Protein-sulfur dependent differences in the nerve receptors for repellent 1,4-naphthoquinones in two strains of Periplaneta americana

1. Protein-sulfur dependent differences in nerve lipoprotein receptors for repellent 1,4-naphthoquinones in two strains (i.e. LAB vs WARF) of Periplaneta americana were investigated by use of Raney nickel to specifically cleave sulfhydryls and disulfides in the in vitro proteins, and by dipping the chemoreceptors on live insect antennae into specific sulfhydryl reagents and reducing agents. 2. Raney nickel treatments demonstrated that the protein sulfurs in the two receptors which are critical to messenger 1,4-napthoquinone perception differ significantly in their accessibility or reactivity with the mild catalytic sulfur-cleaving reagent. 3. Observed differences correlated positively with other protein-sulfur dependent parameters which have been studied in these two receptors. 4. Raney nickel cleavage of sulfurs destroyed receptor electrochemical properties which are essential to the energy-transfer process in this chemoreception. 5. The various antennal dips altered the subsequent olfactory sensitivities of the two strains of live insects in manners supportive of their distinctive natures. 6. Accumulated knowledge of the receptor systems now allows predictable alterations of chemoreception sensitivity in each strain.