Evaluation of the Genotoxic and Histological Effects in Neotropical Fish Prochilodus Lacustris (Pisces, Prochilodontidae) in Conservation Area of the Brazilian Northeast.

Human activities significantly impact the aquatic biota in lacustrine environments, leading to negative environmental consequences. Due to this, this study was carried out to evaluate the genotoxic and histological biomarkers in the gills and kidneys of Prochilodus lacustris. The collection of fish and water was conducted in three distinct stations (S1, S2, S3) in an international protected area in northeast Brazil. The histological alterations index was used to assess changes in the gills and kidneys at a histological level. In addition, micronucleus and nuclear abnormalities tests were employed to examine damage to the genetic material. According to the frequency of Micronucleus, nuclear injuries, and the histopathology of gills and kidneys, it can be inferred that station S1 had the highest impact on the fish, causing significant harm. Based on our findings, the organisms residing in Lake Açu are adversely affected by the poor environmental conditions. This raises doubts about the effectiveness of the Protection Area by Humid Zone of International Interest in Northeast Brazil.

Cadmium and zinc accumulation and depuration in tilapia (Oreochromis niloticus) tissues following sub-lethal exposure.

Oreochromis niloticus was subjected to sub-lethal Cd and Zn concentrations for 14 days in order to evaluate their accumulation in the gills, liver, and muscle. Following that, the fish were placed to uncontaminated water for 7 days to allow the metals to be removed from the tissues. The gills had the highest bio-concentration factor for Cd and Zn. The gills showed the highest Cd accumulation rate, and the muscle showed the lowest. The muscle had the highest Cd depuration rate, while the liver had the lowest. The liver exhibited the highest Zn accumulation rate, while the gills and muscle had nearly similar values. Zn depuration rates were very consistent across all tissues.

Distribution of Tetrodotoxin in Pacific Oysters (Crassostrea gigas).

A potent and heat-stable tetrodotoxin (TTX) has been found to accumulate in various marine bivalve species, including Pacific oysters (Crassostrea gigas), raising a food safety concern. While several studies on geographical occurrence of TTX have been conducted, there is a lack of knowledge about the distribution of the toxin within and between bivalves. We, therefore, measured TTX in the whole flesh, mantle, gills, labial palps, digestive gland, adductor muscle and intravalvular fluid of C. gigas using liquid chromatography-tandem mass spectrometry. Weekly monitoring during summer months revealed the highest TTX concentrations in the digestive gland (up to 242 µg/kg), significantly higher than in other oyster tissues. Intra-population variability of TTX, measured in the whole flesh of each of twenty animals, reached 46% and 32% in the two separate batches, respectively. In addition, an inter-population study was conducted to compare TTX levels at four locations within the oyster production area. TTX concentrations in the whole flesh varied significantly between some of these locations, which was unexplained by the differences in weight of flesh. This is the first study examining TTX distribution in C. gigas and the first confirmation of the preferential accumulation of TTX in oyster digestive gland.

Characterization and spatial distribution of microplastics in two wild captured economic freshwater fish from north and west rivers of Guangdong province.

As a new type of pollutant, microplastics are of emerging widespread concern, while amount of research done in freshwater environments and organisms is litter compared to that in marine. Following this reality, the categories of MPs in two economic freshwater fish at 25 sites from 11 cities in the north and west rivers of Guangdong province were documented. Here, 76 individuals belong Oreochromis niloticus and Cirrhinus molitorella were investigated and microplastics were found in the GITs of 43.4% and gills of 25%. The average abundances of microplastics have significant difference between Oreochromis niloticus (0.015 items/ g) and Cirrhinus molitorella (0.031 items/g), while no difference by individual (~1.9 items). The plastics were dominated by white in color (61%), fragment in shape (67%), and lass than 1 mm in size (74%). The spatial distribution of microplastics revealed that there are significant differences between different cities in average abundances, and the highest average abundances of MPs were found in Zhanjiang city (4.25 items/individual) and Guangzhou city (0.044 items/g), respectively. Our results fully proved that the microplastics was widely ingested by wild fish species and suggested that the abundance and distribution of microplastics are positively related with the development of economy, tourism, industry, agriculture, and fishery.

Microplastics in Tissues (Brain, Gill, Muscle and Gastrointestinal) of Mullus barbatus and Alosa immaculata.

The researches on MPs in commercial marine fish are very limited although in marine environments microplastic (MPs) pollution is a global problem. In this study, the presence, composition, and characterization of MPs in different tissues (brain, gill, muscle, and gastrointestinal tract) of commercial fish species [red mullet (Mullus barbatus) and pontic shad (Alosa immaculata Bennett 1835)] from the Black Sea were investigated. M. barbatus (demersal) and A. immaculata (pelagic) fish were preferred in the selection of fish species in order to represent demersal and pelagic environments. After dissected the fish, MPs were obtained from the tissues by extraction using the flotation method; then the MPs were counted and categorized according to shape, size, and color. The composition of the MPs was determined via ATR-FTIR spectroscopy. In terms of microplastic abundance in fish tissues, the gastrointestinal tract (40.0%) ranked first in both fish species, while the lowest MPs density was determined in brain tissues (7.0%). After the gastrointestinal tissue, gills were identified as the second tissue with the highest MPs density. Regardless of fish species, MPs characterization was mainly fibrous (51.0%), black colored (49.0%), and 50-200 µm in size (55.0%). Among the nine different polymers determined, polychloroprene (18.8%) and polyamide (15.0%) were found most frequently. This research provides data for tissue-based assessment of MPs in fish. The obtained data showed that MPs (one of the anthropogenic pollutants) are quite high in all tissues regardless of fish species. Moreover, it has emerged that these two fish species are suitable for monitoring microplastics in the study area.

Physiological assessment of fish health in mineral-rich areas of Ganjam, Odisha, India, and chronic toxicity of zirconium oxychloride on the fishes of Channa punctata.

The high concentration of metal toxicants in aquatic ecosystems has a detrimental impact on fish health that ultimately jeopardizes human health. Such threats mostly arise in mineral-rich areas where an increase in metal concentrations occurs in aquatic bodies due to anthropogenic activities like mining. The present study assessed the health of food fish Channa punctata from the mineral-rich areas of Ganjam, Odisha, India, mined for heavy and transition metal ores like ilmenite, zircon, monazite. The fishes collected from these areas showed histopathological anomalies in vital organs like the liver, kidney, gills, stomach and intestine while cytological analysis revealed vacuolated cytoplasm and micronuclei. Biochemical analysis showed a significantly lower lipid concentration in muscle (i.e., 0.177 ± 0.177 mg/gm) and liver (i.e., 0.169 ± 0.002 mg/gm) as compared to non-exposed fishes from adjoining non-mineral rich areas having a mean protein concentration of 87.48 ± 8.16 and 77.75 ± 0.892 mg/gm tissue in the muscle and liver, respectively, and a mean lipid concentration of 0.29 ± 0.009 mg/gm muscle and 0.34 ± 0.009 mg/gm liver. Chronic exposure to sublethal concentrations of zirconium oxychloride, a salt of zirconium, resulted in a significant decline in the concentration of protein, ranging from 57.5 ± 0.929 - 63.88 ± 1.95 mg/gm in muscle and 45.35 ± 2.332 - 51.98 ± 1.036 mg/gm in the liver. The lipid concentrations in muscle (0.03 ± 0.009 - 0.17 ± 0.009 mg/gm) and liver (0.06 ± 0.012 - 0.19 ± 0.007 mg/gm) were also significantly lower than the non-exposed fishes. Marked degenerative changes were identified in the histological sections of the gill, intestine, stomach, liver and kidney of zirconium oxychloride-treated fishes along with various nuclear deformities and micronucleus.

Differential tissue accumulation in the invasive Manila clam, Ruditapes philippinarum, under two environmentally relevant lanthanum concentrations.

Among the environmental emerging concern rare earth elements, lanthanum (La) is one of the most common and reactive. Lanthanum is widely used in numerous modern technologies and applications, and its intense usage results in increasing discharges into the environment, with potentially deleterious consequences to earthlings. Therefore, we exposed the important food resource and powerful monitoring tool Manila clam to two environmentally relevant concentrations of La (0.3 µg L-1 and 0.9 µg L-1) for 6 days, through water, to assess the bioaccumulation pattern in the gills, digestive gland, and remaining body. The La bioaccumulation was measured after 1 (T1), 2 (T2), and 6 (T6) days of exposure. Lanthanum was bioaccumulated after 2 days, and the levels increased in all tissues in a dose-dependent manner. When exposed to 0.3 µg L-1, the enrichment factor pattern was gills > body > digestive gland. However, when exposed to 0.9 µg L-1, the pattern appears to change to gills > digestive gland > body. Tissue portioning appears to be linked with exposed concentration: In higher exposure levels, digestive gland seems to gain importance, probably associated with detoxification mechanisms. Here, we describe for the first time La bioaccumulation in these different tissues in a bivalve species. Future studies dealing with the bioaccumulation and availability of La should connect them with additional water parameters (such as temperature, pH, and major cations).

Temporal variation of biomarkers in common bream Abramis brama (L., 1758) exposed to untreated municipal wastewater in the Danube River in Belgrade, Serbia.

This study was conducted on the Danube River locality Visnjica, exposed to the discharge of the largest wastewater collector in Serbia's capital, Belgrade. Concentrations of metals and metalloids (Al, Fe, Cr, As, Sr, Mn, Cd, Zn, Mo, Cu, Li, Ni, B, Co, Pb, and Ba) and histopathological alterations were investigated in different tissues of common bream during one representative month of each season in 2014. This is the first study in which these two biomarkers were assessed parallelly in common bream. The highest concentrations of examined elements were noticed in gills and the lowest in muscle. Statistically significant differences in element concentrations between different seasons were noticed only in gills for Al, Cu, and Fe. Concentrations of As and Pb in fish muscle were below the maximum acceptable concentrations (MAC). The histopathological index (HI) of the liver showed higher values in comparison to the HI of the gills. Histopathological index of the gills had a significantly higher score in November in comparison to August. The liver HI had the highest score in April, and the lowest in August, while the total histopathological index had the highest score in November, and the lowest in August, both without significant differences between the months. This study endorses gills and liver as reliable organs for studying accumulation and histopathology as biomarkers of environmental changes. A faster reaction of the gills was confirmed since seasonal variations of both biomarkers were observed in this organ. Common bream proved as a good indicator of the state of organisms in polluted environments.

Biochemical and Histological Biomarkers in Crassostrea sp. (Bivalvia, Ostreidae) for Environmental Monitoring of a Neotropical Estuarine Area (São José Bay, Northeastern Brazil).

This study aimed to compare biochemical and histological biomarkers in oysters to identify impacted areas in a Brazilian port region. Oysters belonging to the Crassostrea genus were collected in two points in São José Bay (Brazil): (A1) Curupu Island (control area) and (A2) Braga Port (impacted area). Digestive glands from oysters were used to analyze the enzymatic activity of glutathione S-transferase and Catalase. The gills were used for standard histology analyses. Water samples were collected for metal analyses. Our results indicated that there was a change in the activity of oyster GST and CAT enzymes, especially in A2. Histological gill analysis indicated more frequent changes in A2. The analyzed metals presented higher values in A2. The results of this study suggest that enzymatic alterations, histological changes and higher metal values are indicative of initial stress caused by contaminants in São José Bay, especially in the port region.

Comparison of the Heavy Metals, Copper, Iron, Magnesium, Nickel, and Zinc Between Muscle and Gills of Four Benthic Fish Species from Shif Island (Iran).

Concentrations of copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) in muscle and gills of four Benthic fish species (Brachirus orientalis, Argyrops spinifer, Platycephalus indicus and Sillago sihama) from Shif Island of Iran were analyzed using flame atomic absorption spectrometry. The heavy metal levels observed in tissues varied for Cu: 2.15-820.98, Fe: 24.46-533.26, Mn: 1.80-53.17, Ni: 1.86-65.54 and Zn: 28.77-375.79 mg/kg. Significant differences were found among muscle and gill of the four fish species. Heavy metals concentration were significantly (p < 0.05) higher in the gill than in the muscles of all fish species studied. The metal levels in benthic fish species should be continuously monitored in polluted areas since benthic fish indicated a tendency to bioaccumulate pollutants in their tissues from polluted water. The indices of Estimated Daily Intake, Target Hazard Quotient and Hazard Index suggests no risk while carcinogenic risk for Ni showed unacceptable carcinogenic risk.

Genome-wide analysis of MicroRNA-messenger RNA interactome in ex-vivo gill filaments, Anguilla japonica.

BACKGROUND: Gills of euryhaline fishes possess great physiological and structural plasticity to adapt to large changes in external osmolality and to participate in ion uptake/excretion, which is essential for the re-establishment of fluid and electrolyte homeostasis. The osmoregulatory plasticity of gills provides an excellent model to study the role of microRNAs (miRs) in adaptive osmotic responses. The present study is to characterize an ex-vivo gill filament culture and using omics approach, to decipher the interaction between tonicity-responsive miRs and gene targets, in orchestrating the osmotic stress-induced responses. RESULTS: Ex-vivo gill filament culture was exposed to Leibovitz's L-15 medium (300 mOsmol l- 1) or the medium with an adjusted osmolality of 600 mOsmol l- 1 for 4, 8 and 24 h. Hypertonic responsive genes, including osmotic stress transcriptional factor, Na+/Cl--taurine transporter, Na+/H+ exchange regulatory cofactor, cystic fibrosis transmembrane regulator, inward rectifying K+ channel, Na+/K+-ATPase, and calcium-transporting ATPase were significantly upregulated, while the hypo-osmotic gene, V-type proton ATPase was downregulated. The data illustrated that the ex-vivo gill filament culture exhibited distinctive responses to hyperosmotic challenge. In the hyperosmotic treatment, four key factors (i.e. drosha RNase III endonuclease, exportin-5, dicer ribonuclease III and argonaute-2) involved in miR biogenesis were dysregulated (P < 0.05). Transcriptome and miR-sequencing of gill filament samples at 4 and 8 h were conducted and two downregulated miRs, miR-29b-3p and miR-200b-3p were identified. An inhibition of miR-29b-3p and miR-200b-3p in primary gill cell culture led to an upregulation of 100 and 93 gene transcripts, respectively. Commonly upregulated gene transcripts from the hyperosmotic experiments and miR-inhibition studies, were overlaid, in which two miR-29b-3p target-genes [Krueppel-like factor 4 (klf4), Homeobox protein Meis2] and one miR-200b-3p target-gene (slc17a5) were identified. Integrated miR-mRNA-omics analysis revealed the specific binding of miR-29b-3p on Klf4 and miR-200b-3p on slc17a5. The target-genes are known to regulate differentiation of gill ionocytes and cellular osmolality. CONCLUSIONS: In this study, we have characterized the hypo-osmoregulatory responses and unraveled the modulation of miR-biogenesis factors/the dysregulation of miRs, using ex-vivo gill filament culture. MicroRNA-messenger RNA interactome analysis of miR-29b-3p and miR-200b-3p revealed the gene targets are essential for osmotic stress responses.

Accumulation of trace elements in muscle, gill and liver of fish species (Capoeta umbla and Luciobarbus mystaceus) in the Tigris River (Turkey), and health risk assessment.

Two fish species (Capoeta umbla and Luciobarbus mystaceus) were collected from the Tigris River (Turkey), and tissues (gill, muscle and liver) of fish samples were analyzed for Cd, As, Mn, Cr, Cu, Co and Ni using the inductively coupled plasma-tandem mass spectrometry. Significant differences were present between fish species in regard to trace element (TE) concentrations in muscle for Mn, in liver for Cu, Cd and Mn, and in gill for As, Co, Cu and Cd (p < 0.05). Liver had the highest total TE concentration, followed by gill and muscle. Significant negative correlations were recorded between fish size (length and weight) and TE concentrations in the tissues. Both fish species showed no gender differences in TE accumulation in muscle, gill and liver (p > 0.05). The estimated daily intakes for all TEs were much lower than the tolerable daily intakes. The target hazard quotient (THQ) and total THQ values of all TEs did not exceed 1, which means that non-carcinogenic health effects are not expected for the consumers. Arsenic carcinogenic risk values were within acceptable range. Mean Cd concentrations in muscle tissue of both fish species exceeded the maximum permissible limit set by the European Commission Regulation, while mean concentrations of As, Cr and Cu were below the legislated limits.

Metal-Associated Biomarker Responses in Crabs from a Marine Protected Area in Southeastern Brazil.

The environmental quality of a Ramsar wetland site located at the Cananéia-Iguape-Peruíbe Protected Area (CIP-PA), in São Paulo, Brazil, was assessed by geochemical analyses and biomarker assessments (GPx, GST, GSH, GST, MT, LPO, DNA damage) performed in swimming crab Callinectes danae Smith, 1869 organs (posterior and anterior gills and hepatopancreas) to estimate sediment contaminant bioavailability. The results indicated that two sampling stations, PT and PM, exhibited the worst environmental conditions, as sediments collected at both points contained metal contamination, while crabs exhibited significant responses for GPx, GST, and LPO (mostly during winter). Sediment contamination tended to be associated to fine sediments (both seasons) and organic matter (winter). During the summer survey, Pb concentrations in sediments of station PT exceeded the Brazilian Sediment Quality Guidelines (SQGs) and the Canadian Interim Marine Sediment Quality Guidelines. Metal concentrations in sediments sampled in winter were higher compared with summer, with Co, Ni, and Pb exceeding SQGs levels at PT, whereas Co, Ni, Hg, Zn, and Pb exceeded SQGs at PM. Biomarker induction during summer appeared to be caused by natural variables (water salinity and temperature, and molting cycle), whereas oxidative stress and tissue damage during winter appeared to be more clearly linked to metal contamination. Anterior gills presented the clearest signs of seasonal variability, being more responsive to sediment contamination. The results suggest that metals originated from the upper Ribeira de Iguape River are transported toward the estuarine system, causing effects on C. danae individuals. Additionally, seasonality is a strong factor concerning CIP-PA toxicity, since the rainfall regime significantly modifies the freshwater flow and, consequently, estuarine water salinity, suspended particle and metal inputs, as well as the location of depositional areas. Thus, efforts to mitigate CIP-PA contamination should be based on the control of upstream pollution sources.

Nitric oxide levels in brain, liver, and gills of silver catfish (Rhamdia quelen) exposed to the antiparasitic eprinomectin.

Nitric oxide (NO) is a mediator and biomarker of pro- and anti-inflammatory processes. Excessive levels of NO for long periods have been associated with inflammation and tissue damage. The metabolism and synthesis of NO is usually measured indirectly, as metabolites and enzymes involved in reactions, often as the nitrite/nitrate (NOx) level. The aim of the present study was to measure the NOx levels in vital organs of juvenile silver catfish (Rhamdia quelen) exposed to various levels of eprinomectin in the water. The fish were exposed for 24 and 48 h to start concentration (0 h) of eprinomectin in water (0.0, 1.12, 1.80, and 3.97 µg/L). The eprinomectin concentrations in water were lower at 24 h (0.0, 0.85, 1.14, and 1.15 µg/L) and 48 h (0.0, 0.39, 0.69, and 1.28 µg/L), due to the process of eprinomectin metabolization. Subsequently, the fish were left for 48 h of recovery in eprinomectin-free water. NO levels were measured indirectly, as NOx levels in brain, liver, and gill tissue. Within 24 h of exposure, there was no significant increase in NOx levels in the organs evaluated at any of the concentrations tested. However, increases in NOx levels did occur at 48 h of exposure in all organs, particularly at the two highest concentrations of eprinomectin (1.80 and 3.97 µg/L). The transfer of fish to eprinomectin-free water did not result in reversal of NOx levels after 48 h of recovery, especially in fish that had been exposed to the two highest concentrations in the brain and liver tissues, and for the highest concentration in the gills. We conclude that silver catfish exposed to eprinomectin for up to 48 h present possible cerebral, hepatic, and branchial inflammatory process associated with increased tissue NOx levels, and that recovery for 48 h in water without antiparasitic is insufficient for the fish to recover from the poisoning.

Heavy Metals in Tissues of Blue Crabs Callinectes danae from a Subtropical Protected Estuary Influenced by Mining Residues.

This short note aims to report in detail a preliminary assessment of the concentrations of Cd, Hg and Pb in tissues of blue crabs Callinectes danae collected from the Cananéia-Iguape-Peruíbe estuarine complex (CIP), in the South of São Paulo State coast, Brazil. In October 2014, blue crabs were collected from CIP. Tissues were removed by dissection and metal determination was performed by GF-AAS and CV-AAS. According to statistical analysis, Pb and Cd concentrations in gills were significantly higher than those found in muscles and hepatopancreas, respectively. There were no significant differences in Hg concentrations between samples. Cd, Hg and Pb concentrations in gills and hepatopancreas were lower than those reported in a previous study performed at CIP. However, Cd concentration in hepatopancreas was higher than the Brazilian limit for consumption and new efforts to monitor Cd concentrations in C. danae tissues must be performed.

The Long-Term Exposure to Discharges of Sabal Drain Induces Genotoxic Effects on Oreochromis niloticus.

To study the genotoxic impacts of Sabal discharges, three sites around Sabal drain were selected and compared to a reference site (site1). Site2 was at the southern part of the main canal, site3 was at the main canal outlet, and site4 at the northern part of the main canal. Compared to the reference fish, the recorded micronuclei and other nuclear anomalies showed marked (p < 0.05) increases with different frequencies in the studied sites. The induction of nuclear deformations was as following site3 > site4 > site2 > site1. The analysis of comet assay data showed that the DNA damage (based on the percentage of tail DNA) was significantly increased and the levels of damage were associated with the distance from the main discharge point. Moreover, DNA damages showed variable percentages among the studied tissues. The gills and liver tissues collected from site3 showed the highest DNA damage compared with low muscular DNA damage.

Differential glycogen utilization in shark acid- and base-regulatory gill cells.

Na+/K+-ATPase (NKA)- and vacuolar H+-ATPase (VHA)-rich cells in shark gills secrete excess acid and base, respectively, to seawater to maintain blood acid-base homeostasis. Both cell types are rich in mitochondria, indicating high ATP demand; however, their metabolic fuel is unknown. Here, we report that NKA- and VHA-rich cells have large glycogen stores. Glycogen abundance in NKA-rich cells was lower in starved sharks compared with 24 h post-fed sharks, reflecting higher energy demand for acid secretion during normal activity and glycogen replenishment during the post-feeding period. Conversely, glycogen abundance in VHA-rich cells was high in starved sharks and it became depleted post-feeding. Furthermore, inactive cells with cytoplasmic VHA had large glycogen stores and active cells with basolateral VHA had depleted glycogen stores. These results indicate that glycogen is a main energy source in both NKA- and VHA-rich cells, and point to differential energy use associated with net acid and net base secretion, respectively.

The bioaccumulation of waterborne zinc in tissues of silver catfish (Rhamdia quelen) and its effect on biochemical parameters.

Silver catfish (Rhamdia quelen) is a fish species with neotropical distribution, and is a potential model organism to study polluted environment. The aim of this study is to analyze the response of silver catfish to environmental concentrations of waterborne zinc (Zn) over 96 h. Significant metal accumulation was seen in gill, intestine and liver tissues. No significant accumulation was seen in muscle tissue. Lipid peroxidation increased in the brain, and decreased in the muscle and liver at all levels of exposure. Zinc exposure led to decreased protein carbonyl levels in the brain and increased levels in the liver. The activity of catalase in the liver was reduced for all exposed groups. Glutathione S-transferase activity decreased in the brain at the highest level of exposure and in the liver at all Zn concentrations tested. Non-protein thiols increased in the muscle and in the gills after exposure. Ascorbic acid levels increased in the brain and in the gills. Exposure to Zn also altered the metabolic parameters, causing decreased lactate and ammonia levels in the muscle, and decreased glycogen in the liver. Zinc exposure increased ammonia and amino acid levels in the liver, and increase glycogen and amino acid levels in muscle tissue. Our results demonstrate that exposure to environmentally relevant concentrations of Zn led to accumulation of metals in the tissues of silver catfish, with significant changes in biochemical parameters.

Bacterial spoilage profiles in the gills of Pacific oysters (Crassostrea gigas) and Eastern oysters (C. virginica) during refrigerated storage.

Microorganisms harbored in oyster gills are potentially related to the spoilage and safety of oyster during storage. In this study, the microbial activities and pH changes of the gills of the two species, Crassostrea gigas and C. virginica, harvested from three different sites were determined and sensory evaluation was conducted during refrigerated storage. The bacteria in gills with an initial aerobic plate count (APC) of 3.1-4.5 log CFU/g rose remarkably to 7.8-8.8 log CFU/g after 8-days of storage. The APC of Enterobacteriaceae increased from 2.5 to 3.6 log CFU/g to 4.5-4.8 log CFU/g, and that of lactic acid bacteria (LAB) fluctuated in the range of 1.4-3.0 log CFU/g during the whole storage period. The results of sensory analysis indicated that the oysters had 8-days of shelf-life and that the gill presented the fastest deterioration rate. The pH of all samples showed a decrease in the early stages followed by an increased after 4-days of storage. The dynamic changes in microbial profiles were depicted to characterize gill spoilage by Illumina Miseq sequencing to characterize gill spoilage. The results revealed that oysters harvested at different sites showed common bacterial profiles containing Arcobacter, Spirochaeta, Pseudoalteromonas, Marinomonas, Fusobacterium, Psychrobacter, Psychromonas, and Oceanisphaera when spoiled, especially, among which Psychrobacter and Psychromonas (psychrotrophic genus) were represented as the most important gill spoiled bacteria during refrigerated storage, and Arcobacter with pathogenic potential was the dominated bacteria in all spoiled oysters. The consumption quality and safety of refrigerated oysters could be greatly improved by targeted control of bacteria in oyster gills according to the results the present study provided.

Changes in the gills of the European eel (Anguilla anguilla) after chronic exposure to environmental cocaine concentration.

The recent discovery of illicit drugs in the aquatic environment has raised concerns about the possible effects on the aquatic fauna, because of the pharmacological activity of these substances. Cocaine is an illicit drug widespread in surface waters since it is the third most widely used drug in North America, Western and Central Europe, and the second in Latin America and the Caribbean. The aim of this study was to evaluate the influence of environmental concentrations of cocaine on the gills of the European eel (Anguilla anguilla). The gills of male silver eels exposed to 20 ng L-1 of cocaine for fifty days were compared to control, vehicle control and post-exposure recovery ten days groups. The following parameters were evaluated: the thickness of the interlamellar epithelium (TIE), the length of the secondary lamellae (LSL) and the fraction of the interlamellar epithelium and the secondary lamellae occupied by the mucous cells (MC(IE-SL)FA) 3) the plasma cortisol and prolactin levels. After cocaine exposure, the gill epithelium appeared hyperplastic. The following changes were observed: proliferation in the interlamellar epithelium; partial and total fusion of the secondary lamellae, that appeared shortened and dilated; epithelial lifting and aneurism in the secondary lamellae. Moreover, in cocaine exposed eels, an increase in TIE and MC(IE-SL)FA and a decrease in LSL were observed. These changes were still present ten days after the interruption of cocaine exposure. Plasma levels of both cortisol and prolactin increased after cocaine exposure; ten days after the interruption of cocaine exposure, the plasma cortisol levels were still higher, whereas the plasma prolactin levels were lower, than control values. Our results show that even a chronic exposure to low environmental cocaine concentrations severely harms the eel gills, suggesting damages to their functions, and potentially affecting the survival of this species.