Toxicity of perfluoroalkyl substances (PFAS) toward embryonic stages of mahi-mahi (Coryphaena hippurus).

Perfluoroalkyl substances (PFAS) are highly persistent organic pollutants that have been detected in a wide array of environmental matrices and, in turn, diverse biota including humans and wildlife wherein they have been associated with a multitude of toxic, and otherwise adverse effects, including ecosystem impacts. In the present study, we developed a toxicity assay for embryonic stages of mahi-mahi (Coryphaena hippurus), as an environmentally relevant pelagic fish species, and applied this assay to the evaluation of the toxicity of "legacy" and "next-generation" PFAS including, respectively, perfluorooctanoic acid (PFOA) and several perfluoroethercarboxylic acids (PFECA). Acute embryotoxicity, in the form of lethality, was measured for all five PFAS toward mahi-mahi embryos with median lethal concentrations (LC50) in the micromolar range. Consistent with studies in other similar model systems, and specifically the zebrafish, embryotoxicity in mahi-mahi generally (1) correlated with fluoroalkyl/fluoroether chain length and hydrophobicity, i.e., log P, of PFAS, and thus, aligned with a role of uptake in the relative toxicity; and (2) increased with continuous exposure, suggesting a possible role of development stage specifically including a contribution of hatching (and loss of protective chorion) and/or differentiation of target systems (e.g., liver). Compared to prior studies in the zebrafish embryo model, mahi-mahi was significantly more sensitive to PFAS which may be related to differences in either exposure conditions (e.g., salinity) and uptake, or possibly differential susceptibility of relevant targets, for the two species. Moreover, when considered in the context of the previously reported concentration of PFAS within upper sea surface layers, and co-localization of buoyant eggs (i.e., embryos) and other early development stages (i.e., larvae, juveniles) of pelagic fish species to the sea surface, the observed toxicity potentially aligns with environmentally relevant concentrations in these marine systems. Thus, impacts on ecosystems including, in particular, population recruitment are a possibility. The present study is the first to demonstrate embryotoxicity of PFAS in a pelagic marine fish species, and suggests that mahi-mahi represents a potentially informative, and moreover, environmentally relevant, ecotoxicological model for PFAS in marine systems.

Apparent bioaccumulation of cylindrospermopsin and paralytic shellfish toxins by finfish in Lake Catemaco (Veracruz, Mexico).

Compared to the well-characterized health threats associated with contamination of fish and shellfish by algal toxins in marine fisheries, the toxicological relevance of the bioaccumulation of toxins from cyanobacteria (blue-green algae), as the primary toxigenic algae in freshwater systems, remains relatively unknown. Lake Catemaco (Veracruz, Mexico) is a small, tropical lake system specifically characterized by a year-round dominance of the known toxigenic cyanobacterial genus, Cylindrospermopsis, and by low, but detectable, levels of both a cyanobacterial hepatotoxin, cylindrospermopsin (CYN), and paralytic shellfish toxins (PSTs). In the present study, we evaluated, using enzyme-linked immunoassay (ELISA), levels of both toxins in several species of finfish caught and consumed locally in the region to investigate the bioaccumulation of, and possible health threats associated with, these toxins as potential foodborne contaminants. ELISA detected levels of both CYN and PSTs in fish tissues from the lake. Levels were generally low (≤ 1 ng g(-1) tissue); however, calculated bioaccumulation factors (BAFs) indicate that toxin levels exceed the rather low levels in the water column and, consequently, indicated bioaccumulation (BAF >1). A reasonable correlation was observed between measured bioaccumulation of CYN and PSTs, possibly indicating a mutual source of both toxins, and most likely cells of Cylindrospermopsis, the dominant cyanobacteria in the lake, and a known producer of both metabolites. The potential roles of trophic transport in the system, as well as possible implications for human health with regards to bioaccumulation, are discussed.

Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae.

The estuarine genus Pfiesteria has received considerable attention since it was first identified and proposed to be the causative agent of fish kills along the mid-Atlantic coast in 1992. The presumption has been that the mechanism of fish death is by release of one or more toxins by the dinoflagellate. In this report, we challenge the notion that Pfiesteria species produce ichthyotoxins. Specifically, we show that (i) simple centrifugation, with and without ultrasonication, is sufficient to "detoxify" water of actively fish-killing cultures of Pfiesteria shumwayae, (ii) organic extracts of lyophilized cultures are not toxic to fish, (iii) degenerate primers that amplify PKS genes from several polyketide-producing dinoflagellates failed to yield a product with P. shumwayae DNA or cDNA, and (iv) degenerate primers for NRPS genes failed to amplify any NRPS genes but (unexpectedly) yielded a band (among several) that corresponded to known or putative PKSs and fatty acid synthases. We conclude that P. shumwayae is able to kill fish by means other than releasing a toxin into bulk water. Alternative explanations of the effects attributed to Pfiesteria are suggested.

Apoptosis of rat kidney cells after 241-americium administration.

Tumors induction by americium is well known but there are no data on the biological effects of this radionucleide at subcellular level. In order to study the possible ultrastructural lesions induced by this element, a group of rats were injected with 241-Americium-citrate (9 kBq), once a week for five weeks and sacrificed 7 days after the last injection. We describe the alterations observed in the cortex kidney using cytochemical (TUNEL reaction) and histochemical (PAS staining) methods for light microscopy as well as electron microscopy techniques. Various types of lesions were detected: condensation of nuclear chromatine, fragmentation of the nuclei, swollen mitochondria, disappearance of mitochondrial crests and skrinking of the cytoplasm. This study clearly demonstrated the induction of apoptosis by americium in rat cortex kidney cells.

Ultrastructural apoptotic lesions induced in rat thymocytes after borax ingestion.

BACKGROUND: Apoptosis has gained increasing attention in recent years. Several chemical compounds induce apoptotic lesions in the thymus. Male Wistar rats received 2000 ppm of borax (Na2B4O7.10H2O) in their food for 16 days. The rats were sacrificed 2, 5, 9, 12, 19, 21, 26 and 28 days after the beginning of treatment. Thymus samples of all rats were taken. A Philips EM 300 electron microscopy was used to study the ultrastructural morphology. Serious nuclear and cytoplasmic lesions were observed. Moreover, numerous macrophages containing apoptotic cells were present in the thymus. The alterations were observed from the 2nd to the 28th day. The extent of damage was much more important in the rats sacrificed 21, 26 and 28 days after borax ingestion.

Role of alveolar macrophage lysosomes in metal detoxification.

The intracellular behaviour of different toxic mineral elements inhaled as soluble aerosols or as insoluble particles was studied in the rat by electron microscopy, electron probe microanalysis, and electron microdiffraction. This study showed that, after inhalation, aerosols of soluble elements like cerous chloride, chromic chloride, uranyl nitrate, and aluminium chloride, are concentrated in the lysosomes of alveolar macrophages and are precipitated in the lysosomes in the form of insoluble phosphate, probably due to the activity of acid phosphatase (intralysosomial enzyme). Also, after inhalation of crystalline particles that are insoluble or poorly soluble in water such as the illites (phyllosilicates), ceric oxides (opaline), and industrial uranium oxides (U3O8), the small crystals are captured by the alveolar macrophage lysosomes and transformed over time into an amorphous form. This structural transformation is associated with changes in the chemical nature of particles inhaled in the oxide form. Microanalysis of amorphous deposits observed after inhalation of uranium or ceric oxides has shown that they contain high concentrations of phosphorus associated with the initial elements cerium and uranium. These different processes tend to limit the diffusion of these toxic elements within the organism, whether they are inhaled in soluble form or not.

Early ultrastructural lesions of apoptosis induced in vivo in two varieties of tissues (thymus and kidneys) after a single whole-body-gamma irradiation of adult mice.

Three groups of adult Swiss albino female mice with an average body weight of 20 grams were exposed to a whole-body irradiation by 137-cesium gamma rays at 2, 4 and 6 Gy (1.4 Gy/min.). For all groups, samples of thymus and kidney were taken 15 min., 2, 6 and 24 hrs. after irradiation and immediately prepared for observation by electron microscopy. In the thymus the earliest significant ultrastructural lesions are observed in the nuclei from the fifteenth minute. These lesions are characterized by condensation of chromatin, convolution and fragmentation of nuclei. Alteration of mitochondria and clarification of cytoplasm in a number of thymocytes are also observed depending on the dose of radiation. These lesions increased according to the length of the post-irradiation period and after six hrs. a great number of macrophages are observed in the thymus. Most often a single macrophage, contain several apoptotic thymocytes, with a maximum number up to eight. In the kidney, serious lesions were observed, affecting both, the nucleus and the cytoplasm of the proximal convoluted tubule cells (PCT). However in these cells, the most significant and earliest lesions consist of wide cytoplasmic clarifications, severe mitochondrial damages, associated with architectural modifications of the brush border and the beta-cytomembranes. These damaged cells have been observed to occur close to normal ultrastructural cells. Less significant ultrastructural alterations are also noticed in different varieties of glomerular cells. In contrast to the serious lesions of the PCT and glomerular cells, no ultrastructural alteration were observed in the distal tubule.

Subcellular localization of neptunium-237 in lung and kidney after intratracheal administration in the rat: an ultrastructural and microanalytical study.

Chronic intratracheal administration of 237Np to rate was performed during 6 weeks. The total dose administered was 45.8 kBq. Two methods, electron microscopy and electron probe X-ray microanalysis, were used to determine the intracellular sites of localization of 237Np. Clusters of dense granules were observed in nuclei of pneumocytes and proximal tubular cells of the kidneys. These clusters have been shown to contain neptunium associated with phosphorus, sulfur and calcium. Alterations of nuclei and ultrastructural cytoplasmic lesions were observed. The absorbed doses in lungs and kidneys were very low. These results suggest that the chemical toxicity of 237Np is more important than its radiological toxicity.

The role of lysosomes in the selective concentration of mineral elements. A microanalytical study.

The role of the lysosome during the intracellular concentration of diverse mineral elements has been evidenced by the electron probe X-ray microanalysis (EPMA). This highly sensitive technique allows an in situ chemical analysis of any chemical element with an atomic number greater than 11, present in ultra-thin tissue sections. Therefore, it has been demonstrated by using this EPMA that 21 out of the 92 elements of the periodic table, once injected in a soluble form, were selectively concentrated within lysosomes of several types of mammalian cells. Amongst these 21 elements, 15 are concentrated and precipitated in an insoluble from in association with phosphorus whereas the other 6 are precipitated in association with sulphur. Amongst the 15 elements which precipitate with phosphorus in lysosomes, there are: 3 group IIIB elements of the periodic system, (aluminium, gallium and indium); the rare-earth elements (cerium, gadolinium, lanthanum, thulium and samarium); 2 group IVA elements (hafnium and zirconium), two actinides (uranium and thorium) and elements such as chromium and niobium. The 6 elements which precipitate with sulphur comprise the 3 group VIII elements of the classification (nickel, palladium, platinum) and the 3 group IB elements (copper, silver and gold). The mechanisms responsible for this selective concentration involve enzymatic processes and predominantly acid phosphatases for elements precipitating as phosphates and arylsulfatases for elements precipitating with sulphur.

Role of alveolar macrophages in the dissolution of two different industrial uranium oxides.

This study was aimed at assessing and understanding some mechanisms involved in the intracellular particle transformation of two uranium oxides (U3O8 and UO2 + Umetal) produced by a new isotopic enrichment plant using laser technology. Instillations were conducted on rats with both uranium compounds and alveolar macrophages were harvested at different dates and prepared in order to be studied using transmission electron microscopy and electron energy loss spectrometry (EELS). The presence of particles in the cells was observed from the first day after instillation, and crystalline needles of uranyl phosphate appeared in the cytoplasm of the cells. These needles were more numerous after instillation with the mixture UO2 + Umetal than after administration of U3O8 and may be correlated with the higher solubility of UO2 + Umetal observed in vitro. The formation of insoluble needles in lysosomes is consistent with the insolubilisation of uranium observed after phagocytosis by alveolar macrophages.

Intranuclear dense bodies after metal intoxication: a review of ultrastructural and microanalytical findings.

Abnormal intranuclear dense bodies are observed in several varieties of cells after intoxication by four varieties of metals: lead, bismuth, beryllium and neptumium. These inclusions have been studied by two microanalytical methods: Electron probe X-ray microanalysis (EPMA) and ion microscopy. A strong similarity has been observed in the ultrastructure of the dense bodies produced several weeks after beryllium and neptunium intoxication although there exists an important discrepancy between both elements concerning their physical, chemical and physico-chemical characteristics. Furthermore, these dense bodies are observed in the same varieties of cells (tubular proximal cells of kidneys, hepatocytes, pneumocytes). Intranuclear dense bodies produced by lead are also observed in the same types of cells, where they showed similar ultrastructure patterns as beryllium and neptunium inclusions but only after a long period, several years, after a chronic intoxication. The ultrastructure of the dense bodies produced by bismuth are clearly distinct from beryllium, neptunium or lead inclusions. Beryllium, neptunium and lead have been detected by EPMA or ion microscopy in the corresponding dense bodies although the real presence of bismuth remains to be confirmed in the nuclear dense bodies produced by this element.

[Early ultrastructural lesions of kidney cells after intravenous administration of 239 plutonium citrate in rats]. / Lésions ultrastructurales précoces des cellules rénales après administration intraveineuse de citrate de plutonium 239 chez le rat.

After intravenous administration of (5 x 2.3 kBq and 5 x 9.25 kBq) plutonium citrate in adult male Sprague Dawley rats, their kidneys are withdrawn and prepared for observation under a transmission electron microscope. Seven days after the first injections, deep cellular alterations are observed in the proximal convoluted tubules. These alterations are mainly mitochondrial. The affected mitochondria are of swollen aspect and have their cristae partially or completely destroyed. Nevertheless within the same tubule we observe non altered cells directly in contact with deeply altered cells. In all the cases the lysosomes of the altered cells appear to be perfectly normal. The cell nuclei are mostly unaltered but a few cases of nuclear fragmentation exist. We also notice some architectural modifications in the brush border and in the betacytomembranes of the proximal convoluted tubule. Equally important mitochondrial alterations are also noticed in the different varieties of glomerular cells. We observe no other glomerular alterations. The major subcellular alterations in the proximal convoluted tubules and in the different varieties of glomerular cells deeply contrast with the distal convoluted tubules which are found to be totally unaltered. These mitochondrial alterations may be due to the alpha particle disintegration of plutonium which may either directly react with the mitochondria or, through the products of radiolysis of water react with the mitochondria respiration process. However the direct chemotoxicity of plutonium cannot be neglected.

Intranuclear sites of Np 237 in mammalian cells: a study using electron microscopy and electron probe microanalysis.

Two methods, electron microscopy and wavelength dispersive electron probe microanalysis, were used to determine the intracellular sites and chemical form of concentrations of neptunium nitrate 237 after chronic intoxication by the intraperitoneal route in two organs in the rat known to concentrate this element (kidney, liver). Abnormal intranuclear formations in the form of clusters of dense granules containing neptunium, phosphorus, sulphur, and calcium were found in the nuclei of kidney proximal tubule cells and hepatocytes. These formations had a maximum diameter of the order of 2 microns and were located in the central part of the nucleus, away from the nucleolus and peripheral chromatin. Serious nuclear and cytoplasmic ultrastructural lesions are often associated in cells containing neptunium inclusions. The absorbed doses in the kidney and the liver were very low. A relationship between these abnormal intranuclear structures and the carcinogenic effect of neptunium remains to be clarified. This effect is related more probably to the chemical toxicity of Np 237.

Scanning ion microscopy mapping of basement membrane elements and arterioles in the kidney after selenium-silver interaction.

The effects of selenium and silver salts was studied by scanning ionic microscopy during experimental argyria mapping of the different basement membrane elements. The ionic microscope (IMS 4F) was equipped with a high resolution spectrometer giving high spatial resolution on the image obtained. After long-term treatment with silver salt alone, silver and sulphur deposits were observed in the membranes. After administration of selenium and silver salt, it was possible to map nitrogen, sulphur, selenium and silver to the glomerular basement membrane as well as to the wall of the kidney arterioles. In the latter, sulphur, selenium and silver were localized only in the elastic laminae of the walls. This process of precipitation of silver deposits in the membrane can be interpreted as process of selenium "detoxification" of the organism.

Subcellular localization of gadolinium injected as soluble salt in rats: a microanalytical study.

The rare earth gadolinium (Gd) is used in modern industry. Solubilized DTPA Gd and DOTA Gd complexes are used as contrast media in nuclear magnetic resonance imaging. In order to determine the subcellular localization of Gd, rats were injected intraperitoneally with Gd nitrate. Two microanalytic methods, ion microanalysis and electron microprobe, enabled the distribution and the intracellular localization of Gd to be determined in the liver, spleen, bone marrow, kidneys and lung. The results showed: a) a punctual distribution of Gd in the tissues (liver, spleen, bone marrow and lung) as observed by ion microscopy; b) a selective concentration of Gd in the lysosomes of macrophages of the liver (hepatocytes), spleen (macrophages), bone marrow (macrophages) and lung (phagocyte cells), as determined by electron probe X-ray microanalysis. In all these sites the Gd is associated to phosphorus. Results are compared to those found for other rare earths and metal elements.

Interaction of selenium with copper, silver, and gold salts. Electron microprobe study.

The interaction of selenium with elements of group 1b of the periodic system, i.e. copper, silver, and gold was studied. Electron probe microanalysis was used to detect elements in intracellular organelles. Administration of copper, silver, or gold salts (the latter being used in chrysotherapy) showed that these elements were concentrated in the lysosomes of the liver or kidney in the presence of sulfur. Silver salts were also precipitated in glomerular basement membranes. The action of selenium enhances this intralysosomal process of concentration and precipitation. Sulfur and selenium are detected in the lysosome and this makes identification of the precipitate difficult. The action of selenium, which consists in removing toxic elements from the systemic circulation and concentrating them in the lysosomes, is in most cases beneficial for the organism. This mechanism, which has already been studied for arsenic, is extended in this study to other elements.

Subcellular localization of gold in suprarenal testicle and thyroid glands after injection of allochrysine in rats.

Gold injected under the form of anti-rheumatoid polyarthritis soluble solutions provokes, as observed by electron microscope, a deposit of crystalline micro-needles in different tissues, like in cells of adrenal and suprarenal glands, in Leydig cells of the testicles, in isolated thyrocytes and in thyroid endothelial cells. They are present as bundles, often of incurvated type, of high electron-density, present in lysosomes, which contain moreover a hyaline, emptied vesicle. These structures are named "aurosomes". The microanalysis, using the MS 46 (Cameca) and the Camebax (MBX) demonstrates that these crystalline structures are composed by gold associated with sulphur, and not with phosphate.

Selenium-arsenic interaction in renal cells: role of lysosomes. Electron microprobe study.

Selenium can modify the toxicity of different elements. Selenium and the element form a complex that is precipitated in the tissues and inhibits the toxicity of the element. We studied the interaction of arsenic and selenium at the subcellular level in rat kidney cells using electronic probe microanalysis that permits detection of elements in the intracellular organelles. This showed that arsenic and selenium are concentrated and precipitated in the lysosomes of the renal cells in the form of insoluble selenide (As2Se). In the long term, the lysosomes and their precipitate are eliminated in the urine. These processes enable the lethal toxicity of arsenic to be inhibited. This intralysosomal concentration and precipitation can serve as a model for the mechanism of interaction of selenium with other elements and can be compared with other mechanisms of concentration and precipitation of elements in the lysosomes.