Size Matters: The outer diameter of multiwalled carbon nanotubes (MWCNTs) affects gene expression in female fathead minnows (Pimephales promelas)
B.J. Carter, R.J. Griffitt, N. Brown-Peterson, H.R. Hammers, D.S. Barber
EcoArray, Inc., US
Keywords: MWCNTs, microarray, fathead minnow, gene expression
Abstract:We used oligonucleotide microarrays to examine the gene expression patterns in female fathead minnows (Pimephales promelas) exposed to two different sizes (<8 nm and 50-80 nm outer diameter) and three concentrations (0.1 mg/L, 0.3 mg/L, and 1.0 mg/L), ) of multiwalled carbon nanotubes (MWCNTs) under aerated static renewal conditions. After 48 hrs, we harvested gill, gonad and liver, and then measured gene expression using an oligonucleotide microarray. We used GeneSpring (version 9.0.3) to analyze the data, looking for differentially regulated genes (p< 0.05 and fold change >2). We observed significant differential gene expression in gill, liver and ovary tissues due to type of tissue, exposure dose, and size. After exposure to a higher dose (1.0 mg/uL) of the <8 nm MWCNTs, the number of genes differentially expressed decreased in all three tissues. All three tissues express more genes in common (by dose) after exposure to the larger size MWCNTs. The liver shows a higher percentage of genes up-regulated in response to exposure to MWCNTs regardless of size. The ovary shows more genes down-regulated after exposure to both sizes, with no differences in the expression of the gill. We conclude that size does matter in regard to MWCNTs.