Phenotypic plasticity is the ability of an organism to adaptively react to its environment through behavioral or developmental responses within a generation. Little is known regarding the genetic basis of how environmental cues are translated into morphological change. Genetic components must be involved for plasticity to evolve by natural selection. We have been searching for plasticity genes that contribute to the development of alternative tail phenotypes in tadpoles of the gray tree frog, Hyla versicolor. To date, we have successfully generated predator-induced deep-tailed and non-induced tadpoles, isolated nucleic acids carrying genetic information, and developed assays to characterize isolates. Messenger ribonucleic acid (mRNA), a determinant of protein synthesis, was isolated from tadpoles displaying each phenotype. Gel electrophoresis demonstrated isolation of intact RNA and mRNA, as denoted by distinctive migration patterns. Using induced tadpole mRNA as a template, we synthesized a complementary strand of deoxyribonucleic acid (cDNA). Since cDNA was resistant to treatment with Rnase, an enzyme that degrades RNA, the synthesis was deemed effective. The genetic information encoded within this cDNA corresponds to RNA messages directing protein production and hence development within the tadpole tail. Subtractive hybridization was used to distinguish mRNAs that are uniquely or preferentially expressed during induced phenotype development. A nuclease assay confirmed the single-stranded structure of subtracted cDNA product. We may now proceed to synthesize double-stranded subtracted cDNA, clone subtracted cDNAs into a plasmid vector, and sequence genes which contribute to the observed developmental shift. This work may ultimately establish whether we can think of plasticity itself as a trait under genetic control.
Jason Kuehner, ’02 Decorah, IA
Major: Biochemistry and Molecular Biology
Sponsor: Craig Tepper