Test fish, treatment

In the area of municipal and iadustrial wastewater treatment, the principal environmental issue is the toxicity of residual flocculating agents ia the effluent. Laboratory studies have shown that cationic polymers are toxic to fish because of the iateraction of these polymers with giU. membranes. Nonionic and anionic polymers show no toxicity (82,83). Other studies have shown that ia natural systems the suspended inorganic matter and humic substances substantially reduce the toxicity of added cationic polymer, and the polymers have been used successfully ia fish hatcheries (84—86). Based on these results, the EPA has added a protocol for testing these polymers for toxicity toward fish ia the presence of humic acids (87). The addition of anionic polymers to effluent streams containing cationic polymers to reduce their toxicity has been mentioned ia the patent Hterature (83). 

Statistical Methods. Means of treatment groups for plasma retention of BSP, plasma osmolality, total plasma protein concentration and urine flow rates were compared by students t test for independent sample means (17). Plasma enzyme activity data were converted to a quantal form and analyzed by the Fischer Exact Probability Test (18). Values greater than 2 standard deviations (P < 0.05) from the control value were chosen to indicate a positive response in treated fish. 

Plasma GPT activity varied greatly in animals receiving MCB at 1 ml/kg and was significantly increased in test animals only 72 h post-treatment (Fig. 2). Conversely, plasma GPT activity was elevated (P < 0.01) in groups of fish receiving either 1.0 ml/kg or 2.0 ml/kg of CCI4 at both 24 and 48 h. 

Figure 7 shows the effect of ectopic administration of T3 to the developing zebrafish embryo. At nontoxic concentration (50 nM), only a moderate fraction (less than 5%) of the zebrafish transcriptome shows significant changes. Ossification, visual processes, and the hematopoietic system were the physiological processes most affected by the treatment, in a pattern consistent with an advancement of the development in these particular functions (Fig. 7b). Genes involved in these three processes are known targets for TDCs during metamorphosis in amphibians, teleost fishes, and lampreys [54—60], and constitute molecular counterparts of different endpoints used to test for TDC in amphibians [56, 58]. Therefore, they are excellent candidates for markers of thyroid disruptors in zebrafish at early developmental stages. Chapter 14 provides a more in-deep description of the developmental effects of thyroid disruption in zebrafish embryos.

The toxicity requirements are established per type of industry, in terms of the maximum number of times the effluents needs to be diluted to produce a no observed effect concentration (NOEC), defined as Gf for fish, Gd for daphnia, Ga for algae, and G1 for luminescent bacteria. Testing is limited to the exposure to only the appropriate Gx level, which should not produce any observed effect [the G-value corresponds with the dilution of the effluent, expressed as the lowest dilution factor (1,2,4,...) causing less than 10% mortality]. The level of maximum allowable toxicity per industrial branch is based on the level that is considered to be attainable with state-of-the-art process and/or treatment technology. Violating the toxicity requirements results in a levy, which makes state-of-the-art compliance a more economic option [12]. 

Adenovirus vectors are known to be taken into cells by endocytosis and to be released from endosomes by a well regulated process, assumed to be highly efficient [84]. It is therefore somewhat surprising that PCI is able to increase the number of adenoviral transduced cells by up to 30-fold. Nevertheless, PCI with adenoviral vectors has been tested in several different cell lines, and in all cases improved transduction has been observed [85]. The adenovirus activated by means of PCI seems to follow the same cellular pathways as for conventional adenovims infection, i.e., the fraction of transduced cells followed a linear relationship with the Coxsackie and Adenoviral Receptor (CAR) level of the cells and is integrin dependent. Furthermore, PCI increase the number of nuclearly located viral DNA molecules as measured by real-time PCR and fluorescence in situ hybridization (FISH) [86]. The results so far indicate that the main cause of the PCI effect on transduction with adenovirus is related to enhanced release of the viral particles from the endocytic vesicles into the cytosol. In accordance with what has been found for PCI of plasmids the adenovirus may be delivered after the photochemical treatment (unpublished results). However, adenovirus may be delivered up to 12 h after the photochemical treatment, which is longer than what is effective for PCI of plasmids [43, 87]. 

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