Date of Award


Publication Type

Doctoral Thesis

Degree Name



Biological Sciences


Biology, General.




Aryl hydrocarbon hydroxylase (AHH) activity in two cell lines - Hepa-1c1 and H4IIE-C3 was induced to similar levels by benzo(a)-anthracence. Absolute levels varied between experiments. Relative levels, determined within experiments, were stable between experiments. Nuclear translocation of Ah receptor occurred in these lines and the noninducible HTC-SR cell line. No receptor was detectable in the noninducible Vero cell line. The Ah receptor appeared to be necessary, but not sufficient for AHH induction. Two subclones assessed for their level of inducible AHH activity, had significantly lower levels, two had approximately the same level, and three had significantly higher levels (p < 0.005) than their progenitor - Hepa-1c1. The relative level was 0.14 (+OR-) 0.09 for Hepa-1c1 subclone 1 (Hs-1), and 1.37 (+OR-) 0.48 for subclone 9 (Hs-9). These levels were stable: over 2.4 years (Hs-1), or 1 year (Hs-9); throughout the year; through routine cell storage at -80(DEGREES)C; and over approximately 190 (Hepa-1c1), 160 (Hs-1), and 150 (Hs-9) generations. The relative levels were similar when activity was induced with either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), or benzo(a)anthracene (BA). The high percentage of variant subclones and the stability of the relative levels of AHH induction of Hs-1 and Hs-9 suggests that an epigenetic mechanism contributes to control of AHH induction. No inducible activity was seen in two Vero subclones. There was no apparent correlation between relative level of induced AHH activity and: (1) quantity of total Ah receptor (cytosol plus nuclear) per mg protein; (2) receptor affinity for {('3)H} TCDD (Kd values were 7.5 nM (Hepa-1c1), 7.7 nM (Hs-1) and 7.9 nM (Hs-9; (3) subcellular distribution of {('3)H} TCDD; (4) specificity of binding and saturable nature of binding; or (5) lack of induction of receptor by BA. There was no significant difference in the quantity of nuclear receptor (per mg protein) between Hepa-1c1 and Hs-1, but significantly more nuclear receptor in Hs-9 compared to Hepa-1c1. Co-ordinate measurement of nuclear receptor and absolute induced AHH activity indicated a correlation of 0.62 between these parameters. The data suggest that the extent of the correlation between the quantity of Ah receptor translocating to the nucleus and level of induced AHH activity is mediated by other factors.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1983 .F677. Source: Dissertation Abstracts International, Volume: 44-03, Section: B, page: 0675. Thesis (Ph.D.)--University of Windsor (Canada), 1983.