Toxin accumulation and biochemical alterations in the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after exposure to microcystins

Neohelice granulata were collected during a bloom dominated by Microcystis sp. in Patos Lagoon (RS, Brazil) and then sacrificed at different times of depuration in laboratory in order to verify microcystin (MC) content and toxic effects in hepatopancreas of the estuarine crab. Biochemical measurements were: lipid peroxidation (LPO), activity of glutathione-S-transferase (GST), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). No variation of crab biochemical parameters and MC content mean value = 32 μg kg–1) was verified during the depuration period. MC content of the lyophilized bloom sample was determined by HPLC (0.129 μg mg–1). MC concentration in water at the sampling site was 1.92 μg L–1. Experimental assays were also performed via oral exposure (by gavage), in doses and time exposure varying between 0 and 55 μg kg–1 and 48 and 96 h. Analyzed variables were: GST activity (remained unaltered in all experimental conditions), LPO (augmented after 48 h in doses higher than 5.5 μg kg–1 but the opposite was observed after 96 h at the same doses) and oxygen consumption (increased in all doses and times of exposure). We conclude that (1) there is an absent or low depuration rate of MC; (2) oxidative damage should be attenuated by antioxidant defenses other than GST; (3) higher oxygen consumption should favor reactive oxygen species generation

Acúmulo de toxina e alterações bioquímicas no caranguejo estuarino Neohelice granulata (Decapoda, Bracyura) após exposição às microcistinas

Submitted by Richard Rickes ([email protected]) on 2011-10-25T12:52:27Z No. of bitstreams: 1 Toxin accumulation and biochemical alterations in the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after exposure to microcystins.pdf: 321095 bytes, checksum: f8ea972d2d6493f41b68a258882ee4a4 (MD5)Approved for entry into archive by Barbara Milbrath([email protected]) on 2011-11-04T10:43:08Z (GMT) No. of bitstreams: 1 Toxin accumulation and biochemical alterations in the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after exposure to microcystins.pdf: 321095 bytes, checksum: f8ea972d2d6493f41b68a258882ee4a4 (MD5)Made available in DSpace on 2011-11-04T10:43:08Z (GMT). No. of bitstreams: 1 Toxin accumulation and biochemical alterations in the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after exposure to microcystins.pdf: 321095 bytes, checksum: f8ea972d2d6493f41b68a258882ee4a4 (MD5) Previous issue date: 2007Neohelice granulata were collected during a bloom dominated by Microcystis sp. in Patos Lagoon (RS, Brazil) and then sacrificed at different times of depuration in laboratory in order to verify microcystin (MC) content and toxic effects in hepatopancreas of the estuarine crab. Biochemical measurements were: lipid peroxidation (LPO), activity of glutathione-S-transferase (GST), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). No variation of crab biochemical parameters and MC content mean value = 32 μg kg–1) was verified during the depuration period. MC content of the lyophilized bloom sample was determined by HPLC (0.129 μg mg–1). MC concentration in water at the sampling site was 1.92 μg L–1. Experimental assays were also performed via oral exposure (by gavage), in doses and time exposure varying between 0 and 55 μg kg–1 and 48 and 96 h. Analyzed variables were: GST activity (remained unaltered in all experimental conditions), LPO (augmented after 48 h in doses higher than 5.5 μg kg–1 but the opposite was observed after 96 h at the same doses) and oxygen consumption (increased in all doses and times of exposure). We conclude that (1) there is an absent or low depuration rate of MC; (2) oxidative damage should be attenuated by antioxidant defenses other than GST; (3) higher oxygen consumption should favor reactive oxygen species generation

Occurrence of anatoxin-a(s) during a bloom of Anabaena crassa in a water-supply reservoir in southern Brazil

Cyanobacterial blooms and the accompanying production of cyanotoxins are a serious global problem. Toxic blooms of Anabaena species are common in lagoons and reservoirs of southern Brazil. Worldwide, species of the genus Anabaena produce the majority of the known hepatotoxins (microcystins) and neurotoxins [anatoxin-a, anatoxin-a(s), and saxitoxins]. This report links a bloom of Anabaena crassa in the Faxinal Reservoir, the main water supply for the city of Caxias do Sul (400,000 inhabitants) in southern Brazil, to the occurrence of anatoxin-a(s) in the water. During the bloom period, the reservoir was strongly stratified, with higher temperatures and a deep anoxic hypolimnion. Two methods for sample concentration (direct and complete extraction) were tested, and direct extraction of samples proved to be more efficient. Water samples collected during the bloom showed 9% acetylcholinesterase inhibition at 50 mg mL−1, corresponding to 0.61μg of anatoxin-a(s) per gram of lyophilized powder. At these concentrations, symptoms of neurotoxicity and mortality were not observed in tests with Swiss albino mice. Although the concentrations of anatoxin-a(s) in the Faxinal Reservoir were low, these results are important because this is the first record of the toxin for A. crassa. Furthermore, this cyanotoxin is not yet included in Brazilian legislation for drinking-water monitoring, because of the lack of information about toxicity levels and risk calculation for oral doses. The data presented here contribute to the basis for the future inclusion of this toxin in Brazilian legislation for drinking-water quality control, and for the development of analytical methods for this toxin