雨生红球藻fachb-712快速繁殖生长的适宜条件

目的 探讨雨生红球藻fachb-712快速繁殖生长的适宜条件.方法 利用分光光度法和显微镜计数法绘制光密度与细胞密度的关系曲线,从不同的pH值、光照强度、接种密度、温度等培养条件入手,对影响雨生红球藻生长的各种主要培养条件进行初步研究.结果 雨生红球藻生长的适宜培养条件为:pH 8.0;光照强度1 klx下连续培养24h;温度24 ℃;接种量1.95×105mL-1.结论 雨生红球藻细胞密度与培养物光密度值满足线性关系,pH 8.0、光照强度1 klx下连续培养24h、温度24 ℃、接种量1.95×105mL-1的培养条件适宜雨生红球藻快速繁殖生长.     

红外光谱-人工神经元网络法测定海藻培养过程中的碳酸盐浓度

用傅里叶变换红外光谱法测定海藻培养液中碳酸盐浓度时，由于pH对碳酸盐特征吸收峰影响严重，本文用人工神经元网络处理红外光谱，用该方法计算得到：对标准样品的预测标准误差为NaHCO3 0．08g／L，pH值为0．12，优于偏最小二乘法的结果。用该方法对实际螺旋藻培养过程中的碳源浓度进行了测定，预测标准误差为0．65g／L。     

Ecotoxicity and uptake of polymer coated gold nanoparticles

Abstract

Bioconjugated gold nanoparticles (Au NPs) are a promising tool for pharmaceutical applications. However, the ecotoxicity of these types of NPs has hardly been studied. We investigated the ecotoxicity and uptake of 4–5 nm Au NPs to which two types of polymer coatings were attached. One coating was an amphiphilic polymer only and the other an amphiphilic coating to which 10 kDa polyethylene glycol chains were attached. In both 72 h algal growth inhibition tests with the alga Pseudokirchneriella subcapitata and in 24 h resazurin cytotoxicity tests with the rainbow trout gill cell line RTGill-W1, the pegylated Au NPs were found less toxic compared to the amphiphilic coated particles. No uptake or direct interaction between particles and algal cells was observed. However, uptake/adsorption in fish gill cells reached up to >10⁶ particles/cell after 1 h and particles were eliminated for ≥96% after 24 h depuration. Both particle types were found within membrane enclosed vesicles in the cytoplasm of RTgill-W1 cells.     

Induction of reactive oxygen species in chlamydomonas reinhardtii in response to contrasting trace metal exposures

The toxicity of metals to organisms is, in‐part, related to the formation of reactive oxygen species (ROS) in cells and subsequent oxidative stress. ROS are by‐products of normal respiration and photosynthesis processes in organisms, but environmental factors, like metal exposure, can stimulate excess production. Metals involved in several different mechanisms such as Haber‐Weiss cycling and Fenton‐type reactions can produce ROS. Some metals, such as Cd, may contribute to oxidative stress indirectly by depleting cellular antioxidants. We investigated the measurement of ROS as a sensitive biomarker of metal toxicity (that could possibly be implemented in a biotic ligand model for algae) and we compared ROS induction in response to several contrasting transition metals (Cu, V, Ni, Zn, and Cd). We also compared the ROS response to glutathione and growth toxicity endpoints measured in a previous study. The cell‐permeable dye, 2′7′dichlorodihydrofluorescein diacetate, was used as a probe to detect formation of ROS in Chlamydomonas reinhardtii cells. Metal‐exposed cells were incubated with the fluorescent dye in a 96‐well plate and monitored over 5.5 h. A dose‐response of ROS formation was observed with Cu exposure in the range of 20–500 nM. Cu produced more ROS compared with either Zn or Cd (both nonredox active metals). The redox‐active metal V produced increased ROS with increased concentration. The measurement of ROS may be a useful indicator of Cu toxicity, but the signal to noise ratio was better for the glutathione endpoint assay. © 2011 Wiley Periodicals, Inc. Environ Toxicol 28: 516–523, 2013.     

Ecotoxicity and screening level ecotoxicological risk assessment of five antimicrobial agents: triclosan,triclocarban, resorcinol,phenoxyethanol and p‐thymol

Acute and chronic (or sub‐chronic) toxicity of five selected antimicrobial agents, including triclosan (TCS), triclocarban (TCC), resorcinol, phenoxyethanol and p‐thymol, was investigated using the conventional three‐aquatic‐organism battery. These compounds are widely used in cosmetics and other personal care products and their ecological risk has recently become a significant concern. As results of toxicity tests, TCS was found to be most strongly toxic for green algae [e.g. 72 h no observed effect concentration (NOEC) of 0.50 µg l^?1] among the selected compounds, followed by TCC, while TCC was more toxic or similar to TCS for Daphnia and fish (e.g. Daphnia 8 day NOEC of 1.9 µg l^?1). Having compared the predicted no effect concentration (PNEC) determined from the toxicity data with measured environmental concentrations (MEC), the preliminary ecological risk assessment of these five antimicrobials was conducted. The MEC/PNEC ratios of TCS and TCC were over 1 for some monitoring data, especially in urban streams with watershed areas without sewage service coverage, and their potential risk for green algae and Daphnia might be at a level of concern, although the contribution of TCS/TCC on the total toxicity of the those sites needs to be further investigated. For the three other antimicrobials, the maximum MEC/PNEC ratio for resorcinol was 0.1–1, but those for phenoxyethanol and p‐thymol were <0.1 and their risk to aquatic organisms is limited, although the additive effects with TCS, TCC and other antimicrobial agents, such as parabens, need to be further examined in future studies. Copyright © 2012 John Wiley & Sons, Ltd.     

Preliminary isolation and in vitro antiyeast activity of active fraction from crude extract of Gracilaria changii

Objective:

To isolate the active fraction from crude extract of Gracilaria changii and to determine its in vitro antifungal activity.

Materials and Methods:

The active fraction was isolated from the crude extract of G. changii by various purification procedures such as column chromatography, thin layer chromatography, bioauthograph etc. The in vitro antifungal activity (Candida albicans) of the active fraction (1.00, 0.50, and 0.25 mg/ml) was studied by disc diffusion method and the effect of the active fraction on the morphology of yeast was done by scanning electron microscope (SEM) studies.

Results:

An active fraction with remarkable antifungal activity was separated from the crude extract. The active fraction was effective as a fungicide against C. albicans and showed a dose-dependent antifungal activity. A Scanning Electron Microscope (SEM) study confirmed the fungicidal effect of G. changii active fraction on C. albicans, by changing the normal morphology of C. albicans.

Conclusion:

From G. changii crude extract, an active fraction with remarkable in vitro antifungal activity has been isolated.     

Continental diatom biodiversity in stream benthos declines as more nutrients become limiting

Biodiversity of both terrestrial ecosystems and lacustrine phytoplankton increases with niche dimensionality, which can be determined by the number of limiting resources (NLR) in the environment. In the present continental study, I tested whether niche dimensionality and, with this species, richness scale positively with NLR in running waters. Diatom richness in 2,426 benthic and 383 planktonic communities from 760 and 127 distinct localities, respectively, was examined as a function of NLR, including basic cations, silica, iron, ammonia, nitrate, and dissolved phosphorus. The patterns found in the two communities were opposite: as more resources became limiting, diatom richness declined in the benthos but increased in the phytoplankton. The divergence of benthic from both planktonic and terrestrial communities is attributed to the complex spatial organization of the benthos, generating strong internal resource gradients. Differential stress tolerance among benthic diatoms allows substantial overgrowth, which greatly reduces nutrient transport to the biofilm base and can be supported only by high ambient resource levels. Therefore, niche dimensionality in the benthos increases with the number of resources at high supply. These findings provide a mechanistic explanation of the well documented phenomenon of increased species richness after fertilization in freshwater as opposed to terrestrial ecosystems. Clearly, however, new theoretical approaches, retaining resource availability as an environmental constraint but incorporating a trade-off between tolerance and spatial positioning, are necessary to address coexistence in one of the major producer communities in streams, the algae.     

Evaluation of antigenotoxic effects of carotenoids from green algae Chlorococcum humicola using human lymphocytes

Objective

To identify the available phytochemicals and carotenoids in the selected green algae and evaluate the potential genotoxic/antigenotoxic effect using lymphocytes.

Methods

Organic solvent extracts of Chlorococcum humicola (C. humicola) were used for the phytochemical analysis. The available carotenoids were assessed by HPLC, and LC-MS analysis. The genotoxicity was induced by the benzo(a)pyrene in the lymphocyte culture, the genotoxic and antigenotoxic effects of algal carotenoids with and without genotoxic inducer were evaluated by chromosomal aberration (CA), sister chromatid exchange (SCE) and micronucleus assay (MN).

Results

The results of the analysis showed that the algae were rich in carotenoids and fatty acids. In the total carotenoids lutein, β-carotene and α-carotene were found to be present in higher concentration. The frequency of CA and SCE increased by benzo(a)pyrene were significantly decreased by the carotenoids (P<0.05 for CA, P<0.001 for SCE). The MN frequencies of the cells were significantly decreased by the treatment with carotenoids when compared with the positive controls (P<0.05).

Conclusions

The findings of the present study demonstrate that, the green algae C. humicola is a rich source of bioactive compounds especially carotenoids which effectively fight against environmental genotoxic agents, the carotenoids itself is not a genotoxic substance and should be further considered for its beneficial effects.