The effects of Microcystis aeruginosa cells lysate containing microcystins on physiological and molecular responses in the nematode Caenorhabditis elegans

Abstract

Microcystins (MCs) are potent toxins produced by environmental cyanobacterial blooms. The present study evaluated the effects of a Microcystis aeruginosa cyanobacterial lysate containing 0.1, 1, and 10 μg L−1 MC‐LR equivalent in the C. elegans Bristol N2 wild‐type and the effects caused by equivalent concentrations of a MC‐LR standard. The lysate was prepared from a culture of toxic strain (RST9501) originated from the Patos Lagoon Estuary (RS, Brazil). The minimal concentration necessary to cause significant effects in C. elegans under exposure to M. aeruginosa lysate or to MC‐LR standard were, respectively, 10 and 0.1 μg L−1 MC‐LR equivalent for growth and 10 and 1 μg L−1 MC‐LR equivalent for fertility. Reproduction (ie, brood size) was only affected by the exposure to 10 μg L−1 MC‐LR standard and was not affected by the lysate. The nematodes that were exposed to lysate containing 1 μg L−1 MC‐LR equivalent or MC‐LR were also analyzed for pharyngeal pumping and gene expression using RT‐qPCR. The worms’ rhythmic contractions of the pharynx were similarly affected by the lysate containing 1 μg L−1 of MC‐LR equivalent and the MC‐LR standard. The MC‐LR standard caused down‐regulation of genes related to growth (daf‐16), fertility (spe‐10), and biotransformation (gst‐2). This is the first study to evaluate the effects of a toxic cyanobacterial lysate using the C. elegans model. This study suggests the organism as a potential biotest to evaluate toxicity of natural waters containing M. aeruginosa cells and to environmental risk assessment associated to cyanobacterial bloom events.

Transgenic RFP‐RPS‐30UbL strain of the nematode Caenorhabditis elegans as a biomonitor for environmental pollutants

“…The free‐living nematode Caenorhabditis elegans , as a model organism, has been applied to environmental biomonitoring 4 . The toxicity of environmental contaminants can be evaluated by testing the worm's lethality, behavior, growth, reproduction, feeding, gene expression and so on in the biomonitoring 4–12 . Transgenic strains of C. elegans , such as hsp16::gfp and mtl‐2::gfp , have been developed and applied in environmental toxicology 2,13–15 .…”

Exposure to fluopimomide at sublethal doses causes oxidative stress in Caenorhabditis elegans regulated by insulin/insulin‐like growth factor 1‐like signaling pathway

“…Caenorhabditis elegans , as a model organism, has been used extensively in ecotoxicological research due to its short lifespan, easy cultivation, and sequenced genome 11 . In addition, C. elegans has various genes that are highly sensitive to and inducible by pollutants 12,13 . Leelaja and Rajini 14 reported that monocrotophos at sublethal doses induced significant damage to C. elegans , resulting in a decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity.…”

“…11 In addition, C. elegans has various genes that are highly sensitive to and inducible by pollutants. 12,13 Leelaja and Rajini 14 reported that monocrotophos at sublethal doses induced significant damage to C. elegans, resulting in a decrease in glutathione (GSH) content and superoxide dismutase (SOD) activity. In a previous study, exposure to glyphosate led to mitochondrial inhibition and hydrogen peroxide accumulation in the nematodes.…”