Differential bioaccumulation behaviour of Ag and Cd during the early development of the cuttlefish Sepia officinalis

Effect of polycyclic aromatic hydrocarbons on homeobox gene expression during embryonic development of cuttlefish, Sepia officinalis

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) commonly found in marine environments. Their bioaccumulation can cause harm to aquatic organisms, including invertebrates, particularly during the early stages of embryonic development. In this study, we evaluated, for the first time, the patterns of PAH accumulation in both capsule and embryo of common cuttlefish (Sepia officinalis). In addition, we explored the effects of PAHs by analysing the expression profiles of seven homeobox genes [i.e., gastrulation brain homeobox (GBX), paralogy group labial/Hox1 (HOX1), paralogy group Hox3 (HOX3), dorsal root ganglia homeobox (DRGX), visual system homeobox (VSX), aristaless-like homeobox (ARX) and LIM-homeodomain transcription factor (LHX3/4)]. We found that PAH levels in egg capsules were higher than those observed in chorion membranes (35.1 ± 13.3 ng/g vs 16.4 ± 5.9 ng/g). Furthermore, PAHs were also found in perivitellin fluid (11.5 ± 5.0 ng/ml). Naphthalene and acenaphthene were the congeners present at highest concentrations in each analysed egg component suggesting higher bioaccumulation rates. Embryos with high concentrations of PAHs also showed a significant increase in mRNA expression for each of the analysed homeobox genes. In particular, we observed a 15-fold increase in the ARX expression levels. Additionally, the statistically significant variation in homeobox gene expression patterns was accompanied by a concomitant increase in mRNA levels of both aryl hydrocarbon receptor (AhR) and estrogen receptor (ER). These findings suggest that bioaccumulation of PAHs may modulate developmental processes of cuttlefish embryos by targeting homeobox gene-mediated transcriptional outcomes. Mechanisms underlying the upregulation of homeobox genes could be related to the ability of PAHs to directly activate AhR- or ER-related signaling pathways.

Embryonic exposure to environmentally relevant levels of tributyltin affects embryonic tributyltin bioaccumulation and the physiological responses of juveniles in cuttlefish (Sepia pharaonis)

Tributyltin (TBT) is a typical organic pollutant that persists in aquatic sediments due to its wide usage as an antifouling fungicide during the past few decades. Despite increased awareness of the serious negative consequences of TBT on aquatic species, studies on the effects of TBT exposure on cephalopod embryonic development and juvenile physiological performance are scarce. To investigate the lasting effects of TBT toxicity on Sepia pharaonis from embryo to hatchling, embryos (gastrula stage, 3-5 h post fertilization) were exposed to four levels of TBT until hatching: 0 (control), 30 (environmental level), 60, and 120 ng/L. Subsequently, juvenile growth performance endpoints and behavioral alterations were assessed over 15 days post-hatching. Egg hatchability was significantly reduced and embryonic development (i.e., premature hatching) was accelerated in response to 30 ng/L TBT exposure. Meanwhile, TBT-induced alterations in embryonic morphology primarily included yolk-sac lysis, embryonic malformations, and uneven pigment distributions. During the pre-middle stage of embryonic development, the eggshell serves as an effective barrier to safeguard the embryo from exposure to 30-60 ng/L TBT, according to patterns of TBT accumulation and distribution in the egg compartment. However, even environmental relevant levels of TBT (30 ng/L) exposure during embryonic development had a negative impact on juvenile behavior and growth, including slowing growth, shortening eating times, causing more irregular movements, and increasing inking times. These findings indicate that after TBT exposure, negative long-lasting effects on S. pharaonis development from embryo to hatchling persist, suggesting that long-lasting toxic effects endure from S. pharaonis embryos to hatchlings.

Delineation of metals and radionuclides bioconcentration in eggs of seabream Sparus aurata and effect of environmental pCO2

Considered as the most vulnerable ontogenic stages to environmental stressors, the early-life stages of fish paid a peculiar attention with respect to their vulnerability to metal and radionuclides contamination. Concomitantly, the increasing anthropogenic CO₂ release in the atmosphere will cause major change of the seawater chemistry that could affect the trace elements and radionuclides bioconcentration efficiencies by marine organisms. The aim of this work was to 1) delineate the uptake behaviours of Ag, Am, Cd, Co and Zn in seabream eggs during 65 h of development and retention by newly hatched and 7 h-old larvae maintained in clean seawater, respectively, and 2) investigate the effects of elevated pCO₂ on the bioconcentration efficiencies of these elements in eggs. Besides differing in terms of maximal concentration factors values, the uptake kinetics showed element-specific patterns with Am being linearly bioconcentrated and Co and Zn showing a saturation state equilibrium. The ^110mAg and ¹⁰⁹Cd uptake kinetics shared a two-phases pattern being best described by a saturation equation during the first 24 h of development, and then an exponential loss of accumulated elements although the radiotracer concentrations in the surrounding water remained constant. At hatching time, the radioactivity of ^110mAg was the highest among radiotracers detected in the larvae. After 7 h in depuration conditions, 60% of this metal was still detected whereas ²⁴¹Am, ⁶⁰Co and ⁶⁵Zn were almost totally lost, suggesting an efficient incorporation of Ag in the embryo during the egg development. Finally, this study brought first qualitative data on the effect of pCO₂/pH on metal bioconcentration in eggs, raising the need to unravel chemical and biological processes to predict a potential shift of the toxicity of environmental contamination of fish early life stages with future ocean change.

Metal bioaccumulation and detoxification processes in cephalopods: A review

In recent decades, cephalopods have been shown to have very high capacities to accumulate most trace elements, regardless of whether they are essential (e.g., Cu and Zn) or non-essential (e.g., Ag and Cd). Among the different pathways of exposure to trace elements, the trophic pathway appears to be the major route of assimilation for numerous metals, including Cd, Co, Hg and Zn. Once assimilated, trace elements are distributed in the organism, accumulating in storage organs. The digestive gland is the main organ in which many trace elements accumulate, whichever of the exposure pathway. For example, this organ can present Cd concentrations reaching hundreds to thousands of ppm for some species, even though the digestive gland represents only a small proportion of the total mass of the animal. Such a specific organotropism towards the digestive gland of both essential and non-essential elements, regardless of the exposure pathway, poses the question of the detoxification processes evolved by cephalopods in order to sustain these high concentrations. This paper reviews the current knowledge on the bioaccumulation of trace elements in cephalopods, the differences in pharmaco-dynamics between organs and tissues, and the detoxification processes they use to counteract trace element toxicity. A peculiar focus has been done on the bioaccumulation within the digestive gland by investigating the subcellular locations of trace elements and their protein ligands.

Pre-hatching fluoxetine-induced neurochemical, neurodevelopmental, and immunological changes in newly hatched cuttlefish

Embryonic and early postembryonic development of the cuttlefish Sepia officinalis (a cephalopod mollusk) occurs in coastal waters, an environment subject to considerable pressure from xenobiotic pollutants such as pharmaceutical residues. Given the role of serotonin in brain development and its interaction with neurodevelopmental functions, this study focused on fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI, antidepressant). The goal was to determine the effects of subchronic waterborne FLX exposure (1 and 10 μg L(-1)) during the last 15 days of embryonic development on neurochemical, neurodevelopmental, behavioral, and immunological endpoints at hatching. Our results showed for the first time that organic contaminants, such as FLX, could pass through the eggshell during embryonic development, leading to a substantial accumulation of this molecule in hatchlings. We also found that FLX embryonic exposure (1 and 10 μg L(-1)) (1) modulated dopaminergic but not serotonergic neurotransmission, (2) decreased cell proliferation in key brain structures for cognitive and visual processing, (3) did not induce a conspicuous change in camouflage quality, and (4) decreased lysozyme activity. In the long term, these alterations observed during a critical period of development may impair complex behaviors of the juvenile cuttlefish and thus lead to a decrease in their survival. Finally, we suggest a different mode of action by FLX between vertebrate and non-vertebrate species and raise questions regarding the vulnerability of early life stages of cuttlefish to the pharmaceutical contamination found in coastal waters.

Subchronic effects of cadmium on the gonads, expressions of steroid hormones and sex-related genes in tilapia Oreochromis niloticus

Cadmium (Cd) is one of the most toxic heavy metals in aquatic ecosystem which affects fish health and aquaculture. In the present study, we examined the bioaccumulation of Cd in the gonads of tilapia via dissolved and dietary routes. We evaluated the subchronic effects of Cd on the histology of gonads, steroid hormone levels and sex-related gene expressions in tilapia. In addition, we also studied maternal transfer of Cd. Our results indicated that Cd was accumulated significantly in both ovary and testis from both exposure routes. Histopathological analysis showed that Cd induced ovary and testis injuries. Estradiol levels were significantly increased in dissolved Cd exposed female fish. In addition, the Cd exposure displayed different effects on gene expressions in gonads. In females, the estrogen receptor (ERα) was stimulated in dissolved Cd-exposed fish at 70.32 and 143.78 μg/L for 30 days and in fish at 143.78 μg/L for 60 days. Vitellogenin expression was significantly down-regulated in the ovary of dissolved Cd-exposed fish. In testis, GR expression was elevated after 60 days of dissolved Cd and dietary exposure. Furthermore, Cd level was significantly higher in the eggs than that in the fry. Our results demonstrated that both dissolved and dietary Cd exposures affected gonad development by altering steroid hormone levels and sex-related gene expressions in tilapia.

Understanding the cephalopod immune system based on functional and molecular evidence

Cephalopods have the most advanced circulatory and nervous system among the mollusks. Recently, they have been included in the European directive which state that suffering and pain should be minimized in cephalopods used in experimentation. The knowledge about cephalopod welfare is still limited and several gaps are yet to be filled, especially in reference to pathogens, pathologies and immune response of these mollusks. In light of the requirements of the normative, in addition to the ecologic and economic importance of cephalopods, in this review we update the work published to date concerning cephalopod immune system. Significant advances have been reached in relation to the characterization of haemocytes and defensive mechanisms comprising cellular and humoral factors mainly, but not limited, in species of high economic value like Sepia officinalis and Octopus vulgaris. Moreover, the improvement of molecular approaches has helped to discover several immune-related genes/proteins. These immune genes/proteins include antimicrobial peptides, phenoloxidases, antioxidant enzymes, serine protease inhibitor, lipopolysaccharide-induced TNF-α factor, Toll-like receptors, lectins, even clusters of differentiation among others. Most of them have been found in haemocytes but also in gills and digestive gland, and the characterization as well as their precise role in the immune response of cephalopods is still pending to be elucidated. The assessment of immune parameters in cephalopods exposed to contaminants is just starting, but the negative impact of some pollutants on the immune response of the common octopus has been reported. This review summarizes the current status of our knowledge about the cephalopod immune system that seems to be far from simply. On the contrary, the advances gained to date point out a complex innate immunity in cephalopods.

Physiological perturbations in juvenile cuttlefish Sepia officinalis induced by subchronic exposure to dissolved zinc

Although cephalopod early life stage development often occurs in coastal areas where contamination is real and continuous, the physiological perturbations induced by contaminants have been rarely investigated. This study focused on the Zn as it is one of the trace metals the most concentrated in coastal waters, worldwide. As Zn-tolerance limits were unknown in juvenile Sepia officinalis, the aim of this study was to estimate the threshold inducing mortality during the 2-first weeks post-hatching, and to determine its sensitivity using digestive and immune enzymatic assays, as well as growth and behavior follow-up during the first 5weeks post-hatching. Our study highlighted a Zn-mortality threshold lying between 185 and 230μgl(-1), and growth reductions occurring after 5-week at 108μgl(-1) and above, associated with enzymatic perturbations. These results underline a relatively important sensitivity of juvenile cuttlefish to Zn, pointed out by a wide diversity of biomarkers.

Trace metal concentrations in post-hatching cuttlefish Sepia officinalis and consequences of dissolved zinc exposure

In this study, we investigated the changes of 13 trace metal and metalloid concentrations (i.e. Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, V, Zn) and their subcellular fractionation in juvenile cuttlefish Sepia officinalis reared in controlled conditions between hatching and 2 months post-hatching. In parallel, metallothionein concentrations were determined. Our results highlighted contrasting changes of studied metals. Indeed, As and Fe concentrations measured in hatchlings suggested a maternal transfer of these elements in cuttlefish. The non-essential elements Ag and Cd presented the highest accumulation during our study, correlated with the digestive gland maturation. During the 6 first weeks of study, soluble fractions of most of essential trace metals (i.e. Co, Cr, Cu, Fe, Se, Zn) slowly increased consistently with the progressive needs of cuttlefish metabolism during this period. In order to determine for the first time in a cephalopod how metal concentrations and their subcellular distributions are impacted when the animals are trace metal-exposed, we studied previously described parameters in juveniles exposed to dissolved Zn at environmental (i.e. 50 μg l(-1)) and sublethal (i.e. 200 μg l(-1)) levels. Moreover, oxidative stress (i.e. glutathione S-transferase (GST), superoxide dismutase (SOD) and catalase activities, and lipid peroxidation (LPO)) was assessed in digestive gland and gills after 1 and 2 months exposures. Our results highlighted no or low ability of this stage of life to regulate dissolved Zn accumulation during the studied period, consistently with high sensitivity of this organism. Notably, Zn exposures caused a concentration-dependent Mn depletion in juvenile cuttlefish, and an increase of soluble fraction of Ag, Cd, Cu without accumulation modifications, suggesting substitution of these elements (i.e. Mn, Ag, Cd, Cu) by Zn. In parallel, metallothionein concentrations decreased in individuals most exposed to Zn. Finally, no perturbations in oxidative stress management were detected in gills, whereas modifications of GST, SOD and catalase activity levels were recorded in digestive gland, resulting in an increase of LPO content after a 6-week exposure to low Zn concentration. Altogether, these perturbations are consistent with previously described high sensitivity of juvenile cuttlefish towards Zn. Our results underlined the need to study deeply contamination impact on this animal at this stage of life.

Transcriptional and biochemical effects of cadmium and manganese on the defense system of Octopus vulgaris paralarvae

Due to anthropogenic activities the relative concentrations of cadmium and manganese have increased in the marine environment. Cephalopods are able to accumulate such metals and, as inhabitant of coastal waters, Octopus vulgaris is continuously exposed to anthropogenic activities. Since no study is available on the effects of heavy metals at molecular level in developing octopuses, herein we exposed 1-day-old paralarvae for 24 h to 10, 100, and 1000 μg/L of CdCl2 or MnCl2. Cd exerted a concentration-dependent inhibition of survival and a reduction in growth rate was shown while Mn exposure did not affect the survival rate even at the highest concentrations. Gene expression profiles of hsp70, sod, cat, and gst genes were analyzed by quantitative real-time PCR and defined patterns of transcription were observed. Moreover posttranscriptional analyses were also performed suggesting the impairment of metabolic functions, under strong oxidative conditions (as occurred in paralarvae exposed to Cd) or the complete detoxification events (as occurred in paralarvae exposed to Mn).

Cryptic and biochemical responses of young cuttlefish Sepia officinalis exposed to environmentally relevant concentrations of fluoxetine

Antidepressants released in the environment have the potential to generate neural disrupting effects in non-target organisms, yet their putative effects on behaviors have never been studied in cephalopod molluscs. This study assessed the impact of the antidepressant fluoxetine (FLX) on the efficiency of cryptic behaviors (body patterns on uniform, checkerboard and sandy substrates), locomotor activity, and brain chemistry in young cuttlefish exposed to environmental concentrations (1 and 100ngL(-1) of FLX) during the perinatal period. Behavioral responses of cuttlefish were monitored at hatching and two weeks later, and brain monoamine contents were quantified at one month of age. FLX significantly altered the camouflage efficiencies on uniform and sandy backgrounds only at the lowest concentration, but not at 100ngL(-1). Hatchlings exposed to 1ngL(-1) of FLX exhibited a duration exposure-dependent decrease in the uniform camouflage. They also showed a significant increase of the frequency of sand digging behaviors which might make them highly visible to predators in nature. When tested again two weeks later, cuttlefish seemed to have recovered and no more behavioral alterations were observed showing a transitory effect of the antidepressant. FLX did not affect the levels of serotonin, norepinephrine and their metabolites; however, it seemed to influence dopaminergic activity between the two FLX-exposed groups. The results show for the time that environmentally realistic concentrations of a single SSRI significantly impair the cryptic performances of newly hatched cuttlefish, and may ultimately reduce their chance for survival.

Cephalopods in neuroscience: regulations, research and the 3Rs

Cephalopods have been utilised in neuroscience research for more than 100 years particularly because of their phenotypic plasticity, complex and centralised nervous system, tractability for studies of learning and cellular mechanisms of memory (e.g. long-term potentiation) and anatomical features facilitating physiological studies (e.g. squid giant axon and synapse). On 1 January 2013, research using any of the about 700 extant species of "live cephalopods" became regulated within the European Union by Directive 2010/63/EU on the "Protection of Animals used for Scientific Purposes", giving cephalopods the same EU legal protection as previously afforded only to vertebrates. The Directive has a number of implications, particularly for neuroscience research. These include: (1) projects will need justification, authorisation from local competent authorities, and be subject to review including a harm-benefit assessment and adherence to the 3Rs principles (Replacement, Refinement and Reduction). (2) To support project evaluation and compliance with the new EU law, guidelines specific to cephalopods will need to be developed, covering capture, transport, handling, housing, care, maintenance, health monitoring, humane anaesthesia, analgesia and euthanasia. (3) Objective criteria need to be developed to identify signs of pain, suffering, distress and lasting harm particularly in the context of their induction by an experimental procedure. Despite diversity of views existing on some of these topics, this paper reviews the above topics and describes the approaches being taken by the cephalopod research community (represented by the authorship) to produce "guidelines" and the potential contribution of neuroscience research to cephalopod welfare.

A study of the electrical polarization of Sepia officinalis yolk envelope, a role for Na(+)/K(+)-ATPases in osmoregulation?

The cuttlefish Sepia officinalis mate and spawn in the intertidal zone where eggs are exposed during low tide to osmotic stress. Embryonic outer yolk sac is a putative site for osmoregulation of young S. officinalis embryos. By using electrophysiological recordings and immunostaining we showed, (i) that the chorion is only a passive barrier for ions, since large molecules could not pass through it, (ii) that a complex transepithelial potential difference occurs through the yolk epithelium, (iii) that ionocyte-like cells and Na⁺/K⁺-ATPases were localized in the yolk epithelium and (iv) that ouabain sensitive Na⁺/K⁺-ATPase activity could participate to this yolk polarization. These data warrant further study on the role of ion transport systems of this epithelium in the osmoregulation processes in S. officinalis embryos.

A review of the factors influencing spawning, early life stage survival and recruitment variability in the common cuttlefish (Sepia officinalis)

Global landings of cephalopods (cuttlefish, squid and octopus) have increased dramatically over the past 50 years and now constitute almost 5% of the total world's fisheries production. At a time when landings of many traditional fin-fish stocks are continuing to experience a global decline as a result of over-exploitation, it is expected that fishing pressure on cephalopod stocks will continue to rise as the fishing industry switch their focus onto these non-quota species. However, long-term trends indicate that landings may have begun to plateau or even decrease. In European waters, cuttlefish are among the most important commercial cephalopod resource and are currently the highest yielding cephalopod group harvested in the north-east Atlantic, with the English Channel supporting the main fishery for this species. Recruitment variability in this short-lived species drives large fluctuations in landings. In order to provide sustainable management for Sepia officinalis populations, it is essential that we first have a thorough understanding of the ecology and life history of this species, in particular, the factors affecting spawning, early life stage (ELS) survival and recruitment variability. This review explores how and why such variability exists, starting with the impact of maternal effects (e.g. navigation, migration and egg laying), moving onto the direct impact of environmental variation on embryonic and ELSs and culminating on the impacts that these variations (maternal and environmental) have at a population level on annual recruitment success. Understanding these factors is critical to the effective management of expanding fisheries for this species.

Radioisotopes demonstrate the contrasting bioaccumulation capacities of heavy metals in embryonic stages of cephalopod species

Cephalopods play a key role in many marine trophic food webs and also constitute alternative fishery resources in the context of the ongoing decline in finfish stocks. Most coastal cephalopod species of commercial importance migrate into shallow waters during the breeding season to lay their eggs, and are consequently subjected to coastal contamination. Eggs of common cuttlefish Sepia officinalis, European squid Loligo vulgaris, common octopus Octopus vulgaris and the sepiolid Rossia macrosoma were exposed during embryonic development to dissolved ^110mAg, ¹⁰⁹Cd, ⁶⁰Co, ⁵⁴Mn and ⁶⁵Zn in order to determine their metal accumulation efficiencies and distribution among different egg compartments. Cuttlefish eggs, in which hard shells enclose the embryos, showed the lowest concentration factor (CF) values despite a longer duration of exposure. In contrast, octopus eggs, which are only protected by the chorionic membrane, accumulated the most metal. Uptake appears to be linked to the selective retention properties of the egg envelopes with respect to each element. The study also demonstrated that the octopus embryo accumulated ^110mAg directly from the dissolved phase and also indirectly through assimilation of the contaminated yolk. These results raise questions regarding the potential contrasting vulnerability of early life stages of cephalopods to the metallic contamination of coastal waters.

Effects of ocean acidification on trace element accumulation in the early-life stages of squid Loligo vulgaris

The anthropogenic release of carbon dioxide (CO(2)) into the atmosphere leads to an increase in the CO(2) partial pressure (pCO(2)) in the ocean, which may reach 950 μatm by the end of the 21st century. The resulting hypercapnia (high pCO(2)) and decreasing pH ("ocean acidification") are expected to have appreciable effects on water-breathing organisms, especially on their early-life stages. For organisms like squid that lay their eggs in coastal areas where the embryo and then paralarva are also exposed to metal contamination, there is a need for information on how ocean acidification may influence trace element bioaccumulation during their development. In this study, we investigated the effects of enhanced levels of pCO(2) (380, 850 and 1500 μatm corresponding to pH(T) of 8.1, 7.85 and 7.60) on the accumulation of dissolved (110m)Ag, (109)Cd, (57)Co, (203)Hg, (54)Mn and (65)Zn radiotracers in the whole egg strand and in the different compartments of the egg of Loligo vulgaris during the embryonic development and also in hatchlings during their first days of paralarval life. Retention properties of the eggshell for (110m)Ag, (203)Hg and (65)Zn were affected by the pCO(2) treatments. In the embryo, increasing seawater pCO(2) enhanced the uptake of both (110m)Ag and (65)Zn while (203)Hg showed a minimum concentration factor (CF) at the intermediate pCO(2). (65)Zn incorporation in statoliths also increased with increasing pCO(2). Conversely, uptake of (109)Cd and (54)Mn in the embryo decreased as a function of increasing pCO(2). Only the accumulation of (57)Co in embryos was not affected by increasing pCO(2). In paralarvae, the CF of (110m)Ag increased with increasing pCO(2), whereas the (57)Co CF was reduced at the highest pCO(2) and (203)Hg showed a maximal uptake rate at the intermediate pCO(2). (54)Mn and (65)Zn accumulation in paralarvae were not significantly modified by hypercapnic conditions. Our results suggest a combined effect of pH on the adsorption and protective properties of the eggshell and of hypercapnia on the metabolism of embryo and paralarvae, both causing changes to the accumulation of metals in the tissues of L. vulgaris.

Decreased dissolution of ZnO by iron doping yields nanoparticles with reduced toxicity in the rodent lung and zebrafish embryos

We have recently shown that the dissolution of ZnO nanoparticles and Zn(2+) shedding leads to a series of sublethal and lethal toxicological responses at the cellular level that can be alleviated by iron doping. Iron doping changes the particle matrix and slows the rate of particle dissolution. To determine whether iron doping of ZnO also leads to lesser toxic effects in vivo, toxicity studies were performed in rodent and zebrafish models. First, we synthesized a fresh batch of ZnO nanoparticles doped with 1-10 wt % of Fe. These particles were extensively characterized to confirm their doping status, reduced rate of dissolution in an exposure medium, and reduced toxicity in a cellular screen. Subsequent studies compared the effects of undoped to doped particles in the rat lung, mouse lung, and the zebrafish embryo. The zebrafish studies looked at embryo hatching and mortality rates as well as the generation of morphological defects, while the endpoints in the rodent lung included an assessment of inflammatory cell infiltrates, LDH release, and cytokine levels in the bronchoalveolar lavage fluid. Iron doping, similar to the effect of the metal chelator, DTPA, interfered in the inhibitory effects of Zn(2+) on zebrafish hatching. In the oropharyngeal aspiration model in the mouse, iron doping was associated with decreased polymorphonuclear cell counts and IL-6 mRNA production. Doped particles also elicited decreased heme oxygenase 1 expression in the murine lung. In the intratracheal instillation studies in the rat, Fe doping was associated with decreased polymorphonuclear cell counts, LDH, and albumin levels. All considered, the above data show that Fe doping is a possible safe design strategy for preventing ZnO toxicity in animals and the environment.

Influence of food on the assimilation of selected metals in tropical bivalves from the New Caledonia lagoon: qualitative and quantitative aspects

The present study aimed at examining the influence of food quality and quantity on the assimilation efficiency (AE) of metals in two abundant bivalves in the New Caledonia lagoon, the oyster Isognomon isognomon and the clam Gafrarium tumidum. Bivalves were exposed via their food to the radiotracers of three metals of concern in New Caledonia ((54)Mn, (57)Co and (65)Zn) under different feeding conditions (phytoplankton species, cell density, and cell-associated metal concentration). When bivalves were fed Heterocapsa triquetra, Emiliania huxleyi and Isochrysis galbana, AE of Mn, Co and Zn was strongly influenced by the phytoplankton species and by the metal considered. In contrast, when fed one given phytoplankton species previously exposed to different concentrations of Co, phytoplankton-associated Co load had no influence on the AE and on the retention time of the metal in both bivalves. Metals ingested with I. galbana displayed generally the highest AE in both bivalve species, except for Mn in clams for which the highest AE was observed for H. triquetra. Influence of food quantity was investigated by exposing bivalves to different cell densities of I. galbana (5 x 10(3), 10(4) or 5 x 10(4) cell ml(-1)). As for food quality, food quantity was found to influence AE of Mn, Co and Zn, the highest AE being observed when bivalves were fed the lowest cell density. Overall, results indicate that the two bivalve species are able to adjust their feeding strategies according to the food conditions prevailing in their environment.

Biokinetics of Hg and Pb accumulation in the encapsulated egg of the common cuttlefish Sepia officinalis: radiotracer experiments

Uptake and depuration kinetics of dissolved (203)Hg and (210)Pb were determined during the entire embryonic development of the eggs of the cuttlefish, Sepia officinalis (50d at 17 degrees C). (203)Hg and (210)Pb were accumulated continuously by the eggs all along the development time reaching load/concentration ratio (LCR) of 467+/-43 and 1301+/-126g, respectively. During the first month, most of the (203)Hg and (210)Pb remained associated with the eggshell indicating that the latter acted as an efficient shield against metal penetration. From this time onwards, (203)Hg accumulated in the embryo, indicating that it passed through the eggshell, whereas (210)Pb did not cross the chorion during the whole exposure time. It also demonstrated that translocation of Hg associated with the inner layers of the eggshell is a significant source of exposure for the embryo. This study highlighted that the maturing embryo could be subjected to the toxic effects of Hg in the coastal waters where the embryonic development is taking place.

Phenoloxidase activation in the embryo of the common cuttlefish Sepia officinalis and responses to the Ag and Cu exposure

The prophenoloxidase (proPO) system catalyzing the melanin production is considered as implicated in the innate immune system in invertebrates. The phenoloxidase (PO)-like activity was detected in the cuttlefish embryo sampled at the end of the organogenesis and few hours before hatching. Various modulators of the PO activity were used to assess the triggering of the proPO activating system. The results demonstrated the evidence of a true PO activity in the cuttlefish embryo. However, SDS and LPS granted contrasting effects on the PO-like activity between the developmental stages suggesting a progressive maturation of the proPO system from the embryonic to the juvenile stages. In eggs exposed to dissolved trace metals all along the embryonic development, Ag (1.2 microg L(-1)) inhibited the PO-like activity in the cuttlefish embryo except at hatching time, suggesting the synthesis of a new "juvenile" form of the PO enzyme. In similar conditions as for Ag, Cu (230 microg L(-1)) stimulated and then inhibited the PO-like activity according to a progressive metal accumulation within the egg and suggesting the occurrence of a threshold, above which the toxicity of the essential metal reduced the PO activity.

First experiments on the maternal transfer of metals in the cuttlefish Sepia officinalis

The aim of this study was to provide a first insight on the incorporation of eight metals in the eggs of the cuttlefish Sepia officinalis via maternal transfer, using radiotracer techniques ((110m)Ag, (241)Am, (109)Cd, (60)Co, (134)Cs, (54)Mn, (75)Se and (65)Zn). The cuttlefish was fed daily with radiolabelled crabs for two weeks; it then started to spawn every three days. Among the eight tracers, only (110m)Ag, (75)Se and (65)Zn were significantly transferred to the eggs. The radiotracer distribution among the egg compartments showed that (75)Se and (65)Zn were accumulated mainly in the vitellus whereas (110m)Ag was found in similar proportion in the vitellus and the eggshell. During the embryonic development, (75)Se and (65)Zn contained in the vitellus were progressively transferred to the embryo, likely to supply its metabolic needs in these essential elements. Although it has no known biological functions, Ag contained in both vitellus and eggshell was also transferred to the embryo. Overall, our results showed that transfer of Ag, Se, and Zn does actually occur from a female cuttlefish to its eggs, at least during the last two weeks before spawning.