Date of Award

Summer 1976

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Kneeland K. Nesius

Committee Member

Edgar F. Stillwell

Committee Member

James F. Yuan

Call Number for Print

Special Collections LD4331.B46 H458


Concentrations of cAMP increased with time in pea hypocotyls assayed at 24 hour intervals over a period of four days. The highest concentration was 20.1 pmoles/mg protein which occurred in 96 hour hypocotyl tips. Ninety-six hour root bodies (dissected region between tip and embryo) achieved a concentration of 8.6 pmoles/mg. Concentrations of cAMP in embryos remained constant around one pmole/mg for three days and values doubled on the fourth day.

Hypocotyls, after germination for 72 hours, were dissected and incubated for various lengths of time in water and 3xl0-8M IAA. Tips incubated for two hours showed a tenfold increase in cAMP over water controls. After four hours, cAMP levels in water and IAA incubated tips were comparable. Root bodies incubated in IAA showed a twofold increase in cAMP after two hours and a fourfold increase after four hours. Concentrations of cAMP in embryos remained low but increased slightly with IAA treatment.

Electron micrographs treated to localize adenyl cyclase, the enzyme responsible for cAMP production, revealed discrete membrane bound regions inside cytoplasmic vacuoles which correspond to previously localized enzymes described as acid phosphatases. It remains to be determined whether the specificity of the substrate, adenylyl imido diphosphate (AMP-PNP), used in the present study is such as to exclude all phosphatase activity other than adenyl cyclase or whether the acid phosphatase localized in earlier studies by other investigators is, in fact, an adenyl cyclase. In the differentiated cells of the root cap, adenyl cyclase was localized in discrete areas bound to the smooth endoplasmic reticulum.


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