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1.
Due to the widespread use of silver nanoparticles (AgNPs), the likelihood of them entering the environment has increased and they are known to be potentially toxic. Currently, there is little information on the dynamic changes of AgNPs in ecotoxicity exposure media and how this may affect toxicity. Here, the colloidal stability of three different sizes of citrate-stabilized AgNPs was assessed in standard strength OECD ISO exposure media, and in 2-fold (media2) and 10-fold (media10) dilutions by transmission electron microscopy (TEM) and atomic force microscopy (AFM) and these characteristics were related to their toxicity towards Daphnia magna. Aggregation in undiluted media (media1) was rapid, and after diluting the medium by a factor of 2 or 10, aggregation was reduced, with minimal aggregation over 24 h occurring in media10. Acute toxicity measurements were performed using 7 nm diameter particles in media1 and media10. In media10 the EC50 of the 7 nm particles for D. magna neonates was calculated to be 7.46 μg L−1 with upper and lower 95% confidence intervals of 6.84 μg L−1 and 8.13 μg L−1 respectively. For media1, an EC50 could not be calculated, the lowest observed adverse effect concentration (LOAEC) of 11.25 μg L−1 indicating a significant reduction in toxicity compared to that in media10. The data suggest the increased dispersion of nanoparticles leads to enhanced toxicity, emphasising the importance of appropriate media composition to fully assess nanoparticle toxicity in aquatic ecotoxicity tests.  相似文献   

2.
Although there is growing evidence that dietborne metals can be toxic to various aquatic species, there is still insufficient knowledge to integrate this information in environmental risk assessment procedures. In this study, we investigated the effects of a 21-day exposure of Daphnia magna to a control diet (i.e. the green alga Pseudokirchneriella subcapitata containing <4.0 μg Ni/g dry wt) and five diets with elevated Ni concentrations (i.e. the same alga contaminated with Ni burdens between 33.7 and 837 μg Ni/g dry wt). A significant accumulation of dietborne Ni in D. magna, i.e. between 49.6 and 72.5 μg Ni/g dry wt, was observed when they were fed with diets containing between 85.6 and 837 μg Ni/g dry wt. This was paralleled by a significant reduction of reproduction (by 33.1%), measured as the total number of juvenile offspring per female and growth (by 9.1%), measured as the carapax length of 21-day-old females. Life-history analysis showed that the time to first brood of Ni exposed organisms was between 7.8 and 8.2 days, and occurred 0.7–1.1 days earlier than for the control organisms (time to first brood = 8.9 days). The number of offspring in the first brood was significantly reduced (by 21–33% compared to the control) in all dietary treatments. Longer exposure (≥8.9 days, i.e. from the second brood onwards) led to a reduction of brood size only when given diets containing 85.6 and 837 μg Ni/g dry wt. The results suggest that a variety of mechanisms may be involved in the effects of dietary Ni exposure, including altered resource allocation or targeted reproductive inhibition. While Ni exposure clearly altered the quality of the diet (measured as essential ω3 polyunsaturated fatty acid content and C:P ratio), we found no conclusive evidence that these diet quality shifts could have affected growth or total reproductive output. More research is required to fully understand the mechanisms of Ni toxicity associated with the dietary exposure route.  相似文献   

3.
Cucumber and potato samples of known levels of pesticides and heavy metal residues, as respectively measured by gas chromatography and atomic absorption, were subjected to a bioassay method using Daphnia magna in order to assess the potential of the toxic hazard of their contaminants. Based on the estimated lethal time for 50% mortality (LT50) in daphnids, we suggested a classification to categorize toxic hazards in six definite ratings. Either samples of cucumbers (from conventional, greenhouse and organic farming) or potatoes (from conventional and organic farming) were evaluated for toxic hazard of the mixtures of pesticide residues and heavy metals, as well as mixtures of both. Accordingly, a 53.7% of cucumber samples were ranked as “Highly Toxic: HT”; a 18.5% “Moderately Toxic: MT); a 9.3% “Slightly Toxic: ST”; and a 18.5% “Practically Non-Toxic: NT”. For potato samples, the ranking pattern to different classes was: Extremely Toxic: ET (LT50 = <1 h) for 11.1%; Very Toxic: VT (LT50 = 1–<3 h) for 50.0%; HT (LT50 = 3–<12 h) for 13.9%; MT (LT50 = 12–<24 h) for 11.1%; ST (LT50 = 24–48 h) for 0.0%; and NT (LT50 = > 48 h) for 13.9% of the samples bioassayed.  相似文献   

4.
The zooplankton grazer Daphnia magna endures living in water bodies up to moderate densities of cyanobacteria, such as Microcystis spp., known for producing toxic secondary metabolites. Although daphnids are affected via decreased food filtering, inhibition of digestive proteases and lethality, development of tolerance against cyanobacterial toxins has also been observed. Aim of our study was to investigate in detail chronic effects of cyanobacterial toxins, with emphasis on microcystin, on D. magna. The animals were exposed chronically for two generations to either microcystin-LR in 5 or 50 μg L−1, or to cyanobacterial crude extract containing the same amount of total microcystin, starting at neonate stadium. Survival, growth, maturation and fecundity were observed for the first generation during two months. In the offspring survival, maturation, and growth were followed for the first week.Low concentration of microcystin-LR slightly affected the growth and reproduction of parent daphnids. Survivorship decreased during chronic exposure with increasing microcystin concentration. Age to maturity of the offspring increased and their survival decreased after parent generation was exposed to the toxin, even if the offspring were raised in control medium. Besides, cessation of the eggs/embryos was observed and malformation of neonates caused by cyanobacterial toxins was firstly recorded.  相似文献   

5.
Oils of Cymbopogon citratus, Ocimum gratissimum and Ocimum basilicum are widely used for their medicinal properties, and as food flavours and perfumes. Recently in a study in West Africa, these oils have been recommended to combat Fusarium verticillioides and subsequent fumonisin contamination in stored maize, but their toxicological profile was not investigated. The current study was undertaken to provide data on acute and subacute toxicity as well as on gastric tolerance of these oils in rat. For this purpose, the oils were given by gavage to Wistar rats for 14 consecutive days. The animals were observed daily for their general behaviour and survival, and their visceral organs such as stomach and liver were taken after sacrifice for histological analyses. A dose-dependent effect of the tested oils was observed during the study. Applied at doses generally higher than 1500 mg/kg body weight, the oils caused significant functional damages to stomach and liver of rat. Unlike the other oils, administration of O. gratissimum oil did not result in adverse effects in rat liver at the tested doses. The no observed adverse effect level (NOAEL) of the tested oils has been established. The three tested oils can be considered as safe to human when applied on stored maize at recommended concentrations.  相似文献   

6.
This study presents the results of a microsatellite and allozyme analysis on natural populations of the gudgeon (Gobio gobio) located in a pollution gradient of cadmium and zinc. Differences among contaminated and reference populations were observed at 2 allozyme loci, as well as a relationship between the fish condition factor and glucose-6-phosphate dehydrogenase genotypes, the locus that showed the largest difference in allele frequencies. The microsatellite data partly confirmed the differentiation pattern that was revealed by the allozyme survey. Our data further suggest that at least 2 microsatellite loci may be affected by natural selection. We thus illustrate that both microsatellite and allozyme loci do not necessarily behave as selectively neutral markers in polluted populations. Estimates of population differentiation can therefore be significantly different depending on which loci are being studied. Finally, these results are discussed in the light of the conservation unit concept, because microsatellites are often used to assess genetic variation in endangered natural populations and to propose measures for conservation or management.  相似文献   

7.
Cell content and composition of paralytic shellfish toxins of 10 cultured strains and 6 natural populations of Alexandrium tamarense from the Argentine sea, were analyzed. These data were compiled with previously published data into a comprehensive view of the toxin composition of the complex A. tamarense/Alexandrium catenella from southern South America.The N-sulfocarbamoyl derivatives C1,2 were predominant in almost all the cultured strains. The second major derivatives were GTX1,4, although the GTX1,4/C1,2 ratio varied largely. Some strains contain relatively high amounts of GTX2,3 (up to 29%) and/or neoSTX (up to 24%). In all strains STX was a minor component (0–4.4%) whereas GTX5 was present only in Alexandrium catenella isolates. Similarity analysis based upon toxin profiles showed that cultured strains from Argentine, Brazil, Chile and Uruguay clustered together. However, whereas some strains from the same geographic area exhibited different toxin profiles, and consistently fell out in separate subgroups, strains from Chile are grouped in a unique subgroup. In contrast to cultured strains, C1,2 were minor components among field populations. The highly toxic GTX1,4 were predominant in all spring field populations (69.1–93.6%). Moreover, their toxin cell content (163.9–261.4 fmol cell−1) and toxicity (68.2–93.0 pg STX equiv. cell−1) were several times higher that showed by the cultured strains. Field populations are more closely related to one another than to the cultured strains. However a less toxic and morphologically distinctive autumn population, contained GTX2,3 as the quasi unique (88.5%) toxin derivative clustered separately. Variability in toxin content and composition of A. tamarense field populations were well correlated with in situ temperature and nitrate concentration. Whereas toxin cell content and GTX1,4 (mol %) increased following saturation functions, GTX2,3 (mol %) decrease exponentially with the increase of the in situ nitrate concentration.  相似文献   

8.
9.
目的:比较冬虫夏草人工繁育品、野生品与亚香棒虫草中水解和游离氨基酸的含量。方法:采用氨基酸分析仪测定冬虫夏草人工繁育品、野生品以及亚香棒虫草中17种氨基酸的含量。结果:冬虫夏草人工繁育品的水解氨基酸含量为16.776%~19.080%,野生冬虫夏草为14.857%~21.959%,亚香棒虫草为13.043%~14.933%。冬虫夏草人工繁育品的游离氨基酸含量为1.767%~2.373%,野生冬虫夏草为1.753%~2.521%,亚香棒虫草为2.856%~3.197%。结论:冬虫夏草人工繁育品和野生品中氨基酸含量基本一致,和亚香棒虫草有显著性差异。本研究为冬虫夏草的鉴别及人工繁育品的进一步开发利用提供科学依据。  相似文献   

10.
Snake venom contains a complex protein mixture belonging to a few well-characterized protein families: disintegrins, phospholipase A2, serine protease, l-amino acid oxidase, Zn-dependent metalloproteinase, natriuretic peptides, myotoxins, cysteine-rich secretory protein (CRISP) toxins, Kunitz-type protease inhibitors and C-type lectin-like. Despite their pharmacological importance, little is known about the exact composition of each protein family. We report here the cloning of 25 complete ORFs from Macrovipera lebetina transmediterranea venom gland that encodes several isoforms and novel C-type lectins (CTLs). 16 alpha and nine beta CTL chains were identified. Based on their sequence alignment, we categorized the 16 CTL alpha subunits into five groups and the nine CTL beta subunits into four groups to deduce the phylogenetic tree of M. lebetina transmediterranea CTLs. Sequence analysis revealed that they share a high degree of similarity with each other and with other snake venom CTLs. The M. lebetina transmediterranea CTL sequences described here contain a C-lectin carbohydrate recognition domain-like fold (C-lectin CRD-like) characterized by several conserved amino acid residues in their structure, especially the cysteine. Finally, based on the comparison of some Macrovipera CTL, we propose that some new CTL gene versions should have occurred through “domains shuffling” from former genes.  相似文献   

11.
目的 以Nepasaikosaponin K为指标,建立柴胡属饮片中藏柴胡掺伪检测方法。方法 采用高效液相色谱-串联质谱技术(HPLC-MS/MS),电喷雾负离子多反应监测模式,以m/z 943.6→635.5、m/z 943.6→797.4、m/z 943.6→781.5为特征离子对,对北柴胡、南柴胡、锥叶柴胡、竹叶柴胡和藏柴胡等5种常见柴胡属饮片中Nepasaikosaponin K含量进行检测。进一步考察Nepasaikosaponin K定量离子对峰面积与藏柴胡掺伪比例之间线性关系,建立柴胡属饮片中藏柴胡掺伪比例计算公式,并以Nepasaikosaponin K为指标,开展藏柴胡掺伪限度研究。结果 Nepasaikosaponin K在藏柴胡中含量约为其他种柴胡的25~140倍。藏柴胡掺伪比例为0% ~ 100%范围内的混合样品中,定量离子对m/z 943.6→635.5峰面积与掺伪比例之间的线性关系良好。不同柴胡属掺伪模拟样品的计算掺伪量与实际掺伪量偏差在0.6%~1.4%之间。3批市售疑似掺伪北柴胡饮片中藏柴胡掺伪比例分别为14%、16%和27%。结论 该分析方法专属性强,灵敏度高,测定结果准确,为柴胡饮片中藏柴胡的掺伪情况筛查与评价提供依据,同时为其他中药饮片的掺伪情况分析提供新的思路与方法。  相似文献   

12.
Nepeta cataria L., commonly known as catnip, is a perennial herb with a considerable folkloric reputation. A diethyl ether extract of this plant has been shown to have antimicrobial activity against fungi and Gram-positive bacteria. The aim of this work was to study the activity of N. cataria extract on 44 Staphylococcus aureus strains, some resistant to methicillin, and S. aureus 6538P (American Type Culture Collection) by evaluating the effect of subminimum inhibitory concentrations on coagulase, DNAse, thermonuclease and lipase production, and on in-vitro adherence. DNAse, thermonuclease and lipase were inhibited by concentrations equal to 1/2 and 1/4 MIC. A reduction of adherence was also observed.  相似文献   

13.
The purpose of this study was to evaluate the in vitro antibacterial activity of a chitooligosaccharide mixture (MW 2000–30 000 Da) with a deacetylation degree of 91.5% against two representative oral pathogens, Actinobacillus actinomycetemcomitans and Streptococcus mutans. A 0.1% concentration of the chitooligosaccharides (derived from the exoskeletons of marine crustaceans) was used to estimate antibacterial activity. Approximately 2 log colony forming units (CFU)/ml of A. actinomycetemcomitans were inactivated by 0.1% chitosan after 30 min, while 120 min exposure inactivated about 4.5 log CFU/ml of this organism. In contrast, the level of inactivation against S. mutans was less than 0.5 log CFU/ml after an exposure of up to 120 min. Electron microscopy showed that the exposure of A. actinomycetemcomitans to the chitooligosaccharides resulted in the disruption of cell membranes and that it could be considered for the treatment of periodontal diseases associated with A. actinomycetemcomitans.  相似文献   

14.
目的 建立HPLC测定梅花鹿鹿茸和马鹿鹿茸药材中尿嘧啶、次黄嘌呤、尿苷、鸟苷和肌苷5种核苷成分含量的方法,并比较不同批次的梅花鹿鹿茸和马鹿鹿茸药材中5种核苷类成分含量的差异。方法 采用HPLC对15批梅花鹿鹿茸药材和15批马鹿鹿茸药材进行测定,并对测定结果进行聚类分析。结果 测定了梅花鹿鹿茸和马鹿鹿茸药材中5种核苷类成分的含量,二者中核苷类成分含量差异显著;不同产地不同养殖户的鹿茸药材中,5种核苷成分含量也存在明显差异。采用聚类分析能将不同产地的15批梅花鹿鹿茸和15批马鹿鹿茸药材分为2类。结论 不同产地梅花鹿鹿茸和马鹿鹿茸药材核苷成分的组成存在显著性差异,鹿茸药材的质量受鹿的品种、自然环境、养殖技术等因素的影响。该方法适用于梅花鹿鹿茸和马鹿鹿茸中核苷类成分的含量测定,为二者质量控制提供保证。  相似文献   

15.
目的 研究甘草和大戟配伍的体外肝毒性。方法 采用显微观察法和MTT法检测不同浓度的甘草单煎液、大戟单煎液、甘草-大戟合煎液和甘草-大戟单煎混合液对人肝癌细胞HepG2增殖的影响,并比较大戟单煎液、甘草-大戟合煎液和甘草-大戟单煎混合液相当浓度下细胞毒性的大小。结果 大戟单用及大戟与甘草配伍均有细胞毒性,且呈剂量相关性;与大戟单煎液相比,甘草-大戟单煎混合液细胞毒性无明显差异,甘草-大戟合煎液细胞毒性减小。结论 甘草和大戟配伍导致大戟的体外肝毒性减小。  相似文献   

16.
Andrographis paniculata (Family: Acanthaceae) and Swertia chirayita (Family: Gentianaceae) are two controversial medicinal plants used as Kiriyattu, having similar therapeutic action and are used as a hepatoprotective and hepatostimulative agent. A. paniculata grows in southern parts of India and S. chirayita in the Himalayan region. The present work concerns on the ability of the extracts of these plants to offer protection against acute hepatotoxicity induced by paracetamol (150 mg/kg) in Swiss albino mice. Oral administration of A. paniculata or S. chirayita extract (100–200 mg/kg) offered a significant dose dependent protection against paracetamol induced hepatotoxicity as assessed in terms of biochemical and histopathological parameters. The paracetamol induced elevated levels of serum marker enzymes such as serum glutamate pyruvate transaminase (GPT), serum glutamate oxaloacetate transaminase (GOT), alkaline phosphatase (ALP), and bilirubin in peripheral blood serum and distorted hepatic tissue architecture along with increased levels of lipid peroxides (LPO) and reduction of superoxide dismutase (SOD), catalase, reduced glutathione (GSH) and glutathione peroxidase (GPx) in liver tissue. Administration of the plant extracts after paracetamol insult restored the levels of these parameters to control (untreated) levels. Thus the present study revealed that the extracts of A. paniculata or S. chirayita offered protection against hepatotoxicity induced by paracetamol.  相似文献   

17.
目的 探讨VKORC1-3673G>ACYP2C9*3CYP4F2 rs2108622CYP2C19*2位点基因多态性对中国汉族房颤患者华法林维持剂量的影响。方法 收集107例服用华法林达维持剂量的汉族房颤患者的血样和临床相关资料,应用PCR-RFLP法检测VKORC1-3673G>ACYP2C9*3CYP4F2 rs2108622CYP2C19*2基因型,采用独立样本t检验分析基因型与华法林维持剂量的相关性。多元线性回归建立给药模型,探讨基因多态性对华法林维持剂量的影响。结果 VKORC1-3673G>ACYP2C9*3CYP4F2 rs2108622基因多态性和患者年龄、体质量能解释45.2%的华法林维持剂量差异。CYP2C19*2基因多态性对本研究人群华法林维持剂量无影响。结论 VKORC1-3673G>ACYP2C9*3CYP4F2 rs2108622基因多态性显著影响中国汉族房颤患者的华法林维持剂量。  相似文献   

18.
蝙蝠蛾拟青霉与冬虫夏草关系的分子系统学研究   总被引:2,自引:0,他引:2  
以5月和6月两个不同时段采集的分别产于青海省化隆县和四川省康定县的冬虫夏草(Cordyceps sinensis)新鲜子实体为材料,采用分子生物学方法,以rDNA-ITS序列为分子标记,对蝙蝠蛾拟青霉(Paecilomyces hepiali)与冬虫夏草之间的关系进行了探讨。以真菌通用引物ITS1/ITS4分别对蝙蝠蛾拟青霉及冬虫夏草子座和僵虫基因组DNA进行PCR扩增,获得的片段克隆到pMD18-T Vector上进行测序,结果表明,随机挑取的46个克隆与某些已在GenBank中注册的中国被毛孢(Hirsutella sinensis) 或冬虫夏草的rDNA-ITS序列的一致性均在99%以上,但与蝙蝠蛾拟青霉的rDNA-ITS序列的一致性约为72%。根据蝙蝠蛾拟青霉的rDNA-ITS序列设计了两对特异引物,分别以不同产地及不同生长时期共4个批次的冬虫夏草子座和僵虫基因组DNA为模板,进行PCR及巢式PCR扩增,均得到了相应片段,该片段与蝙蝠蛾拟青霉的rDNA-ITS序列具有100%的一致性。在GenBank中注册号为AB067740的另一个标明为冬虫夏草的rDNA-ITS序列与注册号为AJ309353的中国被毛孢的rDNA-ITS序列一致性仅为87.3%,但根据AB067740序列设计特异引物,也从冬虫夏草基因组DNA中扩增到其相应序列。研究结果表明,在天然冬虫夏草中除了中国被毛孢之外,还普遍存在着蝙蝠蛾拟青霉等内寄生菌。  相似文献   

19.
Seventeen Great Lakes sediments ranging in degree of expected toxicity were evaluated using a 21 day sediment elutriate bioassay with Daphnia magna. Sediments differed in their effects on survival, age at first reproduction, the number of broods produced and the total number of young produced per adult. Sediments producing low survivorship (50–60%) also had negative effects on reproduction. However, both positive and negative effects on reproduction were found among sediments producing high survivorship. To integrate all test end-points, a stochastic matrix population model was constructed and parameterized with survival and reproduction data from each sediment. By including estimates of variability in vital rates, the model output provided quantitative estimates of uncertainty in projected population size. Sediment effects on survival and reproduction translated into large differences in projected population growth; mean estimates of projected population size at day 28 of the simulations ranged over two orders of magnitude among the 17 sediments. Reproductive timing (e.g. age at first reproduction), followed by fecundity and survivorship, had the largest effect on population growth. Results of this study also indicate that the presence of suspended sediment in elutriates may confound toxicity evaluations using cladocerans. The concentration of total suspended solids was negatively correlated with age at first reproduction and positively correlated with measures of fecundity and population growth. In order to realize the potential benefits of chronic testing we must develop ecologically relevant ways of interpreting sediment bioassay results and expressing the uncertainty associated with our estimates of ecological risk.  相似文献   

20.
目的 对滇南金线兰进行生药鉴定,明确其原植物形态和显微特征。方法 采用生药学鉴定方法,观察滇南金线兰的原植物形态、组织构造及粉末显微特征。结果 叶片呈卵形或卵状披针形,具金红色叶脉,花不倒置,唇瓣黄色,呈Y字形,前部明显扩大并2裂,裂片狭长圆形或狭倒披针形,中部收狭成长10 mm左右、其边缘具狭翅。显微结构中,根、茎横切面中皮层明显,具草酸钙针晶、黏液细胞等;叶横切面上表皮细胞乳突状,下表皮气孔类型多样,以不定式气孔为主。粉末中可见草酸钙针晶和导管。结论 滇南金线兰的生药鉴定为其资源开发利用提供了参考依据。  相似文献   

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