daf-42is an evolutionarily young gene essential for dauer development inCaenorhabditis elegans

Abstract

Under adverse environmental conditions, nematodes arrest into dauer, an alternative developmental stage for diapause. Dauer endures unfavorable environments and interacts with host animals to access favorable environments, thus playing a critical role in survival. Here, we report that inCaenorhabditis elegans,daf-42is essential for development into the dauer stage. The null mutant of daf-42 exhibited ano viable dauer phenotype in which no viable dauers were obtained in any dauer-forming conditions while there was no obvious developmental defects outside the dauer stage. A more detailed analysis revealed thatdaf-42is involved in developmental changes from the pre-dauer L2d stage to the dauer stage.daf-42encodes large, disordered proteins of various sizes that are expressed and secreted in the seam cells within a narrow time window shortly before the molt into dauer stage. Transcriptome analysis showed that the transcription of genes involved in larval physiology and dauer metabolism are highly affected by thedaf-42 mutation. Contrary to the commonsense notion that essential genes that control the life and death of an organism are thought to be conserved factors that are present across diverse species,daf-42is an evolutionarily young gene conserved only in theCaenorhabditisgenus. Our study shows that dauer formation is a vital process that is controlled not only by conserved genes but also by newly emerged genes, providing important insights into evolutionary mechanisms.