Voltage-dependent sodium channels play a fundamental role in generation and propagation of action potentials in most multicellular organisms. Pyrethroid insecticides and sodium channel site 2 neurotoxins (such as batrachotoxin) presumably bind to unique sites in the membrane-embedded portion of the sodium channel. They have been very useful for studying sodium channel functions because of their very specific, well-defined effects on functional properties of the sodium channel. A class of so-called kdr or kdr-type (knockdown resistance) mutations have been identified in several insects including the German cockroach strain Ectiban-R. kdr or kdr-type insects are resistant to knockdown (rapid paralysis) and kill by pyrethroids and some of site 2 neurotoxins. Our recent restriction fragment length polymorphism analysis suggests that the kdr- type resistance is the result of a mutation(s) in the para homologous gene. The kdr-type mutation(s) in Ectiban-R most likely resides in the coding region of the para- homologous gene because the mutation(s) does not affect the sodium channel density (i.e., the regulation of the para- homologous sodium channel gene). The long-term goal of this project is to characterize the kdr-type mutation(s) that affects molecular interactions between the sodium channel and pyrethroids/site 2 neurotoxins in the German cockroach strain Ectiban-R. The specific objectives of the proposed work are: 1. Clone para-homologous sodium channel genes from Ectiban R and a genetically related pyrethroid susceptible strain (CSMA). 2. Determine and compare nucleotide sequences of the coding regions of the Ectiban-R and CSMA para-homologous genes. 3. Construct full-length cDNAs of the German cockroach para homologous gene.
