Date of Award:

5-1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

William A. Brindley

Committee

William A. Brindley

Committee

Hugh P. Stanley

Committee

Ting H. Hsiao

Committee

Thomas M. Farley

Committee

Raymond T. Sanders

Abstract

Female American cockroaches showed definite age-dependent changes in levels of activity of the microsomal mixed function oxidase chain. Cytochrome P-450 levels, EPN-detoxication, and p-nitroanisole O-demethylation activities were very low in young adult insects but increased steadily reaching a peak at about 100 days in fat body and at about 90 days in midgut and hindgut. The activities then declined rapidly reaching levels of young insects at about 130 to 140 days of age. NADPH-NT-reductase activity was high in young insects and declined during the first few weeks of adult life. This activity too showed a peak at about 100 days.

Injections of chlorcyclizine, a known microsomal enzyme inducer, significantly increased levels of cytochrome P-450, EPN-detoxication, p-nitroanisole O-demethylation and NADPH-NT-reductase activities in young cockroaches. The inductive injections were effective, however, only before the natural activity peak was reached at 100 days. Beyond this point the injections had no inductive effect indicating that the microsomal mixed function oxidase chain in this insect is uninducible when normal enzyme levels are falling.

NADPH-NT-reductase activity in male cockroaches, while being somewhat higher than in females, showed a similar age-dependent curve with the peak occurring at about 120 days.

Age-dependent carbaryl resistance in male and female insects tended to follow levels of the mixed function oxidase activities. Fifty to sixty day old insects however, tended to be more resistant to the insecticide than microsomal enzyme levels would indicate.

RNA levels of normal female insects showed age-dependent curves similar to those of the microsomal enzyme activities being low in young adults and reaching a peak at about 100 days. Chlorcyclizine injections had little or no effect on total microsomal RNA levels. Surprisingly, actinomycin D, an RNA synthesis inhibitor, increased the inductive effect of chlorcyclizine at all ages.

Electron microscopy indicated that as enzyme levels increased the morphology of the endoplasmic reticulum changed. Tissue with low enzyme levels contained rough lamellar reticulum which became irregular or tubular in form as enzyme levels increased and finally became typical smooth reticulum in tissue with very high enzymatic activities. When enzyme levels began to fall the endoplasmic reticulum largely disappeared and concentric membrane whorls appeared in the cells. The whorls showed positive acid phosphatase activity. In older insects, which had low enzyme activities, rough lamellar endoplasmic reticulum was once again evident along with many large and very complex membrane whorls. The endoplasmic reticulum of induced tissue was characteristic of the enzyme levels attained in these insects. The ultrastructure of tissues with similar enzyme levels, whether normal or induced, tended to be very similar.

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