Multiple plasticity regulators reveal targets specifying an induced predatory form in nematodes. Bui, L., T. & Ragsdale, E., J. Molecular Biology and Evolution, 2019.
Multiple plasticity regulators reveal targets specifying an induced predatory form in nematodes [pdf]Paper  Multiple plasticity regulators reveal targets specifying an induced predatory form in nematodes [link]Website  abstract   bibtex   
The ability to translate a single genome into multiple phenotypes, or developmental plasticity, defines how phenotype derives from more than just genes. However, to study the evolutionary targets of plasticity and their evolutionary fates, we need to understand how genetic regulators of plasticity control downstream gene expression. Here, we have identified a transcriptional response specific to polyphenism (i.e., discrete plasticity) in the nematode Pristionchus pacificus. This species produces alternative resource-use morphs-microbivorous and predatory forms, differing in the form of their teeth, a morphological novelty-as influenced by resource availability. Transcriptional profiles common to multiple polyphenism-controlling genes in P. pacificus reveal a suite of environmentally sensitive loci, or ultimate target genes, that make up an induced developmental response. Additionally, in vitro assays show that one polyphenism regulator, the nuclear receptor (NR) NHR-40, physically binds to promoters with putative HNF4⍺ (the NR class including NHR-40) binding sites, suggesting this receptor may directly regulate genes that describe alternative morphs. Among differentially expressed genes were morph-limited genes, highlighting factors with putative "on-off" function in plasticity regulation. Further, predatory morph-biased genes included candidates-namely, all four P. pacificus homologs of Hsp70, which have HNF4⍺ motifs-whose natural variation in expression matches phenotypic differences among P. pacificus wild isolates. In summary, our study links polyphenism regulatory loci to the transcription producing alternative forms of a morphological novelty. Consequently, our findings establish a platform for determining how specific regulators of morph-biased genes may influence selection on plastic phenotypes.

Downloads: 0