title: Effects of Cylindrospermopsis raciborskii strains (Woloszynska, 1912) Senayya & Subba Raju on the mobility of Daphnia laevis (Cladocera, Daphniidae).
abstract: Cylindrospermopsis raciborskii is a cyanobacterium distributed worldwide that is known to produce cyanotoxins. Some of the Brazilian strains can produce saxitoxins (STXs), which are classified as neurotoxins and can paralyze cladocerans .Daphnia laevis is a cladoceran with a wide distribution in the Americas and has been studied as a possible test-organism in toxicity bioassays. The present work tested the acute effect on D laevis mobility when fed a saxitoxin-producing (STX and neoSTX) C. raciborskii strain, CYRF-01, and compared the results with the effects of a non-toxic strain (NPCS-1). Neonates (6-24 hours after birth) were exposed to concentrations of C. raciborskii varying from 102 to 106 cells·mL-1 of each strain for up to three hours. The cladocerans were then transferred to a medium without toxic filaments for 24 hours. Only the organisms exposed to the STX-producing strain showed signs of the immobilization of swimming movements, confirming the effects of the toxins. There was a linear correlation between the time required to induce stopping the swimming movement, with a shorter time to needed to induce immobilization at a higher the concentration; this correlation was inverse to the time required to recover the swimming movements (longer at higher concentrations, p < 0.1). D. laevis is a tropical and subtropical species with great potential for use in toxicity tests for the detection of STXs, despite being native to and found in a great array of freshwater bodies. This is the first assay testing STX-producing and non-producing C. raciborskii strains on D. laevis, species that are both found in Brazilian ecosystems.
authors: Federal University of Itajubá ? UNIFEI, Institute of Natural Resources, Itajubá, MG, Brazil.
authors: G C
authors: GC
authors: Restani
authors: Federal University of Itajubá ? UNIFEI, Institute of Natural Resources, Itajubá, MG, Brazil.
authors: A L
authors: AL
authors: Fonseca
mesh_terms: D000818:Animals; D001681:Biological Assay; D046891:Cylindrospermopsis / Q000737:chemistry*; D003621:Daphnia / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D009068:Movement / Q000187:drug effects*; D009498:Neurotoxins / Q000302:isolation & purification / Q000633:toxicity*; D012530:Saxitoxin / Q000302:isolation & purification / Q000633:toxicity*; D013997:Time Factors; D023382:Toxicity Tests, Acute
chemical_list: D009498:Neurotoxins; D012530:Saxitoxin