localities in February 2006, February-August 2007 and preserved at -80 °C, methanol or formalin, respectively. DNA extraction efficiency was the highest in fresh materials and lowest in formalin-fixed samples. The 18S (1774 bp), 28S D1 (383 bp) and COI genes were sequenced and analyzed. Both 18S and 28S D1 rDNA were highly conserved and showed no difference among the populations, whereas COI gene exhibited relatively high-level intraspecific polymorphism (2.2 %). The population from onshore and near mangrove station was phylogenetic different from other sites, indicating restricted gene exchange between the region of river mouth and mangrove forest. The mangrove may form a barrier for the dispersal of pelagic/benthic larvae of the population, which indicates that the population genetic difference is related to different habitats.

The known and unknown sources of reactive oxygen and nitrogen species in haemocytes of marine bivalve molluscs

Reactive oxygen and nitrogen species (ROS and RNS) are naturally produced in all cells and organisms. Modifications of standard conditions alter reactive species generation and may result in oxidative stress. Because of the degradation of marine ecosystems, massive aquaculture productions, global change and pathogenic infections, oxidative stress is highly prevalent in marine bivalve molluscs. Haemocytes of bivalve molluscs produce ROS and RNS as part of their basal metabolism as well as in response to endogenous and exogenous stimuli. However, sources and pathways of reactive species production are currently poorly deciphered in marine bivalves, potentially leading to misinterpretations. Although sources and pathways of ROS and RNS productions are highly conserved between vertebrates and invertebrates, some uncommon pathways seem to only exist in marine bivalves. To understand the biology and pathobiology of ROS and RNS in haemocytes of marine bivalves, it is necessary to characterise their sources and pathways of production. The aims of the present review are to discuss the currently known and unknown intracellular sources of reactive oxygen and nitrogen species in marine bivalve molluscs, in light of terrestrial vertebrates, and to expose principal pitfalls usually encountered.

The Cytochrome P450 superfamily complement (CYPome) in the annelid Capitella teleta

The Cytochrome P450 super family (CYP) is responsible for a wide range of functions in metazoans, having roles in both exogenous and endogenous substrate metabolism. Annelids are known to metabolize polycyclic aromatic hydrocarbons (PAHs) and produce estrogen. CYPs are postulated to be key enzymes in these processes in annelids. In this study, the CYP complement (CYPome) of the annelid Capitella teleta has been robustly identified and annotated with the genome assembly available. Phylogenetic analyses were performed to understand the evolutionary relationships between CYPs in C. teleta and other species. Predictions of which CYPs are potentially involved in both PAH metabolism and steroidogensis were made based on phylogeny. Annotation of 84 full length and 12 partial CYP sequences predicted a total of 96 functional CYPs in C. teleta. A further 13 CYP fragments were found but these may be pseudogenes. The C. teleta CYPome contained 24 novel CYP families and seven novel CYP subfamilies within existing families. A phylogenetic analysis identified that the C. teleta sequences were found in 9 of the 11 metazoan CYP clans. Two CYPs, CYP3071A1 and CYP3072A1, did not cluster with any metazoan CYP clans. We found xenobiotic response elements (XREs) upstream of C. teleta CYPs related to vertebrate CYP1 (CYP3060A1, CYP3061A1) and from families with reported transcriptional upregulation in response to PAH exposure (CYP4, CYP331). C. teleta had a CYP51A1 with ∼65% identity to vertebrate CYP51A1 sequences and has been predicted to have lanosterol 14 α-demethylase activity. CYP376A1, CYP3068A1, CYP3069A1, and CYP3070A1 were the most appropriate candidates for steroidogenesis genes based on their phylogeny and warrant further analyses, though no specific aromatase (estrogen synthesis) candidates were found. Presence of XREs upstream of C. teleta CYPs may indicate a functional aryl hydrocarbon receptor in C. teleta and candidate CYPs for studies of PAH metabolism.

Crude oil exposure results in oxidative stress-mediated dysfunctional development and reproduction in the copepod Tigriopus japonicus and modulates expression of cytochrome P450 (CYP) genes

In this study, we investigated the effects of the water-accommodated fraction (WAF) of crude oil on the development and reproduction of the intertidal copepod Tigriopus japonicus through life-cycle experiments. Furthermore, we investigated the mechanisms underlying the toxic effects of WAF on this benthic organism by studying expression patterns of cytochrome P450 (CYP) genes. Development of T. japonicus was delayed and molting was interrupted in response to WAF exposure. Hatching rate was also significantly reduced in response to WAF exposure. Activities of antioxidant enzymes such as glutathione S-transferase (GST), glutathione reductase (GR), and catalase (CAT) were increased by WAF exposure in a concentration-dependent manner. These results indicated that WAF exposure resulted in oxidative stress, which in turn was associated with dysfunctional development and reproduction. To evaluate the involvement of cytochrome P450 (CYP) genes, we cloned the entire repertoire of CYP genes in T. japonicus (n=52) and found that the CYP genes belonged to five different clans (i.e., Clans 2, 3, 4, mitochondrial, and 20). We then examined expression patterns of these 52 CYP genes in response to WAF exposure. Three TJ-CYP genes (CYP3024A2, CYP3024A3, and CYP3027C2) belonging to CYP clan 3 were significantly induced by WAF exposure in a time- and concentration-dependent manner. We identified aryl hydrocarbon responsive elements (AhRE), xenobiotic responsive elements (XREs), and metal response elements (MRE) in the promoter regions of these three CYP genes, suggesting that these genes are involved in detoxification of toxicants. Overall, our results indicate that WAF can trigger oxidative stress and thus induce dysfunctional development and reproduction in the copepod T. japonicus. Furthermore, we identified three TJ-CYP genes that represent potential biomarkers of oil pollution.

Identification of a CYP3A-like gene and CYPs mRNA expression modulation following exposure to benzo[a]pyrene in the bivalve mollusk Chlamys farreri

In this study, we isolated a CYP3A-like gene from ovary of the scallop (Chlamys farreri). High levels of CYP3A-like gene expression occur in the digestive gland and gonad, which suggested their role in the metabolism of steroids and xenobiotics. Scallops were exposed to a polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (B[a]P) for 10 days. The CYP4 and CYP3A-like gene can be up-regulated by B[a]P in a dose-dependent manner after 10 days exposure. But no induction of the CYP3A-like was observed in 10 μg/L B[a]P group. The CYP1A-like expression can only be induced by 0.025 μg/L B[a]P. 0.5 and 10 μg/L B[a]P caused significant DNA damage and 10 μg/L B[a]P can also lead to oxidative damage. These results demonstrate that the mollusk CYPs can be modulated by environmental pollutant, and the blocked induction of CYP3A-like and CYP1A-like expression probably results from the high genotoxicity and oxidative damage partly.

Molecular cloning and expression of CYP9A61: a chlorpyrifos-ethyl and lambda-cyhalothrin-inducible cytochrome P450 cDNA from Cydia pomonella

Cytochrome P450 monooxygenases (CYPs or P450s) play paramount roles in detoxification of insecticides in a number of insect pests. However, little is known about the roles of P450s and their responses to insecticide exposure in the codling moth Cydia pomonella (L.), an economically important fruit pest. Here we report the characterization and expression analysis of the first P450 gene, designated as CYP9A61, from this pest. The full-length cDNA sequence of CYP9A61 is 2071 bp long and its open reading frame (ORF) encodes 538 amino acids. Sequence analysis shows that CYP9A61 shares 51%-60% identity with other known CYP9s and contains the highly conserved substrate recognition site SRS1, SRS4 and SRS5. Quantitative real-time PCR showed that CYP9A61 were 67-fold higher in the fifth instar larvae than in the first instar, and more abundant in the silk gland and fat body than other tissues. Exposure of the 3rd instar larvae to 12.5 mg L(-1) of chlorpyrifos-ethyl for 60 h and 0.19 mg L(-1) of lambda-cyhalothrin for 36 h resulted in 2.20- and 3.47-fold induction of CYP9A61, respectively. Exposure of the 3rd instar larvae to these two insecticides also significantly enhanced the total P450 activity. The results suggested that CYP9A61 is an insecticide-detoxifying P450.

Expression pattern of entire cytochrome P450 genes and response of defensomes in the benzo[a]pyrene-exposed monogonont rotifer Brachionus koreanus

Cytochrome P450 (CYP) proteins are involved in the first line of detoxification mechanism against diverse polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P). In aquatic invertebrates, there is still a lack of knowledge on the CYP genes involved in the molecular response to B[a]P exposure due to limited gene information. In this study, we cloned the entire 25 CYP genes in the monogonont rotifer Brachionus koreanus with the aid of next generation sequencing (NGS) technologies and analyzed their transcript profiles with a real-time RT-PCR array to better understand B[a]P-triggered molecular response over different time courses. As a result, B[a]P exposure induced CYP2/3-involved detoxification mechanisms and defensome, including phase II detoxification and antioxidant systems with a modulation of the chaperone heat shock protein (hsp) expression but did not change expression of other CYP clans in B. koreanus . Therefore, we found that B[a]P induced a strong detoxification mechanism to overcome detrimental effects of B[a]P associated with B[a]P-induced growth retardation as a trade-off in fitness costs. Also, this approach revealed that the entire CYP profiling can be a way of providing a better understanding on the mode of action of B[a]P in B. koreanus with respect to molecular defense metabolism.

Expression of three novel cytochrome P450 (CYP) and antioxidative genes from the polychaete, Perinereis nuntia exposed to water accommodated fraction (WAF) of Iranian crude oil and benzo[a]pyrene

To report a novel CYP genes and to evaluate its potency as a biomarker for oil pollution, we cloned three CYP genes and measured their expression profiles under controlled lab conditions using real-time reverse transcription PCR (real-time RT-PCR) after exposure of the water accommodated fraction (WAF) of Iranian crude oil and benzo[α]pyrene (B[α]P) as a positive control. Of these, CYP432A1 (CYP3 clan) gene was significantly induced by B[α]P exposure, indicating that the CYP3 clan gene would play an important role in polycyclic aromatic hydrocarbon (PAH) metabolisms, particularly for B[α]P in this species. However, the Perinereis nuntia CYP431A1 mRNA, a CYP2 clan gene, was sensitively expressed to WAF exposure with other two CYP genes. As one of Phase II detoxification enzymes, the glutathione S-transferase (GST) genes also upregulated with other antioxidant genes (SOD and CAT), indicating that WAF-exposed P. nuntia was properly responding to this kind of chemical stress. Thus, three CYP genes from the polychaete, P. nuntia have a potential as a biomarker in monitoring of the marine sediment after an oil spill accident.

Three novel cytochrome P450 genes identified in the marine polychaete Perinereis nuntia and their transcriptional response to xenobiotics

Polychaetes have previously been used as bioindicators of environmental pollution. Their ability to eliminate organic pollutants such as polycyclic aromatic hydrocarbons (PAH) has been extensively analyzed. However, the cytochrome P450 monooxygenases (CYP) genes in polychaetes, which catalyze the first step of oxidative degradation of PAHs, have received little attention. Based on the partial sequences of three CYP genes that were enriched by subtractive cDNA libraries of the polychaete Perinereis nuntia, we amplified and sequenced the full-length cDNA of these novel CYP genes. These genes were named CYP4BB2, CYP423A1 and CYP424A1 by the Cytochrome P450 Nomenclature Committee. The deduced amino acid sequence of CYP4BB2 in P. nuntia showed 68% sequence identity to CYP4BB1 in Nereis virens, and was listed as a new member of the CYP4BB subfamily. The sequence of CYP423A1 and CYP424A1 both share less than 40% sequence identity to all known CYP enzymes and were classed into new CYP families. CYP family members are composite parts of a larger group called a clan. CYP4BB2 and CYP424A1 are listed as CYP4 clan members, while CYP423A1 is of the CYP2 clan. The 3D structures of these P. nuntia CYPs were successfully predicted by homology-modeling using the SWISS-MODEL workspace. The models of CYP424A1 and CYP4BB2 were created using 1jpzB (CYP102A) as a template, while CYP423A1 utilized 3czhB (CYP2R1) as its template. The presence of characteristic CYP superfamily motifs, such as the F-G⋯C-G amino acid sequence, and the conservation of the three-dimensional CYP structure shown by the modeling, suggested that these novel P. nuntia CYP genes may contain conserved functional domains of CYP monooxygenases. To examine the effect of xenobiotics on living organisms, we analyzed the transcriptional levels of these three new CYP genes in sandworms (P. nuntia) exposed to seawater artificially contaminated with benzo[a]pyrene (BaP). We also exposed individuals to industrial wastewater collected from Quanzhou Bay, Fujian, China, which was known to be contaminated with PAHs. Worms exposed to BaP had significantly higher levels of CYP4BB2, CYP423A1 and CYP424A1 mRNA. Transcription was up-regulated 5.9-, 5.3- and 12.3-folds respectively compared with the control worms living in clean seawater. The transcriptional levels of CYPs in worms cultured in the diluted wastewater collected from Quanzhou Bay, all positively correlated with the levels of PAHs detected in the water. The transcriptional up-regulation of the three CYP genes observed in this study, suggest the monooxygenases encoded by these CYP genes may play an important role in the detoxification of PAHs in this polychaete worm. These CYPs maybe essential for the adaptation of worms to contaminated environments and may be useful in the assessment of xenobiotic exposure.

CYP4 mRNA expression in marine polychaete Perinereis aibuhitensis in response to petroleum hydrocarbon and deltamethrin

A CYP4 cDNA was cloned and characterized to identify the relationship between persistent organic pollutants and stress response in marine polychaete Perinereis aibuhitensis. The full length of PaCYP4 cDNA is 1857bp and encodes 481 amino acids. The deduced amino acid sequence showed 73% identity with CYP4BB1 from polychaete Nereis virens and shared high homology to other known CYP4 sequences. The expression level of PaCYP4 under petroleum hydrocarbon (PH) and deltamethrin (DM) exposure was detected using Real-time PCR. PH and combined toxicity treatments elevated the mRNA level of PaCYP4 in a dose- and time-dependent manner. The mRNA transcripts of PaCYP4 increased at the beginning of DM exposure and then eventually decreased, and the expression level of PaCYP4 down-regulated with increasing concentration of DM. CYP4 in P. aibuhitensis plays an important role in the metabolism of petroleum hydrocarbon and organochlorine pesticide.

The polychaete, Perinereis nuntia ESTs and its use to uncover potential biomarker genes for molecular ecotoxicological studies

The polychaete, Perinereis nuntia, has been used as an indicator species to assess the environmental condition of benthic communities in coastal marine environments. Recently, high-throughput sequencing technology has been proven to be a useful method for analyzing expressed sequence tags (ESTs) in non-model species. Thus, we have obtained extensive cDNA information by the pyrosequencing method, to utilize the polychaete species as a test organism for sediment quality monitoring studies. From the total RNA of P. nuntia, cDNA was reversely synthesized and randomly sequenced using a GS-FLX sequencer. In the assembly stage 1, 40,379 transcripts (13,666 contigs and 26,713 singletons) were acquired and showed 47% hitting rate compared with the GenBank non-redundant (NR) amino acid sequence database using BLASTX. After the stage-2 assembly, 21,657 transcripts were identified and showed 28% hitting rate. Finally, we obtained 6 064 unigenes that corresponded to the GenBank NR amino acid sequence database using BLASTX. Of the transcripts obtained in this species, we found a number of stress- and cell defense-related genes (e.g. heat shock protein family, antioxidant-related genes, cytochrome P450 genes) that are potentially useful for sediment monitoring at the molecular level, indicating that the pyrosequencing method is an effective approach to uncover gene families of potential biomarker genes simultaneously, and thus make transcriptomic studies possible. To confirm the usefulness of those potential biomarker genes, we analyzed the comparative profiling of P. nuntia mRNA transcripts between the samples collected from the polychaete aquaculture farm and the southern coast field of South Korea. In this paper, we summarize the expressed cDNA information of P. nuntia and discussed its potential use in environmental genomics and ecotoxicological studies for uncovering the potential molecular mechanisms of environmental stresses and chemical toxicity to the indicator species, P. nuntia in marine sediments.

Identification of a novel P450 gene belonging to the CYP4 family in the clam Ruditapes philippinarum, and analysis of basal- and benzo(a)pyrene-induced mRNA expression levels in selected tissues

A novel full-length cDNA encoding a CYP4 protein was initially cloned from the clam, Ruditapes philippinarum. The nucleotide sequence contained an open reading frame coding for 442 amino acids and the deduced amino acid sequence showed 42.6-49.1% identity with other species CYP4s. The phylogenetic analysis demonstrated that the clam CYP4 was clustered within the CYP4s branch. The clam CYP4 mRNA expression was detected in gill, digestive gland, adductor muscle and mantle, and highest transcription level was observed in digestive gland compared to other tissues. Quantitative real-time RT-PCR analysis revealed that there was no notable change in CYP4 mRNA expression in gill of R. philippinarum exposure to benzo(a)pyrene (BaP), while the mRNA expression was induced significantly in the digestive gland of the clam by 0.2 ppb (μgL(-1)) BaP (p<0.05). The results suggest that CYP4 of the clam may serve as a useful biomarker of marine environmental PAH pollution.

Differential expression of proteins and phosphoproteins during larval metamorphosis of the polychaete Capitella sp. I

BACKGROUND

The spontaneous metamorphosis of the polychaete Capitella sp. I larvae into juveniles requires minor morphological changes, including segment formation, body elongation, and loss of cilia. In this study, we investigated changes in the expression patterns of both proteins and phosphoproteins during the transition from larvae to juveniles in this species. We used two-dimensional gel electrophoresis (2-DE) followed by multiplex fluorescent staining and MALDI-TOF mass spectrometry analysis to identify the differentially expressed proteins as well as the protein and phosphoprotein profiles of both competent larvae and juveniles.

RESULTS

Twenty-three differentially expressed proteins were identified in the two developmental stages. Expression patterns of two of those proteins were examined at the protein level by Western blot analysis while seven were further studied at the mRNA level by real-time PCR. Results showed that proteins related to cell division, cell migration, energy storage and oxidative stress were plentifully expressed in the competent larvae; in contrast, proteins involved in oxidative metabolism and transcriptional regulation were abundantly expressed in the juveniles.

CONCLUSION

It is likely that these differentially expressed proteins are involved in regulating the larval metamorphosis process and can be used as protein markers for studying molecular mechanisms associated with larval metamorphosis in polychaetes.

Two novel cytochrome P450 genes CYP6CS1 and CYP6CW1 from Nilaparvata lugens (Hemiptera: Delphacidae): cDNA cloning and induction by host resistant rice

Two novel full-length P450 cDNAs, CYP6CS1 and CYP6CW1, were cloned from the fourth instar nymphs of brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae) reared on its susceptible rice variety Taichung Native 1 (TN1) plants. The deduced proteins are typical microsomal P450s sharing conserved structural and functional domains with other insect CYP6 members. Temporal expression analysis by northern blot hybridization indicated pre-exposure to N. lugens moderately resistant rice Minghui 63 (MH63) seedlings caused a time course-dependent induction of CYP6CS1 which peaked after 24 h of treatment; in contrast, CYP6CW1 was induced and remained at a constant time course from 0-72 h. CYP6CS1 and CYP6CW1 are dramatically induced in gut tissues and, slightly upregulated in carcass and fat bodies as revealed in spatial gene expression analysis. Whole mount in situ hybridizaion revealed that the two genes are expressed at a basal level in gut tissue and Malpighian tubules in nymphs fed with TN1 rice. After exposure to MH63, the expression of CYP6CW1 was found to be high in the whole gut, including Malpighian tubules. Expression of CYP6CS1 was significantly increased in midgut, and slightly increased in foregut, hindgut and Malpighian tubules. These data suggest a potential role of the two P450s in determining patterns of N. lugens-rice relationships through allelochemical detoxification.

Biotransformation of polycyclic aromatic hydrocarbons in marine polychaetes

Deposit-feeding polychaetes constitute the dominant macrofauna in marine environments that tend to be depositional centers for organic matter and contaminants. Polychaetes are known to accumulate polycyclic aromatic hydrocarbons (PAHs) from both particulate and dissolved phases but less is known about the mechanisms underlying elimination of accumulated PAHs. An important pathway of elimination is through biotransformation which results in increased aqueous solubility of the otherwise hydrophobic PAHs. Biotransformation in marine polychaetes proceeds in a two phased process similar to those well studied in vertebrates, phase I enzymes belonging to the Cytochrome P450 (CYP) enzyme family, along with a few phase II enzymes have been identified in marine polychaetes. In this review we aim at highlighting advances in the mechanistic understanding of PAH biotransformation in marine polychaetes by including data obtained using analytical chemistry and molecular techniques. In marine polychaetes induction of CYP enzyme activity after exposure to PAHs and the mechanism behind this is currently not well established. Conflicting results regarding the inducibility of CYP enzymes from polychaetes have led to the suggestion that induction in polychaetes is mediated through a different mechanistic pathway, which is corroborated by the apparent lack of an AhR homologous in marine polychaetes. Also, none of the currently identified CYP genes from marine polychaetes are isoforms of those regulated by the AhR in vertebrates. Relatively few studies of phase II enzymes in marine polychaetes are currently available and most of these studies have not measured the activity of specific phase II enzymes and identified phase II metabolites but used an extraction technique only allowing determination of the overall amount of phase II metabolites. Studies in insects and various marine invertebrates suggest that in invertebrates, enzymes in the important phase II enzyme family, UDP-glucuronosyl transferases primarily use glucoside as co-substrate as opposed to the vertebrate cosubstrate glucuronic acid. Recent studies in marine polychaetes have however identified glucuronidation of PAHs indicating no mechanistic difference in co-substrate preference among UDP-glucuronosyl transferases between vertebrates and marine polychaetes but it might suggest a mechanistic difference between marine polychaetes and insects.

Marine invertebrate cytochrome P450: emerging insights from vertebrate and insects analogies

Cytochrome P450 enzymes (P450s) are responsible for the oxidative metabolism of a plethora of endogenous and exogenous substrates. P450s and associated activities have been demonstrated in numerous marine invertebrates belonging to the phyla Cnidaria, Annelida (Polychaeta), Mollusca, Arthropoda (Crustacea) and Echinodermata. P450s of marine invertebrates and vertebrates show considerable sequence divergence and the few orthologs reveal the selective constraint on physiologically significant enzymes. P450s are present in virtually all tissues of marine invertebrates, although high levels usually are found in hepatic-like organs and steroidogenic tissues. High-throughput technologies result in the rapid acquisition of new marine invertebrate P450 sequences; however, the understanding of their function is poor. Based on analogy to vertebrates and insects, it is likely that P450s play a pivotal role in the physiology of marine invertebrates by catalyzing the biosynthesis of signal molecules including steroids such as 20-hydroxyecdysone (the molting hormone of crustaceans). The metabolism of many exogenous compounds including benzo(a)pyrene (BaP), pyrene, ethoxyresorufin, ethoxycoumarin and aniline is mediated by P450 enzymes in tissues of marine invertebrates. P450 gene expression, protein levels and P450 mediated metabolism of xenobiotics are induced by PAHs in some marine invertebrate species. Thus, regulation of P450 enzyme activity may play a central role in the adaptation of animals to environmental pollutants. Emphasis should be put on the elucidation of the function and regulation of the ever-increasing number of marine invertebrate P450s.

Characterisation of two novel CYP4 genes from the marine polychaete Nereis virens and their involvement in pyrene hydroxylase activity

Cytochrome P450 enzymes (CYP enzymes) catalyse the initial step in biotransformation of xenobiotics like polycyclic aromatic hydrocarbons (PAHs). The marine polychaete Nereis virens has a high capacity for biotransformation of PAHs. In the present study, the complete cDNA sequences of two novel CYP genes isolated from N. virens gut tissue are reported. One named CYP342A1, the first member of a new family and the other named CYP4BB1, the first member of a new subfamily. This is the first investigation of specific CYP enzymes from marine polychaetes in which catalytic activity has been determined. Both CYP enzymes had monooxygenase activity and catalysed hydroxylation of pyrene to 1-hydroxypyrene. Based on the present results it is likely that both CYP4BB1 and CYP342A1 are involved in xenobiotic biotransformation. Furthermore, site-directed mutagenesis of the conserved cysteine residue of the heme binding domain resulted in complete loss of monooxygenase activity of both CYP enzymes, indicating that this cysteine residue is indispensable for monooxygenase activity of invertebrate CYP enzymes, as has been well documented in vertebrates. Considering the important role of CYP enzymes in biotransformation of xenobiotics and the presence of N. virens in estuarine environments that accumulates organic xenobiotics, our results are important in understanding the molecular mechanism of biotransformation in marine polychaetes.

Differences in PAH tolerance between Capitella species: underlying biochemical mechanisms

The polychaete Capitella capitata consists of a species complex within which differences in tolerance to toxicants have been observed. For example, it has been shown that Capitella sp. S is more sensitive (e.g., in terms of survival, growth and reproduction) to PAH and other stressors than the more opportunistic Capitella sp. I, which is able to take up and biotransform the PAH fluoranthene (Flu). In the present study, an investigation was performed to examine whether differences in tolerance between Capitella species sp. I and sp. S are due to differences in biotransformation, measured as the amount of Flu-metabolites produced by worms. We exposed both sibling species to sediment contaminated with 21 and 26 microg Flu/g dry weight sed for 10--15 days. We found that Capitella sp. I took up more Flu from the sediment than sp. S (346 microg Flu eq./g dry weight worm versus 219 microg Flu eq./g dry weight worm, respectively), but as sp. I was much more effective at biotransforming this PAH (62% versus 11%, respectively of total Flu), the net amounts of parent Flu accumulated by the two species were similar. We found significant differences in the subcellular distribution of Flu and its metabolites between sibling species, with sp. I accumulating mostly in the cytosol and sp. S accumulating mostly in the membrane fraction. A previous study by our group showed Flu to be genotoxic to sp. I upon biotransformation. In the present study, we found no detectable genotoxicity in sp. S following Flu exposure. Our results demonstrate that DNA damage is tightly coupled to biotransformation ability and that other aspects of PAH toxicity (e.g., membrane disruption) are more relevant than DNA damage for predicting tolerance differences between these species.