Toxicity evaluation of benzo[a]pyrene on the polychaete Perinereis nuntia using subtractive cDNA libraries

Diverse Localization Patterns of an R-Type Lectin in Marine Annelids

Lectins facilitate cell–cell contact and are critical in many cellular processes. Studying lectins may help us understand the mechanisms underlying tissue regeneration. We investigated the localization of an R-type lectin in a marine annelid (Perinereis sp.) with remarkable tissue regeneration abilities. Perinereis nuntia lectin (PnL), a galactose-binding lectin with repeating Gln-X-Trp motifs, is derived from the ricin B-chain. An antiserum was raised against PnL to specifically detect a 32-kDa lectin in the crude extracts from homogenized lugworms. The antiserum detected PnL in the epidermis, setae, oblique muscle, acicula, nerve cord, and nephridium of the annelid. Some of these tissues and organs also produced Galactose (Gal) or N-acetylgalactosamine (GalNAc), which was detected by fluorescent-labeled plant lectin. These results indicated that the PnL was produced in the tissues originating from the endoderm, mesoderm, and ectoderm. Besides, the localizing pattern of PnL partially merged with the binding pattern of a fluorescent-labeled mushroom lectin that binds to Gal and GalNAc. It suggested that PnL co-localized with galactose-containing glycans in Annelid tissue; this might be the reason PnL needed to be extracted with haptenic sugar, such as d-galactose, in the buffer. Furthermore, we found that a fluorescein isothiocyanate-labeled Gal/GalNAc-binding mushroom lectin binding pattern in the annelid tissue overlapped with the localizing pattern of PnL. These findings suggest that lectin functions by interacting with Gal-containing glycoconjugates in the tissues.

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.

Exposure to low pH induces molecular level changes in the marine worm, Platynereis dumerilii

Fossil fuel emissions and changes in net land use lead to an increase in atmospheric CO2 concentration and a subsequent decrease of ocean pH. Noticeable effects on organisms' calcification rate, shell structure and energy metabolism have been reported in the literature. To date, little is known about the molecular mechanisms altered under low pH exposure, especially in non-calcifying organisms. We used a suppression subtractive hybridisation (SSH) approach to characterise differentially expressed genes isolated from Platynereis dumerilii, a non-calcifying marine polychaeta species, kept at normal and low pH conditions. Several gene sequences have been identified as differentially regulated. These are involved in processes previously considered as indicators of environment change, such as energy metabolism (NADH dehydrogenase, 2-oxoglutarate dehydrogenase, cytochrome c oxidase and ATP synthase subunit F), while others are involved in cytoskeleton function (paramyosin and calponin) and immune defence (fucolectin-1 and paneth cell-specific alpha-defensin) processes. This is the first study of differential gene expression in a non-calcifying, marine polychaete exposed to low pH seawater conditions and suggests that mechanisms of impact may include additional pathways not previously identified as impacted by low pH in other species.

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.

Effects of low seawater pH on the marine polychaete Platynereis dumerilii

An important priority for any organism is to maintain internal cellular homeostasis including acid-base balance. Yet, the molecular level impacts of changing environmental conditions, such as low pH, remain uncharacterised. Herein, we isolate partial Na(+)/H(+)exchangers (NHE), carbonic anhydrase (CA), and calmodulin (CaM) genes from a polychaete, Platynereis dumerilii and investigate their relative expression in acidified seawater conditions. mRNA expression of NHE was significantly down-regulated after 1h and up-regulated after 7days under low pH treatment (pH 7.8), indicating changes in acid-base transport. Furthermore, the localisation of NHE expression was also altered. A trend of down regulation in CA after 1h was also observed, suggesting a shift in the CO2 and HCO3(-) balance. No change in CaM expression was detected after 7days exposure to acidified seawater. This study provides insight into the molecular level changes taking place following exposure to acidified seawater in a non-calcifying, ubiquitous, organism.

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.

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.

Susceptibility to oxidative stress and modulated expression of antioxidant genes in the copper-exposed polychaete Perinereis nuntia

To identify and evaluate potentially useful biomarkers for oxidative stress as early warning indices in the polychaete, Perinereis nuntia, we exposed P. nuntia to copper (Cu) and measured several biomarker enzymes (glutathione S-transferase; GST, glutathione peroxidase; GPx, Metallothionein-like protein; MTLPs, and catalase; CAT) and genes (Pn-GSTs, Pn-CAT, and Pn-MT) with a cellular oxidative index, reactive oxygen species (ROS) level. Accumulated Cu concentrations in P. nuntia increased in a time-dependent manner. Intracellular ROS reached high levels 6h after exposure in P. nuntia with an increase of GST activity and glutathione (GSH) content. Particularly, GSH in polychaetes showed a positive correlation with Cu contents accumulated in P. nuntia. Messenger RNA expressions of GST sigma and GST omega showed relatively high expressions at 50 μg/L of Cu exposure, even though the moderate increase of rest of GST isoforms was also observed. Also regarding long-term exposure, we reared P. nuntia in sediments for 15 days, and found that there was an obvious increase of Pn-GSTs, Pn-CAT, and Pn-MT genes with elevated concentrations of Cu and Cd in polychaete body, compared to initial levels, suggesting that P. nuntia in sediment was affected by metals as well as by other organic pollutants to induce oxidative stress genes and enzymes. These findings suggest that oxidative stress is a potential modulator of defense system of P. nuntia. Several potential biomarker genes are available as early warning signals for environmental biomonitoring.