Protective effect of Kappaphycus alvarezii (Rhodophyta) extract against DNA damage induced by mercury chloride in marine fish

Marine organisms are continuously exposed to agents, both exogenous and endogenous, that damage DNA. Consequently, it is important to determine the ability of compounds to provide protection against damaging chemicals. The aim of this study was to evaluate the anti-genotoxic activity of crude aqueous extracts of Kappaphycus alvarezii (Rhodophyceae), collected from the Southeast coast of India. This study focused on possible anti-genotoxic potential of aqueous extract of K. alverazii to interfere with clastogenicity induced by mercury chloride (HgCl₂) in marine fish, Therapon jarbua as measured by cytogenetic endpoints such as cell viability and comet assay. In the first set of experiments, fish were exposed to a single treatment of Hg at 0.125, 0.25, 0.5, 1, or 2?ppm along with controls. Mercury exposure produced significant DNA damage in all comet classes, maximum as >79% (Class 4) at 0.5, 1, and 2?ppm exposure in a time dependent manner. Algal extract did not induce genotoxicity when given alone and prevented Hg-induced genotoxicity. The algal extract reduction in genotoxicity was significant but not time- and concentration-dependent. Results suggested that under present experimental conditions, K. alvarezii extract exhibit potent anti-genotoxicity effects in this fish model; and thus these extracts may be recommended as a supplement in fish meal and may benefit humans ingesting Hg-contaminated fish.     

Cytotoxic and proinflammatory response of RAW 264.7 cells to differentially fractionated fungal fragments

Although significant research has been carried out for studying the impacts of pure mycotoxins on human cell, little information is known about the direct effects of fungal submicron particles. In this report, murine macrophage RAW 264.7 cells were exposed to fungal extracts from Stachybotrys chartarum RTI 5802 and Aspergillus versicolor RTI 3843 as well as mixtures from both fungi with fragment sizes ranging from 0.25 to 1?µm. Cell viability was found to be unaffected by all extracts except fragments in the 0.5–1?µm size range from A. versicolor RTI 3843, which decreased cell viability by approximately 60%. IL-1β expression was generally upregulated following exposure to fungal extracts from either S. chartarum RTI 5802 or A. versicolor RTI 3843. However, when extracts from the mixture of both fungi were introduced, IL-1β expression was downregulated. IL-6 and IL-10 expression were also generally upregulated. In comparison to the findings in the literature about the effects of pure mycotoxins on RAW 264.7 cells, the results presented herein show different patterns on mRNA expression which may be a result of the complex composition of the extract in terms of both mycotoxins and other fungal materials in addition to the potential interplay of the different components.     

In vitro assessment of natural plant extracts Withania somnifera,Cassia fistula,Saraca asoca,and Eucalyptus tereticornis using primary chicken embryo fibroblast cell culture treated with urea or mercuric chloride (II)

The present investigation examined the detoxifying potential of methanolic herbal extracts, namely the leaf and bark extract of Eucalyptus tereticornis, bark extract of Saraca asoca, Cassia fistula and Withania somnifera in vitro using primary chicken embryo fibroblast (CEF) cells against damaging effects of urea and mercuric chloride (HgCl) (II). The influence of 20?mM urea and 10?µM?HgCl (II) was determined on cell viability or proliferation of cells after treatment with plant extracts. Higher survival rate of primary CEF cells treated with higher concentrations of plant extracts was observed due to their protective ability against urea and HgCl (II). Cassia fistula bark extract (10?mg?mL^?1) was found to be most effective against 20?mM urea as it protects 90% of CEF cells whereas W. somnifera protects 86% of the cells within 24?h. After treating cells with10?µM HgCl, W. somnifera and E. tereticornis leaf extracts were found to be more effective among all other extracts as they protect approximately 86% and 70% of CEF cells, respectively, within 24?h. These results indicate that C. fistula and W. somnifera has the highest potential amongst all the five plant extracts for protecting CEF cells against damaging effects of urea and HgCl (II), respectively.     

氟虫双酰胺对蚯蚓的生化毒性与细胞毒性研究

双酰胺类杀虫剂已成为全世界第4大类最常用的杀虫剂,具有非常广阔的应用前景。然而,目前关于双酰胺类杀虫剂生态毒性评估方面的研究还比较少。为探究双酰胺类杀虫剂对非靶标生物的毒性作用,选取赤子爱胜蚓(Eisenia fetida)为受试生物,研究了典型双酰胺类杀虫剂氟虫双酰胺对非靶标动物蚯蚓的生化毒性和细胞毒性以及其在人工土和蚯蚓体内的浓度变化情况。结果表明,氟虫双酰胺在人工土壤中十分稳定,在整个暴露期间氟虫双酰胺的浓度变化不超过20%。氟虫双酰胺在蚯蚓体内的含量随染毒浓度的升高和暴露时间的推移而增加,呈明显的时间和剂量-效应关系;在染毒浓度为0.1和1.0 mg·kg-1的处理组中,氟虫双酰胺未对蚯蚓产生明显的氧化胁迫效应。在染毒浓度为5.0和10.0 mg·kg-1的处理组中,蚯蚓体内活性氧(ROS)含量显著高于其他处理组,过量的ROS诱导蚯蚓体内各种抗氧化酶活性发生异常变化,并在蚯蚓体内造成了脂质过氧化、蛋白质羰基化和DNA损伤。研究表明,当土壤中氟虫双酰胺的浓度为5.0和10.0 mg·kg-1时可能会对蚯蚓产生很高的风险。此外,彗星实验对氟虫双酰胺诱导的氧化胁迫较为敏感,可以作为敏感生物标志物对氟虫双酰胺造成的土壤污染进行预警。     

Assessment of DNA damage and cytotoxicity of palmatine on human skin epithelial carcinoma cells

The present investigation was carried out to examine the cytotoxic and genotoxic effects of a Tinospora cordifolia crude methanolic extract (palmatine) on human skin epithelial carcinoma cells (A431). T. cordifolia is one of the indispensable medicinal plants used in Ayurvedic medicine for treatment of various diseases and recommended for improving the immune system. Cytotoxicity and genotoxicity evaluation was carried out using A431 cells treated with different concentrations of palmatine. The duration of the treatment was 24 and 48 hr. A cellular proliferative capacity test showed that palmatine produced cytotoxicity in concentration- and time-dependent manner. Further, palmatine induced significant intracellular reactive oxygen species generation and elevated lipid peroxidation, as well as activities of catalase and superoxide dismutase. DNA fragmentation analysis using the comet assay showed that palmatine induced genotoxicity in a concentration- and time-dependent manner. Evidence indicates palmatine is capable of induction of oxidative stress resulting in cell death and genomic instability.     

几种抗生素对蛋白核小球藻的时间毒性微板分析法

抗生素在不同的暴露时间可能具有不同的毒性变化规律。本文以蛋白核小球藻(C.pyrenoidosa)为受试生物,96孔微板为暴露实验载体,5种抗生素硫酸安普霉素、氯霉素、双氢链霉素、硫酸新霉素和硫酸链霉素为研究对象,通过在C.pyrenoidosa生长周期内选取6个暴露时间节点(即0、12、24、48、72和96 h),建立了抗生素在不同暴露时间对C.pyrenoidosa生长抑制毒性的微板测试方法(简称T-MTA),并应用T-MTA方法系统测定了5种抗生素对C.pyrenoidosa在不同暴露时间的生长抑制毒性。结果表明,抗生素对C.pyrenoidosa生长抑制毒性具有明显的时间依赖特征,即在开始的时候基本无毒性,而后毒性迅速增加,然后毒性增加速度减慢;不同抗生素的毒性随着暴露时间的延长增加速率不同;同一暴露时间内,5种抗生素对C.pyrenoidosa的毒性大小不同;且毒性顺序随着暴露时间延长而发生变化。     

Polyphenol contents of five of medicinal plants from Cameroon and effects of their extracts on antioxidant capacities of human breast cancer cells

The aim of the study was to investigate the antiproliferative properties of extracts of five plants on breast cancer cells (MDA-MB-231) and their effects on antioxidant activities. The total phenol contents of the extracts were determined to establish a correlation to their antiproliferative effects which were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay. Enzymes involved in oxidative stress were also determined. Total polyphenol contents of the five extracts varied from 170 to 440 mg L^?1 of gallic acid per mg of extract with the highest value for the extract of Sida cordifolia. Cell growth inhibition was observed within 24 h, with inhibitory concentration values ranging from 7.3 to 25 mg L^?1 depending on plant extract. At concentrations between 100 and 200 mg L^?1, all the extracts exhibited significant reduction of cell proliferation in time-dependent and linear manner. The activities of superoxide dismutase and catalase of cells treated for 24 h with the extract of S. cordifolia were 3.5 U per mg protein and 8 mole H₂O₂ consumed per min per mg protein higher than those of cells treated with an extract of Viscum album.     

Microwave-assisted acid extraction of the major metal elements in herbal extracts followed by flame atomic absorption spectrometric (FAAS) determination

The content of As, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Pb, and Zn was determined in Rosa damascena, Vitis vinifera, Crocus sativus, and Olea europaea L. herbal extracts produced in different areas in Greece. Samples were mineralized in a closed microwave system using nitric acid, and the concentration of all metals was determined by flame atomic absorption spectrometry. The herbal extracts contained As, Cd, Cr, Hg, Mn, and Pb at concentrations below their respective limits of detection, whereas Cu, Fe, Mg, and Zn were determined in varying quantities. The proposed method is precise and accurate, thus it can be used for the determination of metals in Rosa damascena, Vitis vinifera, Crocus sativus, and Olea europaea L. herbal extracts.     

Callyspongia samarensis (Porifera) extracts exhibit anticancer activity and induce bleaching in Porites cylindrica (Scleractinia)

Marine sponges can produce allelopathic compounds with specific roles in the competition for benthic space. Here we demonstrate that extracts from Callyspongia samarensis (Phylum Porifera) accelerate bleaching in Porites cylindrica (Phylum Cnidaria, Order Scleractinia) and exhibit in vitro anticancer activity. A column chromatography fraction and HPLC fraction, purified from the crude methanol extract of C. samarensis, were incorporated into agar gel cubes at natural concentrations and tested on P. cylindrica corals in a laboratory assay. Statistical analysis of percent bleached area and maximum quantum yield showed that a significant difference existed between P. cylindrica nubbins that were exposed to C. samarensis extracts versus the control group. This suggests that C. samarensis contains allelopathic compounds that can cause bleaching in P. cylindrica, possibly leading to tissue necrosis and death. Furthermore, the aforementioned HPLC fraction exhibited significant growth inhibition of the HCT-116 (human colon cancer) cell line. Understanding the strategies by which sponges exert dominance over other organisms is important because it provides information about the ecological roles of sponge allelopathy and can result in the discovery of compounds with biomedical potential.     

Effects of ultraviolet radiation on different life cycle stages of the south Pacific kelps, Lessonia nigrescens and Lessonia trabeculata (Laminariales, Phaeophyceae)

The effects of exposure to ultraviolet radiation (UVR), 280–400 nm, in different life histories and development stages of the kelps, Lessonia nigrescens and L. trabeculata, collected in the south-east Pacific coast (30°S) were evaluated in the laboratory. Germination and viability (motile zoospores, settled spores), diameter of the primary cell of the gametophytes, percentage of female gametophytes, fertility and sporophytes production were measured after exposure to three radiation treatments (PAR; PAR + UVA; PAR + UVA + UVB). The effects of UVR in young sporophytes (diploid stage) were evaluated as changes in maximal quantum yield of chlorophyll fluorescence of photosystem II (PSII) (F _v/F _m). A significant decrease in all variables was observed for the treatment that included UVB (PAR + UVA + UVB) after 2 and 4 h of exposure, in relation to the control. The motile spores were more sensitive to UVR exposure compared to settled spores and gametophytes, suggesting that along with an increase in ontogenetic development; there is an increase in the tolerance to UVR. In addition, it was observed that early stages of the intertidal L. nigrescens were more tolerant to UVR compared to the subtidal L. trabeculata. These results allow initially to infer that UVR may be regarded as an important environmental factor influencing the upper limit of distribution of these species, mainly through its detrimental effects on the early stages of the life cycle.     

Sex pheromone of the tea aphid,Toxoptera aurantii (Boyer de Fonscolombe) (Hemiptera: Aphididae)

The tea aphid, Toxoptera aurantii, also called the “black citrus aphid”, is one of the most destructive insect pests in commercial tea plantations and gardens in southern China. In autumn, declining day length triggers production of winged T. aurantii sexuparae, which produce both winged males and wingless oviparae. Oviparous females then release sex pheromone that attracts potential mates. GC–MS analysis of volatile headspace extracts of T. aurantii oviparae revealed that they emit (4aS,7S,7aR)-nepetalactone (I) and (1R,4aS,7S,7aR)-nepetalactol (II) in a ratio of 4.3–4.9:1. Field-trapping experiments with synthetic I and II singly or as two-component blends of different doses and ratios showed significant attraction of T. aurantii males, as well as weak attraction of sexuparae. Identification of the T. aurantii sex pheromone provides a new opportunity for developing a pheromone-based monitoring and management strategy for the sexual phase of tea aphids and, possibly, the alate sexparous generation in late summer and fall.     

Gene expression profiling of human liver carcinoma (HepG2) cells exposed to the marine toxin okadaic acid

The marine toxin, okadaic acid (OA) is produced by dinoflagellates of the genera Prorocentrum and Dinophysis and is the causative agent of the syndrome known as diarrheic shellfish poisoning. In addition, OA acts as both a tumor promoter, attributed to OA-induced inhibition of protein phosphatases as well as an inducer of apoptosis. To better understand the potentially divergent toxicological profile of OA, the concentration-dependent cytotoxicity and alterations in gene expression on the human liver tumor cell line HepG2 upon OA exposure were determined using RNA microarrays, DNA fragmentation, and cell proliferation assays as well as determinations of cell detachment and cell death in different concentrations of OA. mRNA expression was quantified for approximately 15,000 genes. Cell attachment and proliferation were both negatively correlated with OA concentration. Detached cells displayed necrotic DNA signatures but apoptosis also was broadly observed. Data suggest that OA has a concentration dependent effect on cell cycle, which might explain the divergent effects that at low concentration OA stimulates genes involved in the cell cycle and at high concentrations it stimulates apoptosis.     

Aggregation pheromone compounds of the black larder beetle Dermestes haemorrhoidalis Kuster (Coleoptera: Dermestidae)

Gas chromatography with simultaneous flame ionisation and electroantennographic detection (GC–EAD) and gas chromatography with mass spectrometry analysis (GC–MS) of abdominal extracts of adult male Dermestes haemorrhoidalis Kuster (Coleoptera: Dermestidae) revealed the presence of electrophysiologically and behaviourally active compounds to its conspecific males and females. Isopropyl dodecanoate (3), isopropyl (Z)-9-tetradecenoate (5), isopropyl tetradecanoate (6), isopropyl (Z)-9-hexadecenoate (7) and isopropyl hexadecanoate (8) were detected in male abdominal extracts only. Analysis of collected male headspace volatiles revealed the presence of six EAD-active compounds (3), (5), (6) and isopropyl tridecanoate (4) plus two unidentified compounds (1) and (9). Synthetic compounds (3), (4), (5), (6) and (7) showed EAD activity with antennae of both sexes in contrast to synthetic (8) which showed EAD activity with female antennae only. Male and female antennae of D. haemorrhoidalis reacted with high receptor potentials to isopropyl (Z)-9-dodecenoate (2), although this compound itself was detected in neither male nor female abdominal extracts or headspace volatiles. Petri dish bioassays indicated that male abdominal extracts and compounds (2), (3), (5) and (6) aroused and attracted conspecific male and female beetles significantly (P < 0.05) compared to female extracts. These results suggested the presence of a male-produced aggregation pheromone in D. haemorrhoidalis. Field assays with any of the described compounds, however, did not result in attraction of this beetle in significant numbers.     

Relationship between cooling rates,cryoprotectant concentrations and salinities in the cryopreservation of marine microalgae

The viability of the marine microalgae Rhodomonas baltica Karsten, Isochrysis affinis galbana (Strain T-ISO) Parke, Chaetoceros gracilis Schütt, Tetraselmis chuii Butcher, Nannochloropsis gaditana Lubian and Nannochloris atomus Butcher, cryopreservec employing different cooling rates, either with or without the addition of the cryoprotective compounds dimethyl sulfoxide (DMSO) and methanol was studied at two exposure salinities. A viability index, which considered both cell recovery and the growth capacity of microalgae after thawing, was developed. The growth of thawed algae was compared to that obtained for unfrozen algae grown in liquid medium under the same conditions. Viability (V) was calculated according to the equation: V=(C ₀/C _i)x(C ₇/(a·C ₀ ^b ))x100, where C ₀ and C ₇ are, respectively, the initial and final cell densities measured in the cultures after thawing from-196°C, C _i is the maximum initial cell density (complete cell recovery), and a, b are the regression coefficients obtained for C ₇ as a function of C ₀ in the unfrozen controls. R. baltica was the only species that showed an improved viability when salinity was reduced from 36 (average viability 13.7% for 15% DMSO) to 20 (average viability 36.2% for 15% DMSO). The other five species displayed better viability only at the higher salinity at all tested cooling rates and cryoprotectant levels. T. chuii, Nannochloropsis gaditana, and Nannochloris atomus Butcher could be cryopreserved without cryoprotectant. However, their respective viabilities (32.7, 30.8 and 65.8%) at 36 S were progressively improved on addition of 5% DMSO (70.9, 48.2 and 93.5, respectively) and 15% DMSO (91.9, 57.0 and 94.2%, respectively). Similar improvements were found for Nannochloropsis gaditana and Nannochloris atomus when cryopreserved using methanol concentrations of 1% (average viabilities of 46.9 and 91.8, respectively) and 5% (average viablities of 48.7 and 95.3, respectively). Methanol was completely ineffective in cryopreserving the other four species and caused a lethal effect on T. chuii during freezing. C. gracilis could be cryopreserved with 5% DMSO only at 36 S. This resulted in a similar viability (11.7%) to that obtained using 15% DMSO in 20 S (13.7%). Keeping cryoprotectant concentration at 15% DMSO and raising salinity to 36 significantly improved the mean viability of C. gracilis to 21.6%. A low mean viability of 2.1% was obtained for I. galbana when 15% DMSO was used in full-strength seawater (36 S). Within the range of cooling rates tested (0.25 to 16 C° min^-1), cryopreserved microalgae showed higher viabilities at faster rates in the absence of cryoprotectants at both salinities. Generally, the dependence on cooling rate decreased proportionally to the concentration of DMSO or methanol, as demonstrated by the lack of significance for the slope of the regressions. Only C. gracilis appeared to depend on faster cooling rates in the presence of 15% DMSO.     

Assessment of lead (Pb) and cadmium (Cd) in 10 samples of Iranian and foreign consumed tea leaves and dissolved beverages

The tea bush (Comellia sinensis) is grown commercially in a large number of countries. Tea is a beverage, which consists of processed and dried tea leaves and is one of the most popular global drinks. Tea contains some heavy metals, such as Pb and Cd, which exert adverse effects on human health. The aim of this study was to determine the Pb and Cd levels in tea leaves and in the solution following dissolution in boiling water. In order to assess Pb and Cd in Iranian consumed tea, 10 tea samples were analyzed for metal concentration in tea leaves and boiled water solutions. For tea leaf analysis, the samples (5 g) were oven dried, ash dried in a cold oven, cooled at room temperature and then 2 mL nitric acid were added to the samples and the acid were evaporated on hot plate. For tea solution analysis, tea (5 g) was added to 250 mL of boiling distilled water and after filtering, the liquid was collected as tea solution. The results show that the average concentration of Pb and Cd in Iranian tea leaves was 9.73 and 0.67 mg kg^?1 and in foreign tea leaves 2.5 and 0.53 mg kg^?1, respectively. Shariat and Golkis representing Iranian, and Red Shahrzad and Ahmad representing foreign tea, showed the highest and lowest concentration respectively of Pb. Bamdad and Shariat representing Iranian, and Black Sedaghat and Ahmad representing foreign tea, showed the highest and lowest levels of Cd, respectively. The results showed that the longer the time of dissolution of the tea, the higher concentration of Pb and Cd in tea solution. In order to control Pb and Cd levels in tea, the type of water used in agriculture and quality of soil needs to be regulated.     

Mitochondrial dysfunction,impaired oxidative-reduction activity,degeneration, and death in human neuronal and fetal cells induced by low-level exposure to thimerosal and other metal compounds

Thimerosal (ethylmercurithiosalicylic acid), an ethylmercury (EtHg)-releasing compound (49.55% mercury (Hg)), was used in a range of medical products for more than 70 years. Of particular recent concern, routine administering of Thimerosal-containing biologics/childhood vaccines have become significant sources of Hg exposure for some fetuses/infants. This study was undertaken to investigate cellular damage among in vitro human neuronal (SH-SY-5Y neuroblastoma and 1321N1 astrocytoma) and fetal (nontransformed) model systems using cell vitality assays and microscope-based digital image capture techniques to assess potential damage induced by Thimerosal and other metal compounds (aluminum (Al) sulfate, lead (Pb)(II) acetate, methylmercury (MeHg) hydroxide, and mercury (Hg)(II) chloride) where the cation was reported to exert adverse effects on developing cells. Thimerosal-associated cellular damage was also evaluated for similarity to pathophysiological findings observed in patients diagnosed with autistic disorders (ADs). Thimerosal-induced cellular damage as evidenced by concentration- and time-dependent mitochondrial damage, reduced oxidative–reduction activity, cellular degeneration, and cell death in the in vitro human neuronal and fetal model systems studied. Thimerosal at low nanomolar (nM) concentrations induced significant cellular toxicity in human neuronal and fetal cells. Thimerosal-induced cytoxicity is similar to that observed in AD pathophysiologic studies. Thimerosal was found to be significantly more toxic than the other metal compounds examined. Future studies need to be conducted to evaluate additional mechanisms underlying Thimerosal-induced cellular damage and assess potential co-exposures to other compounds that may increase or decrease Thimerosal-mediated toxicity.     

Single walled carbon nanotubes induce cytotoxicity and oxidative stress in HEK293 cells

The aim of the present study was to evaluate the potential toxicity and general mechanisms involved in single walled carbon nanotubes (SWCNTs)-induced cytotoxicity using human embryonic kidney cell line (HEK293) cells. Carbon nanotubes (coded as CNT) used in this study were synthesized by the chemical vapor deposition method. To elucidate the possible mechanisms underlying SWCNT-induced cytotoxicity, cell viability, cell membrane damage (lactate dehydrogenase activity (LDH) assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation products levels were quantitatively assessed following SWCNT exposure for 48 hr using HEK293 cells. Exposure of cells to SWCNT at 3–300 μg/ml produced significant reduction in cell viability in a concentration-dependent manner. The IC₅₀ value of SWCNT was found to be 87.58 μg/ml. Exposure of HEK cells to SWCNT at 10–100 μg/ml resulted in concentration-dependent cell membrane damage, increased production of IL-8, elevated levels of thiobarbituric acid reactive substances like malondialdehyde and decreased intracellular GSH levels. In summary, exposure to SWCNT resulted in a concentration-dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.     

Antibacterial and antimutagenic activitiy of extracts and essential oil from (Tunisian) Pistacia lentiscus

Aqueous and flavonoid-enriched extract as well as essential oil (EO) obtained from leaves of Pistacia lentiscus were assessed for antibacterial and antimutagenic activities. Antibacterial activity of different extracts and EO were evaluated against six bacterial strains. A marked inhibitory effect was observed against Salmonella typhimurium, whereas lower activity was observed against Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. EO showed significant inhibitory effects against Salmonella typhimurium, Salmonella enteritidis and Staphylococcus aureus. The antimutagenic activity of the different extracts against Aflatoxin B₁ (AFB₁) and sodium azide was demonstrated with the Salmonella typhymurium assay. The number of revertants per plate decreased significantly when the plant extracts were added to the assay system using Salmonella typhimurium TA100, TA98 and TA1535.     

Lethal effects of Northwest Atlantic Ocean isolates of the dinoflagellate, Scrippsiella trochoidea, on Eastern oyster (Crassostrea virginica) and Northern quahog (Mercenaria mercenaria) larvae

The thecate dinoflagellate Scrippsiella trochoidea is a cosmopolitan, bloom-forming alga that has been generally considered non-toxic. Here, we report that environmentally relevant cell densities (10⁴ cells mL⁻¹) of Scrippsiella trochoidea strains isolated from the Northwest Atlantic Ocean caused 100% mortality in Eastern oyster (Crassostrea virginica) larvae during 3-day exposures while parallel control larvae exhibited 100% survival. S. trochoidea also exhibited lethal effects on Northern quahog (Mercenaria mercenaria) larvae (70% mortality during 3-day exposure) but were non-toxic to juvenile fish (Cyprinodon variegates). The cultures of S. trochoidea were more lethal to Northern quahog larvae than ten other species of harmful algae, including the highly toxic species Cochlodinium polykrikoides. Scrippsiella trochoidea cultures within later stages of growth were more toxic than exponential growth stages to bivalve larvae, and the toxicity was dose dependent. Furthermore, toxicity was maintained in the cultures that were sonicated, boiled, and frozen as well as in resuspended residues of the culture but was significantly lower in cell-free culture media. Collectively, these results suggest that S. trochoidea causes mortality in bivalve larvae through a physicochemical rather than strictly chemical mechanism, such as clogging of larval feeding apparatuses by materials produced by S. trochoidea (e.g., lipids, extracellular polysaccharides, and/or cell debris) which accumulate as cells in culture or blooms age. This is the first report of the lethal effects of Scrippsiella trochoidea on shellfish larvae.     

Evaluation of the antimutagenic and antiradical potentials of extracts from the tubers of (Tunisian) Cyperus rotundus

The mutagenic potential of aqueous, total oligomers flavonoids (TOF), ethyl acetate and methanol extracts from tubers of Cyperus rotundus L. was assessed using Ames Salmonella tester strains TA98 and TA100, and SOS chromotest strain Escherichia coli PQ37 with and without metabolic activation (S9). None of the different extracts produced a mutagenic effect. Likewise, the antimutagenicity of the same extracts was tested using the “Ames test” and the “SOS chromotest”. Our results showed that C. rotundus extracts possess antimutagenic effects against S. typhimurium TA98 and TA100 strains towards the mutagen aflatoxin B1 (AFB1), similar to E. coli PQ37 strain against AFB1 and Nifuroxazide mutagens using the SOS chromotest assay. A free radical scavenging test was used in order to explore the antioxidant capacity of the extracts obtained from the tubers of C. rotundus. TOF, ethyl acetate and methanol extracts showed an important free radical scavenging activity towards the 1,1-diphenyl-2-picrylhydrazine (DPPH) free radical. These extracts showed an IC50 value of respectively 5, 20 and 65?µg?mL^?1. The beneficial effects of TOF, ethyl acetate and methanol extracts of C. rotundus were assessed by antioxidant and antimutagenic activities.