Date of Award


Degree Type


University or Center

Atlanta University (AU)

Degree Name




First Advisor

Dr. Joseph B. Myers


Malic dehydrogenase (MDH) and Lactic dehydrogenase (LDH) in tissue extracts and hemolymph of the adult cockroachess Blatta arjLentalis (L), Perlplaneta americana (L) and Blaberus crannlfer (Brumelster) were identified and characterized. Identification of the above enzyme systems were carried out using polyacrylamide gel-disc electrophoresis. Charac terization consisted primarily of spectrophotometric scanning of the tissue extracts.

The tissues selected for analyses were as follows1 heart muscle, leg muscle, fat body along Kith perithoracic hemolymph.

The various tissues were placed in cold insect saline (pH 6.5) and homogenized by hand with twice their volume of Sigma alumina - 305 in a cooled mortar for 3-4 min. Crude extracts were then centrifuged at 8000 x g for 10 min8 The clear supernatants were analyzed in two ways8 (a) Separation of negatively charged protein by electrophoresis usinp polyacrylamide gels and sites of dehydrogenase activity were noted by iii immersing each gel in a specific reaction mixture, (b) Spectrophotometric determination of dehydrogenase activity was based on the rate of oxidation of NADH (decrease in optical density at 3^-0 nm) in the presence of the enzyme and the substrate.

Multiple forms of MDH were detected in leg muscle and fat body tissue extracts but only a single form was demonstrated in the hemolymph and heart muscle extracts. The speetrophotometric results demonstrated high activity of MDH in all tissues examined, LDH was absent in hemolymph, heart muscle and fat body but was present in leg muscle extracts.

It was concluded that MDH is present in cockroaches in appreci able quantities. The results also indicated that the MDH in the various tissues examined had the same characteristics but varied in concentra tion.

LDH was identified only in the leg muscle extracts of all three species of cockroaches.

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