Comparative absorption and tissue distribution of 14C-benzo(a)pyrene and 14C-phenanthrene in the polar cod (Boreogadus saida) following oral administration

Published version. Source at http://doi.org/10.1007/s00300-015-1816-7.The Arctic is an important sink for organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) long-range transported from industrial regions. With the retreat of sea ice and increasing anthropogenic activities such as the oil and gas industries, local sources of PAHs are expected to increase both through operational and accidental discharges. There is a need to increase our knowledge concerning the uptake and distribution of organic pollutants, in particular PAHs, to evaluate the risk these toxic compounds may represent for Arctic species. The absorption and tissue distribution of 14C-benzo(a)pyrene (BaP) and 14C-phenanthrene (Phen) were studied in the polar cod (Boreogadus saida), a key Arctic species. After a single oral dose of BaP (1.15 ± 0.36 mg/kg fish) or Phen (0.40 ± 0.12 mg/kg fish), corresponding to 0.12 ± 0.03 mCi/kg fish, the tissue distribution was followed through 30 days by means of whole-body autoradiography and liquid scintillation counting of liver and bile. For both compounds, radiolabeling was mainly present in the bile and the intestines throughout the study period. Phen-derived radioactivity, however, appeared to be more systemically distributed compared to BaP. Furthermore, a far higher amount of irreversibly bound BaP-derived radioactivity was present in the intestinal mucosa compared to Phen, indicating a more extensive formation of reactive intermediates from the former compared with the latter. Liquid scintillation counting confirmed that radioactivity was present in the liver at all time points for both groups although the levels were low in the BaP group. These results strongly indicated that both compounds and/or their metabolites undergo enterohepatic circulation

Deltamethrin resistance in the salmon louse, Lepeophtheirus salmonis (Krøyer): Maternal inheritance and reduced apoptosis

publishedVersio

Candidate genes for monitoring hydrogen peroxide resistance in the salmon louse, Lepeophtheirus salmonis

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Candidate genes for monitoring hydrogen peroxide resistance in the salmon louse, Lepeophtheirus salmonis

publishedVersio

Aménagement conventionnel de la liberté de résiliation : l'exclusion d'un préavis et de toute indemnité est-il possible ? Note sous Cour de cassation, première Chambre civile, 17 février 2011, pourvoi numéro 10-13.980

National audienceno abstrac

Création de tomates résistantes aux Liriomyza dans les différentes écologies tropicales

<div><p>Acetylcholinesterase (AChE) is an important enzyme in cholinergic synapses. Most arthropods have two genes (<i>ace1</i> and <i>ace2</i>), but only one encodes the predominant synaptic AChE, the main target for organophosphates. Resistance towards organophosphates is widespread in the marine arthropod <i>Lepeophtheirus salmonis</i>. To understand this trait, it is essential to characterize the gene(s) coding for AChE(s). The full length cDNA sequences encoding two AChEs in <i>L</i>. <i>salmonis</i> were molecularly characterized in this study. The two ace genes were highly similar (83.5% similarity at protein level). Alignment to the <i>L</i>. <i>salmonis</i> genome revealed that both genes were located close to each other (separated by just 26.4 kbp on the <i>L</i>. <i>salmonis</i> genome), resulting from a recent gene duplication. Both proteins had all the typical features of functional AChE and clustered together with AChE-type 1 proteins in other species, an observation that has not been described in other arthropods. We therefore concluded the presence of two versions of <i>ace1</i> gene in <i>L</i>. <i>salmonis</i>, named <i>ace1a</i> and <i>ace1b</i>. <i>Ace1a</i> was predominantly expressed in different developmental stages compared to <i>ace1b</i> and was possibly active in the cephalothorax, indicating that <i>ace1a</i> is more likely to play the major role in cholinergic synaptic transmission. The study is essential to understand the role of AChEs in resistance against organophosphates in <i>L</i>. <i>salmonis</i>.</p></div

Fold difference in transcription between developmental stages.

<p>This figure displays the relative transcript levels of <i>ace1a</i> and <i>ace1b</i> at 7 different developmental stages of <i>Lepeophtheirus salmonis</i>. The relative expression level of <i>ace1a</i> was significantly higher than <i>ace1b</i>, especially at the copepodid (26 fold) stage and in preadult females (13 fold). The error bars indicate the SD (n = 3) and the experiment was performed in triplicates.</p

Genomic organization.

<p><i>L</i>. <i>salmonis</i> assembly (sealouse.imr.no) was used to find the organization of the LS-ace1-A and <i>ace1b</i> LS-ace1-B in the <i>L</i>. <i>salmonis</i> genome. <i>Ace1a</i> is larger in size (48 kbp) with 8 exons compared to <i>ace1b</i> (3 kbp) with only 5 exons. The size of the exons (dark boxes) and intron (lines) are not at scale. The two genes were separated from each other by <i>a</i> genomic distance of 26.4 kbp and are encoded in opposite direction.</p

Alignment of Ls AChE1a and Ls AChE1b proteins with other AChE from other species.

<p>Alignment of AChE1a and AChE1b proteins from <i>Lepeophtheirus salmonis</i> (abbreviated to LS_ace1-A and LS_ace1-B) with AChE proteins from other species: <i>Cimex lectularius</i> AChE1; JN563927.1 (Cim__lec_ace1), and <i>Torpedo californica</i> AChE; CAA27169.1 (Tor_cal). By convention, numbering is that of <i>T</i>. <i>californica</i>. The three amino acids composing the catalytic triad (S200, E327 and H440) are indicated by arrows. The 14 conserved aromatic residues lining the active gorge are represented by circles. Out of these 14, 11 residues were present in both <i>L</i>. <i>salmonis</i> AChE1a and AChE1b (shown by filled circles), whereas the other 3 non conserved residues (shown by open circles) were absent in both the proteins of salmon louse. The choline binding site (W at 84) is underlined. Three interchain disulphide bridges are drawn between conserved C residues (shown by arrows). The solid box represents the canonical *FGESAG* motif, characteristic of the active site of cholinesterases. The dotted box represents the typical sequence insertion/deletion domain that easily distinguishes AChE1 and AChE2 proteins.</p