乌龙型灵芝发酵茶的Ames试验及其品质特征分析

对用乌龙茶制成的乌龙型灵芝发酵茶进行Ames试验,以进一步测定乌龙型灵芝发酵茶的食品安全性,并与乌龙茶生化成分、感官审评进行比较.结果表明,乌龙型灵芝发酵茶对TA97、TA98、TA100和TA1024株试验菌株无诱导致畸变作用.生化成分分析表明:乌龙型灵芝发酵茶的水浸出物、粗蛋白、咖啡碱、多糖、总氨基酸、必需氨基酸和支链氨基酸的含量比乌龙茶高13%、21%、16%、78%、110%、131%和157%;乌龙型灵芝发酵茶的茶多酚含量比乌龙茶低59%.感官评审表明,乌龙型灵芝发酵茶的品质特征明显优于乌龙茶.     

红曲中桔霉素的Ames试验

采用鼠伤寒沙门氏菌试验(Ames试验),通过观察0.2、1.0、5.0、25.0 μg/皿桔霉素处理对鼠伤寒沙门氏菌组氨酸缺陷型菌株TA97、TA98、TA100、TA102回复突变的影响,检测红曲中桔霉素的致突变性.结果表明,桔霉素受试物组回变菌落数均未超过自发回变菌落数的2倍,亦未呈现剂量反应关系,试验结果为阴性,红曲中桔霉素未表现出致突变性.     

应用Ames试验对氟化物诱发突变和抗突变活性的研究

应用Ames鼠伤寒沙门氏菌/微粒体酶技术研究了氟化钠(NaF)对TA98和TA100两个组氨酸缺陷型菌株的致突变和抗突变活性。结果表明,NaF对所试微生物缺乏致突变活性,且在中毒浓度下(>2000μg·皿-1)降低了试验菌株的回复突变频率;NaF对已知的阳性致突变物也未显示抗突变效应。     

饮用水消毒副产物的遗传毒性研究

介绍几种遗传毒理短期生物测试方法及其在饮用水中的应用,主要针对氯乙酸类和MX等饮用水消毒副产物(DBPs)的遗传毒性研究,研究结果表明,这些消毒副产物均有明显的诱变性。     

20种市售常见香辛料的抗氧化性对酱牛肉中杂环胺含量的影响

【目的】探讨市售常见香辛料的抗氧化性对酱牛肉中致癌、致突变性杂环胺种类和含量的影响。【方法】分别用福林-酚法和ABTS法测定20种香辛料的总酚含量和抗氧化能力,从中选出总酚含量较高、抗氧化能力较强的5种添加到酱牛肉的加工中,用HPLC法测定杂环胺含量。【结果】在只用蒸馏水煮的空白牛肉中检测出1-甲基-9H-吡啶并[3,4-b]吲哚(Harman)和9H-吡啶并[3,4-b]吲哚(Norharman) 两种杂环胺,而且含量很低;在用盐、白砂糖、酱油煮的对照牛肉中,除Harman和Norharman外还检测到了2-氨基-3,7,8-三甲基咪唑并[4,5-f]喹喔啉(7,8-DiMeIQx)、3-氨基-1-甲基-5H-吡啶并[4,3-b]吲哚(Trp-P-2)及3-氨基-1,4-二甲基-5H-吡啶并[3,4-b]吲哚(Trp-P-1) 3种杂环胺,5种杂环胺总含量为35.72 ng•g-1。所选取的丁香、桂皮、良姜、红花椒和香叶对杂环胺种类和含量的影响具有特异性：5种香辛料均能显著降低Harman和Norharman含量（P＜0.05）,对7,8-DiMeIQx、Trp-P-1及Trp-P-2 3种杂环胺影响各不相同。此外,香叶还能促进对照样品中未检测出的2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉(MeIQ)的形成。【结论】香辛料水提物对杂环胺的形成具有特异性影响。总体而言,良姜和红花椒能降低杂环胺总含量,在显著抑制7,8-DiMeIQx形成的同时不会产生新的杂环胺,因此抑制效果较好。     

Comparative genotoxicity testing of rhine river sediment extracts using the comet assay with permanent fish cell lines (rtg-2 and rtl-w1) and the ames test*

Goals, Scope and Background

Improved quality of surface waters and sediments requires advanced strategies for ecotoxicological assessment. Whilst at least in Germany assessment strategies on the basis of chemical analysis and acute toxicity data dominated the last decades, the development of more specific biological endpoints and biomarkers in ecotoxicology is required in order to arrive at a good ecological potential and good chemical status of surface waters in the European river basins until the year 2015, as required by the European Water Framework Directive. Since sediments have for long been known to function both as a sink and as a source of pollutants in aquatic systems, and since part of the particle-associated substances have frequently been demonstrated to cause mutagenic and carcinogenic effects in aquatic organisms, particularly in fish, there is, among other requirements, an urgent need to develop, standardize and implement integrated vertebrate-based test systems addressing genotoxicity into recent sediment investigation strategies. Thus, the present study was designed to compare the suitability of two commonly used test systems, the comet assay and the Ames test, for the evaluation of the ecotoxicological burden of surface and core sediment samples from the river Rhine.

Methods (or Main Features)

In order to determine the importance of inherent enzymatic activities, two permanent fish cell lines with different biotransformation capacities, RTL-W1 and RTG-2, were compared with respect to their capability of detecting genotoxic effects in 18 surface and core sediment samples from 9 locations along the River Rhine in the comet assay with and without exogenous bioactivation. For further comparison, as a prokaryotic mutagenicity assay, theSalmonella plate incorporation assay (Ames test) with the test strains TA98 and TA 100 with and without exogenous metabolic activation was used.

Results and Discussion

Whereas all sediment extracts induced genotoxic effects in the comet assay with RTL-W1 cells, only 12 out of 18 sediment extracts revealed significant genotoxicity in the tests with the less biotransformation-competent RTG-2 cells. Exogenous bioactivation by addition of ß-naphthoflavone /phenobarbital-induced S9 from rat liver resulted in both reduction or increase of genotoxicity in samples from different sites, however, without consistent reaction patterns. In general, the responses of RTL-W1 cells indicated higher biotransformation capacity than in RTG-2 cells without S9 complementation. In Ames tests using TA98 with S9, 16 out of 18 extracts induced significant mutagenicity with induction factors up to 4. Compared to TA98, the strain TA100 proved less sensitive, with maximum induction factors of 1.3, indicating the potential presence of substances inducing frarneshift mutations, which can only be detected in the strain TA98. Chemical analyses revealed particularly high levels of hexachlorbenzene (up to 860 µg/kg) and priority PAHs (up to 4.8 mg/kg); so far, however, no correlation could be found between compounds analyzed and the corresponding biotests.

Conclusions

Results document that both comet assay and Ames test are capable of detecting xenobiotic interaction with DNA in consequence of exposure to complex environmental samples. Whereas the alkaline version of the comet assay detects a broad range of interactions with the DNA, however without information about their eventual importance, the Ames test only reveals established mutations, but fails to detect transient (reparable) DNA alterations. However, even transient primary changes in the DNA structure might result in carcinogenic processes and, eventually, in implications at the population level. As a consequence, for hazard assessment purposes, a combination of both assays is required to avoid false negatives in genotoxicity evaluation. Poor correlation between data obtained by chemical analysis and results in bioassays is indicative of our limited understanding of the sources of genotoxicity. In fact, numerous studies combining chemical and biological approaches for hazard assessment of complex environmental mixtures indicate that priority pollutant concentrations are a poor indicator of toxicity.If compared to the cell line RTG-2, RTL-W1 proved more effective in detecting genotoxicity in surface sediment samples and, thus, indicated the importance of bioactivation of at least part of the compounds in superficial layers of sediments. Results further document that the common assumption may be wrong that, in comparison to deeper strata, surface layers carry a lower toxic burden in consequence of the current decrease in water pollution. This might at least in part be due to remobilization of more heavily polluted sediments from deeper layers during severe flood events followed by re-sedimentation in flood plains or upstream weirs, where they might cover less polluted younger sediment layers.

Recommendations and Perspectives

For a comprehensive assessment of genotoxicity in surface and core sediments, a combination of eukaryotic (comet assay) and prokaryotic assays (Ames test) with and without exogenous bioactivation is recommended. Since studies with organic sediments extracts simulate a worst-case scenario and fail to take into account bioavailability, there is broad consensus that whole-sediment exposure protocols represent the most realistic scenarios. Whereas more realistic solid phase exposure has frequently been applied in both microbial and invertebrate acute toxicity testing, there is an urgent need to develop corresponding whole sediment fish-based genotoxicity tests.

     

Temporal and spatial variations of net primary productivity and its response to groundwater of a typical oasis in the Tarim Basin,China

Net primary productivity (NPP) of the vegetation in an oasis can reflect the productivity capacity of a plant community under natural environmental conditions. Owing to the extreme arid climate conditions and scarce precipitation in the arid oasis regions, groundwater plays a key role in restricting the development of the vegetation. The Qira Oasis is located on the southern margin of the Taklimakan Desert (Tarim Basin, China) that is one of the most vulnerable regions regarding vegetation growth and water scarcity in the world. Based on remote sensing images of the Qira Oasis and daily meteorological data measured by the ground stations during the period 2006-2019, this study analyzed the temporal and spatial patterns of NPP in the oasis as well as its relation with the variation of groundwater depth using a modified Carnegie Ames Stanford Approach (CASA) model. At the spatial scale, NPP of the vegetation decreased from the interior of the Qira Oasis to the margin; at the temporal scale, NPP of the vegetation in the oasis fluctuated significantly (ranging from 29.80 to 50.07 g C/(m²•month)) but generally showed an increasing trend, with the average increase rate of 0.07 g C/(m²•month). The regions with decreasing NPP occupied 64% of the total area of the oasis. During the study period, NPP of both farmland and grassland showed an increasing trend, while that of forest showed a decreasing trend. The depth of groundwater was deep in the south of the oasis and shallow in the north, showing a gradual increasing trend from south to north. Groundwater, as one of the key factors in the surface change and evolution of the arid oasis, determines the succession direction of the vegetation in the Qira Oasis. With the increase of groundwater depth, grassland coverage and vegetation NPP decreased. During the period 2008-2015, with the recovery of groundwater level, NPP values of all types of vegetation with different coverages increased. This study will provide a scientific basis for the rational utilization and sustainable management of groundwater resources in the oasis.     

盘龙参内生真菌分布特征的研究

从盘龙参[Spiranthes sinensis(Pers)Ames]的根、茎、叶中共分离得到49株内生真菌,经形态观察,鉴定为3目、4科、9属。其中曲霉属、镰刀孢属、丝核菌属为优势种群,分别占已分离菌株数的16.3%、14.3%和14.3%。不同组织部位所分离得到的内生真菌在种群及数量上都存在差异:根中的优势属为镰刀孢属,占到了根中分离菌种数的23.5%;叶中的优势属是链格孢属,占到叶中分离菌种数的26.3%;茎中的优势属为长蠕孢属,占到叶中分离菌种数的23.1%。表明盘龙参内生真菌的分布具有一定的组织专一性。     

紫锥菊提取物的Ames试验

通过对紫锥菊提取物进行昆明种小鼠伤寒沙门氏菌回复突变试验,评价该材料的潜在致突变性。用紫锥菊提取物制备混悬液进行Ames（致突变）试验,采用平板掺入法,计数TA97、TA98、TA100、TA102标准测试菌株在4个不同浓度下,于37℃培养48h后的回复突变菌落数。结果显示无论在＋S9和-S9的情况下,各剂量组均未引起测试菌株回变菌落数的明显增加,Ames试验结果为阴性。说明紫锥菊提取物不引起鼠伤寒沙门氏菌的回复突变数增加,无致基因突变性。     

Mutagenicity,Creatine and Nutrient Contents of Pan Fried Meat from Various Animal Species

The mutagenic activity in extracts of fried meat from 16 different animal species was studied in Salmonella typhimurium TA98. In each experiment, 1 meat sample together with a standard beef sample was fried, and the mutagenicity was expressed relative to the beef sample. All meat samples showed less mutagenic activity than beef. The contents of creatine, creatinine, water, protein, carbohydrate and fat in the meat samples were analyzed, but mutagenicity was not correlated with the concentration of any of these constituents. Beef meat treated with creatinase to remove creatine produced reduced mutagenic activity. Possibly a threshold concentration of creatine is necessary to give a high mutagenic response.