Marine Environmental Research 14 (1984) 426 428

Preliminary Studies of Growth, Reproduction and Activity of Hepatic Mixed-Function Oxidase in

Platichthys stellatus

Robert B. Spies, David W. Rice Jr & Robert R. Ireland

Environmental Sciences Division, Lawrence Livermore National Laboratory, University of California, Livermore, California 94550, USA

The cytochrome P-450-1inked, mixed-function oxidase (MFO) enzyme system is induced by exposure to aromatic hydrocarbons. Metabolically activated intermediaries of MFO-metabolized aromatic hydrocarbons bind to gamete DNA (Varanasi et al., 1982) and can cause a variety of cytotoxic effects including oocyte killing (Felton & Dobson, 1983). We examined field populations of the starry flounder Platichthys stellatus for growth and reproduction and related these measurements to MFO induction levels.

Starry flounders were collected from Monterey Bay and three sites in San Francisco Bay, California: San Pablo Bay, Richmond harbor and the Berkeley pier area. Sampling was conducted during the October 1982 through February 1983 spawning season. We examined 256 flounders for a variety of morphological measures including otolith age estimates, standard length, gonadosomatic indices and liver-to-body index. A total of 70 fish were analyzed for hepatic MFO specific activity (pmol/mg/min) by the aryl hydrocarbon hydroxylase assay. Spawning was induced in 5 fish from each sampling site in San Francisco Bay by daily injection of l mg/kg freeze-dried carp pituitary. During each of these spawnings, percent fertilization, hatching and normal larvae were measured.

Compared with Monterey Bay, San Francisco Bay flounder had enhanced oocyte development, possibly at the expense of somatic growth. Within San Francisco Bay, Berkeley fish showed a good correlation between MFO total liver activity and liver-to-body index (r =0.72).

426 Marine Environ. Res. 0141-1136/84/$03.00 © Elsevier Applied Science Publishers Ltd, England, 1984. Printed in Great Britain.

Hepatic mixed-function oxidase in starry.flounder 427

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5 10 50 100 200 MFO specific activity

Fig. 1. The MFO specific activity vs. percent fertilization for P. stellatus females collected in San Francisco Bay during December 1982 and January and February 1983,

Confidence intervals of 950% about the line are shown.

Mean hepatic M F O specific activity was significantly different between collection sites (P < 0.01). Berkeley fish had the highest mean M F O specific activity (161 _ 130, mean -t- 1 SD; n = 14) and the lowest mean percentages of fertilization success (37.2 + 32.3; n = 5). San Pablo Bay fish had the lowest mean M F O specific activity (69.5 + 86.5; n = 27) and the highest mean percentage of fertilization success (67.9 + 10.2; n = 5).

The correlation between hepatic M F O specific activity and percent fertilization, irrespective of collection site, was significant (Fig. 1). The correlation coefficient r is 0.90, and the equation for the line is y = 70.00 - 20.743 In x; P = 0-003). Percent hatching success and percent normal larvae did not correlate with M F O specific activity.

Further investigations are underway to determine the relationship between M F O activity, growth, reproduction and tissue pollutants in this species.

Work performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under Contract W- 7405-ENG-48.

428 Robert B. Spies, Dat~id W. Rice Jr, Robert R. Ireland

R E F E R E N C E S

Felton, J. S. & Dobson, R. L. (1983). The mouse oocyte toxicity assay. In: Short- term bioassays in the analysis o[ complex environmental mixtures 111 (Waters, M.D., Sandhu, S.S., Lewtas. J., Claxton, L., Chernoff, N. & Nesnow, S. (Eds)). Plenum Publishing Corporation, New York, 245 55.

Varanasi, A., Nishimoto, M., Reichert, W. L. & Stein, J. E. (1982). Metabolism and subsequent covalent binding of benzo[a]pyrene to macromolecules in gonads and liver of ripe English sole (Parophrys vetulus). Xenobiotica 12, 417-25.