Effect of endocrine disrupters on photosystem II energy fluxes of green algae and cyanobacteria

Among the numerous toxics found in the aquatic environment, endocrine disrupters can interfere with the normal functioning of the endocrine system of several organisms, leading to important consequences. Even if algae and cyanobacteria are non-target organisms without endocrine system, our goals were to verify if endocrine disrupters can affect photosynthetic activity and how energy flows through photosystem II (PSII) were altered. To reach these objectives, we exposed, for 15 min, two green algae (Chlamydomonas reinhardtii strain CC125, Pseudokirchneriella subcapitata strain CPCC37) and a toxic and a non-toxic strain of Microcystis aeruginosa (CPCC299 and CPCC632 respectively) to 4-octylphenol, 4-nonylphenol and β-estradiol at concentrations ranging from 0.1 to 5 μg/mL. We have shown for the first time that endocrine disrupters may have drastic effects on PSII energy fluxes. Furthermore, we showed that various species have different sensitivity to endocrine disrupters. P. subcapitata was tolerant to each endocrine disrupter tested, while flows of energy through PSII were affected similarly, but at different extent, for the other species. Cyanobacterial PSII energy fluxes were more affected than green algae, suggesting that the prokaryotic characteristics of these organisms are responsible of their high sensitivity.     

Antimicrobial Activities of Volatile Components and Various Extracts of Dictyopteris membranaceae. and Cystoseira barbata. from the Coast of Izmir,Turkey

Abstract

The methanol, dichloromethane, hexane, chloroform, and volatile components of Dictyopteris membranaceae. (Stackhouse) Batters (Dictyotaceae) and Cystoseira barbata. (Good et Woodw.) J. Agardh (Cystoseiraceae) were tested for their antimicrobial activities (four Gram-positive bacteria, four Gram-negative bacteria, and Candida albicans. ATCC 10239). Five compounds were identified in the volatile oil of D. membranaceae. accounting for >85% of the composition of the volatile oil. Twenty-eight compounds were identified in the volatile oil of C. barbata. accounting for >67% of the composition of the volatile oil. Major components were 6-butyl-1,4-cycloheptadiene (43.21%) for D. membranaceae. and docosane (7.61%) and tetratriacontane (7.47%) for C. barbata.. Many compounds in the volatile oil of C. barbata. were identified as hydrocarbon compounds. The volatile oils of these algae did not remarkably inhibit the growth of tested microorganisms. However, the hexane extracts showed more potent antimicrobial activity than methanol, dichloromethane, and chloroform extracts.     

Screening of Antibacterial and Antifungal Activities of Six Marine Macroalgae from Coasts of Yucatán Peninsula

Abstract

Ethyl acetate partition of methanol extracts of Avrainvillea nigricans. Decaisne (Udoteaceae), Codium decorticatum. (Woodward) Howe (Codiaceae), Halymenia floresia. (Clemente) C. Agardh (Grateloupiaceae), Laurencia obtusa. (Hudson) Lamouroux (Rhodomelaceae), Sargassum filipendula. C. Agardh (Sargassaceae), and Sargassum hystrix. J. Agardh, marine macroalgae from Yucatán peninsula coasts, were screened using the well-diffusion technique against three Gram-positive bacteria, four Gram-negative bacteria, two yeasts, and two molds. The extracts inhibited the growth of Staphyloccocus aureus. at 6.25–1.56 mg/mL and Bacillus subtilis. at 6.25–0.78 mg/mL. Trichophyton mentagrophytes. growth was inhibited by extracts of Laurencia obtusa., Sargassum filipendula., and Sargassum hystrix. at 6.25–3.13 mg/mL. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were obtained by the microplate method.     

Antiplasmodial and antimicrobial activities of South African marine algal extracts

Seventy-eight crude organic fractions from nineteen species of marine algae collected from the coast of South Africa were screened for activity against a chloroquine sensitive strain of Plasmodium falciparum (D10), Staphylococcus aureus, Klebsiella pneumoniae, Mycobacterium aurum and Candida albicans. Fifteen crude fractions showed good antiplasmodical activity (IC₅₀?<10 μg/mL). The dichloromethane fraction from Sargassum heterophyllum (Turner) C. Agardh (Sargassaceae) was the most active with an IC₅₀ value of 2.8 μg/mL. Eleven extracts showed MIC values ≤?1?mg/mL against at least one of S. aureus, K. pneumoniae, M. aurum and C. albicans. The broadest spectrum of antimicrobial activity was exhibited by the aqueous-HP20 fraction of Polysiphonia incompta Harvey (Rhodomelaceae). This study shows that marine algae not only produce antimicrobial compounds but also may be a source of antimalarial lead compounds.     

Combined use of photosynthetic enzyme complexes and microalgal photosynthetic systems for rapid screening of wastewater toxicity

Because of the often episodic nature of wastewater toxicity, routine monitoring using expensive and time consuming tests can constitute an inefficient means of toxicity evaluation, particularly when negative results are generated. Cost-effective screening tests enabling the rapid detection of effluent toxicity are clearly needed, and they should be used to rapidly determine where in-depth investigations should be focused. The LuminoTox is a recently-developed screening test enabling the rapid determination of wastewater toxicity. This test is based on the inhibition of chlorophyll fluorescence emitted by photosynthetic systems. The combined use of photosynthetic enzyme complexes (PECs), isolated from higher plants, and whole photosynthetic organisms (algae) allows a wide range of toxic inhibitors to be detected within 10-15 min. The detection thresholds obtained for individual toxic chemicals indicate that algae are less sensitive to metal cations than PECs, because of the algal cell wall being ion selective. However, other toxic chemicals, such as phenolic compounds and nitrogen ammonia, acting on the last constituents of the photosynthetic enzyme complex that are degraded during the PEC extraction process, are more easily detected with algae after just 10 min of exposure. The combination of PECs and algae is not only useful for rapid toxicity screening, but yields results that are as sensitive as those of standard bioassays. Toxicity data generated with mining industry effluents demonstrate that PECs routinely prove to be as sensitive as daphnia, while algal sensitivity is comparable to that of the standard trout bioassay. An important feature of LuminoTox and algal photosynthetic system testing, however, resides in the production of their rapid and sensitive responses (10-15 min) in comparison with those of the more traditional tests (48-96 h for daphnia and trout, respectively).     

Effects of copper pre-exposure routes on the energy reserves and subsequent copper toxicity in Daphnia magna

The hypothesis was tested that copper uptake routes affect the tolerance of Daphnia magna to copper and influence the energy reserves. These were determined in D. magna juveniles that had been exposed for 4 days to water borne and/or dietary copper (algae Pseudokichneriella subcapitata loaded with copper) at nominal concentrations of 0, 10, and 100 nM. Tolerance increased with dietary copper pre-exposure reflected in 24 and 48 h LC50 values of 466 and 398 nM at 100 nM pre-exposure versus 301 and 254 nM in controls, respectively. Control animals (no copper added to their exposure medium and diet) had the lowest lipid content and consequently the lowest energy content. The current study stresses the importance of addressing dietary exposure routes in metal toxicity assessments.     

Cholinesterase inhibitory activity of two farnesylacetone derivatives from the brown alga<Emphasis Type="Italic">Sargassum sagamianum</Emphasis>

Two known farnesylacetone derivatives (1 and 2) were isolated from the Korean brown alga Sargassum sagamianum off Jeju Island, Korea. Compounds 1 and 2 were identified as (5E,10Z)-6,10,14-trimethylpentadeca-5,10-dien-2,12-dione and (5E,9E,13E)-6,10,4-trimethyl-pentadeca-5,9,13-trien-2,12-dione, respectively, by comparison with the literature data. Compounds 1 and 2 showed moderate acetylcholinesterase and butyrylcholinesterase inhibitory activities with IC50 values of 65.0 approximately 48.0 and 34.0 approximately 23.0 microM, respectively.     

鲨烯、苔条、紫菜、花菜对大鼠血清胆固醇的作用

通过喂养试验,观察了11种食物和1种食物提取物(鲨烯),对大鼠血清胆固醇浓度的作用。结果发现,鲨烯、苔条、紫菜、花菜均有降低血清T-C的作用,其中鲨烯和苔条还能促进HDL-C的增高。与对照组相比,鲨烯组大鼠血清T-C,LDL-C和VLDL-C分别下降50.5％、60.8％和53.7％,而HDL-C则增高56.5％。苔条组大鼠血清T-C,LDL-C和VLDL-C分別下降34.9％,42.7％、和31.4％,而HDL-C增高58.3％。紫菜组和花菜组大鼠血清T-C则分别下降29.4％和36.7％。     

藻类在溺死动物体内分布的示踪研究

采用核素示踪技术检测了溺死动物对~(32)P标记藻类的吸收分布情况,结果显示:溺死组内脏的~(32)P活性明显增高,组织接触法自显影可见银粒聚集;对照组内脏的~(32)P活性接近本底,自显影呈阴性反应。证明两者对藻类的吸收有显著性差异(P<0.05),认为藻类检验对鉴别溺死与抛尸入水有重要参考价值,溺死组内脏的~32P活性高低反映出藻量的多少,依次为肾>肝>脾>肌>脑,有助于准确取材提高检出率。