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Acute exposure to ustiloxin A affects growth and development of early life zebrafish, Danio rerio

Hu, Zheng, Dang, Yao, Liu, Chunsheng, Zhou, Ligang, Liu, Hao
Chemosphere 2019 v.226 pp. 851-857
Danio rerio, Ustilaginoidea virens, acute exposure, animals, dose response, food security, gene expression regulation, genes, hatching, heart rate, larvae, messenger RNA, models, mortality, plant pathogenic fungi, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction, rice, rice false smut, spikelets, toxicity, transcriptomics, ustiloxins
Ustiloxin A is a cyclopeptide mycotoxin originally isolated from rice false smut balls (FSBs) that formed in rice spikelets infected by the fungal pathogen Ustilaginoidea virens. Studies have shown that ustiloxin A was toxic to animals, but the toxicological evidence is still lacking. To reveal the negative influence of ustiloxin A on model organism, zebrafish were selected and exposed to ustiloxin A at concentrations of 0, 0.25, 2.5 or 25 μM from 2 h post-fertilization (hpf) to 144 hpf. The hatching rates of embryos in the 25 μM exposure group was 12.85% less than the control group at 96 hpf. Meanwhile, exposure to 0.25, 2.5 or 25 μM ustiloxin A resulted in a distinct dose-dependent increase in mortality rate of embryos at 96 hpf. We also found that exposed to ustiloxin A could cause some other damages on zebrafish larvae, such as growth delay and increased heart rate. In addition, the athletic behavior of zebrafish larvae exposed to ustiloxin A at 25 μM was dramatically different with that of control. Transcriptome sequencing showed that abundances of 339 transcripts (125 up-regulated and 214 down-regulated) were significantly altered in larvae exposed to 25 μM of ustiloxin A. Several of the crucial genes were validated by RT-qPCR. This is the first report on the toxicologic study of ustiloxins against model organism zebrafish. Results suggested that ustiloxins have become a potential danger for food security.