Toxicity microalgae

Environmental conditions are believed to be important factors for toxins production in algae. However, the results obtained until now on this topic for some toxic microalgae show a strong difference of the effect of environmental factors on the total amount of toxins produced among the different algal classes and even among different strains. 

Reduction of carbonyl groups Terpene and aromatic aldehydes (lOOppm) were reduced by microalgae. In a series of chlorinated benzaldehyde, m - or p-chlorobenzaldehyde reacted faster than the o-derivative. Due to toxicity, the substrate concentrations are difficult to increase. Asymmetric reductions of ketones by microalgae were reported. Thus, aliphatic " and aromatic " ketones were reduced. 

The occurrence of toxic compounds in plant tissues is not necessarily related to allelopathy. Allelopathy should be evidenced through experiments in which a toxic product is shown to be released from the putative aggressor, and arrives at the putative victim in functional concentrations under reasonably natural conditions (Inderjit and Callaway 2003). First of all, laboratory experiments dealing with allelopathy should demonstrate the release of a compound in the medium. Two methods to collect allelchemicals released by laboratory cultures of macrophyte or microalgae are described in Sections 5 and 6. 

III. End Point test The method for testing the toxicity of a compound (end point test) has been developed for the green microalga Pseudokirchneriella subcapitata (EPA, OECD), but can be extended to a wide range of microalgae. The method is summarized below ... 

Algae are of vital importance in the primary production of the aquatic ecosystem because they are primary producers of the food chain. Several species of green algae are used in toxicity studies of pesticides, especially herbicides such as Chlorella vulgaris, Chlorella pyrenoidosa, or the standard test microalga... 

Parent, L., Twiss, M. R. and Campbell, P. G. C. (1996). Influences of natural dissolved organic matter on the interaction of aluminum with the microalga Chlorella a test of the free-ion model of trace metal toxicity, Environ. Sci. Technol., 30, 1713-1720. 

Daranas AH, Norte M, Fernandez JJ (2001) Toxic marine microalgae. Toxicon 39 1101-1132 DeLong EE (2005) Microbial community genomics in the ocean. Nat Rev Microbiol 3 459-469 DeLong EF, Karl DM (2005) Genomic perspectives in microbial oceanography. Nature 437 336-342... 

This chapter presents a summary of the available information regarding the toxicity of surfactants in the aquatic environment and also the new data with special emphasis on the marine environment, the use of microalgae and early life-stages of fish in toxicity assays. In the last few years, one aspect related to the impact of biodegradation products of surfactants in the environment has acquired a significant relevance—the estrogenic effect—and this subject is treated in depth in Chapter 7.3 of this book. 

Phytoplankton as test organisms in toxicity bioassays with surfactants Microalgae are the basis of the aquatic trophic chain and at least 30% of the organic carbon planetary primary production is attributed to... 

Accordingly, the use of flow cytometry can improve the design of toxicity bioassays, as the detection limit of this apparatus includes cellular concentrations equal to those of microalgal populations found in natural conditions. Comparison of compositions utilised in some known toxicity tests for microalgaes are shown in Table 7.1.1. 

The use of synthetic media is preferable to natural filtered and/or sterilised media, as trace substances are expensive to remove from natural waters. In addition to this, the reproducibility of assays is improved if synthetic media are used. Different artificial seawater compositions have been used in toxicity testing. From the media investigated by our group, (see Table 7.1.2) the ASTM substitute ocean water [66] gave the best results for growing microalgae. 

Some toxicity test conditions for freshwater and marine microalgae... 

Koci, V. Lukavsky, J. Mlejnek, M. Kochankova, L. Grabic, R. Ocelka, T. 2004a, Application of a semipermeable membrane device (SPMD) for assessment of organic toxicants dangerous to the green microalga Scenedesmus subspicatus. Arch. Hydrobiol. 150 173—186. 

ASTM. Standard Guide for Conducting Static 96h Toxicity Tests with Microalgae, E1218-90 American Society for Testing and Materials Philadelphia, PA, 1990. 

The obvious and fundamental concept that results from such elucubrations, one that is now supported, documented and quantified in several experimental data sets, is that the toxic effect of a trace metal is caused by its interference with the uptake, assimilation or utilization of another, essential trace metal. Trace metals are to various degrees coordinative analogs of each other, toxicity occurs when a metal binds competitively to a ligand site involved in the transport, assimilation or utilization of an essential metal whose function it cannot emulate. (In some cases metals can replace others with reasonably good efficiency). As a result, the study of trace metal toxicity in microalgae must commence with a study of trace metal nutrition, a scientifically sound if paradoxical situation. 

Blaise, C., Ferard, J.-F. and Vasseur, P. (1998b) Microplate toxicity tests with microalgae a review, in P.G. Wells, K. Lee and C. Blaise (eds.), Microscale Testing in Aquatic Toxicolog Advances, Techniques, and Practice, CRC Press, Boca Raton, FL, pp. 269-288. 

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