Figure 3. Vin diagram indicating the numbers and overlaps for significant gene responses; all genes responding at any dose of a particular treatment were combined

ERDC TN-DOER-R4

September 2004

Figure 3.

Vin diagram indicating the numbers and overlaps for significant gene responses; all genes

responding at any dose of a particular treatment were combined

Most gene array studies have been conducted at only one dose. One exception is Bartosiewicz et

al. (2001), who conducted their exposures in mice and monitored gene expression in the livers

using a 148-gene array. The design included cadmium chloride (CdCl2) at five doses ranging

from 0.1 to 10 mg/kg, benzo-[a]-pyrene (B[a]P) at four doses ranging from 0.1 to 100 mg/kg,

and tetrachloroethylene (TCE) at three doses ranging from 10 to 1000 mg/kg. These doses cover

two to three orders of magnitude in concentrations; similarly, the current study covered two

orders of magnitude for the PAH mixture and PCB mixture, and less than two orders for TCDD.

Although many genes responded to the toxicants in the Bartosiewicz et al. study (13, 2, and 3

genes for CdCl2, B[a]P, and TCE respectively), none of them responded over the entire range

tested. The number of genes that responded over a tenfold dose range drops to 2, 2, and 0 for